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Center for Engineering Design and Entrepreneurship
Final Project Report
April 20, 2016
For
NIOSH Baghouse ENSC 39
Presented by:
_________________________ _________________________
Cameron Falkenburg Carlie Mantel
_________________________ _________________________
Ben Muyres Richard Moore
Reviewed and Accepted by:
_________________________ _________________________
Cristy McKinney Art Miller
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Contents
Part 1: Project Overview................................................................3
A: Background........................................................................................... 3
B: Deliverables .......................................................................................... 4
C: Target Design Specs.............................................................................. 5
D: Project Budget ...................................................................................... 5
Part 2: Preliminary Design .............................................................6
A: Concepts Considered ............................................................................. 6
B: Supporting Rationale ........................................................................... 16
Part 3: Prototype 1 and Testing ................................................... 19
A: Design ............................................................................................... 19
B: Chosen Pleated Filters.......................................................................... 23
C: Test Sessions ...................................................................................... 23
D: Test Results ........................................................................................ 24
Part 4: Prototype 2 and Testing .................................................... 26
A: Design ................................................................................................ 26
B: Test Sessions ...................................................................................... 29
C: Test Results ........................................................................................ 30
Part 5: Final Considerations ......................................................... 30
A: Current Conditions............................................................................... 30
B: Future Improvements.......................................................................... 30
Appendix .................................................................................. 31
A: CDC Report......................................................................................... 31
B: Schedule............................................................................................. 31
C: Prototype 1 Solidworks Drawings ......................................................... 31
D: Filter Bags .......................................................................................... 31
E: Test Plan............................................................................................. 31
F: Prototype 2 Solidworks Drawings.......................................................... 31
G: References and Research..................................................................... 31
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Part 1: Project Overview
References can be found at the end of this document in the Research Section.
A: Background
In the hydraulic fracturing industry, or “fracking” for short, workers inject a mixture of water,sand, and
other chemicals into the earth to create fissures from which to expel gas or oil. These fissures are held
open by sand particles, also known as “proppant”, so the gas or oil can be extracted1
. The fracking
process requires transporting the sand itself, which is accomplished via a variety of methods. The
pneumatic loading of the sand into transportation containers called sand movers (Fig. 1) can lead to dust
clouds of dangerous airborne particulates. These particles are small enough for workers to inhale,
potentially causing respiratory damage.
The National Institute for Occupational Safety and
Health (NIOSH),a subgroup of the Centers for
Disease Control and Prevention (CDC),is concerned
with hazardous particles in the airborne dust. When
inhaled, this dust (which includes silica and other
substances) can damage the worker’s lungs.
Eventually scar tissue builds up in the lungs,
creating breathing problems and other complications
in a condition known as Silicosis. Silicosis can result
in many harmful symptoms and develop into a fatal
illness with prolonged exposure2
. Limits for the
workers’ exposure to silica can be found in
Appendix A: CDC Report.
This harmful dust is created during the manufacturing of the proppant—the sand-like material that is
pumped into the ground during fracking—as well as the pneumatic loading of the proppant into the sand
movers3
. The dust then exits the sand movers and becomes airborne when leaving hatches on top of the
sand movers. These hatches,called thief hatches, are there to allow for airflow out of the containers
during the pneumatic loading process and also serve as man-access points for inspection of the tanks.
One method to remove the airborne dust from the air outside the sand movers is to filter the air that is
blowing through the thief hatches. A common filtration method used in the fracking industry (and many
other industries) is the baghouse filtration method. Baghouses consist of a sheltered bag made of tightly-
meshed fabric onto which dust and other airborne particles can form a thick layer, or “cake”, as air flows
through the fabric4
. When the cake builds up past a certain point (ideally before air flow is completely
Figure 1: An example of a sand mover trailer extension.
Image Credit: http://www.cambelt.com/frac-sand-storage-
trailers-4000-cu-ft.html
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restricted by the cake),the filter is cleaned by mechanical means. Common cleaning methods to remove
cake include shakers, reverse air flow, and pulse-jet air flow5
.
The goal of this project is to design, build, and test a semi-portable filtration system, such as a
miniaturized baghouse, that will fit over the hatches of the sand mover trucks currently in use in the
fracking industry. The system will be designed to filter the air effectively so that the air quality outside
the sand movers is improved, reducing the risk of workers developing Silicosis or other respiratory
illnesses. The design will also include a housing to shield the filters from inclement weather as wellas
filters that self-clean or require minimal user input to clean. Once complete, the design will require
minimal effort to install, and most importantly, reduce harmful dust exiting the sand movers to safe
levels. Our group has chosen to name this system the “Zaghouse” Microscopic Particle Filtration System
(henceforth referred to in this document as “Zaghouse” or “MPFS”).
B: Deliverables
This project will deliver:
 A full design package to NIOSH, which describes in detail, a solution to reduce the respirable
silica dust found when loading sand movers.
o This package will include a working prototype with an autonomous cleaning method.
o This prototype will be the result of a singular design created from preliminary designs
and refined through multiple iterations to the final prototype.
 A report will be included containing design details and test data as well as all applicable drawings
and 3D models.
 The final presentation of the product will be presented at the end of the Spring semester.
Partway through the project, a change was made to the deliverables in the interest of completing the
project at hand. Originally, the prototype development process and deliverables included three prototypes.
The schedule included time to test all three, and then a second stage of prototyping to combine the
successfulcomponents into a singular design; the best aspects from each concept would be combined in
order to create a single prototype. We would then build and test this prototype and refine it to create the
final prototype.
Rather than spend too much time with preliminary prototyping, however, our focus was instead
concentrated on a single design after a more rigorous brainstorming phase. Multiple different designs
were conceptualized and then combined right away without building and testing each individually. That
way, our first design would be more robust right at the start,and could be built and tested immediately at
the beginning of the second semester. These changes were approved and encouraged by our NIOSH
sponsor, and are reflected in the schedule, which can be seen in Gantt Chart form in Appendix B:
Schedule.
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C: Target Design Specs
Below are the target design specifications for the project:
Goal Measurement
Required Air Filtration Level 95% of particulate at .2 to 10 microns
Installation Requirements  1 or 2 person install
 Less than 50 lbs. per part per
person*
*No relevant NIOSH or OSHA standards
Pressure Drop During Loading 3 in. water column (inAq) max
Hatch Size
MPFS must retrofit over this size
20" x 20" Inner Diameter.
20.25" x 20.25" Outer Diameter
2.5" Lip
7.5 deg. Hatch Offset Angle
Time Between Cleaning Cycles 1 Hour Minimum
Air FlowRate 1200 cfm Max per Thief Hatch
D: Project Budget
Below is our final project budget for both Prototype 1 and Prototype 2:
Item (Prototype 1) Cost(est.)
Housing
(Krueger)
$2,534.71
(quoted)
Filters (10) $983.20 (quoted)
Hardware, etc. $320
Total: $3837.91
The current budget now includes the updated estimate for the sheet metal housing cost as manufactured
by Krueger Sheet Metal. The new estimate was more expensive than the estimate in the Project Plan due
to its change in geometry and complexity. The price of the pleated filters is quoted by filtration vendor,
Donaldson Torit. Custom pleated bags were quoted to be $98.32 each with a minimum order quantity of
10 bags. Hardware costs include the cleaning mechanism, any sealant used, all fasteners and any other
hardware required. The cleaning mechanism, which will be discussed in further detail in the following
section of this document, includes a compressor and piping for the pulse-jet system as well as a solenoid
valve. The sub-total for Prototype 1 came out to $3,767.91 which was below our approved Prototype 1
budget of $4000.00. A second prototype design was approved for manufacturing by our sponsor and was
purchased at $2,325. Including hardware costs,the grand total estimate for both prototypes is $6500.
Item (Prototype 2) Cost(est.)
Housing (Krueger) $2,325 (quoted)
Hardware costs $115 (estimated)
Subtotal (est.):
Total costestimates:
$2,440
$6,500
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Part 2: Preliminary Design
During the concept creation stage of the project, team members brainstormed concepts and narrowed
them down, consolidating the best aspects into one final design. Each member of the team produced at
least two concepts detailing the housing, bag design, and cleaning mechanism; these can be seen in the
following section. The designs were then reviewed by the team, advisor, and sponsor, and the pros and
cons of each design were discussed (weight, size, Air-to-Cloth Ratio, durability of filter style/material and
price). Then a master concept was created that integrated the most ideal components from each design.
Further research was then conducted on filtration media, including bag types, pleated bag filters vs.
standard bag filters, as well as cleaning mechanisms for each. This research and team discussion on what
would best meet the target design specifications, as well as what would be the simplest design, influenced
the decision for the chosen concept.
A: Concepts Considered
For the system design, the most critical components were the parts that house and protect the filter and a
mechanism to clean the filters during or after use. In baghouse filtration systems, there are two main bag
types, standard (or traditional) bag filters and pleated bag filters. Standard bag filters are an enclosed
tubular shape made of a filtering fabric while pleated bag filters are hollow cylinders of a similar material
arranged in pleats around the centerline. Pleated filter bags have the advantage of boasting more surface
area for similar sized filters (a quantifiable parameter called “air-to-cloth ratio” will be explained further
in the Supporting Rationale section that follows the chosen concept). Traditional bags, however are
typically less expensive because they are easier to manufacture,and since they are simply woven fabric,
can be manufactured to a larger variety of specifications including shape and length6
.
Many of the initial concepts utilized filtering bags because of their low cost and cleaning method
versatility, while avoiding pleated bag filters due to the fact that they must be cleaned via a pulse-
jet/compressed air system which can be more expensive7
. Upon further research,we ultimately decided to
use pleated -media cartridge-style filters, which can be seen in the design featured at the end of the
following section. To illustrate the reasons for the switch, the pros and cons of pleated-media cartridge-
style filters and standard bag filters are compared in a decision matrix following the initial concepts in the
Supporting Rationale section.
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Conceptsketches
Figure 2: Housing ideas and three shaker concepts.
Fig. 2 also contains three ideas for some mechanical shaker devices to clean the bags:
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1. Spring System: The first (top left in Fig. 2) design is a spring system that would hold the bag at
four points, and would then be excited by a motor or other mechanism which would shake the bag
in order to dislodge the dust cake. This design would be relatively simple and effective. It can
also be modified easily to include multiple bags if a larger air cloth ratio is needed (ie, holding
four different bags rather than the same bag at four points as shown in Fig. 3). Some drawbacks
include a relatively complex part (the spring shaker) and the relative unpredictability of the
spring-jostling system.
Figure 3: A modified version of the first shaker mechanism in Fig. 2.
2. Rotation System: The second (top right in Fig. 2) design involves a curved rod attached to the
top of the bags via rings. The rod would then be rotated along its length with a motor in order to
create oscillations in the bag (hung on the curved rod with rings) to shake off dust. Advantages
include the potential to leave the mechanism running during the loading of the sand movers to
keep the dust from accumulating. This is more to implement than shaker #1, because the motion
is controlled, predictable, and could be done with a simple motor. The problem arises in the range
of motion: the compression of the bag would be subtle rather than extreme, depending on how
exaggerated the curvature of the rod, and may not create enough motion to free the caked dust
from the bag. This design would also necessitate more height added to the housing to allow for
the curve of the rod above the bag while it rotates.
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3. Twisting System: The third (bottom right in Fig 2) design is similar to the second shaker design
with the curved rod, except the bag is rotated from an angled rod along a vertical axis rather than
a horizontal one, and would be rotated from the top of the bag rather than its side. This would
create a twisting motion; the mechanism would then spin in the reverse direction and ‘untwist’
the bag. This would be more effective than the second shaker at jostling the caked dust free,and
obtaining or manufacturing a straight rod to the necessary specifications would be easier than
with a curved rod. However, because of the twisting motion, it does not allow for the same
potential to be operating during sand mover loading.
Fig. 4 contains two additional concept designs utilizing the shaker method and are described below.
1. Multi-Bag Shaker: The concept sketch (in Fig. 4) depicts a multiple bag shaker MPFS. The dirty
air enters through the hatch at the bottom of the MPFS and is then directed through a diffuser to
lower the velocity and create a larger footprint to mount bags too. The bags are mounted at the
mounting plate and attach by hooks at the top to rods that are used in the cleaning process. The
dirty air is forced through the holes in the mounting plate and out through the bags to the clean air
outlet. The diffuser, mouting plate and sheet metal encloser all attach at one point making for
simple assembly. The rods connecting at the top of the bags attach to a electric motor shaft which
rotates back and forth quickly which shakes the dust off the inside of the bags and back into the
Sandmover. The positives of this concept include the simple assembly, multiple bag design for
better air-to-cloth ratios, relatively inexpensive shaker design and diffuser used to lower air
velocity. A down side to this conceptis that it doesn’t address how to attach the system to the
sandmover and or how to create a tight seal at the mount.
2. Layered Filter Concept: The lower concept sketch in Fig 4 describes a multiple bag design with
bags in series rather than in parallel. The dirty air enters from the hatch at the bottom of the
MPFS and is directed through multiple bags one after another before reaching the outlet. Each
bag can specifically filter different size particles to make sure that all of the particles are
removed. When a bag builds up too much dust cake,it retracts into the hopper area and shakes off
the dust into the bottom of the hopper returns the the cleaning area.
The positives of this design are that it is possible to completely remove the dust from the
sandmover and that it employs specific bags to catch all different size range of particles. The very
small air-to-cloth ratio was a huge drawback,however, because it would result in the bags
clogging up too quickly. The bags are also designed to catch up to 99% of the particles in the air
on its first pass through the bag material, which would make multiple layers redundant. There
was no need to have this many cleaning stages,and therefore this idea was ruled out.
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Figure 4: Shaker concept (top) and layered filter media concept (bottom).
Fig. 5 illustrates a concept which incorporates a pleated filter media based on investigations into the
importance of air/cloth ratio. A pleated filter media concept was developed (Fig. 5), to allow for a smaller
overall system, as pleated filters have a substantially smaller air-to-cloth ratio than traditional bag filters.
In this design, the cleaning mechanism would be an air pulse-jet system that would blow compressed air
back through the pleated bag, dislodging the dust cake from the outside of the filter. This system of
cleaning is a standard method suitable for operating while the sand blower is operating.
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Figure 5: Layered pleated material concept seen in a horizontal arrangement.
The louvers concept was an attempt to combine the cleaning mechanism and the housing. In Fig. 6 below,
the filter media can be seen attached to the housing in such a way that it would fill the entire
compartment. When airflow is introduced into the housing, the filter media expands to fill the space
therefore pressing up against mesh that surround the inside face of the housing. The mesh, in turn, makes
contact with the outside louvers. The cleaning mechanism is a mechanical cleaning process involving the
kinetic force of the louvers; when closing, they make physical contact with the mesh, which shakes the
enclosed bag to clean it. The action can be seen in Fig. 7 below. The closing action of the louvers would
also restrict airflow coming out of the housing, thus collapsing the bag.
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Figure 6: Louver concept that combines both housing and cleaning into one mechanism.
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Figure 7: Larger view of louver mechanism from Fig. 4.
The problems with this housing design are twofold. To get a reasonable air-to-cloth ratio (around 10
ft/min) means that the bag would have to be upwards of 8 feet tall and 1.5 to 2 feet in diameter, which
would be far too large to reasonably assemble or operate on the sand mover trucks. The cleaning
mechanism would also have to be very robust to clean and cut off the airflow to a bag of that size. The
cleaning process is also overly complicated and not ensured to work. The only realuse of the louvers is to
protect the bag from the outside environment, which could be built more simply as just a roof on top of
the housing.
Fig. 8 shows a bag and housing combo designed with an attempt at fixing the air-to-cloth ratio problem
experienced with bag filters. The bag is shaped with a bulbous end to increase surface area. The housing
is similar to the concept in Fig. 6, however the louvers are fixed and the housing increases in volume to
accommodate the larger bag. The design has two possible cleaning mechanisms. One method would be to
twist the bag to break up the cake that has formed on the inside of the filter. The other cleaning method
would be to shake the bag from the four loops thus dislodging the cake though mechanical means.
The cons of this design mainly come from the bag size required to provide an adequate air-to-cloth ratio
at 1200 cfm. Calculations for the size of a standard bag filter that meets a reasonable air-to-cloth ratio are
found in the Supporting Rationale section of this report.
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Figure 8: Balloon bag concept.
Fig. 9 shows two different versions of a rotating pressure differential cleaning method. A disk with a large
hole on one section of the circle would rotate underneath two (or more) bags, allowing one to fill with air
and the other to deflate, dropping the dust that had caked on the inner surface.
1. Rotating Disk, Collapsing Bag: In the first design (upper sketch in Fig. 9), the disk would rotate
quickly enough to prevent any of the bags from deflating completely (to prevent dust from
settling near the top of the bag as it collapses).
2. Rotating Disk, Partially Inflated Bag: In the second design (lower sketch in Fig. 9), each side
of the disk has a hole, with one larger to allow more air, and one smaller to allow less air but at a
higher pressure,which would leave both bags at least partially inflated at all times. The bag
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subjected to the smaller volume of air at a higher pressure would experience a pseudo-pulse-jet
effect that would keep the bag clean.
Figure 9: Two variations on a rotating pressure differential concept.
This cleaning method design involves some simple parts and easy operation, while operating
continuously during the sand loading process. Some drawbacks include the challenge of installation,
particularly sealing the air at the point where the disk is installed. It would also be tricky to make it rotate
effectively and at the desired speed. Additionally, there is no identified method of removing the dust that
falls onto the disk itself, and attaching the bags so that they do not touch each other (thus complicating the
filtration process) becomes more difficult with an increasing number of bags.
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B: Supporting Rationale
Air-to-cloth ratio is a common air filtration parameter used to estimate how fast the filters will clog due to
the dust. It is defined as the amount of air ran through the filters (in ft3
/min) divided by the total surface
area of filter material (in ft2
). This parameter essentially results in the rate that the particles hit the filters
and therefore how fast the filters clog up. The higher the air-to-cloth ratio, the faster the bags will build
up particle dust (and therefore pressure) and need to be cleaned. Fig. 11 below shows the calculation for
the ideal air-to-cloth ration of the system based on various factors. The following equation was used to
calculate these ideal air-to-cloth ratios:
V = 2.878 A B T-0.2335
L-0.06021
( 0.7471 + 0.0853 ln ( D ) )
Where:
V = Gas-to-cloth ratio (ft/min)
A = Material factor
B = Application factor
T = Temperature (°F,between 50 and 275)
L = Inlet dust loading (gr/ft3
, between 0.05 and 100)
D = Mass mean diameter of particle (µm, between 3 and 100)
Figure 10: equation for air-to-cloth calculations
The calculation shown in Fig. 10 are sourced from the same chapter in an EPA published article on sizing
of baghouses, specifically a section on how to calculate air-to-cloth ratios based on application8
. This
equation was used to calculate the needed air-to-cloth ratio for a given dust type and application as seen in
Fig. 11. This calculation was used in conjunction with other sources, both from the same article and from
other research,to calculate a design air-to-cloth ratio for a silica application.
Once the air-to-cloth ratio is calculated, the surface area required to reach that air-to-cloth ratio can be
calculated. With the total surface area,it is then possible to size either standard bag filters or pleated bag
filters. This is the process used in Fig. 11 below.
The calculations for finding the surface area of pleated filter bags were given by “Dr. Dirt”, a baghouse
specialist located in North Carolina who was consulted9
. This calculation was used to solve for pleats per
inch around the circumference,which allowed for the extrapolation of number of pleats for differing radii
of filters and can be seen half way down Fig. 11. Thus, the surface area of any size of filter was
calculable.
Bag geometry was modified to fit within the housing as well as to minimize the height of the housing.
Minimizing the size and weight of the housing to meet the ease of installation requirement was the goal.
The goal was to reduce cost in replacing the filters by utilizing as few filters as possible while maximizing
air-to-cloth ratio, thus lowering system pressure and cleaning requirements. The results can be seen in
Fig. 11:
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Figure 11: Calculations for sizing of the pleated filters.
As described above, Fig. 11 shows the calculation of the air-to-cloth ratio for sizing the filters. Once the
air-to-cloth ratio is decided upon it is possible to back out the surface area of filter media needed and by
further calculation, the pleats per inch of a pleated filter is calculated and the bags can be sized. The 9-
inch diameter by-3 ft length pleated filter bags yielded an air-to-cloth ratio of 6.95 ft/min. (as compared to
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8.33 ft/min that was calculated above for the required air-to-cloth ratio). The air-to-cloth ratio calculation
outputs a desired ratio of 7.5 ft/min that was found as a basis for silica filtering from multiple sources.
The calculations shown in Fig. 12 are sizing calculations for a standard filter baghouse as shown in the
concept from Fig. 3. A total cloth surface area was calculated using the air flow (1200 cfm) and a desired
air-to-cloth ratio (10 ft/min) for a shaker baghouse. This air-to-cloth ratio was a value pulled from the
EPA publication on baghouse sizing10
. The height required for the bags for multiple bag layouts were
calculated and required heights ranged from 4.65 to 9.3 ft. An unreasonably large amount of bag filters
were required for the short bag sizes; at the same time, limiting the number of bags involved using taller
bags in order to reach the desired air-to-cloth ratio. This tall height requirement was a main reason why
pleated filters became a more attractive option, they have greater surface area compared to total envelope.
Figure 12: Calculations for air-to-cloth ratio for different numbers/sizes of bags
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Fig. 13 below shows a design matrix that we developed in order to aid in comparing and contrasting
pleated filters versus traditional woven bags. The matrix addresses key objectives and assigns scores for
each option available, from a range of 1-5, with each option itself weighted on a 1-5 scale (with “M”
indicating a pass/fail requirement for the design). A final score for each objective was then awarded to
each bag by multiplying the objective score multiplied by the weight of that objective.
Figure 13: Design Matrix for Pleated Bag vs. Standard Bag Filters
As seen above, pleated bags scored higher than traditional bags overall on the matrix primarily because
they are more size efficient and have longer life spans. Traditional bags are easier to clean and are
relatively inexpensive; however, due to the required air-to-cloth ratio for this project, they would need to
be unreasonably large11
, which had a large negative impact on its score. This matrix was one of the
deciding factors which influenced the decision towards pleated filters and designing a pulse-jet MPFS.
Part 3: Prototype 1 and Testing
A: Design
The following design (Fig. 14-15) is a combination of the best aspects of the previous concepts,and
includes changes made after further research and investigation into baghouses and cleaning processes.
The full design can be seen in Appendix C: Prototype 1 Solidworks Files.
From the bottom up, the housing has a rubber seal on the base that presses against the thief hatch opening
of the sand mover, this prevents dust from escaping the housing. Above the hatch connection is a diffuser
to reduce the velocity of the air hitting the filters as well as to increase the housing area to install the five
filters needed to meet the necessary air to cloth ratio.
Objectives Score Score Pleated Filters Score Score Bag Fliters
Low air to cloth ratio 3 4 12
can run at higher air to
cloth ratios, more cloth
less area 2 6
Filtration at .2 microns M go both will hit this go both will hit this
Cleanability - ability to clean bag, shaker vs air jet 2 2 4
more complex cleaning
system, pulse jet 4 8
more ways than just
pulse jet, known caking
mechanism for cleaning
Acceptable Price 2 2 4 more expensive 3 6
less expensive but
requires a larger size
bag so could be
comparable
Reasonable size M go go
this is dependent on
design with air to cloth
ration of 10
Life span 3 4 12 twice the lifespan 2 6
Enviromental durabitly M go
materials able to
withstand similar
weather to bags go
Price of cleaning mechanism 2 1 2
piping, solenoid, timer,
compressor needed 3 6
Single shaking motor
and timer
Pressure durablity 3 3 9
pressure drop over time
is less than bag 2 6
pressure drop increased
due to impregnation
43 38
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The filters are pleated bag filters that attach to a mounting plate, which is welded into the housing to
reduce the need for an additional sealing surface. Five filters are equally spaced so that they receive the
same exposure to the dusty air and so that they can be cleaned without contaminating the other filters.
Five filters were chosen based on calculations of the required air-to-cloth ratio that is needed for the silica
dust application that these filters will see. Further discussion on sizing and the calculations can be found
in Supporting Rational. Air enters the filters from the sides, deposits dust on the filter media, and then
comes out the top of the filters into the roof section. Here the clean air exits the housing through a mesh
underneath the eves of the housing roof.
Inside the roof housing is the pulse-jet cleaning system. Compressed air is blown from openings in the
pipes down into the filters in pulses to remove built up dust cake on the outside of the filters. The
compressed air and the actuators for regulating the airflow come from an air compressor fitted with
solenoid valves. The compressor will be located on top of the sand mover. Further discussion can be
found below in Section C regarding jet pulse cleaning systems.
The entire housing acts as environmental protection for the filters and the cleaning mechanism, protecting
them from the elements. The roof is designed in such a way to keep water and other inclement weather
from reaching the inside of the housing and possibly effecting the filters.
Figure 14: Prototype 1 Solidworks assembly
Weather Proof Roof
Pulse-Jet Outlets
Pleated Filter
Clean Air Exit
Thief Hatch Dirty Air Inlet
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Figure 15: exploded assembly view of Prototype 1
Jet Pulse Cleaning System
Once a filtration system design was chosen, the cleaning system could be designed in more detail. Since
pleated filter bags were chosen over traditional bags, any system designed to clean the bags would have to
involve a back pulse system. This process involves expelling compressed air at high velocity from the
outside of the filters and in the reverse direction compared to how air flows while the sand movers are
operating. This process is illustrated in Fig. 16 below:
Weather Proof Roof
Pleated Filter
Mounting Plate
Pulse-Jet System
Pleated Filter
Main Filter Housing
Thief Hatch
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(a) (b) (c)
Figure 16: Illustration of the Jet Pulse cleaning process. Blue arrows denote clean air passing through the filter. Green arrows
denote back pulsed air used to clean the filters. ‘Dusty’ air refers to air contaminated with silica particles from the sand inside
the trucks.
Fig. 16a shows how air filled with dust particles from the sand moving process passes up through a filter
and out through the opening of the MPFS as cleaned air. In Fig 16b the jet pulse system delivers a pulse
of air down through the filter in the opposite direction of air during loading. This expels the dust cake
which has accumulated on the filter. In Fig. 16c a combined view of the first two images can be seen as
they take place throughout the entire MPFS. The jet pulse system is contained in the roof of the housing
above the filter openings, and remains inactive while air is being filtered and delivered outside the MPFS.
While the filters are being cleaned, the walls of the housing prevent any removed sand dust from escaping
outside the truck, and instead simply falls back into the truck where the process started.
The sand mover trucks have 12V DC outlets available for use while the sand mover is not operating. The
cleaning system was designed to take advantage of this power source. This is favorable because the
pleated filters can only be cleaned with a back pulse while the sand movers’ fans are not blowing. With
this information, a combination of an air compressor and solenoid valve would be the most effective
option for controlling the air flow into the jet pulse system. The solenoid could be electronically
programmed to turn on and off to release the compressed air automatically for a very precise and user-
friendly operation. This would be beneficial for manual tests of current and future prototypes.
A possibility of using multiple solenoid valves and multiple air pathways was considered but in the
interest of simplifying the design process,decreasing cost, and having the ability to test the first prototype
4/20/16
Page 23
as quickly as possible, a design accommodating only one solenoid valve was chosen. In place of that
single solenoid, a manual on-off lever to control the compressed air source could then be used instead for
testing purposes while solenoid valves were researched for purchase.
A preliminary mockup was designed in SolidWorks, which can be seen in Figure 17. Simplicity of design
was the priority so that we would be able to clean the filters first and foremost, and thus test the MPFS
and filters for their effectiveness. Using the models for the first prototype, dimensions of the filter housing
were recorded and a device was built out of PVC piping, adding nozzles at the end of the pipes to increase
velocity and direct the airflow.
Figure 17: Pulse Jet System Prototype 1 for five filter MPFS
B: Chosen Pleated Filters
See Appendix D: Filter Bags for product information on the chosen pleated filters.
C: Test Sessions
For a detailed test plan for both sessions see Appendix E: Test Plan.
There were two testing sessions for Prototype One. Session one was measuring concentration inside and
outside the MPFS as low level silica dust was pumped through the MPFS and filters. Three PersonalData
Recorders (PDRs) were used during testing. PDRs measured dust concentration inside the MPFS before
dust was filtered, on top of the MPFS just after passing through the filters, and one carried by a group
member walking around the testing area checking dust levels for safety purposes. PDR data was extracted
4/20/16
Page 24
using a computer software. PDR data extraction had to be done on site by a NIOSH employee due to
compatibility issues with the software and Gonzaga University computers.
Pressure drop was also measured across the housing. As dust cake built up on the filters, pressure in the
housing increased. The target pressure (indicating that the filters require cleaning) was to be measured at
around 3-4 inAq. Due to the size, number of filters and lack of testing dust, the targeted pressure needed
in order to test the cleaning mechanism was not reachable during the first session.
Weight, size and effectiveness of the roof cover was also tested in session one. The roof was placed
outside during inclement weather for severalweeks with an absorbent material underneath. Our sponsor
has been checking if any liquid has been able to penetrate through the housing roof.
In session two, the testing plan was refined so that more accurate and meaningful measurements and
measurement sequences could be taken with the PDRs. The goal in session two was to build up the
pressure on the filters so that the cleaning method could be tested. Still having not enough dust to plug all
five filters, three filters were covered,diverting that air to the remaining two filters. Because all dust was
diverted to two filters, the pressure increased to about 2 inAq, a level that allowed the cleaning method to
be tested. After all the dust was used and deposited onto the two operating filters, the air pump was shut
off. After the pressure was measured and the air pump was shut down, a short burst of air was directed
down into each of the two operating filters in order to test the air pulse-jet cleaning system.
D: Test Results
There were two testing sessions on Prototype 1. Qualitative results were the focus of the first session,
while the second session was devoted to gathering quantitative data in order to prove whether our
prototype was working or not. As stated in the test plan, our goals were to measure air filtration level,
weight, pressure drop across the filters, pulse jet cleaning process, airflow, and sealing and leakages.
The first aspect we tested was the weight of our prototype. An exact measurement of the weight was
impossible to obtain due to the lack of a scale large enough to hold the MPFS, but the weight was
estimated at over 100 lbs. The target design specification for installation, however, requires that the
MPFS be less than 50 pounds per part and can be installed by one or two people. It took three people to
lift the housing and mount it onto the test hatch. The roofing was heavier than expected as well, taking
two people to hold it while a third person attached it with the screws. Weight was one aspect of our
prototype that did not meet our desired design specifications therefore we had to address this aspect in
Prototype 2.
There was also a test for leakages and sealing problems during test day one. Large leakages were found
at the top of the housing where the bag mounting plate met the rest of the housing. These leaks were due
to the way that the MPFS was manufactured and were fixed with duct tape when found. The locations of
the leaks were noted and addressed in Prototype 2. A few small leaks were also found in the weldments,
4/20/16
Page 25
but were sealed with plumber’s putty, though since it was a problem with weld and not the actual design,
there was no easy way to fix this for Prototype 2. The last leakage area was around the base where the
MPFS attached to the testing hatch. The same plumber’s putty was applied around the base to safely seal
the entire MPFS. These leaks were caused by a weak sealbetween the MPFS and the hatch, and has been
addressed in Prototype 2.
Another aspect to test was the airflow that we were running through the system in order to verify that
testing took place in the correct conditions. Unfortunately, the testing center lacked the proper equipment
to verify this and as a result the testing setup was not completely ideal. The fan curve for the specific
model of fan used during testing could not be found, so the airflow was estimated at a little bit below the
fan max airflow of 1000 cubic feet per minute.
During the second testing session, data on the air filtration level was obtained with PDR’s,which
measured the dust concentration both inside and outside of the MPFS. Since the high concentration of
dust inside the housing could compromise the optics of the PDR’s,a single PDR was used instead, and
was flipped back and forth between measuring the inside and outside dust concentrations. Only short-term
measurements were thus made at the high concentrations, and are represented by ‘spikes’ in the data as
seen in Fig. 18b. The data consistently shows dust concentration in the MPFS as high as 400 mg/m^3,
while the concentration outside hovered around 0.1 mg/m^3. This data proves that our pleated bags were
over 99% efficient.
Figure 18: Left (a) shows inconsistent data from Session 1. Right (b) shows peaks in concentration inside versus outside of the
MPFS in taking during Session 2.
Another aspect we tested was the pressure drop across the bags themselves. As the bags get clogged up
the pressure drop across them increases. We wanted to keep our pressure drop under 3 inAq column as
our target design specification states. With the amount of dust that we had, we were unable to get the
pressure drop up to even 2 inAq column. This showed that our bags can hold a lot more dust than we
originally thought they could before they clogged up. We were able to keep a steady pressure drop of 1.4
inAq column which is well below the manufacturers’ limit of 5 inAq column and our specified limit of 3
inAq column.
4/20/16
Page 26
Finally, we analyzed our jet pulse system effectiveness. While testing our original jet pulse system we
quickly realized that there was a flaw in the design. We did not take into account that the majority of the
air would flow through the middle nozzle leaving the other four with insufficient air needed to clean the
bags. Therefore,we had to redesign our pulse jet system to a more symmetric concept to provide equal air
to all of the bags. By making our system symmetric, it assures equal airflow resistance to each of the
nozzles and therefore equal air volumes. Since our pulse jet system was ineffective, we decided to
simulate the pulse jet manually in order to see if we could clean the bags once we fixed the pulse jet
design. We measured the pressure drop across the bag before and after implementing manual air blasts.
We did this for three different nozzle sizes (1/4", 3/8", and 1/2"). We were able to drop the pressure from
our steady point of 1.4 inAq column back down to around 0.4 inAq column with all different nozzle sizes.
We used this information to redesign our Prototype 2 jet pulse.
Additionally, the weather test has shown that no inclement weather,from snow to rain to intense winds
were able infiltrate under the roof. This test shows that the design of Prototype 1 meets the environmental
test standard.
Part 4: Prototype 2 and Testing
A: Design
The modifications to Prototype 1 done in order for Prototype 2 to meet the target design specifications
that were not met by Prototype 1 as well as address issues that came up during testing. In focusing on the
portability of the MPFS, the changes made were done to reduce weight and size. To address other issues,
modifications were made on how the MPFS attached to the thief hatch. Drawings and Solidworks models
of this new design can be seen in Fig. 19 as well as Appendix F: Prototype 2 Solidworks Files.
Our design process was similar to the process used for creating Prototype 1. We knew we had to solve the
weight issue as well as the attachment mechanism, however we also made an attempt for increased
manufacturability. Each team member brought in two designs based on accomplishing the
abovementioned tasks and then the team went through a pro-con discussion in order to review each
design. The best parts of each design were integrated into a final design seen in Fig. 19 with the goal of
fully realizing the target design specifications (TDS).
The TDS requires movable sections of the MPFS weighing 50 lbs or less. Prototype 1 weighed in at an
excess of 100 lbs which was far outside of the TDS. To combat this we broke the design up into three
pieces. This three-piece design removes a number of welds as well as eliminates a leak problem area from
Prototype 1 where the filter plate attached to the housing. We separated the diffuser and the filter plate
from the main part of the housing as well as decreased the overall size of the system. The diffuser will
attach to the housing via clamps and will be sealed with a gasket while the filter plate will be bolted to the
4/20/16
Page 27
top of the housing and sealed with a gasket as well. We were able to accomplish the decrease in size due
to the pressure data taken during testing. Due to the minimal pressure drop during loading we decided that
we could remove a filter from the housing, going from five filters in Prototype 1 to four filters in
Prototype 2. This allowed us to decrease the overall footprint of the MPFS as well as decrease the cost for
the entire assembly.
Other cost cutting measures included removing the weld on the rings that attached to the filter plate in
Prototype 1, they will be held in place by the filter itself, as well as sourcing a less expensive gasket
material.
Attachment to the thief hatch was an issue in Prototype 1 due to swelling of the sheet under the stress of
the screws. Additionally, that attachment method would not have performed well in the case of a force
from the side of the housing. To improve upon this in Prototype 2, we added flanges to the diffuser with
holes drilled through them. These will contain threaded anchor magnets to firmly attach the MPFS to the
thief hatch, providing a constant downward force to maintain the seal.
4/20/16
Page 28
Figure 19: Exploded view of Prototype 2.
How the system is operated depends on the customer, however with more testing we are expecting that
instead of 8 MPFSs per sand mover, or two per tank, 4 MPFSs could be used (one per tank). This would
further lower cost. This expectation comes from designing the system with safety factors as well as for
worst case scenarios. The majority of loading that these MPFSs would see in the field are far below what
they are designed for.
Filter Mounting Plate
Main Filter Housing
Diffuser
4/20/16
Page 29
Because the number of filters decreased from five to four, our jet pulse system needed to accommodate
the change. This change was made mostly to save space, however this design allowed us to redesign the
jet pulse arrangement in a way that could split the airflow evenly and effectively.
Though conceptually it is no different from the previous design and still involves the same hardware
elements, this new pulse jet system design eliminates the main issue with the previous version, which was
uneven air distribution to the different filters. In our previous design, air travelled horizontally in three
paths across the filter openings before being directed downward into each filter. This resulted in
disproportionally more air being delivered to two of the filters (the ones closest to where the paths split).
We consulted Dr. Tailien Chen, an engineering professor at Gonzaga, on how to improve this air path so
that all filters could be cleaned equally. His advice was to deliver the flow outward from a central point
rather than have air come in through the side. That way the four filters would all have air delivered to
them simultaneously. Given this information, we decided that direct the flow downward into four paths; a
shape that was symmetrical in reference to the supply air would further ensure that air would be delivered
evenly to each nozzle. See Fig. 20 for the completed product.
B: Test Sessions
As soon as the 12V DC solenoid valve was received,the second version of the jet pulse system was built.
Once built, it was hooked up to a voltage supply and oscilloscope to verify that supplying the proper
voltage to the solenoid would result in the proper opening/closing of the valve. This test was successful.
Figure 20: Jet pulse system including 12VDC solenoid and device controller.
4/20/16
Page 30
A commercial timer was procured in order to allow testing on a timing schedule. This timer allows for
different modes of on/off activation and will be tested with the completed jet pulse system when the final
assembly is built.
Due to lead times of manufacturing for the second prototype, full testing of the jet pulse system with
compressed air and MPFS could not be completed before the submission of this report. An addendum for
this section will be submitted as soon as this testing can be completed. These tests will follow the same
parameters as the test plan used for the testing sessions for the first prototype. An additional test will
ensure the solenoid valve can operate properly with a compressed air source attached,and that the timing
control works as expected.
C: Test Results
See part B above. An addendum for this section will be submitted as soon as testing is completed.
Part 5: Final Considerations
A: Current Conditions
Because of time restraints, some conditions were assumed for the completion of this project to NIOSH
standards. An air compressor has been used during testing however, may not be readily available on work
sites. This would need to be specified for use on the work site in order to run the pulse jet system. During
testing, pulse jet firing was done on an as needed basis, depending on the level of pressure buildup across
the filters. For automated use, the timer that was sourced would be set to clean regularly. More testing is
needed to determine how long the cycles would need to be between cleanings.
B: Future Improvements
During the design and brainstorming process,some ideas were suggested that were out of the scope of our
abilities. Lacking advanced technology and time, a list of possible future improvements to the MPFS was
recorded for future prototypes and designs. A suggestion from NIOSH of a solar powered air compressor
for the cleaning system would be expensive, yet effective in not relying on the power supply of the
particular site. In the field of use,because of workers being occupied with other duties, a pressure sensor
with a kill mechanism that would shut off the main feeding fan if the pressure reached too high of a level.
This pressure sensor would be highly advantageous in preventing damage to filters and the housing and
could also be incorporated into the cleaning mechanism as well as tell when a filter needs changing.
4/20/16
Page 31
Appendix
Follows the links attached on Foliotek page. They have the same letter runners for easy access.
A: CDC Report
B: Schedule
C: Prototype 1 Solidworks Drawings
D: Filter Bags
The pleated filters used in both prototypes are sourced from Donaldson Torit. Additional resources about
filter bags in general can be found in Appendix G: References and Research.
E: Test Plan
F: Prototype 2 Solidworks Drawings
G: References and Research
The following is a list of sources and additional references used over the course of the project. References
directly cited in this document can be found in the endnotes.
GeneralReferences
"Filter Technology LTD: Dust Collector, Installation and Operating Instructions." 2016. Web.
<http://www.filtertechnologyltd.com/wp-content/uploads/2009/12/filter-technology-top-removal-pleated-
bag-installation-manual.pdf>.
"How do I calculate the optimum flow rate of compressed air for cleaning filter bags?" 2012. Web.
<http://www.mikropul.com/blog/details/optimum_flow_rate_compressed_air_for_cleaning_filter_ba
gs>.
4/20/16
Page 32
“How to Choose the Correct Baghouse Filter.” 2011. Web. <http://www.baghouse.com/2011/02/how-to-
choose-the-correct-baghouse-filter/>.
Kenchin, Oleg. "Designing a Cartridge Dust Collector for Better Filter Cleaning and Reliable
Performance.": 1. Print.
MikroPul. "Pleated Filter Cost Savings." Print.
"Pulse Jet Filter Operation and Maintenance Manual." (2009): 1. Print.
Savage, Thomas C.,Robert C. Carlozzi, and Ole Petzoldt. "Enhanced Aramid Felt Filter Bags with New
Expanded Ptfe Membrane Technology." (2000): 1. Print.
Stefan, Eric. "Dust Collection - Design and Maintenance." Web. <http://www.iaom.info/content/wp-
content/uploads/03wsc13.pdf>.
Swanson, Malcolm P. E. "Baghouse Applications." (1999): 1. Print.
<http://www.astecinc.com/images/file/literature/Astec-T-139-Baghouse-Applications-EN.pdf >.
Turner, James H.,et al. "Baghouses and Filters." Particulate Matter Controls.Research Triangle Institute,
1998. 4. Print.
Wikol, Michael, et al. "Expanded Polytetrafluoroethylene Membranes and their Applications." : 619.
Print.
Endnotes
1 What Is Fracking?: <http://www.livescience.com/34464-what-is-fracking.html>.
2 "SILICA." www.CDC.gov.Ed. NIOSH. 2016. Web. <http://www.cdc.gov/niosh/topics/silica/>.
See also: “Silicosis: Learn the Facts!”. <http://www.cdc.gov/niosh/docs/2004-108/>.
4/20/16
Page 33
3 OSHA. "Worker Exposure to Silica During Hydraulic Fracturing." www.OSHA.gov. 2016. Web.
<Worker Exposure to Silica during Hydraulic Fracturing>.
4 What is a Baghouse? <http://www.baghouse.net/Web%20Docs/Baghouse%20Definition.htm>.
See also: MikroPul video on Baghouse and Scrubber Fundamentals.
<https://www.youtube.com/watch?v=9BXEcb5RXG4>.
5 Baghouse Knowledge Base
<http://www.neundorfer.com/knowledge_base/baghouse_fabric_filters.aspx>.
See also from the same website:
Particulate Behavior and How Filters Capture Particulate:
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Operation%20Review[0].pdf>.
Filter Design:
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Design%20Review[0].pdf>.
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Design%20Variables[0].pdf>.
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Material[0].pdf>.
Operation and Maintenance:
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Maintenance%20and%20Oper
ation[0].pdf>.
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Bag%20Cleaning[0].pdf >.
Basic Uses and Cost Estimates:
<http://www.neundorfer.com/FileUploads/CMSFiles/Industrial%20Applications%20for%20Fabric%20Fi
lters[0].pdf >.
.
6 Positives and negatives of pleated bags: <http://www2.donaldson.com/torit/en-
us/technicaldocuments/pleated%20bags_a%20baghouse%20dust%20collection%20problem%20solver.pd
f>.
7 Bag cleaning basics and the mechanisms used:
<http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Bag%20Cleaning[0].pdf>
8 Calculations for Sizing a Baghouse: Contains information on particle size as well as air-to-cloth ratios
for different bag types and applications: <http://www3.epa.gov/ttncatc1/dir1/cs6ch1.pdf>
9 Dr. Dirt Consultation: <http://www.staclean.com/Terminology.htm>
10 See Endnote [8] above.
11 Merits of pleated filters over traditional bags: http://www.midwesco-tdcfilter.com/baghouse-filters/benefits-pleat-
plusr-pleated-filter-bags

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FINAL PROJECT REPORT

  • 1. Center for Engineering Design and Entrepreneurship Final Project Report April 20, 2016 For NIOSH Baghouse ENSC 39 Presented by: _________________________ _________________________ Cameron Falkenburg Carlie Mantel _________________________ _________________________ Ben Muyres Richard Moore Reviewed and Accepted by: _________________________ _________________________ Cristy McKinney Art Miller
  • 2. 4/20/16 Page 2 Contents Part 1: Project Overview................................................................3 A: Background........................................................................................... 3 B: Deliverables .......................................................................................... 4 C: Target Design Specs.............................................................................. 5 D: Project Budget ...................................................................................... 5 Part 2: Preliminary Design .............................................................6 A: Concepts Considered ............................................................................. 6 B: Supporting Rationale ........................................................................... 16 Part 3: Prototype 1 and Testing ................................................... 19 A: Design ............................................................................................... 19 B: Chosen Pleated Filters.......................................................................... 23 C: Test Sessions ...................................................................................... 23 D: Test Results ........................................................................................ 24 Part 4: Prototype 2 and Testing .................................................... 26 A: Design ................................................................................................ 26 B: Test Sessions ...................................................................................... 29 C: Test Results ........................................................................................ 30 Part 5: Final Considerations ......................................................... 30 A: Current Conditions............................................................................... 30 B: Future Improvements.......................................................................... 30 Appendix .................................................................................. 31 A: CDC Report......................................................................................... 31 B: Schedule............................................................................................. 31 C: Prototype 1 Solidworks Drawings ......................................................... 31 D: Filter Bags .......................................................................................... 31 E: Test Plan............................................................................................. 31 F: Prototype 2 Solidworks Drawings.......................................................... 31 G: References and Research..................................................................... 31
  • 3. 4/20/16 Page 3 Part 1: Project Overview References can be found at the end of this document in the Research Section. A: Background In the hydraulic fracturing industry, or “fracking” for short, workers inject a mixture of water,sand, and other chemicals into the earth to create fissures from which to expel gas or oil. These fissures are held open by sand particles, also known as “proppant”, so the gas or oil can be extracted1 . The fracking process requires transporting the sand itself, which is accomplished via a variety of methods. The pneumatic loading of the sand into transportation containers called sand movers (Fig. 1) can lead to dust clouds of dangerous airborne particulates. These particles are small enough for workers to inhale, potentially causing respiratory damage. The National Institute for Occupational Safety and Health (NIOSH),a subgroup of the Centers for Disease Control and Prevention (CDC),is concerned with hazardous particles in the airborne dust. When inhaled, this dust (which includes silica and other substances) can damage the worker’s lungs. Eventually scar tissue builds up in the lungs, creating breathing problems and other complications in a condition known as Silicosis. Silicosis can result in many harmful symptoms and develop into a fatal illness with prolonged exposure2 . Limits for the workers’ exposure to silica can be found in Appendix A: CDC Report. This harmful dust is created during the manufacturing of the proppant—the sand-like material that is pumped into the ground during fracking—as well as the pneumatic loading of the proppant into the sand movers3 . The dust then exits the sand movers and becomes airborne when leaving hatches on top of the sand movers. These hatches,called thief hatches, are there to allow for airflow out of the containers during the pneumatic loading process and also serve as man-access points for inspection of the tanks. One method to remove the airborne dust from the air outside the sand movers is to filter the air that is blowing through the thief hatches. A common filtration method used in the fracking industry (and many other industries) is the baghouse filtration method. Baghouses consist of a sheltered bag made of tightly- meshed fabric onto which dust and other airborne particles can form a thick layer, or “cake”, as air flows through the fabric4 . When the cake builds up past a certain point (ideally before air flow is completely Figure 1: An example of a sand mover trailer extension. Image Credit: http://www.cambelt.com/frac-sand-storage- trailers-4000-cu-ft.html
  • 4. 4/20/16 Page 4 restricted by the cake),the filter is cleaned by mechanical means. Common cleaning methods to remove cake include shakers, reverse air flow, and pulse-jet air flow5 . The goal of this project is to design, build, and test a semi-portable filtration system, such as a miniaturized baghouse, that will fit over the hatches of the sand mover trucks currently in use in the fracking industry. The system will be designed to filter the air effectively so that the air quality outside the sand movers is improved, reducing the risk of workers developing Silicosis or other respiratory illnesses. The design will also include a housing to shield the filters from inclement weather as wellas filters that self-clean or require minimal user input to clean. Once complete, the design will require minimal effort to install, and most importantly, reduce harmful dust exiting the sand movers to safe levels. Our group has chosen to name this system the “Zaghouse” Microscopic Particle Filtration System (henceforth referred to in this document as “Zaghouse” or “MPFS”). B: Deliverables This project will deliver:  A full design package to NIOSH, which describes in detail, a solution to reduce the respirable silica dust found when loading sand movers. o This package will include a working prototype with an autonomous cleaning method. o This prototype will be the result of a singular design created from preliminary designs and refined through multiple iterations to the final prototype.  A report will be included containing design details and test data as well as all applicable drawings and 3D models.  The final presentation of the product will be presented at the end of the Spring semester. Partway through the project, a change was made to the deliverables in the interest of completing the project at hand. Originally, the prototype development process and deliverables included three prototypes. The schedule included time to test all three, and then a second stage of prototyping to combine the successfulcomponents into a singular design; the best aspects from each concept would be combined in order to create a single prototype. We would then build and test this prototype and refine it to create the final prototype. Rather than spend too much time with preliminary prototyping, however, our focus was instead concentrated on a single design after a more rigorous brainstorming phase. Multiple different designs were conceptualized and then combined right away without building and testing each individually. That way, our first design would be more robust right at the start,and could be built and tested immediately at the beginning of the second semester. These changes were approved and encouraged by our NIOSH sponsor, and are reflected in the schedule, which can be seen in Gantt Chart form in Appendix B: Schedule.
  • 5. 4/20/16 Page 5 C: Target Design Specs Below are the target design specifications for the project: Goal Measurement Required Air Filtration Level 95% of particulate at .2 to 10 microns Installation Requirements  1 or 2 person install  Less than 50 lbs. per part per person* *No relevant NIOSH or OSHA standards Pressure Drop During Loading 3 in. water column (inAq) max Hatch Size MPFS must retrofit over this size 20" x 20" Inner Diameter. 20.25" x 20.25" Outer Diameter 2.5" Lip 7.5 deg. Hatch Offset Angle Time Between Cleaning Cycles 1 Hour Minimum Air FlowRate 1200 cfm Max per Thief Hatch D: Project Budget Below is our final project budget for both Prototype 1 and Prototype 2: Item (Prototype 1) Cost(est.) Housing (Krueger) $2,534.71 (quoted) Filters (10) $983.20 (quoted) Hardware, etc. $320 Total: $3837.91 The current budget now includes the updated estimate for the sheet metal housing cost as manufactured by Krueger Sheet Metal. The new estimate was more expensive than the estimate in the Project Plan due to its change in geometry and complexity. The price of the pleated filters is quoted by filtration vendor, Donaldson Torit. Custom pleated bags were quoted to be $98.32 each with a minimum order quantity of 10 bags. Hardware costs include the cleaning mechanism, any sealant used, all fasteners and any other hardware required. The cleaning mechanism, which will be discussed in further detail in the following section of this document, includes a compressor and piping for the pulse-jet system as well as a solenoid valve. The sub-total for Prototype 1 came out to $3,767.91 which was below our approved Prototype 1 budget of $4000.00. A second prototype design was approved for manufacturing by our sponsor and was purchased at $2,325. Including hardware costs,the grand total estimate for both prototypes is $6500. Item (Prototype 2) Cost(est.) Housing (Krueger) $2,325 (quoted) Hardware costs $115 (estimated) Subtotal (est.): Total costestimates: $2,440 $6,500
  • 6. 4/20/16 Page 6 Part 2: Preliminary Design During the concept creation stage of the project, team members brainstormed concepts and narrowed them down, consolidating the best aspects into one final design. Each member of the team produced at least two concepts detailing the housing, bag design, and cleaning mechanism; these can be seen in the following section. The designs were then reviewed by the team, advisor, and sponsor, and the pros and cons of each design were discussed (weight, size, Air-to-Cloth Ratio, durability of filter style/material and price). Then a master concept was created that integrated the most ideal components from each design. Further research was then conducted on filtration media, including bag types, pleated bag filters vs. standard bag filters, as well as cleaning mechanisms for each. This research and team discussion on what would best meet the target design specifications, as well as what would be the simplest design, influenced the decision for the chosen concept. A: Concepts Considered For the system design, the most critical components were the parts that house and protect the filter and a mechanism to clean the filters during or after use. In baghouse filtration systems, there are two main bag types, standard (or traditional) bag filters and pleated bag filters. Standard bag filters are an enclosed tubular shape made of a filtering fabric while pleated bag filters are hollow cylinders of a similar material arranged in pleats around the centerline. Pleated filter bags have the advantage of boasting more surface area for similar sized filters (a quantifiable parameter called “air-to-cloth ratio” will be explained further in the Supporting Rationale section that follows the chosen concept). Traditional bags, however are typically less expensive because they are easier to manufacture,and since they are simply woven fabric, can be manufactured to a larger variety of specifications including shape and length6 . Many of the initial concepts utilized filtering bags because of their low cost and cleaning method versatility, while avoiding pleated bag filters due to the fact that they must be cleaned via a pulse- jet/compressed air system which can be more expensive7 . Upon further research,we ultimately decided to use pleated -media cartridge-style filters, which can be seen in the design featured at the end of the following section. To illustrate the reasons for the switch, the pros and cons of pleated-media cartridge- style filters and standard bag filters are compared in a decision matrix following the initial concepts in the Supporting Rationale section.
  • 7. 4/20/16 Page 7 Conceptsketches Figure 2: Housing ideas and three shaker concepts. Fig. 2 also contains three ideas for some mechanical shaker devices to clean the bags:
  • 8. 4/20/16 Page 8 1. Spring System: The first (top left in Fig. 2) design is a spring system that would hold the bag at four points, and would then be excited by a motor or other mechanism which would shake the bag in order to dislodge the dust cake. This design would be relatively simple and effective. It can also be modified easily to include multiple bags if a larger air cloth ratio is needed (ie, holding four different bags rather than the same bag at four points as shown in Fig. 3). Some drawbacks include a relatively complex part (the spring shaker) and the relative unpredictability of the spring-jostling system. Figure 3: A modified version of the first shaker mechanism in Fig. 2. 2. Rotation System: The second (top right in Fig. 2) design involves a curved rod attached to the top of the bags via rings. The rod would then be rotated along its length with a motor in order to create oscillations in the bag (hung on the curved rod with rings) to shake off dust. Advantages include the potential to leave the mechanism running during the loading of the sand movers to keep the dust from accumulating. This is more to implement than shaker #1, because the motion is controlled, predictable, and could be done with a simple motor. The problem arises in the range of motion: the compression of the bag would be subtle rather than extreme, depending on how exaggerated the curvature of the rod, and may not create enough motion to free the caked dust from the bag. This design would also necessitate more height added to the housing to allow for the curve of the rod above the bag while it rotates.
  • 9. 4/20/16 Page 9 3. Twisting System: The third (bottom right in Fig 2) design is similar to the second shaker design with the curved rod, except the bag is rotated from an angled rod along a vertical axis rather than a horizontal one, and would be rotated from the top of the bag rather than its side. This would create a twisting motion; the mechanism would then spin in the reverse direction and ‘untwist’ the bag. This would be more effective than the second shaker at jostling the caked dust free,and obtaining or manufacturing a straight rod to the necessary specifications would be easier than with a curved rod. However, because of the twisting motion, it does not allow for the same potential to be operating during sand mover loading. Fig. 4 contains two additional concept designs utilizing the shaker method and are described below. 1. Multi-Bag Shaker: The concept sketch (in Fig. 4) depicts a multiple bag shaker MPFS. The dirty air enters through the hatch at the bottom of the MPFS and is then directed through a diffuser to lower the velocity and create a larger footprint to mount bags too. The bags are mounted at the mounting plate and attach by hooks at the top to rods that are used in the cleaning process. The dirty air is forced through the holes in the mounting plate and out through the bags to the clean air outlet. The diffuser, mouting plate and sheet metal encloser all attach at one point making for simple assembly. The rods connecting at the top of the bags attach to a electric motor shaft which rotates back and forth quickly which shakes the dust off the inside of the bags and back into the Sandmover. The positives of this concept include the simple assembly, multiple bag design for better air-to-cloth ratios, relatively inexpensive shaker design and diffuser used to lower air velocity. A down side to this conceptis that it doesn’t address how to attach the system to the sandmover and or how to create a tight seal at the mount. 2. Layered Filter Concept: The lower concept sketch in Fig 4 describes a multiple bag design with bags in series rather than in parallel. The dirty air enters from the hatch at the bottom of the MPFS and is directed through multiple bags one after another before reaching the outlet. Each bag can specifically filter different size particles to make sure that all of the particles are removed. When a bag builds up too much dust cake,it retracts into the hopper area and shakes off the dust into the bottom of the hopper returns the the cleaning area. The positives of this design are that it is possible to completely remove the dust from the sandmover and that it employs specific bags to catch all different size range of particles. The very small air-to-cloth ratio was a huge drawback,however, because it would result in the bags clogging up too quickly. The bags are also designed to catch up to 99% of the particles in the air on its first pass through the bag material, which would make multiple layers redundant. There was no need to have this many cleaning stages,and therefore this idea was ruled out.
  • 10. 4/20/16 Page 10 Figure 4: Shaker concept (top) and layered filter media concept (bottom). Fig. 5 illustrates a concept which incorporates a pleated filter media based on investigations into the importance of air/cloth ratio. A pleated filter media concept was developed (Fig. 5), to allow for a smaller overall system, as pleated filters have a substantially smaller air-to-cloth ratio than traditional bag filters. In this design, the cleaning mechanism would be an air pulse-jet system that would blow compressed air back through the pleated bag, dislodging the dust cake from the outside of the filter. This system of cleaning is a standard method suitable for operating while the sand blower is operating.
  • 11. 4/20/16 Page 11 Figure 5: Layered pleated material concept seen in a horizontal arrangement. The louvers concept was an attempt to combine the cleaning mechanism and the housing. In Fig. 6 below, the filter media can be seen attached to the housing in such a way that it would fill the entire compartment. When airflow is introduced into the housing, the filter media expands to fill the space therefore pressing up against mesh that surround the inside face of the housing. The mesh, in turn, makes contact with the outside louvers. The cleaning mechanism is a mechanical cleaning process involving the kinetic force of the louvers; when closing, they make physical contact with the mesh, which shakes the enclosed bag to clean it. The action can be seen in Fig. 7 below. The closing action of the louvers would also restrict airflow coming out of the housing, thus collapsing the bag.
  • 12. 4/20/16 Page 12 Figure 6: Louver concept that combines both housing and cleaning into one mechanism.
  • 13. 4/20/16 Page 13 Figure 7: Larger view of louver mechanism from Fig. 4. The problems with this housing design are twofold. To get a reasonable air-to-cloth ratio (around 10 ft/min) means that the bag would have to be upwards of 8 feet tall and 1.5 to 2 feet in diameter, which would be far too large to reasonably assemble or operate on the sand mover trucks. The cleaning mechanism would also have to be very robust to clean and cut off the airflow to a bag of that size. The cleaning process is also overly complicated and not ensured to work. The only realuse of the louvers is to protect the bag from the outside environment, which could be built more simply as just a roof on top of the housing. Fig. 8 shows a bag and housing combo designed with an attempt at fixing the air-to-cloth ratio problem experienced with bag filters. The bag is shaped with a bulbous end to increase surface area. The housing is similar to the concept in Fig. 6, however the louvers are fixed and the housing increases in volume to accommodate the larger bag. The design has two possible cleaning mechanisms. One method would be to twist the bag to break up the cake that has formed on the inside of the filter. The other cleaning method would be to shake the bag from the four loops thus dislodging the cake though mechanical means. The cons of this design mainly come from the bag size required to provide an adequate air-to-cloth ratio at 1200 cfm. Calculations for the size of a standard bag filter that meets a reasonable air-to-cloth ratio are found in the Supporting Rationale section of this report.
  • 14. 4/20/16 Page 14 Figure 8: Balloon bag concept. Fig. 9 shows two different versions of a rotating pressure differential cleaning method. A disk with a large hole on one section of the circle would rotate underneath two (or more) bags, allowing one to fill with air and the other to deflate, dropping the dust that had caked on the inner surface. 1. Rotating Disk, Collapsing Bag: In the first design (upper sketch in Fig. 9), the disk would rotate quickly enough to prevent any of the bags from deflating completely (to prevent dust from settling near the top of the bag as it collapses). 2. Rotating Disk, Partially Inflated Bag: In the second design (lower sketch in Fig. 9), each side of the disk has a hole, with one larger to allow more air, and one smaller to allow less air but at a higher pressure,which would leave both bags at least partially inflated at all times. The bag
  • 15. 4/20/16 Page 15 subjected to the smaller volume of air at a higher pressure would experience a pseudo-pulse-jet effect that would keep the bag clean. Figure 9: Two variations on a rotating pressure differential concept. This cleaning method design involves some simple parts and easy operation, while operating continuously during the sand loading process. Some drawbacks include the challenge of installation, particularly sealing the air at the point where the disk is installed. It would also be tricky to make it rotate effectively and at the desired speed. Additionally, there is no identified method of removing the dust that falls onto the disk itself, and attaching the bags so that they do not touch each other (thus complicating the filtration process) becomes more difficult with an increasing number of bags.
  • 16. 4/20/16 Page 16 B: Supporting Rationale Air-to-cloth ratio is a common air filtration parameter used to estimate how fast the filters will clog due to the dust. It is defined as the amount of air ran through the filters (in ft3 /min) divided by the total surface area of filter material (in ft2 ). This parameter essentially results in the rate that the particles hit the filters and therefore how fast the filters clog up. The higher the air-to-cloth ratio, the faster the bags will build up particle dust (and therefore pressure) and need to be cleaned. Fig. 11 below shows the calculation for the ideal air-to-cloth ration of the system based on various factors. The following equation was used to calculate these ideal air-to-cloth ratios: V = 2.878 A B T-0.2335 L-0.06021 ( 0.7471 + 0.0853 ln ( D ) ) Where: V = Gas-to-cloth ratio (ft/min) A = Material factor B = Application factor T = Temperature (°F,between 50 and 275) L = Inlet dust loading (gr/ft3 , between 0.05 and 100) D = Mass mean diameter of particle (µm, between 3 and 100) Figure 10: equation for air-to-cloth calculations The calculation shown in Fig. 10 are sourced from the same chapter in an EPA published article on sizing of baghouses, specifically a section on how to calculate air-to-cloth ratios based on application8 . This equation was used to calculate the needed air-to-cloth ratio for a given dust type and application as seen in Fig. 11. This calculation was used in conjunction with other sources, both from the same article and from other research,to calculate a design air-to-cloth ratio for a silica application. Once the air-to-cloth ratio is calculated, the surface area required to reach that air-to-cloth ratio can be calculated. With the total surface area,it is then possible to size either standard bag filters or pleated bag filters. This is the process used in Fig. 11 below. The calculations for finding the surface area of pleated filter bags were given by “Dr. Dirt”, a baghouse specialist located in North Carolina who was consulted9 . This calculation was used to solve for pleats per inch around the circumference,which allowed for the extrapolation of number of pleats for differing radii of filters and can be seen half way down Fig. 11. Thus, the surface area of any size of filter was calculable. Bag geometry was modified to fit within the housing as well as to minimize the height of the housing. Minimizing the size and weight of the housing to meet the ease of installation requirement was the goal. The goal was to reduce cost in replacing the filters by utilizing as few filters as possible while maximizing air-to-cloth ratio, thus lowering system pressure and cleaning requirements. The results can be seen in Fig. 11:
  • 17. 4/20/16 Page 17 Figure 11: Calculations for sizing of the pleated filters. As described above, Fig. 11 shows the calculation of the air-to-cloth ratio for sizing the filters. Once the air-to-cloth ratio is decided upon it is possible to back out the surface area of filter media needed and by further calculation, the pleats per inch of a pleated filter is calculated and the bags can be sized. The 9- inch diameter by-3 ft length pleated filter bags yielded an air-to-cloth ratio of 6.95 ft/min. (as compared to
  • 18. 4/20/16 Page 18 8.33 ft/min that was calculated above for the required air-to-cloth ratio). The air-to-cloth ratio calculation outputs a desired ratio of 7.5 ft/min that was found as a basis for silica filtering from multiple sources. The calculations shown in Fig. 12 are sizing calculations for a standard filter baghouse as shown in the concept from Fig. 3. A total cloth surface area was calculated using the air flow (1200 cfm) and a desired air-to-cloth ratio (10 ft/min) for a shaker baghouse. This air-to-cloth ratio was a value pulled from the EPA publication on baghouse sizing10 . The height required for the bags for multiple bag layouts were calculated and required heights ranged from 4.65 to 9.3 ft. An unreasonably large amount of bag filters were required for the short bag sizes; at the same time, limiting the number of bags involved using taller bags in order to reach the desired air-to-cloth ratio. This tall height requirement was a main reason why pleated filters became a more attractive option, they have greater surface area compared to total envelope. Figure 12: Calculations for air-to-cloth ratio for different numbers/sizes of bags
  • 19. 4/20/16 Page 19 Fig. 13 below shows a design matrix that we developed in order to aid in comparing and contrasting pleated filters versus traditional woven bags. The matrix addresses key objectives and assigns scores for each option available, from a range of 1-5, with each option itself weighted on a 1-5 scale (with “M” indicating a pass/fail requirement for the design). A final score for each objective was then awarded to each bag by multiplying the objective score multiplied by the weight of that objective. Figure 13: Design Matrix for Pleated Bag vs. Standard Bag Filters As seen above, pleated bags scored higher than traditional bags overall on the matrix primarily because they are more size efficient and have longer life spans. Traditional bags are easier to clean and are relatively inexpensive; however, due to the required air-to-cloth ratio for this project, they would need to be unreasonably large11 , which had a large negative impact on its score. This matrix was one of the deciding factors which influenced the decision towards pleated filters and designing a pulse-jet MPFS. Part 3: Prototype 1 and Testing A: Design The following design (Fig. 14-15) is a combination of the best aspects of the previous concepts,and includes changes made after further research and investigation into baghouses and cleaning processes. The full design can be seen in Appendix C: Prototype 1 Solidworks Files. From the bottom up, the housing has a rubber seal on the base that presses against the thief hatch opening of the sand mover, this prevents dust from escaping the housing. Above the hatch connection is a diffuser to reduce the velocity of the air hitting the filters as well as to increase the housing area to install the five filters needed to meet the necessary air to cloth ratio. Objectives Score Score Pleated Filters Score Score Bag Fliters Low air to cloth ratio 3 4 12 can run at higher air to cloth ratios, more cloth less area 2 6 Filtration at .2 microns M go both will hit this go both will hit this Cleanability - ability to clean bag, shaker vs air jet 2 2 4 more complex cleaning system, pulse jet 4 8 more ways than just pulse jet, known caking mechanism for cleaning Acceptable Price 2 2 4 more expensive 3 6 less expensive but requires a larger size bag so could be comparable Reasonable size M go go this is dependent on design with air to cloth ration of 10 Life span 3 4 12 twice the lifespan 2 6 Enviromental durabitly M go materials able to withstand similar weather to bags go Price of cleaning mechanism 2 1 2 piping, solenoid, timer, compressor needed 3 6 Single shaking motor and timer Pressure durablity 3 3 9 pressure drop over time is less than bag 2 6 pressure drop increased due to impregnation 43 38
  • 20. 4/20/16 Page 20 The filters are pleated bag filters that attach to a mounting plate, which is welded into the housing to reduce the need for an additional sealing surface. Five filters are equally spaced so that they receive the same exposure to the dusty air and so that they can be cleaned without contaminating the other filters. Five filters were chosen based on calculations of the required air-to-cloth ratio that is needed for the silica dust application that these filters will see. Further discussion on sizing and the calculations can be found in Supporting Rational. Air enters the filters from the sides, deposits dust on the filter media, and then comes out the top of the filters into the roof section. Here the clean air exits the housing through a mesh underneath the eves of the housing roof. Inside the roof housing is the pulse-jet cleaning system. Compressed air is blown from openings in the pipes down into the filters in pulses to remove built up dust cake on the outside of the filters. The compressed air and the actuators for regulating the airflow come from an air compressor fitted with solenoid valves. The compressor will be located on top of the sand mover. Further discussion can be found below in Section C regarding jet pulse cleaning systems. The entire housing acts as environmental protection for the filters and the cleaning mechanism, protecting them from the elements. The roof is designed in such a way to keep water and other inclement weather from reaching the inside of the housing and possibly effecting the filters. Figure 14: Prototype 1 Solidworks assembly Weather Proof Roof Pulse-Jet Outlets Pleated Filter Clean Air Exit Thief Hatch Dirty Air Inlet
  • 21. 4/20/16 Page 21 Figure 15: exploded assembly view of Prototype 1 Jet Pulse Cleaning System Once a filtration system design was chosen, the cleaning system could be designed in more detail. Since pleated filter bags were chosen over traditional bags, any system designed to clean the bags would have to involve a back pulse system. This process involves expelling compressed air at high velocity from the outside of the filters and in the reverse direction compared to how air flows while the sand movers are operating. This process is illustrated in Fig. 16 below: Weather Proof Roof Pleated Filter Mounting Plate Pulse-Jet System Pleated Filter Main Filter Housing Thief Hatch
  • 22. 4/20/16 Page 22 (a) (b) (c) Figure 16: Illustration of the Jet Pulse cleaning process. Blue arrows denote clean air passing through the filter. Green arrows denote back pulsed air used to clean the filters. ‘Dusty’ air refers to air contaminated with silica particles from the sand inside the trucks. Fig. 16a shows how air filled with dust particles from the sand moving process passes up through a filter and out through the opening of the MPFS as cleaned air. In Fig 16b the jet pulse system delivers a pulse of air down through the filter in the opposite direction of air during loading. This expels the dust cake which has accumulated on the filter. In Fig. 16c a combined view of the first two images can be seen as they take place throughout the entire MPFS. The jet pulse system is contained in the roof of the housing above the filter openings, and remains inactive while air is being filtered and delivered outside the MPFS. While the filters are being cleaned, the walls of the housing prevent any removed sand dust from escaping outside the truck, and instead simply falls back into the truck where the process started. The sand mover trucks have 12V DC outlets available for use while the sand mover is not operating. The cleaning system was designed to take advantage of this power source. This is favorable because the pleated filters can only be cleaned with a back pulse while the sand movers’ fans are not blowing. With this information, a combination of an air compressor and solenoid valve would be the most effective option for controlling the air flow into the jet pulse system. The solenoid could be electronically programmed to turn on and off to release the compressed air automatically for a very precise and user- friendly operation. This would be beneficial for manual tests of current and future prototypes. A possibility of using multiple solenoid valves and multiple air pathways was considered but in the interest of simplifying the design process,decreasing cost, and having the ability to test the first prototype
  • 23. 4/20/16 Page 23 as quickly as possible, a design accommodating only one solenoid valve was chosen. In place of that single solenoid, a manual on-off lever to control the compressed air source could then be used instead for testing purposes while solenoid valves were researched for purchase. A preliminary mockup was designed in SolidWorks, which can be seen in Figure 17. Simplicity of design was the priority so that we would be able to clean the filters first and foremost, and thus test the MPFS and filters for their effectiveness. Using the models for the first prototype, dimensions of the filter housing were recorded and a device was built out of PVC piping, adding nozzles at the end of the pipes to increase velocity and direct the airflow. Figure 17: Pulse Jet System Prototype 1 for five filter MPFS B: Chosen Pleated Filters See Appendix D: Filter Bags for product information on the chosen pleated filters. C: Test Sessions For a detailed test plan for both sessions see Appendix E: Test Plan. There were two testing sessions for Prototype One. Session one was measuring concentration inside and outside the MPFS as low level silica dust was pumped through the MPFS and filters. Three PersonalData Recorders (PDRs) were used during testing. PDRs measured dust concentration inside the MPFS before dust was filtered, on top of the MPFS just after passing through the filters, and one carried by a group member walking around the testing area checking dust levels for safety purposes. PDR data was extracted
  • 24. 4/20/16 Page 24 using a computer software. PDR data extraction had to be done on site by a NIOSH employee due to compatibility issues with the software and Gonzaga University computers. Pressure drop was also measured across the housing. As dust cake built up on the filters, pressure in the housing increased. The target pressure (indicating that the filters require cleaning) was to be measured at around 3-4 inAq. Due to the size, number of filters and lack of testing dust, the targeted pressure needed in order to test the cleaning mechanism was not reachable during the first session. Weight, size and effectiveness of the roof cover was also tested in session one. The roof was placed outside during inclement weather for severalweeks with an absorbent material underneath. Our sponsor has been checking if any liquid has been able to penetrate through the housing roof. In session two, the testing plan was refined so that more accurate and meaningful measurements and measurement sequences could be taken with the PDRs. The goal in session two was to build up the pressure on the filters so that the cleaning method could be tested. Still having not enough dust to plug all five filters, three filters were covered,diverting that air to the remaining two filters. Because all dust was diverted to two filters, the pressure increased to about 2 inAq, a level that allowed the cleaning method to be tested. After all the dust was used and deposited onto the two operating filters, the air pump was shut off. After the pressure was measured and the air pump was shut down, a short burst of air was directed down into each of the two operating filters in order to test the air pulse-jet cleaning system. D: Test Results There were two testing sessions on Prototype 1. Qualitative results were the focus of the first session, while the second session was devoted to gathering quantitative data in order to prove whether our prototype was working or not. As stated in the test plan, our goals were to measure air filtration level, weight, pressure drop across the filters, pulse jet cleaning process, airflow, and sealing and leakages. The first aspect we tested was the weight of our prototype. An exact measurement of the weight was impossible to obtain due to the lack of a scale large enough to hold the MPFS, but the weight was estimated at over 100 lbs. The target design specification for installation, however, requires that the MPFS be less than 50 pounds per part and can be installed by one or two people. It took three people to lift the housing and mount it onto the test hatch. The roofing was heavier than expected as well, taking two people to hold it while a third person attached it with the screws. Weight was one aspect of our prototype that did not meet our desired design specifications therefore we had to address this aspect in Prototype 2. There was also a test for leakages and sealing problems during test day one. Large leakages were found at the top of the housing where the bag mounting plate met the rest of the housing. These leaks were due to the way that the MPFS was manufactured and were fixed with duct tape when found. The locations of the leaks were noted and addressed in Prototype 2. A few small leaks were also found in the weldments,
  • 25. 4/20/16 Page 25 but were sealed with plumber’s putty, though since it was a problem with weld and not the actual design, there was no easy way to fix this for Prototype 2. The last leakage area was around the base where the MPFS attached to the testing hatch. The same plumber’s putty was applied around the base to safely seal the entire MPFS. These leaks were caused by a weak sealbetween the MPFS and the hatch, and has been addressed in Prototype 2. Another aspect to test was the airflow that we were running through the system in order to verify that testing took place in the correct conditions. Unfortunately, the testing center lacked the proper equipment to verify this and as a result the testing setup was not completely ideal. The fan curve for the specific model of fan used during testing could not be found, so the airflow was estimated at a little bit below the fan max airflow of 1000 cubic feet per minute. During the second testing session, data on the air filtration level was obtained with PDR’s,which measured the dust concentration both inside and outside of the MPFS. Since the high concentration of dust inside the housing could compromise the optics of the PDR’s,a single PDR was used instead, and was flipped back and forth between measuring the inside and outside dust concentrations. Only short-term measurements were thus made at the high concentrations, and are represented by ‘spikes’ in the data as seen in Fig. 18b. The data consistently shows dust concentration in the MPFS as high as 400 mg/m^3, while the concentration outside hovered around 0.1 mg/m^3. This data proves that our pleated bags were over 99% efficient. Figure 18: Left (a) shows inconsistent data from Session 1. Right (b) shows peaks in concentration inside versus outside of the MPFS in taking during Session 2. Another aspect we tested was the pressure drop across the bags themselves. As the bags get clogged up the pressure drop across them increases. We wanted to keep our pressure drop under 3 inAq column as our target design specification states. With the amount of dust that we had, we were unable to get the pressure drop up to even 2 inAq column. This showed that our bags can hold a lot more dust than we originally thought they could before they clogged up. We were able to keep a steady pressure drop of 1.4 inAq column which is well below the manufacturers’ limit of 5 inAq column and our specified limit of 3 inAq column.
  • 26. 4/20/16 Page 26 Finally, we analyzed our jet pulse system effectiveness. While testing our original jet pulse system we quickly realized that there was a flaw in the design. We did not take into account that the majority of the air would flow through the middle nozzle leaving the other four with insufficient air needed to clean the bags. Therefore,we had to redesign our pulse jet system to a more symmetric concept to provide equal air to all of the bags. By making our system symmetric, it assures equal airflow resistance to each of the nozzles and therefore equal air volumes. Since our pulse jet system was ineffective, we decided to simulate the pulse jet manually in order to see if we could clean the bags once we fixed the pulse jet design. We measured the pressure drop across the bag before and after implementing manual air blasts. We did this for three different nozzle sizes (1/4", 3/8", and 1/2"). We were able to drop the pressure from our steady point of 1.4 inAq column back down to around 0.4 inAq column with all different nozzle sizes. We used this information to redesign our Prototype 2 jet pulse. Additionally, the weather test has shown that no inclement weather,from snow to rain to intense winds were able infiltrate under the roof. This test shows that the design of Prototype 1 meets the environmental test standard. Part 4: Prototype 2 and Testing A: Design The modifications to Prototype 1 done in order for Prototype 2 to meet the target design specifications that were not met by Prototype 1 as well as address issues that came up during testing. In focusing on the portability of the MPFS, the changes made were done to reduce weight and size. To address other issues, modifications were made on how the MPFS attached to the thief hatch. Drawings and Solidworks models of this new design can be seen in Fig. 19 as well as Appendix F: Prototype 2 Solidworks Files. Our design process was similar to the process used for creating Prototype 1. We knew we had to solve the weight issue as well as the attachment mechanism, however we also made an attempt for increased manufacturability. Each team member brought in two designs based on accomplishing the abovementioned tasks and then the team went through a pro-con discussion in order to review each design. The best parts of each design were integrated into a final design seen in Fig. 19 with the goal of fully realizing the target design specifications (TDS). The TDS requires movable sections of the MPFS weighing 50 lbs or less. Prototype 1 weighed in at an excess of 100 lbs which was far outside of the TDS. To combat this we broke the design up into three pieces. This three-piece design removes a number of welds as well as eliminates a leak problem area from Prototype 1 where the filter plate attached to the housing. We separated the diffuser and the filter plate from the main part of the housing as well as decreased the overall size of the system. The diffuser will attach to the housing via clamps and will be sealed with a gasket while the filter plate will be bolted to the
  • 27. 4/20/16 Page 27 top of the housing and sealed with a gasket as well. We were able to accomplish the decrease in size due to the pressure data taken during testing. Due to the minimal pressure drop during loading we decided that we could remove a filter from the housing, going from five filters in Prototype 1 to four filters in Prototype 2. This allowed us to decrease the overall footprint of the MPFS as well as decrease the cost for the entire assembly. Other cost cutting measures included removing the weld on the rings that attached to the filter plate in Prototype 1, they will be held in place by the filter itself, as well as sourcing a less expensive gasket material. Attachment to the thief hatch was an issue in Prototype 1 due to swelling of the sheet under the stress of the screws. Additionally, that attachment method would not have performed well in the case of a force from the side of the housing. To improve upon this in Prototype 2, we added flanges to the diffuser with holes drilled through them. These will contain threaded anchor magnets to firmly attach the MPFS to the thief hatch, providing a constant downward force to maintain the seal.
  • 28. 4/20/16 Page 28 Figure 19: Exploded view of Prototype 2. How the system is operated depends on the customer, however with more testing we are expecting that instead of 8 MPFSs per sand mover, or two per tank, 4 MPFSs could be used (one per tank). This would further lower cost. This expectation comes from designing the system with safety factors as well as for worst case scenarios. The majority of loading that these MPFSs would see in the field are far below what they are designed for. Filter Mounting Plate Main Filter Housing Diffuser
  • 29. 4/20/16 Page 29 Because the number of filters decreased from five to four, our jet pulse system needed to accommodate the change. This change was made mostly to save space, however this design allowed us to redesign the jet pulse arrangement in a way that could split the airflow evenly and effectively. Though conceptually it is no different from the previous design and still involves the same hardware elements, this new pulse jet system design eliminates the main issue with the previous version, which was uneven air distribution to the different filters. In our previous design, air travelled horizontally in three paths across the filter openings before being directed downward into each filter. This resulted in disproportionally more air being delivered to two of the filters (the ones closest to where the paths split). We consulted Dr. Tailien Chen, an engineering professor at Gonzaga, on how to improve this air path so that all filters could be cleaned equally. His advice was to deliver the flow outward from a central point rather than have air come in through the side. That way the four filters would all have air delivered to them simultaneously. Given this information, we decided that direct the flow downward into four paths; a shape that was symmetrical in reference to the supply air would further ensure that air would be delivered evenly to each nozzle. See Fig. 20 for the completed product. B: Test Sessions As soon as the 12V DC solenoid valve was received,the second version of the jet pulse system was built. Once built, it was hooked up to a voltage supply and oscilloscope to verify that supplying the proper voltage to the solenoid would result in the proper opening/closing of the valve. This test was successful. Figure 20: Jet pulse system including 12VDC solenoid and device controller.
  • 30. 4/20/16 Page 30 A commercial timer was procured in order to allow testing on a timing schedule. This timer allows for different modes of on/off activation and will be tested with the completed jet pulse system when the final assembly is built. Due to lead times of manufacturing for the second prototype, full testing of the jet pulse system with compressed air and MPFS could not be completed before the submission of this report. An addendum for this section will be submitted as soon as this testing can be completed. These tests will follow the same parameters as the test plan used for the testing sessions for the first prototype. An additional test will ensure the solenoid valve can operate properly with a compressed air source attached,and that the timing control works as expected. C: Test Results See part B above. An addendum for this section will be submitted as soon as testing is completed. Part 5: Final Considerations A: Current Conditions Because of time restraints, some conditions were assumed for the completion of this project to NIOSH standards. An air compressor has been used during testing however, may not be readily available on work sites. This would need to be specified for use on the work site in order to run the pulse jet system. During testing, pulse jet firing was done on an as needed basis, depending on the level of pressure buildup across the filters. For automated use, the timer that was sourced would be set to clean regularly. More testing is needed to determine how long the cycles would need to be between cleanings. B: Future Improvements During the design and brainstorming process,some ideas were suggested that were out of the scope of our abilities. Lacking advanced technology and time, a list of possible future improvements to the MPFS was recorded for future prototypes and designs. A suggestion from NIOSH of a solar powered air compressor for the cleaning system would be expensive, yet effective in not relying on the power supply of the particular site. In the field of use,because of workers being occupied with other duties, a pressure sensor with a kill mechanism that would shut off the main feeding fan if the pressure reached too high of a level. This pressure sensor would be highly advantageous in preventing damage to filters and the housing and could also be incorporated into the cleaning mechanism as well as tell when a filter needs changing.
  • 31. 4/20/16 Page 31 Appendix Follows the links attached on Foliotek page. They have the same letter runners for easy access. A: CDC Report B: Schedule C: Prototype 1 Solidworks Drawings D: Filter Bags The pleated filters used in both prototypes are sourced from Donaldson Torit. Additional resources about filter bags in general can be found in Appendix G: References and Research. E: Test Plan F: Prototype 2 Solidworks Drawings G: References and Research The following is a list of sources and additional references used over the course of the project. References directly cited in this document can be found in the endnotes. GeneralReferences "Filter Technology LTD: Dust Collector, Installation and Operating Instructions." 2016. Web. <http://www.filtertechnologyltd.com/wp-content/uploads/2009/12/filter-technology-top-removal-pleated- bag-installation-manual.pdf>. "How do I calculate the optimum flow rate of compressed air for cleaning filter bags?" 2012. Web. <http://www.mikropul.com/blog/details/optimum_flow_rate_compressed_air_for_cleaning_filter_ba gs>.
  • 32. 4/20/16 Page 32 “How to Choose the Correct Baghouse Filter.” 2011. Web. <http://www.baghouse.com/2011/02/how-to- choose-the-correct-baghouse-filter/>. Kenchin, Oleg. "Designing a Cartridge Dust Collector for Better Filter Cleaning and Reliable Performance.": 1. Print. MikroPul. "Pleated Filter Cost Savings." Print. "Pulse Jet Filter Operation and Maintenance Manual." (2009): 1. Print. Savage, Thomas C.,Robert C. Carlozzi, and Ole Petzoldt. "Enhanced Aramid Felt Filter Bags with New Expanded Ptfe Membrane Technology." (2000): 1. Print. Stefan, Eric. "Dust Collection - Design and Maintenance." Web. <http://www.iaom.info/content/wp- content/uploads/03wsc13.pdf>. Swanson, Malcolm P. E. "Baghouse Applications." (1999): 1. Print. <http://www.astecinc.com/images/file/literature/Astec-T-139-Baghouse-Applications-EN.pdf >. Turner, James H.,et al. "Baghouses and Filters." Particulate Matter Controls.Research Triangle Institute, 1998. 4. Print. Wikol, Michael, et al. "Expanded Polytetrafluoroethylene Membranes and their Applications." : 619. Print. Endnotes 1 What Is Fracking?: <http://www.livescience.com/34464-what-is-fracking.html>. 2 "SILICA." www.CDC.gov.Ed. NIOSH. 2016. Web. <http://www.cdc.gov/niosh/topics/silica/>. See also: “Silicosis: Learn the Facts!”. <http://www.cdc.gov/niosh/docs/2004-108/>.
  • 33. 4/20/16 Page 33 3 OSHA. "Worker Exposure to Silica During Hydraulic Fracturing." www.OSHA.gov. 2016. Web. <Worker Exposure to Silica during Hydraulic Fracturing>. 4 What is a Baghouse? <http://www.baghouse.net/Web%20Docs/Baghouse%20Definition.htm>. See also: MikroPul video on Baghouse and Scrubber Fundamentals. <https://www.youtube.com/watch?v=9BXEcb5RXG4>. 5 Baghouse Knowledge Base <http://www.neundorfer.com/knowledge_base/baghouse_fabric_filters.aspx>. See also from the same website: Particulate Behavior and How Filters Capture Particulate: <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Operation%20Review[0].pdf>. Filter Design: <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Design%20Review[0].pdf>. <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Design%20Variables[0].pdf>. <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Material[0].pdf>. Operation and Maintenance: <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Maintenance%20and%20Oper ation[0].pdf>. <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Bag%20Cleaning[0].pdf >. Basic Uses and Cost Estimates: <http://www.neundorfer.com/FileUploads/CMSFiles/Industrial%20Applications%20for%20Fabric%20Fi lters[0].pdf >. . 6 Positives and negatives of pleated bags: <http://www2.donaldson.com/torit/en- us/technicaldocuments/pleated%20bags_a%20baghouse%20dust%20collection%20problem%20solver.pd f>. 7 Bag cleaning basics and the mechanisms used: <http://www.neundorfer.com/FileUploads/CMSFiles/Fabric%20Filter%20Bag%20Cleaning[0].pdf> 8 Calculations for Sizing a Baghouse: Contains information on particle size as well as air-to-cloth ratios for different bag types and applications: <http://www3.epa.gov/ttncatc1/dir1/cs6ch1.pdf> 9 Dr. Dirt Consultation: <http://www.staclean.com/Terminology.htm> 10 See Endnote [8] above. 11 Merits of pleated filters over traditional bags: http://www.midwesco-tdcfilter.com/baghouse-filters/benefits-pleat- plusr-pleated-filter-bags