1. Use of Gasification for drying of pulp sheets (soaking), needed to produce Makapads.
Deepak Sharma
MS Mechanical Engineering, Class of 2015
under the guidance of
Dr. Chinedum Okwudire
Fall 2014 ME 590: Final Report

2. Page 1 of 16
CONTENT
1. Introduction……………………………………………………………………………2
2. Project Description…………………………………………………………………….3-10
2.1 Social and Economic Considerations…………………………………………………...3-5
2.2 Technical Considerations………………………………………………………….5-10
2.2.1 Current state of Makapads production…………………………………………5-6
2.2.2 Gasification v/s Biomass Torrefaction…………………………………………6-8
2.2.3 Raw Material and its properties……………………………………………….. 8-10
3. Gasification Selection and Design…………………………………………………….10-14
3.1 Gasifier Selection: FEMA v/s Imbert Design…………………………………………..10-11
3.2 Design of Imbert Gasifier………………………………………………………………11-14
4. Future Work…………………………………………………………………………...14
5. Conclusion………………………………………………………………………….....14-15
6. References……………………………………………………………………………..15-16
7. Appendix………………………………………………………………………………16

3. Page 2 of 16
1. Introduction
UNICEF estimates that in Africa 1 in every 10 girls do not attend school during menstruation, severely
affecting their education and causing some of them to drop out of school [1]. In India, only 12% of its 355
million menstruating women use sanitary pads [2]. Serious health and environmental concerns arise when
alternative methods (e.g., rags, dried leaves and old newspapers) are used to deal with menstruation.
This project is focused on designing low-cost and energy-efficient machines to be used for scaling up the
production of low-cost and biodegradable sanitary pads known as Makapads. The Makapad was developed
by Prof. Moses Musaazi at Makerere University, Uganda, out of the need to provide pads for girls who
would frequently miss school during their menstruation periods due to their inability to afford off-the-shelf
pads. Makapads are currently manufactured using locally sourced raw materials (i.e., papyrus and recycled
paper) which are processed using simple machines made in Uganda. The machines are either manually
driven or are solar powered, making them environment-friendly and usable in rural settings. Moreover, the
simplicity of the manufacturing process and machines makes it possible for workers (who are typically
housewives) to work from home so that they can generate livelihoods without disrupting their family
routines. Technology for Tomorrow (T4T) Ltd, the outfit that manufactures Makapads, currently produces
7.5 million Makapads per year and directly employs 240 people. Its goal is to scale up the annual production
capacity by 300% and enhance the quality of its product to meet growing market needs. The challenge for
me is to help T4T to make machines that help boost its productivity and lower the costs of Makapads, while
cultivating the social and environmental impacts it has already achieved.
The project focuses on using gasification to harness heat content of outer layer of Papyrus as a biomass input
to gasifier. Imbert (Downdraft) gasifier is the most optimal type of gasifier which could be used to produce
clean producer gas; which could further be harnessed to produce heat or electricity.

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2. Project Description
The project development started with understanding the market, where the technology will eventually be
implemented. To understand this, the focus has to be concentrated on the Base of the Pyramid (BOP). To do
so, I read the book “Next General Business Strategies for the Base of the Pyramid” by Prof. Ted London and
Stuart L. Hart [3]. This book comments on the critical measures an organization should take to fit in the
peculiar BOP markets while taking the social and economics of the market into consideration. Apart from
this, the selection and use of technology to harness energy from the surroundings is also important for the
sustainability of the whole Makapads production process. The following section discusses all these
components in detail.
2.1. Social and Economic considerations:
Working with the Base of the Pyramid (BOP) is quite different from working for the Top of the Pyramid
(TOP) consumers. The sole difference which many people fail to recognize is that while dealing with BOP,
one needs to create market as there’s no existing market tailored for one’s specific product. Market creation
is possible only if the leadership team gives up their assumptions and inherited biases before starting with the
design, pilot and scale of the project. This could be done by being patient, staying longer and coming back
for feedback! Apart from working in a closely knitted and designated team, the team should look outside for
further collaborations. These collaborations provided a co-mingled competitive advantage which adds value
to the business model. For e.g. Shakti, an initiative by Unilever to distribute its retail goods focused on
collaborating with women in rural holdings to make them entrepreneurs so that they can set up their own shops
and support their family. This initiative grew wide due to this collaboration which gave Unilever a competitive
advantage over other FMCG brands and initiatives. Unilever also collaborated with self-help groups (SHGs)
and 350 non-profit organizations (incl. CARE). The unique proposition of these collaborations is that they
aren’t based on any business contract but on mutual interest and advantage. CARE and Unilever stayed
together just because both of them found value in each other’s work and business model. This was about
growing wide and strengthening the market cap. Manufacturers of Makapads is targeting the BOP market with
an existing category of product. To be the part of the BOP, they constantly need to involve and empower
women labours such that they’re able to manage both work and household chores.
Implementing a new model is almost similar to starting fresh with the market, except for the fact that initial
understanding from past experiences help in making a firm start (not quick start). This requires growing deep
into the market, i.e. socially embedding oneself into the consumer group (here the dwellers of BOP). To grow
deep, one needs to do the following two things:
a.) Get market specific information;
b.) Interpret the information.
People who work for the benefit of BOP can range from “philanthrocapitalists” (e.g. Gates Foundation,
google.org); “patient capitalists” (private capital structures aiming to receive social return; e.g. E+co, Root
Capital, academic institutions, etc.) and “social entrepreneurs”. Patient capitalists and social entrepreneurs can
come together to provide the unmet needs to the society. Entrepreneurs come up with ideas to implement and
patient capitalists further help in organizational capability management and provide capital to scale. This
model is analogous to the current “entrepreneur” and “startup incubator/accelerator” model. This partnership
of a social entrepreneur and capitalists can thrive only if the “capitalist” view is kept aside during the process.
A greater tolerance for risk, patience over the time span and willingness to forego financial gains over social
impact are the key requirements for a successful partnership. Further, to succeed in the BOP market, these
groups need to focus on some or all of the following key areas:
 Cost addition without value degradation: As done by Aravind Eye Hospital, Madurai, India- for a
cataract surgery that the hospital charges at $50-$75 in comparison to $2500-$3000 in developed countries-
by inventing workflow innovations (one being employment of low cost orderlies and junior nurses);
 Developing BOP-Centric Management System: When a BOP business thrives and expands into multiple
offices and locations; keeping the heart of the operations at the site of work is a big challenge which if
fulfilled, pays well;

5. Page 4 of 16
 Implementing human centric design thinking: Value, affordability and effective logistics is at the core
of human centred design for the BOP market. Apart from the consumer’s need, their usage pattern is equally
important while designing product/ services;
 Developing trust with the BOP: The most crucial pillar for any successful BOP market implementation.
Developing a close knit family atmosphere where mutual understanding for needs and necessities is what
differentiates a successful and failed business.
While focusing on the aforementioned areas, the companies targeting the BOP market make a severe mistake
of ignoring the environment. Flourishing collaboration and innovation brings in some problems with it. Here,
the problem is ramping of sales and profit by using unsustainable means to sell products/ services. Hence, to
keep the BOP market on track, a green leap is required. New technologies like renewable energy,
bio-materials, wireless IT, nanotechnology and many more can address the unsustainable challenge. But, the
biggest challenge along with the environmental challenge is the displacement of existing technology. Green
technology is disruptive in nature and this acts like a big barrier while the technology is introduced to people,
who already are accustomed to previous unsustainable technology. This problem is dealt by devising a
strategic mechanism called Entrepreneurial Judo. As per this strategy, instead of focusing on the TOP while
applying green technology, one should bring their focus on the underserved BOP. This approach will result in
sustainable usage and reserve of natural resources; which in turn will generate profit for the BOP dwellers.
Providing sustainable products will help the BOP to thrive and move from bottom to top; into the TOP range.
After reaching the TOP, this section of society will lack the inertia in getting accustomed to green technology
and therefore, will close the loop for the green leap. But as mentioned before, for any business for BOP to
thrive, patience, staying longer and coming back are at the core.
But, given that one masters all the aforementioned techniques, is the product going to be successful in the
BOP? Mostly, no. It is so because by now, we haven’t constituted a major learning in our approach to solve a
problem at BOP. Considering the example of Procter and Gamble. P&G, started working on water purification
process for the BOP market and came up with sachets which could each clean 10 litres of water for a cost of
$0.10. The product was an outcome of an extensive research and anthropological finding done by researchers
who found that the product should have the following features:
a.) should show visible signs of clean water after usage;
b.) should be affordable;
c.) should be a at home convenience product.
This product covered all the above three features but still had a retention rate of 5%. Why so low? This has to
do with something more than product. This is the point where the concept of “market entry” and “market
creation” comes into being. Rural dwellers who were sold the water purification sachets had two issues to deal
with, when seen from their viewpoint:
a.) Why am I paying for this sachet and what value?
b.) Why should I incorporate this new product and its usage in my well-structured life and monthly/ daily
budget?
The $0.10 ‘sachet’ to BOP is just like $5000 “Segway” to Americans. You don’t know what you have to
pay and why you need it? This is rightly mentioned by Malcolm Gladwell in “The Tipping Point”,
“Prediction, in the field where prediction is not possible, is no more than a prejudice.” This is the major
issue which comes up when a product which needs to create new market; enters as a product of existing
market. Therefore, to reach of the BOP with such products which are new to their life, a “market creation”
strategy is required. This strategy not just brings in the product, but knits the product well into the fabric of
the lives of people who are new to it and therefore, provides a basis for people to incorporate the product as a
constituent of their life. This was done by Z-Boys who started using skateboards in empty swimming pools in
drought days in LA. This gave people a sense of making use of things they already possess (here, swimming
pool). This value creation triggered the interest in skateboards and adventure involved in its usage and
eventually, gave rise to the half pipe skate parks we see at numerous sites. Therefore, moving ahead from this
example and that of P&G’s, we can say that the process of market creation requires two major steps:
 Framing the value proposition;
 Defining the strategic innovation process.

6. Page 5 of 16
Framing is a major part of creating a new market. So as to show value in the product, open ended value
proposition has been found to be an effective tool. Cross-linking the different chores and components of
people’s life with a single product adds a value to that product. For e.g. Solae industry, India wanted to sell
soybean products to the low-end customers. To do so, they went on producing the 50% cheaper version of the
market product and created food court events that symbolized family, fun, health and food. Therefore, just
one product provided enough compulsion to inherit it in one’s life.
Strategizing the market creation process involves the following three steps:
 Seeding: This is the same strategy applied by Z-Boys and is the sense making process for the product. If
the product can create a wave of emotional commitment with least amount of chaos on one’s normal
routine, then the product makes some sense in one’s life fabric.
 Base building: This is the process of consolidating on seeding the idea and the product in consumer’s
mind. This involves tapping the “strong tie networks” of the potential customer. This concept is applicable
in the case study of Solae’s Soybean product and the strategy of conducting community events.
 Growth and consolidation: This steps builds on with the upcoming of commercial product targeted to the
consumer who has been all through the seeding and base building process; plus the “strong tie network” of
the consumer which trusts him.
These social and economic considerations stress on the fact that no two market is the same. Along with
technical considerations, it’s important to know the end users who’re going to use and benefit from that
technology. Right from product placement (fixed shop which stresses on the importance of relationship over
transactions) to people’s employment to product packaging; it’s important to understand that any BOP market
poses a no “one size fits all” contemplation.
2.2 Technical considerations
2.2.1 Current State of Makapads Production
Currently, Makapads are produced by Technology for Tomorrow Ltd. In the following steps:
procuring Papyrus from water bodies, transporting the material to manufacturing plant, separating outer
shell from inner pulp and chopping the pulp into small pieces, crushing and mixing pulp with recyclable
paper and water, drying the mixture under direct sunlight to form sheets, cutting sheets into shape of pads
after drying, packaging sheet in napkins (outer layer) using a solar-powered lamination machine and finally
packaging the Makapad followed by UV purification. These steps present two major concerns, namely,
dependence on sunlight for drying and involvement of electric energy to run manufacturing equipment. Both
the concerns need to be addressed such that the production capability could be increased and the business
model could be scaled. To address these concerns, we looked into using the outer layer of papyrus, which is
a useless by-product in the production of Makapads. This is generated in good amount as will scale up as the
production scales.
Even though, Makapads aren’t manufactured using energy from biomass, there are many industrial settings
in Uganda where it is used. In sub-Saharan Africa and specifically Uganda, traditional stoves that utilize
solid fuels like animal dung, coal and wood have long been used. Recently, the government and many NGOs
are making it possible for improved biomass stoves to replace traditional ones. The status of biomass
conversion technologies is mostly limited to this small-scale level right now. On a larger scale, only a few
known companies are utilizing biomass gasification.
Muzizi Tea Estates is a company that is using a GAS 250 gasifier (Ankur Scientific, India). They use
eucalyptus wood as feedstock and generate steam to dry black tea. Paramount Dairies, Ltd. is another
company utilizing gasification technology in Uganda, using the fuel gas from TLUD Gasifier Heat
Exchanger Prototype II as heat energy in order to pasteurize their milk [4].
The use of mixed or alternative feedstock is much less common, however, it is gaining tract throughout the
world. In Africa, deforestation is increasingly becoming a concern, as a result of an increase in population.
This, combined with an increase in demand for bioenergy, means that this improved method for biomass
gasification has potential for implementation. In Uganda, a few different known feedstocks have been
implemented, including tea, corncobs and bagasse from sugarcane.

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A group which also works in collaboration with Makerere University, the Pamoja Cleantech [5], has been
successful in installing and maintaining gasifiers that run on corncobs, as well as other agricultural waste
including coffee husks, rice husks and grounds nuts shells. They are operating All Power Lab’s GEK
(Gasifier Experimenter’s Kit) Power Pallet (10 and 20 kW) and Husk Power (30 kW). The energy generated
is used to power a corn flour mill. Additionally, they have been able to work with the local energy
companies and have provided economic opportunities at a base of pyramid market, just as we hope to do.
This research is focused on the possibility of incorporating papyrus husk as a feedstock for gasification.
Using the outer shell of the papyrus is of interest because it utilizes a waste material from the sanitation pad
production process that would be thrown out otherwise. Additionally, using this material contributes to the
decrease of deforestation, as it does not require trees to be harvested for wood.
2.2.2 Gasification v/s Biomass Torrefaction
A fundamental approach to use the energy potential in the papyrus waste is to do combustion. But direction
combustion isn’t a viable option due to the greenhouse gases that are released on burning. Therefore, I went
through the process of gasification; which is restricted oxidation of fuel-mass and found that it will be
advantageous over normal combustion of papyrus waste due to the following two reasons:
a. It provides emission control. It is easier to separate the SOx and CO2 gas from the mixture obtained
after gasification because it comes out at a higher temperature and pressure than the exhaust of combustion.
b. It can be used for higher temperature heating processes or could be used to generate electricity using
generators (giving more efficiency) and could also be stored in fuel cells as a major component of syngas is
hydrogen.
Biomass gasification is a thermal energy conversion process that takes a feedstock material and converts it
into fuel gas in a chamber and with an agent for controlled oxidation, like air. This fuel gas can then be used
for heat or converted to electricity. Unlike the burning of fossil fuels, using biomass is considered renewable
because the biomass that is burned can easily be replaced within our lifetimes, and net-zero because the
energy generated as output through the process cancels out the energy needed for input.
Gasification types can be classified and sub-classified based on their oxidising medium (pure O, steam or
air) and the “bed” upon which gasification takes place. There are 3 main types: fixed (moving) bed,
fluidized bed and entrained flow bed. While fluidized and entrained flow generally occur in larger scale,
industrial plants, fixed bed is the most economically sound for small-scale gasifiers, especially in developing
countries. Essentially, the oxidising medium moves the fuel through the chamber, and allows it to be
supported on a grate. Fixed bed can further be classified into 3 main groups based on the direction of flow of
the oxidising medium and the ultimate outflow of the gas: updraft, downdraft and cross draft. Updraft
describes gasifiers that input producer gas from the bottom of the chamber, with biomass material falling
from the top. The gas rises and comes into contact with the biomass in order to produce the output gas which
rises an exits at the top. Downdraft gasifiers are those in which the biomass material is inputted from the top
of the chamber and moves parallel to the gas, which is finally outputted from the bottom of the chamber [6].
Wood gasifiers have been in existence since World War II, and have been a consistent source of energy in
emergency situations, such as the oil crisis. Even now, wood gasification is commonly presented as an
alternative form of energy, and is used by many individuals on a small scale as well as in industrial plants.
Another important viable option other than using gasification over combustion that I encountered was bio
char production using torrefaction. Fig. 1 shows a model for gasification that could be used for drying
process and Fig. 2 shows a commercially viable bio char (solid bio coal) production system.

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Fig. 1. A viable gasification model
Fig. 2. Commercially prevalent Bio Char production system

9. Page 8 of 16
The major difference between both the processes, pertaining to our focus is that gasification requires a
controlled combustion (with limited oxygen) at about >700 degrees C [7-8], whereas bio char production
needs optimal temperature between 400-500o
C to make 60% of bio char (solid coal) and 0% of syngas.
Also, filtered syngas (4.7 MJ/kg) has lower calorific value over CO2 containing bio coal (18-31 MJ/kg)
[9-10]. But, even though biochar production system (using pyrolysis) is done at a lower temperature than
syngas production (700-1500 degrees C); it’s mostly used to provide manure to soil as it reduces nitrous
oxide emissions and increases methane intake, which is over 20 times more effective in trapping heat in the
atmosphere than CO2. As far as bio-coal for producing electricity is concerned, it’s mostly done using
thermoelectric materials. In the following case study taken from Uganda, people are using Biochar stoves
along with thermoelectric materials to charge their phones while burning biochar [11]. This case presents
that biocoal needs to be burnt to generate electricity using thermoelectric semiconductors. But, on further
inspection and discussion with Prof. Kevin Pipe (an expert in the field of thermoelectric materials); I found
that it’s not efficient both on technical and especially on economic grounds, to product energy from
thermoelectric materials at this scale. Whereas, gasification seems to be a scalable and feasible way to
harness the energy in papyrus waste.
2.2.3 Raw Material and its properties
The raw material for the gasification process is the outer layer of papyrus and the amount of material from
sheets (produced for making pads) left after cutting the pads out of it. The outer payer of papyrus weed
counts as the majority of the raw material. Therefore, I’ll be focusing on it throughout this section. Two of
the important properties of the raw biomass input for gasifiers are, namely, their moisture content (% per
weight) and calorific value (MJ/kg) [12]. The nominal values for these parameters are 20-25% and 12-15
MJ/ kg; which is generally the case with wood pallets used as raw materials [13].
Looking into papyrus outer layer, there’s no source of information found which gives a clear estimate of the
calorific value of Papyrus’s outer layer. To test it using Bomb Calorimeter, I got two stems of Papyrus
including its umbels and culms from Matthaei Botanical Gardens of University of Michigan. Next step was
to find the Bomb Calorimeter. Eventually, after finding it at Dr. Boehman’s lab, I went on with the test of
the sample, as shown in Fig. 3; using Parr Instrument Company’s 1341 Plain Jacket Bomb Calorimeter [14].
The test was unsuccessful as there was no combustion (as seen in Fig. 4; there’s no change in temperature
even after combustion inside the bomb) taking place inside the calorimeter after numerous testing. This
might have happened due to the semi solid, rather than liquid nature of test sample of papyrus material.

10. Page 9 of 16
Fig. 3 (a.) Specimen of Papyrus, to be placed in Bomb Calorimeter (b.) Bomb Calorimeter with data
acquisition system (c.) Temperature difference went unnoticed even after combustion
Fig. 4 There’s no difference found in temperature even after combustion in Bomb Calorimeter
a c
b

11. Page 10 of 16
Data from sources [15-17] suggest that the calorific value of Papyrus is 15-16 MJ/ kg. But, this doesn’t give
an estimate for the calorific value of outer layer of papyrus. Estimates obtained from a database of biomass
materials [18] tell that the calorific value of Bamboo culms and water Hyacinth are 13.86 and 11.93 MJ/ kg
respectively for 25% moisture content (wt%). These values can give a good approximation to the value of
Papyrus culms as Water Hyacinth also grows in water and is used for making furniture [19]; a similar
purpose for which Papyrus culms are used.
Therefore, at this point, the best estimate one could get from the available resources is that the calorific
value for outer layer of Papyrus is between 10-14 MJ/ kg for a moisture content of 20-25%.
3. Gasifier Selection and Design
Gasification is a series of five chemical processes all occurring in sealed chamber where the producer gas is
generated. These processes are: (1) drying, (2) pyrolysis, (3) combustion, (4) tar cracking and (5) reduction.
Once the gas is produced, it is cooled and filtered to result in gas that can be used for heat or electricity.
First, the drying process starts with heat in the chamber drying the biomass. In order for the biomass to
participate in pyrolysis and combustion, it must be below a certain moisture content. Pyrolysis is the process
in which biomass is heated in the absence of oxygen, burning the volatile gases. This results in a more
concentrated form of carbon, or char. Next, combustion takes place in which the char is burned to create
CO2 and H2O gases. Tar cracking allows liquid tar that is created in the process to be converted into useful
gases. Finally, reduction allows CO2 and H2O to form CO and H2 gases which are the producer gases, or
“syngas” that can be used to generate heat or electricity. After gasification, the gases undergo cooling and
filtration before they are ready to be utilized.
3.1 Gasifier Selection: FEMA v/s Imbert Design
Gasification is a complex process which includes thermal, chemical and gas flow as competing physical
phenomena. Different gasifiers designs are based on the trade-offs in these phenomena. Two major types of
gasifiers are updraft and downdraft gasifiers. Updraft gasifiers follows an ideal thermal relationship, i.e. it
transfers energy from combustion to reduction to pyrolysis and to drying. This order keep the flow of heat
from higher to lower temperatures. Even though this gasifier thermally efficient, it adds more tar to the
producer gas as the gas moves outside the gasifier via the section where pyrolysis takes place. Therefore,
downdraft gasifiers is preferred which has a drying chamber at the top, followed by Pyrolysis, Combustion
and Reduction chambers (moving from top to bottom). This doesn’t pollute the gas which moves out of the
gasifier as the gas moves out from the bottom of the gasifier after production.
Under downdraft gasifiers, there are two main designs; as far as our application is concerned. First one is
called FEMA gasifier. It’s one of the most basic design for a wood­gas or producer gas generator. This
gasifier was developed with a use for emergency purposes and is known for one of its drawback of having
high tar residue in the producer gas produced. The other design I looked at was Imbert gasifier. This design
of gasifier was invented just before mid-19th century and was put into mass production during World War II
as the gasifier helped many people prevent starvation. For our gasifier, we have chosen the Imbert
(downdraft, constricted hearth) design. In the Imbert gasifier, the feedstock is loaded in from the top, where
it is held in a storage drum, covered with a spring loaded lid [20]. The spring loaded lid acts as a safety valve
so that if pressure builds up in the chamber, it can release to relieve some of the pressure. The feedstock
travels down the chamber, where heat allows it to dry and take part in pyrolysis (fragmentation of biomass
into char coal and tar. The air that moves through the gasifier is pulled through using suction from an
engine. A set of air nozzles around the chamber inject air at the biomass, allowing most of it to combust.
This air nozzle zone is also where the original fuel is ignited in order to start the gasification process.
Underneath the air nozzles is the constricted hearth zone. The constricted hearth allows the rate of
gasification to be self-regulated by the fuel in the chamber. For example, if there is not enough charcoal at
the air nozzles, more wood is allowed through from the storage drum, and it is burned to restore the
charcoal. If there is too much charcoal, and its level rises above that of the nozzles and gets burned [21]. For
this reason, it is a much safer option than the FEMA gasifier, which requires the charcoal levels to be
monitored periodically. Secondly, the constricted hearth allows for improved insulation which prevents the
build-up of too much tar, which is a problem with other gasifiers. Therefore, as Imbert gasifier is known to

12. Page 11 of 16
produce lesser amount of tar gas and produces a much cleaner gas; which is many a times burnt directly to
generate heat [22]; Imbert gasifier is considered for our problem statement.
3.2 Design of Imbert Gasifier
As discussed in previous section, Imbert Gasifier has a constricted hearth for combustion which helps the
biomass inside the gasifier to move. This gasifier, as shown schematically in Fig. 5, has the following
processes going on from top to bottom. This constricted hearth is present in the combustion zone.
Fig. 5 Schematic Diagram for Downdraft Gasifier
Moving ahead with the gas, the syn-gas is transferred to the cooling chamber followed by filtration.
The schematic diagram in Fig. 6 shows the Imbert design gasifiers used during World War II.
SYN GAS
DRYING
COMBUSTION
PYROLYSIS
REDUCTION
ASH
DRY BIOMASS
AIRAIR

13. Page 12 of 16
Fig. 6 Diagram of Imbert design gasifiers used during World War II
Apart from this, there are two major redesigns made in the current times to the aforementioned design.
These are as follows:
a. Convective heat transfer between exiting syn-gas and incoming air:
As the producer gas (syn gas) moves out of the gasifier, it has a temperature of 250-300 degree Celsius. As
this high temperature is not of any use for the gas; which needs to undergo filtration, the heat in this goes
waste during a separate cooling process. In this cooling process, which takes place just after the exit of gas
from gasifier, involves a chamber with a cyclone-type rotor which takes away tar particles and also, helps in
cooling of the gas. Therefore, instead of wasting the heat energy in the exiting gas, it could be used to heat
the air entering the combustion chamber. By doing so, less amount of work will be needed by the
combustion chamber to heat the incoming air.
b. Using the heated gas in drying process
The same gas when heats up the incoming air, still has a temperature of 200 degree Celsius. As the gas still
has a reasonable temperature, its potential is used to heat the wood mass which is entering the gasifier. This
helps in drying the biomass and thereby, reducing its moisture content; which has a negative impact on the
efficiency of the combustion chamber and thus, gasifier.
Fig. 7 shows both the design features, applied to a downdraft (Imbert here) gasifier.

14. Page 13 of 16
Fig. 7 Redesigns in existing Imbert gasifier to use heat of syn gas
Moving further, the inspiration for these designs were obtained from All Power Labs’s educational platform
[23]. The design for the Imbert gasifier for a 40 Nm3
/h maximum power output is given in Fig. 8 below.
HEATTRANSFERFROMGASTOAIR
HEATTRANSFERFROM
GASTOBIOMASS
GAS MOVING FOR FILTRATION
AUGER SPIRAL TO MOVE
BIOMASS
IMBERT GASIFIER
AIR IN
SYN GAS OUT

15. Page 14 of 16
Fig. 8 Imbert Gasifier Design for 40 Nm3
/h plant
4. Further Work
Moving ahead, following steps need to be taken to make the Imbert Gasifier that needs to be functional with
outer layer of Papyrus as its biomass:
a. Find the exact calorific value of outer layer of Papyrus. If the calorific value of the outer layer of
Papyrus is low, either the raw biomass material will need to be changed or the process (gasification)
for harvesting the energy.
b. Simulate gasification process for the Imbert design of the gasifier in a multiphysics simulation
package. I looked into some work done previously with gasification [24-27] and found that people
are mostly using ASPEN PLUS (including a master’s thesis on gasification using this software by
MIT [28]). Fortunately, University of Michigan has this software package installed in CAEN
computers. Therefore, it won’t be a problem to work on it as far as availability is concerned. I have
found COMSOL Multiphysics a bit difficult to use without any error addition to the work but, that
still stands as an option. I’ll be looking into the simulation in more detail in future.
c. Prototyping the Imbert gasifier as per the design considerations obtained after simulation.
5. Conclusion
Increasing the production of Makapads requires a boost in the manufacturing capability of Technology for
Tomorrow Ltd. Also, this needs to be done in a cheap and sustainable way such that it doesn’t have an
adverse impact on the local community and its social and economic rubric. One way to do this is by using

16. Page 15 of 16
the outer layer of Papyrus, which isn’t used for making Makapads. This outer layer could be fed as a
biomass in a gasifier to produce heat energy which could be used to dry the sheets of mixture of papyrus and
paper such that the dependency on drying under sunlight is exterminated. First of all, the biomass needs to
have a reasonable energy content of about 15 MJ/ kg such that it could be used for gasification. It’s been
estimated that the outer layer of papyrus (20-25% by wt.) might have a calorific value between 10-14 MJ/
kg. Also, the gasifier that could serve this purpose efficiently is Imbert Type (Downdraft) gasifier.
A design for the 40 Nm3
/h downdraft gasifier is presented in the report which could be used for further
research work and simulation.
6. References
[1] WHO and UNICEF. (2013). Progress on sanitation and drinking-water – 2013 update. Geneva, WHO.
http://www.who.int/iris/bitstream/10665/81245/1/9789241505390_eng.pdf?ua=1
[2] Times of India (January 23, 2011). 70% can't afford sanitary napkins, reveals study.
http://timesofindia.indiatimes.com/india/70-cant-afford-sanitary-napkins-reveals-
study/articleshow/7344998.cms. Retrieved 2014-08-25
[3] “Next General Business Strategies for the Base of the Pyramid” by Prof. Ted London and Stuart L. Hart:
https://drive.google.com/file/d/0Bw2WF0CVsfPnTG1GRFhfQk5GejQ/view?usp=sharing
[4] Paramount Cheese (Case Study). http://www.paramountcheese.com/projects.htm
[5] Pamoja Cleantech (Working in collaboration with Makerere University).
http://www.pamojacleantech.com/
[6] Biomass Gasification and Pyrolysis: Practical Design and Theory, P. Basu
http://store.elsevier.com/Biomass-Gasification-Pyrolysis-and-Torrefaction/Prabir-Basu/isbn-
9780123965431/
[7] Advantage and efficiency of gasification.
http://www.netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/clean-power
[8] Gasification.
http://www.netl.doe.gov/File%20Library/Research/Coal/energy%20systems/gasification/gasifipedia/in
dex.html
[9] Calorific value of biochar. http://pacificpyrolysis.com/agrichar.html
[10] Calorific value of syngas. http://en.wikipedia.org/wiki/Syngas
[11] Using bamboos for stoves in Uganda. http://www.biochar-international.org/Uganda_Stoves
[12] List of biomass and their productivity for a commercial gasifier: http://www.allpowerlabs.com/wp-
content/uploads/2014/05/APL_2014catalog_5_13_14_small.pdf
[13] Typical calorific values of fuels:
http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,20041&_dad=portal&_schema=POR
TAL
[14] Parr Instrument Company: Bomb Calorimeter.
https://drive.google.com/file/d/0Bw2WF0CVsfPnR0xWMHhjblVIV3M/view?usp=sharing
[15] Biomass production of papyrus (Cyperus papyrus) in constructed wetland treating low-strength
domestic wastewater. P. Thaneeya, P. Chongchin.
http://www.thaiscience.info/Article%20for%20ThaiScience/Article/2/Ts-
2%20biomass%20production%20of%20papyrus%20%28cyperus%20papyrus%29%20in%20construct
ed%20wetland%20treating%20low-strength%20domestic%20wastewater.pdf
[16] Calorific value of Papyrus briquetts (Lehrafuel). http://www.lehrafuel.com/briquetts-calorific-
value.html
[17] Milk Pasteurization system with TLUD stove as a combustion device.
http://www.drtlud.com/wp-content/uploads/2012/09/Prototype-I-system-specs.pdf

17. Page 16 of 16
[18] Database of all the biomasses: http://www.ecn.nl/phyllis2/
[19] Water hyacinth turns into money-spinner for furniture maker.
http://www.businessdailyafrica.com/Water-hyacinth-turns-into-money-spinner-for-furniture-maker-/-
/1248928/1308390/-/sonsfz/-/index.html
[20] Construction of a Simplified Wood Gas Generator for Fueling Internal Combustion Engines in a
Petroleum Emergency. http://www.build-a-gasifier.com/PDF/FEMA_emergency_gasifier.pdf
[21] Handbook of Biomass Downdraft Gasifier Engine Systems.
http://www.nrel.gov/docs/legosti/old/3022.pdf
[22] Imbert v/s FEMA gasifier. http://www.miniwoodgas.com/miniwoodgas_004.htm
[23] All PowerLabs Resources. http://www.allpowerlabs.org/gasification/resources/
[24] Simulation of biomass gasification in fluidized bed reactor using ASPEN PLUS.
http://www.sciencedirect.com/science/article/pii/S0961953408000688
[25] Simulations and modeling of biomass gasification processes.
http://dspace.mit.edu/handle/1721.1/31178#files-area
[26] Two-Dimensional Computational Fluid Dynamics Simulation of Biomass Gasification in Downdraft
Fixed-Bed Gasifier with Highly Preheated Air and Steam.
http://pubs.acs.org/doi/abs/10.1021/ef4003704
[27] Simulation of a scaled up gasifier. http://www.chemrec.se/Simulation_of_scaled-up_gasifier.aspx
[28] Simulations and modeling of biomass gasification processes.
http://dspace.mit.edu/handle/1721.1/31178#files-area
7. Appendix
1. Notes from Gasifier 101 Lecture Series: http://www.miniwoodgas.com/miniwoodgas_007.htm
2. Questions to be asked from Dr. Moses:
a) What is amount of bio-waste produced per (kg/tonne of) useful sheets of papyrus mixture? This will
drive the amount of energy that could be produced.
b) How much energy does the solar panel provide so that we can use it to create steam s.t. a temperature
of 700o
C could be produced in the gasifier chamber? It’s noted that modern pyrolysis plants can use
the syngas created by the pyrolysis process and output 3–9 times the amount of energy required to
run.
c) What is the calorific value of papyrus waste? This is really important for driving the whole energy
aspect of the system. We can do experiments to find it.
d) Do we really need to make our own gasifier instead of using commercial ones? Gasifiers in the
market are capable of using different forms of bio-wastes. I don’t think papyrus will have a
significantly low calorific value such that we will need to make a separate gasifier system for it.
e) How moist is the bio-waste produced? Dryer the waste, lesser the amount of energy required to dry
the papyrus mixture.
f) What is the weight of a bunch (say dozen) of wet papyrus sheets which require drying?
g) Also, I need to understand one basic process. How does the manufacturer make sheets of papyrus
from the slurry made using the mixture? Is drying under sun involved in forming it? If yes, then how
can that be incorporated in drying using gasifier?
h) Later on, we will also need the density, calorific value and composition of the bio waste produced.
This is required to calculate the energy flow during the whole process.