Design & Analysis of industrial Boilers

1. WELCOME
INDUSTRIAL BOILERS
Design & Analysis
Easy explained step by step

2. INSTRUCTOR
Engr. Hashim Hasnain Hadi

3.  Define Industrial Boiler Size.
 Discuss How Nitrogen Oxide (NOx) is Formed.
 Discuss Factors Affecting NOx.
 Discuss Boiler Operational Factors.
 Discuss NOx Controls.
 Discuss Other Environmental Considerations Concerning
Boilers.
 Discuss Burning Hazardous Waste in Boilers.
 Discuss Boiler Safety Precautions.
 Outline Safety and Environmental Inspection Items.
 Discuss Monitoring Requirements.
 Discuss Use of Contractors.
OBJECTIVES

4.  Be Familiar With Records to Maintain.
 Understand What Is Considered an Industrial Boiler.
 Understand How Nitrogen Oxide (NOx) is Formed.
 Understand the Factors Affecting NOx.
 Be Familiar With Boiler Operational Factors.
 Understand the Different NOx Controls.
 Be Familiar With Other Environmental Considerations
Concerning Boilers.
 Understand the Requirements for Burning Hazardous Wastes.
 Be Familiar With Boiler Safety Precautions.
 Be Familiar With Safety and Environmental Inspection Items.
 Be Familiar With Monitoring Requirements.
GOALS

5. BACKGROUND
 In 1999, there were 5,489,423 tons of Nitrogen Oxide
(NOx) emitted into the atmosphere by industrial boilers.
NOx is instrumental in smog and acid rain formation
 On November 3, 1999, the Justice Department filed
seven lawsuits against electric utilities in the Midwest and
South charging them with violations of their NOx boiler
emissions
 43% of all boilers are subject to Nitrogen Oxide (NOx)
emission limits

6.  Supervisors
 Facility Engineers
 Maintenance Personnel
 Department Managers
 Building Occupants
 Process Specialists
 Environmental and Safety Committees
LEARNERS

7. The goal of this course is to provide supervisors
with the tools needed to properly manage industrial
boilers. It recommends practical, actions that can be
carried out by facility management, maintenance
personnel and building occupants. The course will
help you to integrate good industrial boiler
management activities into your existing
organization and identify which of your staff have
the necessary skills to carry out those activities.
OVERVIEW

8. WHAT THIS COURSE DOES NOT DO
The course is not intended to provide information to
repair industrials boilers or to install or repair
monitoring equipment or control devices. These
specialties required training beyond the intended
scope of this course. Where this expertise is
needed, outside assistance should be solicited.

9. CLEAN AIR ACT
 Clean Air Act Amendments (CAAA) of 1990, amended Title I of
the Clean Air Act (CAA) to address ozone nonattainment areas
 Stationary sources that emit oxides of nitrogen (NOx) which
emit or have the potential to emit 25 tons per year or more of such
air pollutant

10. APPLICABLE REGULATIONS
 40 CFR 63 – National Emission Standards For Hazardous Air
Pollutants For Source Categories
 40 CFR266-- Subpart H--Hazardous Waste Burned in Boilers and
Industrial Furnaces
 40 CFR 76 – Acid Rain Nitrogen Oxides Emission Reduction
Program

11. INDUSTRIAL BOILERS
 Industrial boilers have been identified as a category that emits
more than 25 tons of oxides of nitrogen (NOx) per year
 Boilers include steam and hot water generators with heat input
capacities from 0.4 to 1,500 MMBtu/hr (0.11 to 440 MWt).
 Primary fuels include coal, oil, and natural gas
 Other fuels include a variety of industrial, municipal, and
agricultural waste fuels

12. BOILER SIZES
 Industrial boilers generally have heat input capacities ranging
from 10 to 250 MMBtu/hr (2.9 to 73 MWt). The leading user
industries of industrial boilers, ranked by aggregate steaming
capacity, are the paper products, chemical, food, and the
petroleum industries
 Those industrial boilers with heat input greater than 250
MMBtu/hr (73 MWt) are generally similar to utility boilers
 Boilers with heat input capacities less than 10 MMBtu/hr (2.9
MWt) are generally classified as commercial/institutional units

13. HOW NOx IS FORMED
 NOx is a high-temperature byproduct of the combustion of fuels
with air
 NOx formation in flames has two principal sources
1. Thermal NOx is that fraction of total NOx that results from the
high-temperature reaction between the nitrogen and oxygen in the
combustion air
The rate of thermal Nox formation varies exponentially with peak
combustion temperature and oxygen concentration
 When low-nitrogen fuels such as natural gas, higher grade fuel
oils, and some nonfossil fuels are used, nearly all the NOx
generated is thermal NOx

14. HOW NOx IS FORMED
2. Fuel NOx is that fraction of total NOx
that results from the conversion of
organic-bound nitrogen in the fuel to NOx
 When coal, low-grade fuel oils, and
some organic wastes are burned, fuel NOx
generally becomes more of a factor
because of the higher levels of fuel-bound
nitrogen available

15. PARAMETERS AFFECTING NOx
Principal among these are:
 The heat release rates and absorption profiles in the furnace
 Fuel feed mechanisms
 Combustion air distribution
 Boiler operating loads
For example, steam pressure and temperature requirements may
mandate a certain heat release rate and heat absorption profile in the
furnace which changes with the load of the boiler.

16. PARAMETERS AFFECTING NOx
 Solid fuels can be introduced into the furnace
in several ways, each influencing the rate of
mixing with combustion air and the peak
combustion temperature
 These parameters are very unit specific and
vary according to the design type and application
of each individual boiler
 NOx emissions from boilers tend to be highly
variable.

17. FACTORS AFFECTING NOx
The ranges in baseline NOx emissions for boilers
are due to several factors including:
 Boiler design
 Fuel type
 Boiler operation
These factors usually influence baseline NOx in
combination with each other, and often to
different degrees depending on the particular
boiler unit.

18. BOILER DESIGN TYPE
 The firing type of the
boiler influences the overall
NOx emission level
 Even within a particular
type of boiler, other design
details may influence
baseline NOx

19. BOILER DESIGN TYPE
For Pulverized Coal:
Boiler Type Average lb of NOx / MM Btu
Tangential 0.61
Wall-Fired 0.69
Cyclone 1.12
 Low NOx Burners, Natural Gas Reburning, and Low NOx Burners
with Staged Combustion Air are effective in controlling NOx in these
units

20. BOILER DESIGN TYPE
For Coal:
Boiler Type Average lb of NOx / MM Btu
Overfeed Stoker 0.29
Circulating Fluidized Bed Combustion (FBC) 0.31
Bubbling FBC 0.32
Underfeed Stoker 0.39
Spreader Stoker 0.53
 Air staging in coal-fired FBC boilers is very effective in reducing
NOx from these units

21. BOILER DESIGN TYPE
For Residual Oil:
Boiler Type Average lb of NOx / MM Btu
Firetube 0.31
Watertube (10-100 MM Btu/hr) 0.36
Watertube (>100 MM Btu/hr) 0.38
 Low NOx Burners, Flue Gas Recirculation, and Staged Combustion
Air have shown some reduction in NOx for residual oil

22. BOILER DESIGN TYPE
For Distillate Oil:
Boiler Type Average lb of NOx / MM Btu
Watertube (10-100 MM Btu/hr) 0.13
Firetube 0.17
Watertube (>100 MM Btu/hr) 0.21
 Low NOx Burners, Flue Gas Recirculation, and the combination of
Low NOx Burners with Flue Gas Recirculation are used to control
Distillate Oil NOx

23. BOILER DESIGN TYPE
For Natural Gas:
Boiler Type Average lb of NOx / MM Btu
Firetube 0.10
Thermally Enhanced Oil Recovery
(TEOR) Steam Generator 0.12
Watertube (10-100 MM Btu/hr) 0.14
Watertube (>100 MM Btu/hr) 0.26
 Low NOx Burners, Flue Gas Recirculation, and Staged Combustion
Air and combinations of these methods are all effective in reducing
NOx for natural gas

24. FUEL CHARACTERISTICS
 Boiler baseline NOx emissions are highly influenced by the
properties of the fuels burned
 Among each of fuel types, emissions will depend on highly
variable factors such as fuel grade and fuel source
 In particular, studies have shown that fuel nitrogen content —
and for coal the oxygen content and the ratio of fixed carbon to
volatile matter — are key factors influencing NOx formation

25. FUEL CHARACTERISTICS
Nitrogen Content of Fuels
The following table gives ranges of nitrogen content for different
fuels:
Fuel % by Weight
Coal .8 – 3.5
Residual Oil .36
Distillate Oil <0.01
Natural Gas 0 – 12.9

26. FUEL CHARACTERISTICS
Sulfur
Sulfur can combine with oxygen and water to form Sulfuric Acid,
H2SO4
Fuel % of Sulfur
Coal 1-4
Residual Oil 1.3
Distillate Oil .72
Natural Gas <0.001
Although lower sulfur content generally means lower nitrogen,
there is no apparent direct relationship between these two fuel oil
parameters

27. FUEL CHARACTERISTICS
Fuel Ratio
 Fuel ratio is defined as the ratio of a coal's fixed carbon to
volatile matter
 Under unstaged combustion conditions, lower fuel ratios (i.e.
higher volatile content of the coal) correlate to higher levels of
NOx, because with higher volatile content coals, greater
amounts of volatile nitrogen are released in the high
temperature zone of the flame where sufficient oxygen is
present to form NOx
 Firing coal with high volatile content and lower fixed carbon
generally results in less solid carbon to be burned out in the
post-flame gases, meaning that the coal can be fired at lower
excess air before combustible losses became a problem

28. FUEL CHARACTERISTICS
Moisture
 Moisture content plays an important role in the
formation of uncombustible emissions in Municipal
Solid Waste boilers
 Non-combustible content of Municipal Solid Waste
can range from 5 to 30 percent
 Moisture content of Municipal Solid Waste can
range from 5 to 50 percent
 Nitrogen contents of Municipal Solid Waste can
range between 0.2 and 1.0 percent

29. BOILER HEAT RELEASE RATE
 Boiler heat release rate per furnace area is another influential
variable affecting NOx formation
 As heat release rate increases, so does peak furnace
temperature and NOx formation
 Boiler heat release rate varies primarily with:
 Boiler firing type
 Primary fuel burned
 Operating load
 Boiler heat release rate per unit volume is often related to boiler
capacity

30. BOILER OPERATIONAL FACTORS
 Chief among these operational factors are the
amount of excess oxygen in the flue gases and the
combustion air temperature
 Excess oxygen refers to the oxygen concentration
in the stack gases, and is dependent on the amount
of excess air provided to the boiler for combustion
 Combustion air temperature, meanwhile, is
dependent on the degree of air preheat used before
the air is introduced into the furnace or burner
 Air preheat is usually used to increase furnace
thermal efficiency

31. BOILER OPERATIONAL FACTORS
 Operation on low excess oxygen or air is therefore considered a
fundamental part of good combustion management of boilers
 Many boilers are typically fired with excess oxygen levels which
are more than adequate to assure complete combustion and a
margin of safety
 Units often are operated at unnecessarily high excess oxygen
levels that result in unnecessarily high NOx emissions and losses in
efficiency
 The greater degree that the air is preheated, the higher the peak
combustion temperature and the higher the thermal NOx

32. CONTROLS
 Retrofitting existing generating units with low-NOx
burners is the most frequently chosen compliance
control because it is an economical way to limit the
formation of NOx
 Low-NOx burners control fuel and air mixing to create
larger and more branched flames, reduce peak flame
temperatures and lower the amount NOx formed
 The improved flame structure also improves burner
efficiency by reducing the amount of oxygen available in
the hottest part of the flame

33. CONTROLS
In principle, there are three stages in a conventional low-NOx burner:
1. Combustion - combustion occurs in a fuel-rich, oxygen-deficient
zone where the NOx is formed
2. Reduction - where hydrocarbons are formed and react with the
already formed NOx
3. Burnout - internal air staging completes the combustion. Additional
NOx formation occurs in the third stage, but it can be minimized by
an air-lean environment
Low-NOx burners can also be combined with overfire air
technologies to reduce NOx further

34. CONTROLS
Natural Gas Reburning
 Another combustion modification technique involves the staging
of fuel, rather than combustion air
 By injecting a portion of the total fuel input downstream of the
main combustion zone, hydrocarbon radicals created by the
reburning fuel will reduce NOx emission emitted by the primary fuel
 This reburning technique is best accomplished when the reburning
fuel is natural gas
 Application of these techniques on boilers has been limited to
some municipal solid waste (MSW) and coal-fired stokers

35. CONTROLS
Staged Combustion Air (SCA)
 A technique that reduces flame temperature and oxygen
availability by staging the amount of combustion air that is
introduced in the burner zone
 SCA can be accomplished by several means.
 For multiple burner boiler, the most practical approach is to take
certain burners out of service (BOOS) or biasing the fuel flow to
selected burners to obtain a similar air staging effect
 Generally, SCA is not considered viable for retrofit to packaged
boiler units due to installation difficulties.

36. CONTROLS
Flue Gas Recirculation (FGR)
 Involves recycling a portion of the combustion gases from the
stack to the boiler windbox
 These low oxygen combustion products, when mixed with
combustion air, lower the overall excess oxygen concentration and
act as a heat sink to lower the peak flame temperature and the
residence time at peak flame temperature
 These effects result in reduced thermal NOx formation.
 It has little effect on fuel NOx emissions
 FGR is currently being used on a number of watertube and firetube
boilers firing natural gas

37. CARBON MONOXIDE (CO)
 The CO emissions from boilers are normally near zero, with the
exception of a few boilers that have poor combustion air control or
burner problems
 Oil-fired units were found to have the lowest baseline CO
emissions than either coal- or gas-fired units
 CO emissions are generally caused by poor fuel-air mixing, flame
quenching, and low residence time at elevated temperatures
 In some furnace designs, CO emissions can also occur because of
furnace gas leaks between furnace tubes

38. OTHER AIR POLLUTANTS
 Other air pollution emissions that are a concern when NOx
controls are applied to boilers are: ammonia (NH) and nitrous oxide
(NO), unburned hydrocarbon (HC), particulate matter (PM), and air
toxic emissions
 Ammonia and NO emissions are associated with the use of the
Selective Non-Catalytic Reduction (SNCR) controls and with
Selective Catalytic Reduction controls to a lesser extent. With
either urea or ammonia hydroxide, unreacted ammonia emissions
escape the SNCR temperature window resulting in direct emissions
to the atmosphere

39. OTHER AIR POLLUTANTS
 Increases in HC, particulate matter (PM) and air toxic emissions
are primarily of concern with the application of combustion
modification controls
 HC emissions do not change when NOx controls are
implemented
 HC emissions are the result of poor combustion conditions such
as inefficient fuel-air mixing, low temperatures, and short residence
time
 These emissions are most often preceded by large increases in
CO, soot, and unburned carbon content
 By limiting CO, smoke and unburned carbon in the flyash, HC
emissions are also suppressed

40. OTHER AIR POLLUTANTS
Studies of industrial boilers and particulate matter (PM) reveal the
following trends:
 Low excess air reduced PM emissions on the order of 30 percent
 Staged combustion air increased PM by 20 to 95 percent
 Burner adjustments and tuning had no effect on PM
 Lower CO emission levels generally achieved with these
adjustments would tend to lower PM as well
 Flue gas recirculation resulted in an increase in PM from oil-fired
packaged boilers by 15 percent over baseline levels

41. SOLID WASTE
 NOx reduction techniques that have a potential
impact on the disposal of solid waste are combustion
controls for Pulverized Coal-fired boilers and flue gas
treatment systems for all applicable boilers
 Combustion controls for Pulverized Coal-fired boilers
are principally Low NOx Burners. These controls can
result in an increase in the carbon content of flyash
that can preclude its use in cement manufacturing.

42. WATER USE AND WASTEWATER
 The only increase in water use is
associated with the use of Water Injection
or Steam Injection and potentially with the
use of flue gas treatment NOx controls,
especially Selective Non-Catalytic
Reduction
 The amount of water used does often
not exceed 50 percent of the total fuel
input on a weight basis

43. HAZARDOUS WASTE
 Catalysts used in the Selective Catalytic Reduction process can
be hazardous
 Examples are vanadia and titania catalysts
 Many catalyst vendors recycle this material thus avoiding any
disposal problem for the user
 Some of the catalysts, especially those that use rare earth
material such as zeolites, are not hazardous and their disposal does
not present an adverse impact

44. BURNING HAZARDOUS WASTE
 40 CFR 266.100, Subpart H allows for
burning hazardous waste in industrial boilers
 Prior to burning hazardous waste in a
boiler, owner/operators must receive a permit
 The destruction of hazardous waste in a
boiler is considered treatment
 A hazardous waste analysis must be
performed prior to receiving a permit

45. BURNING HAZARDOUS WASTE
General Requirements – Fugitive emissions.
Fugitive emissions must be controlled by:
(A) Keeping the combustion zone totally sealed against fugitive
emissions; or
(B) Maintaining the combustion zone pressure lower than
atmospheric pressure; or
(C) An alternate means of control demonstrated to provide fugitive
emissions control equivalent to maintenance of combustion zone
pressure lower than atmospheric pressure.

46. BURNING HAZARDOUS WASTE
General Requirements – Automatic waste feed cutoff
 A boiler must be operated with a functioning system that
automatically cuts off the hazardous waste feed when operating
conditions deviate
 The permit limit for minimum combustion chamber temperature
must be maintained while hazardous waste or hazardous waste
residues remain in the combustion chamber
 Exhaust gases must be ducted to the air pollution control system
 Operating parameters for which permit limits are established
must continue to be monitored

47. BURNING HAZARDOUS WASTE
General Requirements – Changes
 A boiler must cease burning hazardous waste
when changes in combustion properties, or feed
rates of the hazardous waste, other fuels, or
industrial furnace feedstocks, or changes in the
boiler or industrial furnace design or operating
conditions deviate from the limits as specified in
the permit.

48. ASBESTOS
 Asbestos was used in fire brick and gunnite used for internal
insulation of boilers and other vessels
 Asbestos is dangerous when it becomes “friable”
 Asbestos materials are health hazards because:
•Inhaled asbestos fibers can be trapped in the lungs
•Inhaled asbestos fibers have been linked to cancerous cell growth
in the lungs
 If asbestos is in your older boiler, have workman alerted to its
presence. Any friable asbestos should be removed by qualified
workers.

49. BOILER SAFETY PRECAUTIONS
Safety Precautions
 An overheating boiler can quickly be identified by steam or a
mixture of steam and water being discharged at the safety relief valve
or from an open hot water faucet
 If this condition is found at a faucet, close the faucet
 Immediately shut down the water heater's source of heat
 Allow the water heater to cool naturally without the addition of
excess cold water

50. BOILER SAFETY PRECAUTIONS
An overheating boiler may exhibit the
following conditions:
1. A discharging safety relief valve.
2. Pressure and/or temperature readings
above the maximum allowed for the boiler.
3. Low or no water in boilers equipped with
water-level gage glasses.
4. Scorched or burning paint on the skin
casing.

51. BOILER SAFETY PRECAUTIONS
When a water heater or boiler is overheating, the
only safe intervention is to remove the heat
source by stopping the supply of fuel or air.
1. Do not try to relieve the pressure.
2. Do not add cool water into the vessel.
3. Do not try to cool the vessel with water.
Let the vessel cool down naturally. Get away
from the vessel. Call a qualified repair company.

52. SAFETY INSPECTION ITEMS
1. Exterior shell and/or insulation - Look for indications of
overheating
2. Leaks - Look for water on the floor or steam escaping
3. Flue gas leaks - Look for black dust (soot) around sheet-metal
joints
4. Controls - Look for open panels, covers, and signs of rewiring on
floor or bottom of panels
5. Electrical - Ensure that covers are installed on overlimit switches,
temperature sensors, and controls

53. SAFETY INSPECTION ITEMS
6. Safety valves - Ensure that a safety valve is installed with full-
sized discharge piping properly supported and directed to a point
of safe discharge
7. Fuel sources - Check for the ability to shut off the fuel source to
the vessel
8. Gauges - Make sure temperature and pressure gauges are
operational and are located for proper monitoring
9. Proper piping - Check for proper supports and allowance for
expansion and contraction
10. Operating certificate - Observe certificate noting last date of
inspection and expiration date when required

54. ENVIRONMENTAL INSPECTION
ITEMS
 Post a copy of the air operating permit near the boiler
 All boiler operators know how to operate the boiler within the
permit limits
 At the beginning of each shift, make sure the equipment is
operating properly
 Boiler operators should be familiar with the boiler’s operating
and maintenance manual
 Regular service should be performed on schedule and recorded
 Operating records and inspection records should be reviewed
regularly to ensure compliance

55. MONITORING REQUIREMENTS
 EPA’s Acid Rain Program has established special monitoring and
reporting requirements for all units over 25 megawatts and new
units under 25 megawatts that use fuel with a sulfur content
greater than .05 percent by weight
 The new units under 25 megawatts using clean fuels are required
to certify their eligibility for an exemption every five years
 All existing coal-fired units serving a generator greater than 25
megawatts and all new coal units must use CEM for SO2, NOx, flow,
and opacity.
 Units burning natural gas may determine SO2 mass emissions by
three ways

56. MONITORING REQUIREMENTS
Units burning oil may monitor SO2 mass
emissions by one of the following methods:
1. daily manual oil sampling and analysis plus
oil flow meter (to continuously monitor oil
usage)
2. sampling and analysis of diesel fuel oil as-
delivered plus oil flow meter
3. automatic continuous oil sampling plus oil
flow meter
4. SO2 and flow CEMs.

57. MONITORING REQUIREMENTS
 Gas-fired and oil-fired base-loaded units must use NOx CEMs.
 Gas-fired peaking units and oil-fired peaking units may either
estimate NOx emissions by using site-specific emission correlations
and periodic stack testing to verify continued representativeness of
the correlations, or use NOx CEMS
 All gas-fired units using natural gas for at least 90 percent of
their annual heat input and units burning diesel fuel oil are exempt
from opacity monitoring
 For CO2 all units can use either (1) a mass balance estimation, or
(2) CO2 CEMs, or (3) O2 CEMs in order to estimate CO2 emissions

58. MONITORING REQUIREMENTS
CEM systems include:
 An SO2 pollutant concentration monitor
 A NOx pollutant concentration monitor
 A volumetric flow monitor
 An opacity monitor
 A diluent gas (O2 or CO2) monitor
 A computer-based data acquisition and handling system (DAHS)
for recording and performing calculations with the data
CEM systems must be in continuous operation and be able to
sample, analyze, and record data at least every 15 minutes and
reduce flow data to 1-hour averages.

59. RECORDKEEPING
The CEM rule includes requirements for notification, recordkeeping,
and reporting for the Acid Rain Program, such as:
 Submission of monitoring plans
 Written notifications of monitor certification tests
 Report of certification test results in a "certification application“
 Recording and maintaining of hourly emissions data, flow data,
and other information
 Quarterly reports of emissions, flow, unit operation, and
monitoring performance data.

60. RECORDKEEPING
 The owner or operator also must report the
data in a standard electronic format available
through the Acid Rain Hotline
Unless otherwise specified by your
regulators or permit conditions, it is
recommended to keep these records for a
minimum of 3 years unless the boiler destroys
hazardous waste, then the records must be
kept through closure of the boiler

61.  Remember, You Control Your Facility or Area!
 Review Procedures With Them Before Starting the
Job!
 Ensure They Are Properly Trained!
 Determine Their Environmental Compliance Record!
 Determine Who Is in Charge of Their People!
 Determine How They Will Affect Your Facility’s
Environmental Compliance!
TIPS FOR USING CONTRACTORS

62. ELEMENTS OF A SUCCESSFUL
INDUSTRIAL BOILER PROGRAM
1. DETAILED WRITTEN INDUSTRIAL BOILER INSPECTION
GUIDELINES.
2. DETAILED WRITTEN INDUSTRIAL BOILER BEST MANAGEMENT
PRACTICES.
3. EXTENSIVE EMPLOYEE TRAINING PROGRAMS
4. PERIODIC REINFORCEMENT OF TRAINING
5. SUFFICIENT DISCIPLINE REGARDING IMPLEMENTATION
6. PERIODIC FOLLOW-UP

63. THE IMPORTANCE OF A
CLEAN ENVIRONMENT
“I would ask all of us to remember
that protecting our environment is
about protecting where we live and
how we live. Let us join together to
protect our health, our economy,
and our communities -- so all of us
and our children and our
grandchildren can enjoy a healthy
and a prosperous life.”
Carol Browner
Former
EPA
Administrator