WELCOME

1. INDUSTRIAL BOILERS CUSTOMIZED ENVIRONMENTAL TRAINING WELCOME

2. INSTRUCTOR Insert Instructor Name Here

3. OBJECTIVES • 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.

4. GOALS • 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.

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

7. OVERVIEW 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.

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 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 CLEAN AIR ACT

10. 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 APPLICABLE REGULATIONS

11. 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 INDUSTRIAL BOILERS

12. 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 BOILER SIZES

13. 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 HOW NOx IS FORMED

14. 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 HOW NOx IS FORMED

15. 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. PARAMETERS AFFECTING NOx

16. 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. PARAMETERS AFFECTING NOx

17. 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. FACTORS AFFECTING NOx

18. 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 BOILER DESIGN TYPE

19. 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 BOILER DESIGN TYPE

20. 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 BOILER DESIGN TYPE

21. 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 BOILER DESIGN TYPE

22. 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 BOILER DESIGN TYPE

23. 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 BOILER DESIGN TYPE

24. 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 FUEL CHARACTERISTICS

25. 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 FUEL CHARACTERISTICS

26. 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 FUEL CHARACTERISTICS

27. 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 FUEL CHARACTERISTICS

28. 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 FUEL CHARACTERISTICS

29. 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 BOILER HEAT RELEASE RATE

30. 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 BOILER OPERATIONAL FACTORS

31. 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 BOILER OPERATIONAL FACTORS

32. 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 CONTROLS

33. 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 CONTROLS

34. 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 CONTROLS

35. 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. CONTROLS

36. 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 CONTROLS

37. 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 CARBON MONOXIDE (CO)

38. 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 OTHER AIR POLLUTANTS

39. 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 OTHER AIR POLLUTANTS

40. 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 OTHER AIR POLLUTANTS

41. 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. SOLID WASTE

42. 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 WATER USE AND WASTEWATER

43. 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 HAZARDOUS WASTE

44. 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 BURNING HAZARDOUS WASTE

45. 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. BURNING HAZARDOUS WASTE

46. 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 BURNING HAZARDOUS WASTE

47. 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. BURNING HAZARDOUS WASTE

48. 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. ASBESTOS

49. 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 BOILER SAFETY PRECAUTIONS

50. 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. BOILER SAFETY PRECAUTIONS