NOx Emissions from Cement Mfg - US Environmental Protection ...

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ILC systems: In these systems, the fuel combustion in the calciner takes place in a mixture of the kiln exhaust gas and hot air from the cooler (tertiary air). Some of the nitrogen in the fuel reacts with NO from the kiln exhaust gas while another part reacts with oxygen to form NO. The result may be a net production or a net reduction of NO in the calciner. SLC systems: In these systems, the fuel combustion in the calciner takes place in pure hot air. In the case of oil firing, NO production in the calciner is negligible; but when using fuels containing fuel-bound nitrogen, up to 50 percent of the nitrogen compounds in the fuel may be converted into NO . The specific x NO production in an SLC calciner may be as high as 4 lb NO per x x ton of clinker as measured in a calciner fired with pet coke 1 which has a high nitrogen content and low volatile content. The NO in the calciner exhaust gas is added to the NO in the gas x x from the rotary kiln which leaves this type of kiln system without being reduced. When fired with solid fuels, SLC systems may therefore be expected to generate somewhat higher NO x emissions than the ILC systems. 1 4.2.3 Energy Efficiency of the Cement-Making Process Since the NO formation is directly related to the fuel x combustion, any reduction in the amount of fuel burned per unit amount of cement produced should reduce NO emissions per unit x amount of cement. Attempts to improve energy efficiency of the process by avoiding excessive clinker burning, utilizing waste heat effectively for preheating combustion air, coal, and raw mix is likely to reduce NO emissions. Improving heat transfer x between hot gases and solid materials, e.g., by chain systems, will improve energy efficiency. The newer preheater and precalciner kiln designs provide very efficient preheating and precalcining of the raw mix with intimate gas-solids contact in cyclone towers. New cement kiln constructions or renovations of older kilns thus predominantly involve precalciner designs for 4-14
their energy efficiency. The inherent energy efficiency of these kiln designs is likely to produce less NO emissions per unit x amount of clinker as compared to the long wet or dry kilns. 4.3 AVAILABLE DATA FOR UNCONTROLLED NO EMISSIONS FROM CEMENT x MANUFACTURING FACILITIES The four types of cement kilns discussed in the last section exhibit different combustion characteristics as well as energy efficiencies and heat requirements. The available NO emissions x data are therefore generally grouped by these cement kiln types. The PCA conducted a survey of the NO x and SO x emissions from the 11 cement industry in 1982. Results of that survey are shown in Figure 4-2 4-15
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EPA-453/R-94-004 ALTERNATIVE CONTRO
Page 3 and 4:
ALTERNATIVE CONTROL TECHNOLOGY DOCU
Page 5 and 6:
Chapter Page 4.1 MECHANISMS OF NO F
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TABLE OF CONTENTS (con.) Chapter Pa
Page 9 and 10: LIST OF TABLES Number Page 2-1 UNCO
Page 11 and 12: CHAPTER 1 INTRODUCTION Congress, in
Page 13 and 14: CHAPTER 2 SUMMARY This chapter pres
Page 15 and 16: 2.2 NO EMISSION CONTROL TECHNOLOGIE
Page 17 and 18: TABLE 2-2. ACHIEVABLE NO REDUCTIONS
Page 19 and 20: TABLE 2-4. CAPITAL AND ANNUAL COSTS
Page 21 and 22: TABLE 2-5. COST EFFECTIVENESS OF NO
Page 23 and 24: eductions ranged from 470 tons/year
Page 25 and 26: CHAPTER 3 INDUSTRY DESCRIPTION 3.1
Page 27 and 28: Type II. Moderate-heat-of-hardening
Page 29 and 30: 3 a TABLE 3-2. UNITED STATES CEMENT
Page 31 and 32: Figure 3-1. U.S. Portland cement pl
Page 33 and 34: Table 3-3. (con.) Rank Clinker 3 (1
Page 35 and 36: 5 cement processes: wet process and
Page 37 and 38: Figure 3-3. New technology in dry-p
Page 39 and 40: substantial levels of silica and al
Page 41 and 42: are achieved by clinker coolers of
Page 43 and 44: 126,000 to 963,000 tons/year with a
Page 45: such as crushing and grinding opera
Page 48 and 49: 4.1.1 Thermal NO Formation x Therma
Page 50 and 51: temperatures are on the order of 16
Page 52 and 53: 4-6
Page 54 and 55: expected to produce more fuel NO th
Page 56 and 57: introduce a large proportion of com
Page 58 and 59: will also mean a somewhat lower sec
Page 62 and 63: which indicates an average and the
Page 64 and 65: 4-18
Page 66 and 67: Uncontrolled NO x emissions Plant c
Page 68 and 69: from 2 to 9 lb/ton of clinker, and
Page 70 and 71: Capacity Heat in NO x emissions Met
Page 72 and 73: TABLE 4-3. (con.) Capacity Heat in
Page 78 and 79: in estimating uncontrolled and cont
Page 80 and 81: 13. Letter from Sheridan, S.E., to
Page 82 and 83: 44. Chemecology Corporation Source.
Page 84 and 85: 73. Letter and attachments from Smi
Page 86 and 87: NO control approaches applicable to
Page 88 and 89: 5.1.2.2 Kiln Fuel Changing the prim
Page 90 and 91: oxygen content of the primary air m
Page 92 and 93: tend to recirculate hot combustion
Page 94 and 95: e about 15 to 38 percent depending
Page 96 and 97: combustion system shown in Figure 5
Page 98 and 99: 5-14
Page 100 and 101: Figure 5-3. Schematic of hazardous
Page 102 and 103: 5-18
Page 104 and 105: higher than typical cement kiln flu
Page 106 and 107: window is in the middle of a kiln.
Page 108 and 109: Figure 5-4. Application of the sele
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in Section 5.1.2 is usually difficu
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5.4 REFERENCES 1. Helmuth, R.A., F.
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25. Letter from Wax, J., Institute
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TABLE 6-1. CEMENT KILN MODEL PLANTS
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6-4
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6-6
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The total capital cost is the sum o
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TABLE 6-3. ANNUALIZED COST ELEMENTS
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6-12
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6.1.3.7 Administrative Charges. The
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At this time only three installatio
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6-18
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The annualized costs for low NOx bu
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No additional costs for utilities o
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20 percent PEC cost for contingenci
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TABLE 6-7. ANNUALIZED COSTS FOR RET
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6-28
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PEC for model plant 300,000 ' Heat
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TABLE 6-9. ANNUALIZED COSTS FOR MID
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6-34
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TABLE 6-10. CAPITAL COSTS FOR A URE
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TABLE 6-11. ANNUAL OPERATING COSTS
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6-40
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TABLE 6-12. CAPITAL COSTS FOR AN AM
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TABLE 6-13. ANNUAL OPERATING COSTS
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6-46
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costs range from $9.9 million for t
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The estimated annualized costs for
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6.3 COST EFFECTIVENESS OF NOx CONTR
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emoved. Cost effectiveness were det
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TABLE 6-17. COST EFFECTIVENESS OF R
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6-58
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TABLE 6-18. COST EFFECTIVENESS OF M
Page 176 and 177:
TABLE 6-19. COST EFFECTIVENESS OF U
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6.3.4 Selective Catalytic Reduction
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6-66
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TABLE 6-21. COST EFFECTIVENESS OF S
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6-70
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11. Letter and attachments from Nov
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Tables 7-1 7-2
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TABLE 7-2. REDUCTION IN NO x EMISSI
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model plants described in Section 6
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temperature and excess air may be u
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NOxemissions will form. The heater
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equirement for the flue gas reheati
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