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

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The concept of external flue gas recirculation for NO x reduction has not been demonstrated in cement kilns. Similarly, the potential of secondary combustion of fuel in conventional kilns (by "mid-kiln" firing) as an NO control technique has been x evaluated for whole tire burning only. This technique can be potentially applied with other waste-derived fuels as well and needs further demonstration. Secondary combustion of fuel is inherently present in all precalciner kilns and preheater kilns with riser duct firing and such kilns produce less NO emissions x compared to long dry kilns. Selective catalytic reduction (SCR) uses ammonia in the presence of a catalyst to selectively reduce NO emissions. x There have been limited pilot test programs of SCR. Selective noncatalytic reduction (SNCR) technology appears to be applicable to preheater/precalciner type kilns with limited data indicating its effectiveness. SNCR reduces NO with ammonia or urea without x a catalyst. SNCR is not considered applicable to long wet and dry kilns due to difficulties involved in continuous injection of reducing agents. There have been a few demonstrations of SNCR at preheater/precalciner kilns. Molar reagent ratio, temperature, and gas residence time in the appropriate temperature window are primary factors affecting NO x reduction efficiency. Table 2-2 presents the potential NO x reductions with these techniques. 2-4
TABLE 2-2. ACHIEVABLE NO REDUCTIONS WITH VARIOUS NO x x CONTROL TECHNOLOGIES ACHIEVABLE NO x EMISSIONS NO x CONTROL TECHNOLOGY REDUCTION (%) Process Modifications 25 Stayed combustion in 30 - 45 precalciner Conversion to indirect firing with a low NO burner 20 - 30 x Mid-Kiln firing of tires in long kilns 20 - 40 SNCR 30 - 70 SCR 80 - 90 2.3 COSTS AND COST EFFECTIVENESS OF NO CONTROL TECHNOLOGIES x Capital and annualized operating costs as well as cost effectiveness were determined for technologies for which detailed costs could be developed: Low NO burner, mid-kiln firing x conversion, SNCR and SCR. Since there are limited installations of these technologies, the capital and annualized costs were based on the information provided by vendors and guidelines provided by the U.S. Environmental Protection Agency/Office of Air Quality Planning and Standards (EPA/OAQPS) Control Cost Manual. Tables 2-3 and 2-4 present the total capital and annualized operating costs for each of the three control technologies as applied to model plants defined in Table 6-1. The low NO burner x capital costs range from $1,270,000 to $2,180,000, whereas the annual costs range from $267,000 to $423,000. Capital costs for mid-kiln firing conversion range from $391,000 to $707,000. Annual costs range from $128,000 to $207,000. The urea-based SNCR capital costs range from $671,000 to $1,240,000 for preheater/precalciner kilns. The urea-based SNCR annual costs range from $438,000 to $820,000. The ammonia-based SNCR 2-5
Page 1 and 2: 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
Page 7 and 8: 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: 2.2 NO EMISSION CONTROL TECHNOLOGIE
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 60 and 61: ILC systems: In these systems, the
Page 62 and 63: which indicates an average and the
Page 64 and 65: 4-18
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Uncontrolled NO x emissions Plant c
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from 2 to 9 lb/ton of clinker, and
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Capacity Heat in NO x emissions Met
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TABLE 4-3. (con.) Capacity Heat in
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in estimating uncontrolled and cont
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13. Letter from Sheridan, S.E., to
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44. Chemecology Corporation Source.
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73. Letter and attachments from Smi
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NO control approaches applicable to
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5.1.2.2 Kiln Fuel Changing the prim
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oxygen content of the primary air m
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tend to recirculate hot combustion
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e about 15 to 38 percent depending
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combustion system shown in Figure 5
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5-14
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Figure 5-3. Schematic of hazardous
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5-18
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higher than typical cement kiln flu
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window is in the middle of a kiln.
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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
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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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NOx Emissions from Cement Mfg - US Environmental Protection ...

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