Total Annualized Cost for BACT

In Chapter 6, top‐down BACT analyses for criteria pollutants were presented for a gas turbine facility (Section 6.6). As an example, here we present the TACs and costs per ton pollutant of particulate matter removed against exhaust gas rate and boiler steam capacity for four control options: (i) multi‐cyclones (MC), (ii) Venturi scrubber (VS), (iii) electrostatic precipitator (ESP), and (iv) fabric filter (FF). The TACs were computed using the EPA’s air pollution control cost manual and the control‐cost spreadsheets (APTI 1995; USEPA 1996). The USEPA control‐cost spreadsheets consider most aspects of cost evaluation, using operating parameters, design parameters, capital costs, and annual cost. The TAC spreadsheets for control options, e.g. MC, FF, ESP, and VS, are given in the report by Das (2003).

The TAC for a chosen boiler exhaust flow rate at 18 685 dscfm (Table 7.10). Cost effectiveness, or dollar per ton of pollutant removal, is one of the key economic criterion used to determine if a control option is acceptable for permitting use. Cost effectiveness is calculated as the TAC of the control option being considered divided by the baseline emissions minus the control option emissions rate (Figures 7.7 and 7.8) (Das 2001, 2003; Peters et al. 2002).

Cost Per Ton (T) of Pollutant Removal

The following is the calculation of ton per year (T/Y) and dollar per ton ($/T) using Figure 7.7 for four control technologies (MS, VS, ESP, and) for particulate matter (PM) removal.

EXAMPLE 7.6 MULTI‐CYCLONE

Basis: 1 minute

(where dscfm = dry standard cubic feet per minute)

(where 7000 grains (gr) = 1 lb)

(where 1 T = 2000 lb)

For 90% removal efficiency

For an inlet exhaust gas flow rate = 18 685 dscfm

TAC for MC at 18 685 dscfm

Table 7.10 TAC and cost per ton of PM removals VS flow rate and boiler steam capacity.

Source: From Das (2003).

Flow rate (dscfm)	Steam (lb/h)	Cost, MC	Cost, VS	Cost, ESP	Cost, FF	T/Y,MC 90%	$/TY, MC	T/Y,VS 90%	$/TY, VS	T/Y,ESP 99.5%	$/TY,ESP	T/Y,FF 99.5%	$/TY, FF
1 500	3 500	18 203	124 592	66 563	107 370	101	180	101	1 229	112	594	112	958
6 744	15 000	37 960	139 485	147 139	140 647	456	83	456	306	504	292	504	279
18 685	40 000	82 292	173 398	296 329	216 415	1 263	65	1 263	137	1 396	212	1 396	155
21 118	45 000	91 283	179 983	320 471	231 852	1 428	64	1 428	126	1 578	203	1 578	147
67 540	137 776	264 428	298 057	711 959	595 016	4 566	58	4 566	65	5 045	141	5 045	118
99 478	200 000	381 768	376 049	967 426	797 667	6 725	57	6 725	56	7 431	130	7 431	107
14 1109	280 000	534 321	475 904	1 316 887	1 061 828	9 539	56	9 539	50	10 541	125	10 541	101
223 023	435 000	833 661	668 958	1 996 247	1 581 600	15 076	55	15 076	44	16 660	120	16 660	95
268 464	520 000	999 392	774 805	2 355 281	1 869 935	18 148	55	18 148	43	20 054	117	20 054	93
311 500	600 000	115 6191	874 473	2 690 738	2 143 013	21 057	55	21 057	42	23 269	116	23 269	92
365 608	700 000	135 3146	999 146	3 107 276	2 486 341	24 715	55	24 715	40	27 311	114	27 311	91

Assuming grain loading in the boiler exhaust gas stream = 2.0 gr/dscfm.

Multi‐cyclone (MC) efficiency = 90%.

Venturi scrubber (VS) efficiency = 90%.

Electrostatic precipitator (ESP) efficiency = 99.5%.

Fabric filter (FF) efficiency = 99.5%.

EXAMPLE 7.7 VENTURI SCRUBBER

Input PM loading to VS per minute = 2.0 gr/dscfm

For 18 685 dscfm

For 90% removal efficiency

Annualized cost at 18 685 dscfm = $173 398 (Figure 7.7)

EXAMPLE 7.8 ELECTROSTATIC PRECIPITATOR

Input PM loading to ESP and FF per minute = 2.0 gr/dscfm

For 18 685 dscfm

For 99.5% removal efficiency for both ESP and FF

Annualized cost at 18 685 dscfm = $296 329 (Figure 7.7)

EXAMPLE 7.9 FABRIC FILTER

Input PM loading to FF per minute = 2.0 gr/dscfm

For 18 685 dscfm

For 99.5% removal efficiency for FF

Annualized cost at 18 685 dscfm = $216 415 (Table 7.10)

Conclusion: For the boiler exhaust flow rate at 18 685 dscfm, MC could operate at least expensive rate ($65/T) having 90% efficiency to remove PM₁₀; on the other hand, ESP could operate at most expensive rate ($212/T) having 99.5% efficiency to remove PM₁₀.