c

E.B. Mull, Jr. and Heinz P. Beutner Interel Corporation, Englewood, Colorado

ABSTRACT

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NTEREL

Dry Additive Process For Control of

Acid Gas and Particulate Emissions

For the majority of incineration processes, air quality control by scrubbing the flue gases prior to fabric filtration is now considered Best Available Control Technology (BACT). This paper discusses Interells Dry Additive Process (DAP) from the points of view of performance, capital, and operating costs. A detailed comparison to the results from the recent EPA study on the IICosts of Flue Gas Cleaning Technologiesii is presented based on the 115 TPD waste-to-energy facility at St. Croix county, Wisconsin.

Paper presented at the ASME Solid Waste Division - Western Chapter Meeting, Salt Lake City, Utah, April 13-14, 1988.

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Introduction

Interel Corporation was founded in 1979 under license agreements with several European manufacturers of air pollution control equipment. Under the partnership with Heinrich Luhr Staubtechnik of Stadthagen, West Germany, Interel supplies fabric filters, heat exchangers and dry acid gas emission control systems. Wet scrubber equipment is furnished under license agreements with Arasin GmbH of Voerde, West Germany and Leisegang Umwelttechnik, Berlin, West Germany.

The Luhr company, since early 1960, has developed specialized technology for applications that are considered difficult for standard dust collection equipment. As a result, the Luhr Fabric Filter has achieved the highest recognition for performance and quality in design. The Dry Additive Process, or DAP, was originally employed for the removdl of HF, HC1 and SO3 from exhaust gas of glass furnaces, ceramic kilns, aluminum salt furnaces and brick kilns. With the promulgation of more stringent regulations, the DAP is now being successfully applied on various waste incinerators. There are currently over two dozen installations of the DAP in the U.S., Canada and Europe.

The Dry Additive Process

Interel’s Dry Additive Process (DAP) for control of acid gas and particulate emissions, is based on a few simple design goals:

* Highest possible performance * Highest reliability in operation * Lowest possible operating cost * Acceptable first capital cost

These Goals can be met in the process flow arrangement as shown in Figure 1.

Application of this process on incinerator emissions first occurred at the Olin Corporation plant in East Alton, Illinois in the summer of 1985. This installation is at present the oldest operating facility utilizing dry scrubbing technology in the U.S. (Figure 2). A more recent installation is at St. Croix County, Wisconsin. Figures 3 and 4 show this facility as it was during the end of construction which occurred in late December, 1987. Since that time, a citizens lawsuit has kept the plant from commercial operation. The suit has since been adjudicated and it is expected that full scale operations will commence by May 1, 1988.

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This facility consists of three (3) Cadoux modular incinerators (115 TPD total capacity) with heat recovery boilers followed by a dual Interel dry scrubbing system. Each dry scrubbing train is sized to accept the flue gases from two incinerators. Due to this design, it is expected that the facility will be able to accept and process MSW on a continuous round-the-clock basis, 365 days per year.

The major design concepts in this system are the utilization of a heat exchanger and subsequent operation at 12OoC (250OF) and a fabric filter with integral reaction tower and high rate dust recirculation.

Operation at 12OoC (250OF) is an optimum condition because:

*

*

*

*

*

It allows for the condensation of volatile components, such as mercury, lead, zinc and cadmium chlorides, chlorinated dioxins and furans and other compounds of incomplete combustion.

The reactivity of hydrated lime with hydrogen chloride and sulfur dioxide is substantially better at lower temperatures than at elevated temperatures.

The heat exchanger is an integral part of the gas-solids reaction system, providing both residence time and surface area as a result of cooling tubes being coated with dry additive reagent. Flue gas flowing over these surfaces intimately contacts the solid reagent, which is continually renewed by additional deposits. The built-in automatic cleaning system periodically removes the reacted material from the heat exchange surface.

The heat exchanger is designed with recirculating cooling air to maintain fixed surface temperatures and prevent any possibility of moisture condensation during cold ambient air conditions. At the same time, thermostatic controls regulate the flue gas outlet temperature to the fabric filter to within +lO°F.

The low flue gas temperature allows the use of more acid and alkaline resistant polyacryl fabric bags in the fabric filter and therefore permits a filter baglife of 3-4 years with near zero failure rate.

INTEREL

* The heat exchanger cools the flue gas without the addition of water, which is used in an evaporative type cooling system. In case of evaporative cooling, the resulting high moisture level in the flue gas frequently leads to processing difficulties in the fabric filter, during start-up, off-line conditions and low flow operation, when low temperature conditions result in moisture condensation on the accumulated dust containing highly hygroscopic calcium chloride.

The advantages of a fabric filter with integral reaction tower and external, adjustable rate dust recirculation are:

*

*

*

*

*

up to 10 times or more dust recirculation can be selected, resulting in additive residence times of up to 3 hrs in the fabric filter system. The long residence time results in maximum possible utilization of the additive.

The high recirculation rates produce a very high dust load, i.e., dust density in the gas phase (similar to a dense phase pneumatic transport system) between the reaction tower and the fabric filter. This high density space extends the residence time from only 0.1 seconds contact in the fabric bags to 1 or 2 seconds intensive contact between gas and solid; this is an essential factor in achieving very low outlet levels of acid gases, e.g., less than 10 PPM at inlet loads up to 1000 PPM (99% removal efficiency).

The high dust recirculation rate maintains a considerable reservoir of dust and therefore provides a buffer capacity for control of sudden spikes in acid gas ,levels as well as any temporary failures of additive supply. Such inlet concentration spikes and/or fee’d failures of up to 15 minutes will not affect the outlet concentration.

The high dust recirculation rate is responsible for the high additive utilization which can be as low as 2:l or less stoichiometric ratio (hydrated lime to hydrochloric acid).

Dust recirculation has another, very important effect: dust agglomeration. The submicron particulates found in incinerator applications when combined with hydrated lime and calcium chloride are effectively agglomerated into coarse particulates, which form a loose permeable dust cake, which requires only low frequency of bag cleaning, thereby extending baglife and allowing conservative air-to-cloth ratios in the range of 3:lto 4:l.

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Most competitive technologies available today for dry additive emission control are primarily based on standard technology for coal fired boiler emissions, amended with lime addition. This involves high temperature operation, use of glass bags and hydrated lime addition without recirculation and with high rates of consumption. This is yesterday's technology, which does not include the benefits of removal of condensibles, or the reservoir benefits of recirculation, and achieves barely acceptable conditions by means of high reagent usage, high bag replacement and high maintenance attention.

costs

The DAP, as has been described herein before, achieves the first two goals i.e.,, highest possible performance concurrent with the highest reliabllity in operation. The question of costs, both capital and operating, are rightfully asked next.

In the summer of last year, the U.S. Environmental Protection Agency (EPA) released the findings from their comprehensive, integrated study of municipal waste combustion. One of the aspects studied was the ttCosts of Flue Gas Cleaning Technologiest1 (EPA/530-SW-87-021E) . The EPA used a model plant approach in the sizing and costing of the emission control systems. Due to differences in the feed waste characteristics, combustion parameters and emissions, separate cost estimates were developed for mass burning (MB) , modular (MOD), refuse-derived fuel (RDF), and fluidized bed, combustion (FBC) type furnaces.

Particulate only, as well as, both acid gas and particulate emissions control systems were estimated.

Interel has essentially employed the same methodology to arrive at both capital and operating costs for the DAP for various sizes of modular incineration facilities. In all cases, a controlled particulate emission level of 0.01 grains/dscf corrected to 12% C02 and 90 to 70 percent reductions of HC1 and S02, respectively, were used. Keep in mind, that the EPA used a spray dryer/fabric filter or wet-dry system as their control device

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Tables 1 through 7 systematically progresses from the characteristics of the flue gas to how much it costs per lb of pollutants removed. Each table is self-explanatory and no

comparison between EPA Table 4-18 (Interel Table 6) and Interel Table 7 is enlightening.

further discussion is warranted, except for Table 6. A

Total annualized costs are:

FACILITY TPD - EPA 100 $ 509,900

Interel $ 390,650

225/250 848,900 711;410 400 1,228,600 1,047,960

% Difference 23.3 16.2 14.7

This confirms our position that for facilities of 500 TPD or less, the dry additive process is more cost-effective than the wet-dry system.

Various factors should be kept in mind when reviewing this data especially when making the comparisons between the EPA and Interel figures. First, Interel's equipment has been sized assuming the incinerators were operating with 100% excess air and not 50% as was assumed in the EPA study. The flue gas volumes for Interel, therefore, are about 30% greater. However, since the control equipment in the EPA study was sized at 125 percent of their design flue gas rate, the equipment for either set of conditions is comparable. Second, no attempt was made to adjust upwards the EPA 1986' dollars to current dollars. Thirdly, Interel 0 f M costs reflect a hydrated lime cost of $85.00/ton compared to the EPA's $55.00/ton and a waste disposal cost of $50.00/ton compared to $15.00/ton. In other words, all of the EPA figures, in our opinion, should be actually higher than what was stated and the resulting differences with Interel should even be greater than we have indicated.

Figures 5 and 6 graphically illustrates these comparisons. Figure 5 reflects capital dollars per ton of daily capacity, while Figure 6 plots facility capacity versus dollars per ton combusted.

These graphs also have plotted data obtained from the recent paper by Dr. Evis Couppis of R.W. Beck (Waste Age Magazine, March, 1988) where he also investigated the cost of dry scrubbing systems for smaller waste-to-energy plants.

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INTE REL I

In conclusion, it has been shown that for plant capacities under 500-600 TPD, the Interel Dry Additive Process is significantly more cost-effective than wet-dry systems for the removal efficiencies now being mandated in BACT criteria. Its many advantages, such as simplicity in design and ease of maintenance, with subsequent lower capital costs, makes it the first choice for todays modern resource recovery facility.

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f This +a”+ coniohs htaotim v p r m t w y to hturl Corporoibn

b *nbh.d cpm th. .JV- cmdltla tho) tha hformtbn con- io*& hwmh will not b. d for ne& sow- p r o c v r v l t or d h c t l y or hdhctly h on woy detrkntol i o th. ht-ut Jht -4 Gorp

NORMALLY CLOSED OPENS ONLY ON UPSET CONDITIONS

( PATENT APPLIED FOR )

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INTEREL CORPORRT ION -Et NTS m’ OKR ” 1-14-(#

PROCESS & INSTRUMENT DlAGRAM INCINERATOR EMISSION CONTROL

8-1111

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FIGURE 1

DRY RDDITIVE FEED SYSTEM

HCINEFlflTOR 1

RECOVERY TPT OILER

HERT EXCHANGER

DRY

TO INDUCED DRAFT FAN MAIN DISCHRRGE STACK

FABRIC FILTER

F i g u r e 2

lnterel Corporation Environmental Control Systems

Refuse I n c i n e r a t o r , 24 t o n s l d a y 2 x 13,500 ACFM a t 450°F

F a b r i c F i l t e r 2 x Type MWF 2.513.512.0 F a b r i c Area 2 x 3 , 6 6 0 ft?

Hydra ted Lime A d d i t i o n For Acid Gas C o n t r o l

O l i n Corp . , East A l t o n , I L

(A/C = 3 .7 )

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lnterel --- FIGURE 3 Corporation

Environmental Control Systems

115 TPD Modular MSW Incineration System Dry Additive Process, Type KUV (Dust Recirculation)

American Resource Recovery/Cadoux, 1nc.-St. Croix County, New Richmond,WI

Gas Flowrate: 30,200 ACFM at 480°F Heat Exchanger: Type 2xFU 2.5/3.0/2.0 (5167 ft2 Fabric Filter: Type 2xDWF 2.5/3.0/2.0 (9688 ft ) a

-in-

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lnterel FIGURE 4 Corporation --

Environmental Control Systems

115 TPD Modular MSW Incineration System Dry Additive Process, Type KUV (Dust Recirculation)

American Resource Recovery/Cadoux, 1nc.-St. Croix County, New Ric,,mond,

Gas Flowrate: Heat Exchanger: Fabric Filter: Type 2xDWF 2.5/3.0/2.0 (9688 ft )

30,200 ACFM at 480°F

Type 2xFU 2.5/3.0/2.0 (5167 ft2 a JI

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TABLE 1

Feed Waste Composition Calculated Flue Gas Composition

Constituent

Carbon

Hydrogen

Oxygen

Nitrogen

Sulfur

Chlorine

Inerts

Water

Weisht .?

26.73

3 .6

19.74

0.17

0.12

0 .32

22.18

27.14

Constituent VOl % D m Vol % Wet

co2 9.34 8 .00

02 10.63 9.12

N2 79.98 68 . 57

so2 0 . 0 1 0 . 0 1

HC1 0.04 0.03

H 2 0 NA 14.27

Mole Wt. 29.93 28.23

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TABLE 2

Model Plant Controlled and Uncontrolled Emission Data

Total facility daily charge rate, TPD

No. of combustor units

Hourly charge rate per combustor at 100% utilization, lbs/hr

Excess combustion air, % of theoretical

Uncontrolled emission factors particulate gr/dscf @12% C02 lb/hr (per combustor) tons/year (entire

50 100

2 2

2083 4168

225

3

6250

400

4

8333

600

3

16,667

< 100 >

< 0.11 > 1.96 3.92 5.89 7.85 15.70

plantj * 15.7 31.4 70.7 125.6 188.4

Hydrogen chloride PPm dry < 400 lb/hr (per combustor) 7.1 14.2 21.3 28.4 56.8 tons/year (entire plant) * 56.8 113.6 255.6 454.4 681.6

Sulfur dioxide PPm dry < 160 >

tons/year (entire lb/hr (per combustor) 5.0 10.0 15.0 20.0 40.0

plant) * 40.0 80.0 180.0 320.0 480.0

3

' 1 .

Flue gas composition per combustor, at dry scrubber outlet Temperature , OF 4 250 *

Volumetric flow rate SCFM ACFM

3640 7283 4876 9756

1 0 , 9 2 3 1 4 , 5 6 4 2 9 , 1 2 9 1 4 , 6 3 3 1 9 , 5 1 0 39 ,022

Particulates gr/dscf @ 12% C02 < 0 . 0 1 0 > lb/hr (per combustor) 0 . 1 8 0 . 3 6 0:54 0 . 7 1 1 . 4 2 tons/year (entire plant) * 1 . 4 2 . 9 6 . 5 1 1 . 4 1 7 . 0

Hydrogen chloride removal efficiency, % < 9 0 > lbs/hr (per 0 . 7 1 1 . 4 2 2 . 1 3 2 . 8 4 5 . 6 8

(entire plant) * 5 . 7 1 1 . 4 2 5 . 6 4 5 . 4 6 8 . 2 combust or) t ons/year

Sulfur dioxide removal efficiency, % < 7 0 >

combustor) tons/year (entire plant) * 1 2 . 0 2 4 . 0

lbs/hr (per 1 . 5 3 . 0 ' 4 . 5 6 . 0 1 2 . 0

5 4 . 0 9 6 . 0 1 4 4 . 0

* Entire plant calculations based on 8000 hours of operation annually.

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TABLE 3

Drv Lime Material Balance

Waste Throuqhwt Rate. TPD

Lime equivalency ratio, % Lime purity, % Lime consumption,

lbs/hr TPY

Amount of solids for disposal, lbs/hr (TPY)

Flyash

Unreacted lime and impurities

Reaction products

Total solids

50

155 95

40 160

3.6

100

155 95

80 320

7.1 (14.4) (28.4)

19.2 38.4 (76.8) (153:6)

40.6 81.2 (162.4) (324.8)

63.4 126.7 (254) (507)

225

155 95

180 720

16.0 (64.0)

86.3 (345.2)

182 . 7 (730.8)

285.0 (1,140)

400

155 95

320 1,280

28.6 (114.4)

153.4 (613 . 6) 324 . 9

(1,299.6)

600

155 95

480 1,920

42.8 (171.2)

230.2 (920.8)

487.3 1,949.2)

760.3 (3,041)

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TABLE 4

Annualized Operatha Cost Basis

Direct Costs

Operating labor Labor hours

Supervision

cost

Utilities Electricity

Water

Sewage

Chemicals (Hydrated lime)

Annual maintenance

Waste disposal

Indirect Costs

Overhead

Taxes, insurance and administrative overhead

Capital recovery

1 Man hr/shift for 50 f 100 TPD

2

15

facilities Man hr/shift for all other facilites

% of total operating labor

$ 12.02/hr for operating labor $ 14.42/hr for supervision

$ 0.064/KWH

0

0

10% additional cost over pebble $85.OO/ton

lime;

2% of total capital cost

$ 50.00/ton of waste delivered to land fill (@lo% moisture)

60% of operating and maintenance labor

4% of total capital cost

15 years life; and 10% interest rate on money

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TABLE 5

CarJital Cost Estimates

Jnterel DAP Installations

50 TPD

100 TPD

225 TPD

400 TPD

600 TPD

$ 1,170,000

$ 1,380,000

$ 2,300,000

$ 3,240,000

$ 4,980,000

Notes:

1. All 1988 dollars based on 8000 hrs/yr operation. 2. Installation costs at 30% of the equipment cost. 3. Scope includes multiple Interel DAP equipment trains plus

ancillaryequipmentincludinginduceddraftfansinterconnecting ductwork,10O1 maindischargestack (FRPlined), andacontinuous emissions monitoring system. All capital cost estimates include a 20% contingency factor.

4.

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TABLE 6

EPA Annualized Cost Figures For Wet-Dry Scrubber Installations

TMLE 4-18. ESTICIATEI, NVMMIZEO Of'ERATING COSTS OR SD F f YSTEMS FOR MODEL NEW HOOULAR W S T O R lACILIflESi

(Aupst 1986 dollars based on 8,000 hrr/yr operatloh)

LL"t Operrtlng labor

S u p rv I s Ion ut11 It Ies:

Eloctr I c l t y Water

Chalcal r (11m) Ma lntenanceC

Waste dlsposal

T p W dlrect

Y Overhead (6(11; of I 28,700 I 28,700 1 290100 o ra t ln labor and m6ntenaLe labor)

Model - f Q u 0.03

24,000

4,300

39,600 800

170600 39,200 7.600

w 0.02

24,000

4,300

39,600 800

17~600 39,200

7.700

IO $d) !ddL J&QL

24,000

4,300

390600 800

170600 400400 7 D 700

Model m 0,03

240000

40300

810400

20000 440200 630500

18,900

2Pu 0.02

24,000 4,300

87;400

2,000 440200 630500

19,100

hP;{

-QbQl-

24,000 4.300

87,400 20000

44.200 65 0 900

19,200

1350200 20 900

70,600 83,600 300400

210000 4,300

135 D 200 2.900

700600 830600 30,600

24 D 000

4,300

135,200 2,900

700600

95,600 300800

aFor 90 and 70 percent control of HCI and SO2, respectively.

CAssmes SO percent of ulntenanca cost for labor.

unttr of gr/drcf a t 12 percent C02.

360000 360000 360800

127o000 1270000 131,800

45,700

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TABLE 7

Estimated Annualized Operatins Costs

Interel DAP Installations

Throuahwt Rate.TPD 50

Direct Cost Operating labor 12,020

Supervision 2160

Utilities Electricity 24,120

Water 0

Sewage 0

Chemicals (lime) 13,600

Maintenance (1) 23,400

100

12,020

2160

40,090

0

0

27,.200

27,600

225

24,04Q

4320

87,300

0

0

61,200

46,000

400

24,040

4320

141,320

0

0

108,800

64,800

600

24,040

4320

211,920

0

0

163,200

99,600

Waste Disposal 14,090 28,160 63,340 112,650 168,960 Total Direct: 89,390 137,230 286,200 455,930 672,040

Overhead 15,530 16,790 30,820 36,460 46,900

Taxes, insurance and administration 46,800 55,200 92,000 129,600 199,200

Capital recovery 153,830 181,430 302,390 425,970 654,730 Total Indirect: 216,160 253,420 425,210 592,030 900,830

Total Annualized cost $305,550 390,650 711,410 1,047,960 1,572,870

(1) Assumes 50 percent of maintenance cost for labor

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TABLE 8

Cost Effectiveness

Facility Acid Gas Capacity Removed TPD TPY

Interel

50

100

225

250

400

600

79 --- 157 158

356 --- --- 392

627 633

949 ---

$/lb of Acid qas removed

Interel

1.93

1.24

1.00

--- 0.83

0.83

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24000-

22000-

20000-

18000-

16000 - 14000-

12000-

10000-

8000-

6000-

4000-

2000-

FIGURE S

i

CRPITRL COST

t

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LEGEND INTEREL C - - - - 4) R.W. BECK 4 9 B) EPA STUDY (------------E) ADJUSTED EPA ( EA)

L --E

I I I I I I I I I I I I

50 100 150 200 250 300 350 $00 450 500 550 600

FRC IL ITY CAPAC ITY, TPD

INTEREL

n W I- cn 3

E 0 0

m

0 =I I-I U W rL

201 1R t

FIGURE 6

TOTAL ANNUALIZED COSTS

;.$ 14

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LEGEND INTEREL (- - - - - 4) R.W. BECK (* *, B) EPA STUDY (-----------.E) ADJUSTED EPA ( EA)

I \ -*- . -

301

"1 *I

50 100 150 200 250 300 350 400 450 500 550 600

F A C IL ITY CAPACITY, TPD