TDF as Fuel in Waste Wood Boilers at Pulp and Paper Mills

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Pulp mills generate large amounts of waste wood products, such as bark and contaminated wood residues, in the process of making wood chips for the pulp digester. Also, many paper companies operate saw mills adjacent to the wood yard to maximize resources; these mills generate waste wood slabs, logs, trimmings, pellets, shavings, saw dust, etc., that can be a solid waste disposal problem.1 Heating value of these waste wood ranges from about 7,925 to 9,010 Btu's per pound of fuel, on a dry basis. Tires, as mentioned earlier, generate 15,000 Btu's per pound. Bark is the most common component of waste wood in the pulp and paper industry.1

Many mills burn this wood waste in boilers to obtain heat energy for process steam, and to alleviate possible solid waste disposal problems. These waste wood boilers are known as "hog-fuel" boilers. A base load of supplemental fuel of some kind is required in hog-fuel boilers, because the significant variations of the size, moisture content, and heating value of the wood waste may not allow consistent boiler performance. Supplemental fuel facilitates uniform boiler combustion, and ensures that a minimum amount of power is generated regardless of the fuel value of the wood waste at any one time.

Operators traditionally use coal, gas, or oil, whichever is the cheapest fuel in their area, as the supplemental fuel. For the past 15 years, however, some paper mills have used TDF commercially or on a test basis in hog-fuel boilers.2 The consistent Btu value and low moisture content of TDF in combination with its low cost in comparison to other supplemental fuels make TDF an especially attractive alternative fuel in this industry.

The economic value added by the use of TDF varies by location, and, thus, TDF is not universally the most economical fuel for use in pulp and paper mill hog fuel boilers.

5.1 INDUSTRY DESCRIPTION

As of the Summer of 1991, at least 10 pulp and paper companies are adding tire-derived-fuel (TDF) to their hog fuel boilers as an alternative supplemental fuel. In addition to boilers at pulp and paper plants, one boiler at a silicon manufacturing facility burns TDF supplementally with their primary fuel of waste wood chips. Information and emissions data from this boiler have been included with this section. Table 5-1 contains a list of pulp and paper mills that have burned TDF commercially, or have tested TDF in the past.

The most common type of boiler configuration to bum hog-fuel is the spreader stoker type, although some overfeed stokers also exist. Spreader stoker boilers can burn fuel with high moisture content, are relatively easy to operate, and have relatively high thermal efficiency. Overfeed stoked boilers have lower particulate emissions relative to spreader stoker boilers because less combustion occurs in suspension.13

In recent years, environmental concerns over water quality have led to installation of waste water treatment plants at pulp and paper mills. The underflow from the primary clarifier has generated another solid waste disposal problem. To solve this problem, some mills are feeding clarifier sludge to hog fuel boilers. The high moisture content of the sludge in conjunction with its low Btu content creates more difficult operating conditions for the furnace. Comparative composition of TDF, coal, wood waste,

Company and location

Air Emissions Int Cats loll«r(s) Deacrlptlon

Coenente/Isferonces

Auguat« Newsprint August«, CA

Chaaplon International luckaport, HE

ChMplon International Seriell, NN

Crom 2al Urbach Port Anéeles, UA

Dow Corning Corporation Midland, MI

Fort Howard Corporation IIneon, CA

Fort Howard Corporation Gr*cn lay, Ul

Georgia-PeclfIc Paper Cedar Springt, CA

Georgla-Paclf Ic Tot ado, Ott

Currant

Shredded; 2" or U>a, ulr« free; 2.5 tona/hr (peraltted 143 to 3.S tona/hr)

Past

Current TDF or oil used with wood;

Current

Current

Current 3X;

2"*2" and 1"xt"; 30 tons tire/1000 tons coal p«r day

Paat

Unknot«! Unknown ret; MO,. Betels, non-nethane orgánica; teats wer« don« with coal «t 80X I«vaI both for baseline and TOF test, IDF at 1.5X, and rest wood chip«.

No; Non« required

Yea; Test regularly for particulate; also h«v« tested for NO, and K^

4 boilers; 3 burn oil only, 4th Safarenca 3

burns aultlfuela at 500,000

Iba/hr.

leference 3

Oil boiler converted to bum hog fuel; venturl scnifcer

275,000 Ib/hr, ESP

Plant has 6 bollers totalt 3 inderfeed typ« that uaa 2"x2" TDF; 2 spreader-stoker typ« that use 1"«1" TDF; 1 cyclone fed with no IDF use now, but us« planned.

(oiler Is spreader/stoker travelIng grate type; generates S00,000 lb* stean/hr tt B80 pa Ig and 900*F. TDF Is fed on the bark conveyor.

Plant had aieny violations, even k*>en not burning tires. Given 141 on tire burning currently lafarenca 3

Silicon production facility; TDF uaed In wood chip boiler, laference 3

Product recycled papar; coal oth«r bast load fu*l. laferences 3 and 4

Used to b« Great Southern Paper; have turned TDF for «everal years; peraltted for 100 tpd TDF, but averag« 60 tpd; coal other bas« load fuel. References ^ arid 6

laference 6

to to vo

Coapany end location

IDF Um

Air EbIiiIotk Te«t Data loller(») Datcrlptlon tt/Raforonce«

o"

Inland-iona Paper im, CA

Packaging Corp. of

Acerl"

Port Tomaend Paper Fort Tom*end, UA

(cm Kraft Pulp and Paper Kill Roae, CA

tourfit Newaprint Nn£urg, 0«

Sonoco Producta Co. Harttvllle, SC

Willanette Induatrlat Albany, 0«

Current

10 1 TDf In 2 of 4 boitera

Current

Current; usually 3-eX of fuel I* oll or TDF

Current IX

2"x2"

Current 2X

2-xt" TDF

Tea; opacity, particulate, and MO,.

Y««; teat« performed for criteria, haiardoua, end toxic pollutant«. Including retail and dloxln/furan; teitlng dona on an overall facility ba«l«, with all boiler« vented together, «oo« not burning tire«.

Unknown

Tat; boiler f 10, particulate, VOC

Plant h«> * boiler« tot«li 2 burn coal only; 2 burn hog fuel and about 10X (Itu basla) TDF. loth hog fuel boiler« are Coabuatlon Engineering boiler« rated at 165,000 lb* «ttaa/hr with vibrating atoker grate«. Mi ft In «lie. All 4 boiler* are vented together and controlled by •ulticyclonet and one ESP. TDF fed from a hopper with a variable •peed screw outflow, and ere added to the bark atreaa.

Three traveling grate •preader/ttoker type boiler*; all vent to coonon duct, then *ep*r*te to two ESP1« and «tack«.

Two boiler« ualng TDF; #9 «preadtr/ttoker, US,000 Ib/hr, filed grate«, venturl acni&er; I 10 «preeder/ttoker, 100,000 Ib/hr traveling grate, venturl acrubber ]u«t replaced with ESP 4/91

Control by wet tcrti&er; «toker fed type hog fuel boiler. Feed 1« done with a hoaenede hopper and feed conveyor. TDF It wined with the hog fuel after the hog fuel exit« * dryer.

Neve been burning TDF for 3 yean; did obtain parait and)fleet ion. Reference« 2, 3, and 7

Formerly Owene llllnolt, Nekoo««, and Georgia Pacific; produce« corrugated paper aaterleli. »iterance 6

Inference 3

Reference 3

Nope to Increaae percent TDF llalt after ESP operational. Reference« 3 and 9

Reference 3

and clarifier sludge were provided in the introduction in Table 1-2 and is reprinted here.

Table 1-2. Comparative Fuel Analysis, by Weight3

Fuel

Cayonsnt (percent)

Heating Value

Carbon

Hydrogen

Oxygen

Nitrogen

Sulfur

Ash

Moisture

Btu/lb

TDF

83.87

7.09

2.17

0.24

1.23

4.78

0.62

15,500

Clarifier Sludge

4.86

0.49

2.17

0.47

0.26

3.16

88.69

924

Coal

73.92

4.85

6.41

1.76

1.59

6.23

5.24

13,346

Wood Uaete

Test 1

30.98

3.16

23.33

0.13

0.04

1.31

41.05

5,225

Test 2

28.29

2.37

20.95

0.13

0.03

1.49

46.73

4,676

Test 3

2S.67

2.54

19.17

0.12

0.03

1.11

51.36

4,031

Test 4

24.71

2.44

18.46

0.12

0.02

1.13

53.12

4,233

5.2 PROCESS DESCRIPTION

Most waste heat boilers are fairly small, ranging from 100,000 to 200,000 pound of steam per hour (100 to 200 MMBtu's per hour). Overall feed rate of hog fuel averages about 84 tons per hour. The maximum rate of. TDF is between 10 and 15 percent of the total Btu's required. The reason for this is that one of the main uses of the hog fuel boiler is to burn hog fuel. Ten to 15 percent TDF is all that is needed to accomplish this.

Varied boiler firing configurations are found in hog fuel boiler applications, including dutch oven, fuel cell, spreader stoker with traveling or vibrating grates, and cyclone stoker types. As stated previously, the spreader stoker is the most widely used of these configurations. Spreader/stoker boilers in the pulp and paper industry often have an air swept spout added to the front of the boiler to feed bark down on top of the coal.14 Wood is puffed at one-

second intervals through the spout so it falls onto the coal base on the grate. The air swept spout can also blow TDF sized up to about 3" x 2", without any additional capital equipment expenditure. However, to retrofit an existing spreader/stoker boiler with an air swept spout to accommodate TDF fuel is not economically feasible.14

Alternatively, in the waste heat boiler, bark, wood waste, and sludge are conveyed to an overhead, live-bottom bin. This fuel is then introduced to the boiler furnace by an air jet, which casts the fuel out over the stoker grate in a thin, even layer.1 The advantage of this type of boiler configuration is that it has a fast response to load changes, has improved combustion control, and can be operated with a variety of fuels.1

If coal is the primary base load fuel, it is typically pulverized and fed to separate pneumatic systems that feed individual burners. TDF, when used, is usually fed via a variable-rate weigh belt or variable-speed screw conveyor to the bark conveyor feeding the overhead bin. This configuration permits effective mixing of TDF, bark, wood waste, and sludge.

Figure 5-1 is a schematic diagram of the process flow through Smurfit Newsprint's two hog-fuel boilers. Wood sludge, waste wood chips, and bark are fed into the two boilers. TDF is added as a supplemental fuel, and is currently limited by an air permit to 1 percent of the boiler fuel. Exhaust from the combustion chamber of the boilers exits through multicyclone systems and scrubbers, which collect ash from the exhaust streams.15

Diagram Bark Conveyor

Figure 5-1. Smurfit Newsprint Process Flows15

5.3 EMISSIONS, CONTROL TECHNIQUES AND THEIR EFFECTIVENESS 5.3.1 Emissions

This report examined six sets of test data from waste wood boilers at pulp and paper mills (and one at a silicon manufacturing plant). Of the six, control at one is unknown, two are controlled by venturi scrubber, two by ESP's, and one by both a scrubber and an ESP. The State of Washington tested two of these facilities: Port Townsend Paper and Crown Zellerbach Corporation. Table 5-2 presents the particulate, heavy metals, and polynuclear hydrocarbons (PNA) emissions data from these test. Both of these plants use venturi scrubbers for emissions control. Smurfit Newsprint has performed several tests over the last 3 years. Particulate results at Smurfit are summarized in Table 5-3. Results of testing on other criteria pollutants and heavy metals are contained in Table 5-4. Packaging Corporation of America (formerly Nekoosa Packaging) tested criteria pollutants, metals, PCB's, and dioxins and furans at baseline and about 1.5 percent TDF. These results are summarized in Table 5-5. Champion International in Sartell, Minnesota, tested particulate, SOx, metals, and semi-volatile organics, although the results of the organics testing while burning TDF were lost in a laboratory accident. Results of this test are found in Table 5-6. Dow Corning, a silicon manufacturing facility, burns TDF in their wood chip boiler, and has performed air emissions testing for particulates, S02, NOx, and metals. These data are summarized in Table 5-7. The following paragraphs summarize the test results by pollutant for each plant. Figures are provided that graph the emissions change as TDF percent increased.

Fuel use varied significantly during the six tests evaluated here. Three burned 100 percent wood waste for baseline, and

Table 5-2. Emission of PNA's and Metals from Port Townsend Paper and Crown Zellerbach Corporation16,17,24 (Venturi Scrubber Controlled)

Port Tounaand Paper (2/25/64)

Crow Zilltrbtdi Corp.

(6/10/86)

Pollutant

Weit« Wood

♦ 5X Oil

Weit* Wood ♦ 7X T0F

Waft* Wood

♦ 12* Oil

Weite Wood ♦

2X TDF ♦ 11X Oil

KKBtU

Ib/hr

Ibx104/ HHfitu

Ib/hr

ibxIO"4/ HHfitu

Ib/hr

lb*104/ HHBtu

Pmlfyli!»

46.2

63.8

11.0

15.4

Hct«U

Araanlc

NA

NA

3.3

6.28

(arlua

257.4

350.5

11.3

29.1

Cadilua

0.009

42.8

0.007

31.3

2.9

5.8

Oiroatlua

0.01

St.9

0.01

34.9

0.5

3.5

Ccppar

2,415.4

2,296.8

30.7

40.0

Iron

1,999.8

2,574.0

263.1

377.8

Laad

0.1

603.9

0.03

132.3

64.0

72.4

Nlckat

0.1

689.0

0.01

59.0

3.5

3.6

Vanadliaa

0.2

902.9

0.001

8.9

3.0

7.5

Zinc

3.1

U, 790.6

48.8

249,480.0

0.S

2,455.0

3.1

16,381.4

fHA't

Anthracan*

0.03

9.9

0.01

26.7

1.0

0.6

Phananthrcne

0.1

«19.8

0.2

772.2

45.3

16.7

Fluor»nthana

<59 .4

235.6

37.4

14.2

Pyr*na

249.5

380.2

47.8

21.7

lenzo(b)Fluoranthena

0.6

1.2

2.3

0.0

l*nio(k)fluoranthant

0.6

0.6

0.7

0.0

tanio(a)fluoranthena

1.6

2.2

0.0

0.0

Chryaen*

3.2

2.4

0.0

0.0

TOTAL PHA'a

0.3

0.02

Table 5-3. Summary of Particulate Tests on Two Hoo-fuel Boilers at Smurfit Newsprint, Newberg, OR18'19'20'25

#9 Boiler - Particulate*

Table 5-3. Summary of Particulate Tests on Two Hoo-fuel Boilers at Smurfit Newsprint, Newberg, OR18'19'20'25

Date

TDF, %

FM Emissions, lb/hr

3/13/87

0.0

315*

1/29/87

1.0

73

3/6/87

1.5

162.0

2/9/87

1.8

>140.6

• Controlled by venturi scrubber

#10 Boiler

- Particulate*

Date

% TDF

PM Emissions

lb/hr tons/yr*

5/28/87

0

26.8 117

5/28/87

1

45.6 200

5/28/87

1.5

57.2 251

11/14/87

1

30.5 134

8/14/90

1

26.0 114

" Controlled by venturi scrubber b Assumes 8,760 h/yr

Table 5-4. Summary of Non-particulate Testing on the #10 Boiler at Smurfit Newsprint, Newberg, OR '19,20,25

#10 Boiler - Other Pollutants"

Pollutant_Date_% TDF lb/hr ton/yr

Criteria

VOCb

5/28/87

0

25.1

110

5/28/87

1

8.0

35.

1

5/28/87

1.5

69.9

306

11/14/89

1.0

1.2

5.

3

8/14/90

1.0

1.0

4.

4

NOxe

11/14/89

1.0%

82.8

36.

3

8/14/90

1.0%

33.4

146

so2d

11/14/89

1.0%

4.8

21

8/14/90

1.0%

ND

ND

CO*

11/14/89

1.0%

94.9

417

8/14/90

1.0%

146

639

Barium

11/14/89

1.0%

0.000

-

Cadmium

11/14/89

1.0%

0.017

-

Chromium

11/14/89

1.0%

0.006

-

Copper

11/14/89

1.0%

0.020

-

Iron

11/14/89

1.0%

0.260

-

Lead

11/14/89

1.0%

0.037

-

Zinc

11/14/89

1.0%

3.82

-

Titanium

11/14/89

1.0%

0.000

" Controlled by venturi scrubber b VOC limit is 189 TPY c NOx limit is 2,850 TPY d S02 limit is 250 TPY * CO limit is 570 TPY

Table 5-5. Summary of Tests on 3 Hog-fuel Boilers at Package Corp. of America (formerly Nekoosa)21 November 7, 1989

Pollutant

% Change

Particulate

Chromium VI Metals Arsenic Cadmium Lead Nickel Zinc Mercury Chloride Benzene

19.0 114.36 111.09 180.67 0.0129

0.019 <0.008 0.715 0.0005 0.96 <5.57xl0"2

20.7 107.06 147.23 268.00 0.036

0.003 <.0023 0.018 <0.008 0.851 0.0006 1.82 6.65X10*2

NOTE: All three boilers are ducted to common duct and then to two ESP's.

' Below detection limit (DL).

Table 5-6. Emissions Burning TDP and Waste Wood Dow Corning Corporation, Midland, MI22«* March 9-29, 1989

Pollutant

OX

IDF

SX IDF

10X T0F

15X IDF

Ib/hr

lb/MHBtu

Ib/hr

lb/MHBtu

X Change

Ib/hr

Ib/HHBtU

X Change

Ib/hr

lb/MHBtu

X Change

Particulate

4.29

0.0122

7.53

0.0205

«68

11.22

0.0305*

♦150

38.10

0.1130k

♦826

Ceäiiua

0.00049

1.39*10"*

-

-

N/T

-

N/T

0.0028

8.21x10"*

♦491

Total Chronica

0.00128

3.64x10"*

-

-

N/T

N/T

0.0019

5.57x10"*

♦53

Zinc

0.0634

1.8* 10"*

-

-

N/T

-

N/T

11.32

0.03

♦16,567

Berylllua'

NO

NO

-

-

N/T

-

N/T

NO

NO

NO

NO.'

-

0.153

-

0.162

♦6

0.133

-13

-

0.081

-47

»I*

-

0.026

-

0.028

♦8

0.037

♦42

-

0.059

♦127

' Controlled fay ISP.

k Ealaalon llaltt of 0.035 Ib/MMBtu at 12 percent CO,. ' No Halt for Berylllua Mas 7.3 x 105 Ib/hr. 4 NO, aalsslona llalt I* 0.7 lb/HH8tu. ' SO, Halt Is 0.6 lb/HHBtu. N/T ■ Hot Tested. NO ■ Not Detected.

B 01

cT B

BJ 3

Table 5-7. Summary of Tests on Hog-fuel Boiler at Champion International Corp., Sartell, MN23 March 12-16, 1990*

Particulate

19.7

24.3

+23

SOx

266

277

+4

Cadmium

0.0025

0.0018

-28

Chromium

0.048

0.0046

-90

Lead

0.050

0.036

-28

Mercury

0.00038

0.00008

+111

Zinc

0.23

3.43

+1,391

* Semivolatile organic samples at 4% TDF were lost in a lab accident; thus, baseline results are not included here. b Baseline - 82% coal, 13% bark, 5% sludge, 0% TDF. e TDF - 80% coal, 12% Bark, 4% sludge, 4% TDF.

supplemented with TDF for secondary tests (Smurfit, Packaging Corporation of America, and Dow Corning Corp.) The other three varied the primary and supplemental fuels dramatically. Port Townsend burned waste wood plus 5 percent oil for baseline, and waste wood plus 7 percent TDF for the rubber test.19

Crown Zellerbach burned waste wood and 12 percent oil for baseline, and waste wood with 11 percent oil and 2 percent TDF for the rubber test.14 Champion International burned 82 percent coal, 13 percent bark and 5 percent sludge for baseline, and for the TDF test, burned 80 percent coal, 12 percent bark, 4 percent sludge, and 4 percent TDF.23

One additional source conducted a test on performance at a waste-wood boiler burning TDF that included results on steam generated and boiler efficiency using the heat-loss method for varied fuel mixes.2 Although the test summary notes that emissions testing was done, the results were not obtained. Nevertheless, one of the conclusions of the test report was that TDF had no environmental disadvantages when compared with the supplemental coal used during the tests.2

5.3.1.1 Particulate Emissions- Particulate emissions increased in all six emission tests reported here. Percent TDF varied from 0 to 15 percent. A comparison of percent change in particulate emissions over baseline is given in Figure 5-2. An emission rate comparison is found in Figure 5-3.

One paper mill, Inland-Rome, in Rome, GA, ran four tests burning varying amounts of wood waste, TDF, biological sludge from the plants secondary effluent treatment system, and coal.2 One TDF test was run at 7 percent TDF and 93 percent wood waste; particulate emissions were similar to baseline.2 Another test was run with 12.8 percent TDF, 12.1

percent sludge, and 75.1 percent wood waste; particulate increased slightly over baseline in this test, but did not exceed permitted levels.2 The test boiler at this facility shares the ESP and stack with three other power boilers (also burning wood waste and/or pulverized coal and TDF); therefore, the incremental increase due solely to the change in fuel mix at the test boiler could not be determined.2

5.3.1.2 Sulfur Dioxide Emissions. Sulfur dioxide emissions also increased somewhat in all tests. Figure 5-4 shows emission rate changes for S02.

5.3.1.3 Nitrogen Oxides Emissions. The nitrogen oxides (N0X) in Dow-Corning•s emissions decreased about 50 percent between their highest and lowest burning rates. Packaging Corp. of America's results show a 5 percent drop in N0X. Smurfit and Champion did not test for nitrogen oxides. A summary of nitrogen oxides tests is given in Figure 5-5.

5.3.1.4 Carbon Monoxide Emissions. Emissions of carbon monoxide increased in the one data set comparing baseline to data with TDF. This comparison is graphed in Figure 5-6.

5.3.1.5 Heavy Metals and Eolvnuclear Aromatics (PNA). Zinc emissions are frequently mentioned as an element that could increase significantly when burning TDF, because of the zinc content of the rubber. Because zinc oxide has a small particle size, sources controlled by scrubbers have particular concern that the zinc oxide will escape the control device. ESP's, on the other hand, would be well suited to pick up a small metallic particulate. Zinc was measured at all six plants evaluated here. Data on zinc emissions show that in all five data sets where comparison to baseline levels was available, zinc emission rates did increase,often dramatically. Figure 5-7 graphs zinc

Plant

10% TDF

18% TDF

A-Port Townsend; ■■••lint Included 5X oil; «cni&er controlled

•-Crown Zellerbach; ■••«line Included 12X oil; TDF tett Included 11X oil; ScrUbber controlled C-S«urflt newsprint - acrtiiber controlled. D-Packlng Corp of Aaerlct; ESP controlled. I-Oow Corning; ESP controlled.

F-Chaanplon; Baseline - 82X coel, 1JX bark, SX sludge; TDF Included BOX coal, 12X bark, <X sludge.

Figure 5-2. Percent change of particulate emissions over baseline (Ot TDF) in wood waste boilers burning TDF.

Baaelne » 82% coal, 13% baifc, 5% akidge; TDF teal-80% coal 12% bark, 4% aludge. 4% TDF.

Figure 5-3. Particulate emission rates from hog-fuei boilers burning TDF supplementally.

toy.

Dow-Comjpg

Woodwul* +10% TDF; ESPconlratod

Port Townsend

Woodwatts + 5% 0»; aciubber condoled.

Crown Zellerback

Baaelne Included 12% ol; TDF tart Inducted 2% TDF + 11% ol; aciubber controlled.

Smurfit

Woodwaata + 1% TDF; Woodwaata + 1.5% TDF; aciubber controlled.

Packaging forp of America

Woocfcvaate ♦ 1.6% TDF; ESP controled.

Champion

Baaelne » 82% coal, 13% baifc, 5% akidge; TDF teal-80% coal 12% bark, 4% aludge. 4% TDF.

Cfl o

5"

Figure 5-3. Particulate emission rates from hog-fuei boilers burning TDF supplementally.

%7DF

Sinurtt Plant PaefcagingCafpotAfiMrica Champion Plant

%7DF

Sinurtt Plant PaefcagingCafpotAfiMrica Champion Plant

Figure 5-4. Change in emission rate of SO, over baseline (0% TDF) at varied TDF input rates for hog-fuel boilers.

f 80

20 0

f 80

20 0

---

107.08

' 114J8

-----«

o

-

1

%TDF

amurttNawaprint Pacfcaglng Cap ot America

%TDF

amurttNawaprint Pacfcaglng Cap ot America

Figure 5-5. Change in emission rate for NOx over baseline (0% TDF) at varied TDF input rates for hog-fuel boilers.

150

-

O

147.23

125

111.08_________

O

75

-

50

-

2S

-

0

I

1

%TDF

1.5X

Packaging Cocp of Amahca

Smurill Plant

%TDF

1.5X

Packaging Cocp of Amahca

Figure 5-6. Change in emission rate of CO over baseline (0% TDF) at varied TDF input rates for hog-fuel boilers.

3.82

48.8

Port

Towns* nd

(ScrubbM)

3.43

Dow Corning m

Port Townsend m

Crown Zellerbach

Champion

Packaging Corp of America

Figure 5-7. Change in zinc emission rates when burning TDF at six pulp and paper plants.

emission rates and denotes whether control at each facility is by scrubber or ESP.

Washington State tested two (Port Townsend and Crown Zellerbach) waste heat boilers controlled by venturi scrubbers for PNA's, both at baseline (no TDF) and while burning TDF.24 Crown Zellerbach found emissions of zinc to be seven times higher when tires were burned, and emissions of arsenic, chromium, cadmium, and barium to increase 100 percent.16 Port Townsend found zinc concentrations increased almost 17 times when burning tires, but other metals had decreases or smaller increases.17 The high zinc increase at Port Townsend may be attributable to the higher tire input percentage, whereas the higher emissions of other metals at Crown Zellerbach may be because of the 11 percent Btu input provided by oil.16,17 Figure 5-8 shows percent change in metals emissions other than zinc for both Washington paper facilities. Zinc emissions were shown in Figure 5-7.

Emissions of all PNA's from Crown Zellerbach decreased, while those from Port Townsend varied.16,17 Figure 5-9 compares percent change of specific PNA's from the two companies.

5.3.2 Control Techniques

Of the seven plants where the control device was known, three controlled emissions with venturi scrubbers, three controlled emissions using ESP's, and one controlled emissions with one scrubber and one new ESP on two separate boilers. In total, 13 boilers were located at these seven plants. Four of the individual boilers were known to be controlled by venturi scrubbers, and nine were known to be controlled by ESP.

Arsenic Copper

Iron Nickel

Chromium Cadmium

+8292

Iii*48

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