# Boih Emissions



# Sulf.ur capture 

# in combination 

# bark boilers

Arutll

### V. Someshwar 

### and Ashok 

### K Jain



## ABSTMCTA 

## review 

## of sulfir 

## dioxide emission hta for eight

com

## bimtion bark boilers in conjunction with the sulfir contents 

## of the fieh reveahsignificantsu@r 

## capture rangingfrom 10% to 

## over 80% 

## within the 

## soldash phase. Wood

## ash characteristicssimihr to 

## activated carbon as 

## well 

## as the significant wood 

## abalkali ox& 

## and carbomte fractions are believed responsible for 

## the su@r 

## capture. Su@r 

## emissions from combination bark-fossilfieljring are correhted to 

## the su@r 

## inputper ton 

## ofbark or 

## wood residue jred
KEywoRDs:

## Ash, bark, boilers, emission,gas scrubbing, sulfir dioxi&.

oilers which can burn bark and 

# Bother wood residues such as saw kerf, sander dust, and wood fines either alone or in combinationwith fossilfuelsfind wideuse atforest product manufacturing facilities. The ashes resulting from wood residue combustion typically contain a significantfraction 

### of oxides and carbonates of alkali metals such 

### as calcium,potassium, and magnesium. Although there is no 

### literature documentation,wood residue ash can capture some of the sulfur dioxide released with the eo-firing of sulfur-containing fossil fuels such as coal orfueloilwithwoodresidue.When

a wet scrubber follows the combination bark boiler, this sulfur dioxide removalby alkaline wood ashbecomes

even more prominent. This paper reviews available data

on sulfur capture in combinationbark boilers and explores the reasons 

### for 

### this capture. Duringcollection

### ofmuch 

### of this data there was no systematic effort 

### to identifythe mass balance on sulfur. The study compares data on stack 

### sulfur dioxide emissions from combinationbark boilerswith the sulfur content of fuels eo-fired with bark

orwood residue

### toestimate the extent of fuel 

### sulfur capture in wood ash. There is 

### also supporting data on gassolid sulfur capture by alkaline fractions 

### of other fuels.



### Wood residue composition



### Table 

### I presents the analyses

### of some selectedwood residues burned 

### as fuel

as well as analyses of ashes resulting

Someshwar is senior research engineer and Jain is regional manager with National Council of the Paper Industry for Air and Stream Improvement, P.O. Box 141020, Gainesville, FL 32614. fromwoodresidue burning 

### (I,2).Typical wood residues contain nearly 2- 4% ash. Over 

### 60% of these ashes are oxides and carbonates 

### of calcium?potassium, and magnesium. When cofiring with oil, coal, or any other sulfur-containing fuel,these alkalioxides and carbonates can reactwith the sulfur dioxide and 

### sulfur trioxide resultingfrom fuel combustion. 

### Figure 1 

### is a simple material balance which demonstrates the potential for 

### sulfurcapture in a combination boiler. As an example, consider firing

a mixture of 30% coal and 

### 70% bark (heat input basis) in a 500 

### x lo6 Btuh combination boiler. Assume the coal has 1%sulfur and a heating value of 12,500Btu/lb,andthebark has 0.025% sulfur, 2.0%ash (of which 

### 50% is calcium oxide), and a heating value of 

### 8600 Btu/lb. The molar ratio of calcium to 

### sulfur in the fuel would be approximately 1.9. The alkali metal concentrationin the coal-bark combination fuel 

### is clearly in excess.As the results of 

### this paper 

### will show, there will be capture of over 50% 

### ofthe combined fuel 

### sulfur in the combustion ashes. Calcium 

### to sulfur mole ratios ranging from 1 

### to 3 in lime-limestone, wet or 

### dry, flue gas desulfurization systems have historicallyyielded well

over 

### 50% sulfur dioxidecapture.



### Sulfur capture 

### in wood residue boilers-prior evidence

The sulfur content of bark and other wood residues is very small. One report indicates that the sulfur content 

### of 14 different wood samples ranges

Vol. 76, No. 7Tappi Journal 

### 1791. Sulfur balance for a combination bark boiler 2. Percentage sulfur retention vs. Ca/S ratio for lignite samples

30% coal, 70% bark Coal: 1.0% S Bark O.O25%S Flue gas 99,000 dry std. it3 per min @ 4% 0 120 ppm SOp (60 Ib/h S) 

# 4

Economizer& ESP ash

CP



## - (70 Ib/h S)

Coal: 6 ton&

(120 lb/h S)

Bark 20 ton& 

# 4 1 -- - -.C!Bottom ash (10 Ib/h S)

from 0 to 

### 0.1% on 

### a 

### dry weight basis (3). The average is approximately 

### 0.028%.

### A field study by 

### NCASI to quantify the fate of 

### this small amount of 

### sulfur in wood residue, when only the residue was fired in four boilers, showed that just over

### 5% 

### of the sulfur contained 

### in the residue was emitted

as 

### sulfur dioxide. The remaining sul

### furwas 

### in the bottom and fly ash (1). Table

### I also showsthat the ash from wood combustion typicallycontains less than 

### 3.2% sulfate expressed as 

### sulfur trioxide. During several 

### tests on combination bark-fossil fuel boilers, however, analyses for soluble sulfate content of particulate matter caught

on filter papers showed large metal sulfate fractions (4,5). 

### EPA Method 

### 5

was the 

### test procedure. In the case of 

### two boilers, both of which fired wood residueand oilin variouscombinations, soluble sulfates comprised from 

### 35% 

### to 76% of the total particulate catch 

### (4). Furthermore, 

### in one of these boilers from 37% to 

### 54% of the soluble sulfates were present 

### asmetal sulfates, the remainder as free sulfuric acid. In the outlet of a third oil-bark combination boiler firing a 2.2%

### sulfur oil, the 

### 180 July 1993 Tappi Journal 50' '

CalS RATIO OF LIGNITE SAMPLE

I 1. Analyses of some selected wood residues burned as fuel

Item Western Jack pine Birch Maple hemlock

Ash Volatile Fixed carbon

Carbon Hydrogen Sulfur Nitrogen Ash Oxygen (by difference) Heat value,Btu/lb dry

TiO, Sulfate as SO, Proximate analysis, YO 2.1 2.0 74.3 78.5 23.6 19.2

Ultimate analysis, % 53.4 57.4

5.9 6.7 <0.2 c0.2

0.1 0.3 2.0 1.8 38.6 33.8 8930.0 8870.0 Ash analysis, Yo
16.0 3.0 6.3 0.0 5.0 2.9 51.6 58.2 4.9 13.0 5.5 4.2 1.6 4.6 2.8 2.9 4.1 6.6 3.1 1.3 0.2 Trace 2.6 3.2 4.3 76.1 19.6

50.4

5.9 <0.2

0.5 4.1 39.1 8190.0

9.9 3.8 1.7 55.5

1.4 19.4

1

### .o 1.1 5.8 2.2 Trace 1.4 2.5 72.0 25.5

53.6

5.8 <0.2

0.2 2.5 37.9 8885.0

10.0 2.1 1.3 53.6

9.7 13.1

1.2 2.1 4.6 1.1 Trace 1.4Sulfur caDture in bark-coal boilers

8-

4- P 

# !2 2 

# a 8

cl z

Y K a

a m LL 0 

### z 0

z

rn 

# 5

E 0 2

K a LL 4 a rn -60 8

W K 3In 4 0 K 3 LL -I -40 

## 2 d 12 1 180

\ \ \\ 

# / \\\

\



## i

0' 

# '
20

0 10 20

SULFUR IN COMBINED FUEmON WOOD RESIDUE, Ib Sulfur capture in bark-oil boilers

14

P

W W LL 

## - d 

# d

P 10 

### z

Y K
m 

### a

a 

## B


# 5

3

52 z O6



### z

rn 0 

## ur

K a

a fn 100

80

\
60

40

20

0 0 10 20 30

SULFUR IN COMBINED FUEVTON WOOD RESIDUE, Ib

total sulfate concentrations ranged from 2.9%to 25.5%

### of the total sulfur emissions (5). The metal sulfate fraction 

### of the total sulfate emissions in this case ranged from 53% to 92%. Clearly, significant sulfur capture in bark ash was occurringin these combination boilers. One investigator (6) reported that the substitution

### ofup

### to 13% byweight of hogged fuel by coal in a boiler with emissions controlled 

### by multiclones andtwoparallelwet scrubbers resulted in a negligible change in the level of sulfur dioxide emissions. At comparable steam production rates of about 160,000 lbh, the coal substitution increased sulfur dioxide emissions from

zero 

### to only 

### 6 ppm. Although the coal sulfur content and heating value are unknown, at 13%by weight coal substitution a coal with sulfur content in the range of 

### 0.5 to 3.0%and heating value of 12,500Btu/lb should have resulted in nearly 100400ppm of sulfur dioxide in the stack at 3%oxygen. 

### capture 

### ita other 

### bodem

The literature also documents sulfur capture by the alkaline ash 

### of other fuels such 

### as coal, oil, and municipal refuse. In an analytical study by the 

### EPA 

### to assess the potential for sulfur retention in varioustypes of coal-fired boilers, significantfractionsof the 

### sul

### furwere shown

### to be bound 

### as calcium and sodiumsalts (7'). For example,

### Fig

### ure 2 shows how a significant sulfur retention occurs in lignite coal which contained about 20% lime in the ash (7). Equation 1 provides the relationship for this curve:

% sulfur retention = 74.1 (Ca/S)o.22 (1) Other investigators (8) showedthat 

### sulfur retention in coal fly ash was a function of the alkali metal oxide content of fly ash. 

### For pulverized coalfired boilers with electrostatic precipitators they estimated sulfur dioxide removal due to retention in the fly ash to range from near zero for a coalwithvery low alkalinity

### to greater than 40% for a 0.5% 

### sulfur coal with 10% ash and 35% total alkali metal content in the ash. From available data on the incineration of municipalrefuse which 

### usually contains between 0.10% to 0.15% sulfur, one study (9) concluded that the stack only released one fourth of the 

### sulfur as 

### sulfur dioxide. The remaining 

### sulfur was fixed in the grate and fly ashes as alkaline sulfates.



### As mentioned earlier, evidence 

### of 35- 76% sulfate fractions in ashes resulting from bark or wood residue co-combustion with oil, both as free sulfuric acid and as alkali metal sulfates have been found(4, 5). These sulfates most likely originate as 

### sulfur trioxideresultingfromoxidationof sulfur dioxide, just as in the formation 

### of sulfuricacid during oil 

### or coal combustion(l0,ll). The extent of sulfur trioxide formation required 

### to explain the level of sulfates present in combination bark boiler ashes, however, 

### far exceeds that typically associated with oil 

### or coal combustion alone. There must therefore be other mechanisms of sulfur dioxide oxidation involving the bark ash.

Vol. 76, No. 7 Tappi Journal 

### 18

### I_I -> II. Combination boiler source and fuel description

Total Fossil Fossil YoHeat input Yo Heat input Measured heat input, bark or wood fossil Other SO, emissions, Code x106 Btu/hr type 

### s, % residue fuel fuels Ib/lO6 Btu

Mill A 760 Mill B 461 to 474 Mill C 274 to 475 Mill D 239 to 318 Mill E 190 to 320 Mill F 231 to 585 Mill G 179 to 310 Mill H 198 to 258 Coal Coal Oil Coal Oil Oil Coal Oil 1

### .oo 0.9!5 2.1!5 1

### .oo 2.1!3 2.1!3 0.40 2.20 45 to 73 53 to 81 64 to 84 9 to 40 80 to 87 16 to 79 9 to 19 41 to 81 27 to 55 19 to 47 16 to 36 22 to 86 13 to 20 21 to 84 72 to 86 19 to 59 None None None NCG, gas None None Sludge None 0.12 to 0.76 0.06 to 0.36 0.13 to 0.44 0.62 to 1.88 0.43 to 1.84 0.43 to 1.84 0.14 to 0.41 0.05 to 0.61

I

5. Sulfur capture in boilers with venturi scrubber 6. Summary of gas-solid sulfur capture in combination boilers



# tD

- 0 40 80 120 80

i9 

### d 60
3I0

40 

## 2

-I 3 rn n a

a

20

I

SULFUR IN COMBINED FUEVTONWOOD RESIDUE, Ib

Judging by thewaywood ash forms in bark boilers, it is reasonable to expect it to possess properties similarto that of activated carbon. Pyrolysis or cabonization 

### of several carbonaceous materials includingsawdust andwood forms activatedcarbon (12).Wood ash has a small particle size and low density similar 

### to activated carbon (13). The carboncontentofwoodash ranges from 1% in fluidized-bed combustion to 70% in inefficientburners, 

### a typical range being 

### 530% (14).The high degree 

### of carbon in wood ash is further evidence of the carbonizationprocess 12-Iw 3 u. 0 W 

# f

88

$3

54 

### a

z 0



### z

u) 0


### u,

a 3 u. J 3 u)

0 100

80

i9

60 

# $

3I0

40 

## 2

-I 3 u) n a

a

20

0 0 40 80 120 160

SULFUR IN COMBINED FUEVTONWOOD RESIDUE, Ib



# - 111. Best fit curves 

## 1

xvs. Y, r2 log

### x vs. log Y2 r2 Figure

3 Y, = 0.52X 

### - 1.29 0.94 Y, = 155.9X-058 0.56 4 Y, = 0.44X 

### - 0.174 0.90 Y, = 113.9X-044 0.46 5 Y, = 0.44X 

### + 3.18 0.31 Y, = 80.7X-009 0.08 6 Y, = 0.45X 

### - 0.55 0.91 Y, = 128.5X-050 0.51

## II I

that occurs during wood residue 

### corn- properties of several microcrystalline bustion. carbonaceous materials including acActivatedcarbon

### isaverygood cab- tivated carbon.Using experimentalrelyst forthe oxidation of 

### sulfurdioxide sults of several investigators, they to sulfur trioxide. One group (15) re- concluded that even at elevated temviewed the absorptive and catalytic peratures (representative of sulfur

### di182 July 1993 TappiJournaloxide-bearing flue gases) activated carbon can absorb a considerable amountof sulfurdioxidethrough catalytic oxidation occurring on the carbon surface. In addition,the presence of water vapor and oxygen enhance the absorption of 

### sulfur dioxide. Under these conditions, sulfur dioxide converts 

### to sulfuric acid and the acid remains on the carbon (15). The activated carbon-like wood ash has the added advantage of being able 

### to neutralize the acid formed from 

### sulfur dioxide oxidation due 

### to the significant concentration of alkaline oxides and carbonates in the ash. Otherpotential mechanisms 

### for sul

### fur capture in wood ash may include sulfur dioxide reaction with calcium oxide in the ash with concurrent oxidation to sulfate. There can also be oxidation of sulfur dioxide 

### to sulfur trioxideby metal oxidespresent in the wood ash (in addition to the action of carbonaceous materials) and subsequent capture by alkalinewood ash fractions.



### Sulfur capture in combination bark boilers

For the study we obtained data on sulfur emissions from combination bark boilers from mill 

### tests (compliance and otherwise) available 

### to NCASI as well as other sources of published information. The following presentation provides data on capture

the solid ash phase (pre-scrubber 

### or boilers without scrubbers) or into both the solidand liquidphases (boilerswith scrubbers). 

### Table I1 provides a summary of the eight combinationboilers used to collect the data including the fuelmix in each boiler, fuel sulfur contents, and range of measured sulfur dioxideemissions.The percentage sulfur content of bark or wood residue when measured, was always below 0.04%. Figures 3-6 areplots of the data in units of pounds of sulfur emitted as sulfur dioxideper dryton 

### of combined fuel, 

### Y,, vs. pounds of sulfur in the combined fuel per dry ton 

### of bark 

### or I of volatilized sulfur compounds into wood residue 

### (X). In addition, these figures provide on the second y 

### axis the reduction in potential or stoichiometric sulfur dioxideemissions(alternately, the percentage sulfur captured),

### Y,, as a functionof

### X. Table I11 showsthe best fit curves 

### for 

### X vs. 

### Y, and log

### X vs. logy, as well as the 9 values for theregression 

### fitsin each of these figures. One shouldnote that 

### forbarks with similarcalciumcontentstheinverse

### of 

### X is proportional to the more familiar calcium 

### to slllfur mole ratios used extensively

### for correlationin the area 

### of flue gas desulfurization.



### Bark-coal combustion Mills A, 

### B, and 

### D fired significant amounts of coal along with bark in their combination boilers. Mill 

### D also fired some natural gas and pulp mill vent gases (NCG) containing sulfur compounds.Figure 

### 3presentsthe data 

### for sulfur capture inbark-coal boilers. Mills

### A and 

### B boilers had electrostatic precipitators (ESP). Data for the Mill Dboiler corresponded

### to the inlet to a spray dryer absorber. In the case of the Mill Dboiler,the sulfur inputfrom pulp mill vent gases was sigmficant 

### (4.). Table 

### 111 shows that 

### Y, in Fig. 

### 3 correlated ratherwellwith

### X(9=0.94). In addition,thepercentageof captured stoichiometric 

### sulfurranged fromover 

### 20% 

### to about

### 70%. Note,however,that the sulfurcontentsof coalsfired in the three boilers fell within a relatively

narrow range of (see Table 11) approximately 1%.



### Bark-oil combustion Mills C, 

### E, F, and 

### H fired fuel oil in addition to bark or wood residue in their respective combination boilers. Figure 4 shows the relationship between the pounds of sulfur in stack emissions and the pounds of sulfur in the combined oil-bark feed. Mills C and 

### E boilers had an ESP

### for particulate control. The Mill F boiler had a 

### dry scrubber. The EPA studied 

### it extensively (5, 16). The data of Fig. 4 for the Mill 

### F boiler correspond 

### to the boiler outlet location before the dry scrubber. The Mill 

### H boiler had a venturi scrubber. There was one test at a location before this location,however, and 

### this datum is included in Fig. 4. This figure also conhssome of the trends observed earlier in Fig. 

### 3. 

### Y, correlated rather satisfactorily with 

### X, especiallyfor low values 

### of 

### X (9 = 

### 0.90, seeTable 111).The percentage of sulfur captured ranged from nearly 10% to over 80%. As in the case 

### of the coal-bark boilers,itis necessary

### tonote that the sulfur contents

### of oil burned in all four of these oil-bark boilers (see Table 111) fell within a fairly narrow range 

### of approximately2.2%.



### *Solid 

### md gadiqdd
sulfur capture Figure 

### 5presents data 

### for sulfur capture in Mills G and 

### H boilers where the information came from locations following 

### a wet venturi scrubber. For the period 

### of collection of these data, there was no alkali addition to the scrubbing solution in either instance. The Mill 

### G combination boiler burned bark and coal in addition

### to smallquantities 

### of sludge.

### Ithas a dual-alkali wet venturi scrubber. The Mill 

### H boiler burned oilwith wood residue and used a variable throat venturi scrubber to control particulate emissions. 

### Sulfur removal efficiencies are fairly high

even atlevels of sulfur input thatwere significantlyhigher than those shown earlier 

### in 

### Figs.3 and 4. Correlationsof 

### X vs. 

### Y,, however, are rather weak (9=0.31,see Table 

### 111).



### S-T Figure 6 summarizesall the data corresponding to in-furnace and prescrubber sulfur capture 

### in the three coal-wood residue and four oil-wood residue combination boilers. In this figure, the sulfur in combined fuel 

### included sulfur from various sources such asfuel oil, coal, and sludgeaswell

as NCG in some cases. The pattern of sulfur capture appears independent of the origin 

### of the fuel 

### sulfur.As seen from Table 

### 111, 

### Y, correlated fairly well with 

### X (9 = 0.91).

Vol. 76,No. 7 Tappi Journal 

### 183

# BoilerEmissions lZ-z-2=--x-x 

## -:= -Y In using relationships derived in the study for 

### Y, and 

### Yzvs. 

### X for other combinationboilers, it is necessary 

### to note 

### two assumptions that remain. 

### First, only the ratio of 

### sulfur 

### to wood residue in the combined boiler fuel affectsthe 

### sulfur capture mechanism. There was no consideration 

### of other parameters of combustion such as excess 

### air,boiler load factor, percentage unburned carbon in ash, etc. There

was 

### also no consideration of the potential 

### sulfur capture capabilities 

### of coal ash itself. Second, in using the ratio 

### ofpounds 

### sulfurin combinedfuel feed to tons wood residue 

### as an independent parameter, the ashes from burning all wood residues were assumedto have aboutthe same amount of alkali metal oxides and carbonates per ton of wood residue. Obviously,

### a more detailed study would be neces

### sary 

### to determine more precisely the influenceofthese other factorsonbark ash 

### sulfur capture.



### Conclusion

Data on gas-solid 

### sulfur capture in seven pulp and paper millcombination bark boilers showed that a sigmficant amount 

### of the 

### sulfurthat would otherwise have resulted in 

### sulfur dioxide 

### or 

### sulfirrtrioxide emissions was captured within the boiler.

### A regression line 

### for the data corresponding to these seven boilers gave a linear relationship of the 

### .form 

### Y= 0.45X - 

### 0.55, where 

### Y is the pounds 

### sulfur emitted per ton of combined fuel and 

### X is the pounds 

### sulfurin combinedfuelper ton ofwood residue. Consideringthe high carbon content and porosity of wood residue ash and its mode of generation, the



# The Ha2 

# Pages publishedby Emlands Publishing Inc. The 

### Haz Pages..



## .a yellow-pages style directory exclusivelyfor hazanlous and toxic materials management With the Haz Pages, you’ll have a comprehensive, easy-to-use source of products and services for the control of hazardous materials right at your fingertips. The 

### Haz Pages brings together waste treatment and disposal, air quality, wastewater, groundwater, health and safety, transportation, remediation, laboratories, equipment, software, consultants, cleanupfor spills, instrumentation,ASTAJST, industrial hygiene, containment, and more 

# - all in one easy-to-use volume. 

### Order Number: 13HAZP 

### Spec/a/ TAPPl

### Pr/ce:$49 (members and nonmembers) plus shipping and handling 

### To order call T’APPl’s toll-free Service Line at 1-800-332-8686 (US) 

### or 1-800-446-9431 

### (Canada.

404446-1400. Ask 

### about 

## our volume 

### discounts! 

# -

TAPPI PRESS Outside US 

### or Canada, 

### cal

# 1 authors postulatethatthe ashbehaves similarly to activated carbon at elevated combustion temperatures. Thus

### it absorbs considerableamounts 

### of 

### sulfur dioxide from a gas stream and catalytically oxidizes it to 

### sulfur trioxide or sulfuric acid. Subsequent reaction of acid with the high alkali content of the ash yields the high levels of metallic sulfates commonly observed in combination boiler ashes. Data 

### on simultaneous gas-solid and gas-liquid sulfur capture from 

### two combination bark boilers equipped with wet scrubbers show sigmficant capture efficiencies even 

### at high sul

### furto bark ratios.



### Literature cited

1. “Informationon the Sulfur Content ofBark and Its Contribution to Sulfur Dioxide Emissions When Burned as a Fuel,” NCASI AtmosphericQualityImprovement Technical Bulletin No. 96, NewYork, 1978. 2. “Steam, Its Generation and Use,” Babcock and Wilcox Co., New York, 1963. 3. Nunn, A. B., “Preliminary Compilation of Data for Emissions fromWood-Fired Boilers,” TRW Environmental Engineering Div., Report prepared for EPA Contract # 68-02-2613, Task no. 30,1979. 4. “SulfurCapture in CombinationBark Boilers,’’ NCASI Technical Bulletin No. 640, New York, 1992. 5. Cheney, J. L., Winberry, W.T., Pleasant, J. M., Grotecloss, G. B., AnalyticalLetters

6. Vosler, G. L., Tappi J. 68(10): 66(1985). 7. “Sulfur Retention in Coal Ash,”US. EPA600/7-78-153b,Washington, 1978. 8. Davis, W. J. and Fiedler, M. H., JAPCA 32(4): 395(1982). 9. Kaiser, E. R., JAPCA 18(3): 171(1968). 10. Jaworski, R. J., APCA23 No. 9: 791(1973). 11. Crocker, B. B., Chem. Eng. Prog. 71(3): 83(1975). 12. Hassler, J. W., Activated Carbon, Chemical Publishing Go., NewYork, 1963,Chapter 8, p. 171. 13. Campbell,A. G., Tappi J. 73(9): 141(1990). 14. Greene, T. W., Wood Ash Disposal and Recycling Source Book, OMNI Environmental Services, Beaverton, 1988. 15. Hartman, M., Polek, J. R., and Coughlin, R. W., 1970, Chemical Engineering Progress SymposiumSeries, McGraw Hill,

16. Winberry, W. T., “Primary Sulfate Emissions Measurements for a Hogged-Fired Boiler,”U.S. EPATechnical Directive 3.3- 22, Washington, 1978. 12(A?),pp. 155-167 (1979).



### w,p.7.

Received for review Sept. 17,1992.
Accepted Feb. 11,1993.



### 184 July 1993 Tappi JournalPaul Earl and Paul Rostek Sterling Pulp Chernicah, Ltd.
Kevin Dunn and Jean-Claude Pate1 Wheelabrator Water Technologies,Inc.

Editor's reply:



### In piecing together "The pulp mill of the future," it was soon obvious that a book could be written on the topic. The intent was to gather insights from pulp manufacturers, consultants, suppliers and researchersworldwide, including the United States, Canada and Scandinavia. What we ended up with-and presented-was simply one possible view. No bias was intended, butit was clear there would be differing views and that we would not cover all possibilities. The Bleach Filtrate Recycle (BFRTM) process is certainly

an innovative technology that will likely be an important part of some pulp mills in the future. We would welcome other comments and views

on technologies and issues that will have a significant impact on thepulp mill of the future. 

### -Don 

### Meadows Editor Tappi Journal
Author recognition



### As 

### an additional acknowledgement to my article in the November issue (78[11]:121.[1995]) of 

### TappiJournal regarding catalytic oxygen-alkaline pulping, 

### I would like to thank my friend Dr. Vladimir Leshokhin of Chester, 

### NY, for his help in preparing the manuscript.

-Dr. Emil Germer All-Rwsian ScientiJic Research Institute ofthe Pulp and Paper Industry St.Petersburg, Rwsia

Pho.to missing



### Because of a printer's error, the photo of Elliot Rohde scheduled

### torun with his editorial "Lessons of business" on p. 

### 240-4 of the October 1995

- - 

### Tappi Journal (78[10]: 240-4[19951) did not appear. 

### An editing mistake also occurred in the finalparagraph of the first page ofthe editorial, which was originally titled "Productivity and profitability are today's corrugated watchwords." As submitted, the second half of the paragraph should read: "Recycling of corrugated combined board and of paperboard waste is carried on; in addition chemicals within the plant are included in the proper recycling and waste disposal processes." 

### Tappi Journal apologizes for the errors.

Conference report error


### The August 1995 conference report "Chemical Recovery Conference emphasizes high solids firing and mill system closure" (78[8]:203 [1995]) contained an error under the heading "Recausticizing." Kurt Skrifvars,vice president ofAhstrom Recovery Inc., was affiliated with another company in the report. Skrifvars presented results from Wisaforest in Finland at the 1995 Chemical Recovery Conference, April 24-27, held in Toronto, ON, Canada.

Figure correction


### Afigure in the July 1993paper "Sul

### furcapture in combinationbark boilers" (76[7]:179[1993]) was incorrectly published. The x-axis in Fig. 6 should have been the same as in Fig. 4. Thex-axis, which showedvalues of 0, 40, 80, 120, and 160 lb for sulfur in combined fueVton wood residue, should have shown values of 0,7.5, 15.0,22.5, and 30.0 lb.

International Notebook clarification


### The September 1995 International Notebook (78[9]:48[1995]) reported that Champion Papel e Celulose (CPC) had approved the building of a printing and writing paper mill in Mato Grosso de Sul State in Brazil. Champion International states that reports of this nature areincorrect, that the company has made no such decision. Champion maintains that the goals of debt reduction and increased returns to shareholders must be accomplished before new major investment is authorized.

Vol. 78, No. 12 Tappi Journal 

### 13