papermill waste in afbc by fwc

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Paper No. FBC99-0157

Test Study of Salty Paper Mill Waste in a Bubbling

Fluidized Bed Combustor

Proceedings of the 15th International Conference on

Fluidized Bed Combustion

May 16 - 19, 1999

Savannah, Georgia

Copyright 1999 by ASME


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Test Study of Salty Paper Mill Waste in a Bubbling Fluidized Bed Combustor

Song Wu and Kumar M. SellakumarFoster Wheeler Development Corporation

Livingston, New Jersey

P.K. Chelian and Charles BleiceFoster Wheeler Energy Corporation

Clinton, New Jersey

Ian ShawMacMillan Bloedel Limited

Burnaby, British Columbia, Canada

ABSTRACT

Foster Wheeler Pyropower Inc. has supplied a 73.7 kg/s bubbling fluidized bed boiler to

MacMillan Bloedels Powell River paper mill (now Pacifica Paper). The BFB boiler wasdesigned to fire a fuel mixture of a mill effluent sludge and a hog fuel (bark) that is

contaminated with seawater. Due to its very high alkali content and low ash content, the fuel

is prone to cause problems such as agglomeration in the fluidized bed.

Foster Wheeler and MacMillan Bloedel took a proactive approach to quantify likely

problems and to identify solutions. A 200 hour-long test program was carried out at Foster

Wheeler Development Corporation in Livingston, New Jersey with the Powell Riverfeedstock.

This paper provides the project background, an outline of the test facility, test matrix, fueland bed material characteristics, followed by a test process overview. A summary of fuel

alkali related agglomeration mechanism in fluidized bed is also included. The paper offers

further observations on in-bed alkali accumulation as well as examinations of different types

of bed material agglomerates found during the tests. A recommended boiler operatingstrategy for preventing agglomeration in the BFB boiler developed based on the test results is

described. These recommendations have been successfully implemented during the start up

of the boiler. The boiler has been in operation since November 1997. Boiler performancetests completed in April 1998 have demonstrated all guaranteed process conditions.

INTRODUCTION

In 1996, Foster Wheeler Pyropower Inc. was awarded a contract to supply a bubbling

fluidized bed boiler to MacMillan Bloedels Powell River mill (now owned by Pacifica

Paper). The boiler is rated at 73.7 kg/s steam at 6205 kPa and 477 C. It is the largest bio-mass fired bubbling fluidized bed boiler in North America. The BFB boiler is designed to fire

a fuel mixture of bark, primary and secondary mill effluent sludges. In addition to a high

moisture content and a low heating value, the fuel is also contaminated with sea salt.


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Due to low ash content, the relative concentration of the alkali in the ash is very high. Thisindicates the potential ash related operating problems such as agglomeration in the fluidized

bed. Facing this difficult fuel, Foster Wheeler and Macmillan Bloedel took the proactive

approach. Studies of Powell River fuel and ash behavior were embarked co-currently with

the project engineering and construction activities.

Results of initial laboratory sintering tests by Foster Wheelers Karhula R&D Center

indicated that all salty ashes generated from Powell River fuels started to agglomerate at

temperatures as low as 600C. These simple preliminary screening tests were performed byfirst ashing fuel samples and then heating this ash and bed sand in crucibles. Therefore, a

test study of Powell River fuel on the fluidized bed combustion pilot plant PF-100 was

proposed to evaluate the impact of alkali on the combustion process, specifically,agglomeration of bed material due to accumulation of alkali in the bed. Based on the test

results, recommendations would be formulated for the Powell River BFB boiler.

TEST OVERVIEW

Test Facility

The test unit is a pilot model of a fluidized bed combustor that can be operated in either

circulating fluidized bed (CFB) mode or in bubbling fluidized bed (BFB) mode. It has a heat

input capacity of approximately 30 kW. In the CFB mode, larger solid particles are separatedfrom the gas in a hot cyclone and the collected solids are transferred back into the combustor.

In the BFB mode, the primary cyclone is bypassed and all the gas goes directly to the dust

cleanup cyclones downstream. A schematic of the test unit is shown in Figure 1.

Temperature and pressure measurement devices are placed at various locations in the system.A continuous emissions monitoring (CEM) system determines the levels of O2, CO2, CO,SO2, and NOx in the flue gas. Data from these devices are acquired by a computer and

recorded automatically.

Fuel Handling and Pretests

The as-received hog fuel contains 2- 6 long pieces. To ensure smooth feeding, all the hog

fuel was screened and only the portion passing through the sieve was used for the pilot

tests.

The screened hog was still difficult to handle. The wood chips bridged wherever the flow

was restricted, such as at the bottom of a hopper. After experimenting with numerousoptions, an agitating feeder was chosen for the hog fuel. The feeder has a feed screw that

covers the whole length of the fuel hopper bottom.

The fuel has a very high moisture content (over 60%). The fuel feed system operated well,

irrespective of moisture content in the fuel. However, the high fuel moisture has caused

excessive bed temperature swings during the pretests. This problem was solved by partiallydrying the fuel to reduce the moisture content from approximately 60% to about 20-30%.


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Several shakedown tests were carried out in preparation for the formal testing. During thesetests several fuel handling and operation problems were solved.

Test Matrix

Four tests were conducted. The test conditions are given in Table 1.

Table 1 Test Matrix

Test # 7-7-2 7-7-3 7-7-4 7-8-1

Test Duration, hr 48 12.5 26.5 100

Fuel Hog Hog Hog Hog + Sludge

Nominal Bed Temp.C 740 850 790 780

Primary Air Velocity, m/s 1.3 1.3 1.3 1.3

The bed material samples were taken at 4-hour intervals. Each time, approximately 2-3 kg of

bed material was drained from the bed. A sample of prescribed amount was then taken from

the hot drained material. The rest of the bed drain and a replacement of fresh sand of the

equal amount as the bed sample are fed back to the system through a sand-feed hopper.

BED CHEMISTRY FOR AGGLOMERATION

Agglomeration in fluidized bed involves a complex interplay of fuel, bed material and

furnace operating conditions. In boilers firing high alkali fuels, there is a wide spectrum of

potentially low-melting minerals. The melting points of some of the minerals are listed inTable 2 (Miller et al, 1995).

Table 2 Melting Points of Minerals

Group MineralMelting Temp.

C

Chlorides NaClCaCl2KCl

MgCl2

801782

770

714

Carbonates Na2CO3CaCO3K2CO3

8511339

891

Sulfates Na2SO4K2SO48821069

Sulfides Na2S

K2S

1180

470

As discussed in the previous section, sea water contaminated wood wastes contain alkali,

mainly in the form of chlorides. Carbonates and sulfates can also be found in the test fuels,especially in the sludge. The presence of a significant amount of sodium and potassium in the


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sludge was a further concern. Considering the temperature of burning fuel particles, which

can be 100 200 C higher than the average bed temperature, some of these minerals couldmelt and initiate binding activities leading to agglomeration.

In the combustor, low melting compounds or eutectics may be formed. Some of the possible

reactions are:

2NaCl + S + 3/2 O2 +H2O = Na2SO4 + 2HCl (1)

Na2SO4 + 3SiO2 = Na2O*3SiO2 + SO2 + O2 (2)

Salt can also react directly with silica,

2NaCl + 3SiO2+ H2O = Na2O*3SiO2 + 2HCl (3)

The mixture of Na2O and SiO2 can have melting temperature below 800C, and the eutectics

of NaO*SiO2 and N2SO4 can have melting temperatures as low as 635C.

If alkali silicates are responsible for sintering, metal oxides such as CaO, Fe2O3 or Al2O3 in

finely divided form can be added to the fluidized bed to react with alkali silicates (Wall et al,1975, Tamhankar and Wen, 1981). The final end products of these reactions generally have

high melting temperatures.

Clay is a natural mixture of hydrous aluminum silicates (Al2O3*2SiO2*2H2O). Clay, in thevery fine state, has been found to be effective in retaining the alkalis to form high-melting

temperature alkali-aluminum silicates. Dehydrated clay can react directly with NaCl and

H2O:

Al2O3*2SiO2 + 2NaCl + H2O = 2HCl + Na2O*Al2O3*2SiO2 (4)

Kaolin has been used as an additive to fluidized bed incinerators burning salty sludges to

control fouling and sintering. Recent studies of agglomeration in biomass-fired fluidized bed

combustors indicate that ferric oxide (Fe2O3) can be used to replace silica sand and sustain

long-term operation (Grubor, et al, 1995).

TEST RESULTS AND DISCUSSIONS

Fuel and Bed Material Characterization

Test Fuel

Table 3 gives the conventional fuel proximate and ultimate analyses. Table 4 shows fuel ash

chemical analyses. For ash chemical analyses of wood waste fuel, the sample is generated by

low temperature ashing at 550 C. Ash chemical compositions are determined with an X-rayfluorescent analyzer.


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Table 3 Fuel Proximate and Ultimate Analyses

Test # 7-7-2 7-7-3 7-7-4 7-8-1* Sludge

Proximate analysis, % wt. as received

Fixed C. 18.58 19.85 18.15 14.97

VM 49.84 56.79 59.72 54.61 45.35

Ash 2.48 2.43 1.87 4.98 16.76Moisture 30.72 22.2 18.56 22.26 22.92

Total 100.00 100.00 100.00 100.00 100.00

Ultimate analysis, % wt. as received

Carbon 36.27 40.62 42.99 40.94 33.28

Hydrogen 4.02 4.51 4.8 4.5 3.78

Oxygen 26.39 30.08 31.62 26.98 21.58

Nitrogen 0.09 0.13 0.13 0.31 1.49

Sulfur 0.03 0.03 0.03 0.03 0.19

Ash 2.48 2.43 1.87 4.98 16.76

Moisture 30.72 22.20 18.56 22.26 22.92

Total 100.00 100.00 100.00 100.00 100.00

HHV, MJ/kg 14.52 15.96 17.22 15.32 13.19

Cl, % 0.25 0.24 0.31 0.22 0.11

* hog and sludge blended at 10:1 mass ratio

Table 4 Fuel Ash Analysis*

Test # 7-7-2 7-7-3 7-7-4 7-8-1 Sludge

SiO2 38 43.8 36.5 44.3 43.3

Al2O3 9.2 10.1 9.1 16.1 29.2TiO2 0.3 0.3 0.3 0.7 2

Fe2O3 6.1 7.7 12.3 12.2 4.8

CaO 15.9 12.7 14.2 11.6 7.9

MgO 4.1 3.3 3.6 2.5 1.8

Na2O 10.2 7.8 7.8 4.7 2

K2O 3.9 3.3 3.1 2.2 1.4

SO3 2.2 1.4 1.3 1.1 1.6

P2O5 0.8 0.5 0.6 1.5 4.2

Cl 3.5 3.5 3.4

Total 94.20 94.40 92.20 96.90 98.20CO3 7.6 5.5 6.7 1.48 0.64

*Low temperature ashing at 550 C

The Na and K contents are determined by conventional fuel ash analysis and an in-housechemical analysis. It is noticed that the total Na and K determined by the in-house method isconsiderably higher than the total Na and K determined in ash chemical analyses (Table 4). A

comparison of the alkali contents based on these two analyses is given in Table 5.


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Table 5 Calculation of Na and K in Fuel

7-7-2 7-7-3 7-7-4 7-8-1 Sludge

Based on ash chemical analyses:

Na, % as received 0.188 0.141 0.108 0.174 0.249

K, % as received 0.080 0.067 0.048 0.091 0.195Equivalent Na, % 0.235 0.180 0.137 0.227 0.363

Based on in house analysis

Na, % as received 0.290 0.270 0.272 0.271 0.392

K, % as received 0.101 0.108 0.102 0.091 0.189

Equivalent Na% 0.349 0.334 0.332 0.324 0.503

The difference in Na and K determined is likely caused by the difference in the twolaboratory analytical procedures. Although the low temperature thermal ashing was intended

to prevent release of minerals in vapor form, the temperature of the specimen, when ignited,

may well be above the oven temperature that is controlled at 550 C and therefore, the ash

may have lost some of the alkali compounds. Based on the above hypothetical scenario, itseems logical to conclude that the Na and K values determined by the in-house method are a

better approximation of the total alkali amount in fuel.

Test Sand

As the agglomeration mechanism discussed in the previous section indicates, alkali silicates

may be responsible for agglomeration at relatively low bed temperatures. Hence, pure quartzsand or sand containing with free quartz should be avoided. The bed material used in the tests

is a washed river sand that contains significant levels of Al2O3, Fe2O3, CaO, MgO, as well as

Na2O and K2O.

Ash chemical analysis and in-house chemical analysis of the sand sample indicate that only

small portions of alkalis in the sand are in water-soluble or organically bound form. The restof the alkalis exist in the sand in more chemically stable forms. Based on these detailed

analyses the selected sand was expected to be resistant to forming low melting temperature

compounds. In addition, the fusion temperatures were also determined and are given in Table

6. The data indicates that the initial deformation temperature of the sand is at least 300 Cabove the average bed temperature

Table 6 Ash Fusion Temperatures (C) of Sand Sample

Reducing Oxidizing

Initial Deformation 1187 1251

Soft. Temp. Sph. 1224 1246

Soft. Temp. Hem. 1262 1274

Fluid Temp. 1366 1326


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Operating Conditions

Test 7-7-2 had smooth operation and stable bed temperatures. The average bed temperature

was about 739 C. Due to the short gas residence time in the furnace (5m combustor height

compared to about 30m of a commercial unit), the CO concentration was high. Bed material

at the end of the test showed no signs of sintering.

Test 7-7-3 was shut down prematurely due to fuel feeder jam caused by bed agglomeration.

Upon inspection of the bed drain, many clinkers, up to 50 mm 75mm in size were found.

The highest temperature reached during the test was about 900C at the upper bedtemperature (T3) at the beginning of the test. However, no agglomerates were found in the

first two bed samples (four hours and eight hours into the test). The third sample, taken at the

12th hour, contained several small clinkers up to 25 mm in size (longest dimension).

Test 7-7-4 ran for about 24 hours. There was an interruption caused by a feeder jam that

occurred at about the 7th hour. The combustor had to be emptied to clear the fuel feeder.

After the feeder was fixed, the test resumed with the same bed material. Bed inventorycollected at the end of the test contained a few pieces of agglomerates up to 25 mm in size

(longest dimension).

Test 7-8-1 ran 100 hours continuously as planned, at stable bed temperatures. This test fired a

fuel blend of Powell River hog and sludge at a mass ratio of 10:1. It also had a higher drain

rate aimed at controlling alkali accumulation. No agglomeration was detected from the bedash.

Table 7 summarizes the averaged operating conditions for all four tests.

Table 7 Average Test ConditionsParameter 7-7-2 7-7-3 7-7-4 7-8-1

T2 middle bed, C 739 813 788 776

Oxygen, % dry 7.5 8.0 7.5 8.2

CO2, % dry 12.5 10.7 11.2 9.9

NOx,ppm dry 98 66 79 116

Material Balance

An ash balance summary is given in Table 8. Good ash closures were obtained for the tests.

The unaccounted ash might have been lost in the form of fouling deposit in the combustor as

well as the rest of the unit. Despite the short combustor height, high carbon conversion andcombustion efficiency were achieved.

Sodium and Potassium closures were also calculated. A fraction of both sodium (10-28%)

and potassium (13-20%) was unaccountable. This missing portion of alkali most likely is in

vapor form in the flue gas. Another contributing factor to the unaccountable alkali is thefouling deposits formed in the combustor system. Some of the vapor phase alkalis solidify in

the low temperature area of the back pass. During the tests, the gas sampling probe was


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repeatedly clogged with a white deposit layer, which was determined as mostly NaCl and

KCl.

Table 8 Ash Balance Summary

Parameter 7-7-2 7-7-3 7-7-4 7-8-1

Ash from fuel, kg 5.39 1.19 1.71 13.45Ash from sand, kg 9.87 9.83 9.84 9.84

Total ash in, kg 15.26 11.02 11.55 23.29

Bed ash, kg 9.63 8.15 8.01 9.30

Fly ash, kg 3.83 3.02 2.76 9.08

Total ash out, kg 13.46 11.17 10.77 18.38

Ash out / in, % 88.22 101.35 93.25 78.91

Unaccounted ash, % 11.78 -1.35 6.75 21.09

Alkali Retention in Bed

For all four tests, bed ash samples were taken at four-hour intervals. Typically, every othersample is analyzed for ash composition. The results are plotted in Figures 2, 3, 4 and 5. All

four tests demonstrated a trend of increasing Na and K concentration in the bed ash

By mass balance of all streams of material flow, the alkali retention rates were determined.

The range is 12% to 43%. The alkali retention rate is affected by operating conditions,

especially bed temperatures. The forms of alkali in the fuel, bed material chemistry, and fuelash compositions are the other important contributing factors for the split between vapor

phase and solid phase alkalis. The alkali retention is much less than those obtained with

burning of fuel under similar combustor conditions (e.g. Tuncay et al, 1996). This indicates

that the form of alkali in fuel is very critical in predicting alkali retention.

As shown in Figures 2-5, equilibrium levels of alkali have not been reached at the end of all

four tests. This is because the limited duration of the tests and also the significant bed drainrate due to sampling.

For given combustor operating conditions and feedstock compositions, accumulation ofalkali in the bed can be controlled by draining adequate amount of bed material and

replenishing with fresh sand. Test 7-8-1 was run with a drain rate higher than that of the other

three tests and also with moderate bed temperatures. The test lasted 100 hours with problem-free operation. The bed alkali concentrations were successfully controlled at acceptable

levels. Inspection after the test did not show any signs of agglomeration.

Analyses of Agglomerates

Figure 6 is a 3X magnified photo of a typical agglomerate retrieved from the bed material of

test 7-7-4. This type of agglomerates appears to consist of many small particles of bedmaterial with size in the magnitude of 1mm. Figure 7 is a photo of the same sample taken

with scanning electronic microscope (SEM) at a magnification of 30X. It shows that the


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interstices between particles are filled with molten material that bonds the particles together,

although the individual particles are still distinguishable and have not undergone melting.

Test 7-7-3 had the highest bed temperature of all tests. A typical piece of agglomerate of this

test is shown in Figure 8 in which the piece appears to be fused together to a rounded shape.

Figure 9 is a magnified cross section of agglomerate. In this case, individual particles are nolonger visible. Apparently the bed material had gone through a completely molten or fluid-

like stage. The two types of agglomerates are similar to those described by Lin et al (1997)

from laboratory study of straw burning in a FBC.

Ash chemical analyses were performed on fresh sand, bed ash collected at the end of the test

and fuel ash for Tests 7-7-3 and 7-7-4. In both cases, the chemical compositions of the bedmaterial were still similar to the original sand, but there was also clear enrichment of several

elements such as Na, K and Ca, all of which exist in the fuel. This confirms the alkali

retention and accumulation that was discussed in the previous section.

A comparison of the bed ash and agglomerates can shed some light on the followingquestion: is the agglomerate simply many pieces of bed material stuck together or are there

other factors involved? Ash analyses show that while the agglomerates in both cases havealmost the same alkali contents as in the bed material, there was much more sulfur, calcium

and iron in the agglomerates, elements that are more abundant in fuel ash. This leads to the

following scenario for the formation of the agglomerates. When introduced to the bed, thewood waste first undergoes heat-up and drying. The fuel tends to form clusters within the bed

and on the bed surface. The fibrous structure of wood allows the cluster to hold up many bed

material particles. When a cluster burns at a temperature a few hundred degrees higher thanthe rest of the bed, the bed material that is trapped in the cluster becomes partially molten,

leaving behind a piece of agglomerate when all the combustibles in the wood are burned.

Additional amount of some of the fuel ash constituents such as iron and calcium also get

trapped in the cluster-turned-clinker. The fuel sulfur may be combined with calcium to formcalcium sulfate. Alkali compounds may have been vaporized due to the high temperature.

This may explain the voids / bubbles formed on the photo in Figure 9.

The materials from different stages of the tests were also analyzed with the SEM EDAX

(Energy Dispersive Analytical X-ray). Compared to ash chemical analysis that reports the

bulk properties, EDAX reveals the surface elemental compositions. It was found that on thebed material surface, calcium and magnesium surpassed silica as the most abundant

elements. Evidently the Ca and Mg tend to adhere to the outer surface of bed material

particles.

COMMERCIAL BOILER PERFORMANCE

Based on the laboratory and pilot plant studies, a strategy was developed to address the alkaliaccumulation and agglomeration concern. It includes the following elements: 1) Select a bed

material that resists the formation of low-melting point-compounds. 2) Avoid excessively

high combustor temperatures in the bed and in the freeboard. 3) Achieve stable and uniform


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fluidization and mixing in the bed. 4) Drain and replenish bed material at a sufficient rate to

control alkali accumulation.

Based on the above principles, operating limits/conditions were recommended for the Powell

River #19 BFB boiler. Figure 10 is a schematic of the BFB boiler. The recommendations

have been successfully implemented in the boiler operation. The boiler was first started up inNovember 1997. There has been no significant boiler down time caused by bed

agglomeration. Boiler performance tests were completed in April 1998. All guaranteed

process conditions have been met, with good margin on many parameters. Table 10 is asummary of some boiler performance data.

Table 10 Boiler Performance Summary

Parameter Unit Guarantee Test Avg.

100% MCR Firing Hog Fuel

Steam Flow kg/s 73.7 75.2

Opacity % 10 1.5

NOx mg/Sm3 240 152

CO mg/Sm3 580 129

Main Steam Temp. C 477+/-5 479

SH Outlet Pressure kpa 6516 6576

Gas Temp. Leaving AH C 191 167

Excess Air % 35 33

Carbon in ash % 5


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may be present in vapor form leaving the system. Deposits of solidified alkali chlorides

were seen in the low temperature part of back pass (on gas sampling probe).

4. Analyses of bed material and agglomerate samples showed enrichment of Na, K, Ca, Mgand Fe. Ca and Mg were found in deposits on the outer surface of bed particles. The

formation of agglomerates may involve temperatures significantly higher than the bulkbed temperatures. A hypothetical scenario is proposed where the wood waste fuel may

have formed clusters that carry bed material particles. During combustion and/or

gasification, these clusters generate high temperatures that help partially melt or evencompletely fuse the trapped bed material particles.

Based on the laboratory and pilot plant studies, operation guidelines were developed for thePowell River #19 BFB boiler. Key elements of the strategy for controlling agglomeration at

the BFB boiler are: 1) Select a bed material that resists the formation of low-melting-point

compounds. 2) Avoid excessively high combustor temperatures in the bed and in the

freeboard. 3) Achieve stable and uniform fluidization and mixing in the bed. 4) Drain and

replenish bed material at a sufficient rate to control alkali accumulation.

The recommendations have been successfully implemented in the boiler operation. There hasbeen no significant boiler down time caused by bed agglomeration since the boiler was

started up. Boiler performance tests completed in April 1998 have demonstrated all

guaranteed process conditions.

REFERENCESGrubor, B.D. et al, Biomass FBC Combustion - Bed Agglomeration Problems, Proceedings

of 13th Inter. Conf. on Fluidized Bed Combustion, Vol, Page 515, ASME, 1995

Lin W, et al, Agglomeration Phenomena in Fluidized Bed Combustion of Straw,

Proceedings of 14th Intern. Conf. on Fluidized Bed Combustion, Vol. 2, Page 831,

ASME, 1997Miller, T. R. et al, Alkali Deposits Found in Biomass Power Plants, Summary Report for

National Renewable Energy Laboratory, 1995

Tamhankar, S. S. and Wen C. Y., Review of In-bed Hydrocarbon, Alkali and Trace MetalsControl in Coal Conversion Processes, DOE/MC/14731-1297, 1981

Tuncay, J. et al, Alkali Emission Measurement in Atmospheric Circulating Fluidized Bed

Combustors, Proceedings of 5th Intern. Conf. on Circulating Fluidized Beds, PageGSNA9, 1996

Wall, C.L, J. T. Graves and J. R. Elliot, How to Burn Salty Sludges, Chemical

Engineering, Page 77, April, 1975

Acknowledgement

The authors acknowledge the contribution of Foster Wheeler start-up personnel and

MacMillan Bloedel operating staff in the successful implementation of the pilot test findings

in the commercial unit, and MacMillan Bloedels permission to publish the data.


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2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

0 5 10 15 20 25 30

Test Time, hr

Na2O,%

0

0.5

1

1.5

2

2.5

K2O,%

Na2O K2O Linear (Na2O) Linear (K2O)

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

0.00 10.00 20.00 30.00 40.00 50.00 60.00

Test Time, hr

Na2O,%

0

0.5

1

1.5

2

2.5

K2O,%

Na2O K2O Linear (K2O) Linear (Na2O)

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

0 2 4 6 8 10 12 14

Test Time, hr

Na2O,%

0

0.5

1

1.5

2

2.5

K2O,%

Na2O K2O Linear (K2O) L inear (Na2O)

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

0 20 40 60 80 100 120

Test Time, hr

Na2O,%

0

0.5

1

1.5

2

2.5

K2O,%

Na2 O K 2O L ine ar (K 2O ) Li nea r (Na 2O )

Figure 1 Fluidized bed combustor pilot plant PF-100

Figure 2 Na and K in bed material (Test 7-7-2) Figure 3 Na and K in bed material (Test 7-7-2)

Figure 4 Na and K in bed material (Test 7-7-4) Figure 5 Na and K in bed material (Test 7-8-1)

Primary Air Inlet

T-1

DP1

T-2

T-3

DP2

T-4

T-5

T-6T-8

T-9

DP4

DP3

T-7

P6

ELECTRIC FURNACE

ELECTRIC FURNACE

T-10

T-11

T-12

FLUE GAS TOI.D. FAN / STACK

DP Dust

Collector

Fuel Feeder

Fly Ash

FeedPoint

Fly Ash

CollectionSilos

Analyzer

Probe


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Figure 6 Typical agglomerates from Figure 7 SEM image of an agglomerate

Test 7-7-4 (3X magnification) from Test 7-7-4 (30X magnification)

Figure 8 Typical fused clinker from Figure 9 Cross Section of a clinkerTest 7-7-4 (3X magnification) from Test 7-7-3 (30X magnification)


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Figure 10 Bubbling fluidized bed boiler at Powell River Mill

papermill waste in afbc by fwc

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