Babcock & Wilcox 1

F. BelinM. Maryamchik

D.J. WalkerD.L. Wietzke

The Babcock & Wilcox CompanyBarberton, Ohio, U.S.A.

Presented to:16th International Conference on FBCMay 13-16, 2001Reno, Nevada, U.S.A.

Babcock & Wilcox CFB Boilers—Design and Experience

BR-1711

AbstractThe distinctive feature of Babcock & Wilcox (B&W) CFB

boilers is a two-stage solids separation system consisting of theimpact-type primary solids separator (U-beams) and the sec-ondary multi-cyclone dust collector. Lessons learned from 15years of B&W’s CFB technology application have been used todevelop a reliable, low cost boiler design. Advantages of boil-ers with a two-stage solids separation system are described. Op-eration of B&W coal-fired CFB boilers over the last 10 yearshas demonstrated high reliability of the two-stage solids sepa-rator. Superior solids collection efficiency of the two-stage sepa-rator provides higher furnace heat-transfer rate, ability to bettercontrol furnace temperature, and increased residence time offine carbon and sorbent particles. As a result, the required boilerperformance is achieved with lower furnace height and smallerboiler footprint. The current B&W IR-CFB boiler design is de-scribed. Compactness of the IR-CFB makes it especially attrac-tive for PC boiler retrofit applications. Considerations for IR-CFB scale-up are provided.

BackgroundThe major distinction between circulating fluidized-bed

(CFB) boilers competing in today’s market is in the type of thesolids separator. CFB boilers with large cyclone separators con-nected to the furnace outlet (hot-cyclone type) were introducedin mid-1970s and are being offered by several boiler manufac-turers. CFB boilers with impact separators, offered byBabcock&Wilcox (B&W) and its licencees, entered the marketmore than ten years later and since then have been gaining wideacceptance.

B&W CFB boilers feature a two-stage solids separator. Theprimary stage is an impact solids separator located at the fur-nace exit collecting the bulk of the solids (95-97%) that are thenreturned to the furnace by gravity. The primary separator is ar-ranged as an array (Figure 1) of U-shaped vertical elements (U-beams). The secondary separation stage, typically a multi-cy-clone dust collector (MDC), is located in the lower gas tem-perature region of the boiler convection pass, i.e., 480 F to950 F (250 C to 510 C). In some cases the first fields of anelectrostatic precipitator are used as the secondary separator.The fine particles collected by the secondary separator are re-turned to the furnace via a pneumatic (in earlier designs) or grav-ity transport system.

The U-beam separator has evolved through three B&W CFBboiler design generations:

• First generation (first started-up in1986) - All U-beams(11 rows) installed external to the furnace with solids re-cycle through non-mechanical controllable L-valves.(1)

• Second generation (first started-up in 1989) - Two rowsof in-furnace U-beams discharging collected particles(about 70 % of incoming solids) directly to the furnaceand seven rows of external U-beams with solids recyclethrough L-valves.(2)

• Third generation (first started-up in 1996) - Two rows ofin-furnace U-beams and three or four rows of externalU-beams with all solids internally recycled within thefurnace (currently offered “IR- CFB”separator shown inFigure 2).(3)

As a result, dramatic simplification and cost reduction ofthe U-beam separator have been achieved.

2 Babcock & Wilcox

Over the same period, the design of the MDC separator hasbeen improved for better efficiency, reliability and maintain-ability. The current design (Figure 3) has a top gas inlet and aside gas outlet. The cyclone elements have 9 in. (229 mm) di-ameter regardless of boiler capacity. The cyclone sleeves andspin vanes are made of high hardness (550 BHN) material. TheMDC solids recycle system has evolved from dense-phase pneu-matic transport (first generation) to dilute-phase pneumatictransport (second generation) to gravity conveying (third gen-eration).

The second-generation CFB boiler at Ebensburg, Pennsyl-vania, in a cogeneration plant commissioned in early 1991, ex-emplifies the long-term boiler performance. This boiler (Figure4) burns high-ash (average 45% ash) Western Pennylvania wastebituminous coal. The unit was designed for 55 MWe capacity(211 tph steam flow), but was uprated in 1995 and again in1997 and since has been operated at 10% overload. Boiler per-formance and availability are shown in Table 1 and Figure 5respectively. The Ebensburg plant received the Association ofIndependent Power Producers of Pennsylvania (ARIPPA) awardfor the highest availability among plants firing coal mine wastefuels.

The CFB boiler at Southern Illinois University (SIU) inCarbondale, Illinois, represents the third generation design. Theboiler (Figure 6) was designed for 35 MWt output for cogen-eration application, utilizing high-sulfur Illinois bituminous coal.Boiler performance and availability are shown in Table 2 andFigure 7, respectively. The third generation design was also usedfor the Kanoria Chemical project in India and is the design ba-

sis for all new offerings including the most recent contract for a90 MWe IR-CFB in Tychy, Poland.

Operating experience of B&W coal-fired CFB boilers hasclearly confirmed their efficient performance and high reliability.

Design FeaturesThe design of a solids separator is the core of a CFB com-

bustion technology since it has major impact on the boiler lay-out, cost, fuel and sorbent utilization, operational flexibility andreliability. In all these aspects B&W’s CFB boilers with the two-stage solids separation provide the following design features:

a) High solids collection efficiencyThe collection efficiency of the two-stage solids separator is

intrinsically high due to the greater efficiency of the MDC in-ternal collection elements. Higher solids collection efficiencyhelps to achieve greater inventory of fine circulating particlesin the furnace that provides: a) higher furnace heat transfer rate,b) ability to better control furnace temperature, and c) bettercarbon and sorbent utilization due to the increased residencetime of fine particles.

Fig. 1 U-beam primary separators—plan view.

1. Sidewall Membrane Panel2. U-Beam3. Seal Baffle

Furnace Roof

Furnace

In -FurnaceU-Beams

External U-Beams

Solids Transfer Hopper

SolidsTransferHopper

Gas Flow

ExternalU-Beams

In -FurnaceU-Beams

Fig. 2 IR-CFB primary particle collection system.

Fig. 3 Multicyclone dust collector.

Fig. 4 Ebensburg CFB boiler.

Babcock & Wilcox 3

b) Controlled furnace temperatureThe furnace temperature is controlled in response to load

changes and variations of fuel and/or sorbent properties by con-trolling the solids recycle rate from the MDC. The recycle rateat high boiler loads is set to achieve the upper furnace densityrequired to maintain the target furnace temperature. At low loads,the recycle rate directly controls the dense bed temperature. Thecapacity of the MDC hoppers is used for solids transfer to andfrom the furnace. Excessive solids collected by the MDC arepurged if needed. With B&W CFB boilers the load can be re-duced without auxiliary fuel to 20% MCR.

c) Low auxiliary powerThe auxiliary power requirement is lower for impact-sepa-

rator type boilers since the total pressure drop across the two-stage separator (U-beams + MDC) is only 4 in. wc (1 kPa). Inaddition, high-pressure air blowers for fluidization of returningsolids are not needed.

d) Uniform gas flowThe gases exiting from the furnace to the U-beam separator

across the furnace width provide for a uniform two-dimensional

Table 1Ebensburg Operating Data

Operating Steam Flow, t/hr (klb/hr) 234 (516)

Steam Flow @ MCR, t/hr (klb/hr) 211 (465)

Steam Temperature, C (F) 512 (953)

Steam Pressure, MPa (psig) 10.6 (1540)

SH Steam Temperature Control Range, % 30-110

Load Turndown Ratio Without Auxiliary Fuel 5:1

EmissionsNOx, ppm (lb/106 Btu) <100 (<0.14)SO2, ppm (lb/106 Btu) <300 (<0.60)CO, ppm (lb/106 Btu) <230 (<0.20)

Ca/S Molar Ratio 2.1-2.4

100

95

90

85

80

0

Forced Outage Planned Outage Boiler Availability

1991 1992 1993 1994 1995 1996 1997 1998 1999(May-Dec.) (Jan.-July)

1.9

8.4

89.7

1.2

9.4

89.4

3.9

4.5

91.6

5.3

5.6

89.1

2.6

6.6

90.8

2.2

2.8

95.0

1.4

5.6

93.0

1.8

4.2

94.0

1.5

2.9

95.6

1.8

3.4

94.8

0.71.3

98.0

2000(Jan.-June)

Bo

ile

r A

va

ila

bil

ity,

Pe

rce

nt

Fig. 5 Ebensburg boiler availability.

Fig. 6 Southern Illinois University IR-CFB boiler.

gas flow pattern. This allows placement of in-furnace surfacesas needed over the entire furnace height and width, includingthe region adjacent to the rear wall in the upper furnace. Withproven reliability of in-furnace heating surfaces, this makesunnecessary the use of external heat exchangers and allows se-lection of the furnace height based on combustion/sulfur cap-ture considerations rather than heating surface requirements.Combined with high collection efficiency of the two-stage sol-ids separator, this allows reduced furnace height.

4 Babcock & Wilcox

e) High solids separator reliabilityU-beams and MDC have high reliability and low mainte-

nance since they do not include any maintenance-intensive com-ponents such as refractory, loop-seals, expansion joints, vortexfinders, etc. The U-beam design that has evolved through 15years of operating experience has proven to be very reliable,requiring no maintenance. U-beam design criteria includes con-servative assumptions of 25 year life of U-beam materials andsupports. The MDC internals require some maintenance duringplanned shutdowns; this expense has been minimal on the oper-ating B&W CFBs.

f) Integral design/small footprintThe U-beam separator is integral with the boiler enclosure

providing for the most compact and cost-efficient boiler layoutsimilar to the conventional two-pass pulverized coal (PC) boiler.This feature is especially important for retrofitting outdated PCboilers with CFB technology in repowering applications wherekeeping the existing boiler “footprint” is highly desirable.

g) Minimal refractory useThe amount of refractory used in the B&W CFB boilers is

80-90% less than that used for similar capacity CFB boilers withnon-cooled hot cyclones and 40-50% less than CFB boilers withcooled cyclones. For B&W CFB boilers the start-up time is notlimited by rate of temperature rise of the refractory.

Two key areas important for design evaluation of CFB boil-ers with impact separators are high reliability of the two-stagesolids separator and its superior collection efficiency. The long-term operating experience and test data provide the definite af-firmation of the impact separator plus MDC design as describedin the following section.

Two-stage solids separator experience

ReliabilityU-beam experience. U-beams are conservatively designed

to operate in the flue gas environment at the exit of the CFBfurnace. B&W has selected U-beam materials–typically highnickel, high chromium, austenitic stainless steels–to resist ero-sion and corrosion while possessing adequate long-term strengthat the design temperatures. Substantial design margins are pro-

vided to accommodate possible U-beam temperature deviationsfrom the expected value based on average gas temperature leav-ing the furnace. These margins eliminate the possibility of theU-beams being damaged during operational upsets.

Mechanical conditions of U-beams along with related boilerthermal performance data have been monitored over the 10 yearsof operation at the Ebensburg CFB boiler. B&W confirmed thaterosion losses were negligible due to a tough, erosion-resistantfilm formed on the surface of the U-beams. B&W also deter-mined that the material was resistant to corrosion and deforma-tion when operated within the design margins.

The Ebensburg CFB boiler capacity was increased by 10%over original design. For evaluated economic reasons no otherchanges to the boiler were made to maintain the design tem-perature and excess air at the furnace exit. This resulted in morethan three years of operation with local U-beam temperaturesapproaching or exceeding the design margins.

After this three year period of operation with excessivelyhigh temperatures, signs of U-beam mechanical degradationbegan appearing where the maximum temperatures or maximumsolids loading occur. Some U-beam channels began to flare, andthe mid-sections of several U-beams rotated up to 10 degreesfrom the original position. Also, several corrosion spots werefound near the bottom of the rear-most rows of U-beams whereU-beams were covered with ash deposits. The current designhas been changed to avoid these degradations even during pro-longed high-temperature operation.

Regardless of some U-beam deformation observed as a re-sult of the off-design operating conditions, no deterioration ofboiler performance was detected and no U-beams have had tobe replaced. Maintenance work on U-beams has been minimal,consisting primarily of cleaning solids accumulated on the topside of the alignment pans located near the bottom of U-beams,and an occasional repair of the pan and strap attachment welds.

The resilience of U-beams to operating conditions associ-ated with excessive temperatures and increased gas velocitiescontrasts to that of vortex finders (a part of hot-cyclones) whichare made of similar materials and exposed to a similar gas/sol-ids environment.

Vortex finder failures have been reported with a substantialdetrimental effect on boiler performance and considerable main-tenance costs.

Table 2SIU Operating Data

Steam Flow @ MCR, t/hr (klb/hr) 46 (101.5)

Steam Temperature, C (F) 399 (750)

Steam Pressure, MPa (psig) 4.4 (640)

SH Steam Temperature Control Range, % 40-100

Load Turndown Ratio Without Auxiliary Fuel 5:1

EmissionsNOx, ppm (lb/106 Btu) <100 (<0.14)SO2, % removal 90CO, ppm (lb/106 Btu) <200 (<0.17)

Ca/S Molar Ratio 2.3

100

95

90

85

80

85

11.0

89.0

10.3

89.7

1.4

10.7

87.9

4.9

95.1

1997 1998 1999 2000(Jul 15-Dec 31) (Jan-Jun)

Forced Outage

Commissioning Outage

Planned Outage

Boiler Available

Boi

ler A

vaila

bilit

y, %

Fig. 7 SIU boiler availability.

Babcock & Wilcox 5

MDC experienceAt Ebensburg, due to the waste coal’s high ash content and

ash abrasiveness, about 20% of the MDC internal elements arebeing replaced during each yearly outage to avoid a loss of MDCefficiency. At other B&W CFB boilers burning high-sulfur bi-tuminous coal, circulating solids are typically less abrasive ascompared to the Ebensburg unit, and the MDC internal elementshave either not required replacement or have been replaced asneeded during planned outages. At Southern Illinois University(SIU) firing medium-ash high-sulfur coal, practically no ero-sion of the internal elements has been detected since the start-up four years ago.

Maintenance work was needed on the Ebensburg pneumaticMDC solids recycle system which normally is done on line, orduring planned boiler outages. At SIU, where air-slide ash con-veyors were used, virtually no maintenance work was neededon the return system during four years of boiler operation. Thissystem has been further simplified for new offerings. The sim-plicity and low maintenance features of the current MDC solidsreturn system design are discussed below (see “Design improve-ments”).

Maintenance costThe maintenance cost of the solids separators in the B&W

CFB boilers is intrinsically low. At Ebensburg, the total main-tenance cost for U-beams and L-valves over 10 years of opera-tion was about US$20,000. The average maintenance cost forthe MDC was about $25,000 per year. There was no loss of powergeneration due to U-beam or L-valve related problems and onlya negligible loss of generation due to the load reduction duringMDC recycle system problems and its on-line repairs.

Design improvementsA number of design improvements to the two-stage solids

separation system have been implemented based on experienceand design developments:

- Laboratory testing and boiler operating experience haveshown that with proper design parameters, fewer rows of U-beams provide equal collection efficiency. The number of rowsof U-beams has been reduced to eliminate inactive rows therebyreducing the space occupied by the separator as well as reduc-ing pressure differential across the separator and the correspond-ing auxiliary power requirement.

- The alignment pan at the bottom of each U-beam has beenreconfigured to form an open funnel which reduces solids accu-mulation. Together with the reduced number of U-beam rows,this reduces solids accumulation at the bottom of the U-beamsand the possibility of corrosion in this zone.

- Variations such as fuel properties and limestone sizing and/or type, as well as other operational upsets, may cause prolongedgas temperature increase over the design temperature in the U-beam zone. Also, U-beams lack protection from metal tempera-ture excursions similar to those available for the superheatermetal (such as attemperators). Thus, wide design margins areprovided for the U-beams by specifying high quality materialsfor these off-normal conditions. U-beam materials and construc-tions with an oxidation temperature limit as high as 2100 F(1150 C) are used.

- Locating the MDC upstream of the economizer, and therebyat higher elevation in the convection downpass, allows recy-cling of the MDC solids to the lower furnace using a slopinggravity return line(s) with a small quantity of assist air taken

from the forced draft fan. Material velocity in the sloping re-turn lines is low, resulting in low erosion potential. This designsimplifies the recycle system, improves its reliability, and re-duces power consumption.

- Variable speed, inclined screw(s) are used at the MDChopper discharge(s), in place of previously used rotary valves,to control the flow rate of recycled solids. The solids in theinclined screw provide the required pressure seal without themaintenance associated with the close-tolerance, machined sur-faces found in rotary valves.

Solids Collection EfficiencyThe only meaningful measure of CFB solids separation sys-

tem performance is the fractional solids collection efficiency.The overall collection efficiency depends on the size distribu-tion of solids entering the separator and is not indicative of aseparator’s ability to retain fine particles, most important forCFB boiler performance.

The fractional collection efficiency of the two-stage solidsseparation system used in B&W CFB boilers is determined bythe efficiency of the second stage separator. The fractional col-lection efficiency of the secondary separator (MDC) of B&W’sIR-CFB boiler at SIU is shown in Figure 8. The fractional col-lection efficiency of the secondary separator was readily mea-surable during the tests of B&W CFB boilers. Samples of sol-ids passing and collected by the separator were analyzed for theparticle size distribution. The flow rate of collected solids wasdetermined by calibration of the recycle system feeder. The flowrate of passing solids (fly ash) was determined as the differencebetween solids entering the boiler and the bed drain flow rate.The latter was determined from the heat balance of the screwcooler.

A comparison of fly ash particle size distribution based onpublished data for hot-cyclone CFB boilers(4,5,6,7) and measure-ments taken at B&W’s CFB boiler at SIU is shown in Figure 9.One can see that the upper cut size of solids separation at 98%of passing solids is about 80 micron for the SIU IR-CFB. Thisresults in a high percentage of fine ash being recycled to thefurnace, thus giving a high rate of heat transfer in the upperfurnace as well as a high rate of calcium and carbon recycle.

Current IR-CFB DesignThe following on-going projects illustrate the use of the IR-

CFB boiler in two different types of applications. The first one(Tychy) represents an application where there is no space re-straint for B&W’s IR-CFB boiler layout. The others (Nesvetayand Cherepet) are projects where the CFB boiler fits into thesame structure as the existing PC unit.(8)

Tychy Power Plant (Poland)This boiler (Figure 10) will produce 700,000 lb/hr (317 t/hr)

steam at 1740 psi/1004F (120 bar/540C). The fuel is a high-ashbituminous coal with a possibility of co-firing biofuels (up to5% by heat input).

The following unit description for the Tychy project is alsoa description of a “typical” IR-CFB design.

The furnace and horizontal convection pass enclosure aretop-supported and made of gas-tight membrane walls. The fur-nace contains four water-cooled division walls, plus two water-cooled and six steam-cooled wing walls.

6 Babcock & Wilcox

Fuel is fed to the lower furnace through the front wall usingfour air-assisted chutes. Limestone is injected pneumaticallythrough multiple points uniformly across the width of the fur-nace near the bottom. Start-up fuel (light oil) is fired using fiveburners mounted at the rear wall.

Separate fans supply primary and secondary air. Primary airis introduced through the bubble cap grid at the furnace floorwith secondary air introduced uniformly across the furnace widthusing nozzles at the front and rear walls sized to provide airdistribution across the furnace.

The lower furnace is protected from erosion and corrosiveconditions by a layer of low-cement, high-strength refractory.This material has proven to require little maintenance in thelower CFB furnace environment. The membrane tubes at theupper edge of the refractory in the lower furnace are protectedfrom erosion by the patented Reduced Diameter Zone (RDZ)(Figure 11). The RDZ consists of a reduced diameter tube sec-tion mating to a specially shaped ceramic tile. The reduced di-ameter tube section on each tube slopes away from the solids

falling down the wall along the surface profile of the tube panel,thereby eliminating the discontinuity adjacent to the tube. TheRDZ feature is applicable for enclosure walls and internal walls,and has been proven effective in B&W CFB boiler commercialoperation.

The U-beam separator consists of two rows of in-furnaceand three rows of external U-beams. Pendant superheater banksare located downstream of the U-beams in the horizontal con-vection pass. Steam from the drum flows through the side wallsof the pendant superheater enclosure, then through the primarysuperheater bank followed by the wing walls and the secondarysuperheater bank to the main steam outlet.

The MDC is located immediately downstream of the hori-zontal convection pass. Further in the gas path it is followed by

20 40 60 80 100

100

90

80

70

60

Particle Size, micron

Col

lect

ion

Effi

cien

cy, %

Fig. 8 Fractional collection efficiency of MDC (IR-CFB at SIU).

100

80

60

40

20

1 5 10 50 100 200 300

Per

cent

Pas

sing

Particle Size, Micron

Hot Cyclone (Ref. 4)

Hot Cyclone (Ref. 5)

Hot Cyclone (Ref. 6)

Hot Cyclone (Ref. 7)

Two-Stage Solids Separation (B&W-SIU)

Fig. 9 Particle size distribution of fly ash for hot cyclones andtwo-stage separation system.

Fig. 10 Tychy IR-CFB boiler.

Fig. 11 Reduced Diameter Zone.

Furnace Wall(inside)

Division Wall

Babcock & Wilcox 7

the economizer and tubular air heater (air inside tubes). The airheater is side-split for the primary and secondary air. After theair heater, gas flows through an electrostatic precipitator andtwo parallel ID fans to a stack.

Solids collected by the MDC are recycled back to the fur-nace through six recycle lines utilizing inclined screw convey-ors and gravity feed.

Nesvetay Power Plant (Russia)This project emphasizes the compactness of B&W’s IR-CFB

design providing unique benefits in retrofit applications.This 50 MWe PC-boiler firing anthracite culm with up to

40% ash content at the Nesvetay power plant in Russia will bereplaced with the same capacity CFB unit supplied byBelenergomash of Belgorod, Russia, a licensee of B&W CFBtechnology. The plant space constraints require the CFB unit tofit within the plan area of the bay occupied by the PC boiler.This determines furnace plan area and thus furnace gas veloc-ity. Furnace height is then determined by the gas residence timerequired for burnout of the very low-reactive fuel (4-5% vola-

tile matter content). Based on test results for a similar fuel inthe 2.5 MWt CFB pilot unit at B&W’s Alliance Research Center,the furnace height was increased about 30 ft (9 m) as compared tothe PC boiler to attain the guaranteed combustion efficiency of97%. High combustion efficiency is achieved by utilizing effec-tive collection and recycle of fine solids from the MDC.

Figure 12 shows how the new unit fits within the existingbay when the only required modification to the building is aheight increase. The fore-to-aft footprint of this unit as com-pared to the Tychy unit is reduced by two means: a) placingpart of the superheater in the vertical downpass, thus reducingthe depth of the horizontal pass, and b) utilizing available spacefor the air heater at the side of the downpass.

Cherepet Power Plant (Russia)The Cherepet plant (located at Tula region, 200 km south

from Moscow) has a total of eight PC-fired boilers, represent-ing four 150 MWe units (two boilers per turbine), consideredfor CFB repowering. Those boilers of 250 t/hr capacity featurehigh steam parameters (2465 psia, 1013 F) and reheat. Two major

CFB Boiler PC Boiler (TP-230 type)

Fig. 12 Size comparison of PC boiler firing anthracite culm and its repowering CFB boiler.

7600 3600 6400 8590 3360 3700

8 Babcock & Wilcox

fuels to be fired are local high-ash, high-sulfur lignite and low-reactive, medium-ash bituminous coal. CFB boilers ofBelenergomash design will fit into the existing PC-boiler steel(Figure 13).

IR-CFB scale-up. Since scaling-up the two-stage solidsseparator does not present a problem, the only issue of design-ing larger capacity IR-CFB boilers is providing an acceptablefurnace aspect ratio and acceptable gas velocity in the U-beams.With the current design approach, IR-CFB boilers with the de-sign similar to that described above are offered for capacitiesup to 180 MWe (540 MWt).

Fig. 13 Size comparison of PC boiler firing lignite and bituminous coal and its repowering CFB boiler.

CFB Boiler PC Boiler (TP-240 type)

ConclusionLessons learned from 15 years of B&W’s CFB technology

application have led to development of the reliable, low-costIR-CFB boiler design. Long-term operating experience of thedistinct two-stage solids separator has proven its high reliabil-ity and superior collection efficiency. The main advantages ofthis boiler design are higher furnace heat transfer rate, abilityto better control furnace temperature, and increased residencetime of fine carbon and sorbent particles. The IR-CFB boilerachieves the required performance with lower furnace heightand smaller boiler footprint. This design is especially attrac-tive for replacing existing obsolete PC boilers in the same space.

Babcock & Wilcox 9

Copyright © 2001 by The Babcock & Wilcox Company,All rights reserved.

No part of this work may be published, translated or reproduced in any form or by any means, or incorporated into any information retrieval system,without the written permission of the copyright holder. Permission requests should be addressed to: Market Communications, The Babcock &Wilcox Company, P.O. Box 351, Barberton, Ohio, U.S.A. 44203-0351.

Disclaimer

Although the information presented in this work is believed to be reliable, this work is published with the understanding that The Babcock & WilcoxCompany and the authors are supplying general information and are not attempting to render or provide engineering or professional services.Neither The Babcock & Wilcox Company nor any of its employees make any warranty, guarantee, or representation, whether expressed or implied,with respect to the accuracy, completeness or usefulness of any information, product, process or apparatus discussed in this work; and neither TheBabcock & Wilcox Company nor any of its employees shall be liable for any losses or damages with respect to or resulting from the use of, or theinability to use, any information, product, process or apparatus discussed in this work.

1. F. Belin, et al., “Waste Wood Combustion in CirculatingFluidized Bed Boilers,” Proceedings of the Second InternationalConference on Circulating Fluidized Beds, 1988.

2. C. E. Price and D. J. Walker, “Coal and Waste Coal-FiredBoilers Accumulate Operating Experience,” Proceedings of 12th

International Conference on Fluidized-Bed Combustion, 1993.3. F. Belin, et al. , “Update of Operating Experience of B&W

IR-CFB Coal-Fired Boilers,” Proceedings of 15th InternationalConference on Fluidized-Bed Combustion, 1999.

4. D. R. Hajicek et al. , “The Impact of Coal Quality onCirculating Fluidized Bed Combustor Performance,” EPRI CoalQuality Conference, 1992.

5. W. vom Berg and K.-H. Puch, “Verwertung vonRuckstanden aus Wirbelschichtfeuerungsanlagen,” VortrageVGB – Konferenz, “Wirbelschihtsysteme 1992”.

6. M. Gierse, “Aspects of the Performance of Three Differ-ent Types of Industrial Fluidized Bed Boilers,” Proceedings ofthe 3rd International Conference on Circulating Fluidized Beds,1990.

7. U. Muschelknautz and E. Muschelknautz, “Improvementsof Cyclones In CFB Power Plants and Quantitative Estimationon Their Effects on the Boiler Solids Inventory,” Proceedingsof the 6th International Conference on Circulating FluidizedBeds, 1999.

8. D.A. Shaposhnik and S.V. Berdin, “Issues of CFB BoilersDesign for Power Plant Retrofits,” VTI Science and Technol-ogy Seminar, 2001.

References