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INTERNAL CIRCULATING FLUIDIZEDBED TECNOLOGY

FOR CO-FIRING BIOMASS AND COAL

JIANXIONG MAO

DEPARTMENT OF THERMAL ENGINEERING

TSINGHUA UNIVERSITY, BEIJING 100084, CHINA

Sino-German Workshop on

Energetic Utilization of Biomass

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STRUCTURE OF WORLD ENERGY CONSUMPTION IN 2000

2.67.625.024.740.012503.4World

2.5.63.8.00.1

1075.3hina1.3-44.118.036.5151.4Australia

2.512.717.212.055.6179.9Span

13.38,112.630.235.8331.1Canada

0.310.616.738.134.3323.0U.K.

0.613.325.121.739.3470.6Germany

2.35.417.854.619.9887.3Russia

1.09.024.825.839.43235.1U.S.A

Hydro

Power

(%)

Nuclear

(%)

Coal

(%)

Natural

gas

(%)

Oil

(%)

Energy

consumption

(Mtec)

Country

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COMPARISON OF THE STRUCTURE OF COAL CONSUMPTIONBETWEEN CHINA AND SOME DEVELOPED COUNTRIES

---96.6Canada

3.52.514.775.3Australia

5.29.79.875.3UK

0.78.53.887.0USA

6.97.12.530.7hina

Domestic

use

(%)

Industrial

boiler

(%)

Coking and

gasification

(%)Power

(%)

Country

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RATIO OF POLLUTANTS FROM COAL UTILIZATION TO THE

TOTAL POLLUTANTS IN THE AIR (%)

85677090

CO2NOxDustSO2

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RESOUCES OF BIOMASS ENERGY IN CHINA

Total biomass energy resources in China: 473 Mtec

47 % of crop residue 21 % of firewood

20 % of animal dung

12 % of municipal wastes

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CROP RESIDUE IS THE BIGGIST BIOMASS RESOURCES

Main crop residue: residue of rice, corn and wheat,

covering 84.3% of all crop residue in China Total yield of crop residue: 205 Mtec in 1993 and 240

Mtec in 2000

149 Mtec, 62% of crop residue may be available as

fuel for heat and power production

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THE CHARACTERS OF BIOMASS RESOURCES IN CHINA

A renewable and huge natural resource;

Low sulfur

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INTERNAL CIRCULATING FLUIDIZED BED (ICFB) BOILER CO-

FIRING BIOMASS AND COAL

Capacity of ICFB boiler: 35t/h steam

Number of units: 2 in operation (May 2000 andNovember 2001) and 2 under construction stage

User: Zhucheng chemical Engineering Company in

Shandong Province, China

Developed, designed and manufactured by Jiangxi

Jianglian Energy and Environmental EngineeringCorporation

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DESIGN PARAMETERS OF 35T/H ICFB BOILER

82.97Boiler efficiency, %

120Hot air temperature, oC

20Cold air temperature, oC

105Feed water temperature, oC

450Steam temperature, oC

3.82Steam pressure, MPa

35Steam capacity, t/h

DataDesign parameter

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FUEL ANALYSIS (AS AIR DRY BASIS)

0-30-8mm-Particle size

996218622kJ/kgQ ar,net,pLower heatingvalue

37.9938.5%VdafVolatile matter

43.969.00%MarMoisture

4.0732.98%AarAsh

0.660.90%SarSulfur

0.370.87%NarNitrogen

18.344.64%OarOxygen

4.023.06%HarHydrogen

28.5848.55%CarCarbon

Biomass (furfuralresidue produced from

corncob)

Bituminous coal

Data

UnitSymbolName

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DESIGN FEATURES OF ICFB

4 pneumatic boimass

feeders and 2 coal feeders

with hot air

Refractory division baffles in

between coal and biomassbeds

Internal circulating between

coal and biomass beds

4 secondary air ports at 4

corners of the furnace

4 bottom ash drains at coalbed

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SPECIAL FEATURES OF COAL BED

Velocity of coal bed:

2.5 and 4 m/s

Coal bed temperature:

870-920oC

Coal bed is the heat

source of biomass bed

Coal bed provides

biomass bed with coal

ash as bed material

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SPECIAL FEATURES OF LOW VELOCITY BEDS

Bed velocity is 1.6 m/s withbed temperature of 820-870oC

In-bed tube as evaporationheating surface

Protecting the erosion of in-bed tubes

Eliminating elutriation of lightdensity biomass with fluegas

Longer residence time fordrying and burning up ofbiomass

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BOILER PERFORMANCE AT THE FUEL RATIO OFBIOMASS TO COAL OF 8:1 (BY WEIGHT)

9.841.1683.62

Unburned carbon in

fly ash, %

Unburned carbon in

bottom ash, %

Boiler efficiency,

%

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ADVANTAGES OF ICFB FOR CO-FIRING

BIOMASS AND COAL

A combination of both advantages of bubbling bed

and circulation bed: low capital cost, low emissions

and high efficiency.

Suitable for co-firing all different types of biomasswith low heating value and high moisture and coal.

Compact design with long life in-bed tubes.

Outstanding economic and environmental benefits,

the pay back period of capital investment is less than

one year.

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RETROFIT OF COAL FIRED BOILERS TO

CO-FIRING BIOMAS AND COAL

8000 units of coal fired small power plantswith the capacity smaller than 50MW will beclosed down in 5 years in China.

A huge amount of crop residue availablearound these coal fired boiler plants.

A big potential to retrofit these coal firedboilers by using ICFB technology.

Some retrofit projects of 12 -25 MW by usingICFB technology are under consideration.

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CO-FIRING WASTE AND RESIDUE FROM PAPER

MILL, SUGAR MILL, WOOD MILL AND BREWERY

Many industries, such as paper mill, sugar mill, woodmill and brewery using biomass as feedstock, thewaste residue such as sludge, sawdust, bark, furfuralresidue and distillers grain, etc., are low heatingvalue and high moisture content.

Now in China, most of these industries use coal-firedboilers to supply the steam and power to theirprocess with low efficiency and high pollution.

There is a big potential to spread and utilize ICFBboilers to co-firing biomass and coal for theseindustries. A 65t/h ICFB project in a paper mill isunder evaluation stage.

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POTENTIAL OF RICE HUSK CO-FIRING CHP

PLANTS FOR RICE GRANARY

Annual production of rice husk is 40 million tons. Ricehusk has been concentrated and is easy to handle.

A rice granary with capacity of 100t/day of rice husk

can feed a 10 MW CHP plant. If 60% of rice husk can be converted into energy,

2400 MW CHP plants can be built.

A big potential of rice husk co-firing CHP plants byusing ICFB technology.

A rice husk co-firing CHP plant is under evaluationstage.

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CONCLUSIONS

Chinas energy consumption structure must bereformed to use more clean energy, includingbiomass.

ICBF is specially designed for co-firing biomass and

coal with outstanding advantages. There is a big potential in China to use ICFB

technology to retrofit coal fired boilers into co-firingbiomass and coal.

To extensively spread ICFB technology for co-firingbiomass and coal, we need:

- Further demonstration with various biomass.

- Aggressive tax incentives and policy forgreen

energy.

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THANK YOU