PRODUCTION OF HOT GAS FOR DRYING PROCESSES USING FLUIDIZED BED COMBUSTION OF COAL

Projektinformationen

ID Finanzhilfevereinbarung: EE-D2-322

Startdatum 1 April 1981

Enddatum 1 Juli 1983

Finanziert unter

• Energy research and development programme (EEC), 1979-1983

Gesamtkosten € 0,00

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Koordiniert durch

CRE GROUP LTD.
United Kingdom

Ziel

PRODUCTION OF HOT GAS FOR DRYING PROCESSES REPRESENTS A SIGNIFICANT USE OF ENERGY IN E.C. COUNTRIES. IN MANY PROCESS INDUSTRIES, THERE IS ALSO A POTENTIAL TO SUBSTITUTE OIL OR GAS BY COAL, IF SUITABLE TECHNOLOGY CAN BE DEVELOPED.

AT PRESENT FLUIDIZED COMBUSTION OF COAL IS BEING SUCCESSFULLY USED TO PRODUCE HOT GAS AT TEMPERATURES UP TO 950 DEGREES C IN APPLICATIONS WHERE SOME PRODUCT CONTAMINATION BY ASH IS ACCEPTABLE. IN ORDER TO EXTEND THE RANGE OF POTENTIAL APPLICATIONS THERE IS A NEED TO DEVELOP THE TECHNOLOGY TO PRODUCE BOTH HOTTER AND CLEANER GASES.

THE NATIONAL COAL BOARD IS EXPERIMENTALLY EVALUATING DESIGN CONCEPTS FOR FLUIDIZED BEDS WHICH ARE ABLE TO PRODUCE A) HOT GAS CONTAINING ASH AT 1250 DEGREES C, B) CLEAN AIR AT 600 DEGREES C AND C) LOW DUST CONTENT GAS AT 700 DEGREES C.

A) IN A TEST INSTALLATION OF 400 KW, THE CONCEPT DESIGN FOR A FLUIDIZED BED PRODUCING FLUE GAS AT 1250 DEGREES C WAS EXPERIMENTALLY TESTED. IT CONSISTED OF TWO ADJACENT FLUIDIZED BEDS, THE FIRST BEING OPERATED AS A PARTIAL GASIFIER PRODUCING LOW CALORIFIC VALUE GAS WHICH IS BURNT IN THE OXYGEN CONTAINING OFF-GAS FROM THE SECOND BED. THE SECOND BED IS FUELED BY THE CHAR FROM THE INCOMPLETE GASIFICATION OF THE FIRST BED AND IS OPERATED WITH A HIGH EXCESS AIR LEVEL AS A CONVENTIONAL FLUID BED. RESULTS FROM THE TESTS SHOW THAT : A COMBUSTIBLE GAS WITH A CALORIFIC VALUE OF 2 TO 4.3 MJ/M3 CAN BE PRODUCED IN THE PYROLISER; THE COMBUSTIBLE GAS WHEN BURNT IN THE OXYGEN RICH GASES FROM THE CHAR COMBUSTOR, CAN PRODUCE HOT GAS AT TEMPERATURES IN EXCESS OF 1250 DEGREES C, WITH AN OXYGEN CONTENT OF 6 %; THE COMBUSTION EFFICIENCY OF THE COMBINED SYSTEM IS BETTER THAN 98 %. SATISFACTORY SCALE-UP WOULD ENABLE COAL FIRED FURNACES TO DIRECTLY REPLACE OIL AND GAS BURNERS FOR DRYERS REQUIRING THESE HIGH TEMPERATURES. SUCH COAL FURNACES WOULD BE SMALLER AND CHEAPER (FOR A GIVEN OUTPUT) THAN THEIR LOWER TEMPERATURE PREDECESSORS AND WOULD OFFER SIGNIFICANT FUEL COST SAVINGS OVER OIL AND GAS FIRING. FOR A 30 MW FURNACE THE ANTICIPATED PAYBACK PERIOD WOULD BE LESS THAN 1 YEAR.

B) THE CONCEPT FOR THE PRODUCTION OF CLEAN AIR AT 600 DEGREES C WAS TESTED IN A 200 KW UNIT. AIR IS HEATED BY PASSING IT THROUGH HEAT EXCHANGER TUBES IN AND ABOVE THE FLUIDIZED BED. THE MULLITE TUBES USED IN THE IN-BED HEAT EXCHANGER BROKE DOWN SEVERAL TIMES. A STUDY SUGGESTED THE USE OF SILICON CARBIDE TUBES WHICH DURING 1000 HRS OF TESTING HAVE PROVED TO BE SATISFACTORY. A FULL SIZE 2.3 MW INSTALLATION FOR A MALTING PLANT HAS BEEN DESIGNED AND CONSTRUCTED. CLEAN HOT AIR WAS PRODUCED DEMONSTRATING BOTH A PROCESS QUALITY BENEFIT AND A SUBSTANTIAL ECONOMIC ADVANTAGE. THE FUEL COST SAVINGS FOR A 5 MW COAL FIRED HEATER OPERATING AT 85 % EFFICIENCY COMPARED TO OIL FIRING WOULD BE UKL 150,000 TO UKL 300,000 PER YEAR, DEPENDING ON THE GRADE OF OIL AND THE NATURE OF THE FIRING PROCESS (DIRECT OR INDIRECT).

Programm/Programme

• PRE-ENNONUC 2C - Energy research and development programme (EEC), 1979-1983

Thema/Themen

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Aufforderung zur Vorschlagseinreichung

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Finanzierungsplan

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Koordinator

CRE GROUP LTD.

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