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THE EVALUATION OF COKES AS FILTER AIDS IN DIRECT COAL LIQUEFACTION.

Objective

THE AIM OF THIS PROJECT IS TO DEVELOP A CARBONACEOUS MATERIAL PRODUCED FROM WITHIN THE DIRECT LIQUEFACTION PROCESS AS A FILTRATION AID.
The aim of this work was to show that filter aids for the filtration of coal liquefaction products can be prepared from feed coal and filtration residues. Recycling of filtration residues can save, at least, part of expensive raw materials. It was found that low temperature fluidised bed carbonisation can be used to produce carbonaceous filter aids for filtration in liquid solvent extraction (LSE) type direct coal liquefaction.
The products were tested in a laboratory filter. The use of these filter aids via a body feed technique resulted in a markedly higher porosity of the filter cake even at higher filtration pressures. The filtration cake is stabilised so that a filtration pressure of 5 bar only 50% of the original filter area is needed.
THE SEPARATION OF INERT SOLIDS ASSOCIATED WITH THE COAL FEED IS AN ESSENTIAL OPERATION WITHIN ALL DIRECT COAL LIQUEFACTION PROCESSING.WHILE HOT PRESSURISED FILTRATION IS AN EFFICIENT METHOD OF SEPARATION THERE WOULD BE TECHNICAL AND ECONOMIC ADVANTAGES IN SUBSTITUTING PROCESS DERIVED CARBONACEOUS FILTER PRECOATS FOR THE MINERAL PRECOATS CURRENTLY USED.THIS COLLABORATIVE PROJECT INVOLVING SEPARATE CONTRACTS WITH BRITISH COAL AND BERGBAU-FORSCHUNG GMBH. WILL TRY TO DEVELOP PRECOATS FOR THE BRITISH AND GERMAN VERSIONS OF THE DIRECT LIQUEFACTION PROCESS.
BRITISH COAL WILL SCREEN IN THE LABORATORY A TOTAL OF 13 CANDIDATE PRECOATS AGAINST TEN EVALUATION CRITERIA.THEY WILL SELECT,IN CONJUNCTION WITH BERGBAU-FORSCHUNG THREE MATERIALS FOR FURTHER DEVELOPMENT.THESE WILL LIKELY INCLUDE A PETROLEUM DERIVED COKE,A COAL EXTRACT DERIVED COKE AND A CARBONISED MATERIAL, EACH HAVING LOW SPECIFIC CAKE RESISTIVITY,GOOD MEDIA BRIDGING AND GOOD MEDIA PROTECTION POTENTIAL.
BRITISH COAL WILL FURTHER EVALUATE THE THREE SELECTED COKES IN A PROPRIETARY VERTICAL LEAF FILTER.THE FILTER SCREENS WILL BE REGULARLY EXAMINED TO ASSESS THE EFFECTIVENESS OF THE PRECOATS.
BERGBAU-FORSCHUNG WILL SELECT THEIR OWN PRECOAT FROM FIVE DIFFERENT SIZE FRACTIONS OF CARBONISED COAL HAVING TESTED THESE FOR COKE RESISTIVITY,FLOW RATE AND EFFECT OF PURIFICATION.THE CHOSEN FRACTION WILL BE USED FOR A HUNDRED CYCLE TEST IN A CANDLE FILTER UNIT.RESULTS WILL BE COMPARED TO PERFORMANCE WITHOUT FILTER AID, PERFORMANCE WITH CARBONISED FILTER CAKE AND TO THE BRITISH COAL FINDINGS.

STATE OF ADVANCEMENT:
THE FIRST PROGRESS REPORT IS EXPECTED IN FEBRUARY 1988.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bergbau-Forschung GmbH
Address
Franz-fischer-weg 61
45307 Essen
Germany