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OPTIMAL PFBC OPERATING CONDITIONS FOR A MINIMAL POLLUTANT EMISSION, SPECIFICALLY NOX

Objective

IT IS EXPECTED THAT BY CARRYING OUT THE PROPOSED RESEARCH OPERATING AND DESIGN MEASURES CAN BE FOUND WHICH ENABLE MINIMIZING NOX EMISSIONS FROM PFBC COMBUSTORS IN COMBINATION WITH MINIMUM EMISSIONS OF OTHER POLLUTANTS. FROM SUCH KNOWLEDGE NEW AND BETTER EQUIPMENT CAN BE DESIGNED.
PROPOSALS FOR THE DESIGN OF NEW CONSTRUCTION ELEMENTS ESPECIALLY WITH RESPECT TO THE INTERNAL FLUIDMECHANICS OF FLUIDIZED BEDS CAN BE EXPECTED.
The project aimed at minimizing pollutant emission (eg nitrogen oxides (NOx)) but doing this without bringing about a rise in other pollutants (eg, carbon monoxide). Reaction conditions were investigated for minimizing levels of individual pollutants.

Studies of zones were carried out under different conditions in slim tube reactors. In the primary firing zone, nitric oxide was minimized by using a high combustion temperature (900 C) and low oxygen concentration. Nitric oxide did not increase beyond this but carbon monoxide decreased and carbon content increased. For sulphur dioxide binding, there should be a temperature of 850 to 860 C in the secondary and tertiary zones which can be achieved with a suitably placed heat exchanger. After burning of carbon in the splash zone and free area at a temperature above 850 C leads to the reformation of nitric oxide. After burning of carbon monoxide at a higher temperature should solve this problem by abstracting carbon.

It was found that to focus different conditions on each zone required optimization of the reactor pipe geometry as well as the operating pressure and combustion temperature.
IT IS WELL KNOWN THAT PRESSURIZED FLUIDIZED BED COMBUSTION OFFERS THE POTENTIAL OF PARTICULARLY CLEAN AND EFFICIENT USE OF COAL FOR HEAT AND POWER GENERATION. PRESENT ENVIRONMENTAL STANDARDS IN THE FRG, HOWEVER, PARTICULARLY STRINGENT WITH RESPECT TO NOX EMISSIONS WHICH PRESENTLY CANNOT BE COMPLIED WITH IN COMBINATION WITH CO-AND SO2-EMISSION STANDARDS IN STATIONARY ATMOSPHERIC FBC WITHOUT ADDITIONAL FLUE GAS CLEAN UP MEASURES. THE PROJECT WAS PROPOSED IN ORDER TO FIND WAYS OF MINIMISING POLLUTANT EMISSIONS USING THE POTENTIAL OF PRESSURIZED FLUIDIZED BED COMBUSTION (PFBC).IT IS POSSIBLE TO FIND CONDITIONS TO MINIMIZE THE EMISSION OF INDIVIDUAL POLLUTANTS SUCH AS CO, SO2, F, CL AND ALSO NOX. THIS,HOWEVER, TAKES USUALLY PLACE AT THE EXPENSE OF AN INCREASE IN THE EMISSION LEVEL OF ONE OR MORE OF THE OTHERS. IN VIEW OF THE INTERDEPENDENCE OF MEASURES, AN OVERALL OPTIMIZATION OF EMISSION REDUCTION IS REQUIRED, BUT HAS NOT YET BEEN ACHIEVED. PARTICULARLY IN PFBC THE BODY OF EXPERIENCE IS INSUFFICIENT FOR AN OPTIMIZATION OF THE POLLUTANTS REDUCTION. THE PROJECT SERVES TO CONTRIBUTE TO FILL THIS SUBSTANTIAL GAP.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

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

Participants (1)

National Coal Board
United Kingdom