DETERMINATION OF SOLIDS RESIDENCE TIME DISTRIBUTION IN CONTINUOUSLY FED, SHALLOW FLUIDIZED BEDS: TOWARDS THE DEVELOPMENT OF A FUEL EFFICIENT CONTAMINATED SOILS INCINERATOR

SOILS CONTAMINATED WITH TOXIC CHEMICALS POSE A THREAT TO THEENVIRONMENT, IN THAT THE CHEMICALS MAY BE SLOWLY RELEASED AND INCORPORATED INTO THE FOOD CHAIN. HIGH TEMPERATURE, THERMAL OXIDATION OFFERS ONE METHOD OF DECONTAMINATING THESESOILS. HOWEVER, BECAUSE OF THE NORMALLY LOW CONCENTRATIONS OF CONTAMINANTS ABSORBED ON SOILS, FUEL IS REQUIRED TO HEAT THE SOIL MASS TO TEMPERATURES NEAR 2,000 F. CURRENT THERMAL TREATMENT PROCESSES ARE INEFFICIENT IN THEIRUSE OF FUEL BECAUSE OF FAILURETO RECOVER HEAT FROM THE DECONTAMINATED SOILS AND FUEL GASES LEAVING THE COMBUSTION ZONE OF THE INCINERATOR. A UNIQUE, THERMALLY EFFICIENT, STAGED, FLUIDIZED BED CONCEPT HAS BEEN DEVELOPED WHICH REDUCES TREATMENT COSTS BY AFFECTING A HIGH DEGREE OF HEAT RECOVERY FROM EFFLUENT STREAMS LEAVING THE COMBUSTION STAGE.THE FOUNDATION OF THE CONCEPT IS BASED UPON TWO ASSUMPTIONS:1. THAT THERMAL EQUILIBRIUM CAN BE ATTAINED BETWEEN CONTACTING CAS AND SOLID STREAMS IN SHALLOW FLUIDIZED BEDS; AND THAT, 2. SOLIDS RESIDENCE TIME DISTRIBUTION IN SHALLOW FLUIDIZED BEDS DO NOT APPROACH WELL-STIRRED BEHAVIOR, AND THUS MAY BE SUITABLE FOR THE ATTAINMENT OF HIGH DESTRUCTION EFFICIENCIES WITHOUT REQUIRING EXTRAORDINARILY LONG RESIDENCE ON THE COMBUSTION STAGE. IN PREVIOUS RESEARCH, ASSUMPTION ONE WAS VERIFIED. THIS PROPOSAL EFFORT IS DESIGNED TO VERIFY THE SECOND ASSUMPTION.ITS SUCCESSFUL CONCLUSION WILL LEAD TO THE CONSTRUCTION AND OPERATION OF A SMALL PILOT UNIT WHICH WILL BE USED TO VERIFYTHE ADVANTAGES OF THE ENTIRE CONCEPT.