Combustion Property Improvement of Poorly Combustible Coal by Co-Firing of Agglomerates Consisting of Biomass-Calcium Carbonate and Coals (II): Co-Firing Characteristics in Pulverized Poorly Combustible Coal Combustions

In order to improve combustion property of poorly combustible coals, Coal Combustion Improver (CCI) has been developed by pressured agglomerations at composition ratio (dry basis) of 1 (coal): 1 (synthetic calcium carbonate and biomass from Lime Cake (LC) from sugar production or Paper Sludge (PS) from paper production. CCI's co-firing characterization was studied at composition ratio of 100 (poorly combustible coals): 10 (CCI) under a bench-scaled pulverized coal combustion furnace (1,450 degrees C). In this coal -CCI mixture (particle size : 75 mu: 80% passage) CCI was previously split into biomass, coal, lime, coal particles, and their composite particles, and dispersed uniformly throughout coal fines during co-pulverizing process. Thereby, combustion, air pollutant emission characteristics and fly ash properties of poorly combustible coals were improved. The behavior of eluting heavy metals in ashes was related closely to its volatility and cohesiveness in co-firing. The elution of arsenic, selenium and boron was reduced by reaction with CaO in CCI, and the elution of volatile non-agglutinative fluorine was immobilized and greatly decreased, whereas the elution of non-volatile hexavalent chromium was increased by oxidation.