DESULFURIZATION OF FUELS WITH CALCIUM-BASED SORBENTS

Calcium-based sorbents, such as limestone and dolomite, are viable candidates for sulphur-capturing agents in an in-situ coal gasification/desulfurization process. The effect of limestone addition on the hydrodynamics of a fluidized-bed gasifier, desulfurization of the product gas, and stabilization of the solid wastes have been studied. The hydrodynamic characteristics of coal char/limestone mixtures, such as mixing and fines retention, have been studied in a 0.2-m diameter fluidization column. Kinetic data pertaining to the reaction between calcium oxide (which is obtained by calcination of limestone and dolomite) and hydrogen sulfide have been obtained by a gravimetric technique in the temperature range of 650 to 1050°C. Kinetic data relating to the reaction between calcium sulfide (which is obtained by sulfidation of calcium-based sorbents) and oxygen have been obtained in the temperature range of 800 to 1050°C and in the pressure range of 2 to 3.1 MPa. The operating conditions for these reactions have been chosen to be within the application range of a commercial coal gasification process that is accompanied by in situ desulfurization. © 1990.