Regeneration of Lime for Fluidized-Bed Combustion with Carbon, with Silica, and with Coal Ash

摘要

Two basic processes for regeneration are currently under development. One is based on the reaction between CaSO sub 4 and carbon for the regeneration of CaO. Another is being designed for regeneration and recycling of the calcium silicates as sorbents, with lime and siliceous matters as the starting materials. The two basic processes can be ideally combined in a third system by utilizing the fly ash. Fly ash from the FB combustor contains significant amounts of carbon; about 5-40% from the ANL and the Exxon fluidized bed pilot combustors. By feeding fly ash and sulfated limestone to a kiln-type regenerator, calcium oxide and silicates are formed and are to be recycled to the combustor. Kinetics and other relevant studies such as particle strength for fluidization and chemical analyses of the products for the three processes are being undertaken in parallel. Process and cost analyses are being made. These include material and energy balances and cost analysis with special attention to the regenerative processes being developed. Kinetic models for sulfation and regeneration are being studied. Models for predicting the behavior of FBC from the bench-scale data are being examined. The results of this program to date are summarized. (ERA citation 02:057941)