The report gives results of an engineering evaluation of regeneration of calcium-based SO2 sorbents (limestone and dolomite) for application in both atmospheric and pressurized fluidized-bed combustion (FBC) processes. Economics of FBC power plants, operated with regeneration, are projected based on current estimates of regeneration process performance. Coal-fueled reductive decomposition is the regeneration process considered for atmospheric FBC; three regeneration schemes (two reductive decomposition processes and a two-step process) are evaluated for pressurized FBC. Estimated costs of FBC power plants with regeneration are compared with costs of FBC plants using once-through sorbent (no regeneration). The economic feasibility of the regenerative system depends on several variables, including in particular the sulfur concentration achievable in the regenerator off-gas, the reduction in fresh sorbent feed rate possible through regeneration, and the cost of fresh sorbent and of solid residue disposal. The performance required for the regenerative FBC system to achieve economic feasibility is projected, and critical development needs are discussed. An integrated regeneration system for both atmospheric and pressurized FBC, capable of achieving the performance necessary, has yet to be demonstrated experimentally.

Prepared for U.S. Environmental Protection Agency, Office of Research and Development, under contract no. 68-02-2132, program element no. EHE623A. Issued Mar. 1978. Includes bibliographical references.