Prediction of Sorbent Performance in a CFB Boiler Based on Sorbent Petrographic Properties

摘要

The required expenditure for purchasing sorbent in the operation of a Circulating Fluidized Bed (CFB) boiler is often a significant item in a plant's operating budget. This requirement is a function of sorbent usage by the boiler and the cost of the sorbent delivered to the boiler. While the latter may be readily estimated, predicting the former is a challenge. The availability of such a means would be of benefit for CFB power plants, which have several available sources of sorbent, the goal being to minimize plant compliance costs. A method for prediction of sorbent consumption is presented here, and has been developed based on plant operating data for a boiler in which several limestone and dolostone products were tested under similar firing conditions. The method considers the characteristic partitioning of calcium and sulfur between the flyash and bottom ash stream for the boiler, the feed particle size distribution of the sorbent, and petrographic properties of the sorbents. The predictions of sorbent usage were compared with plant operating data for five sorbents, of two distinct petrographic types. The plant operating data used featured full load operation. The five sorbents tested were all from Pennsylvania and each contained greater than 40 wt% CaO. In four of the five cases, the predicted sorbent usage was within 10 wt% of the average full load sorbent usage by the boiler.