Combustion of solid recovered fuels in a semi-industrial circulating fluidized bed pilot plant - Implications of bed material and combustion atmosphere on gaseous emissions

摘要

The application of fluidized bed (FB) systems for the combustion of waste derived fuels, such as solid recovered fuel (SRF), is a well-established method. The moderate combustion temperatures in FB boilers reduce the formation of NO_x while the gaseous emissions of sulfur and chlorine species can be effectively limited by the feed of additives directly into the bed. In contrast to conventional solid fuels such as lignite or hard coal, SRF contains increased quantities of critical fuel constitutes such as chlorine, heavy metals and alkaline metals. Moreover, the composition and quality of the fuel is highly heterogeneous. Thus, it is challenging to characterize the combustion behavior and the formation of gaseous emissions based on the elementary fuel composition. Therefore, experimental investigations are inevitable to assess the combustion of SRF in novel applications. This paper gives an overview of experimental investigations on the combustion of SRF in a semi-industrial circulating fluidized bed (CFB) pilot plant. Two different types of SRF were burnt in oxygen enriched air and oxyfuel atmosphere while using silicate sand and limestone as bed material. These environments are expected to prevail in carbon capture and storage (CCS) processes such as stand-alone CFB oxyfuel combustion, or CFB oxyfuel combustion in the calciner of the calcium looping (CaL) process for post-combustion CO_2 capture.