SOxMitigation Technologies for Combustion Systems

Abstract

AbstractSOxemissions from coal‐fired plants cause harmful impacts on the environment and human being health. To limit SOxemissions, air pollution control regulations have been established on international and national levels, and industrially relevant SOxmitigation technologies have been rapidly developed and applied over the past few decades. In this article, fluidized bed combustion (FBC) for in‐furnace DeSOx, dry sorbent injection (DSI), spray drier absorber, circulating dry scrubber (CDS), and wet scrubber processes are comprehensively discussed.The wet scrubber process is the most widespread SO2mitigation technology around the world and is reviewed in detail. The chemistry of wet scrubber processes is analyzed. Four typical wet scrubber configurations are presented. Wet scrubber operational challenges are shortly discussed. The DSI process is comprehensively discussed as well. In this process, fine and dry sorbents are directly injected into flue gas to capture SOxand other acid gases. In the CDS process, flue gas flows upward through a fluidized bed of sorbents to create a long contact time and have good mass transfer conditions. The spray drier process uses an atomizer to generate fine droplets to contact and react with SO2. The regenerable processes are presented, in which sorbents are regenerated. The absorbed SO2is further processed to sealable elemental sulfur or sulfuric acid products. Finally, an outlook of recent and future developments and challenges for SOxmitigation technologies is given.Even though different effective SOxmitigation technologies are available, the economics of their application are dominated by many factors, such as emission limits, fuel quality, sulfur content, size of plant, firing system, availability of sorbents, and utilization of by‐products. Therefore, a case‐by‐case evaluation is recommended to find the most suitable flue gas desulfurization (FGD) process for a particular application.