CONTROL OF ALKALI METAL COMPOUNDS BY MINERAL PARTICLE INJECTION DURING COAL COMBUSTION

摘要

Alkali metal compounds are contained solid fuel such as coal, wastes and biomass. The vapor of sodium (Na) and potassium (K) compounds affects stable operation of power plants and incinerators, and atmospheric environment. Generally, the vapor of alkali metal compounds is trigger of slugging and fouling. Also it corrodes parts of furnace such as heat exchanger tube and so on. Additionally, fine particulates with size of less than 2.5 μm (PM2.5) emitted from combustion process have been focused as one of the sources of new environmental risk. Therefore alkali metal compounds should be controlled to keep stable operation in the power plants and sustain clean atmospheric environment. In this study, coal combustion tests are conducted using an electrically heated drop tube furnace. Kaolin which is mixed with the coal, is selected as a sorbent to absorb the alkali metal compounds. As a result, Na and K compounds are captured by the kaolin particles and the formation of fine particulates is suppressed. This result suggests that kaolin injection method can apply to control the formation of fine particulates and alkali metal compounds during coal combustion.