Investigations of the Ash Deposit for Coal Blending using Pilot Scale Pulverized Coal Boiler

摘要

Utilization of low-grade coals in Korean power plant is a serious issue in Korean coal power plant. While most of Korean power plants including PC (Pulverized Coal) boiler are designed for bituminous coal (with high heating value and low moisture contents) which were constructed more than 15 years ago. Currently over 50% of coal introduced to those plants are sub-bituminous coals with high moisture contents, lower heating value and lower ash fusion temperature (AFT). In PC boiler, ash depositions such as slagging and fouling may cause of significant effect on the operational life of PC boiler. The purpose of this study is to observe slagging and fouling characteristics using a pilot system with 60kW furnace from burning various ranks of pulverized coals. Five different coal samples - two bituminous coals, three sub-bituminous coals are analyzed in present study. The collected ash from lab. scale furnace and pilot scale furnace were analyzed by X-ray diffraction (XRD). Inductively coupled plasma (ICP) and Ash Fusion Temperature (AFT) measurement also performed in present study to observe the influences on ash deposition in PC boiler. Ash deposit analysis revealed that slagging and fouling factors in sub-bituminous coal combustion ash are higher values than that for bituminous coal combustion in ash experiments.