A pilot scale test on the fluidized melting combustion of coal gasification fine slag

Abstract

To address the issue of coal gasification fine slag (CGFS) disposal, a novel fluidized melting combustion (FMC) process has been proposed. In this study, the operating feasibility, combustion performance and gas pollutant emission were assessed through 0.4 MW pilot-scale test. The results indicated that both temperature and pressure fluctuation remained within the controllable range throughout entire test period. Under the influence of high cycle rate and incomplete combustion, CGFS efficiently achieved the rapid dehydration, preheating and crushing. Some combustible H₂ and CO were generated simultaneously. After the preheating modification, the refractory CGFS transformed into hot gas–solid composite fuel. To achieve the complete carbon removal and ash vitrification, the melting combustion temperature was up to 1501.1 °C. Under the excessively high temperature, liquid slag was discharged smoothly from the tap hole without any observed blockage. Carbon content in slag was only 0.4 wt%. The slag captured rate and decarbonization rate were up to 79.0 % and 93.8 %, respectively. The initial CO emission was as low as 103.0 mg/m³. The initial NO emission reached up to 452.5 mg/m³ under radiation boiler afterburning. Due to the combined influence of multiple factors, the initial SO₂ emission soared up to 1789.3 mg/m³. Further research will focus on controlling flue gas pollutant emissions, resource utilization of molten slag, and developing oxy-combustion. The objective is to attain full carbon neutrality in the entire coal chemical industry process.