Suspension co-combustion tests of pressurized gasification ash and bituminous coal in an MW-scale facility: effects of ultra-low volatile pressurized gasification ash blending ratio

Pressurized gasification plays a significant role in clean coal technology, but the by-product, coal gasification fine ash (CGFA), exhibits a year-on-year increase in emission volumes, which severely constrains the healthy development of the coal gasification industry. In this study, CGFA with ultra-low calorific value and ultra-low volatile content was utilized as a substitute fuel for coal and was consumed via chamber combustion. By constructing a MW-scale swirl combustion system, the combustion characteristics of pressurized coal gasification fine ash (calorific value: 8660.01 kJ/kg, volatile matter content: 3.52%) blended with bituminous coal at different blending ratios (pressurized CGFA blending ratio: 0–40%) were investigated. Comprehensive measurements were conducted on in-furnace parameters such as temperature, flue gas composition, and fly ash burnout rate. Stable ignition and efficient burnout of pressurized CGFA were achieved. At a 30% blending ratio, the furnace flame remained bright and stable, with the maximum temperature in the main combustion zone exceeding 1300 ℃. The burnout rate reached as high as 99.24%, while NO _x emissions at the furnace outlet were measured at 290.93 mg/m³, a 32.19% decrease from the 429.03 mg/m³ observed in pure coal combustion.