Sulfate Removal by Kaolin Addition To Address Fouling in a Full-Scale Furnace Burning High-Alkaline Zhundong Coal

Abstract

Zhundong (ZD) coal comes from the largest coalfield in the world with a reserve of 390 billion tons. However, the high content of sodium and calcium in ZD coal causes severe fouling. Presently, no pulverized coal-fired furnace can burn ZD coal alone. In this study, kaolin addition is proposed to address fouling in a full-scale furnace burning ZD coal. Before performing a long-term full-scale furnace test, a series of fundamental studies in a thermogravimetric analyzer (TGA) and drop tube furnace was conducted to demonstrate the effectiveness of kaolin in reducing sulfates. The TGA results show that kaolin addition decreases the decomposition temperature of sulfates in coal ash by higher than 120 °C, and kaolin addition at 1150 °C eliminates all sulfates in the ash. Further experiments on ash deposition and particulate matter (PM) formation in a drop tube furnace at 1350 °C show that kaolin addition successfully eliminates severe ash deposition and fouling on probe surfaces and reduces the amount of PM1.0 ...