Investigation of the Products and the Migration of Sodium and Chlorine During Pyrolysis of High-Sodium Coal Mixed With Phosphorite

The impact of adding phosphorite during the pyrolysis of high-sodium Shaerhu coal to address severe deposition and corrosion issues caused by the release of volatile sodium and chlorine compounds was explored. During pyrolysis, sodium compounds volatilize and condense on cooler surfaces, leading to deposits that corrode metal and reduce boiler efficiency. By copyrolyzing phosphorite with coal, the study finds that tar yield decreases, whereas char yield increases, with slightly improved char reactivity. The pyrolysis gas yield also increases, with higher concentrations of methane and hydrogen, enhancing energy utilization. Calcium compounds in phosphorite react with sodium chloride and sodium sulfate, forming high-melting-point, insoluble sodium compounds and water-soluble chlorides, thereby reducing the release of sodium and chlorine. This reduces fouling and corrosion, improving equipment efficiency. Additionally, recycling copyrolyzed phosphorite for yellow phosphorus production can enhance conversion ratios, supporting the production of higher-value phosphorus chemicals.