PM10 emissions from co-combustion of water washed sea rice waste with coal

Abstract

Sea rice is a variety of salt-tolerant rice that absorbs significant quantities of Na, K and Cl. This work investigated effects of water washing pretreatment on sea rice waste properties, such as combustion characteristics, particulate matters (PM) emission and PM10 reduction, during its co-combustion with coal. Fuel characterizations, thermogravimetric analyses, ash fusion temperature (AFT) measurements and PM10 collection experiments were performed. A drop tube furnace was used to burn biomass and blended fuel samples at 1500 °C for PM10 collection. The results show that water washing effectively removed undesirable elements, including K, Na, and Cl. The washing pretreatment increased the AFTs of sea rice straw and ordinary rice straw, but had no effect on the husk. The washing delayed the devolatilization of sea rice waste, as did the char combustion. The yield of PM1 from the washed biomass was significantly reduced owing to the extraction of alkali metals and Cl. During co-combustion with coal, the ash particles of biomass could capture the alkali sulfides from coal, which inhibited the formation of PM1. Ca-containing particles in coal could melt and adhere to the large ash particles from the biomass to grow into larger particles, reducing the yield of PM1–10.