Drying Biomass Using Waste Heat from Biomass Ash by Means of Heat Carrier

Abstract

Agricultural and forestry biomass direct-fired power generation represents an important technology to promote low-carbon energy transition and sustainable development. To solve the problems of boiler output fluctuation caused by unstable combustion of high moisture content biomass and insufficient recovery of ash waste heat after combustion, steel heat carriers (HC) were used to absorb high-temperature ash (HTA) waste heat, and then HC was directly mixed with high moisture biomass for dewatering and drying. The thermal efficiency of waste heat recovery decreased with the increase of ash temperature, and the highest thermal efficiency of waste heat recovery was 77.4% at a heat-carrying spheres temperature (THC) of 600 °C and a mixing mass ratio of 3. Through the optimization of waste heat recovery and mixed drying process, at a biomass ash temperature of 800°C, 1 kg of ash was able to dry 0.75 kg of high moisture content biomass, resulting in a reduction in fuel moisture by about 10%.