COMBUSTION AND SULFUR RETENTION CHARACTERISTICS OF BIOMASS COMPOUND COAL

摘要

A kind of clean fuel, biomass compound coal (BCC), was prepared from Xianfeng lignite in combination with biomass such as agricultural residues, forestry wastes, municipal solid wastes (MSW), etc. Experiments were carried out by increasing the temperature from 20 to 700°C at heating rate of 10°Cmin~(-1) and at atmosphere pressure in a Simultaneous Thermal Analyzer. Biomass fractions of 0wt%, 20wt%, 40wt%, 60wt% and 100wt% were used in experiments. Based on simultaneous thermal analysis (STA), it was revealed that the combustion process of BCC can be broadly separated into four stages, and BCC has some better combustion characteristics than the Xianfeng lignite and the biomass individually, i.e. lower ignition point, low ash content and higher sulfur fixation ratio. Based on the experimental results, it is clear that there were interaction between biomass and Xianfeng lignite during the combustion. The sulfur retention characteristics of BCC were also studied. The experimental results show that BCC has higher sulfur retention ratio comparing with conventional briquettes. When the Ca/S is equal to 2.0 and combustion temperature is below 900°C, the sulfur retention ratio can reach 90% or more. It was indicated that the sulfur retention ratio of BCC increases with a rise in Ca/S, and decreases with a rise in combustion temperature. And it tends to obtain maximum when Ca/s is 2.0.