Preparation Of Biomass Compound Coal And Investigation On Its Combustion And Pollution Characteristics

Combustion of fossil fuels, especially coal, is and will probably continue to be an important part of the heat and power production systems of the world. However, the utilization of coal has caused serious environmental impact. It is very imperative to use coal cleanly and sustainablly. Based on summarizing of the many literatures, the status quo of clean coal technology and biomass energy conversion technology were discussed. And then, the conception of biomass compound coal (BCC) was pointed out. The compacting technology process and combustion theory of BCC were analyzed. A new kind of clean fuel, BCC, was developed from Xianfeng lignite in combination with biomass such as agricultural residues, forestry producing wastes, municipal solid wastes. The compressive strength, calorific value of BCC were determined by experiments. The combustion and pollution characteristics were studied. The results of experiments indicate that BCC have higher compressive strength comparing with conventional coal. The combustion characteristics of BCC were studied by using a thermogravimetric analyzer. It has been shown that the combustion process of BCC can be broadly separated into four stages, namely dehumidification, devolatilization and combustion of volatile matter, co-combustion of volatile matter and char, combustion of char. The TG curves of BCC can be divided into two steps clearly, and the DTG curves, DSC curves of BCC have two rate peaks respectively. The more percentage of biomass involved in BCC, the lower ignition points of BCC are. Based on the datum of thermogravimetric analysis, the combustion kinetic parameters of 13CC combustion processes are investigated. It is suggested that the kinetic analysis in combustion of BCC can be handled with the first order reaction. The results of experiments also revealed that BCC have higher sulfur retention quality. When the combustion 4 2001 ~ temperature is controlled below 900 慍 and Ca/S ratio is 2.0, the sulfur fixation ratio of BCC can be achieved 90% or more. The existence of Fe203 can enhance the utilization ratio of sulfur retention additive. Moreover, the emission of flying ash, dust and N~O~ are reduced considerably during the combustion of BCC. In short, BCC is a kind of economical, effective clean coal technology. It will be have a bright utilization future in China.