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The ash characteristics is closely related to the fuel compositions, and chemical reactions happened between the compounds of ash during co-combustion of biomass and coal. Through the phase compositions analysis of ash from co-combustion of biomass and coal, the results show that KCl(g)mainly reacts with aluminosilicates to form potassium-aluminosilicates and part of KCl(g)also can be sulfated by SO2during co-combustion. In the fuel, CaO and MgO may react with aluminosilicates to form CaAl2Si2O8and Mg3Al2Si3O12with low melting temperature, which can reduce the content of potassium-aluminosilicates and drop the ash melting point temperature.

This paper focuses on the problems of ash deposition and corrosion caused by alkali metal chloride in biomass boiler. Kaolin, pulverized coal ash, silica fume, dolomite, limestone and bauxite are used as additives in this study, to investigate the degree of corrosion of four metal materials on biomass boiler. The results show that the corrosion rate of metal samples is significantly reduced after adding additives. Kaolin, pulverized coal ash, silica fume and bauxite show much obvious effect on corrosion inhibition. Corrosion resistance of four pipe metals: T91>15CrMoG>12CrMoVG>20G, in which the corrosion resistance of T91 is much better than the other three metals.

In this paper, the characteristics of SO2 and NO release during combustion of lean coal with different coal rank were experimentally studied in the one-dimensional furnace for pulverized coal combustion. The results showed: The coal property and proportion of the component coals have great influence on the characteristics of SO2 and NO release. The releasing concentration of SO2 and NO distributing along the furnace height is generally between that of component coals, and the releasing characteristics of SO2 and NO would be more near to that of the larger proportion coal. The measuring value of the formation concentration of SO2 and NO are different from the calculating value based on the weighted means of the component coals to a certain extent. While the different coal are added to lean coal, the time corresponding with peak value releasing concentration of SO2 and NO is different.

In this paper, three detection methods were analyzed to determine the chlorine precipitation from the flue gas: Silver nitrate volumetric analysis (SNVA), Volhard method (VM) and Mercuric thiocyanate spectrophotometric method (MTSM). Results indicated that SNVA and VM were simple and convenient, but unsuitable for the detection of blend fuel due to the high lower limit. MTSM was suitable for biomass and coal co-combustion for its low lower limit and high sensitivity. In addition, MTSM needed less sample solution, which made it more suitable for multiple measurements to reduce errors, and the maximum proportional error was only 3.5%.