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Experimental Study on CFB Heat Electricity Gas Tar Multi-generation Technology

Author: WenLiang
Tutor: FangMengXiang;LuoZhongZuo
School: Zhejiang University
Course: Engineering Thermophysics
Keywords: circulating fluidized bed poly-generation pyrolysis temperature coal rank
CLC: TK121
Type: Master's thesis
Year: 2010
Downloads: 44
Quote: 0
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Abstract

According to the characteristics of China’s energy consumption, coal will be remaining the most important primary energy of China for a long period of time. At present, the main form of China’s coal utilization is direct combustion; this approach not only reduces the coal utilization, but also brings heavy pressure to environmental protection. The circulating fluidized bed poly-generation technology developed by Zhejiang University can achieve heat, electricity, gas, tar cogeneration in a system, using such a method can achieve the classification of coal conversion and utilization, so the value of coal utilization can be increased significantly.The pyrolysis characteristics of coal are the basis of poly-generation technology. In this paper, the characteristics of coal pyrolysis were studied in an experimental fluidized bed device. The effects of temperature and coal type on pyrolysis gas and tar were investigated; there is a maximum tar yield with increasing pyrolysis temperature, due to the presence of secondary reaction, the high pyrolysis temperature is negative to the generation of tar. At low temperature, gas compositions mainly contain CO and CO2, H2 concentration increases with increasing temperature continuously.CO2 content in a downward trend with increasing temperature. The higher the oxygen content in the coal, the more the CO and CO2 contained in pyrolysis gas, too high or too low O/C ratio is negative to the generation of CH4. The higher H/C the coal, the more lightweight components contained in pyrolysis tar. High rank coal pyrolysis tar mainly composed by aromatic hydrocarbons, and low rank coal pyrolysis tar mainly composed by aliphatic hydrocarbons.The pyrolysis characteristics of different coal were studied in a 1MW poly-generation device. The influences of gasification temperature on the pyrolysis gas and yield of tar were researched; the experiment results show that there is a maximum tar yield with increasing gasifier temperature; the pyrolysis gas mainly contains H2 and CH4, With gasifier temperature increasing, H2 and CO concentrations increase continuously; 1MW poly-generation experiment provide a basis for further applications in industry.12MW poly-generation results show that the pyrolysis tar is a very good chemical raw material. With the gasifier temperature increasing, pyrolysis tar’s H/C ratio decreased, viscosity and softening point rise, tar-quality get worse. So the gasifier temperature should be properly controlled which can make the tar quality and quantity achieve the best point. The poly-generation system can reduce NOX, SOX and other pollutant emissions effectively; the system has the characteristics of stable, safe, reliable, convenient adjustment and stability of tar and gas production.12MW poly-generation experiments verify the thermal, electric, gas, tar poly-generation technology is an advanced technology which is feasible to promote in the industry.

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CLC: > Industrial Technology > Energy and Power Engineering > Thermal engineering, heat > Thermal Engineering Theory > Engineering Thermophysics
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