EXPERIMENTAL RESEARCH ON CFB COAL PYROLYSIS AND COMBUSTION POLYGENERATION TECHNOLOGY

摘要

A new poly-generation system combined coal combustion and pyrolysis has been developed for clean and high efficient utilization of coal.Coal is first pyrolysed in a fluidized pyrolyzer and produced gas is then purified and used for chemical product or liquid fuel production.Tar is collected during purification and can be processed to extract monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) etc.and to make liquid fuels by hydro-refining;semi-coke from the pyrolysis reactor is burned in a circulating fluidized bed (CFB) combustor for heat or power generation (Fig 1).The system has following advantages: 1)It produces not only power, but also tar and gas, which can be converted as chemicals, liquid fuels, city gas or syngas, etc.So it provides a promising alternative energy.2) Good fuel adaptability.Most bituminous coal and lignite coal can be used.3) Using staged conversion technology, valuable fractions of coal, such as the volatile fraction, are extracted and semicoke is burned at boiler.Coal composition is fully utilized.4) Most of sulfur compounds, nitrogen bases, and undesirable pollutant are removed during the pyrolysis.Therefore, pollutant emission from the boiler is very low.A 12 MW demonstration project, designed by Zhejiang University in cooperation with the Huainan Mining (Group) Co., Ltd.had been erected and operated successfully from August 2007.Many tests had been conducted at this system.The experimental study focused on the two fluidized bed operation and characterization of gas, tar and char yields and compositions.The results showed that the system could operate stable, and produce about 0.12 Nm3/kg gas with 22 MJ/Nm3 heating value and about 10 wt ％ tar when using Huainan bituminous coal under pyrolysis temperature between 500～500℃.The produced gases were mainly H2, CH4, N2, CO, CO2, C2H4, C2H6, C3H6 and C3H8.The CFB combustor can burn semi-coke steadily, whether the pyrolyzer run or not, and produced 12 MW electricity.