Three-fluidized-bed solid heat carrier coal pyrolysis, gasification and combustion cascade utilization method

Abstract

The invention discloses a three-fluidized-bed solid heat carrier coal pyrolysis, gasification and combustion cascade utilization method. The method comprises the following steps of: mixing coal and high temperature circulating ash serving as a solid heat carrier in a fluidized bed pyrolysis furnace, pyrolyzing to separate out volatile, cooling and separating the volatile to obtain tar and pyrolysis gas, conveying pyrolysis semi-coke generated by pyrolyzing the coal to a fluidized bed gasification furnace, performing gasification reaction by using water vapor and O2 as gasification agents to prepare synthesis gas, conveying the semi-coke which is incompletely gasified in the gasification furnace to a circulating fluidized bed combustion furnace, blowing air for the conventional combustion or blowing O2 / CO2 for oxygen-enriched combustion, heating the circulating ash serving as the solid heat carrier, and producing gasification agent vapor required by the gasification furnace by using high temperature flue gas generated by combustion. The method has the advantages that: the tar, the pyrolysis gas and the synthesis gas are co-produced through coal pyrolysis, gasification and combustion cascade utilization, the gasification condition of the semi-coke is reduced, and good economic benefits and social benefits are achieved.

Description

technical field [0001] The invention relates to the field of coal cascade transformation and utilization, in particular to a cascade utilization method for pyrolysis gasification combustion of solid heat carrier coal in three fluidized beds. Background technique [0002] my country is rich in coal resources. According to statistics, as of the end of 2007, my country's proven reserves of coal resources were 1.18 trillion tons, including 326 billion tons of basic reserves and 854 billion tons of resources. At present, my country's coal resources can basically meet domestic demand, but it needs to import a large amount of oil from abroad every year. In 2010, my country's dependence on foreign oil has reached 55%, and according to CNPC's forecast, during the "Twelfth Five-Year Plan" period, my country's foreign dependence on oil will reach 60%. In addition, about one-fifth of the petroleum consumed in my country every year is used as chemical raw materials to produce chemical ...

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Problems solved by technology

[0003] At present, the utilization method of coal resources is still dominated by direct combustion, which has low efficiency and serious pollution. However, complete coal gasification and liquefaction have high operating conditions, large equipment investment, high operating costs, and relatively high requirements for coal quality. advanced questions

The existing coal combustion and gasification technologies treat coal as a single substance and transform it. Combustion uses various components contained in coal as fuel, and does not effectively utilize components with higher utilization value. Although gasification can utilize coal resources with high efficiency and low pollution, the reaction rate of fixed carbon in the gasification process slows down with the increase of conversion degree. If a complete or high conversion rate is to be obtained in a single gasification process, high temperature is required. , high pressure, and long residence time, which lead to a complex and large gasification system, increased costs, and high requirements for coal quality

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