Dust returning method for fluidized bed, and fluidized bed gasifier based on same

Abstract

The invention relates to a dust returning method for a fluidized bed, and a fluidized bed gasifier based on the same. The method concretely comprises the following steps: a, performing gas-solid separation on fly ash-containing gas generated in the fluidized bed gasifier for at least one time to collect fly ash; and b, mixing the collected fly ash with raw coal, then delivering the obtained mixture into the gasifier, and combusting and gasifying the mixture. The fluidized bed gasifier comprises a cylindrical shell, the top of the cylindrical shell is provided with a gas outlet, the bottom of the cylindrical shell is provided with a slag discharge port, the sidewall of the cylindrical shell is provided with a coal feeding tube, the gas outlet is communicated with the feed port A of a first-stage cyclone separator, the gas outlet A of the first-stage cyclone separator is communicated with the feed port B of a waste heat boiler, the discharge port of the waste heat boiler is communicatedwith the feed port C of a second-stage cyclone separator, the gas outlet B of the second-stage cyclone separator is communicated with the feed port D of a bag-type dust remover, the ash discharge portA of the first-stage cyclone separator is communicated with the inside of the cylindrical shell, the ash discharge port B of the second-stage cyclone separator and the ash discharge port C of the bag-type dust remover are respectively communicated to a dust return pipeline, and the dust return pipeline is communicated with the coal feeding tube.

Description

Technical field: [0001] The invention belongs to the technical field of coal gasification, and in particular relates to a powder returning method of a fluidized bed and a fluidized bed gasification furnace based on the method. Background technique: [0002] The fluidized bed gasification furnace is widely used in the field of coal gasification. The fluidized bed gasification furnace includes a cylinder. The upper and lower ends of the cylinder are respectively equipped with a gas outlet and a slagging outlet. The pipe injects gasification agent into the gasifier, and the coal in the gasifier circulates under the drive of the airflow, and at the same time, the high-temperature bed material reacts to generate gas, which is discharged from the gas outlet. [0003] During the combustion and gasification process of the bed material, a large amount of fly ash (coal powder) will be formed, and these fly ash will be discharged from the gas outlet together with the gas. These fly ash...

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Problems solved by technology

[0004] The traditional powder return method is to collect the fly ash and put it directly into the gasifier through the powder return pipe connected to the side wall of the gasifier or the gas distribution plate, mix it with the bed material in the furnace, and flow to the high temperature with the bed material. After the central jet area, it can be ignited by the burning bed material to burn and gasify again, which causes the fly ash to exist in the gasifier for a long time without reacting, which reduces the reaction efficiency of the gasifier, and, Since the fly ash is burnt coal, the surface of the fly ash is covered with fixed carbon that is difficult to burn and gasify. Although it takes a long time to be ignited around the burning coal

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