Method and device for coal gasification in combined type fluidized bed

Abstract

The invention discloses a method for coal gasification in a combined type fluidized bed, which comprises coal preparation, gas supply, gasification, slag discharge, dedusting, waste heat recovery and fine powder conveying. An ash agglomeration fluidized bed realizes gasification of large-particle coal; the non-completely converted carryover fine powder enters an entrained flow bed gasifier in a dense phase pneumatic conveying manner; secondary gasification is carried out by using a short retention time high temperature gasification manner; the produced ash slag is carried into an intersection segment of the fluidized bed and the entrained flow bed with high temperature coal gas, and rapidly mixed with ''low temperature'' large-particle partially carbonized coal in the fluidized bed and the produced ''low temperature'' coal gas; and partial ash slag is selectively discharged out of the gasifier in the form of solid. The method and the device of the invention have the advantage of being suitable for various coal types and high in carbon conversion rate.

Description

[0001] Field [0002] The invention belongs to a coal gasification method and device, in particular to a high-efficiency fluidized bed coal gasification method and device that adopt a fluidized bed and an entrained flow bed composite integration. Background technique [0003] Coal gasification is one of the core technologies for efficient and clean utilization of coal, and is the basis for the development of process industries such as coal-based chemicals, coal-based clean fuels, industrial gas and polygeneration systems. [0004] Judging from the current development trend of coal gasification technology at home and abroad, large-scale, pressurized, adaptable to various pulverized coal, low pollution, and easy purification are the development directions of coal gasification. The existing foreign pressurized gasifiers are mainly divided into three categories: pressurized fixed-bed gasifiers (such as Lurgi furnaces), pressurized fluidized-bed gasifiers (HTW) and pressurized entr...

AI Technical Summary

Problems solved by technology

It solves the problem of ash carbon content very well, but the amount of fine powder entrained in gas is high, and the total carbon conversion rate is low (about 90%)

[0006] Since the operating temperature of the fluidized bed gasifier is about 1000°C, under this temperature condition, the coal coke needs to have a residence time of 20-30 minutes to be completely converted, but the fine particles (<0.1mm, accounting for 10% of the total coal input) % or so) in the gasifier is usually within ten to tens of seconds for a residence time, although the fine powder circulation is increased, the total reaction time is short and the carbon conversion rate is low

This part of the unconverted fine powder is taken out of the system, resulting in a decrease in the carbon utilization rate of the fluidized bed

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