Two-stage gasification method and gasification device for fuels with wide size distribution

Abstract

The invention relates to a two-stage gasification method and a gasification device for a fuel with wide size distribution. The two-stage gasification method for the fuel with wide size distribution comprises the steps of 1) adding the fuel to a fluidized bed pyrolyzer by a feeding device; adding a gasifying agent to the fluidized bed pyrolyzer; drying / pyrolyzing or partly gasifying the fuel under semicoking of the pyrolyzer and heating of the gasifying agent; and 2) sending the solid and gas generated in the step 1) to a fluidized bed gasification furnace, adding the gasifying agent to the fluidized bed gasification furnace, finishing complete gasification of semicoke; removing tar by high-temperature pyrolysis, part oxidization and semicoke catalytic reforming in the fluidized bed so as to produce clean gas. With the adoption of the method, the traditional fuel gasification process is divided into a material pyrolysis stage and a semicoke gasification stage, which are performed in an upper fluidized bed pyrolyzer and a lower fluidized bed gasification furnace.

Description

technical field [0001] The invention relates to the technical field of clean energy, in particular, the invention relates to a two-stage gasification method for fuel with wide particle size distribution and a gasification device thereof. Background technique [0002] Gasification is one of the leading ways to convert carbon-containing fuels such as coal and biomass, and is an important technical means to realize their comprehensive and clean utilization. This technology is widely used in chemical industry, metallurgy, civil and industrial gas, building materials, ceramics and other fields. It is a leading technology for the development of these industries and an important measure to reduce environmental pollution, save energy and develop industries. At present, the fixed-bed gasifiers commonly used in the domestic gas industry are backward in technical level, and generally have problems such as poor raw material applicability, small processing capacity, difficult amplificati...

AI Technical Summary

Problems solved by technology

Due to the limitation of the external heating spiral pyrolyzer, the technology developed by DTU in Denmark is difficult to further scale up

In addition, this process is only suitable for processing raw materials with large particle size (25mm×35mm×6mm), and the requirements for raw material size are relatively high

Although the two-stage gasification technology developed by the University of Seoul in South Korea can process a large amount of raw materials, it greatly increases the cost of raw materials because it does not make full use of the semi-coke produced by the gasifier itself (using a large amount of commercial activated carbon).

The two-stage gasification technology announced in Chinese patent 94190559.4 is due to the direct discharge of pyrolysis gas generated by the fluidized bed, resulting in excessive tar content in the mixed gas. In practical applications, post-installed gas purification facilities are still required, which undoubtedly increases equipment cost

In the two-stage biomass gasification process disclosed in Chinese patent CN1583956A, due to the lack of catalytic action of semi-coke produced in the previous gasification stage, the final synthesis gas product will still have a relatively high tar content, and the possible carbon conversion rate is also low. will be particularly high

The two-stage gasification process announced by Chinese patent CN101440307A, due to the limited effect of high-temperature pyrolysis on tar removal, and the large soot content in the gas after pyrolysis, inevitably reduces the conversion rate of carbon and increases the subsequent purification. equipment investment

The two-stage gasification process announced by Chinese patent CN191612, in the actual application process, because the small particle semi-coke produced by the fluidized bed directly enters the downdraft fixed bed, resulting in poor ventilation of the fixed bed and a large bed pressure drop , has an impact on the long-term stable operation of the device

Compared with foreign two-stage gasification technology, the 4 published Chinese patents are more suitable for scale-up, but further improvement is needed in terms of tar removal efficiency or operational stability

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