Gas purification process and system

Abstract

The invention relates to a gas purification process and a system, which solve the problem that the existing gas purification process is complex in process, large in waste water amount, high in production cost, poor in dedusting effect and low in coal tar quality. The technical scheme is that raw material coal is predried in a dryer and then sent to a high temperature pyrolysis furnace for pyrolysis, untreated gas containing ash and coal tar and produced through pyrolysis is sent to a high temperature cyclone separator to remove ash in large particles, dedusting of the untreated gas after removing the ash in large particles is further carried out through a high temperature filter, gas is carried out waste heat recovery through a waste heat boiler after dedusting, the gas which exchanges heat to the temperature of 300-350 DEG C enters a chilling tower and is contacted with coal tar oil at the temperature of 40-80 DEG C in an adverse current mode so as to conduct washing and cooling, the coal tar contained in the gas enters the coal tar oil and is discharged from a tower bottom, the gas is washed and cooled to 40-100 DEG C at the tower top to obtain clean gas, and the clean gas is sent to a gas cabinet. The gas purification process and the device are simple, free of waste discharge, good in gas dedusting effect, high in byproduct coal tar quality and low in production cost.

Description

technical field [0001] The invention relates to a gas purification process and system in the chemical industry. Background technique [0002] Clean fuel or other primary chemical products obtained from raw coal through gasification or pyrolysis have broad application prospects in our country. The raw coal gas produced during the coal gasification or pyrolysis process contains a large amount of dust, water vapor mixed with dust, and organic impurities such as tar. In order to produce clean gas suitable for sale or meet downstream processes, it is also considered to recycle the raw gas The tar by-product must be purified for crude gas. [0003] At present, the most common process steps in the gas purification process are pyrolysis, cyclone dust removal, heat exchange, washing, electric dust removal, and tar recovery by electric tar collector. Taking the pyrolysis process of Ende furnace as an example, refer to figure 2 After the raw coal enters the pyrolysis furnace, ash-con...

AI Technical Summary

Problems solved by technology

There are many problems in this process, mainly as follows: (1) Gas dust removal effect is poor and efficiency is low: the particle size distribution of dust in gas is very wide, there are larger granular dust and very fine dust, while the current traditional The gas purification process of coal pyrolysis usually only uses the method of water washing after cyclone separation and then electric dust removal to wash and purify the gas. Due to the limitation of the separation efficiency of the cyclone separator and its critical particle size, the dust separation effect is poor, even if the accumulation of two cyclone separation And after electrostatic precipitating, the gas usually contains more fine dust, and the washing process with water must be added, and the effect is still not good, which makes the dust removal process extremely complicated, prolongs the treatment cycle, and increases the production cost

(2) Low recovery rate and poor quality of by-product tar: On the one hand, limited by the separation efficiency and critical particle size of the cyclone separator, the ash content in the by-product tar obtained after electric tar capture is relatively large, and the tar quality is poor; On the other hand, due to the cooling steps such as waste heat boiler and washing tower washing in the early stage, part of the coal tar in the tar-containing gas is condensed and then discharged with dust, which greatly affects the tar recovery rate of the final electric tar collector.

At the same time, the tar mixed in the discharged dust as an impurity also seriously affects the secondary recycling of dust

(3) Large amount of waste water treatment and increased production cost: On the one hand, the raw coal has a high water content (up to 30% or more), and after pyrolysis, a crude gas with a high water content is formed. If the crude gas is directly subjected to dry ash removal , a large amount of condensate formed after cooling will become impurities and be brought into coal tar together, seriously affecting the quality of coal tar, and using a scrubber to wash and cool the crude gas can prevent a large amount of condensate from entering the finished coal tar, but In this process, a large amount of wastewater containing organic matter such as ash, condensate, and tar will be produced. It is difficult to treat a large amount of such wastewater and the process is complicated, which not only increases the production cost of the enterprise, increases the investment in equipment, but also brings heavy burdens to environmental protection. pressure

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