Large-size low-temperature destructive distillation system for low-order lignite

Abstract

The invention provides a large-size low-temperature destructive distillation system for low-order lignite, solving the problem of industrial destructive distillation of low-order lignite. The system consists of a lignite preparation part, a drying part, a destructive distillation part, a heat source part, a semicoke cooling and transporting part and a gas and tar treatment part, wherein in the lignite preparation part, raw lignite is smashed and then fed into the drying part for drying; dried lignite particles are fed to the destructive distillation part for destructive distillation; the gas obtained after destructive distillation is dedusted and then enters into the gas and tar treatment part to be treated and then stored; air cooling is carried out on the semicoke subjected to destructive distillation and then the semicoke is discharged; the destructive distillation heat source is supplied by high-temperature smoke produced by combusting partial destructive distillation self-produced gas in a combustion furnace; low-temperature waste smoke extracted from the destructive distillation part is used as the heat carrier of the drying part; and cold air for cooling the semicoke is introduced into the combustion furnace after absorbing the heat of the semicoke for combusting the gas. The large-size low-temperature destructive distillation system is suitable for large-scale industrial continuous production, has simple equipment and is easy to implement, thereby providing an effective way for the utilization of the low-order lignite.

Description

technical field [0001] The invention relates to a dry distillation technology, in particular to a large-scale low-temperature dry distillation system for upgrading low-rank lignite. Background technique [0002] Faced with the increasing shortage of coal resources, the utilization of lignite, a low-rank coal resource that was not mentioned by people, is now gradually put on the agenda. Lignite has low degree of coalification, high moisture, easy weathering and fragmentation in the air, low calorific value, and inconvenient long-distance transportation. Therefore, it is necessary to find a reasonable and economical way to utilize this coal. Considering coal type restrictions, environmental protection, processing intensity and process efficiency, and taking into account the properties of lignite itself, that is, the tar yield in lignite is not only higher than that of bituminous coal, but also has no caking property, low-temperature carbonization technology is selected as the ...

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Problems solved by technology

[0004] 1. Considering the type of process, the existing dry distillation system can be divided into internal heating type, external heating type, and internal and external heating type according to the heating method; according to the type of heat carrier, it can be divided into solid heat-carrying type, gas heat-carrying type, gas-solid Heat-carrying type, the heat of the traditional external heat-type retort system only enters through the heat-conducting wall, the heat utilization rate is low, and the uneven heating causes uneven semi-coke quality. Reduced tar yield

In the internal thermal dry distillation system using flue gas as the heat carrier, the volatile products released by coal thermal decomposition are diluted by the flue gas, which reduces the quality of the coal gas and increases the crude gas separation and purification equipment and power consumption; at the same time, there is a large amount of volatile matter in the dry distillation stage. If the flue gas is used as an oxygen-containing heat medium at this stage, it will easily cause volatile matter to burn or even explode, affecting the normal and stable operation of the system

The retort system adopts solid heat transfer (such as ceramic balls, sand, etc.), the separation and circulation of ceramic balls or sand need to use special high-temperature screens and elevators, the investment and maintenance costs are high, and there is heat carrier wear that causes semi-coke Problems such as excessive ash content

If semi-coke is used as the heat carrier, oxygen-deficient combustion measures should be supplemented, otherwise there will be an unfavorable tendency of semi-coke burning and reducing its calorific value. At the same time, the semi-coke produced by this process contains a large amount of powder coke, which reduces the product quality.

[0005] 2. Considering the way of coke quenching: Taking the most commonly used wet coke quenching as an example, about 0.5t of steam containing a large amount of phenol, cyanide, sulfide and dust will be discharged for every ton of red coke quenched, which seriously pollutes the At the same time, the atmosphere and the surrounding environment cause a lot of waste of semi-coke sensible heat, which reduces the heat utilization efficiency of the entire system

[0006] 3. Considering energy and resource recycling: For low-rank coal with high moisture content, after drying, this moisture takes away a lot of heat in gaseous form, resulting in huge energy loss. Generally, the upgrading system does not convert the raw coal itself. Use of water, causing waste of resources

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