Method and device for recycling and extracting lightweight oil to regenerate methanol

Abstract

The invention discloses a method and a device for recycling and extracting lightweight oil to regenerate methanol. The method comprises the following steps: S1: cooling and condensing oil-containing coal gas to separate out lightweight oil; S2: separating oil coal gas by adopting a pre-washing tower, and cooling the cooled and condensed to a set temperature; S3: introducing the cooled coal gas to a methanol pre-washing tower, and adopting cold methanol to wash and absorb the coal gas; S4: heating the methanol which absorbs the lightweight oil and then discharging the methanol into a flash evaporator to perform gas separating and recycling; S5: discharging water and methanol discharged out of the flash evaporator into an extractor for extracting to obtain an oil phase and a water phase; S6: rectifying the water phase to separate out lightweight oil and a methanol solution, and returning the separated lightweight oil back to an extractor for extraction; and S7, rectifying the methanol solution to separate out methanol and water. The method disclosed by the invention is high in lightweight oil recovery rate and the recovered lightweight oil is high in quality.

Description

technical field [0001] The invention relates to the field of purification of coal gas produced by coal gasification, in particular to a method and device for recovering light oil and extracting and regenerating methanol. Background technique [0002] For some coal gasification technologies, such as pressurized fixed bed coal gasification technology, multi-stage pressurized fluidized bed coal gasification technology, etc., some by-products with high economic value are produced during the coal gasification process, which must be effectively separated and recovered. , to improve the economics of gasification technology, while avoiding difficulties in gas purification or environmental pollution. [0003] Some by-products include tar products, medium and light oil products or the transport media used in the gasification process itself. It is generally defined that tar is an organic substance with a density higher than water, and medium oil is an organic substance with a density ...

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Problems solved by technology

[0005] 1. The existence of the above-mentioned oils in the gas will cause the equipment to be dirty and block, and reduce the performance of the equipment, such as the heat transfer performance of the heat exchanger, the separation performance of the washing absorption tower, etc.

[0006] 2. If a large amount of oil in the gas is not completely removed, it will cause pollution to the low-temperature methanol washing main washing methanol circulation circuit, which will reduce the purification performance of the low-temperature methanol washing

[0007] 3. In order to completely remove the oil in the gas, the amount of normal-temperature methanol or low-temperature methanol required for conventional washing is relatively large, resulting in a large capacity and consumption of the regeneration device of methanol liquid, and a large amount of methanol circulation

[0008] 4. The light oil recovered by the traditional method contains methanol, resulting in a decline in the quality of the light oil or difficulty in recycling

[0009] 5. The methanol contained in light oil also causes the loss of methanol

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