System and operating method for removing light oil impurity by methanol rectification

Abstract

The invention relates to a system and an operating method for removing light oil impurity by methanol rectification. The system comprises a pre-rectifying tower, a first condenser, a second condenser, a first oil-water separating tank and a second oil-water separating tank; and the second oil-water separating tank is arranged at the back of the first condenser, the first oil-water separating tank is arranged at the back of the second condenser, and extraction water is added into condensate of the first condenser and condensate of the second condenser respectively. The amount of the water added into the condensate of the first condenser is 5 to 10 percent of crude methanol fed into the pre-rectifying tower, and the amount of the water added into the condensate of the second condenser is 1 to 5 percent of crude methanol fed into the pre-rectifying tower. By adopting the operating condition of the system, the extraction water is added in back of the condenser and front of the oil-water separating tank by changing the adding mode from the upper part of the pre-rectifying tower; and the water-insoluble light oil impurity contained in the tower top steam is thoroughly separated out under the condition of not losing the methanol. The invention is applicable to a device for preparing the methanol by using coal and oven gas as raw materials.

Description

technical field [0001] The invention relates to a system and an operation method for removing light oil impurities by methanol rectification, and belongs to the technical field of chemical separation. Background technique [0002] Since the 1950s, natural gas has gradually become the main raw material for methanol production, because it simplifies the process, facilitates transportation, and reduces costs. At present, about 70% of the world's total methanol production is based on natural gas. However, with the shortage of energy sources, coal gasification technology has developed rapidly, and its industrial application has also made great progress. From a long-term strategic point of view, the reserves of coal in the world far exceed that of natural gas and oil, especially in my country. In the future, the raw material route of producing methanol from coal will eventually dominate. [0003] Natural gas, coal, coke oven gas, etc. produce methanol. After the methanol synthesi...

AI Technical Summary

Problems solved by technology

In the initial stage of the catalyst in the methanol synthesis reaction, there are few impurities produced by the reaction, and the product quality is not a big problem at this time. However, when the catalyst is aging and the reaction produces more impurities in the later stage of the methanol synthesis reaction, if the pre-distillation tower is not sensitive to these impurities Incomplete removal will directly affect the quality of methanol products

In this case, if the light oil impurities are to be completely removed, the condensate of the second condenser cannot be returned to the reflux tank, thereby losing the methanol in it

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