Double-efficient energy-saving and water-saving rectifying system and process for methanol

Abstract

A methanol dual-effect rectification energy and water saving system and process are disclosed. The system consists of crude methanol pre-heater, pre-rectification tower, methanol pre-heater, pressurizing tower, normal-pressure tower, re-boiler, condensing re-boiler and methanol recovering tower. The side producing pipe of normal-pressure tower is connected to cooler, which is connected with feed port of recovering tower, the bottom of normal-pressure tower is connected to solution containing alkaline salt producing pipe, side line of recovering tower is connected with potato spirit producing pipe, and effluent blow-off pipe on bottom of tower is communicated with extracting pipe of pre-rectification tower. It has less consumption and saves extracting water.

Description

technical field [0001] The invention relates to the technical field of purification of chemical products, in particular to an energy-saving and water-saving system and process for methanol double-effect rectification. Background technique [0002] Methanol is a very important basic chemical raw material, as well as a clean energy and power fuel with excellent performance, which plays a pivotal role in the current global chemical product market. Rectification is a very important chemical unit operation in methanol production, which is directly related to product quality, environmental protection, energy consumption and production costs. Therefore, saving energy and water consumption in the rectification process is the key to promoting methanol production. The important technical link of further development has attracted more and more people's attention. [0003] The rectification units in the existing methanol plants in my country are roughly ...

AI Technical Summary

Problems solved by technology

The former has the advantages of simple process, convenient operation, stable operation, etc., but has the defect of high energy consumption; the latter such as figure 1 The schematic diagram of the double-effect rectification process shown in the figure uses the condensation heat of the methanol vapor at the top of the pressurized column as the heat source for the reboiler of the atmospheric column to form a double-effect rectification and realize the full use of heat, which not only saves steam, but also to a certain extent Compared with the single-effect process, the energy consumption can be reduced by about 30%, so this process is the most commonly used distillation process at present.

However, it can be seen from the analysis that there are still many links to be improved in the double-effect distillation

Taking the distillation process of three plus one tower as an example, the bottom discharge of the atmospheric pressure tower is usually used as the feed of the recovery tower. This process has certain limitations: ① Since the concentration of methanol in the bottom discharge of the atmospheric pressure tower is much lower than that Therefore, if the recovery tower wants to achieve the ideal separation effect, the reflux ratio must be increased, which increases the load of the recovery tower; ② a large amount of salt and excess alkali produced in the pre-distillation tower are brought into the recovery tower, resulting in The waste liquid discharged from the bottom of the recovery tower contains a high concentration of saline-alkali components and cannot be recycled. It can only be sent to the sewage treatment plant, causing a lot of waste

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