Multi-effect rectifying process of methanol

Abstract

The invention relates to a multi-effect rectifying process of methanol, which belongs to the technical field of separation and purification of chemical products. In the process, a crude methanol raw material of coal-to-methanol is rectified by a pre-rectifying tower, a pressurizing tower I, a pressurizing tower II, an atmospheric tower and a recovery tower in turn at appropriate temperature and pressure so as to obtain a high-purity refined methanol product according with quality requirements. In the flow, methanol steam on the top of the pressurizing tower I is used for providing heat for a reboiler at the bottom of the pressurizing tower II, the methanol steam on the top of the pressurizing tower II is used for providing heat for a reboiler at the bottom of the atmospheric tower, and the pressurizing tower I, the pressurizing tower II and the atmospheric tower form multi-effect rectification; and simultaneously, the methanol steam on the top of the recovery tower is used for providing heat for a reboiler at the bottom of the pre-rectifying tower, and the recovery tower and the pre-rectifying tower form double-effect rectification. The invention provides an energy-saving methanol multi-effect rectifying process method which has the advantages of greatly reduced energy consumption, more stable production process, more easily controlled product quality, higher methanol recovery rate and basically equivalent investment compared with a three-tower rectifying process.

Description

technical field [0001] The invention belongs to the separation and purification technology of chemical products, and in particular relates to a methanol multi-effect rectification process. Background technique [0002] In recent years, with the rapid development of coal chemical industry at home and abroad, the processing scale of methanol rectification unit has been greatly increased, and the quality requirements for refined methanol products are also more stringent. At present, the scale of most of the methanol plants under construction in China is between 100,000 and 600,000 tons per year, while there are million-ton methanol plants in foreign countries; the content of ethanol in refined methanol products is generally required to reach 25mg / kg (Even below 10mg / kg), the content of acetone is required to reach below 10mg / kg, in order to meet the needs of methanol downstream product production. Although the traditional methanol single-tower rectification process and double-...

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Problems solved by technology

Although the traditional methanol single-tower rectification process and double-tower rectification process have relatively low investment, due to their relatively poor product quality, low methanol recovery rate, and especially their high energy consumption, they have been basically adopted by Lurgi The methanol three-tower rectification process developed by the company and the four-tower rectification process (three towers plus recovery tower) replaced

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