Method and device for producing dimethyl ether by gaseous phase dehydration of methanol under pressurized conditions

Abstract

The invention relates to a method and a device for producing dimethyl ether by the gaseous phase dehydration of methanol under pressurized conditions. The method is as follows: two separate structures for preheating and gasifying methanol under atmospheric pressure are taken as an upper structure of a methanol gaseous phase dehydration device, and medium pressure steam is used to heat; the middlelower part of the device is taken as a reaction section in which a catalyst and a cooling coil pipe are arranged; and when the temperature of materials at the reaction section is reduced to an appropriate reaction temperature, the materials enter the next reaction section, and the number of reaction sections can be adjusted according to facts. The device designed according to the method comprisesa cylinder, an upper end enclosure, a methanol gasification section, 1 to 3 reaction sections and a lower end enclosure, wherein the reaction sections are separated by supporting plates, and the volume of the catalyst filled at each reaction section is same, or gradually increased or decreased; and reaction products finally enters a separating working procedure through a reactant outlet. The invention has the advantages that the device for producing dimethyl ether by the gaseous phase dehydration of methanol under pressurized conditions has small occupied space, simple structure, fully reasonable utilization of heat, and easy large scale of equipment.

Description

【Technical field】 [0001] The invention relates to the technical field of chemical reaction equipment, in particular to a production method of dimethyl ether (DME), in particular to a method and a device for producing dimethyl ether by gas-phase dehydration of methanol under pressurized conditions. 【Background technique】 [0002] Dimethyl ether is an ideal clean fuel, which can be used as civil fuel and automobile fuel, and is a substitute for chlorofluorocarbons, which can reduce the damage to the atmospheric ozone layer; dimethyl ether can also be used as a spray carrier in the aerosol industry It is used as a raw material for the production of low-carbon olefins. As a raw material for clean fuel and low-carbon olefins, DME has a huge market. [0003] At present, the reactor types used for methanol dehydration to produce DME mainly include: [0004] (1) The traditional liquid-phase dehydration method using concentrated sulfuric acid as a catalyst in a fully mixed tank rea...

AI Technical Summary

Problems solved by technology

However, due to the characteristics of the fully mixed tank reactor, the added methanol cannot be reacted quickly, causing a lot of methanol to volatilize with the dimethyl ether. Therefore, it is necessary to increase the rectification device to separate and recycle the methanol, which makes the dimethyl ether The production process is complicated, which increases the production cost

[0005] (2) The Chinese patent document CN1194257 proposes the reaction process equipment for synthesizing dimethyl ether in the slurry bed under the near methanol critical state, because it proposes harsh requirements to the production equipment, there is no implementation report at present

[0006] (3) The Chinese patent document CN1907932A reports a method for producing dimethyl ether from methanol, but since the reaction is carried out at 120-220°C, methanol is mixed in liquid phase or gas-liquid phase at this temperature When the state enters the reactor, the contact area between methanol and catalyst is small, so the production capacity of a single reactor is limited

[0007] (4) Chinese patent document CN2900523Y has proposed a kind of methanol gas-phase production dimethyl ether reactor with heat exchange section, since the heat of reaction of methanol dehydration to produce dimethyl ether is very small, in the case of small dimethyl ether production Under normal circumstances, the heat released during the reaction process is not only difficult to heat the inlet gas-phase methanol steam, but may even cause the gas-phase methanol steam to condense due to poor insulation effect of the reactor; at the same time, since this type of reactor is operated under normal pressure, With the increase of dimethyl ether production, its volume is also increasing, which cannot meet the requirements of large-scale production of dimethyl ether

[0008] Since the above reactors for methanol dehydration to produce dimethyl ether are all operated under normal pressure, whether it is the preheating and gasification of raw material methanol before the reaction, or the recovery of the reaction heat of the product after the reaction, it is all under normal pressure. Low-energy heat, the entire process requires multiple heat exchangers around the reactor, so the investment in equipment is greatly increased

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