Methanol-to-propylene system and method of using it for start-up and feeding

Abstract

The invention provides a methanol-to-propylene system and a method for starting up and feeding materials by using the same. The methanol-to-propylene system includes a first reactor for synthesizing methanol into dimethyl ether to obtain a first product stream; a second reactor for Carrying out the reaction of the first product stream to produce propylene to obtain the second product stream; the first steam pipeline is used to supply steam to the first reactor; the heating device is used to heat up part of the first product stream and the cycle hydrocarbon product stream ; The first and second side line pipelines are used to send part of the first product flow and process water to the second to the last catalyst bed respectively; the refining unit is used to separate the second product flow to obtain C2, A recycled hydrocarbon product stream of C4, C5 and C6 components; a recycled hydrocarbon storage tank for supplying the recycled hydrocarbon product stream to the heating unit. The methanol-to-propylene system and method can control or even prevent the temperature runaway in the first reactor and the second reactor, thereby shortening the start-up and feeding time.

Description

technical field [0001] The invention belongs to the field of methanol-to-propylene production, in particular to a methanol-to-propylene system and a method for starting up and feeding materials by using the same. Background technique [0002] Propylene is one of the most important chemical raw materials, currently mainly derived from FCC (catalytic cracking), naphtha cracking and other petroleum routes. In recent years, the domestic demand for propylene has grown rapidly, but my country's oil production is far from meeting the market demand, and the import rate has exceeded 50%. Under such a situation, the diversification of propylene production raw materials has become a major issue related to the adjustment of the country's energy structure. . The synthetic gas phase methanol conversion technology from natural gas and coal has matured, which has laid a good foundation for the development of the methanol-to-olefin process. The methanol-to-propylene process will become anoth...

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Problems solved by technology

[0004] Reactor over-temperature often occurs during the feeding and commissioning process of the methanol-to-propylene unit. When the over-temperature is serious, there will also be a temperature runaway, which causes the catalyst bed temperature in the reactor to rise rapidly, seriously deviating from the design value, and affecting the reaction and equipment. will cause great harm

In order to reduce the impact of over-temperature and run-away temperature on the catalyst and reactor internals, it takes a long time to carry out the feeding operation under milder control conditions. The start-up feeding time of the reaction system needs at least 10-12 hours, and this The materials generated in the process need to be torched, which greatly increases the material consumption and energy consumption of the MTP device, resulting in huge economic losses

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