System and method for separating and recycling propylene in epoxypropane production process with HPPO (Hydrogen Peroxide Direct Oxidation Process) method

Abstract

The invention provides a system and a method for separating and recycling propylene in the epoxypropane production process with an HPPO (Hydrogen Peroxide Direct Oxidation Process) method. The systemcomprises a distillation tower, a pre-separation tower, a subcooler and a compressor which are connected in sequence. By adopting the system and the method, a propylene separation process used in thepropylene epoxide production process is improved, equipment is simplified and reconnected, conveying flows of the compressor are reduced, the feeding state of propylene is changed, then the operationburden of the compressor is reduced, normal operation of the system is ensured, meanwhile a relatively good separation effect is achieved, and as the equipment and the process are simplified, equipment investment is reduced, and the process technique is relatively good in economic property.

Description

technical field [0001] The invention belongs to the technical field of separation of chemical products, and relates to a separation and recovery system and method for propylene in the process of producing propylene oxide by an HPPO method. Background technique [0002] Propylene oxide is an important chemical raw material. It is the third largest organic chemical product in the output of propylene derivatives after polypropylene and acrylonitrile. It is widely used in chemical, pharmaceutical, food and textile industries. The traditional industrial production methods of propylene oxide mainly include the chlorohydrin method and the co-oxidation method. The chlorohydrin method has a mature production process and does not require high purity of raw material propylene, but a large amount of waste water and waste residue will be generated during the production process. With the environmental situation However, the co-oxidation method overcomes the shortcomings of the chlorohydri...

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Problems solved by technology

CN 1256274 A discloses a process flow for continuous production of propylene oxide by oxidizing propylene with hydrogen peroxide. It adopts a slurry stirring reactor. When carrying out epoxidation reaction, the reaction pressure is low, the temperature is easy to control, and the conversion rate of raw materials and product yield Higher, but there are still many subsequent separation equipment in this process, the process is complicated, and the energy consumption is high

[0004] In the production process of propylene oxide by HPPO method, the separation of propylene is an indispensable operation unit. The conventional process is to first pass through the rectification tower, then pass through the two-stage flash tank, and finally separate again in the pre-separation tower, and the two-stage flash evaporation The top of the tank is equipped with a propylene compressor. Due to the large amount of gas contained in the top of the flash tank, the operating load of the compressor is large, the power consumption is large, and the inlet medium is saturated gas, which is easy to condense into liquid at the inlet of the compressor, which affects the compression. The machine is in normal operation; at the same time, the process flow of the separation unit is complicated, there are many equipments, and the investment is relatively large

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