Propane dehydrogenation reaction product cascade refrigeration separation system and method

Abstract

The invention relates to a propane dehydrogenation reaction product cascade refrigeration separation system and a propane dehydrogenation reaction product cascade refrigeration separation method. The system comprises a cascade refrigeration cycle unit, a multi-stage cooling flash separation unit and a liquid product pressurized conveying unit which are sequentially coupled and connected, the multi-stage cooling flash separation unit realizes graded cooling separation of reaction products and gasification of raw material fresh propane through combination of a multi-stage heat exchanger and a multi-stage flash separator; the cascade refrigeration cycle unit provides different levels of cooling capacity requirements and corresponding heat requirements for the multi-level cooling flash separation unit; and the liquid product pressurized conveying unit converges, flashes, pressurizes and conveys the liquid product obtained by the multi-stage cooling flash separation unit. Through coupling of all the units, the separation process requirement of reaction products is met, reaction feeding is completely gasified, cooling capacity is fully utilized, the process is simple, unit product energy consumption is low, the reaction product recovery rate is high, product purity is high, starting and stopping can be rapidly conducted, and the adaptability of the device to different working conditions and product scales is enhanced.

Description

technical field [0001] The invention relates to the technical field of cryogenic separation of hydrogen-rich light hydrocarbon mixtures, in particular to a cascade refrigeration separation system and method for propane dehydrogenation reaction products. Background technique [0002] Propylene is a kind of low-carbon olefin. Because of its double bond in the molecule and active chemical properties, it can react with many substances such as addition, copolymerization or self-polymerization to generate a series of important products, which are mainly used for the production of polypropylene, cyclic Oxypropane, acrylic acid, acrylonitrile, etc. Therefore, propylene is an important petrochemical basic raw material. Propane dehydrogenation technology is an important source of propylene. [0003] Propane dehydrogenation technology uses propane as raw material and obtains propylene through catalytic dehydrogenation. The propane dehydrogenation reaction product is dominated by hydr...

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Problems solved by technology

[0005] Expansion refrigeration is a refrigeration method often used in the separation system of propane dehydrogenation reaction products. Expansion refrigeration has high requirements on the boundary pressure of the reaction product entering the separation system, and cannot adapt to the separation requirements of the wide-range fluctuation of hydrogen content in the reaction joint feed. , especially, as the hydrogen content in the combined reaction feed decreases and the pressure of the reaction product entering the separation system gradually decreases, the self-expansion refrigeration of the reaction product cannot provide enough cooling capacity to meet the process separation requirements of the reaction product separation system, which eventually leads to The separated hydrogen-rich gas contains high C3 content and low hydrogen purity, which reduces the recovery rate of C3 products, increases the separation load of PSA, and reduces the overall economic efficiency of the device.

In addition, the expander must adopt a corresponding braking method such as a generator or a supercharger. The equipment rotates at a high speed, the system investment and matching are complicated, and it is prone to the risk that the gas at the inlet of the expander will be damaged and the whole unit will be damaged and unable to operate, resulting in large Economic losses

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