Deep-cooling pressure-swing double-effect separation system in propylene production process

Abstract

The invention discloses a deep-cooling pressure-swing double-effect separation system in a propylene production process. The system includes a first stripping column, a heat exchanger, a second flashing tank and a second stripping column, and is characterized in that: the bottom of the first stripping column is connected to the heat exchanger through a pipeline; the heat exchanger is respectivelyconnected with the second flashing tank and the second stripping column; the left bottom of the heat exchanger is connected with the middle section of the second stripping column via a pipeline; the right bottom of the heat exchanger is connected with the middle section of the second flashing tank through a pipeline; the bottom of the second flashing tank is connected to the top of the second stripping column via a pipeline; the top of the second stripping column is connected to the right upper part of the heat exchanger via a pipeline; and the upper part of the heat exchanger is connected tothe first column bottom arranged at the bottom of the first stripping column. The system has the advantages that the using amount of cooling utility is small, the utilization efficiency of each lightcomponent gas resource is significantly improved, the operating load is significantly decreased, the system energy consumption index is relatively low, and the internal coupling efficiency of the system process is obviously high, which can effectively improve the economic benefit of a project.

Description

technical field [0001] The invention relates to the technical field of cryogenic separation process in propylene production, in particular to a cryogenic pressure-swing double-effect separation system in propylene production process. Background technique [0002] Select liquefied petroleum gas, which is rich in production in the petrochemical process, with low economic added value and low resource utilization efficiency, as raw material, and produce propylene products with a large gap in the market and high economic added value, which can broaden the petrochemical industry chain and improve refining There are many significant advantages such as the economic benefits of the project and the market competitiveness of the enterprise. The main process flow is as follows: firstly, the liquefied petroleum gas (more than 96.9% propane) passes through the pretreatment unit to remove pollutants and water in the raw material, and the obtained fresh propane is mixed with the circulating...

AI Technical Summary

Problems solved by technology

First, the crude propylene from the oxidation unit undergoes cooling, crude dehydration and fine dehydration in sequence, then cools down and removes all the water in the crude propylene, cools the components to be separated to about -55°C, and conducts them in the double-column direct sequence separation system. Separation, light components are collected from the top of the pre-separation tower, and CO is collected from the top of the main separation tower 2 , Propylene and propane are extracted from the bottom of the tower and sent to the propylene refining unit. The operating temperature difference between the pre-separation tower and the main separation tower is -95°C, and the air pressure difference is 1.4Mpa. , if the momentum is provided by power equipment, the power consumption will increase significantly, the energy consumption index of the project will be high, and the overall economic benefits will not be high

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