Closed relay purging process for stable absorption and desulfurization unit shutdown of catalytic cracking unit

Abstract

The present invention provides a catalytic cracking apparatus stable absorption unit and desulfurization unit shutdown sealed relaying purging process. According to the present invention, during the catalytic cracking apparatus shutdown process, the sealed relaying purging technology of various towers in the stable absorption unit and the desulfurization unit is performed, the stable absorption unit purging steam is purged to the desulfurization unit, and through various tower top safety valve sub-pipelines of the desulfurization unit, the steam purging oil gas is conveyed to the low pressure flare pipeline inside the apparatus and is transferred into a fractionation tower, is cooled through a fractionation tower top cooling system, and is separated in an oil-gas separator in front of a gas compressor. According to the present invention, the low pressure flare pipeline to the outside of the apparatus is added to the oil-gas separator to discharge the non-condensing gas to the gas cabinet outside the apparatus and recover, such that the sealed relaying purging of the stable absorption unit and the desulfurization unit of the cracking apparatus is achieved through the simple process change in the case of no increase of the additional cooling equipment investment so as to achieve the environmental protection shutdown purpose.

Description

technical field [0001] The invention relates to a kind of catalytic cracking device, during the shutdown process of a stable absorption unit and a desulfurization unit, each tower is closed and relay purging process. Background technique [0002] The heavy oil catalytic cracking unit adopts the MIP-CGP process, and the design capacity is 800,000 tons / year. During the maintenance and shutdown process of the catalytic cracking unit over the years, the absorption tower, desorption tower, reabsorption tower and desulfurization unit in the stable absorption unit have no cooling system at the top of each tower, resulting in the fact that the purge steam of each tower cannot be condensed during the shutdown process, and the steam blowing Sweeping oil and gas must not enter the low-pressure flare system, resulting in shutdown steam purging, must be vented by opening the top of the tower. Cause environmental pollution, and oil and gas loss. Nowadays, due to the increasing pressure ...

AI Technical Summary

Problems solved by technology

[0003] Aiming at the problem that the purge steam of each tower cannot be condensed during the shutdown process of the existing catalytic cracking unit, and must be discharged from the top of the tower, causing environmental pollution and oil and gas loss, the present invention provides a catalytic cracking unit shutdown process. Sealed relay purging process realizes environmental shutdown of catalytic cracking unit and recovery of oil and gas

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