System and method for recovering VOCs at top of tank and reusing nitrogen gas

Abstract

The invention discloses a system and a method for recovering VOCs at the top of a tank and reusing nitrogen gas. The system comprises a pressurization subsystem, a condensation subsystem, a pressure swing adsorption subsystem and a nitrogen recovery subsystem, wherein the pressurization subsystem comprises a pressurization air pump and a flame arrester; the condensation subsystem comprises a regenerative heat exchanger, a precooling heat exchanger, a shallow cooling heat exchanger, a cryogenic heat exchanger, an explosion-proof refrigeration compressor, a condensation heat exchanger, an evaporation condensation heat exchanger, a throttling element and the like; the pressure swing adsorption subsystem comprises more than two groups of pressure swing adsorption devices which are arranged inparallel; and the nitrogen recovery subsystem comprises a nitrogen buffer tank and a one-way valve. According to the invention, the pressure regenerative heat exchanger, the precooling heat exchanger,the shallow cooling heat exchanger and the cryogenic heat exchanger are used for gradual cooling condensation, pressure swing adsorption recovery and purification of the VOCs gas at the top of the tank, and finally the VOCs are recycled; the nitrogen at the top of the tank is reused after purification; and the unit does not have any secondary pollution during operation.

Description

Technical field [0001] The present invention relates to a tank top VOCs recovery and inert gas reuse system and method, in particular to a nitrogen sealing tank top gas recovery and nitrogen reuse system and method. Background technique [0002] In oil refining and petrochemical plants, various oil or petrochemical products are stored. Most storage tanks are built outdoors. In order to avoid direct contact of these materials with air, prevent the materials from volatilization and oxidation, and the safety of the container, nitrogen sealing devices are often used to keep the pressure of nitrogen on the top of the container constant and isolate it from the outside world. In addition, in order to reduce the loss of material volatilization caused by small breathing and large breathing during storage of the tank, a nitrogen sealing device is also used. [0003] The treatment of VOCs waste gas from the tank roof is fully carried out under the pressure of safe production and environmenta...

AI Technical Summary

Problems solved by technology

Chinese patent CN201721880896.2 discloses a device for recovering and utilizing VOCs gas discharged from a fixed-roof storage tank. The device uses a combination of alkali cleaning unit, recovery unit and fuel gas pipeline network to s...

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