Large-scale energy-saving gradient air separation process

Abstract

The invention provides a large-scale energy-saving gradient air separation process. Pressurized air which is dried and removed from carbon dioxide previously is subjected to adsorption separation by aradial zeolite molecular sieve pressure-swing absorber, causing the nitrogen to be adsorbed by the zeolite molecular sieve and 50%-85% of oxygen-enriched air to flow out of the zeolite molecular sieve pressure-swing absorber. The zeolite molecular sieve pressure-swing absorber is switched by a sequencing valve to deliver or discharge the high-purity nitrogen as a product after reduced pressure desorption thereof, and the zeolite molecular sieve pressure-swing absorber is reused. The oxygen-enriched air flowing out of the zeolite molecular sieve pressure-swing absorber is subjected to adsorption separation in a carbon molecular sieve pressure-swing absorber, causing the oxygen to be absorbed by the carbon molecular sieve and the residual nitrogen, argon, helium and the like to be discharged out of the carbon molecular sieve pressure-swing absorber; the carbon molecular sieve pressure-swing absorber is switched by the sequencing valve to discharge the high-purity oxygen as a product after reduced pressure desorption thereof, and the carbon molecular sieve pressure-swing absorber is reused.

Description

[0001] 1. Technical field [0002] The invention provides a large-scale energy-saving cascade air separation process, which belongs to the technical field of air separation. [0003] 2. Background technology [0004] The production of modern coal chemical industry, metallurgical industry, petroleum refining and sulfuric acid industry needs to consume a lot of oxygen, but the demand for nitrogen is small. Among the existing oxygen production methods, the air separation method is the most economical industrial oxygen production method. At present, in the field of air separation, cryogenic rectification (cryogenic separation) is a traditional oxygen production method, and pressure swing adsorption and membrane separation are emerging oxygen production methods. The cryogenic rectification method is mature, suitable for large-scale production of high-pressure oxygen and high-pressure nitrogen, can obtain high-purity oxygen and nitrogen, and has a high recovery rate, but the product...

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Problems solved by technology

[0005] However, for the production processes such as coal oxygen-enriched combustion, semi-coke oxythermal method to produce acetylene, metal oxythermal reduction smelting, heavy oil pyrolysis gasification coupling, and sulfuric acid industry, a large amount of low-pressure oxygen is consumed, while the demand for nitrogen is small. The investment and energy consumption of cryogenic separation is too large and the potential energy of oxygen pressure is lost. It is urgent to develop large-scale pressure swing adsorption air separation technology and equipment to meet the modern industry's demand for low-pressure high-purity oxygen.

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