A method for separation and recovery of nitrogen in high-temperature tail gas

Abstract

The invention discloses a method for separating and recovering nitrogen in high-temperature tail gas, which comprises: a. detecting the nitrogen content in high-temperature tail gas. b1 transports the high-nitrogen tail gas with a nitrogen content of more than 90% to the first molecular sieve membrane bed. The first molecular sieve membrane bed absorbs nitrogen in the high-nitrogen tail gas and separates gases other than nitrogen in the high-nitrogen tail gas. b2 sends the low-nitrogen tail gas with a nitrogen content of less than 90% to the second molecular sieve membrane bed to absorb carbon dioxide in the low-nitrogen tail gas. c. Pressurize and lower the temperature of the second gas passing through the second molecular sieve membrane bed, send it to the rectification tower for rectification, and obtain purified nitrogen according to the difference in boiling point between nitrogen and oxygen. Among them, zeolite molecular sieve is selected for the first molecular sieve membrane bed, and 3A molecular sieve is selected for the second molecular sieve membrane bed.

Description

technical field [0001] The invention belongs to the field of tail gas treatment and recovery, and in particular relates to an economical and environment-friendly method for separating and recycling high-temperature furnace tail gas, especially for high-temperature furnace nitrogen-containing tail gas. Background technique [0002] At present, the purification of raw material graphite in synthetic diamond enterprises at home and abroad is produced by dry process. Most of the equipment used is high-temperature furnace, and the working temperature in the furnace is generally above 2800°C. Due to the poor oxidation resistance of graphite, especially at high temperature, it is easier to oxidize to carbon dioxide. Volatile, so the purification of graphite at high temperature must be carried out in an environment of anaerobic and inert gas (such as nitrogen, argon, etc.) to ensure a higher yield and recovery of graphite. But in fact, due to the change of raw materials and processes...

AI Technical Summary

Problems solved by technology

But in fact, due to the change of raw materials and processes and the poor sealing effect of the valves on the furnace, the composition of the exhaust gas discharged from the high-temperature furnace is relatively complex. The exhaust gas of the high-temperature furnace includes not only inert gases, but also oxygen or carbon oxides, etc. impurity gas

Therefore, when recycling graphite products, it is also necessary to consider how to deal with inert gases and impurity gases. If the inert gases and impurity gases are directly discharged into the air, it will pollute the environment.