Rectification device and rectification process used for electronic grade sulfur hexafluoride production

Abstract

The invention relates to a rectification device and a rectification process used for electronic grade sulfur hexafluoride production. Specifically, a rough sulfur hexafluoride gas is pressurized and then sent into a precooler to be converted from gas to liquid under high pressure and low temperature conditions, then gasification, condensation and reflux are carried out in a first rectifying tower and a first condenser to remove high-boiling residue, and then by means of gasification, condensation and reflux in a second rectifying tower and a second condenser, the sulfur hexafluoride is condensed into a liquid state for collection, while low-boiling residue maintains a gas state and escapes from the second condenser. The rectification device and the rectification process provided by the invention can effectively remove high-boiling residue and low-boiling residue impurities from the rough sulfur hexafluoride gas, especially the hexafluoroethane and octafluoropropane impurity gases with a very close boiling point to sulfur hexafluoride under high pressure and low temperature states required by the rectification process. The obtained sulfur hexafluoride fully meets the technical requirements of electronic grade sulfur hexafluoride, also the equipment cost is low, and the production process is simple.

Description

technical field [0001] The invention relates to the technical field of sulfur hexafluoride production, in particular to a rectification device and a rectification process for the production of electronic-grade sulfur hexafluoride. Background technique [0002] Existing rectification units for the production of industrial-grade sulfur hexafluoride, such as figure 1 As shown, the device is mainly a rectification tower 2', the sulfur hexafluoride crude gas enters the precooler 1' after being pressurized by a membrane press, and is converted from a gaseous state to a liquid state under high pressure and low temperature, and then from a refined The middle part of the distillation tower 2' enters the tower still of the rectification tower 2'. In the tower kettle, the liquid sulfur hexafluoride absorbs heat and then gasifies. The gasified sulfur hexafluoride rises along the tower and exchanges heat with the liquid sulfur hexafluoride condensed in the tower top condenser 3′. The s...

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Problems solved by technology

[0003] The existing rectification device used for the production of industrial grade sulfur hexafluoride cannot produce electronic grade sulfur hexafluoride (that is, the gas sulfur hexafluoride used in the electronics industry) for the following reasons: the other two impurity components, hexafluoroethane, cannot be removed And octafluoropropane, because at normal temperature and pressure, the boiling point of hexafluoroethane is -78°C, the boiling point of octafluoropropane is -37°C, and the boiling point of sulfur hexafluoride is -63°C, and it is produced in sulfur hexafluoride The liquefaction temperature of hexafluoroethane is about 6°C lower than that of sulfur hexafluoride under the high pressure and low temperature state required by the middle rectification process, and the liquefaction temperature of octafluoropropane is about 5°C higher than that of sulfur hexafluoride, so most of the six Fluoroethane and octafluoropropane are left in the tower kettle together with sulfur hexafluoride

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