Method and apparatus for producing nitrogen trifluoride

Abstract

The invention provides a method and apparatus for producing nitrogen trifluoride. The invention involves passing a working fluid through a heat engine cycle and using the mechanical energy generated by the working fluid to produce sufficient mixing intensity within a nitrogen trifluoride reactor. The method utilizes a working fluid vapor jet, such as a hydrogen fluoride vapor jet, to impart sufficient energy to the mixing zone of a reactor in order to disperse gaseous fluorine within a liquid ammonium acid fluoride melt. A gaseous reaction product stream is removed from the reactor, the reaction product stream comprising nitrogen trifluoride and a working fluid vapor. The working fluid is then separated from the nitrogen trifluoride and recycled for reuse in the process, thereby completing a heat engine cycle.

Description

technical field [0001] The present invention relates to a method and device for producing nitrogen trifluoride from ammonia and elemental fluorine by utilizing ammonium bifluoride melt intermediate. Background technique [0002] Nitrogen trifluoride can be produced by the gas-phase reaction of ammonia and gaseous elemental fluorine. Reaction 1 illustrates the preparation of NF 3 desired gas-phase reaction. [0003] <chemistry num="001"> <chem file="03120687_cml001.xml" / > < / chemistry> (?H = -904 kJ / gmol NF 3 ) [0004] Response 1 [0005] where (g) represents the gas phase. Usually solid catalysts are used to lower the desired reaction temperature and increase NF 3 yield. However, due to the highly exothermic nature of Reaction 1, controlling the temperature of the reactor is very difficult. As a result, gas-phase ammonia and fluorine react to produce large amounts of HF, N 2 , N 2 F 2 and NH 4 F, while NF 3 T...

AI Technical Summary

Problems solved by technology

However, the high power input suggested in the Coronell patent generates high shear rates which will remove the passivation layer and expose the underlying turbine substrate to fluorine, thereby accelerating corrosion, especially at the tip of the mixing impeller

Corrosion therefore causes excessive vibration of the mixer shaft and premature failure of the mixer shaft seal

Even with very frequent maintenance in operation, essentially preventing vibration of the shaft, the combination of high-speed rotating seals and corrosive fluorine and hydrogen fluoride atmospheres will cause reliability problems

Additionally, the high mechanical energy input into the reactor via the flat-bladed turbine can lead to a high degree of back mixing of the reaction volume under substantially uniform operating conditions

In this case there is no opportunity to optimize the local reactor operating conditions

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