Method for producing nitric acid

Abstract

A process is described for producing nitric acid involving oxidizing ammonia gas to form dinitrogen tetroxide gas, reacting the dinitrogen tetroxide with water in an absorption zone to form aqueous nitric acid and nitric oxide gas, removing a nitric acid / nitric oxide stream from the absorption zone and feeding the stream into a nitric acid bleaching zone, removing impurities from the nitric acid in the bleaching zone to form nitric acid product and adding supplemental oxygen gas to one or more of the reaction streams to increase nitric acid production and or strength. The improvement involves injecting the supplemental oxygen into a nitric acid-containing process stream to form a gas bubble / liquid mixture in the stream, the mixture forming a fine dispersion of gas bubbles having diameters of less than about 0.1 mm. According to the invention, increased interfacial surface is created between the gas bubbles and the liquid mixture to facilitate removal of impurities from the liquid phase and shifting of the reaction.

Description

technical field

[0001] This invention relates to a process for the production of nitric acid, and more particularly to methods for removing impurities produced by the process, and for increasing nitric acid production or reducing supplemental oxygen requirements. Background technique

[0002] The industrial production of nitric acid is based on the ninety-year-old Ostwald method, which is subdivided into three main process steps:

[0003] I: ammonia oxidation

[0004] <chemistry num="001"> <chem file="99126938_cml001.xml" / > < / chemistry> (1)

[0005] II: Oxidation of Nitric Oxide and Dimerization of Nitrogen Dioxide

[0006] <chemistry num="002"> <chem file="99126938_cml002.xml" / > < / chemistry> (2)

[0007] <chemistry num="003"> <chem file="99126938_cml003.xml" / > < / chemistry> (3)

[0008] and

[0009] III: Absorption of dinitrogen tetroxide

[0010] ...

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