US 6,969,446 B1Granted

Method for producing concentrated nitric acid and installation for carrying out a method of this type

AssigneeQVF Engineering GmbH

InventorsGottfried Dichtl, Frank Dorstewitz, Manfred Sassenberg, Ulrich Walter

Life of this patent

Estimating the term…

Loading patent…

Abstract

Process for producing a nitric acid of a concentration from 75 to 99.9% from a more diluted nitric acid, wherein a nitric acid of a concentration of about 45 to 70% is rectified in contact with a liquid extraction medium to prevent the formation of a nitric acid-water-azeotropic mixture, and the vapors of the concentrated nitric acid are condensed and a concentrated nitric acid is obtained and wherein additionally the extraction medium is reconstituted through reconcentration and returned into the extractive rectification, wherein the nitric acid to be concentrated is fed as a boiling liquid or partially vaporized to the extractive rectification preferably carried out in two columns (K 1.0, K 1.1), by utilizing the amounts of heat available to the entire process (W1, W2, W5), wherein, before feeding into the extractive rectification nitric acid is added to the extraction medium, and the energy required for the extractive rectification is supplied through indirect heating (W4, W8) and the extraction medium supplied in most concentrated form to the extractive rectification, so that simultaneously at the greatest possible dilution of the extraction medium flowing from the extractive rectification, the circulation amount of extraction medium is minimized and the utilization of energy maximized.

A process for the production of a nitric acid with a concentration of 75 to 99.9% from a more diluted or an impure starting nitric acid, comprising the steps of:

contacting a starting nitric with an amount of extractive medium for rectification by feeding the nitric acid of a concentration of about 45 to 70% in a form selected from the group consisting of boiling liquid and in partially vaporized state or separated into vapor and liquid, into an extractive rectification under pressure condition selected from the group consisting of atmospheric pressure, hyperbaric pressure and vacuum and under prevention of forming a nitric acid and water azeotrope,
obtaining nitric acid vapors from the rectification step and condensing the vapors to thereby obtain a concentrated nitric acid,
reconstituting the extractive medium by reconcentration and returning the extractive medium to the extractive rectification,
enriching at least 50% of the amount of extractive medium with nitric acid in an amount of 0.1 to 60% of the starting nitric acid before feeding it into the extractive rectification, and
supplying the extractive medium in high concentration to the extractive rectification, while at the same time as the extractive medium, which is in a condition of low concentration, is flowing from the extractive rectification, a circulation amount of extractive medium is minimized, and wherein energy required for the extractive rectification heating is supplied through indirect heating from available process streams of the entire process, wherein the extractive rectification is carried out in two columns separated by an input site for the starting nitric acid, or in a concentration column which is divided into two column portions, wherein the rectification of the starting nitric acid and the yield of the concentrated nitric acid vapor is carried out in a first one of the two columns, and a separation of the nitric acid from the extractive medium is carried out in a second one of the two columns.

2 more elements

Abstract

Claims25