Process and apparatus for purification of chlorine gas contaminated with bromine

• Main Authors: OTAL, JOSE VICENTE, BENKAHLA, BEN AISSA, DIETRICH, MARC, HERNANDEZ, JOSE LUIS
• Format: Patent
• Language: English; French; German
• Published: 16.02.2000
• Edition: 7
• Subjects: CHEMISTRY; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING

The flow of chlorine gas is washed in a column (5) with an aqueous solution comprising a low-salt brine extracted from downstream of electrolyzers (3) producing chlorine by electrolysis of brine. The brine washing is carried out in back flow, preferably with the chlorine gas flowing upwards, at a temperature of between 10 and 35 degrees C, and preferably between 15 and 20 degrees C. In addition, downstream of the washing process, the bromine and chlorine are separated from the brine by stripping using water vapor under vacuum or with a gas, preferably air. The process is operated on the site of chlorine production by electrolysis. The low-salt brine is cooled before washing the chlorine. The heat from the cooling process is used to carry out the stripping process. After stripping, the low-salt brine is recycled to upstream of the electrolysis units. At least one purge is put into this recycling line. An Independent claim is also included for the device for carrying out this process, comprising a unit producing chlorine by electrolysis of brine, a washing column for the gaseous chlorine, and a circuit carrying a fraction of the low-salt brine, taken from downstream of the electrolyzers (3) to the washing column (5). The device also contains a stripping unit (7) for removing chlorine and bromine from the brine after the washing process. A heat exchanger (E1) cools the brine before it enters the column and warms the brine leaving the column before it enters the stripper. La présente invention a pour objet un procédé et un dispositif de purification de chlore gazeux pollué par du brome. Ledit procédé comprend le lavage dudit chlore gazeux avec une solution aqueuse. De façon caractéristique, ledit lavage est mis en oeuvre, avantageusement à contre-courant, avec, à titre de solution aqueuse, de la saumure appauvrie en sel, prélevée en aval des électrolyseurs d'une unité de production de chlore par électrolyse d'une saumure.