NOx recovery units
Nitrous gases or nitric fumes are hazardous emissions from many industries apart from the incineration of fossil fuels, such as nitration reactions, nitric acid production, or the thermal disposal of waste explosives. As NOx is a hazardous gas due to its acidic properties, environmental regulations usually limit its emission into the atmosphere.
Gases with a low NOx content, as they are generated during a combustion process, are mostly converted, by SCR or SNCR treatment methods with ammonia via catalyzed processes, into nitrogen and water. For higher NOx concentrations, the gases from nitration processes can be treated with a Bertrams NOx absorption system, with the benefit that NOx is recovered as valuable nitric acid. This treatment passes the NOx gases through highly efficient cooled aqueous absorption columns, where the aim is to remove or scrub the NOx from the waste gases and/or to produce nitric acid (HNO3) which can, after re-concentration, be recycled into the nitration process – enabling savings in expensive virgin nitric acid as a raw material. This technology requires no chemical consumption and normally uses only water and atmospheric air.