A process for preparing nitric acid may involve vaporizing ammonia in at least one first ammonia vaporizer to produce an ammonia gas, oxidizing this ammonia gas to nitrogen dioxide in a plant section of a nitric acid plant, and absorbing the nitrogen dioxide in water to produce nitric acid. A residual gas containing nitrous gases may be taken off from the plant section of the nitric acid plant and conveyed to a residual-gas cleaning apparatus. The residual gas containing nitrous gases may be reduced by means of ammonia in the residual-gas cleaning apparatus, wherein ammonia-containing wastewater obtained in the at least one first ammonia vaporizer may be conveyed to the residual-gas cleaning apparatus. Such a process may eliminate or at least substantially reduce ammonia-containing wastewater. Furthermore, a plant can be used in this process for preparing nitric acid.

A process for preparing nitric acid may involve vaporizing ammonia in at least one first ammonia vaporizer to produce an ammonia gas, oxidizing this ammonia gas to nitrogen dioxide in a plant section of a nitric acid plant, and absorbing the nitrogen dioxide in water to produce nitric acid. A residual gas containing nitrous gases may be taken off from the plant section of the nitric acid plant and conveyed to a residual-gas cleaning apparatus. The residual gas containing nitrous gases may be reduced by means of ammonia in the residual-gas cleaning apparatus, wherein ammonia-containing wastewater obtained in the at least one first ammonia vaporizer may be conveyed to the residual-gas cleaning apparatus. Such a process may eliminate or at least substantially reduce ammonia-containing wastewater. Furthermore, a plant can be used in this process for preparing nitric acid.

A high-concentration ammonia production method includes: synthesizing ammonia through electrolysis using water and nitrogen as raw materials; subjecting a resultant generation gas to treatment using an ammonia separation membrane or an ammonia PSA to separate the generation gas into high-concentration ammonia and a residual gas; recycling the residual gas as a nitrogen gas raw material of an ammonia synthesis reactor, and liquefying the high-concentration ammonia recovered through the ammonia separation membrane or the ammonia PSA; and subjecting an unliquefied gas separated from liquefied ammonia to the treatment using the ammonia separation membrane or the ammonia PSA again. According to the present disclosure, ammonia is synthesized by adopting an electrolysis method in which the synthesized ammonia substantially does not contain hydrogen, in combination with ammonia separation and recovery treatment using membrane separation or PSA. With this, high-concentration ammonia can be synthesized and recovered with high efficiency through an entire process.

A high-concentration ammonia production method includes: synthesizing ammonia through electrolysis using water and nitrogen as raw materials; subjecting a resultant generation gas to treatment using an ammonia separation membrane or an ammonia PSA to separate the generation gas into high-concentration ammonia and a residual gas; recycling the residual gas as a nitrogen gas raw material of an ammonia synthesis reactor, and liquefying the high-concentration ammonia recovered through the ammonia separation membrane or the ammonia PSA; and subjecting an unliquefied gas separated from liquefied ammonia to the treatment using the ammonia separation membrane or the ammonia PSA again. According to the present disclosure, ammonia is synthesized by adopting an electrolysis method in which the synthesized ammonia substantially does not contain hydrogen, in combination with ammonia separation and recovery treatment using membrane separation or PSA. With this, high-concentration ammonia can be synthesized and recovered with high efficiency through an entire process.

An ammonia-containing liquid or an ammonia-containing gas is made to contact a porous coordination polymer in which a metal ion and an organic ligand coordinately bonded, ammonia is adsorbed to the porous coordination polymer, and the ammonia is desorbed from the ammonia-adsorbed porous coordination polymer to recover the ammonia. The porous coordination polymer that contacts the ammonia-containing liquid preferably has a water-soluble solvent adhered thereto. The ammonia-containing gas is preferably adjusted such that water is contained at an amount of 106 parts by mass or more when the ammonia content is 100 parts by mass.

An ammonia-containing liquid or an ammonia-containing gas is made to contact a porous coordination polymer in which a metal ion and an organic ligand coordinately bonded, ammonia is adsorbed to the porous coordination polymer, and the ammonia is desorbed from the ammonia-adsorbed porous coordination polymer to recover the ammonia. The porous coordination polymer that contacts the ammonia-containing liquid preferably has a water-soluble solvent adhered thereto. The ammonia-containing gas is preferably adjusted such that water is contained at an amount of 106 parts by mass or more when the ammonia content is 100 parts by mass.

The present invention relates to processes and systems for ammonia recovery and/or acid-gas separation. In some embodiments, a system for acid gas separation may be integrated with an ammonia abatement cycle employing a high temperature absorber. In some embodiments, a system for acid gas separation may employ a higher temperature absorber due to the lower energy consumption and cost of the integrated ammonia abatement cycle. Advantageously, heat may be recovered from the absorber to power at least a portion of any acid gas desorption in the process. Reverse osmosis or other membranes may be employed.

The present invention relates to processes and systems for ammonia recovery and/or acid-gas separation. In some embodiments, a system for acid gas separation may be integrated with an ammonia abatement cycle employing a high temperature absorber. In some embodiments, a system for acid gas separation may employ a higher temperature absorber due to the lower energy consumption and cost of the integrated ammonia abatement cycle. Advantageously, heat may be recovered from the absorber to power at least a portion of any acid gas desorption in the process. Reverse osmosis or other membranes may be employed.

Systems and methods for enhanced separation of H2S and NH3 in an H2S stripper using carbon dioxide and/or an inert gas.

Systems and methods for enhanced separation of H2S and NH3 in an H2S stripper using carbon dioxide and/or an inert gas.