Preparation by absorption of oxides of nitrogen (C01B21/40)

Method of producing nitric acid (versions) and plant to this end

Invention relates to nitric acid production and may be used in chemical industry. Compressed air is fed into one stage of gas turbine unit. Portion of compressed flow is cooled down and directed for cooling recuperative turbine 10. Major airflow is cooled in plate-type heat exchanger in feeding heated water to recovery boiler 6 and/or in steam generator while produced steam is directed for evaporation of liquid ammonia and/or heating and deaerating chemical cleaned water. Major flow is divided into two flows. First flow is fed to mixing with heated gaseous ammonia while second flow is fed into vent column16. Ammonia is oxidised by air of first flow at catalyst. Nitrose gas is cooled in recovery boiler 6 with bypass adjustment of its feed for heating end gases in two stages. Nitrose gas is aftercooled by water to condense reaction moisture in two stages. Nitrose gas is absorbed by steam condensate or desalted water. Nitric acid is blown by second pre-cooled airflow and divided into two flow, one to be fed for nitrose gas oxidation and second one to be fed into vent column 16. End gases are heated, cleaned of nitrogen oxides at catalyst, heated in gar turbine combustion chamber 19 to recover energy of off-gases in recuperative turbine 10.

Apparatus for producing nitric acid

Invention relates to inorganic chemistry and apparatus for producing nitric acid. The apparatus for producing nitric acid has pipes for supplying nitrogen and oxygen, a gas mixer 3, a generator 7 with gas inlet 8 and outlet 9 nozzles, a gas-water mixer 11 and a heat exchanger 12. The gas mixer 3 and the generator 7, in which a high-temperature zone with a gas phase is formed by creating nanosecond cold plasma electric arc streamer discharges, form a generator unit 1. The gas-water mixer 11, heat exchanger 12, which is a cooler and circulating pump 15 form an absorption unit 2, which is in form of a circulation loop. The absorption unit 2 also includes a surge vessel 13 in which there is a concentrator 14, which serves to maintain balance of the working solution.

Method of the non-concentrated nitric acid production

The invention is pertaining to the method of production of the nitric acid and may be used in chemical industry in the power-engineering operational layouts of production of the nitric acid containing the recuperation and high-temperature gas-turbine aggregate with application of the low-temperature catalytic selective purification of the exhaust gases from nitrogen oxides. The method of production of the non-concentrated nitric acid includes production of the nitrogen oxides by ammonia oxidizing, their absorption by the water, the catalytic purification of the exhaust gases after absorption by recovery of the residual nitrogen oxides by ammonia, their heating before feeding into the gaseous turbine by interaction of the methane with the oxygen on the catalytic agent ensuring decomposition of the nitrous oxide till the residual content of 5÷60ppm. As the catalytic agent use the high-temperature manganese -alumina catalytic agent with the contents of the active component - Mn2О3 ≥ 10 mass % on the A12O3 carrier at the volumetric speed of the flow of 15000-25000 hour-1. The oxygen content in the exhaust gases after the absorption is maintained within the range of 2.9-3.5 volumetric %, the volumetric ratio of СН4/O2 at the inlet of the reactor is within the range 0.37 - 0.48. The method ensures the high level of the ecological purity of the exhaust gases, reduces the consumption of the natural gas used for heating up of the purified exhaust gases up to the temperature of no less than 730°С.

Method of intensification of the installation for production of nitric acid

The invention is pertaining to the method of intensification of the installations for production of the non-concentrated nitric acid and may be used for raising productivity of the installations for production of the non-concentrated nitric acid under pressure. The invention provides for creation of the excess pressure on the inlet of the air compressor by preliminary compression of the atmospheric air in the high-pressure fan. At that the heat of the compression process in the warm season of the year is withdrawn by the direct contact with the water at the inlet of the fan, and in the cold season the heat is used for heating, at that in full or partially excluding heating of the air in the preheater mounted to prevent the icing up of the guiding apparatuses of the air compressor. At the enterprises with the high degree of the air dusting or chemical pollution for the contact cooling of the air by water it is possible to use scrubbers-washers, which combine the functions of the air cooler and the purification device. The method is effective for the operating installations, in which as a result of the wear-out of the flow-through section of the air compressors and the gas turbines decreases not only productivity, but also the pressure in the system, and as the result of it the concentration of the nitric acid. The method allows to realize the intensification of the installations using already existed equipment due to the increased pressure in the system. Concentration of the nitric acid is not lowered, the degree of purification of the tailing gases is preserved, production cost and the specific consumption of the steam and the natural gas are reduced.

Method of removing no_x and n₂o from nitric acid production residual gas

Invention aims at reducing concentration of NOx and N2O in residual gas and provides a method wherein residual gas escaping absorption column, prior to enter turbine, is passed through two consecutive steps first reducing NOx content by catalytic reduction and then reducing N2O content by decomposing it into nitrogen and oxygen on catalyst containing one or more iron-loaded zeolites at working pressure 4-12 bar. Molar ratio NOx/N2O in residual gas before second step lies within a range of 0.001 to 0.5.

Method of modernization of an installation for production of nitric acid with its increased productivity

The invention is pertaining to the field of chemical industry, in particular, to the method of modernization of installations of nitric acid production. The method of modernizing of installation of production of the nitric acid providing for oxidation of ammonia with the help of air under a rarefaction, compression of the cooled nitrous gases in a nitrose supercharger, an absorption of nitric oxides in a tower absorber under pressure of 3.5-4.0 kg / cm2, expansion of the waste tail gases in the turbo-expander, consists in the fact that they increase the pressure of the nitrous gases at the inlet of the supercharger in the range from rarefaction up to the pressure of 1.02-1.05 kg / cm2, by installing a new or an additional gas blowers on the lines of the ammonia - air mixture or the nitrous gases or by decrease of hydraulic resistance of apparatuses and devices of pipelines at absorption inlet of the nitrose supercharger. At a pressure increase at the inlet of absorption of the nitrose gasses supercharger by decrease of the hydraulic resistance of the apparatuses and pipelines before absorption of the nitrose supercharger the increase of productivity of the installation will be much lower (~ up to 8 %). The method ensures an increase of productivity of the installation using the existing equipment at addition of small investments, which pay off less than for 1 year (from 0.6 up to 0.8 of a year) due to decrease of specific consumptions of raw material and power and a significant decrease of the conditionally-permanent expenses. Simultaneously the method allows to increase concentration of nitric acid and a degree of absorption, that may achieve its maximum at addition of pressure systems.

Method for production of nitric acid

Claimed method includes ammonia catalyst oxidation and nitrogen oxides absorption from nitrous gas with water and nitric acid, wherein nitrogen oxides absorption in absorption unit is carried out by using mass-exchange elements having several absorbing zones with different surfaces. Ratio (n) of oxidized nitrogen monoxide (NO) and absorbed nitrogen dioxide (NO2) in determined according to equation: lg n = (0.22-0.29)-0.0626 lg PNOx, wherein PNOx is partial pressure of nitrogen oxides in nitrous gas. According the invention it is made possible to increase absorption ratio and reduce nitrogen oxide content in exhaust gas up to 0.005 vol.%.

Method of nitric acid production and an installation for production of nitric acid

The invention is dealt with production of nitric acid with the help of oxidation of ammonia by oxygen of the air and absorption of nitrogen oxides by water in installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides. The method of production of nitric acid in the installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides provides, that compression of the air up to a uniform terminal pressure is conducted continuously within one stage without intermediate cooling and after that the compressed and so heated air is divided into two streams, one of which intended for production of nitric acid is directed to be cooled with further mixing with ammonia, and another is fed directly into a fuel combustion chamber connected with a recuperation turbine. The design embodiment of the installation for production of nitric acid provides for usage in the gas-turbine plant as an air engine for compression of air of an axial-flow compressor mounted directly on a common shaft with the recuperation turbine, at which near the outlet of the air engine the line of a compressed air stream is divided into two parts, one of which intended for production of nitric acid is first connected with a compressed air cooler and then with a mixer of ammonia with air, and the second intended for incineration of fuel is directly connected with the recuperation turbine combustion chamber. Besides in the capacity of a the compressed air cooler they use a "boiling" economizer connected to a line of a feed water for a boiler-utilizer and with a vapor collector of the boiler-utilizer by a line of steam-and-water mixture. The line of the air intended for production of nitric acid is also connected through the reheater of ammonia with a nitric acid blowing column. The technical result is simplification of the method, decreased investments and specific consumption of fuel.