Method for production of nitric acid
 Method of nitric acid production and an installation for production of nitric acid / 2248322The 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. |
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Method of nitric acid production and an installation for production of nitric acid / 2248322 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. |
 Method for production of nitric acid / 2248936Claimed 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 modernization of an installation for production of nitric acid with its increased productivity / 2253614The 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 of removing nox and n2o from nitric acid production residual gas / 2259227Invention 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 intensification of the installation for production of nitric acid / 2286943The 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. |
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Method of the non-concentrated nitric acid production / 2296706 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. |
 Apparatus for producing nitric acid / 2415806Invention 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 producing nitric acid (versions) and plant to this end / 2470856Invention 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. |
FIELD: mineral acid manufacturing, in particular method for production of 50-70 % nitric acid from nitrous gas.
SUBSTANCE: 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.%.
EFFECT: environmental friendly method with improved nitrogen oxide absorption.
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The present invention relates to the production of mineral acids, in particular to methods for 50-70% of nitric acid of nitrous gases.
Thus, a method of obtaining nitric acid, comprising the catalytic oxidation of ammonia, the absorption of oxides of nitrogen in nitrous gases, under pressure to 0.73 MPa and catalytic purification of exhaust nitrous gases. (see Atroshchenko Century, Alekseev A.M., and other Technology related nitrogen. - Kiev: Vyscha SHKOLA, 1985, s-260).
Bound method provides for the formation of nitric acid with the mass fraction of nitric acid 55-60% at relatively low compared with other economic costs. However, it is not possible to reduce the content of nitrogen oxides in the exhaust gas at the outlet of the absorption column below 0.1%, which leads to the catalytic purification of exhaust gases and limits the possibility of increasing the efficiency of the process.
The closest in technical essence to the claimed technical solution is the way to obtain nitric acid, comprising the catalytic oxidation of ammonia, the absorption of nitrogen oxides formed from nitrous gases, water and nitric acid under pressure of 1.1 MPa and catalytic purification of exhaust nitrous gases (see Vlasenko V.M., Samchenko NP and other Catalysis in nitrogen industry.- Kiev: Naukova Dumka, 1983, p.7). Is this the way for a combined scheme with pressure at the stage of oxidation of ammonia to 0.45 MPa, and at a station in the absorption of nitrogen oxides formed from nitrous gases 1.1 MPa.
The content of nitrogen oxides in the exhaust gas at the outlet of the absorption column is 0,07-0,1%, which implies the presence of costly site for catalytic purification of exhaust gases. The high content of nitrogen oxides in the exhaust gases due to the fact that the oxidation of nitrogen monoxide (NO) in the absorption column by its speed lags behind the process of absorption of nitrogen dioxide (NO2and reduce the degree of oxidation (NO2/(NO+NO2)) of nitrogen oxides during absorption from 93 to 50%. In other words, the process of absorption of nitrogen oxides in the absorption site is carried out in a sub-optimal ratio of the oxidizable monoxide nitrogen and absorbed nitrogen dioxide.
Such a sharp reduction in the degree of oxidation of the nitrogen oxides in this way makes it possible to maintain the driving force of the absorption process at a high level and, as a consequence, the degree of absorption in the implementation of the known method is not above 99,3%, which in turn causes the content of nitrogen oxides in the exhaust gases of at least 0.07%.
The aim of the invention is to increase the degree of absorption and the decrease in the obsession of nitrogen oxides in the exhaust nitrous gases.
Common features of the proposed technical solutions and prototype operations are catalytic oxidation of ammonia and absorption of nitrogen oxides formed from nitrous gases, water and nitric acid under pressure.
The difference is that in the proposed method, the process of absorption of nitrogen oxides with water and nitric acid in the absorption site is the ratio of the amounts of oxidized nitric monoxide by the reaction 2NO+O2→2NO2and absorbed nitrogen dioxide by the reaction 3N2+H2About→ 2N3+NO defined by the equation:
lg n=-(0,22÷ 0,29)-0,0626· lgPNOx.
Here n is the ratio between the amounts of oxidizable NO and absorbed NO2,
PNOx- the partial pressure of oxides of nitrogen in nitrous gas. In this case, the amount of oxidizable monoxide nitrogen means half the amount of content in the gas taking into account the need of secondary oxidation regenerative monoxide, and under the amount of absorbed nitrogen dioxide - total (NO2+NO), since the nitric monoxide after oxidation is subject to absorption. Thus, n=1,5 、 NO/NO2+NO.
The mathematical expression derived from experimental data to study the rate of absorption of nitrogen oxides depending on the ratio of the oxidizable what about the NO and absorbed NO; under pressure to 1.0 MPa (10.0 ATM) using a combination of mass transfer elements with a developed surface. The results of experiments to determine the optimal, ultimate and transcendent values of n are given in table 1.
Maintenance n within the specified limits is achieved by managing the process of oxidation of nitrogen monoxide by applying the combined mass transfer elements, the use of a certain gas pressure at the stage of absorption, oxidation of nitrogen monoxide advanced nitric acid concentration above the equilibrium, and the time of the homogeneous oxidation of nitrogen monoxide between the contact elements.
The deviation from the suggested n from PNOxin the direction of its reduction leads to unnecessary increase in capital and energy costs. When the deviation of n from the proposed dependence in the direction of its increase reduces the intensity of acid generating and, therefore, decreases the absorption of oxides of nitrogen nitrous gases.
The process of the proposed method will provide maintenance throughout the time of absorption of the high driving vultures absorption. The total absorption of nitrogen oxides will be at 99.95-of 99.97%, and the content of nitrogen oxides after the absorption column will be of 0,005 0,003%. Exhaust gases from such content is the use of oxides of nitrogen can be disposed of into the atmosphere without additional catalytic purification. In addition, the implementation process of the proposed method will also reduce the consumption of primary raw materials, ammonia is used to produce nitric acid.
Table 2 presents the results of the comparison of the efficiency of absorption of nitrogen oxides in the prototype and the proposed method. Here as a means of influencing the rate of oxidation in nitrogen oxides selected combined mass transfer elements.
It should also be noted the relationship between such technological parameters as the concentration of production of nitric acid, the amount of absorption volume and the content of oxides of nitrogen in nitrous gas after the absorption columns In the implementation of activities that will promote the intensification of the processes of absorption, it is possible to improve all of the above indicators (increased concentration of production of nitric acid, the decrease in absorption volume, the reduction of oxides of nitrogen in nitrous gas leaving the absorber column) or two one unchanging, or one with two unchanged. Thus, the proposed method can improve the number of process variables and parameters.
The method is as follows. Nitrous gases, obtained by catalytic oxidation of ammonia, cooled in otle-exchanger. Then perhaps the reaction water in refrigerators-capacitors, compressed in the turbocharger and doukissa before entering the absorption column in the hollow oxidizer or in the zonal absorber nitric acid with a concentration above the equilibrium. Next, nitrous gases are in absobtion column (AK), where absorption in the ratio of oxidized to NO and absorbed NO2according to the equation:
Ig n=-(0,22+0,29)-0,0626· lg PNOx
moreover, the regulation n carry out a combined mass transfer elements (LMEs). The absorption is carried out for the achievement of volume fraction of NOx absorbed gas is 0.005%, and then regenerating the energy of compressed gas, and it is released into the atmosphere.
The results of experiments to determine the optimal, ultimate and transcendent values of n are given in Table 1.
An example of the method are shown in Table 2.
The process was carried out in three areas of the absorption column At average concentrations of NOxwithin the first stage of 4.0%, the second is 0.55%, the third - 0.05 %, the ratio of n will be 0,61; to 0.66 and 0.75. To ensure these n zones in accordance with our experimental data it is necessary to apply masloobmennye elements (in the case of using them as a means of influencing the composition of nitrous is Aza) in the first zone 300 m 2second 350 m2in the third 400 m2when the gas pressure in the column of 1.1 MPa and the ratio of surface LMEs to volume 103 m2/m3.
Key performance indicators of the system are given in Table 3.
For irrigation of the third absorption zone is served steam condensate in accordance with the material balance, after the third zone of the acid with a mass fraction NGO32% is applied to the second irrigation zone resulting from the second zone 25% nitric acid is supplied to the first irrigation zone.
To compare the influence of the ratio of oxidized to NO and absorbed NO2the proposed method and the prototype on the value of the content of nitrogen oxides in the exhaust nitrous gases on the basis of experimental data calculated absorption site when changing n from of 0.60 to 0.75 and the use of combined mass transfer elements with a developed surface.
In all cases, the deviation of n from the dependencies in the direction of higher values leads to a decrease of the driving force absorption and, consequently, to reduce the speed of processing of nitrogen oxides to nitric acid in the absorption column.
In addition, the process of absorption of nitrogen oxides from head to tail system is not always the case reduce the concentration of oxides of nitrogen in nitrous gas (for example, when processing nitrous gas production of nitric KIS the Auteuil at the stage of washing or in the zonal absorber (condenser-doolitle), and in the case of the absorber from the lower area, working in recovery mode acids).
The proposed method is compared with the prototype allows to reduce the content of nitrogen oxides in the exhaust gas after the absorption column to 0.005% vol.
| Table 2 | |||||||||||
| An example of the method. | |||||||||||
| The proposed method | Prototype /AK-72/ | ||||||||||
| No. of area AK | No. of plates | Conc. NOx | Conc. HNO3 | Surface LMEs m2 | n | No. of area AK | No. of plates | Conc. NOx | Conc. HNO3 | Pressure, MPa | n |
| 1 | 1 | 7 | 60 | 300 | 0,59 | 1 | 1 | 7 | 60 | 1,1 | 0,6 |
| 5 | 2,8 | 42,8 | 0,62 | 5 | 3 | 46,2 | 0,7 | ||||
| 2 | 10 | 1 | 28,1 | 350 | 0,66 | 10 | 1,5 | 30,1 | 0,75 | ||
| 15 | 0,2 | 6,4 | 0,70 | 15 | 0,9 | 17,4 | 0,78 | ||||
| 3 | 20 | 0,01 | 0,3 | 400 | 0,72 | 20 | 0,5 | 8,4 | 0,80 | ||
| 25 | 0,004 | 0 | 0,80 | 25 | 0,3 | 3,2 | 0,83 | ||||
| 30 | 0,25 | 1,5 | 0,87 | ||||||||
| 35 | 0,2 | 1,0 | 0,9 | ||||||||
| 40 | 0,1 | 0,4 | 0,95 | ||||||||
| 45 | 0,07 | 0,01 | 1,0 |
| Table 3 The following are the main performance of the system. |
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| no PP | The performance of the system | The proposed method | The prototype AK-72 | Similar UKL-69 |
| 1. | The concentration of acid production, % | 50-65 | 60 | 55-60 |
| 2. | The degree of absorption, % | at 99.95 | 99-99,3 | 98-99 |
| 3. | The content of nitrogen oxides in the exhaust gases after absorption columns % | 0,005 | 0,1-0,07 | 0,2-0,1 |
| 4. | The presence of a catalytic purification | no | ||
| 5. | Expense ratio for ammonia, kg/t | 283,28 | 286 | 290 |
| 6. | Specific absorption volume, m2/t day | 0,68 | 0,68 | 0,7 |
| The ratio of n | 1 area of 0.54-0,65 | 0,57-1,0 | 0,57-1,1 | |
| 2 area of 0.62 to 0.70 | ||||
| 3 area 0,70-0,80 | ||||
| 8. | Surface LMEs m2 | zone 1 300 | no | no |
| zone 2 350 | ||||
| 3 area 400 | ||||
| 9. | Changes in the concentration of nitrogen oxides within the zone of absorption, % | 1 area of 7.0 to 1.0 | 7,0-a 0.1 | 7,0-a 0.1 |
| zone 2 1,0-0,1 | ||||
| 3 area of 0.1-0,005 |
The method of obtaining nitric acid, comprising the catalytic oxidation of ammonia and the absorption of oxides of nitrogen nitrous gases, water and nitric acid, characterized in that the absorption process is carried out in the absorption volume with different surface mass transfer elements in several areas of absorbs the frame volume ratio of oxidized monoxide nitrogen and absorbed nitrogen dioxide, defined by the equation
lg n=-(0,22÷0,29)-0,0626 lg PNOx,
where n is the ratio of oxidized to NO and absorbed NO2,
PNOx- the partial pressure of oxides of nitrogen in nitrous gas, MPa.