Method of modernization of an installation for production of nitric acid with its increased productivity
 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 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. |
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Method for production of nitric acid / 2248936 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 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: chemical industry; modernization of installations of nitric acid production according to a combined scheme.
SUBSTANCE: 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.
EFFECT: the invention ensures increased productivity of the installation at addition of small investments, which pay off less than for 1 year.
6 dwg, 1 ex
The method relates to the upgrade of the production of nitric acid in the combined schemes with the oxidation of ammonia with air under pressure, compressed nitrous gases in the compressor with turbodecoding and absorption of oxides of nitrogen under high pressure, mainly 3.5 kg/cm2.
This kind of installation with relatively low power and pressure at the stage of absorption of 3.5 kg/cm2continue now be operated at a number of enterprises of Russia and CIS countries.
Technological scheme of such facilities includes cleaning is sucked in from the atmosphere of air, compressing the mixture of air and ammonia coming from the gas tank, the ventilator to a pressure of ~1.08 kg/cm2heating the ammonia-air mixture (ABC) nitrous gases, oxidation of AVS in the contact device operating at a slight negative pressure (200-400 PA), on a two-stage catalyst at a temperature of 800-820°C, cooling hot nitrous gases (NG) in the HRSG, then the heater ABC, refrigerator-washer water cooled to 45-55°C, the mixture chilled NG with additional atmospheric air, which otdovat from the NOxproduction of nitric acid, compression NG in centrifugal supercharger (NIS) driven by a motor and turbolator to 3.5-4.1 kg/cm2cooling compressed NG, the absolute is bciu of nitrogen oxides in the absorption column, catalytic purification of the tail gas from the remnants of NOxin the reactor selective low-temperature purification at a temperature of ~260-300°With the extension of the tail gas in a gas turbine recuperator before being discharged into the atmosphere [1, p.69-78].
As wear nitrous supercharger capacity of the plant is reduced; at the same time decreases the compression ratio NG and concentration of nitric acid, which together negatively affects its cost.
Therefore, at present the main task is to modernize these plants with increased inefficiency in excess of the project within the pressure increase, the allowable strength characteristics of the devices stage of absorption.
During long-term operation of these facilities was made upgrades to increase the concentration of nitric acid (installation of refrigerator NG at the entrance to the absorption column), reducing the content of nitrogen oxides in the tail gas at the outlet of the absorption column (cooling side plates cooled to +5°water); the installation of selective catalytic reactor tail gas treatment unit to a residual content of NOx0,005% [see 2, p.63-66].
These upgrades were decided separately specific objectives, without increasing performance units, which has led the ILO to increase the cost of nitric acid.
The aim of the present invention is a method upgrade to 3.5 MPa with increase performance up to 20% with a simultaneous increase in the concentration of nitric acid 47-49% to 50-53% HNO3by reducing the content of nitrogen oxides in the tail gas after a column to 0.1-0,11%. As a consequence, reduced the cost of ammonia, electricity, demineralized water 1 T. NGO3the cost of production.
The essence of the invention lies in the fact that to achieve this goal increase the pressure of the nitrous gases at the inlet of the nitrous supercharger one of the following ways:
- installation of a new gas ammonia-air mixture with a higher pressure in the discharge line or additional to existing one;
- install gas line nitrous gases after cooling to 40-50°in fridge-washer;
- reduction of hydraulic resistance machines and devices on pipelines from the air intake from the atmosphere to the suction nitrous gases supercharger (NIS).
When the pressure NG on the suction side of the compressor increases its performance and compression ratio according to the aerodynamic performance of the compressor 541-41-1 (see figure 3-6), which is installed in the upgraded facilities. The greatest increase in the pressure at the inlet of the NIS is achieved by installing additional is sustained fashion (or the new higher-pressure) gas line ammonia-air mixture or a new gas line nitrous gases.
The authors of the present invention is unknown how modernization with improved performance of the units for a combined scheme with the oxidation of ammonia with air under pressure, and with the absorption of oxides of nitrogen under an average pressure of 3-5 kg/cm2in which in order to intensify the increased pressure nitrous gases at the inlet of the nitrous supercharger.
Unknown plant with ammonia under pressure, which initially had excessive pressure on the inlet of the NIS.
In modern large-capacity units on a combined scheme of the oxidation of ammonia produced under a pressure of 3-5 kg/cm2and the absorption of oxides of nitrogen under pressure 9-15 kg/cm2[2]. Therefore, the authors cannot specify a close analogue of the proposed method retrofit installations on a combined scheme with oxidation under vacuum, or any apparatus for the production of nitric acid.
One of the essential features of the present invention is to limit the upper level of the pressure at the inlet of the NIS pressure of 1.02-1.05 kg/cm2that is associated with the strength characteristics of the devices stage of absorption and aerodynamic characteristics of nitrous supercharger 540-41-1. As the determining apparatus adopted the absorption column, the strength of which, according to the passport data, admits ve is chna part of the apparatus, the pressure is not more than 4 kg/cm 2. According to calculations, if the maximum performance of the unit nitric acid 6.9 tons/hour (20% above design, the maximum allowable for the modernized installation), that is, when the flow rate through the column 29500 m3/h NG pressure loss in the path of the "NIS - oxidant-tail gas heater - refrigerator - lower part of the absorption column is ~ 0.8 kg/cm2. Therefore, the allowable pressure on the injection of NIS after the intensification accepted 4.8 kg/cm2.
According to the aerodynamic performance of the compressor 540-41-1, that pressure above the gas flow is achieved at a temperature of 40°and the pressure at the inlet of 1.02 kg/cm2and at 60° - 1.05 kg/cm2.
The pressure increase nitrous gases at the inlet of the NIS can be produced according to two schemes:
the first scheme is to increase the pressure of the ammonia-air mixture (ABC) in the head installation. The level of increase of pressure the FAA to obtain pressure nitrous gas at the inlet of the NIS in the range of 1.02-1.05 kg/cm2taking into account losses in the resistance of the path ABC “ventilator ABC gas heater ABC - regulating valve filter ABC” at the end of the run and tract nitrous gas “bottom contact device - boiler - heater ABC - refrigerators-washers - site mixing with air - gas”, according to the calculations is 0.12 kg/cm 2. For this you can install a new ventilator, but preferably in series with the existing ventilator TG-500-1,08 set the same ventilator, which, besides reducing the volume of investment, allows the cost-effective to solve the problem of the start pin of the device under vacuum (only one gas). According to this scheme, in nominal mode contact apparatus for the oxidation of ammonia will work under pressure 1.125 kg/cm2;
- second circuit - compression cooled to 45-55°With nitrous gases after refrigerators-washers-blowers with a total pressure of 0.1-0.12 kg/cm2. Blowers shall be made of stainless steel. According to this scheme, contact the systems operate under pressure.
The present invention also includes modernization of installation without additional pumping devices; in this embodiment, the pressure increase nitrous gases at the inlet of the NIS is carried out by reducing the hydraulic resistance of the devices on the path to the NIS.
On the path of the ammonia-air mixture reducing the loss of gas pressure can be achieved:
- change the design of the air filter and replace the filter material on the material with less resistance;
- with the exception of the throttle valve on the line ABC;
- installing a second heater ABC that gives even and reduced the e resistance on the path nitrous gas;
- redesign and replacement of the filter material in the filter ABC.
According to approximate calculations it may reduce pressure losses in the lines ABC and NG to 400-500 mm century Art. In this embodiment preserves the vacuum in the suction pipe NIS, and productivity will reach no more than 8% of the project.
Below are examples of the implementation of the present invention to circuits with installation of additional injection devices.
Example 1 (figure 1).
The air taken from the atmosphere, is filtered in the filter 1. The ammonia-air mixture compressed in the existing ventilator (pos.2) under a pressure of 1.06-1.08 kg/cm2is fed to the inlet of the newly installed gas circulators (3) with a capacity of up to 30,000 m3/HR and head up to 0.12 kg/cm2in the suction conditions (temperature of 20-35°C, a pressure of 1.06-1.08 kg/cm2). In the newly established ventilator pressure ABC increases to 1.18-1.2 kg/cm2. Heated ABC and cooling nitrous gases are produced in existing process equipment. Heated ABC is served in the contact device (pos.4), which translates to a mode of operation under pressure to 1.125 kg/cm2. For this purpose, the contact device is being upgraded to increase its impermeability. Nitrous gas is cooled in the existing apparatus and is supplied to the inlet of nitrous supercharger (5)under pressure of 1.02-1.05 kg/cm 2. Compressed to 4.7-4.8 kg/cm2nitrous gases go further processing in the absorption Department, which if necessary is made efforts to provide for the operation of vehicles under this pressure. In connection with the transition to the operation mode with vacuum gauge pressure at the inlet nitrous supercharger for supplying an auxiliary air and purge gases from the column blowdown (pos.6) nitric acid from dissolved nitrogen oxides, installation of the fan (pos.7), which delivers air under pressure greater than the excess pressure at the inlet of the NIS on the resistance of the purge column and piping systems.
Example 2 (figure 2).
In this embodiment, the upgrade installation after cooling nitrous gases in refrigerators-washers up to 50-55°With increasing pressure nitrous gases from 0.92-0.93 kg/cm2to 1.02-1.05 kg/cm2produced by blowers (POS. 1). On the suction side of these blowers supplied extension and the purge air, which before modernization was supplied to the inlet of nitrous supercharger. This option does not require sealing contact of the device.
Next, nitrous gases are compressed in nitrous compressor 2 to a pressure of 4.7-4.8 kg/cm2and fed to the absorption system.
Upgrading installation options described in examples 1 and 2, provides increased productivity is eljnosti 15-20% from original to modernization, this 20% increase in productivity refers to the upper limit of the pressure at the inlet nitrous supercharger to 1.05 kg/cm2.
Modernization of installation without the use of additional blowers on the lines of the ammonia-air mixture or nitrous gases, but with reduced pressure loss through the line ABC and nitrous gases to the suction nitrous supercharger due to the technical solutions described above allows to increase plant capacity by 8%.
The examples illustrate the invention but do not restrict it.
Literature:
1. Directory of apothica, vol. 2. M.: Chemistry, 1969, p.69-78
2. Directory of apothica, 2nd edition, book 2. M.: Chemistry, 1987, p.63-66.
Upgrade installation for the production of nitric acid, comprising the oxidation of ammonia with air under pressure, compression chilled nitrous gases nitrous supercharger, the absorption of nitrogen oxides in the absorption column under a pressure of 3.5-4.0 kg/cm2the exhaust extension tail gas in the expander, wherein the boost pressure of the nitrous gases at the inlet of the compressor in the range from vacuum up to a pressure of 1.02-1.05 kg/cm2install a new or additional gas lines ammonia-air mixture or nitrous gases or decrease the hydraulic resistance of the devices is tov and devices on pipelines to suction nitrous supercharger.