Method of producing nitric acid and apparatus for realizing said method

Abstract

The invention can be used in the chemical industry in the production of fertilizers. A method of producing nitric acid comprising the steps of compressing air to produce a stream of compressed air; producing a first and second stream of gaseous ammonia; producing an ammonia-air mixture; converting the ammonia-air mixture into nitrous gases; cooling the nitrous gases and absorbing same to produce nitric acid, while at the same time isolating a stream of tail gases; heating the tail gases with heat derived from the cooling of the nitrous gases; heating the tail gases in a combustion chamber of a turbine using heat from flue gases produced by the combustion of natural gas in the turbine combustion chamber; mixing the tail gases with the second stream of gaseous ammonia; catalytically purifying the tail gases in a selective purification reactor and isolating a stream of purified tail gases; recovering energy from the purified tail gases. An apparatus for producing nitric acid is also proposed. The invention provides more efficient purification of nitric acid production tail gases reduces NOx and N2O emissions into the atmosphere.

Description

[0001] METHOD FOR PRODUCING NITRIC ACID AND AN INSTALLATION FOR ITS IMPLEMENTATION

[0002] Field of technology

[0003] The proposed invention relates to a method and installation for producing nitric acid and can be used in the chemical industry and in the production of fertilizers.

[0004] Prior art

[0005] The following steps are traditionally used to obtain nitric acid from ammonia:

[0006] • air preparation and compression;

[0007] • preparation of gaseous ammonia;

[0008] • preparation of ammonia-air mixture;

[0009] • conversion of ammonia into nitrous gases;

[0010] • cooling of nitrous gas with heat recovery;

[0011] • absorption of nitrogen oxides;

[0012] • catalytic purification of exhaust (tail) gases from residual nitrogen oxides;

[0013] • energy recovery of purified exhaust gas;

[0014] • storage and distribution of production acid.

[0015] From D1 (A.P. Ilyin et al., Nitric Acid Production. Textbook. Ivan, State Chemical-Technological University, Ivanovo, 2011, Fig. 2.1) a method for producing nitric acid is known, including: a) a stage of air compression to obtain a compressed air flow, part of which is used to cool the elements of a gas turbine; b) a stage of preparing an ammonia-air mixture, including mixing ammonia with the compressed air flow obtained in stage a); c) a stage of converting the ammonia-air mixture obtained in stage b) into nitrous gases; d) a stage of cooling the nitrous gases obtained in stage c); e) a stage of absorption of nitrous gases obtained in stage d) to obtain nitric acid and isolate a tail gas stream; f) a step of heating the tail gases obtained in step e) in a first stage tail gas heater by cooling the nitrous gases; g) a step of heating the tail gases obtained in step f) in a combustion chamber of the reactor;h) a stage of catalytic purification (using a palladium-containing catalyst) of the tail gases obtained in stage g) from nitrogen oxides with the release of a stream of purified tail gases; i) a stage of mixing the purified tail gases with the flue gases of the turbine combustion chamber; j) a stage of converting the internal energy of the purified tail gases into mechanical energy.

[0016] In the proposed method, the catalytic tail gas cleaning stage precedes the heating of the tail gases in the turbine combustion chamber. Nitrogen oxides are formed in the combustion chamber and subsequently released into the atmosphere, reducing the environmental friendliness of the technology. Furthermore, the proposed method for catalytic tail gas cleaning uses a catalyst containing rare, hard-to-find palladium. This method also cools the gas turbine components using a compressed air flow, reducing the amount of compressed air that can be supplied to the process to increase nitric acid production.

[0017] The closest analogue of the present invention is the method known from D2 (A.P. Ilyin et al., Production of nitric acid. Textbook. Ivan. State Chemical-Technological University, Ivanovo, 2011, Fig. 2.15) for producing nitric acid, comprising a) a stage of compressing air to produce a compressed air stream, part of which is used to cool the elements of a gas turbine; b) a stage of producing first and second streams of gaseous ammonia; c) a stage of producing an ammonia-air mixture, including mixing the first stream of ammonia with the stream of compressed air obtained in stage a); d) a stage of converting the ammonia-air mixture obtained in stage c) into nitrous gases; e) a stage of cooling the nitrous gases obtained in stage d); f) a stage of absorption of nitrous gases obtained in stage e), with the production of nitric acid and the separation of a tail gas stream; g) a stage of heating the tail gases obtained in stage f) by cooling the nitrous gases obtained in stage d);h) a stage of catalytic purification of the tail gases obtained in stage g) in a selective purification reactor with the separation of a stream of purified tail gases, into which a second stream of gaseous ammonia obtained in stage b) is also fed; i) a stage of heating the purified tail gases obtained in stage h) in a turbine combustion chamber using the heat of the flue gases obtained from the combustion of natural gas in the turbine combustion chamber; j) a stage of energy recovery of the purified tail gases obtained in stage -;

[0018] In this method, the catalytic tail gas cleaning stage precedes the tail gas heating stage in the turbine combustion chamber. Nitrogen oxides are formed in the combustion chamber and subsequently released into the atmosphere, reducing the environmental friendliness of the technology. Furthermore, the vanadium catalyst used in the method generates additional nitrous oxide rather than promoting its removal, further reducing the environmental friendliness of the technology. This method also cools the gas turbine components using a compressed air flow, reducing the amount of compressed air that can be supplied to the technology to increase nitric acid production.

[0019] Disclosure of the essence of the invention

[0020] The objective and technical result of the present invention is to improve the environmental performance of nitric acid production by simultaneously reducing NO emissions. Xand N2O into the atmosphere. Additionally, increasing the energy efficiency of the technology while improving the environmental performance of production, increasing the efficiency of NO reduction Xat the system outlet to > 98.5%, increase in the efficiency of N2O reduction at the system outlet by > 97%, increase in the service life of the catalyst, with the calculated indicators from the start of operation: > 5 years after the first exposure to the gas. In order to solve the problem and achieve the technical result, a method for producing nitric acid is proposed, comprising a) a stage of air compression to obtain a compressed air stream; b) a stage of obtaining first and second streams of gaseous ammonia; c) a stage of obtaining an ammonia-air mixture, including mixing the first stream of ammonia with the compressed air stream obtained in stage a); d) a stage of converting the ammonia-air mixture obtained in stage c) into nitrous gases; e) a stage of cooling the nitrous gases obtained in stage d); f) a stage of absorbing the nitrous gases obtained in stage e), to obtain nitric acid and isolating a tail gas stream;g) a step of heating the tail gases obtained in step f) by cooling the nitrous gases obtained in step d); h) a step of heating the tail gases obtained in step g) in a turbine combustion chamber by using the heat of the flue gases obtained from burning natural gas in the turbine combustion chamber; i) a step of mixing the tail gases obtained in step h) with a second stream of gaseous ammonia obtained in step b); j) a step of catalytically cleaning the tail gases obtained in step i) in a selective cleaning reactor with the separation of a stream of purified tail gases; k) a step of recovering the energy of the purified tail gases obtained in step j).

[0021] Nitrogen oxides generated in the combustion chamber enter the selective purification reactor, where they are reduced to nitrogen. Thus, the proposed method reduces the nitrogen oxide content in the purified tail gas, which negatively impacts gas emissions. Conditions are provided for the removal (thermal decomposition) of nitrous oxide to nitrogen.

[0022] Under nitrogen oxides (NO X ) in this application refers to the oxides NO and NO2.

[0023] In this application, tail (exhaust) gases refer to nitric acid production gases exiting the absorption column with a nitrogen oxide content greater than 0.05%. Purified tail (exhaust) gases in this application refer to tail (exhaust) gases after catalytic purification of nitrogen oxides.

[0024] Preferably, a portion of the purified tail gas stream obtained in step )) is diverted as a side stream of purified tail gases for cooling in a purified tail gas cooling unit and then directed to cooling elements of a gas turbine.

[0025] In standard nitric acid production technologies, gas turbine components are cooled using a compressed air flow. The present invention proposes cooling turbine components using a purified tail gas flow. This allows the released air to be used in the process, further increasing the energy efficiency of the proposed method.

[0026] Preferably, in the cooling unit for purified tail gases, a two-stage cooling of the purified tail gases takes place: in the first stage - with water or by generating steam, in the second stage - with water.

[0027] In the case of using a single stage, an increased temperature difference between the refrigerant and the heat transfer fluids may be observed, which will lead to additional complexity of the design and to an additional decrease in the reliability of the heat exchanger.

[0028] Preferably, a zeolite catalyst, preferably a honeycomb zeolite catalyst, is used in the selective purification reactor.

[0029] The use of a honeycomb zeolite catalyst ensures a lower pressure drop and also leads to a reduction in the use of active catalyst components due to the ceramic carrier, ensuring ease of loading and operation of the catalyst - in particular, due to the absence of dust.

[0030] Preferably, Fe-ZSM-5, Fe-BEA, Fe-ZSM-12, Fe / HZSM-5, Fe-Ferrerite, Cu-ZSM-5, Cu-BEA, Cu-ZSM-12, Cu / HZSM-5, Cu-Ferrerite are used as the zeolite catalyst.

[0031] By modifying iron or copper to the beta position, the catalyst achieves increased efficiency in the nitrous oxide removal process without generating nitrous oxide (N2O), further enhancing the environmental friendliness of the process. Preferably, step k) of recovering the energy of purified tail gases involves converting the internal energy of the gases into mechanical energy of turbine rotation.

[0032] Energy recovery from purified tail gases further improves the energy efficiency of the technology.

[0033] Preferably, stage j) of catalytic purification of tail gases is carried out at a temperature of 450-700°C, preferably 550-600°C.

[0034] The specified temperature range allows for the most suitable conditions for the removal of nitrous oxide (i.e. for the thermal decomposition of nitrous oxide to nitrogen).

[0035] Also, in order to solve the stated problem and achieve the technical result, a nitric acid production unit is proposed, including a compressed air production unit connected to a compressed air flow discharge line; a gaseous ammonia production unit connected to a first ammonia flow discharge line and a second ammonia flow discharge line; an ammonia-air mixture production unit connected to a compressed air flow supply line, a first ammonia flow supply line and an ammonia-air mixture flow discharge line; an ammonia-air mixture conversion unit connected to an ammonia-air mixture flow supply line and a nitrous gas flow discharge line L1;a nitrous gas cooling and tail gas heating unit connected to a nitrous gas supply line L1, a cooled nitrous gas discharge line, a tail gas supply line L2 and a tail gas discharge line L3, configured to heat the tail gases by cooling the nitrous gases; a nitrous gas absorption unit connected to a cooled nitrous gas supply line, a nitric acid discharge line and a tail gas discharge line L2; a tail gas heating unit comprising a natural gas combustion chamber and connected to a tail gas supply line L3, and also configured to heat the tail gases with flue gases generated in the combustion chamber and connected to a tail gas discharge line L4;a tail gas purification unit comprising a selective purification reactor configured to purify tail gases using gaseous ammonia as a reducing agent, connected to a tail gas supply line L4 and a purified tail gas discharge line, wherein the L4 line is connected to a second ammonia flow supply line; a purified tail gas energy recovery unit connected to the purified tail gas supply line.

[0036] Preferably, the line for removing the flow of purified tail gases is configured to remove a side flow of purified tail gases.

[0037] Preferably, the installation comprises a purified tail gas cooling unit connected to a supply line for a side stream of purified tail gases.

[0038] Preferably, the tail gas cooling unit includes a tail gas cooling unit with water or by generating steam and a tail gas cooling unit with water.

[0039] Preferably, the selective purification reactor comprises a zeolite catalyst, preferably a honeycomb zeolite catalyst.

[0040] Preferably, the zeolite catalyst is a Fe zeolite or a Si zeolite, preferably Fe-ZSM-5, Fe-BEA, Fe-ZSM-12, Fe / HZSM-5, Fe-Ferrerite, Cu-ZSM-5, Cu-BEA, Cu-ZSM-12, Cu / HZSM-5, Cu-Ferrerite

[0041] Preferably, the purified tail gas energy recovery unit includes a unit for converting the internal energy of the gases into mechanical energy of turbine rotation.

[0042] It is further noted that all advantages of the present invention stated in relation to the method for producing nitric acid are equally applicable to the claimed installation and are not repeated here in order to avoid unnecessary duplication.

[0043] Brief description of the drawings

[0044] The drawings are presented for a better understanding of the invention, however, it will be obvious to a person skilled in the art that the disclosed invention is not limited to the embodiment shown in them.

[0045] Fig. 1 shows a diagram of the production of nitric acid according to the prior art. Fig. 2 shows a diagram of the production of nitric acid according to the present invention.

[0046] The best embodiment of the invention

[0047] The described embodiments are provided for illustrative purposes only. Those skilled in the art will readily recognize that other embodiments are possible without changing the essence of the invention.

[0048] In this application, a line is understood to mean a means for delivering a flow from one place to another, which, in particular, includes the pipes and connecting elements necessary for this, as well as, if necessary, control means and devices.

[0049] In this application, a block is understood to mean a device or a set of devices that ensure the implementation of the function specified for a given block.

[0050] It is further noted that, unless otherwise indicated, all positions (blocks, devices, lines) of the process flow diagrams designated identically in Figs. 1-2 imply complete functional identity.

[0051] Example 1 (prototype).

[0052] Fig. 1 shows a schematic diagram of the nitric acid production process according to the prototype. A stream of liquid ammonia is fed to unit 1 for preparing gaseous ammonia via line 100 from the plant network (not shown). Unit 1 prepares the gaseous ammonia stream, which is then fed via line 103 to unit 3 for preparing the ammonia-air mixture.

[0053] The atmospheric air flow is drawn into the axial compressor OK via line 200 through the air intake pipe (not shown) into the air preparation unit 2 (air filter), where it is purified. The air entering the axial compressor is preheated by feeding it hot air from the supercharger CN.

[0054] From air preparation unit 2, the purified air flow is fed via line 201 to the axial compressor OK, where it is compressed and heated. The air flow is then fed via line 202 to the intermediate air cooler VP, where it is cooled by recirculating water (not shown), and then via line 203 to the centrifugal supercharger CN, where it is compressed and heated. The axial compressor OK and the centrifugal supercharger CN of the GTT-3M gas turbine unit are driven by the gas turbine GT, which is structurally integrated into the same casing as the compressor.

[0055] From the blower, the air flow is fed through line 303 to block 3 for preparing the ammonia-air mixture.

[0056] Also, air is sent through line 208 to the purge column 8 as additional air for the oxidation of nitrogen oxide into dioxide and the purge of nitrogen oxides from the product acid.

[0057] In addition, the air flow through line 204 is directed into the combustion chamber of the UKST turbine.

[0058] In addition, part of the air flow is directed to the gas turbine of the GTT-3M unit to cool the elements of the flow part of the housing (not shown).

[0059] Next, in block 3 for preparing the ammonia-air mixture, where a flow of air is supplied through line 303 and ammonia through line 103, an ammonia-air mixture is formed, which is then purified from impurities and supplied to contact apparatus 4 through line 304.

[0060] In the contact apparatus, ammonia is oxidized to nitric oxide (II) and, partially, to nitric oxide (IV). The hot nitrous gases formed during ammonia oxidation enter the waste heat boiler (not shown). In the waste heat boiler, the cooling of the nitrous gases causes the feedwater to evaporate, producing superheated steam (not shown).

[0061] The nitrous gas stream obtained in contact apparatus 4 is sent via line 400 to oxidizer O with a built-in tail gas heater (UGS2), where nitrogen oxides (II) are oxidized to nitrogen oxides (IV). Next, part of the nitrous gas stream is sent to UGS2 and cooled by heating the tail gases in UGS2. The second part of the nitrous gas stream from O is bypassed by UGS2, then both streams are combined and fed via line 500 (L1) to the first-stage tail gas heater of the UGS. In the tail gas heater, the nitrous gases are cooled, heating the tail gases.

[0062] From the UGS, the flow of nitrous gases is fed through line 600 into the inter-tube space of the refrigerator-condensers 5, 6, where the flow is cooled by circulating water (not shown) coming from the absorption unit 7.

[0063] From the cooler-condensers, nitrous gases are fed via line 607 to absorption unit 7, where nitric acid is formed. The nitric acid stream after absorption unit 7 is fed to purge column 8, where nitrogen oxides are purged from it with hot make-up air. The purged (bleached) nitric acid from the purge column is discharged to one of the storage facilities via line 800. The purged gases from the purge column, to ensure complete oxidation of nitrogen oxide (II) (NO) to nitrogen oxide (IV) (NO2), are fed into the nitrous gas pipeline upstream of the absorption column via line 807.

[0064] The tail gas stream exiting the absorption column enters the UGS facility via line 706 (L2), where it is heated by nitrous gases. The tail gas stream is then sent via line 605 to the UGS2 tail gas heater, integrated into the oxidizer, where it is heated by the heat of the nitrous gases.

[0065] The heated tail gas stream is sent via line 606 to the selective purification reactor (RSO), where ammonia is also supplied via line 101. In the selective purification reactor, the process of reducing nitrogen oxides primarily to molecular nitrogen occurs at temperatures of 200–350°C.

[0066] A purified tail gas stream is generated in the RSO, which is fed via line 900 to the universal combustion chamber of the UKST turbine. The purified tail gas then enters the GT gas turbine via line 901. In the gas turbine, the internal energy of the gases is converted into mechanical energy (turbine rotational energy).

[0067] Next, the purified tail gases enter the gas turbine waste heat boiler (GTU) via line 902, then via line 904 to the economizer E, where they are cooled and then released into the atmosphere via line 905. In the waste heat boiler, superheated steam with a pressure of no more than 1.5 MPa is generated by cooling the purified gases, which is discharged via line 903 to the plant network (not shown). Heated deaerated chemically treated water (not shown) is used as feedwater for the waste heat boilers. The feedwater passes through the economizer E, where it is heated by the purified tail gases to a temperature and enters the GTU waste heat boiler. In the waste heat boiler, the heat from the purified tail gases causes the feedwater to evaporate, producing steam.

[0068] Example 2, and

[0069] Fig. 2 shows a modernized flow chart for producing nitric acid according to the present invention. The steps of the example implementation that are identical to the prototype are not repeated to avoid duplication.

[0070] The heated tail gas stream is directed through line 608 (L3) to the universal combustion chamber of the UKST turbine, where it is heated to 61СН-620°С due to mixing with flue gases obtained from the combustion of natural gas supplied through line 909, in a flow of air supplied through line 204. The tail gas stream leaving the combustion chamber is diverted through line 609 (L4), mixed with a flow of ammonia supplied through line 101, and supplied to the RSO.

[0071] The purification process is carried out with ammonia at a temperature of 45CH-700°C on a zeolite catalyst with a honeycomb structure in a vertical reactor according to the following reactions:

[0072] 4NO + O2 + 4NH3 4N2 + 6H2O

[0073] NO + NO2 + 2NH3 2N2 + 3H2O

[0074] 6NO2+ 8NH37N2+ 12H2O

[0075] Presence of NO X will promote the decomposition of N2O:

[0076] 2N2O 2N2+ O2

[0077] The purified tail gas stream leaving the RSO is diverted via line 901 to the gas turbine (GT). In the gas turbine, the internal energy of the gases is converted into mechanical energy (turbine rotational energy).

[0078] A portion of the purified tail gas stream is diverted via line 906 to the purified tail gas cooling unit 9. In the purified tail gas cooling unit 9, the purified tail gas is cooled in two stages: in the first stage, by generating steam, and in the second stage, by using water.

[0079] At the first stage, cooling of purified tail gases can also be carried out by additional heating of the feedwater of the GKU boiler or by using circulating water.

[0080] In the second stage of cooling the purified tail gases, recycled water from the plant's water circulation cycle can be used, as well as chemically purified or partially desalinated water to feed the waste heat boiler from the chemical water treatment shop.

[0081] The cooled, purified tail gas stream is diverted via line 907 and sent to cool turbine components (not shown). Compressed air is not used for cooling turbine components and is entirely consumed in the process to increase nitric acid production.

[0082] All of the above lines are equipped with flow rate, temperature, and pressure meters. Lines 606, 608, and 905 are additionally equipped with automated gas analyzers capable of measuring nitrogen oxide content.

[0083] The table below shows the results of the experiment (volume flow rate is adjusted to standard conditions: 20°C, 1 atm):

[0084]

[0085] Thus, the proposed group of inventions allows to ensure:

[0086] - improving the environmental performance of nitric acid production by simultaneously reducing NO emissions X and N2O into the atmosphere;

[0087] - increasing the energy efficiency of technology while improving the environmental performance of production;

[0088] - NO reduction efficiency X at the system output > 98.5%;

[0089] - efficiency of N2O reduction at the system outlet > 97%;

[0090] - increase in the service life of the catalyst, with calculated indicators from the start of operation: > 5 years after the first exposure to gas.

Claims

Invention formula 1. A method for producing nitric acid, comprising a) a step of compressing air to obtain a compressed air stream; b) a step of obtaining first and second streams of gaseous ammonia; c) a step of producing an ammonia-air mixture, including mixing the first stream of ammonia with the stream of compressed air obtained in step a); d) a step of converting the ammonia-air mixture obtained in step c) into nitrous gases; e) a step of cooling the nitrous gases obtained in step d); f) a step of absorbing the nitrous gases obtained in step e), to obtain nitric acid and isolating a stream of tail gases; g) a step of heating the tail gases obtained in step f) by cooling the nitrous gases obtained in step d); h) a stage of heating the tail gases obtained in stage g) in the combustion chamber of the turbine using the heat of the flue gases obtained from the combustion of natural gas in the combustion chamber of the turbine;i) a step of mixing the tail gases obtained in step h) with a second stream of gaseous ammonia obtained in step b); j) a step of catalytically cleaning the tail gases obtained in step i) in a selective cleaning reactor with the separation of a stream of purified tail gases; k) a step of recovering the energy of the purified tail gases obtained in step j).; 2. The method according to item 1, characterized in that part of the flow of purified tail gases obtained in step j) is diverted as a side flow of purified tail gases for cooling in a purified tail gas cooling unit and then sent to cool elements of the gas turbine.

3. The method according to item 2, characterized in that in the cooling unit for purified tail gases, two-stage cooling of the purified tail gases is carried out: in the first stage with water or by generating steam, and in the second stage with water.

4. The method according to claim 1, characterized in that a zeolite catalyst, preferably a zeolite catalyst with a honeycomb structure, is used in the selective purification reactor.

5. The method according to claim 4, characterized in that Fe-zeolite or Cu-zeolite is used as the zeolite catalyst, preferably Fe-ZSM-5, Fe-BEA, Fe-ZSM-12, Fe / HZSM-5, Fe-Ferrerite, Cu-ZSM-5, Cu-BEA, Cu-ZSM-12, Cu / HZSM-5, Cu-Ferrerite.

6. The method according to item 1, characterized in that stage k) of energy recovery of purified tail gases includes the conversion of the internal energy of the gases into mechanical energy of rotation of the turbine.

7. The method according to claim 1, characterized in that stage j) of catalytic purification of tail gases is carried out at a temperature of 450-700°C, preferably 550-600°C.

8. A nitric acid production unit comprising a compressed air production unit connected to a compressed air flow discharge line; a gaseous ammonia production unit connected to a first ammonia flow discharge line and a second ammonia flow discharge line; an ammonia-air mixture production unit connected to a compressed air flow supply line, a first ammonia flow supply line and an ammonia-air mixture flow discharge line; an ammonia-air mixture conversion unit connected to the ammonia-air mixture flow supply line and a nitrous gas flow discharge line L1; a nitrous gas cooling and tail gas heating unit connected to a nitrous gas supply line L1, a cooled nitrous gas discharge line, a tail gas supply line L2 and a tail gas discharge line L3, configured to heat the tail gases by cooling the nitrous gases;a nitrous gas absorption unit connected to a cooled nitrous gas supply line, a nitric acid removal line and a tail gas removal line L2; a tail gas heating unit comprising a natural gas combustion chamber and connected to a tail gas supply line L3, and also configured to heat the tail gases with flue gases generated in the combustion chamber and connected to a tail gas removal line L4; a tail gas purification unit comprising a selective purification reactor configured to purify tail gases using gaseous ammonia as a reducing agent, connected to a tail gas supply line L4 and a purified tail gas discharge line, wherein line L4 is connected to a supply line for a second ammonia stream; a purified tail gas energy recovery unit connected to the purified tail gas supply line.

9. The installation according to item 8, characterized in that the line for removing the flow of purified tail gases is designed with the possibility of removing a side flow of purified tail gases.

10. The installation according to item 9, characterized in that it contains a cooling unit for purified tail gases, connected to a supply line for a side stream of purified tail gases.

11. The installation according to item 10, characterized in that the cooling unit for purified tail gases includes a cooling unit for tail gases with water or by generating steam and a cooling unit for tail gases with water.

12. The installation according to item 8, characterized in that the selective purification reactor contains a zeolite catalyst, preferably a zeolite catalyst with a honeycomb structure.

13. The installation according to claim 12, characterized in that the zeolite catalyst is a Fe-zeolite or a Cu-zeolite, preferably Fe-ZSM-5, Fe-BEA, Fe-ZSM-12, Fe / HZSM-5, Fe-Ferrerite, Cu-ZSM-5, Cu-BEA, Cu-ZSM-12, Cu / HZSM-5, Cu-Ferrerite.

14. The installation according to No. 8, characterized in that the unit for recovering the energy of purified tail gases includes a unit for converting the internal energy of gases into mechanical energy of rotation of the turbine.

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