A method for the synthesis of ammonia

Abstract

Present invention relates to a method for the synthesis of ammonia, where a hydrogen (1) from an electrolyser (G) and a nitrogen (2) from a nitrogen production unit (D) are fed to a nitrogen-hydrogen mixture compression unit (A) and from there said mixture (3) is fed to an ammonia synthesis unit (B). Heat from steam-hydrogen steam from a electrolyser (G), heat generated during compression of the nitrogen-hydrogen mixture in the compressor stages of the nitrogen-hydrogen mixture compression unit, and heat released during the synthesis reaction in the ammonia synthesis unit, is used to generate steam for an electrolysis in the electrolyser. Liquid ammonia is separated from the circulation gas entering the separation unit from the steam generation unit using condensation at temperatures at an ambient environment temperature.

Description

A method for the synthesis of ammoniaTECHNICAL FIELD

[0001] Present invention relates to a method for producing so called green ammonia, where use of fossil fuels is eliminated. More specifically invention related to a method for the synthesis of ammonia.BACKGROUND ART

[0002] Traditionally the ammonia is synthesized industrially through the Haber- Bosch process, which involves reacting a nitrogen molecule with three hydrogen molecules over a bed of catalyst. The reaction takes places at high pressures and at temperatures 400 to 500°C.

[0003] The traditional raw material for industrial ammonia production is fossil natural gas. In gas preparation schemes, including reforming of natural gas, steam reforming of CO, purification of CO2 and methanation, a nitrogen-hydrogen mixture is produced. Reforming of natural gas consists of two stages - steam reforming and steam-oxygen reforming. Air is supplied to the steam -oxygen reforming reactor along with the converted gas from the steam reformer. The oxygen from the air is consumed for the exothermic reactions on the catalyst, and the nitrogen remains in the converted gas. After passing through further stages of CO conversion and purification, a nitrogen-hydrogen mixture with a ratio (Mole ratio) of H2 / N2=3 / 1 is obtained, which is sent directly to the ammonia synthesis stage.

[0004] The method for producing “green” ammonia, in the method a synthesis gas is used for producing an ammonia, which is obtained from the raw materials such as hydrogen and nitrogen, where the hydrogen is obtained by electrolysis of a water and the nitrogen is obtained from the air.

[0005] In the known methods a nitrogen-hydrogen mixture compression unit comprises multiple compression stages cooled by a circulating water. The water circulation cycle includes pumping systems for circulating water and cooling systems for circulating water (cooling towers, air cooling units, etc.), which operate on the principle of transferring heat from water to the atmosphere. This heat energyis not used in the process but is released unused into the environment.

[0006] In the known methods for producing steam for electrolysis of the SOEC- electrolyser, steam is produced conventionally in an electric steam generator that consumes a significant amount of electricity. Use of electricity decreases energy efficiency of the overall process.

[0007] In known methods, tank gases are in many cases directed to burners of a steam reformers for hydrogen production. In that case, hydrogen, the production of which has already consumed material and energy resources, and which has a low- calorie content, is burned in a furnace, and nitrogen, which has also gone through a number of technological stages, is returned to the atmosphere. This practice also decreases energy efficiency of the overall process.

[0008] In known solutions, where a stream leaving the SOEC electrolyzer contains hydrogen and water vapor, the stream is cooled and the hydrogen is dried, the heat of the stream is dissipated into the atmosphere, and the separated water is sent to drainage.

[0009] In most ammonia production methods and equipment, an ammonia cooling and condensation unit includes a cooling system with an ammonia compressor, consisting of at least compressor, heat exchanger and other equipment.

[0010] European patent EP3695027B1 discloses a method for generating synthesis gas for ammonia production. Said method comprising the steps of feeding a mixture of steam and compressed air into the electrolysis unit or into the first of a series of electrolysis units. The outlet from one electrolysis unit fed to the inlet of the next electrolysis unit, either together with air added after each electrolysis unit or only adding air after the last electrolysis unit. A part of the synthesis gas is provided by burning the hydrogen produced by steam electrolysis by air in or between the electrolysis units. The basic idea underlying said solution is to make ammonia synthesis gas by electrolysis, e.g. in SOEC stacks, without having to use air separation. After obtaining the nitrogen-hydrogen mixture, it is purified from oxygencontaining impurities by methanation.

[0011] W02023020771A1 discloses a method for producing synthesis gas for theproduction of green ammonia. The method includes the steps of: (a) supplying a separate stream containing nitrogen by absorbing ambient air under varying pressure; (c) producing a separate stream containing hydrogen by electrolysis of water and / or steam; (c) combining the individual streams obtained in steps a) and c) into a mixed stream containing hydrogen and nitrogen; (d) increasing the pressure of the mixed stream from step (c); and (e) removing residual amounts of oxygen further contained in the mixed stream by catalytically hydrogenating oxygen with a portion of the hydrogen contained in the mixed stream in the upstream step (d) and / or in the subsequent step (d) and / or during the step (d) for the production of ammonia synthesis gas.

[0012] In the above-mentioned prior art solutions excess energy in the form of heat is not used or only the heat that is released mainly during the synthesis of ammonia is partly used.

[0013] Also, in the mentioned solutions, the pure and expensive hydrogen produced in electrolysis is used in an inefficient way by burning it in the process, and / or using it for removing impurities from the synthesis gas through hydrogenation or methanation.

[0014] Since in the above mentioned solutions argon is present in nitrogen for ammonia synthesis, which determines a need for a constant purge during ammonia synthesis, part of hydrogen also leaves with constant purge and tank gases. The amount of hydrogen that are not spent on ammonia synthesis, which accordingly entails an increase in costs for the construction of electrolysis capacities with a corresponding increase in the volume of water treatment and other infrastructure. Also, due to inappropriate (not for the needs of ammonia synthesis) consumption of electrolysis hydrogen, the consumption of “green” electricity, which is used for the electrolysis process, increases accordingly.DISCLOSURE OF INVENTION

[0015] The aim of the invention is to provide a method for the synthesis of ammonia, where use of fossil fuels as raw materials is eliminated. Also the aim of the method of the invention is to use pure, expensive raw materials, namely the hydrogenproduced by electrolysis and cryogenic nitrogen only for the ammonia synthesis. Also, the aim of the invention is to provide method for the synthesis of ammonia, where for condensation (liquation) of ammonia is performed without additional cooling equipment and at the temperatures of ambient environment.

[0016] The aim of the invention is also to provide a method for synthesis of ammonia, where heat (energy) generated in the process of the ammonia synthesis is used to generate hydrogen for the ammonia synthesis - the aim is to provide a method where, in the process of the production of ammonia, production of hydrogen is implemented using energy in the form of heat derived from the ammonia production process. In other words, the aim is to provide a method of ammonia with a maximum use of energy, which generated in ammonia production.

[0017] The aim of the method of the invention is also to enable use of simpler equipment.TECHNICAL PROBLEM

[0018] Technical problems to solved by the provided method is to increase energy efficiency of the method through the use of excess heat generated during the compression of hydrogen and nitrogen-hydrogen mixture, use of a raw nitrogen and hydrogen for the purpose of the ammonia synthesis only, to reduce in the synthesis of ammonia and in the production of hydrogen a labour intensity of the equipment necessary for the implementation of ammonia liquefaction at ambient temperatures.TECHNICAL SOLUTION

[0019] Present invention proposes a method for the synthesis of ammonia, comprising the following steps, where in: step a) a hydrogen from an electrolyser and a nitrogen from a nitrogen production unit are fed to a nitrogen-hydrogen mixture compression unit and from there said mixture (3) is fed to an ammonia synthesis unit; step b) a circulation gas from the ammonia synthesis unit is fed to a steam generation unit, where the heat released during the synthesis reaction in the ammonia synthesis unit is transferred by said circulating gas, is used to generatesteam for an electrolysis in the electrolyser; step c) a cooled circulation gas from the steam generation unit is fed to a separation unit, where ammonia is separated from said circulation gas and said separated circulation gas is fed back to the ammonia synthesis unit; step d) the tank gases comprising hydrogen, nitrogen and gaseous ammonia separated from the separated liquid ammonia, are fed from the separation unit to the nitrogen-hydrogen mixture compression unit and are fed back to the ammonia synthesis unit; step e) heat of steam -hydrogen stream (15) from electrolyser (G), heat generated during compression of the nitrogen-hydrogen mixture in the compressor stages of the nitrogen-hydrogen mixture compression unit and heat generated during compression of hydrogen in the compressor stages of the hydrogen compressor, is used to heat in the steam generating unit an incoming water fed to the steam generation unit from the water treatment unit; step f) liquid ammonia is separated from the circulation gas entering the separation unit from the steam generation unit using condensation at temperatures at an ambient environment temperatures; step g) water condensate separated from the hydrogen at the outlet of the electrolyser is fed to the water treatment unit.

[0020] The synthesis process in the ammonia synthesis unit is carried out at temperatures of 360-510°C without constant purging.

[0021] In step a the nitrogen-hydrogen mixture from compression unit and is fed to said ammonia synthesis unit at pressure 12.0 to 20.0 MPa.

[0022] Excess heat generated during the step b) of the synthesis, and also heat from steam-hydrogen stream from electrolyser of the step e), is used for the steam generation: i) the heat generated during compression of the nitrogen-hydrogen mixture in the compressor stages of the nitrogen-hydrogen mixture compression unit andhydrogen compressor, is used to heat in the steam generating unit an incoming water fed to the steam generation unit from the water treatment unit; ii) the heat of the steam -hydrogen stream from electrolysis is used to heat incoming water in the steam generating unit, supplied to the steam generating unit from the water treatment unit; iii) the heat released during the synthesis reaction in the ammonia synthesis unit, which is transferred by circulating gas, is used to generate steam for an electrolysis in the electrolyser.

[0023] Also, according to present invention, liquid ammonia is separated from the circulation gas entering the separation unit from the steam generation unit using condensation at temperatures at an ambient environment temperatures. The condensation of the ammonia at the ambient environment temperatures is carried out at temperatures between -40 and +50 °C, preferably between -20 and +40 °C.

[0024] In order further increase the efficiency of the process, water condensate separated from the hydrogen at the outlet of the electrolyser, is fed to the water treatment unit.

[0025] Said electrolyser is SOEC-electrolyser, that in an electrolyser based on SOEC (Solid Oxide Electrolysis Cell) stacks.

[0026] The nitrogen is produced in the nitrogen production unit by a cryogenic separation of the nitrogen from the ambient air, which has a purity of no less than 99.99%.

[0027] Preferably said nitrogen-hydrogen mixture fed to an ammonia synthesis unit has pressure from 10 MPa to 25 MPa (~99 to 250 at).ADVANTAGEOUS EFFECTS

[0028] A heat of interstage cooling of nitrogen-hydrogen mixture compressor and hydrogen compressor is used to produce water vapor for the SOEC-electrolyser.

[0029] The interconnections between the nitrogen-hydrogen mixture compression unit (A), hydrogen compressor and the steam generation unit (E) allow transfer ofheat energy from the interstage cooling of the nitrogen-hydrogen mixture compressor and hydrogen compressor to the production of water vapor, which used for a hydrogen generation in the SOEC-electrolyser for subsequent ammonia synthesis.

[0030] As a result, the following benefits are achieved:1. The problem of cooling the nitrogen-hydrogen mixture compressor and hydrogen compressor is solved; there is no need for a water circulation cycle with corresponding consumption of water, electricity and energy dissipation into the environment.2. The problem of providing heat to produce steam to power the electrolyser is solved.

[0031] The heat of the synthesis gas and hydrogen heated during compression is used directly for a steam generation, which reduces the energy consumption of the entire complex for the production of “green” ammonia.

[0032] Heat released during the ammonia synthesis reaction is used to produce water vapor for the SOEC-electrolyser.

[0033] There is implemented interconnection between the ammonia synthesis unit (B) and the steam generation unit (E) by transferring heat obtained from the exothermic reaction of ammonia synthesis to the production of water steam, from which hydrogen is produced for synthesis in the SOEC-electrolyser (unit G).

[0034] As a result, the following benefits are achieved:1 . The problem of cooling the circulating gas is solved - there is no need for a water circulation cycle, with corresponding consumption of water, electricity and energy dissipation into the environment;2. The problem of providing heat to produce steam to power the electrolyser is solved - this eliminates the need for external energy sources to produce steam.

[0035] In addition, the above listed benefits make it possible to provide main volumeof the steam for the production of hydrogen for synthesis in the SOEC-electrolyser, which makes it possible to reduce the overall energy consumption of hydrogen production and production of ammonia in general.

[0036] Use of tank gases for ammonia synthesis.

[0037] The possibility of using tank gases for ammonia synthesis is ensured by the fact that high-purity nitrogen containing no argon is produced in the nitrogen production unit (D) using a cryogenic separation of nitrogen from the air. At the same time, the SOEC-electrolyser (G) produces high-purity hydrogen that does not contain methane.

[0038] A consequence of the absence of inert components, such as argon and methane in synthesis gas, is that the composition of tank gases released from liquid ammonia in the separation unit (C) practically corresponds to the composition of the nitrogen-hydrogen mixture for synthesis and can be fed to the inlet of the nitrogenhydrogen mixture (synthesis-gas) compression unit (A).

[0039] As a result:1 . tank gases are not burnt and therefore tank gases do not pose a harm to the natural environment;2. additional ammonia is produced from tank gases, increasing the productivity of the plant.

[0040] According to invention the use of tank gases for ammonia synthesis is possible, because the cryogenic air separation allows to obtain high-purity nitrogen without argon. Also, in the hydrogen production scheme of the invention, the SOEC- electrolyser produces high-purity hydrogen with the absence of impurities such as methane. This means, that the composition of tank gases practically corresponds to the composition of fresh synthesis gas.

[0041] Return of the condensate after hydrogen drying (separation).

[0042] From the exit from the SOEC-electrolyser (G), wet hydrogen (that is stream of hydrogen with water vapor) undergoes drying and the hydrogen is sent to the inlet of a hydrogen compressor, and the water condensate is sent to the water treatmentunit (F).

[0043] As a result, the consumption of water in the water treatment unit is reduced with a corresponding reduction in chemical reagents that are used for water purification, with reduced labor intensity and energy consumption for purifying source water.

[0044] In the solution of the invention, water condensate after hydrogen drying is sent for deaeration and added to purified water, which is supplied from the water treatment unit to the steam generation unit.

[0045] Ammonia condensation is achieved without using an ammonia compressor.

[0046] After the circulating gas has given up its heat to produce steam in a steam generation unit (E), liquid ammonia condenses in the separator of the separation unit (C) at an ambient temperature.

[0047] This possibility of abandoning traditional ammonia condensation using an ammonia compressor is possible, because in the method of the invention there are no inert components in the synthesis gas - in known methods for the synthesis of ammonia, in addition to hydrogen and nitrogen, the synthesis gas contains significant concentrations of inert components, the main of which are methane and argon.

[0048] As a result, there is eliminated a need to cool the circulating gas using an ammonia compressor. This is a significant reduction in the number of technological equipment and, accordingly, a simplification of the overall production scheme and algorithms for monitoring and managing technological processes.

[0049] In the present invention, there is no ammonia cooling system, which significantly reduces the amount of technological equipment - the ammonia compressor, separators, expansion tanks, heat exchangers, air cooling units with the corresponding system of instrumentation and controls are excluded from the production scheme.

[0050] This has become possible thanks to the implementation of other solutions that are applied in the production method of the invention - the cryogenic productionof pure nitrogen and the electrolytic production of pure hydrogen. Since the condensation of ammonia gas is carried out at ambient temperature, the concentration of ammonia in the circulation gas is higher than in the known solutions. But the absence of inert components allows the process of ammonia synthesis to be carried out effectively with a gas circulation.

[0051] With the invention is achieved:- use of heat from steam-hydrogen stream at the outlet of the electrolyser to heat inlet water fed to steam generation;- use of heat of compression stages of hydrogen compressor and compressor of nitrogen-hydrogen mixture compression unit;- use of synthesis heat for generation of the water vapor for electolysis;- use of tank gases for synthesis;- ammonia condensation at ambient temperature.

[0052] Additionally:- use of compressor interstage cooling heat;- return of water condensate after hydrogen drying to the water treatment system.

[0053] The overall effect of the implementation of the invention:The integrated application of solutions for the proposed method, as well as the relationship between the solutions, which lies in the fact that thanks to the use of some of the proposed solutions, the possibility of using other solutions is achieved, made it possible to obtain an energy-efficient scheme for the synthesis of ammonia with a reduction in the consumption of “green” electricity for steam production up to 70%, a reduction in consumption feed water for hydrogen production up to 18%, reducing water consumption for cooling process flows by up to 85%, as well as reducing thermal energy emissions into the external environment up to 1.5 MW / t (MW / t = MW per ton) of green ammonia.BRIEF DESCRIPTION OF DRAWINGS

[0054] In the following present invention is described in more detail manner with references to the accompanying drawing where:Figure 1 is a schematic flow chart of the method of the invention for the synthesis of ammonia.MODE(S) FOR CARRYING OUT THE INVENTION

[0055] The ammonia production scheme consists of the following main elements:A - Nitrogen-hydrogen mixture compression unit - designed to compress hydrogen and nitrogen from the pressure at which they are produced to the synthesis pressure.B - Ammonia synthesis unit - designed for the catalytic synthesis of ammonia from nitrogen and hydrogen.C - Separation unit - designed for cooling the circulating gas, condensing gaseous ammonia and releasing liquid ammonia.D - nitrogen production unit - a cryogenic nitrogen separation unit from air, which designed to produce nitrogen for ammonia synthesis.E - Steam generation unit - designed to produce water steam for the electrolyser.F - Water treatment unit - water preparation unit intended for the production of boiler quality water, that is purified water for generating steam in the steam generation unit to be used in the electrolyser.G - SOEC-electrolyser - designed to produce hydrogen from water vapor.

[0056] The ammonia production scheme works as follows. The nitrogen production unit D, where a cryogenic separation of nitrogen from the air is used, produces pure nitrogen containing no argon.

[0057] The nitrogen flow 2 enters the suction of the booster compressor (unit A). Hydrogen (stream 1 ), which is produced in the electrolyser (unit G) from water vapor (stream 10), produced in the steam generator unit E, is sent to the suction of the same booster compressor (unit A).

[0058] To produce steam, several process streams enter unit E, the heat of which isused to heat water and generate steam. Heat of interstage cooling of compressor of unit A (stream 4) and heat from hydrogen compressor in unit G (stream 15) is used in unit E to heat the incoming water (stream 9) from water treatment unit F. For steam generation in unit E, the heat of the circulation gas flow (stream 6) is used, which is sent from ammonia synthesis unit B to unit E.

[0059] From the water vapor (stream 10) produced in unit E, hydrogen is produced in the electrolyser (unit G) for the synthesis of ammonia. After drying the mixture of hydrogen and steam, the hydrogen is sent (stream 1 ) to the suction of the booster compressor in unit A, and the water condensate (stream 11 ) is returned to the water treatment unit F and added to the feed water (stream 12).

[0060] The circulation gas (stream 13), which has given up its heat to produce steam, is sent from the steam generation unit E to the separation unit C. Here, gaseous ammonia is condensed into a liquid state. Tank dissolved gases are separated from liquid ammonia and sent to the suction of the booster compressor in unit A (stream 5), and liquid ammonia (stream 7) is sent to the warehouse. The separated circulation gas (stream 14) is returned to the ammonia synthesis unit B.

[0061] Additionally, a heat from unused water vapour containing hydrogen (stream 15) from electrolyser G is used to is used in unit E to heat the incoming water (stream 9) from water treatment unit F.

[0062] The nitrogen-hydrogen mixture compressed in unit A (stream 3) is sent to ammonia synthesis unit B, in which circulation catalytic synthesis of ammonia gas is carried out.

[0063] Thus, the presented ammonia production scheme fully utilizes the heat released due to exothermic processes occurring during compression of synthesis gas and in the catalytic synthesis of ammonia, despite the fact that raw hydrogen and nitrogen are completely used for ammonia synthesis.

[0064] Following is an example of the implementation of the method of green ammonia production with an amount of about 22500 tons per year. The ammonia production scheme works as follows. Nitrogen production unit D, which uses cryogenic separation of nitrogen from air, produces nitrogen with a purity of99.999%, containing no argon, in a volume of about 1766.7 m3 / hour.

[0065] Nitrogen flow 2 enters the suction of the booster compressor (unit A). Hydrogen (stream 1 ), in the amount of about 5300 m3 / hour, which is produced in the electrolyser (unit G) from water vapor (stream 10) produced in the steam generator unit E, is sent to the suction of the same booster compressor (unit A).

[0066] To produce steam, several process streams enter unit E, the heat of which is used to heat water and produce steam. The heat of interstage cooling of the booster compressor of unit A (stream 4) and the hydrogen compressor of unit G (stream 15) is used in unit E to heat about 5142 kg / h of feed water from water treatment unit F (stream 9). Also, to heat the incoming water, the heat of the steam -hydrogen stream 15 at the outlet of the electrolyser G is used. To generate steam in unit E, the heat of the circulating gas stream having a temperature of 300-330°C (stream 6) is used, which is sent from the ammonia synthesis unit B to the unit E.

[0067] From the water vapor (stream 10) obtained in unit E, about 5300 m3 / hour of hydrogen is obtained in the electrolyser (unit G) for the synthesis of ammonia. After heating the feed water and drying, hydrogen (stream 1 ) is sent to the suction of the booster compressor of unit A, and the water condensate (stream 11 ) is returned to the water treatment unit F and added to the feed water (stream 12) of water treatment unit F.

[0068] The circulating gas (stream 13), which has given up its heat to produce steam, is sent from the steam generating unit E to the separation unit C. Here, gaseous ammonia is condensed into a liquid state. In the separation unit C, dissolved gases are separated from liquid ammonia and sent to the suction of the booster compressor of unit A (stream 5), and liquid ammonia (stream 7) in an amount about of 2685 kg / hour is sent to the warehouse. The separated circulation gas (stream 14) is returned to ammonia synthesis unit B.

[0069] The nitrogen-hydrogen mixture, compressed in unit A (stream 3), is sent to ammonia synthesis unit B, in which circulating catalytic synthesis of ammonia in a gaseous state is carried out at the pressure up to 20 MPa at the temperature range 380 °C to 510 °C.

[0070] Thus, in the presented ammonia production scheme, the use of all the heat that is released due to exothermic processes occurring during compression of gas flows and during the catalytic synthesis of ammonia is realized. At the same time, complete use of green hydrogen and cryogenic nitrogen for ammonia synthesis is achieved.

Claims

AMENDED CLAIMS received by the International Bureau on 12 June 2025 (12.06.2025)1 . A method for the synthesis of ammonia, comprising steps, where in: step a) a hydrogen (1 ) from an electrolyser (G) and a nitrogen (2) from a nitrogen production unit (D) are fed to a nitrogen-hydrogen mixture compression unit (A) and from there said mixture (3) is fed to an ammonia synthesis unit (B); characterized by the steps, where in step b) a circulation gas (6) from the ammonia synthesis unit (B) is fed to a steam generation unit (E), where the heat released during the synthesis reaction in the ammonia synthesis unit (B) is transferred by said circulating gas (6), is used to generate steam (10) for an electrolysis in the electrolyser (G); step c) a cooled circulation gas (13) from the steam generation unit (E) is fed to a separation unit (C), where ammonia (7) is separated from said circulation gas and said separated circulation gas (14) is fed back to the ammonia synthesis unit (B); step d) tank gases (5) from the separation unit (C) comprising hydrogen, nitrogen and gaseous ammonia separated from the separated liquid ammonia, are fed from the separation unit (C) to the nitrogen-hydrogen mixture compression unit (A) and are fed back to the ammonia synthesis unit (B); step e) heat of a steam-hydrogen stream (15) from the electrolyser (G), heat (4) generated during compression of the nitrogen-hydrogen mixture in the compressor stages of the nitrogen-hydrogen mixture compression unit (A) and heat generated during compression of hydrogen in the compressor stages of a hydrogen compressor, is used to heat in the steam generating unit (E) an incoming water (9) from a water treatment unit (F) fed to the steam generation unit (E); step f) liquid ammonia (7) is separated from the circulation gas (13) entering the separation unit (C) from the steam generation unit (E) using condensation at temperatures at an ambient environment between -40 °C and +50 °C; step g) water condensate (11 ) separated from the hydrogen at the outlet of the electrolyser (G) is fed to the water treatment unit (F).

2. Method according to claim 1 , wherein said electrolyser is SOEC-electrolyser.

3. Method according to any previous claim, wherein said mixture (3) fed to an ammonia synthesis unit has pressure from 10 MPa to 25 MPa (~99 to 250 at).

4. Method according to any previous claim, wherein the nitrogen is produced in the nitrogen production unit (D) by a cryogenic separation of the nitrogen from the ambient air.

5. Method according to any previous claim, wherein the condensation of the ammonia (7) at the ambient environment temperatures is carried out at temperatures between -20 °C and +40 °C.

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