LU103261B1 - Device and method for the use of ammonia synthesis plants powered by renewable energies - Google Patents

Abstract

The present invention relates to a simplified process and a corresponding device with which waste heat from ammonia synthesis plants, in which the hydrogen required for the production of ammonia is produced by means of water electrolysis, can be further utilized with the aid of low-pressure steam. In this process and the corresponding device, low-pressure steam with a temperature of less than 200°C and a pressure of 5 to 15 bar is generated from the waste heat of the ammonia synthesis plant, which can be used for further uses. By using low-pressure steam, significant economic advantages can be realized compared to the conventional use of medium-pressure steam when operating the process with intermittent power sources. The present invention further relates to devices designed to carry out such processes and to plants which have a plant section for producing ammonia and a plant section for utilizing waste heat from this plant section, wherein this second plant section is formed from the specified device.

Description

230307P00L4/ 103261 thyssenkrupp Uhde GmbH thyssenkrupp AG

Device and method for the use of ammonia synthesis plants powered by renewable energies

Description

The present invention relates to a simplified process by which waste heat from ammonia synthesis plants, in which the hydrogen required for the production of ammonia is produced by means of water electrolysis, can be further utilized with the aid of low-pressure steam. The present invention further relates to devices designed to carry out such processes and to plants comprising a plant section for

Production of ammonia and a plant part for utilizing waste heat from this plant part, wherein this second plant part is formed from the specified device.

State of the art

Ammonia is an essential element for the production of fertilizers

Substance, and is now produced on a multi-ton scale in large-scale plants. The Haber-Bosch process is generally used, in which nitrogen and hydrogen are directly reacted to form ammonia.

In plants for the production of ammonia according to the Haber Bosch process, a large amount of waste heat is generated, since the reactant gases nitrogen and

Hydrogen must be heated to high temperatures of 400 to 500°C for the reaction to be optimally effective. Since the reaction is exothermic (see below),

Reaction equation) the mixture heats up even further during the reaction and must subsequently be used to condense the ammonia formed and to

Separation of residues of the reactant gases can be cooled to significantly lower temperatures.

230307P0UUW 103261 2

N, +3H; > 2NH; AH = -92.28 kJ/mol (AH298x = -46.14 kJ/mol)

Cooling is usually done using water as a cooling medium, which absorbs the heat from the gas mixture, which can then be used in further processes.

In today's conventional plants, this utilization occurs by heating water as a cooling medium to temperatures of over approximately 450°C in order to operate a steam turbine and a generator for electricity production. For this purpose, the ammonia synthesis plant, for example, is thermally coupled to the waste heat system in such a way that the gas flowing out of the ammonia synthesis plant first passes through a heat exchanger, in which part of the

Heat is transferred to the water and then led to a position upstream in the waste heat system, where a second

Heat exchanger residual heat can be transferred to the water. The heat transferred to the water at two points is used to heat the water in two

stages to the temperature required to operate the steam turbine.

In order to effectively use the temperature from the ammonia synthesis plant, the waste heat system is designed to operate at a higher temperature in the

The steam is designed for temperatures between approximately 250°C and 300°C at a system pressure of approximately 40 bar (medium pressure steam or MD steam) or 300°C and 350°C at a system pressure of approximately 125 bar (high pressure steam or HP steam). If the steam is superheated with the hot gas from the ammonia converter,

Temperatures even reach about 400°C. If other heat sources are used, e.g. hot

Exhaust gas from the primary reformer in a conventional ammonia plant, the temperatures of the superheated steam reach over 500°C. Therefore, part of the waste heat system in the area between the heat exchanger and the

Steam turbine must be designed for higher temperatures and pressures.

Such a conventional (i.e. usually powered by natural gas)

For economical operation, the plant design is based on a constant

This represents a relevant factor for the operation of corresponding plants with renewable energy sources such as solar or wind energy.

problem (in the course of changing annual precipitation distributions

230307P0UUW 103261 3 can also affect hydropower), as this is not always evenly distributed.

are available, but the power generation by steam generators requires a constant energy supply; if this is not available, the

Steam generator is shut down and the cooling medium of the

Waste heat system may need to be cooled in another way. On the other hand,

On the other hand, depending on the location, operating an ammonia synthesis plant with renewable energy, and in particular with solar and/or wind energy, can be economically very advantageous. This is because, on the one hand, rising prices for conventionally generated energy are to be expected in the course of the decarbonization of the global economy, and, on the other hand, the costs of solar and wind energy have fallen sharply in recent years. The costs for plant components used to generate electricity in conventional ammonia synthesis plants are highly detrimental if the plant cannot be operated at 100% full load. Against this background, there is a need for a cost-effective process and a corresponding device for utilizing the

Waste heat from ammonia synthesis plants, which can be used even in the case of unsteady

Utilisation of the plant can be operated economically overall during periods of low demand or times of the year when renewable energy is less available.

Another goal in the synthesis of ammonia is to obtain the

The hydrogen required for the synthesis of ammonia is not produced from methane (because conventional technology also releases carbon dioxide), but rather through water electrolysis. Obviously, plants in which the hydrogen required for ammonia synthesis is produced via hydrogen electrolysis require a different structure upstream of the unit in which the ammonia is produced than conventional plants, because the entire process path to

Generation of make-up gas (hydrogen-nitrogen mixture with inert

Argon and methane) from methane and water is not needed, but by

Water electrolysis units are replaced. In this way (with simultaneous

Using renewable electrical energy, an ammonia synthesis plant can be operated entirely “green” or without producing carbon dioxide.

The present invention addresses the problem of providing such largely or completely carbon dioxide-neutral

230307P0UUW 103261 4

Ammonia synthesis plants, or the economic use of waste heat from such plants.

Description of the invention

To solve the problems described, the invention proposes

Waste heat from an ammonia synthesis plant in which the required for the production of the

The hydrogen required for the production of ammonia is produced by means of water electrolysis, not via a medium-pressure or high-pressure steam system and a downstream steam turbine, but via a

Low-pressure steam system in which the “cooling water” is used with significantly lower

temperature and lower pressure in the cooling system. This

Cooling water is then no longer available for the generation of electricity.

It is available but can be used as a heat source in other technical processes, thus saving costs for the plant components used to generate electricity. Furthermore, the use of low-pressure steam instead of medium-pressure steam allows the entire waste heat recovery plant to be designed for the lower pressure, which also entails considerable savings.

Cost savings compared to a conventionally designed system.

Accordingly, a first aspect of the present invention relates to a process for the utilization of waste heat from ammonia synthesis plants in which the

The production of ammonia required hydrogen with the help of a

Water electrolysis is produced, using waste heat from the

Ammonia synthesis plant is transferred to water as a cooling medium via a heat exchanger, and the water is heated to a temperature of less than 200°C at a pressure in the range of 5 to 15 bar. Preferably, the water is used in this process as steam, i.e. at a

Temperature of more than 100°C. Water as a cooling medium has the

Advantage of a particularly high heat capacity and a particularly high

evaporation enthalpy, so that a comparatively large amount of heat can be absorbed from the system, and on the other hand, water is readily available in most cases and, compared to other solvents, also from an ecological point of view.

Visibility is harmless.

230307P0UUW 103261

The statement “at a pressure in the range of 5 to 15 bar” is to be understood as meaning that this pressure indicates the maximum pressure under which the water is for the heating process. This is usually

Pressure is reached particularly before and when the water enters the heat exchanger 5 (for example in the pipe area between a boiler water pump and the heat exchanger, in which it is heated as a result of the heat absorption by the

Water to evaporate the water and to a slight

Pressure drop (usually in the range of 0.5 to 2 bar) can occur.

Pressure specification therefore refers to the pressure before or directly at the water entry into the heat exchanger.

In contrast, the temperature “less than 200°C” refers to the maximum

Temperature to which the water is heated in the heat exchanger and the

The water exits the heat exchanger.

The term “heat exchanger” in the context of the information given here means

Invention a device in which thermal energy (heat) from a

Medium is transferred to another medium without the media mixing. This is achieved, for example, by transferring the media with opposite flow directions through thermally coupled but

Passage of material through pipes shot through, whereby the warmer medium cools down and the colder medium heats up by absorbing energy released by the warmer medium.

For the method according to the invention, it is preferred if the cooling medium downstream of the heat exchanger is used to heat another medium, whereby cooled cooling medium is produced in this way.

The term “downstream” refers to a system in which a material is conveyed from one side to the other, or a recirculating system in which a

material circulates. In this context, “downstream” refers to a point in

Flow direction from the circulating material to a later

The point passed at a given time is considered the reference point. Similarly, the term "upstream" refers to a point passed by the material at an earlier time than the reference point.

230307P0UUW 103261 6

The method is further preferably designed so that the cooling medium, instead of heating the further medium, can also be heated with the aid of a

Such a design can be such that the cooling medium is fed via a pipe to the heat exchanger for

Heating of another medium and via a separate line to a

Cooling water system, whereby the supply of the cooling medium can be switched via a corresponding distributor, or a heat exchanger, which can also be used as a cooling water system. The "switching" is preferably carried out depending on the amount of heat that is transferred to the cooling medium in the heat exchanger during the process, whereby

If a threshold is exceeded, the procedure is conducted in such a way that the

Cooling medium is supplied to the cooling water system and when the

threshold value, the cooling medium is fed to the heat exchanger to heat another medium.

The “cooling water system” refers to a system that extracts heat from the

The cooling medium is transferred to the cooling water without the heat being used for further purposes. Examples of suitable cooling media include river water, water from a larger reservoir that can release absorbed heat to the environment, or a cooling tower system or similar. Such systems are known to those skilled in the art and can be selected accordingly based on the specific local conditions.

In a preferred embodiment, the heating of the further medium or the removal of the waste heat from the ammonia synthesis plant into the

Cooling water system in the process according to the invention is designed separately, i.e. they take place in separate parts of the system.

Further possibilities for the use of the cooling medium as a heat source include uses that are effective within the specified process, as well as external uses in which the heat is used for purposes that are not related to an ammonia synthesis plant or a waste heat system of such a plant. A possible use within the specified process is, for example, the (pre-)heating of demineralized water in a deaerator through which the cooling medium passes during the process according to the invention. Other internal

230307P0UUW 103261 7

Uses include, for example, use in a stripper during

Residual gas scrubbing, especially for preheating the column bottom in

Reboiler (see description below), or in the context of a

Adsorption chiller for condensing product ammonia and the

Regeneration of the cooling brine or in air conditioning systems.

External uses for which the cooling medium can be used include the preheating of electrolysis cells used for alkaline

Water electrolysis, heating or preheating of

Water for solid oxide electrolysis (SOEC = solid oxide electrolyzer cell), for

Heating of water in the context of a water desalination plant, in particular in the context of multi-stage flash evaporation (where the seawater can be heated to a temperature of e.g. 115°C), for the generation of external steam or district heating, or for salt production.

In a particularly preferred embodiment, the cooling medium is used for

Heating of water in the context of water desalination, especially

Seawater is used, which is particularly preferred as Multistage Flash

Evaporation or multi-effect distillation. Particularly preferably, the water or seawater desalination is designed as a process referred to as “boosted multi-effect distillation” or “flash-boosted multi-effect distillation.” In a particularly preferred embodiment, the cooling medium is used in a direct air capture process (i.e., a

Process in which CO, is removed directly from the air, and the cooling medium is needed for the regeneration of the absorbent that absorbs the CO,).

In a further preferred embodiment, the cooling medium is used for

Heating of electrolysis cells in an alkaline water electrolysis plant, or as external steam, district heating, or other heat source. In yet another preferred embodiment, the cooling medium is used for (pre)heating demineralized water in a deaerator used in the context of utilizing waste heat from ammonia production plants.

230307P0UUW 103261 8

In the process according to the invention, it is further preferred if the water as cooling medium in the heat exchanger is heated to a temperature in the range of 150 to 190°C, preferably 158 to 189°C, more preferably 164 to 180°C and most preferably 167 to 176°C. Furthermore, or alternatively, it is preferred that the water as cooling medium in the heat exchanger is heated to a

Pressure of 6 to 12 bar and preferably 7 to 10 bar and most preferably 7.5 to 9 bar.

The water as a cooling medium is furthermore used in the context of the inventive

The process is carried out in a cycle, i.e. the water is recycled in several

circuits, whereby it is heated in the heat exchanger in each circuit and the heat energy absorbed in it is then transferred to another

medium or discharged via a cooling water system.

When operating the cooling system, the water should be as salt-free as possible in order to

To prevent salt deposits in the system, which can form as a result of water evaporation, it is advisable to reuse the water as a cooling medium. This avoids the high technical and energy costs associated with water treatment and desalination.

Within the cooling circuit, the water is conveniently pumped. It may also be useful to conduct the water as a cooling medium after heating another medium through a condenser, and then through a condensate polisher and a

Deaerator. However, a condenser can also be omitted, for example, if the cooling medium is heated by another

So much heat has been removed from the medium that condensation is no longer necessary.

In the context of the invention described here, a condensate polisher is understood to mean a device in which condensed water from a

Steam cycle is filtered. A condensate polisher is usually filled with a polymeric ion exchange resin, which can remove ions from condensed water. After passing through these units, the

Cooling medium water with the help of the pump arranged in the circuit, which is in the

230307P0UUW 103261 9

Usually positioned downstream of the vent, it is returned to the heat exchanger.

As mentioned above, the main advantage of the

The procedure is that the procedure is the economic operation of a

Ammonia synthesis plant with renewable energies that are not continuously available in the same quantity throughout the year, and in particular with

Wind and/or solar energy is permitted. Therefore, in a preferred embodiment, the process is carried out using electricity from corresponding renewable

Energies and in particular electricity from wind and/or solar.

A “renewable energy” that is continuously supplied in the same amount throughout the year

Available energy sources include hydropower or biogas; accordingly, the process is preferably not operated with hydropower or biogas. Depending on the interpretation in different countries, nuclear power can also be considered "renewable energy."

Another aspect of the present invention relates to a device for

Use of waste heat from ammonia synthesis plants in which the required

The production of ammonia required hydrogen with the help of a

Water electrolysis, wherein the device comprises a heat exchanger 4 in which heat from an ammonia plant is transferred to water as a cooling medium, and wherein the device is designed for operation at a temperature of less than 200°C and a pressure of 5 to 15 bar. The statement "is designed for operation at a temperature of less than 200°C and a pressure of 5 to 15 bar" means that the

The system is adapted to the corresponding temperatures and pressures and can be operated safely under these conditions, but on the other hand cannot be operated safely at significantly higher temperatures and pressures, or is not designed for such conditions. Since higher temperatures and pressures place significantly higher demands on the material from which the device is constructed, the investment costs for such

Devices can be significantly reduced compared to conventional devices.

Another advantage is that the lower pressure and lower

temperatures require less complex boiler feed water treatment. In a preferred embodiment, the inventive

Device further comprises a further heat exchanger 14, via which heat

230307P0UUW 103261 10 from the cooling medium to another medium. For this purpose, the heat exchanger 14 is fluid with the heat exchanger 4, i.e. the cooling medium can be transferred (directly or indirectly via intermediate

device elements) via corresponding lines from the heat exchanger 4 to the

heat exchanger 14. The statements made in the context of the process described above apply analogously to this cooling medium.

Cooling medium can then be used to heat demineralized water in a deaerator, to heat electrolysis cells in an alkaline

water electrolysis, seawater desalination, or the generation of external steam or district heating, or for any of the other uses mentioned above.

Alternatively or additionally, it is preferred if the device is

Circuit for the cooling medium is designed, wherein the cooling medium after the

Passing through heat exchanger 4, in which heat from an ammonia plant is transferred to

Water is transferred as a cooling medium, and the heat exchanger 14 via a

Pump 3 is circulated and the device is located in front of the

Heat exchanger 14 has a switchable T-junction 15, via which the

Cooling medium to the heat exchanger 14 and/or via a cooling unit 16 to the

pump can be returned.

The cooling unit is, as stated above, a unit in which the

The cooling medium is cooled without the heat energy being used for other purposes. While energy is lost unused in this way, this may be economically acceptable if the alternative is that expensive energy utilization devices cannot be operated economically.

In the cooling unit, the water used as cooling medium can be brought into contact with “cooling” water, which has a lower temperature, via a thermally conductive barrier, whereby the water used as cooling medium

Water can transfer thermal energy to the “cooling” water and to this

A possible source of "cooling" water as a receiver of thermal energy is, for example, river water or water from a larger reservoir that can release absorbed heat to the environment.

230307P0UUW 103261 11

Alternative cooling units include, but are not limited to,

Cooling water pumps, cooling tower systems, or air coolers.

For the specified device designed as a circuit for the cooling medium, it is further preferred if it has a

Condenser 8, a condensate polisher 10 and a vent 12, through which the cooling medium is fed to the pump 3. In another preferred

In this embodiment, the device does not have a capacitor 8, i.e. on the

Heat exchanger 14, the water used as cooling medium is fed directly to the

Condensate polisher 10. For this embodiment, it is furthermore expedient if the vent is arranged downstream of the condensate polisher. Between these, a unit for preheating the

Water. If the device contains a condenser 8, it is further preferred if this is arranged upstream of the condensate polisher 10 and downstream of the heat exchanger 14 in the device. Here, too, the individual device elements are connected to one another by corresponding lines.

In yet another aspect, the present invention relates to a plant comprising a plant section for producing ammonia, in particular from hydrogen and nitrogen, and a plant section for utilising waste heat from the

Plant section for the production of ammonia, wherein the plant section for

Utilization of waste heat as a device as described above and thermally connected to the plant section for the production of ammonia. In this plant, the plant section for the production of

Ammonia a water electrolysis device to generate the required

The hydrogen required for ammonia synthesis is produced. Corresponding systems are described, for example, in WO 2023/114890 A1 or US 2021/0340017 A1.

In a particularly preferred embodiment, the plant section for producing ammonia is an ammonia synthesis plant according to the Haber-Bosch process, in particular with a connection to a

Power supply designed to supply wind and/or solar power and/or connected to corresponding wind and/or solar systems.

230307P0UUW 103261 12

In order to use the waste heat from the plant section for producing ammonia, the plant in a preferred embodiment has a further (additional) plant section, which is in particular selected from a

Plant section for alkaline water electrolysis, a plant section for

Seawater desalination, or a plant component for the generation of external

Steam or district heating. The term “external steam” here means that the steam generated in this part of the plant is used for external

use and can be supplied to an external user (i.e. not integrated into the system) via an appropriate supply system.

In conventional ammonia synthesis plants, ammonia is recovered from the plant's flash gas in a "residual gas scrubbing" process, which is carried out by washing with water. The resulting ammonia-laden water is then heated in a stripper so that the

Ammonia gas (about 80 vol% NHz) leaves the stripper via the column head and the ammonia-depleted wash water leaves the column bottom.

Heating of the column bottom to about 216°C is carried out with the

Medium pressure steam (MD steam, about 40 bar and 400°C) in a separate

Heat exchanger (reboiler), where after the reboiler there is another

Condensate separator is connected in series. However, such use requires a comparatively high water temperature. Since corresponding

Water is no longer available in the plant concept according to the invention, it is preferred if this part of the stripper is equipped with an electrically heated

System is operated. As mentioned above, however, the cooling medium heated in the device according to the invention can still be

Preheating of the process condensate, which the process condensate passes through before it reaches the part of the stripper in which process condensate is used as

Column sump is heated.

For the device specified above and the system comprising such a device, it is preferred if it is powered by a power grid that includes one or more renewable energy sources. "Powered" in this case refers to the fact that the power grid supplies the device, and in particular the system, with the power required for its operation.

It is preferred if the power grid is at least 70%, more preferably at least 80%, and even more preferably at least 90%

230307P0UUW 103261 13 is supplied by renewable energy sources. In one embodiment, the renewable energy sources are at least 70%, in particular at least 80%, and most preferably at least 90% by intermittent renewable energy sources (i.e. those that are not available around the clock and via a

available in the same quantity throughout the operating year).

Intermittent renewable energy sources are especially (but not exclusively) wind and solar. By using such renewable

Energy, the advantages of the device according to the invention and the corresponding system are best exploited.

In the following, the present invention is further illustrated and explained with reference to the accompanying drawings 1 and 2.

Figure 1 shows a waste heat system 1 for an ammonia synthesis plant 2 according to the prior art. The waste heat system comprises a KSW-

Pump (3, "KSW" = boiler feed water), and in the flow direction of the cooling medium (here indicated by arrows) a waste heat boiler 4 and a heat exchanger 5, which in the context of the device shown is designed as a steam superheater.

In the waste heat boiler, the water is heated as a cooling medium to a temperature of about 260°C, in the steam superheater the temperature is further increased to about 470°C. The superheated steam thus produced is fed to a

The steam turbine 6 is coupled to the generator 7 and used to generate electricity. The steam derived from the steam turbine and partially cooled

Steam is then fed to a condenser 8 and, via a subsequent condenser pump 9, to a polishing unit 10 and subsequently to a

preheater 11, from which it returns to pump 3 via a vent 12. Part of the superheated steam is removed in the stripper unit of the

Ammonia synthesis plant 2 and in particular in the part of the stripper where

Process condensate is heated as column bottom (“reboiler”, 13).

Part of the water discharged from the steam turbine can also be fed directly to the

Vent 12. Such a system is used, for example, as

Medium pressure system with a working pressure of approximately 40 to 80 bar.

The pressure in the turbine is reduced from 45 bar or 80 bar to 8 bar, for example.

Figure 2 shows a waste heat system 1 according to the above-described

In this system, as in the prior art,

230307P0UUW 103261 14

Water is used as a cooling medium in a circuit driven by a waste heat recovery pump 3. In contrast to the state of the art, however, this water only passes through a heat exchanger 4 designed as a waste heat boiler, in which the water is heated to a temperature of approximately 152°C (at a pressure of, for example, 5 bar). Any higher energy densities that may arise due to the lower

The fact that the temperature of the cooling medium must be dissipated is taken into account by appropriately dimensioning the ratio of heating medium (waste heat from ammonia production) to cooling medium.

After the heat exchanger, the water used as cooling medium (in the form of water vapor) is fed to a T-junction 15, from which it is

Heat exchanger 14 or a cooling unit. In

Heat exchanger 14 transfers the heat from the cooling medium to another

medium which can subsequently be used, for example, to operate a

Seawater desalination plant (not shown in Figure 2). Depending on how much energy is extracted from the water in the heat exchanger, a condenser 8 can be connected downstream to

As in a conventional waste heat system, the water thus obtained then passes through a polishing unit 10 and then a preheater 11, from which it is led via a vent 12 to the

Pump 3 returns.

The water cooled in the cooling unit is also fed to the vent 12.

The described waste heat system 1 corresponds to the inventive

Device as described above, while the specified

Such a device and at least one additional

Ammonia synthesis plant 2.

As can be seen from the above specific description, in the device concept according to the invention, several system components that are present in a conventional waste heat system can be omitted or can be designed more cost-effectively due to the other conditions of the process.

In particular, the energy required for electricity generation can be eliminated

Units such as the steam superheater, the steam turbine itself and the generator,

230307POLUWJ103261 15 and the downstream condensate pump. A reboiler for the stripper can be replaced by a suitable electrically operated heating device.

In some cases, the condenser downstream of the turbine can also be omitted. In this case, the elimination of the turbine is the most cost-effective.

Weight, since it must be switched on or off when partial load falls below a certain limit (approximately 22%), which requires corresponding preparation and costs. Regular costs for turbine maintenance can also be eliminated.

In addition, the heat exchanger (waste heat boiler), the waste heat pump, and the waste heat and steam lines can be designed more cost-effectively due to the lower temperatures and pressures. This is offset by additional investments for a

Cooling system and for an electric heating system for the reboiler of the

Strippers, but the overall costs for the waste heat system are still significantly lower.

As the following calculation shows, this also applies if the costs for the electricity not generated are included in the calculation.

For the calculations, the following key data of a real project are used:

Based on:

Plant data: 3400 tons of ammonia per day (tato), generator capacity 27 MW,

Electricity price from renewable energy (wind farm) 18.3$/MWh

Total operating hours when supplied by wind power: 8760 h, of which 272 h at partial load of 1%, 203 h at partial load of 1% to 8%; 2650 h at full load and 5635 h at a power surplus (here it is assumed that in times of

Electricity surplus (the ungenerated electricity costs nothing)

During the total operation of the plants, 27 MW x 2650 h = 71550 MWh of electricity are generated. If this generation is eliminated, the result is

Electricity price in loss of about $1.3 million. This is offset by savings in costs for unnecessary or differently designed components, investment and

Interest costs of approximately $29 million are offset by interest expenses.

Savings through possible use of waste heat (e.g. for

230307P0UUW 103261 16

Seawater desalination), nor costs for the larger pumps required for the low-pressure system, possibly additional space for a cooling tower that must be provided, and any necessary

Low-pressure steam condenser. However, these costs are estimated to be small compared to the savings.

The calculation shows that even without taking into account financial advantages from the use of low-pressure steam (obvious mostly for seawater desalination), there is a clear financial advantage for the system according to the invention if the electricity price is low and over many

hours a year there is an electricity surplus (e.g. due to appropriate

Dimensioning of the wind turbines used for their operation). With a

Heat utilization of low-pressure steam (34.5 MW for the proposed

plant), the CAPEX of a wind-powered plant can be

ammonia synthesis plant, possibly even without the

OPEX increased. Using low-pressure steam beyond 34.5 MW would not only further reduce CAPEX, but also reduce OPEX. A further significant advantage is the significant simplification of

System that reduces maintenance costs and the risk of failure of the

Reduce investment.

List of reference symbols 1 Waste heat device 2 Ammonia synthesis plant 3 (KSW) pump 4 Waste heat boiler 5 Heat exchanger 6 Steam turbine 7 Generator 8 Condenser 9 Condensate pump 10 Polishing unit 11 Preheater for demineralized water

230307P0LW103261 17 12 Deaerator 13 Reboiler from the stripper (component of the ammonia synthesis plant) 14 Heat exchanger for heating additional medium 15 T-junction 16 Cooling unit

Claims (14)

230307P00L4} 103261 claims 1. A process for the utilization of waste heat from ammonia synthesis plants in which the hydrogen required for the production of ammonia is produced by means of water electrolysis, wherein waste heat from the ammonia synthesis plant is transferred via a heat exchanger to water as a cooling medium, wherein the water is heated or adjusted to a temperature of less than 200°C and a pressure of 5 to 15 bar. 2. Method according to claim 1, characterized in that the cooling medium downstream of the heat exchanger is used to heat another medium, whereby cooled cooling medium is produced, and the method is preferably designed so that the cooling medium can also be cooled with the aid of a cooling water system instead of heating the other medium. 3. Process according to claim 2, characterized in that the cooling medium is used for heating demineralized water in a deaerator, and/or for heating electrolysis cells in an alkaline water electrolysis, and/or for seawater desalination, and/or for direct air capture and/or as external steam, district heating or other heat source. 4. Process according to one of claims 1 to 3, characterized in that the water is heated or adjusted to a temperature in the range of 150 to 190°C, preferably 158 to 189°C, more preferably 164 to 180°C, more preferably 167 to 176°C and/or a pressure of 6 to 12 bar, preferably 7 to 10 bar, more preferably 7.5 to 9 bar. 5. Method according to one of the preceding claims, characterized in that the water is circulated as a cooling medium by means of a pump, and wherein the water is preferably passed through a condenser, a condensate polisher and a vent after heating another medium before the water is returned to the heat exchanger. 230307P0UUW 103261 2 6. Process according to one of the preceding claims, characterized in that the ammonia synthesis plant is operated with electricity from renewable energies, in particular with electricity from wind and/or solar energy. 7. Device (1) for utilizing waste heat from an ammonia synthesis plant (2), in which the hydrogen required for the production of ammonia is produced by means of water electrolysis, the device comprising a heat exchanger (4) in which heat from an ammonia synthesis plant (2) is transferred to water as a cooling medium, the device (1) being designed to operate at a temperature of less than 200°C and a pressure of 1 to 20 bar. 8. Device (1) according to claim 7, characterized in that the device further comprises a heat exchanger (14) via which heat can be transferred from the cooling medium to another medium and which is fluidly connected to the heat exchanger (4). 9. Device (1) according to claim 7 or 8, characterized in that the device is designed as a circuit for the cooling medium, wherein the cooling medium can be circulated via a pump (3) after passing through the heat exchanger (4) and the heat exchanger (14), and wherein the device has a switchable T-junction (15) upstream of the heat exchanger (14), via which the cooling medium can be returned to the heat exchanger (14) and/or to the pump via a cooling unit (16). 10. Device according to claim 9, characterized in that the device has a condenser (8), a condensate polisher (10) and a vent (12) downstream of the heat exchanger (14), via which the cooling medium is led to the pump (3). 11. Plant comprising a plant part for producing ammonia (2) from hydrogen and nitrogen, wherein the plant part for producing ammonia comprises a water electrolysis device for generating the hydrogen required for the 230307P0LW103261 3 ammonia synthesis required hydrogen, and a plant part for utilizing waste heat from the plant part for producing ammonia, wherein the plant part is designed as a device according to claim 7 and is thermally coupled to the plant part for producing ammonia. 12. Plant according to claim 11, further comprising a plant part for alkaline water electrolysis, for seawater desalination, or for the generation of external steam or district heating. 13. Plant according to claim 11 or 12, wherein the plant section for producing ammonia comprises a stripper in which the ammonia-laden water in the column bottom is electrically heated for the purpose of recovering the ammonia from the flash gas from the ammonia synthesis. 14. Device according to one of claims 7 to 10 or plant according to one of claims 11 to 13, wherein the device or plant is powered by a power grid comprising one or more renewable energy sources, preferably wherein the power grid is powered by at least 90% renewable energy sources.