Composite plant and method for operating the same

Abstract

The present invention relates to a combined plant comprising a heat pump circuit having a refrigerant evaporator designed to evaporate a refrigerant, a compressor designed to compress the refrigerant, the compressor fluidly connected to the refrigerant evaporator, a refrigerant condenser designed to condense the refrigerant, the refrigerant condenser fluidly connected to the compressor, a throttling device designed to reduce the temperature and pressure of the refrigerant, the throttling device fluidly connected to the refrigerant condenser and the refrigerant evaporator, and a heat generation plant having a cooling circuit with a refrigerant designed to heat the refrigerant during operation of the heat generation plant, the refrigerant fluidly connected to the refrigerant evaporator such that the refrigerant is heated in the refrigerant evaporator.

Description

[Technical Field]

[0001] The present invention relates to a combined plant comprising a heat pump circuit having a refrigerant evaporator designed to evaporate a refrigerant, a compressor designed to compress the refrigerant, the compressor fluidly connected to the refrigerant evaporator, a refrigerant condenser designed to condense the refrigerant, the refrigerant condenser fluidly connected to the compressor, and a throttling device designed to reduce the temperature and pressure of the refrigerant, the throttling device connected to the refrigerant condenser and the refrigerant evaporator fluidly connected to the throttling device.

[0002] The present invention further relates to a method for operating a combined plant, the combined plant having a heat pump circuit, in which a refrigerant is evaporated in a refrigerant evaporator, the evaporated refrigerant is supplied to a compressor, in which the temperature and pressure of the refrigerant are increased, the refrigerant is supplied after the compressor to a refrigerant condenser, the refrigerant is condensed in the refrigerant condenser, the refrigerant is supplied to a throttling device, the temperature and pressure of the refrigerant are reduced in the throttling device, and the refrigerant is supplied after the throttling device to a refrigerant evaporator.

[0003] The present invention relates generally to a refrigeration and heat pump cycle for electrolysis, for steam generation for direct air capture (DAC) technology, and for pressurized oxygen that can be used to generate electricity, the oxygen being produced in an electrolyzer.

[0004] Green hydrogen produced by electrolysis is considered a key element in achieving global decarbonization goals, since the entire value chain, from production to transportation and conversion to thermal or electrical energy, has the potential to be carbon-free. In electrolysis, so-called green energy, preferably from wind, solar, or hydropower, is used to split water molecules into hydrogen (H2) and oxygen (O2). However, in this method, only about 75% of the supplied electrical energy is converted into hydrogen (H2), while the remaining 25% is converted into heat.

[0005] For this reason, the electrolyzer must be cooled. This is a particularly difficult task when electrolysis is carried out in areas with high ambient temperatures, for example in the desert, since a significant amount of cooling water at a certain temperature is required. Lack of availability of cooling water can pose a risk to the operation of the electrolysis, as cooling is essential for the operation of the system.

[0006] In addition to the large-scale production of green hydrogen, direct air capture (DAC) can also be considered a key element in achieving decarbonization goals, as it can generate negative emissions. According to the International Energy Agency's (IEA) net-zero emissions scenario, the need for direct air capture of carbon dioxide (CO2) will rise to 1 gigaton per year to achieve carbon neutrality in 2050. However, because atmospheric CO2 concentrations are relatively low, averaging 400 ppm, the specific heat energy demand of DAC per ton of CO2 sequestered is very high. In the worst case, fossil fuels must be burned to provide this energy, resulting in additional CO2 emissions.

[0007] Large-scale green hydrogen production is a challenge. Because large-scale infrastructure for transporting hydrogen generally does not yet exist, most plants for producing green hydrogen are planned and operated at pilot scale near hydrogen consumers. Consumers, for example, are typically industrial users with cooling water at the required temperature. Furthermore, many of these processes require low- and medium-pressure steam, which can be generated with high-temperature heat pumps using waste heat streams from electrolysis. However, in hot and remote regions, cooling water at the required temperature and in the required quantity is often unavailable, and furthermore, there is generally no potential sink for the heat in question.

[0008] On the other hand, DAC is still considered economically unattractive due to its high specific energy demand per tonne of carbon dioxide (CO2) captured.

[0009] There is a need for improvement here. Summary of the Invention [Problem to be solved by the invention]

[0010] It is an object of the present invention to provide a cost-effective composite plant and method. [Means for solving the problem]

[0011] This problem is solved by a combined plant comprising a heat pump circuit having a refrigerant evaporator designed to evaporate a refrigerant, a compressor designed to compress the refrigerant, the compressor fluidly connected to the refrigerant evaporator, a refrigerant condenser designed to condense the refrigerant, the refrigerant condenser fluidly connected to the compressor, a throttling device designed to reduce the temperature and pressure of the refrigerant, the throttling device connected to the refrigerant condenser and fluidly connected to the refrigerant evaporator, and a heat generation plant having a cooling circuit with a refrigerant, the heat generation plant designed to heat the refrigerant during operation, the refrigerant being fluidly connected to the refrigerant evaporator so that the refrigerant is heated in the refrigerant evaporator.

[0012] The object is also achieved by a method for operating a combined plant, the combined plant having a heat pump circuit, in which a refrigerant is evaporated in a refrigerant evaporator, the evaporated refrigerant is fed to a compressor, the temperature and pressure of the refrigerant are increased in the compressor, the refrigerant is fed after the compressor to a refrigerant condenser, the refrigerant is condensed in the refrigerant condenser, the refrigerant is fed to a throttle device, the temperature and pressure of the refrigerant are reduced in the throttle device, and the refrigerant is fed after the throttle to the refrigerant evaporator, wherein a coolant flows through a refrigeration circuit of a heat generating plant, the coolant is heated in the heat generating plant, and the coolant is fluidly fed to the refrigerant evaporator such that the refrigerant is heated and cooled.

[0013] Advantageous developments are set forth in the dependent claims.

[0014] The present invention proposes the use of a counterclockwise refrigerant circuit, also known as a Joule cycle, which can be used on the one hand as a cooling circuit for electrolysis and on the other hand as a high-temperature heat pump for heating oxygen and generating steam.

[0015] The basic operating principle of the present invention is as follows: After a refrigerant absorbs the heat of the hot water leaving the electrolyzer, the refrigerant is evaporated, while the water is cooled and returned to the electrolyzer. The refrigerant is then compressed in a compressor, also called a refrigerant compressor, to a higher pressure and temperature level. This heat is then first used to heat pressurized oxygen generated as a by-product during electrolysis, while all of the latent heat is used to generate low-pressure steam in a condenser, also called a refrigerant condenser. The pressurized, hot oxygen is then expanded in an expansion turbine to generate electricity, after which it can be vented to the atmosphere or, if transport distances are appropriate, can be transported in significant quantities and used for various purposes (e.g., steelmaking, oxy-fuel combustion, or oxygen enrichment of seawater).

[0016] The low-pressure steam generated in the refrigerant condenser can be used to operate a direct air recovery system, which requires large amounts of low-pressure steam to filter carbon dioxide (CO2) from the air. Direct air recovery systems can be precisely sized to fit the electrolysis and heat pump, eliminating the need for external sources of heat and cold in this configuration.

[0017] The advantages of the plant according to the invention and the method according to the invention are the following: A refrigerant circuit is used to cool the electrolyzer and simultaneously to heat the oxygen for power generation and to generate the steam required for direct air recovery. By using heat from heat pumps, direct air capture needs are met by low pressure steam generation in remote areas. No external pumping of fresh water is required. A reliable cooling system for electrolysis in remote and high temperature areas. Oxygen produced as a by-product of electrolysis is used to generate electricity. Generate negative carbon dioxide (CO2) emissions through direct air capture. Green hydrogen production, already clean and carbon-neutral, will become even cleaner by producing not only a green fuel but also negative carbon dioxide (CO2) emissions.

[0018] The above-mentioned characteristics, features and advantages of the present invention, as well as the manner in which they are achieved, will become clearer and more understandable in conjunction with the following description of exemplary embodiments, which are illustrated in more detail by the drawings.

[0019] Components that are the same or have the same function are provided with the same reference numerals.

[0020] Exemplary embodiments of the present invention will now be described with reference to the drawings, which do not illustrate the exemplary embodiments to scale, and the drawings for illustrative purposes are shown in schematic and / or slightly distorted form. For supplementary teachings that are directly visible in the drawings, reference is made to the relevant prior art. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of a combined plant according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0022] 1 shows a combined plant 1 according to the present invention. The combined plant 1 includes a heat pump circuit, which will be described later.

[0023] A refrigerant, as is known in the art for heat pumps, circulates (counterclockwise in the diagram) in the circuit of the combined plant 1. The circuit begins with the refrigerant evaporator 2, into which it evaporates. The heat source required for this process comes from the heat generating plant 3.

[0024] This heat generation plant 3 is an electrolyzer, which is designed to produce hydrogen (H2) and oxygen (O2) from water by adding energy. The supplied energy can be based, for example, on renewable power generation units such as solar, wind or hydropower. The produced hydrogen (H2) is discharged via line 4. The supplied water is symbolically represented by line 5. The supplied energy is symbolically represented by line 6. The produced oxygen (O2) is symbolically represented by line 7.

[0025] The heat generation plant 3 requires a coolant, here water, which is added to the heat generation plant 3 via line 8. In this way, cooled water is added to the heat generation plant 3, where it is heated and returned to the refrigerant evaporator 2 via another line 9.

[0026] In the refrigerant evaporator 2, the thermal energy of the heated water from line 9 is used to evaporate the refrigerant, which is then cooled and returned to the heat generation plant 3 via line 8. The refrigerant evaporator 2 can therefore also be called a cooler for the coolant of the electrolyzer 3.

[0027] That is, refrigerant evaporator 2 is designed to evaporate a refrigerant. After refrigerant evaporator 2, the refrigerant flows via line 10 to compressor 11. Compressor 11 is designed to compress the refrigerant and is fluidly connected to refrigerant evaporator 2 via line 10.

[0028] In the compressor 11, the temperature and pressure of the refrigerant increase. The heated refrigerant flows through a precooler 13 via a line 12. Oxygen (O2) generated in the heat generation plant 3 also flows through this precooler 13 via a line 7. Here, in the precooler 13, the thermal energy of the refrigerant is transferred to the oxygen (O2), which increases the temperature of the oxygen (O2). The increased thermal energy of the oxygen (O2) is then converted into mechanical energy in an expander 14, which can then be converted into electrical energy by a generator 15.

[0029] The refrigerant that has passed through the precooler 13 is sent to a refrigerant condenser 16, where it is condensed. The condensate required for condensation comes from a line 17. This line 17 is fluidly connected to a carbon dioxide plant 18, which is designed to obtain carbon dioxide (CO2) 21 directly from the ambient air 19, and the steam 20 that can be produced in the refrigerant condenser 16 is fluidly connected to the carbon dioxide plant 18.

[0030] The complex plant 1 further comprises a throttling device 22 designed to reduce the temperature and pressure of the refrigerant, the throttling device being connected to the refrigerant condenser 16 and fluidly connected to the refrigerant evaporator 2. The throttling device 22 can be a Joule-Thomson valve (JT valve) or an expansion turbine.

[0031] The heat pump circuit (symbolically indicated by box 23 ) is closed again by returning the refrigerant to the refrigerant evaporator 2 .

Claims

1. A composite plant (1), comprising: a heat pump circuit having a refrigerant evaporator (2) designed to evaporate a refrigerant, and a compressor (11) designed to compress the refrigerant, the compressor (11) being fluidly connected to the refrigerant evaporator (2); and a refrigerant condenser (16) designed to condense the refrigerant, the refrigerant condenser (16) being fluidly connected to the compressor (11); a throttling device (22) designed to reduce the temperature and pressure of the refrigerant, the throttling device (22) being fluidly connected to the refrigerant condenser (16), and the refrigerant evaporator (2) being fluidly connected to the throttling device (22); The invention further comprises a heat generation plant (3) having a cooling circuit with a coolant, the heat generation plant (3) being designed so that the coolant is heated during its operation. In a complex plant, The coolant is fluidly connected to the refrigerant evaporator (2) such that the refrigerant is heated in the refrigerant evaporator (2). Complex plant.

2. 2. The composite plant (1) according to claim 1, wherein the refrigerant evaporator (2) is designed to cool the coolant.

3. 3. The composite plant (1) according to claim 1 or 2, wherein the heat generating plant (3) is designed as an electrolyzer.

4. A composite plant (1) according to claim 3, wherein the coolant is water.

5. 5. The composite plant (1) according to claim 3 or 4, further comprising a precooler (13) fluidly connected to the outlet of the compressor (11), wherein oxygen produced in the electrolytic cell is supplied to the precooler (13) so as to be heated by the precooler (13).

6. 6. The composite plant (1) according to claim 5, further comprising an expander (14) fluidly connected to the precooler (13), the expander being designed to convert thermal energy of the oxygen heated in the precooler (13) into mechanical energy.

7. 7. The composite plant (1) of claim 6, further comprising a generator (15) connected to the expander (14) to transmit torque.

8. 8. The composite plant (1) of claim 1, wherein the refrigerant condenser (16) is fluidly connected to the condensed water line (17) such that water flowing through the condensed water line (17) is converted into steam (20) in the refrigerant condenser (16).

9. The carbon dioxide plant (18) further comprises carbon dioxide (CO ) directly from the atmosphere. 2 9. The composite plant (1) of claim 8, wherein the vapor produced in the refrigerant condenser (16) is fluidly connected to the carbon dioxide plant (18).

10. 1. A method for operating a composite plant (1), the composite plant (1) having a heat pump circuit, wherein a refrigerant is evaporated in a refrigerant evaporator (2), the evaporated refrigerant is sent to a compressor (11), the temperature and pressure of the refrigerant are increased in the compressor (11), the refrigerant is sent after the compressor (11) to a refrigerant condenser (16), the refrigerant is condensed in the refrigerant condenser (16), the refrigerant is sent to a throttling device (22), the temperature and pressure of the refrigerant are reduced in the throttling device (22), the refrigerant is sent after the throttling device (22) to the refrigerant evaporator (2), a refrigerant flows through a refrigeration circuit of a heat generation system (3), and the refrigerant is heated in the heat generation system (3), the method comprising the steps of: fluidly sending the refrigerant to the refrigerant evaporator (2) such that the refrigerant is heated and the refrigerant is cooled.

11. 11. The method according to claim 10, wherein the heat generation system (3) is designed as an electrolyzer and water is used as coolant.

12. 12. The method according to claim 11, wherein a precooler (13) is arranged, and the refrigerant coming from the compressor (11) flows through the precooler, and oxygen produced in the electrolyzer is sent to the precooler (13) so that the thermal energy of the refrigerant heats the oxygen coming from the electrolyzer.

13. 13. The method of claim 12, wherein the heated oxygen is sent to an expander (14), which converts the thermal energy of the oxygen into mechanical energy.

14. 14. The method according to any one of claims 1 to 13, wherein the refrigerant condenser (16) is designed such that the thermal energy of the refrigerant is used to generate steam.

15. The steam is sent to a carbon dioxide plant (21), which produces carbon dioxide (CO 2 15. The method of claim 14, wherein the vapor produced in the refrigerant condenser (16) is fluidly connected to the carbon dioxide plant (18).

16. 16. The method of claim 15, wherein water produced in the carbon dioxide plant (18) is sent to the refrigerant condenser (16), and the water is converted to steam in the refrigerant condenser (16).

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