Combination system and method for operating a combination system

Abstract

The invention relates to a combination system (1) comprising a heat pump circuit having a refrigerant evaporator (2), which is designed for evaporating a refrigerant, furthermore comprising a compressor (11), which is designed for compressing the refrigerant, wherein the compressor (11) is connected in terms of flow to the refrigerant evaporator (2), furthermore comprising a refrigerant condenser (16), which is designed for condensing the refrigerant, wherein the refrigerant condenser (16) is connected in terms of flow to the compressor (11), furthermore comprising a restrictor device (22), which is designed for reducing the temperature and the pressure of the refrigerant, wherein the restrictor device (22) is connected to the refrigerant condenser (16), wherein the refrigerant evaporator (2) is connected in terms of flow to the restrictor device (22), furthermore comprising a heat generation system (3) having a cooling circuit with a cooling medium, wherein the heat generation system (3) is designed in such a way that, during the operation, the cooling medium can be heated, wherein the cooling medium is connected in terms of flow to the refrigerant evaporator (2) in such a way that the refrigerant can be heated in the refrigerant evaporator (2).

Description

[0001] Description

[0002] Combined plant and method for operating a combined plant

[0003] The invention relates to a combination system comprising a heat pump circuit having a refrigerant evaporator which is designed to evaporate a refrigerant, further comprising a compressor which is designed to compress the refrigerant, wherein the compressor is fluidically connected to the refrigerant evaporator, further comprising a refrigerant condenser which is designed to condense the refrigerant, wherein the refrigerant condenser is fluidically connected to the compressor, further comprising a throttle device which is designed to reduce the temperature and the pressure of the refrigerant, wherein the throttle device is connected to the refrigerant condenser, wherein the refrigerant evaporator is fluidically connected to the throttle device.

[0004] The invention further relates to a method for operating a combination system, the combination system having a heat pump circuit, a refrigerant being evaporated in a refrigerant evaporator, the evaporated refrigerant being fed to a compressor, the temperature and pressure of the refrigerant being increased in the compressor, the refrigerant being fed to a refrigerant condenser downstream of the compressor, the refrigerant being condensed in the refrigerant condenser, the refrigerant being fed to a throttling device, the temperature and pressure of the refrigerant being reduced in the throttling device, the refrigerant being fed to the refrigerant evaporator downstream of the throttling device.

[0005] The invention generally relates to a refrigeration and heat pump circuit for electrolysis and steam generation for a Direct Air Capture (DAC) process and pressurized oxygen which can be used to generate electricity, wherein the oxygen was generated in an electrolyzer.

[0006] Green hydrogen produced through electrolysis is considered a key factor in achieving global decarbonization goals, as the entire value chain, from production and transport to conversion into heat or electrical energy, can be CO2-free. In an electrolysis process, electrical energy, preferably so-called green energy from wind, solar, or water, is used to split a water molecule into hydrogen (H2) and oxygen (O2). However, in this process, only approximately 75% of the input electrical energy is converted into hydrogen (H2); the remaining 25% is converted into heat.

[0007] For this reason, the electrolysis process requires cooling. This can be particularly challenging when electrolysis is carried out in areas with high ambient temperatures, such as deserts, as a corresponding amount of cooling water at a specific temperature is required. The unavailability of cooling water could jeopardize the operation of the electrolysis process, as cooling is essential for the system's operation.

[0008] In addition to the large-scale production of green hydrogen, direct air capture (DAC) is also considered an important factor in achieving decarbonization goals due to its potential for generating negative emissions. According to the International Energy Agency's (IEA) net-zero emissions scenario, the demand for direct air capture will increase to 1 gigaton of carbon dioxide (CO2) per year to achieve climate neutrality in 2050. However, due to the relatively low carbon dioxide (CO2) concentration in the ambient air, averaging 400 ppm, DAC has a very high specific heat energy demand per ton of captured carbon dioxide (CO2). In the worst case, fossil fuels must be burned to provide the energy, leading to additional carbon dioxide (CO2) emissions.

[0009] The large-scale production of green hydrogen is a challenge. Most green hydrogen plants are planned and operated on a pilot scale close to the hydrogen consumer, as large-scale infrastructure for hydrogen transport is usually not yet in place. Consumers include industrial customers who usually have access to cooling water at the required temperature. In addition, many of these processes require low-pressure and medium-pressure steam, which can be generated with a high-temperature heat pump using the waste heat stream from electrolysis. However, in hot and remote areas, cooling water of the required temperature and quantity is often not available, and there is usually a lack of a potential sink for the heat in question.

[0010] On the other hand, DAC is still considered economically unattractive due to the high specific energy demand per ton of captured carbon dioxide (CO2).

[0011] There is a need for improvement here.

[0012] The invention aims to offer a combined system and method that offers a cost advantage.

[0013] This object is achieved by a combination system comprising a heat pump circuit having a refrigerant evaporator which is designed to evaporate a refrigerant, further comprising a compressor which is designed to compress the refrigerant, wherein the compressor is fluidically connected to the refrigerant evaporator, further comprising a refrigerant condenser which is designed to condense the refrigerant, wherein the refrigerant condenser is fluidically connected to the compressor, further comprising a throttle device which is designed to reduce the temperature and the pressure of the refrigerant, wherein the throttle device is connected to the refrigerant condenser, wherein the refrigerant evaporator is fluidically connected to the throttle device, further comprising a heat generation system having a cooling circuit with a cooling medium, wherein the heat generation system is designed in such a way,that the cooling medium can be heated during operation, wherein the cooling medium is fluidly connected to the refrigerant evaporator in such a way that the refrigerant in the refrigerant evaporator can be heated.,

[0014] The object is also achieved by a method for operating a combination system, wherein the combination system has a heat pump circuit, wherein a refrigerant is evaporated in a refrigerant evaporator, wherein the evaporated refrigerant is fed to a compressor, wherein the temperature and pressure of the refrigerant are increased in the compressor, wherein the refrigerant is fed to a refrigerant condenser after the compressor, wherein the refrigerant condenses in the refrigerant condenser, wherein the refrigerant is fed to a throttle device, wherein the temperature and pressure of the refrigerant are reduced in the throttle device, wherein the refrigerant is fed to the refrigerant evaporator after the throttle device, wherein in a heat generation system, a cooling medium flows in a cooling circuit, wherein the cooling medium is heated in the heat generation system, wherein the cooling medium is fluidly fed to the refrigerant evaporator in such a way thatthat the refrigerant is heated and the cooling medium is cooled.,

[0015] Advantageous further developments are specified in the subclaims.

[0016] The invention therefore proposes the use of a refrigerant circuit, which can also be referred to as a left-handed Joule cycle, which can be used on the one hand as a refrigeration circuit for electrolysis and on the other hand as a high-temperature heat pump for oxygen heating and steam generation.

[0017] The basic working principle of the invention is as described below. After a refrigerant has absorbed the heat from the warm water leaving the electrolyzer, the refrigerant is evaporated while the water is cooled and fed back into the electrolyzer. It is then compressed to a higher pressure and temperature level in the compressor, which can also be referred to as a refrigerant compressor. The heat is then initially used to heat up the pressurised oxygen, which is produced as a by-product of electrolysis, while all the latent heat is used to generate low-pressure steam in the condenser, which can also be referred to as a refrigerant condenser. The hot and pressurised oxygen can then be expanded in an expansion turbine to generate electricity and then released into the air or transported and used for various purposes (e.g.steel production, oxyfuel combustion or oxygen enrichment of the sea) if the transport distance is appropriate for the corresponding quantity.

[0018] The low-pressure steam generated in the refrigerant condenser can be used to operate a direct air capture system, which requires large volumes of low-pressure steam to filter carbon dioxide (CO2) from the air. This configuration eliminates the need for external heating and cooling, as the direct air capture system can be precisely sized to match the electrolysis and heat pump.

[0019] The advantages of the system and method according to the invention are:

[0020] - Use of a refrigerant circuit to cool the electrolysis and simultaneously heat oxygen to generate electricity and steam for direct air capture. - Low-pressure steam generation in a remote area would meet the needs of direct air capture by utilizing heat from the heat pump.

[0021] - No external pumping of fresh water is required.

[0022] - Reliable cooling system for electrolysis in remote and hot areas.

[0023] - Use of oxygen, which is a by-product of electrolysis, to generate electricity.

[0024] - Generation of negative carbon dioxide (CO2) emissions through direct air capture.

[0025] - The already clean and climate-neutral production of green hydrogen will become even cleaner by providing not only a green fuel but also negative carbon dioxide (CO2) emissions.

[0026] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings.

[0027] Identical components or components with the same function are marked with the same reference symbols.

[0028] Examples of embodiments of the invention are described below with reference to the drawings. These are not intended to represent the examples to scale; rather, the drawing, which serves to explain the invention, is presented in a schematic and / or slightly distorted form. For supplements to the teachings immediately apparent in the drawings, reference is made to the relevant prior art. They show:

[0029] Figure 1 is a schematic representation of a combined system according to the invention

[0030] Figure 1 shows a combination system 1 according to the invention. The combination system 1 comprises a heat pump circuit, which is described below.

[0031] A refrigerant known from heat pumps is circulated in the combined system 1 in a circuit (counterclockwise in the figure). The circuit will now be described, beginning with a refrigerant evaporator 2. The refrigerant flows into the refrigerant evaporator 2 and is evaporated there. The thermal source required for this process comes from a heat generation system 3.

[0032] The heat generation plant 3 is an electrolyzer which is designed to produce hydrogen (H2) and oxygen (O2) from water by adding energy. The added energy can be based on renewable energy generation units, such as solar, wind or water. The produced hydrogen (H2) is discharged via a line 4. The added water is symbolically represented by line 5. The added energy is symbolically represented by line 6. The produced oxygen (O2) is symbolically represented by line 7.

[0033] The heat generation system 3 requires a cooling medium, in this case water, which is added to the heat generation system 3 via a line 8. Thus, cooled water is added to the heat generation system 3, heated there, and returned to the refrigerant evaporator 2 via another line 9.

[0034] In the refrigerant evaporator 2, the thermal energy of the heated water from the line 9 is used to evaporate the refrigerant. The water cools down and flows back via the line 8 to the heat generation system.

[0035] 3 . The refrigerant evaporator 2 can therefore also be referred to as cooling for the cooling medium in the electrolyzer 3 .

[0036] The refrigerant evaporator 2 is thus designed to evaporate the refrigerant. After the refrigerant evaporator 2, the refrigerant flows via a line 10 to a compressor 11. The compressor 11 is designed to compress the refrigerant, and the compressor 11 is fluidly connected to the refrigerant evaporator 2 via the line 10.

[0037] In the compressor 11, the temperature and pressure of the refrigerant are increased. The heated refrigerant flows via a line 12 through a pre-cooler 13. The oxygen (O2) generated in the heat generation system 3 also flows through the pre-cooler 13 through the line 7. The thermal energy of the refrigerant is transferred to the oxygen (O2) in the pre-cooler 13, whereby the temperature of the oxygen (O2) increases. The increased thermal energy of the oxygen (O2) is then converted into mechanical energy in an expander 14, wherein the mechanical energy can then be converted into electrical energy by means of a generator 15.

[0038] After flowing through the pre-cooler 13, the refrigerant is fed to a refrigerant condenser 16. The refrigerant condenses in the refrigerant condenser 16. The condensate required for condensation comes from a line 17. The line 17 is fluidically connected to a carbon dioxide system 18, wherein the carbon dioxide system 18 is designed to obtain carbon dioxide (CO2) 21 directly from the ambient air 19, wherein the vapor 20 that can be generated in the refrigerant condenser 16 is fluidically connected to the carbon dioxide system 18.

[0039] The combined system 1 further comprises a throttle device 22 designed to reduce the temperature and pressure of the refrigerant, wherein the throttle device is connected to the refrigerant condenser 16, wherein the refrigerant evaporator 2 is fluidly connected to the throttle device 22. The throttle device 22 can be a Joule-Thomson valve (JT valve) or an expansion turbine.

[0040] The heat pump circuit (symbolically represented by the frame 23) is closed again by returning the refrigerant to the refrigerant evaporator 2.

Claims

Patent claims 1. A combination system (1) comprising a heat pump circuit having a refrigerant evaporator (2) designed to evaporate a refrigerant, further comprising a compressor (11) designed to compress the refrigerant, wherein the compressor (11) is fluidically connected to the refrigerant evaporator (2), further comprising a refrigerant condenser (16) designed to condense the refrigerant, wherein the refrigerant condenser (16) is fluidically connected to the compressor (11), further comprising a throttle device (22) designed to reduce the temperature and pressure of the refrigerant, wherein the throttle device (22) is connected to the refrigerant condenser (16), wherein the refrigerant evaporator (2) is fluidically connected to the throttle device (22), further comprising a heat generation system (3) having a cooling circuit with a cooling medium,wherein the heat generation system (3) is designed such that the cooling medium can be heated during operation, characterized in that the cooling medium is fluidly connected to the refrigerant evaporator (2) in such a way that the refrigerant in the refrigerant evaporator (2) can be heated.

2. Combined system (1) according to claim 1, wherein the refrigerant evaporator (2) is designed such that the cooling medium can be cooled.

3. Combined system (1) according to claim 1 or 2, wherein the heat generating system (3) is designed as an electrolizer. Combined system (1) according to claim 3, wherein the cooling medium is water. Combined system (1) according to claim 3 or 4, with a pre-cooler (13) which is fluidly connected to an outlet of the compressor (11), wherein the oxygen generated in the electrolizer is supplied to the pre-cooler (13) such that the oxygen in the pre-cooler (13) can be heated. Combined system (1) according to claim 5, further comprising an expander (14) which is fluidly connected to the pre-cooler (13) and is designed such that the thermal energy of the oxygen heated in the pre-cooler (13) can be converted into mechanical energy. Combined system (1) according to claim 6, further comprising a generator (15) which is connected to the expander (14) in a torque-transmitting manner.Combined system (1) according to one of the preceding claims, wherein the refrigerant condenser (16) is fluidly connected to a condensate water line (17) such that water flowing in the condensate water line (17) can be converted into steam (20) in the refrigerant condenser (16). Combined system (1) according to claim 8, further comprising a carbon dioxide system (18), wherein the carbon dioxide system (18) is designed to extract carbon dioxide (CO2) directly from the ambient air, wherein the steam that can be generated in the refrigerant condenser (16) is fluidly connected to the carbon dioxide system (18). Method for operating a combination system (1), wherein the combination system (1) has a heat pump circuit, wherein a refrigerant is evaporated in a refrigerant evaporator (2), wherein the evaporated refrigerant is fed to a compressor (11), wherein the temperature and pressure of the refrigerant are increased in the compressor (11), wherein the refrigerant is fed to a refrigerant condenser (16) downstream of the compressor (11), wherein the refrigerant condenses in the refrigerant condenser (16), wherein the refrigerant is fed to a throttle device (22), wherein the temperature and pressure of the refrigerant are reduced in the throttle device (22), wherein the refrigerant is fed to the refrigerant evaporator (2) downstream of the throttle device (22), wherein in a heat generation system (3), a cooling medium flows in a cooling circuit, wherein the cooling medium is heated in the heat generation system (3), characterized inthat the cooling medium is fluidly supplied to the refrigerant evaporator (2) in such a way that the refrigerant is heated and the cooling medium is cooled. The method according to claim 10, wherein the heat generation system (3) is designed as an electrolizer and water is used as the cooling medium. The method according to claim 11, wherein a precooler (13) is arranged through which the refrigerant coming from the compressor (11) flows, wherein the oxygen generated in the electrolizer is supplied to the precooler (13) in such a way that the thermal energy of the refrigerant heats the oxygen coming from the electrolizer. Method according to claim 12, wherein the heated oxygen is fed to an expander (14) which converts the thermal energy of the oxygen into mechanical energy. Method according to one of the preceding claims, wherein the refrigerant condenser (16) is designed such that the thermal energy of the refrigerant is used to generate steam. Method according to claim 14, wherein the steam is fed to a carbon dioxide plant (21), wherein the carbon dioxide plant (21) is designed to extract carbon dioxide (CO2) directly from the ambient air, wherein the steam that can be generated in the refrigerant condenser (16) is fluidically connected to the carbon dioxide plant (18). Method according to claim 15, wherein water produced in the carbon dioxide plant (18) is fed to the refrigerant condenser (16), wherein the water is converted into steam in the refrigerant condenser (16).

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