Solid hydrogen storage system for green ammonia synthesis and control method thereof

Abstract

The invention belongs to the technical field of energy storage, and relates to a solid hydrogen storage system for green ammonia synthesis and a control method thereof. Comprising a solid hydrogen storage device which is provided with a hydrogen inlet, a hydrogen outlet, a heating medium inlet and a heating medium outlet; an outlet of the hydrogen purification device is connected with a hydrogen inlet of the solid hydrogen storage device through a hydrogen storage pipeline; an inlet of the green ammonia synthesis device is connected with a hydrogen outlet of the solid hydrogen storage device through a hydrogen release pipeline; an outlet of the green ammonia synthesis heat exchanger is connected with the heating device through a heating medium conveying pipeline; the heating device is connected with a heating medium inlet of the solid hydrogen storage device through a heating medium supply pipeline; and an inlet of the green ammonia synthesis heat exchanger is connected with a heating medium outlet of the solid hydrogen storage device through a heating medium return pipeline. Effective balance between green hydrogen supply fluctuation and continuous and stable operation of green ammonia synthesis is realized.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology and relates to a solid hydrogen storage system for green ammonia synthesis and its control method. Background Technology

[0002] Green ammonia, a low-carbon ammonia product produced based on renewable energy, uses green electricity from wind and solar power to electrolyze water to produce green hydrogen, which is then combined with nitrogen obtained from air separation to synthesize ammonia under the action of a catalyst. The entire process produces almost no carbon emissions. However, due to the significant intermittency and fluctuations of wind and solar power, the hydrogen production from water electrolysis is unstable, which in turn affects the stability requirements of hydrogen pressure and flow rate in the subsequent ammonia synthesis process. Traditional green ammonia systems often use high-pressure gaseous or low-temperature liquid hydrogen storage as a buffer, but this suffers from high energy consumption, poor safety, and low efficiency.

[0003] Current technologies have not effectively resolved the contradiction between fluctuating green hydrogen supply and continuous operation of green ammonia synthesis, particularly lacking an efficient mechanism for utilizing process waste heat. Conventional systems use independent heating sources for hydrogen release processes, resulting in energy waste and high operating costs. Furthermore, the lack of automated and precise control over hydrogen storage and release processes makes it difficult to adapt to the dynamic characteristics of renewable energy power generation, limiting the overall energy efficiency and intelligence level of green ammonia systems. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a solid-state hydrogen storage system for green ammonia synthesis and its control method, achieving an effective balance between fluctuations in green hydrogen supply and continuous and stable operation of green ammonia synthesis.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a solid-state hydrogen storage system for green ammonia synthesis, comprising: A solid-state hydrogen storage device, wherein the solid-state hydrogen storage device is provided with a hydrogen inlet, a hydrogen outlet, a heating medium inlet, and a heating medium outlet; A hydrogen purification device, wherein the outlet of the hydrogen purification device is connected to the hydrogen inlet of the solid hydrogen storage device via a hydrogen storage pipeline; A green ammonia synthesis unit, wherein the inlet of the green ammonia synthesis unit is connected to the hydrogen outlet of the solid hydrogen storage unit via a hydrogen release pipeline; A green ammonia synthesis heat exchanger is provided, wherein the outlet of the green ammonia synthesis heat exchanger is connected to a heating device via a heating medium delivery pipeline; the heating device is connected to the heating medium inlet of the solid hydrogen storage device via a heating medium supply pipeline; and the inlet of the green ammonia synthesis heat exchanger is connected to the heating medium outlet of the solid hydrogen storage device via a heating medium return pipeline.

[0006] Preferably, the hydrogen storage pipeline is equipped with a hydrogen storage flow sensor and a hydrogen storage control valve.

[0007] Preferably, the hydrogen release pipeline is equipped with a hydrogen release flow sensor and a hydrogen release control valve.

[0008] Preferably, the heating medium supply pipeline is equipped with a heating medium temperature sensor and a heating medium control valve.

[0009] Preferably, the solid hydrogen storage device is equipped with a temperature sensor and a pressure sensor for monitoring its internal state.

[0010] Preferably, it also includes a venting device, the inlet of which is connected to the solid hydrogen storage device via a hydrogen venting pipeline.

[0011] Preferably, the hydrogen release pipeline is equipped with a hydrogen release control valve.

[0012] Preferably, it also includes a controller; the hydrogen storage flow sensor, hydrogen storage control valve, hydrogen release flow sensor, hydrogen release control valve, heating medium temperature sensor, heating medium control valve, temperature sensor, pressure sensor and hydrogen release control valve are all connected to the controller.

[0013] Secondly, the present invention provides a control method for a solid hydrogen storage system for green ammonia synthesis, comprising the following steps: Hydrogen storage step: Green hydrogen from the hydrogen purification device is transported to the solid hydrogen storage device through the hydrogen storage pipeline for storage; Heating medium circulation steps: The heating medium flows sequentially through the green ammonia synthesis heat exchanger, the heating medium delivery pipeline, the heating device, and the heating medium supply pipeline into the solid hydrogen storage device, and then returns to the green ammonia synthesis heat exchanger through the heating medium return pipeline, forming a cycle; Hydrogen release step: The solid hydrogen storage device is heated by the heating medium flowing through it, causing the solid hydrogen storage device to release hydrogen gas. The released hydrogen gas is then transported to the green ammonia synthesis device through the hydrogen release pipeline.

[0014] Preferably, the heating medium circulation step further includes: when the temperature of the heating medium flowing through the heating device is lower than the set temperature, starting the heating device to supplement the heating medium with heating.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a solid-state hydrogen storage device as a buffer unit, effectively mitigating the volatility of green hydrogen supply from renewable energy sources and ensuring a continuous and stable hydrogen source for subsequent green ammonia synthesis units, thus solving a key bottleneck in the continuous production of green ammonia synthesis. Secondly, by using the waste heat generated during the green ammonia synthesis process through a heating medium circulation loop to provide the heat required for desorption in the solid-state hydrogen storage device, the invention achieves direct and high-value recovery and utilization of process waste heat within the system, significantly reducing the need for additional heating energy consumption, thereby achieving cascaded energy utilization and improved overall energy efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a solid hydrogen storage system for green ammonia synthesis according to the present invention.

[0018] The components include: 1. Solid-state hydrogen storage device; 2. Heating device; 3. Green ammonia synthesis heat exchanger; 4. Hydrogen purification device; 5. Green ammonia synthesis device; 6. Venting device; 7. Hydrogen storage pipeline; 8. Hydrogen release pipeline; 9. Heating medium return pipeline; 10. Heating medium delivery pipeline; 11. Heating medium supply pipeline; 12. Hydrogen release pipeline; 13. Hydrogen storage flow sensor; 14. Hydrogen storage control valve; 15. Temperature sensor; 16. Pressure sensor; 17. Hydrogen release flow sensor; 18. Hydrogen release control valve; 19. Heating medium temperature sensor; 20. Heating medium control valve; 21. Hydrogen release control valve. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings: The first objective of this invention is to provide a solid-state hydrogen storage system for green ammonia synthesis, such as... Figure 1 As shown, it includes: Solid hydrogen storage device 1, wherein the solid hydrogen storage device 1 is provided with a hydrogen inlet, a hydrogen outlet, a heating medium inlet and a heating medium outlet; Hydrogen purification device 4, the outlet of which is connected to the hydrogen inlet of solid hydrogen storage device 1 via hydrogen storage pipeline 7. The green ammonia synthesis unit 5 has its inlet connected to the hydrogen outlet of the solid hydrogen storage unit 1 via a hydrogen release pipeline 8. A green ammonia synthesis heat exchanger 3 is provided, the outlet of which is connected to a heating device 2 via a heating medium delivery pipeline 10; the heating device 2 is connected to the heating medium inlet of the solid hydrogen storage device 1 via a heating medium supply pipeline 11; and the inlet of the green ammonia synthesis heat exchanger 3 is connected to the heating medium outlet of the solid hydrogen storage device 1 via a heating medium return pipeline 9.

[0026] This invention incorporates a solid-state hydrogen storage device 1 as an intermediate buffer unit, capable of absorbing excess hydrogen during peak green hydrogen production and continuously releasing hydrogen during periods of low or interrupted production. This solves the problem of intermittent hydrogen supply caused by unstable power supply, ensuring the continuous and stable operation of the green ammonia synthesis unit 5. Simultaneously, by utilizing the waste heat from the green ammonia synthesis process to drive the hydrogen release process of the solid-state hydrogen storage material, it fully utilizes potentially wasted thermal energy, reducing the system's dependence on the external heating device 2 and improving overall energy efficiency. Furthermore, the design of the heating medium circulation path achieves coupling and matching of energy flows between processes, avoiding redundant construction and energy waste in traditional independent heating modes, resulting in significant energy-saving and consumption-reducing effects and engineering application value. This system is widely applicable to wind and solar power hydrogen production-green ammonia co-production projects and can also be extended to other chemical or energy scenarios requiring a stable hydrogen source.

[0027] The hydrogen storage pipeline 7 is equipped with a hydrogen storage flow sensor 13 and a hydrogen storage control valve 14. The hydrogen storage flow sensor 13 is used to monitor the instantaneous and cumulative flow of hydrogen through the hydrogen storage pipeline 7 in real time. Its measurement principle can employ common methods in the field, such as thermal mass flow measurement, differential pressure flow measurement, or ultrasonic flow measurement. The hydrogen storage control valve 14 is mainly used to regulate or cut off the hydrogen passage, realizing the start and stop control of hydrogen inlet operation. This valve can be a solenoid valve, an electric regulating valve, or a pneumatic shut-off valve, etc. The hydrogen release pipeline 8 is equipped with a hydrogen release flow sensor 17 and a hydrogen release control valve 18. The hydrogen release flow sensor 17 is used to monitor the instantaneous and cumulative flow of hydrogen through the hydrogen release pipeline 8 in real time, and can be a thermal mass flow meter, differential pressure flow meter, or Coriolis mass flow meter, etc. The hydrogen release control valve 18 is used to regulate the hydrogen on / off state and control the output rate, and can be an electrically operated regulating ball valve, a pneumatic diaphragm regulating valve, or an electromagnetic proportional valve, etc.

[0028] The heating medium supply pipeline 11 is equipped with a heating medium temperature sensor 19 and a heating medium control valve 20. The heating medium temperature sensor 19 is used to detect the actual temperature of the medium before it enters the hydrogen storage device, and can be a platinum resistance thermometer (Pt100 or Pt1000), a thermocouple (such as K-type or S-type), or other non-contact infrared temperature measuring devices. The heating medium control valve 20 is used to regulate the on / off state or flow rate of the heating medium flowing into the solid hydrogen storage device 1, and can be an electric regulating valve, a pneumatic diaphragm valve, or a solenoid valve, etc.

[0029] The solid-state hydrogen storage device 1 is equipped with a temperature sensor 15 and a pressure sensor 16 for monitoring its internal state. The temperature sensor 15 detects the temperature changes of the hydrogen storage alloy or metal hydride inside the solid-state hydrogen storage device 1 during hydrogen absorption and desorption. Its temperature sensing element can be a platinum resistance thermometer (Pt100), a thermocouple (such as K-type or T-type), or other high-precision temperature sensing elements. It is installed at the center of the hydrogen storage material filling area or near the side wall of the reactive zone to ensure that the collected data accurately reflects the temperature rise / fall dynamics of the core reaction area. The pressure sensor 16 continuously measures the pressure of the hydrogen space inside the solid-state hydrogen storage device 1. Its range can be selected according to the system design operating pressure, for example, covering a range from 0.1 MPa to 10 MPa. It has good resistance to hydrogen embrittlement and long-term stability. The installation interface is located at the top of the device or in the pressure stabilization section of the gas flow path to avoid the influence of local flow disturbances.

[0030] For example, the system of the present invention also includes a venting device 6, the inlet of which is connected to the solid hydrogen storage device 1 via a hydrogen venting pipeline 12. The venting device 6 enables excess hydrogen to be discharged and safely disposed of in a timely manner when the internal pressure of the system exceeds the safe range, solving the safety hazard problem that may be caused by the lack of reliable emergency pressure relief measures in existing systems, thereby achieving the technical effect of improving the overall system safety redundancy and preventing pressure accumulation from causing explosion accidents.

[0031] The hydrogen release pipeline 12 is equipped with a hydrogen release control valve 21. The hydrogen release control valve 21 can be a solenoid valve, an electric regulating valve, or a pneumatic shut-off valve, and can be an industrial-grade valve with fast response, good sealing performance, and explosion-proof certification. This valve has two basic operating states: under normal circumstances, it remains closed, blocking the flow of hydrogen to the release device 6; when the system detects that the internal pressure exceeds a preset safety threshold, the controller sends a signal to drive the valve to open rapidly, achieving active pressure relief.

[0032] For example, the system of the present invention also includes a controller; the hydrogen storage flow sensor 13, the hydrogen storage control valve 14, the hydrogen release flow sensor 17, the hydrogen release control valve 18, the heating medium temperature sensor 19, the heating medium control valve 20, the temperature sensor 15, the pressure sensor 16, and the hydrogen release control valve 21 are all connected to the controller.

[0033] The controller, as the intelligent hub of the entire system, receives real-time monitoring signals from various sensors and outputs adjustment commands to the corresponding control valves based on preset control strategies, thereby achieving closed-loop control of key processes such as hydrogen storage, hydrogen release, heating, and safe depressurization.

[0034] The controller can be an electronic device with data processing and I / O control functions, such as a programmable logic controller (PLC), industrial control computer, or embedded microcontroller. It is equipped with analog input modules for receiving current or voltage signals from various sensors, and digital output modules for driving solenoid valves or other switching actuators. The controller stores a control program that can trigger corresponding actions based on set threshold conditions. For example, when temperature sensor 15 detects that the internal temperature of the solid hydrogen storage device 1 is lower than the minimum temperature required for hydrogen release, the controller can automatically adjust the opening of the heating medium control valve 20 to increase the heat medium flow rate, or start the heating device 2 for auxiliary heating. When pressure sensor 16 detects that the internal pressure of the solid hydrogen storage device 1 exceeds a set pressure value, the controller will automatically increase the opening of the hydrogen release control valve 18 to accelerate hydrogen release and reduce the internal pressure of the device. When the hydrogen release flow sensor 17 detects that the hydrogen release amount of the solid hydrogen storage device 1 reaches a preset capacity value, the controller will automatically close the hydrogen release control valve 18 and the heating medium control valve 20, stopping the hydrogen release process. When the hydrogen storage flow sensor 13 detects that the hydrogen storage capacity of the solid hydrogen storage device 1 has reached its design capacity, the controller will automatically close the hydrogen storage control valve 14 to stop the hydrogen storage process. When the heating medium temperature sensor 19 detects that the temperature of the heating medium flowing through the heating medium supply pipeline 11 is lower than the set temperature value, the controller will automatically start the heating device 2 to ensure that the heating medium reaches the working temperature. When the pressure sensor 16 detects that the internal pressure of the solid hydrogen storage device 1 exceeds a higher safety set value, the controller will execute a safety interlock action: immediately open the hydrogen release control valve 21, and simultaneously close the hydrogen storage control valve 14, the hydrogen release control valve 18, and the heating medium control valve 20, releasing excess hydrogen to the release device 6 to ensure system safety.

[0035] A second objective of this invention is to provide a control method for a solid-state hydrogen storage system used in green ammonia synthesis, comprising the following steps: Hydrogen storage step: Green hydrogen from the hydrogen purification device 4 is transported to the solid hydrogen storage device 1 through the hydrogen storage pipeline 7 for storage; Heating medium circulation steps: The heating medium flows sequentially through the green ammonia synthesis heat exchanger 3, heating medium delivery pipeline 10, heating device 2, and heating medium supply pipeline 11 into the solid hydrogen storage device 1, and then returns to the green ammonia synthesis heat exchanger 3 through the heating medium return pipeline 9, forming a circulation; wherein, when the temperature of the heating medium flowing through the heating device 2 is lower than the set temperature, the heating device 2 is activated to supplement the heating medium with heating; Hydrogen release step: The solid hydrogen storage device 1 is heated by the heating medium flowing through it, causing the solid hydrogen storage device 1 to release hydrogen gas. The released hydrogen gas is then transported to the green ammonia synthesis device 5 through the hydrogen release pipeline 8.

[0036] The control method of this invention achieves intelligent management of hydrogen energy storage and release in a green ammonia synthesis system through the organic synergy of three core steps. In the hydrogen storage step, green hydrogen from the hydrogen purification unit 4 is safely stored in the solid-state hydrogen storage unit 1. This process effectively solves the intermittency and volatility problems of renewable energy hydrogen production, transforming the unstable green hydrogen supply into a stable and reliable hydrogen source reserve, providing a continuous raw material guarantee for subsequent ammonia synthesis. The innovation of the heating medium circulation step lies in the construction of a closed-loop system for energy cascade utilization. By recovering the reaction waste heat generated during green ammonia synthesis as the desorption heat source for the solid-state hydrogen storage material, it not only significantly reduces the system's dependence on external heating energy but also achieves efficient comprehensive utilization of process waste heat, greatly improving the energy utilization efficiency of the entire system. The introduction of an intelligent temperature control mechanism ensures that the desorption temperature is always maintained within the optimal operating range, guaranteeing the stability and reliability of the hydrogen release process. In the hydrogen release step, the heated solid-state hydrogen storage device 1 can release high-purity hydrogen on demand, providing a stable hydrogen source with pressure and flow rate for the downstream green ammonia synthesis unit 5. This on-demand supply mode not only meets the stringent requirements of the ammonia synthesis process for raw material stability but also avoids energy waste. The outstanding advantage of the entire control method lies in integrating energy storage buffering, waste heat utilization, and intelligent control into a comprehensive solution that balances energy supply and demand, optimizes process coupling, and ensures safe and reliable operation. It is particularly suitable for green ammonia production in scenarios with fluctuating renewable energy sources such as wind and solar power, providing important technical support for the industrialization of green ammonia.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solid-state hydrogen storage system for green ammonia synthesis, characterized in that, include: Solid hydrogen storage device (1), wherein the solid hydrogen storage device (1) is provided with a hydrogen inlet, a hydrogen outlet, a heating medium inlet and a heating medium outlet; Hydrogen purification device (4), the outlet of the hydrogen purification device (4) is connected to the hydrogen inlet of the solid hydrogen storage device (1) through a hydrogen storage pipeline (7); The green ammonia synthesis device (5) has its inlet connected to the hydrogen outlet of the solid hydrogen storage device (1) via a hydrogen release pipeline (8). A green ammonia synthesis heat exchanger (3) is provided, the outlet of which is connected to a heating device (2) via a heating medium delivery pipeline (10); the heating device (2) is connected to the heating medium inlet of the solid hydrogen storage device (1) via a heating medium supply pipeline (11); and the inlet of the green ammonia synthesis heat exchanger (3) is connected to the heating medium outlet of the solid hydrogen storage device (1) via a heating medium return pipeline (9).

2. The solid-state hydrogen storage system for green ammonia synthesis according to claim 1, characterized in that, The hydrogen storage pipeline (7) is equipped with a hydrogen storage flow sensor (13) and a hydrogen storage control valve (14).

3. The solid-state hydrogen storage system for green ammonia synthesis according to claim 2, characterized in that, The hydrogen release pipeline (8) is equipped with a hydrogen release flow sensor (17) and a hydrogen release control valve (18).

4. A solid-state hydrogen storage system for green ammonia synthesis according to claim 3, characterized in that, The heating medium supply pipeline (11) is equipped with a heating medium temperature sensor (19) and a heating medium control valve (20).

5. A solid-state hydrogen storage system for green ammonia synthesis according to claim 4, characterized in that, The solid hydrogen storage device (1) is equipped with a temperature sensor (15) and a pressure sensor (16) for monitoring its internal state.

6. A solid-state hydrogen storage system for green ammonia synthesis according to claim 5, characterized in that, It also includes a venting device (6), the inlet of which is connected to the solid hydrogen storage device (1) via a hydrogen venting pipeline (12).

7. A solid-state hydrogen storage system for green ammonia synthesis according to claim 6, characterized in that, The hydrogen venting pipeline (12) is equipped with a hydrogen venting control valve (21).

8. A solid-state hydrogen storage system for green ammonia synthesis according to claim 7, characterized in that, It also includes a controller; the hydrogen storage flow sensor (13), hydrogen storage control valve (14), hydrogen release flow sensor (17), hydrogen release control valve (18), heating medium temperature sensor (19), heating medium control valve (20), temperature sensor (15), pressure sensor (16) and hydrogen release control valve (21) are all connected to the controller.

9. A control method for a solid-state hydrogen storage system for green ammonia synthesis according to any one of claims 1 to 8, characterized in that, Includes the following steps: Hydrogen storage step: Green hydrogen from the hydrogen purification device (4) is transported to the solid hydrogen storage device (1) through the hydrogen storage pipeline (7) for storage; Heating medium circulation steps: The heating medium flows sequentially through the green ammonia synthesis heat exchanger (3), heating medium delivery pipeline (10), heating device (2), heating medium supply pipeline (11) into the solid hydrogen storage device (1), and then returns to the green ammonia synthesis heat exchanger (3) through the heating medium return pipeline (9) to form a cycle; Hydrogen release step: The solid hydrogen storage device (1) is heated by the heating medium flowing through it, so that the solid hydrogen storage device (1) releases hydrogen gas. The released hydrogen gas is transported to the green ammonia synthesis device (5) through the hydrogen release pipeline (8).

10. The control method for a solid-state hydrogen storage system for green ammonia synthesis according to claim 9, characterized in that, The heating medium circulation step further includes: when the temperature of the heating medium flowing through the heating device (2) is lower than the set temperature, the heating device (2) is activated to supplement the heating medium with heating.

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