Dual-mode electric heat storage heating and steam supply system based on closed desalinated water and operation method

Abstract

This invention provides a dual-mode electric thermal storage heating and steam supply system and its operation method based on closed-loop demineralized water. The boiler's built-in closed-loop demineralized water module is selectively connected to a secondary heat exchange module and an external steam generator. During the heating season, the boiler's built-in closed-loop demineralized water module is connected to the secondary heat exchange module. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes a primary heat exchange to form high-temperature demineralized water, it enters the secondary heat exchange module and exchanges heat with the return water of the heating network circulation module for residential heating. During the non-heating season, the boiler's built-in closed-loop demineralized water module is connected to the external steam generator. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes a primary heat exchange to form high-temperature demineralized water, it enters the external steam generator to produce industrial steam for industrial supply. This achieves dual-mode switching between residential heating during the heating season and industrial steam supply during the non-heating season, improving the unit's annual flexibility and peak-shaving capabilities, and adapting to the development trend of the new electricity spot market.

Description

Technical Field

[0001] This invention belongs to the field of solid-state electric thermal energy storage and thermal power peak-shaving steam supply technology, specifically relating to a dual-mode electric thermal energy storage heating and steam supply system based on closed-loop demineralized water and its operation method. Background Technology

[0002] Solid-state electric thermal storage hot water boilers are common external heating equipment in thermal power units. Their conventional thermal principle is as follows: electric heating elements heat the thermal storage material to a high temperature. After the circulating fan starts, low-temperature air is introduced into the thermal storage furnace. The air absorbs heat from the thermal storage material to form high-temperature hot air. This hot air undergoes a primary heat exchange with the boiler's built-in closed-loop demineralized water system via a wind-water heat exchanger. The heated demineralized water then undergoes a secondary heat exchange with the return water from the heating network, heating the network water for residential heating. However, currently, these solid-state electric thermal storage hot water boilers generally suffer from the prominent problem of seasonal idleness. They can only be put into operation during the heating season (approximately 4-5 months). During the non-heating season, core equipment such as the thermal storage material, closed-loop demineralized water system, and wind-water heat exchanger are completely idle. The annual utilization rate of the equipment is less than 50%, resulting in a long fixed asset investment payback period and serious resource waste.

[0003] To address the aforementioned issues, it is necessary to propose a well-designed and effective dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, along with its operation method. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water and its operation method.

[0005] One aspect of the present invention provides a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, including a thermal storage furnace and an external steam generator, wherein the thermal storage furnace includes an internal thermal storage body, an electric heating module, a circulating fan module, a wind-water heat exchanger, a boiler-built-in closed-loop demineralized water module, a secondary heat exchange module, and a heat network circulation module. The boiler's built-in closed-loop demineralized water module is selectively connected to the secondary heat exchange module and the external steam generator; wherein, During the heating season, the boiler's built-in closed-loop demineralized water module is connected to the secondary heat exchange module. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes the first heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the secondary heat exchange module and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating. During the non-heating season, the boiler's built-in closed-loop demineralized water module is connected to the external steam generator. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes one heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the external steam generator to produce industrial steam for industrial steam supply.

[0006] Optionally, the system may also include a controller; The boiler's built-in closed-loop demineralized water module is connected to the external steam generator via a demineralized water branch pipe, wherein the demineralized water branch pipe is equipped with a first electric shut-off valve. The boiler's built-in closed-loop demineralized water module is connected to the secondary heat exchange module via a demineralized water main pipeline, wherein the demineralized water main pipeline is equipped with a second electric shut-off valve. The controller is electrically connected to the first electric shut-off valve and the second electric shut-off valve respectively, and selectively controls the opening of the first electric shut-off valve and the second electric shut-off valve.

[0007] Optionally, a dual interlocking structure consisting of electrical hard interlocking and software interlocking is provided between the first electric shut-off valve and the second electric shut-off valve. The dual interlocking structure is configured to prevent the first electric shut-off valve and the second electric shut-off valve from being fully open at the same time.

[0008] Optionally, a flow regulating valve is also installed on the demineralized water branch line.

[0009] Optionally, the outlet of the external steam generator is connected to the first return water inlet of the boiler's built-in closed demineralized water module via a return pipeline.

[0010] Optionally, the system also includes a demineralized water replenishment device; The outlet of the demineralized water makeup device is connected to the makeup water inlet of the boiler's built-in closed demineralized water module.

[0011] Optionally, the return water outlet of the secondary heat exchange module is connected to the second return water inlet of the boiler's built-in closed demineralized water module.

[0012] Another aspect of the present invention provides an operation method for a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, employing the aforementioned dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, the operation method comprising: During the heating season, the electric heating module heats the heat storage body to a preset temperature. The circulating fan module introduces low-temperature air to generate high-temperature hot air. The hot air passes through the air-water heat exchanger and exchanges heat with the demineralized water in the boiler's built-in closed demineralized water module to form high-temperature demineralized water. The high-temperature demineralized water enters the secondary heat exchange module and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating. During the non-heating season, after the demineralized water in the boiler's built-in closed demineralized water module completes one heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the external steam generator to produce industrial steam for industrial steam supply.

[0013] Optionally, the running method further includes: During the non-heating season, demineralized water is replenished to the boiler's built-in closed demineralized water module through a demineralized water replenishment device.

[0014] Optionally, the running method further includes: The controller selectively controls the opening of the first and second electric shut-off valves to switch between heating mode and steam supply mode during the heating season and non-heating season.

[0015] This invention provides a dual-mode electric thermal storage heating and steam supply system and operation method based on closed-loop demineralized water. This system enables the same solid-state electric thermal storage system to provide heating during the heating season and steam during the non-heating season. It reuses the original thermal storage body, the boiler's built-in closed-loop demineralized water system, and other core equipment, improving the annual utilization rate of the equipment, completely solving the problem of equipment idleness during the non-heating season, and shortening the fixed asset investment payback period. It requires no damage to the original boiler's core structure, involves minimal modification work, has a short cycle, and is suitable for low-cost retrofitting of existing boilers. The built-in closed-loop demineralized water module can be selectively connected to the secondary heat exchange module and the external steam generator during the heating season. It can fully restore the original heating function, and during the non-heating season, it can stably produce steam through an external steam generator to fully meet the requirements of industrial steam supply and residential heating without affecting the stability of the original system operation; it can make full use of the waste heat of the original boiler's built-in closed demineralized water system, without the need for additional heating, thus reducing heat loss; it can fully retain the advantages of the original heat storage body in low-valley heat storage and peak-peak heat release, and can participate in peak shaving in both modes of the electricity spot market; during the non-heating season, it can replace the steam extraction of the steam turbine to supply steam, reduce steam extraction losses, release the unit's power generation capacity, improve the overall benefits of the power plant, and significantly enhance the unit's competitiveness and risk resistance in the new electricity spot market. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water according to an embodiment of the present invention. Figure 2 This is a schematic flowchart illustrating the operation method of a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, according to another embodiment of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1As shown, one aspect of the present invention provides a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, including a thermal storage furnace and an external steam generator 3. The thermal storage furnace includes an internal thermal storage body, an electric heating module, a circulating fan module, a wind-water heat exchanger, a boiler-built-in closed-loop demineralized water module 1, a secondary heat exchange module 2, and a heat network circulation module. In other words, this system is based on the original thermodynamic principle of a solid-state electric thermal storage hot water boiler, fully utilizing the original thermal storage body, wind-water heat exchanger, boiler-built-in closed-loop demineralized water system, and other core equipment. Each device maintains its original connection relationship and working principle, ensuring normal operation during the heating season. The system adds an external steam generator 3 to the existing equipment.

[0019] The boiler's built-in closed-loop demineralized water module 1 is selectively connected to the secondary heat exchange module 2 and the external steam generator 3; wherein, During the heating season, the boiler's built-in closed-loop demineralized water module 1 is connected to the secondary heat exchange module 2. The electric heating module heats the heat storage body to a preset temperature, and the circulating fan module introduces low-temperature air to generate high-temperature hot air. The hot air passes through the air-water heat exchanger and completes a primary heat exchange with the demineralized water in the boiler's built-in closed-loop demineralized water module 1 to form high-temperature demineralized water. The high-temperature demineralized water then enters the secondary heat exchange module 2 and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating.

[0020] During the non-heating season, the boiler's built-in closed-loop demineralized water module 1 is connected to the external steam generator 3. The electric heating module heats the heat storage body to a preset temperature, and the circulating fan module introduces low-temperature air to generate high-temperature hot air. The hot air exchanges heat with the demineralized water in the boiler's built-in closed-loop demineralized water module 1 through the air-water heat exchanger to form high-temperature demineralized water. The high-temperature demineralized water then enters the external steam generator 3 to generate industrial steam for industrial steam supply.

[0021] The dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water provided by this invention achieves seamless switching between two modes—restoring the original heating function during the heating season and directly extracting high-temperature demineralized water to generate steam during the non-heating season—by adding an external steam generator without damaging the core structure of the original solid-state electric thermal storage boiler. This maximizes the reuse of the original thermal storage body and closed-loop demineralized water system, reducing the cost and time required for modification. At the same time, it retains the peak-shaving advantages of storing heat during off-peak hours and releasing heat during peak hours, improving the unit's flexibility and peak-shaving capabilities throughout the year, better adapting to the trends of the electricity spot market, and enhancing the overall profitability of the power plant.

[0022] For example, such as Figure 1As shown, the system also includes a controller; the boiler-built closed demineralized water module 1 is connected to the external steam generator 3 through a demineralized water branch pipe 4, wherein the demineralized water branch pipe 4 is equipped with a first electric shut-off valve 5, which controls the opening and closing of the demineralized water branch pipe 4.

[0023] The boiler's built-in closed-loop demineralized water module 1 is connected to the secondary heat exchange module 2 via the demineralized water main pipeline 6. The demineralized water main pipeline 6 is equipped with a second electric shut-off valve 7, which controls the opening and closing of the demineralized water main pipeline 6.

[0024] The controller is electrically connected to the first electric shut-off valve 5 and the second electric shut-off valve 7 respectively, and selectively controls the opening of the first electric shut-off valve 5 and the second electric shut-off valve 7.

[0025] In this embodiment, the controller can be a DCS control system. The DCS control system selectively controls the opening of the first electric shut-off valve 5 and the second electric shut-off valve 7 to automatically switch between heating mode and non-heating mode.

[0026] In this embodiment, by setting a first electric shut-off valve, a second electric shut-off valve, and a controller, the automated and selective control of the demineralized water flow direction is realized, providing an execution-level foundation for seamless switching between dual modes. This allows the system to switch between heating mode and steam supply mode without manual intervention, improving the system's ease of operation and reliability.

[0027] For example, a double interlocking structure consisting of electrical hard interlocking and software interlocking is provided between the first electric shut-off valve 5 and the second electric shut-off valve 7. The double interlocking structure is configured to prevent the first electric shut-off valve 5 and the second electric shut-off valve 7 from being fully open at the same time.

[0028] Specifically, a dual interlocking protection unit is provided between the first electric shut-off valve 5 and the second electric shut-off valve 7. The dual interlocking protection unit includes an electrical hard interlocking circuit and a software logic interlocking module. The electrical hard interlocking circuit realizes the interlocking of the electrical control circuits of the first electric shut-off valve 5 and the second electric shut-off valve 7 through relay contact interlocking. The software logic interlocking module is integrated into the DCS control system and is used to prevent the first electric shut-off valve 5 and the second electric shut-off valve 7 from being in the fully open state at the logic level.

[0029] In this embodiment, by setting a double interlocking structure consisting of electrical hard interlocking and software interlocking between the first electric shut-off valve and the second electric shut-off valve, both valves are prohibited from being fully open at the same time. This effectively avoids problems such as demineralized water crossflow, pressure fluctuation, and flow disorder, ensuring the safety and stability of the system during mode switching and operation, and achieving truly seamless switching.

[0030] For example, such as Figure 1 As shown, a flow regulating valve 8 is also installed on the demineralized water branch pipe 4. The flow regulating valve 8 is used to regulate the flow rate of the demineralized water in the demineralized water branch pipe 4.

[0031] In this embodiment, by adding a flow regulating valve to the demineralized water branch pipeline, the flow rate and pressure of the demineralized water at the inlet of the external steam generator are precisely regulated, thereby improving the control accuracy of steam output and quality, ensuring that the temperature fluctuation of industrial steam supply during the non-heating season is ≤±5℃ and the pressure fluctuation is ≤±0.02MPa, meeting the strict requirements of industrial users for steam quality.

[0032] For example, such as Figure 1 As shown, the outlet of the external steam generator 3 is connected to the first return water inlet of the boiler built-in closed demineralized water module 1 through the return pipe 9, forming a demineralized water circulation loop. This allows the demineralized water after heat exchange to return to the system for reheating and reuse, avoiding water waste, improving the overall thermal efficiency of the system (≥94%), and achieving energy-saving operation.

[0033] For example, such as Figure 1 As shown, the system also includes a demineralized water replenishment device 10; the outlet of the demineralized water replenishment device 10 is connected to the water replenishment port of the boiler built-in closed demineralized water module 1.

[0034] In this embodiment, by adding a demineralized water replenishment device and connecting it to the water replenishment port of the closed demineralized water module, the liquid level loss can be automatically replenished when high-temperature demineralized water is drawn out for steam generation during the non-heating season, maintaining the normal liquid level and operating pressure of the closed demineralized water system, and ensuring continuous and stable operation under the steam supply mode during the non-heating season.

[0035] For example, such as Figure 1 As shown, the return water outlet of the secondary heat exchange module 2 is connected to the second return water inlet of the boiler-built closed demineralized water module 1, realizing the complete return circulation of demineralized water after secondary heat exchange during the heating season. This ensures that the system can operate stably for a long time in the heating mode without the need for additional water replenishment, thus reducing operating and maintenance costs.

[0036] like Figure 2As shown, another aspect of the present invention provides an operation method S100 for a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, employing the dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water described above. The specific structural features of this dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water have been described in detail above and will not be repeated here.

[0037] like Figure 2 As shown, the operation method S100 of the dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water includes: S110. During the heating season, the electric heating module heats the heat storage body to a preset temperature. The circulating fan module introduces low-temperature air to generate high-temperature hot air. The hot air passes through the air-water heat exchanger and exchanges heat with the demineralized water in the boiler's built-in closed demineralized water module to form high-temperature demineralized water. The high-temperature demineralized water enters the secondary heat exchange module and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating.

[0038] S120. During the non-heating season, after the demineralized water in the boiler's built-in closed demineralized water module completes one heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the external steam generator to produce industrial steam for industrial steam supply.

[0039] For example, the running method further includes: During the non-heating season, demineralized water is replenished to the boiler's built-in closed demineralized water module through a demineralized water replenishment device.

[0040] For example, the running method further includes: The controller selectively controls the opening of the first and second electric shut-off valves to switch between heating mode and steam supply mode during the heating season and non-heating season.

[0041] Specifically, such as Figure 1 As shown, the specific process of the operation method S100 of the dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water is as follows: 1) Heating season switching process: The controller issues a heating mode command, the first electric shut-off valve 5 is fully closed and locked, the second electric shut-off valve 7 is opened, the demineralized water branch pipe 4 is cut off, and the demineralized water main pipe 6 is opened; the system restores the original thermal flow, the electric heating module heats the heat storage body to about 650℃, the circulating fan introduces low-temperature air to generate high-temperature hot air, the hot air completes the first heat exchange with the demineralized water in the boiler built-in closed demineralized water module 1 through the air-water heat exchanger, the high-temperature demineralized water enters the secondary heat exchange module 2 to exchange heat with the heating network circulating water return water, heats the heating network water and supplies it for heating, realizing the original heating function.

[0042] 2) Non-heating season switching process: The controller issues a steam supply mode command, the second electric shut-off valve 7 is fully closed and locked, the first electric shut-off valve 5 is opened, and the demineralized water branch pipe 4 is connected; the demineralized water makeup device 10 is started simultaneously to maintain the stable liquid level in the boiler's built-in closed demineralized water module 1; the original heat storage and hot air heat exchange process remains unchanged, the high-temperature demineralized water enters the external steam generator 3 through the demineralized water branch pipe 4, and after releasing heat energy, it returns to the boiler's built-in closed demineralized water module 1 through the return pipe 9, and the external steam generator 3 produces qualified industrial steam for supply; the original heat storage and hot air heat exchange process does not need to be changed throughout the process, and there are no parameter fluctuations or manual intervention during the switching process.

[0043] The present invention relates to a dual-mode electric thermal storage heating and steam supply system and its operation method based on closed-loop demineralized water, which effectively solves the core pain points of existing solid-state electric thermal storage hot water boilers, fully utilizes the potential of existing equipment, and achieves both technological and economic improvements. The specific effects are as follows: 1) Significantly improved equipment utilization: The same solid electric thermal storage system can provide heating during the heating season and steam during the non-heating season. It reuses the original thermal storage body, boiler built-in closed demineralized water system and other core equipment. The annual equipment utilization rate has increased from less than 50% to more than 90%, completely solving the problem of equipment idleness during the non-heating season and shortening the fixed asset investment payback period.

[0044] 2) Low cost and short cycle for renovation: No need to damage the original core structure of the boiler, only add demineralized water branch pipes, external steam generators and demineralized water makeup devices. The amount of renovation work is small and the cycle can be controlled within 50 days, which is suitable for the low-cost renovation needs of existing boilers.

[0045] 3) Stable and reliable operation with strong compatibility: The first and second electric shut-off valves are equipped with a double interlocking structure consisting of electrical hard interlocking and software interlocking, which prohibits the two valves from being fully open at the same time, eliminating problems such as demineralized water crossflow and parameter fluctuations, and ensuring a smooth switching process; the original heating function can be fully restored during the heating season, and stable steam production is achieved during the non-heating season, with steam temperature fluctuations ≤ ±5℃ and pressure fluctuations ≤ ±0.02MPa, fully meeting the requirements of industrial steam supply and residential heating, without affecting the operational stability of the original system.

[0046] 4) Significant energy saving effect: It makes full use of the waste heat of the original closed demineralized water system, eliminating the need for additional heating and reducing heat loss; the demineralized water adopts a circulating reflux design, eliminating waste, and the overall thermal efficiency of the system is ≥94%, which is superior to conventional renovation schemes.

[0047] 5) Enhanced peak-shaving capacity and overall profitability: It fully retains the advantages of the original heat storage body in low-valley heat storage and high-peak heat release, and can participate in peak shaving in the electricity spot market in both modes; it replaces the steam turbine extraction for steam supply during the non-heating season, reduces steam extraction losses, releases the unit's power generation capacity, and is expected to increase the power plant's overall profitability by 8%-12% annually, significantly enhancing the unit's competitiveness and risk resistance in the new electricity spot market.

[0048] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, characterized in that, It includes a regenerator furnace and an external steam generator, wherein the regenerator furnace includes an internal regenerator, an electric heating module, a circulating fan module, a water-air heat exchanger, a boiler-built closed demineralized water module, a secondary heat exchange module, and a heat network circulation module; The boiler's built-in closed-loop demineralized water module is selectively connected to the secondary heat exchange module and the external steam generator; wherein, During the heating season, the boiler's built-in closed-loop demineralized water module is connected to the secondary heat exchange module. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes the first heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the secondary heat exchange module and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating. During the non-heating season, the boiler's built-in closed-loop demineralized water module is connected to the external steam generator. After the demineralized water in the boiler's built-in closed-loop demineralized water module completes one heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the external steam generator to produce industrial steam for industrial steam supply.

2. The system according to claim 1, characterized in that, The system also includes a controller; The boiler's built-in closed-loop demineralized water module is connected to the external steam generator via a demineralized water branch pipe, wherein the demineralized water branch pipe is equipped with a first electric shut-off valve. The boiler's built-in closed-loop demineralized water module is connected to the secondary heat exchange module via a demineralized water main pipeline, wherein the demineralized water main pipeline is equipped with a second electric shut-off valve. The controller is electrically connected to the first electric shut-off valve and the second electric shut-off valve respectively, and selectively controls the opening of the first electric shut-off valve and the second electric shut-off valve.

3. The system according to claim 2, characterized in that, The first electric shut-off valve and the second electric shut-off valve are provided with a double interlocking structure consisting of electrical hard interlocking and software interlocking. The double interlocking structure is configured to prevent the first electric shut-off valve and the second electric shut-off valve from being fully open at the same time.

4. The system according to claim 2, characterized in that, A flow regulating valve is also installed on the demineralized water branch pipeline.

5. The system according to claim 1, characterized in that, The outlet of the external steam generator is connected to the first return water inlet of the boiler's built-in closed demineralized water module via a return pipeline.

6. The system according to claim 1, characterized in that, The system also includes a demineralized water replenishment device; The outlet of the demineralized water makeup device is connected to the makeup water inlet of the boiler's built-in closed demineralized water module.

7. The system according to claim 1, characterized in that, The return water outlet of the secondary heat exchange module is connected to the second return water inlet of the boiler's built-in closed demineralized water module.

8. An operation method for a dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, characterized in that, The dual-mode electric thermal storage heating and steam supply system based on closed-loop demineralized water, as described in any one of claims 1 to 7, includes the following operating method: During the heating season, the electric heating module heats the heat storage body to a preset temperature. The circulating fan module introduces low-temperature air to generate high-temperature hot air. The hot air passes through the air-water heat exchanger and exchanges heat with the demineralized water in the boiler's built-in closed demineralized water module to form high-temperature demineralized water. The high-temperature demineralized water enters the secondary heat exchange module and exchanges heat with the heat network circulating water return water of the heat network circulation module for residential heating. During the non-heating season, after the demineralized water in the boiler's built-in closed demineralized water module completes one heat exchange to form high-temperature demineralized water, the high-temperature demineralized water enters the external steam generator to produce industrial steam for industrial steam supply.

9. The operating method according to claim 8, characterized in that, The operating method further includes: During the non-heating season, demineralized water is replenished to the boiler's built-in closed demineralized water module through a demineralized water replenishment device.

10. The operating method according to claim 8, characterized in that, The operating method further includes: The controller selectively controls the opening of the first and second electric shut-off valves to switch between heating mode and steam supply mode during the heating season and non-heating season.

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