A steam heating system based on gas-electricity storage multi-energy coupling and a control method thereof

Abstract

The application discloses a steam heat supply system based on gas-electricity storage multi-energy coupling and a control method. The heat supply system comprises an electric heat supply unit, a gas heat supply unit, a steam heat storage unit, a steam supply regulation unit and an intelligent control module. Through reasonable connection between units, design of control valves and control of the intelligent control module, the system can be flexibly switched according to energy prices and supply and demand conditions, and optimal operation of heat supply economy is realized. At the same time, the steam heat storage device stores excess heat to cope with power peak and extreme weather and other emergencies.

Description

Technical Field

[0001] This invention relates to the field of heating technology, specifically to a steam heating system and control method based on gas-electric-storage multi-energy coupling. Background Technology

[0002] Clean heating refers to a heating method that utilizes clean energy sources such as natural gas, electricity, geothermal energy, biomass energy, solar energy, industrial waste heat, and nuclear energy to provide safe, green, and economical heat to users, either directly or through efficient transmission and distribution networks. Electric heating technology, as an important component of clean heating technology, uses electricity as its energy source and employs heating equipment such as electric boilers, electric heat pumps, heating cables, electric heating films, and electric heaters to provide heat to buildings. Electric heating technology is flexible in its layout and operation and can be widely used in centralized and distributed heating scenarios in urban and rural areas.

[0003] Among various electric heating technologies, electrode boiler technology generates hot water or steam by passing high-voltage (above 6kV) current through electrodes directly onto boiler water with a certain conductivity. Compared with traditional electric heating tube boilers, it has higher thermal efficiency, lower cost, and smaller footprint, and has therefore been widely used in large-scale district heating systems in recent years. In engineering applications, electrode boilers are often integrated with water storage systems for heating. This not only allows for peak-shaving and heating by utilizing off-peak electricity, but also helps balance the volatility of renewable energy sources such as solar and wind power, promoting the large-scale consumption of renewable energy.

[0004] However, on the one hand, the installed capacity of new energy power in many regions is insufficient to meet heating demand (especially steam heating demand), which means that the actual system operation still requires the use of electricity generated by thermal power plants for heating, and the goal of clean heating cannot be fundamentally achieved; on the other hand, at present, the cost of energy or peak electricity during the peak period for electric heating using new energy power is higher than that of coal-fired heating methods, which is unacceptable to heat users in areas where relevant subsidies are not implemented, thus limiting the large-scale development of clean electric heating technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide a steam heating system and control method based on gas-electricity-storage coupling. The system can flexibly switch according to the real-time price and supply and demand of various energy sources to achieve optimal heating economic operation.

[0006] To achieve the above objectives, this invention designs a steam heating system based on gas-electric-storage multi-energy coupling, wherein the heating system includes an electric heating unit, a gas heating unit, a steam storage unit, and a steam supply control unit. The steam storage unit includes at least a steam accumulator, which generates steam for external supply by controlling the pressure and water level of the steam accumulator and flash evaporation under reduced pressure. The steam supply control unit includes at least a steam distribution cylinder, which is used to collect the main steam from each unit and supply steam to heat users. The electric heating unit includes at least an electrode boiler, a first deaerator, and a first water pump; the inlet pipe is connected to the first deaerator, and the outlet pipe of the first deaerator is connected to the inlet of the electrode boiler and the steam accumulator via the first water pump; the outlet pipe of the electrode boiler is connected to the steam distribution cylinder and the steam inlet of the steam accumulator via an eighth control valve. The electrode boiler includes an electrode assembly, an inner cylinder, an outer cylinder, and an actuator. A second water pump is provided with its two ends connected to the outer cylinder outlet and the inner cylinder inlet of the electrode boiler, respectively, to input deoxygenated water in the outer cylinder into the inner cylinder via the second water pump. The gas-fired heating unit includes at least a gas-fired boiler, a second deaerator, and a fourth water pump; the inlet pipe is connected to the second deaerator, the outlet pipe of the second deaerator is connected to the inlet of the gas-fired boiler via the fourth water pump, and the outlet of the gas-fired boiler is connected to the steam inlet of the steam distribution cylinder via a fifth control valve. The steam outlet of the steam distribution cylinder is connected to the inlet of the first deaerator and the second deaerator respectively to provide a deaeration heat source; the output of the steam accumulator is connected to the inlet of the steam distribution cylinder via the sixth control valve.

[0007] Furthermore, the steam supply control unit also includes at least an intelligent control module, a fifth control valve, a sixth control valve, and an eighth control valve, wherein the intelligent control module is electrically connected to the control valves and the water pump.

[0008] Furthermore, a second control valve and a third control valve are respectively installed on the inlet pipes of the electrode boiler and the steam accumulator; a seventh control valve is installed on the side of the connection pipe between the eighth control valve and the steam accumulator near the steam accumulator; one outlet of the steam distribution cylinder is connected to the first deaerator via the first control valve, and the other outlet of the steam distribution cylinder is connected to the second deaerator via the fourth control valve, thereby providing a deaeration heat source for the deaerator.

[0009] Furthermore, a soft water system is installed on the inlet pipe, and the water is connected to the second deaerator after passing through the third water pump, and then to the first deaerator after passing through the water treatment device.

[0010] Furthermore, the flow rate ratio of the second water pump to the first water pump is 1:1 to 1:1.7.

[0011] Furthermore, the volumetric filling ratio of deoxygenated water in the steam accumulator is 20-90%.

[0012] Furthermore, the heat storage steam pressure in the steam accumulator is 2-4 MPa, and the heat release steam pressure is 0.6-2 MPa, wherein the heat release steam pressure does not exceed 50% of the heat storage steam pressure.

[0013] Furthermore, one output of the gas boiler is connected to the steam accumulator via the ninth control valve.

[0014] On the other hand, a steam heating control method based on gas-electricity-storage multi-energy coupling is proposed. The control method achieves multi-energy coupling by linking gas boilers, electrode boilers and steam accumulators. When gas prices, off-peak electricity prices and peak electricity prices fluctuate, a suitable steam supply route is selected to reduce operating costs for heat users. Let the off-peak electricity price be d1 yuan / kWh, the peak electricity price be d2 yuan / kWh (d2 > d1), and the price of 1 cubic meter of natural gas be r yuan / kWh, and its calorific value be equal to the electricity consumption of n kWh. When r / n < d1, a gas-fired boiler is used for heating; When r / n > d2, a coupled heating system of electrode boiler and steam accumulator is used. When d1≤r / n≤d2, a coupled heating system of gas boiler, electrode boiler and steam accumulator is adopted. During off-peak hours, a coupled heating mode of electrode boiler heating and steam accumulator heat storage is adopted; during peak hours, a combined heating mode of gas boiler and steam accumulator is adopted. Generally, steam accumulator heat supply is given priority. When the heat of steam accumulator is insufficient, gas boiler heat supply is adopted.

[0015] Furthermore, the control method includes a heat storage mode, a steam accumulator-only heat release mode (also known as a heat storage tank-only heat release mode), and a steam accumulator / electrode boiler / gas boiler switching mode.

[0016] Furthermore, the heat storage mode includes: A1. When the heat storage conditions are met, the heat storage mode is activated; A2. During the heat storage period (if there is no external steam demand during off-peak hours, the electrode boiler will start to produce steam and store it in the spherical tank for heat storage), when the pressure of the steam accumulator reaches or exceeds the first set value, the high-pressure electrode boiler will stop. After the boiler stops, the seventh control valve 19 will be closed. If the pressure of the steam accumulator drops to the second set value, the electrode boiler will automatically start heating, and the second set value is less than the first set value. A3. During the heat storage and supply period (such as the stage of simultaneous heat storage and supply by the electrode boiler during off-peak electricity hours: the electrode boiler starts to produce steam, part of which is stored in the spherical tank for heat storage, and the other part is supplied to the outside), when the pressure of the steam accumulator reaches or exceeds the first set value, the high-pressure electrode boiler is shut down, the eighth control valve 20 and the seventh control valve 19 are closed, the sixth control valve 18 is opened, the energy storage system supplies steam to the outside, and the deaerator remains open. If the pressure drops below the second set value, the high-pressure electrode boiler will automatically start heating, open the eighth control valve 20 and the seventh control valve 19, and close the sixth control valve 18. The steam accumulator's independent heat release mode includes: B1. When the conditions for independent heat release by the steam accumulator are met (such as during peak power periods, the independent heating stage of the steam accumulator: the electrode boiler is shut down, and the heat stored in the spherical tank is used for flash steam supply to the outside), the energy storage system supplies steam to the outside alone, the electrode boiler is in the off state, the eighth control valve 20 and the seventh control valve 19 are closed, the sixth control valve 18 is opened, and the deaerator is shut down; until the pressure of the accumulator tank reaches the third set value, the steam accumulator / electrode boiler / gas boiler switching mode is started, and the third set value is less than the second set value. B2. The opening of the sixth control valve 18 is automatically adjusted according to the third set value of the steam accumulator pressure (default 0.7Mpa) and the steam distribution cylinder pressure to ensure that the steam distribution cylinder pressure meets the requirements. The switching modes for steam accumulator / electrode boiler / gas boiler include: C1. Switching between steam accumulator and electrode boiler / gas boiler in heat release mode: When the steam accumulator pressure is less than or equal to the third set value, the electrode boiler or gas boiler is turned on (which one is turned on is determined according to the gas supply route), the corresponding eighth control valve 20 or fifth control valve 17 is opened, and the sixth control valve 18 is kept open. One of the electrode boiler or gas boiler and the steam accumulator jointly supply heat to the outside, and the corresponding deaerator is started at the same time.

[0017] C2. When the steam accumulator pressure drops to the fourth set value, the energy storage system stops supplying steam to the outside, closes the sixth control valve 18, and the electrode boiler or gas boiler supplies steam to the outside separately, while the corresponding deaerator continues to operate; the fourth set value is less than the third set value.

[0018] C3. Keep the electrode boiler or gas boiler running until the steam demand deadline is reached, then stop or switch modes according to the new mode settings.

[0019] Based on cost optimization considerations or other user-specific needs, if switching between electrode boilers and gas boilers is required, the general approach is to gradually reduce the output of one while gradually increasing the output of the other, with the rate of increase in output pressure of the increasing output being slightly greater than the rate of decrease in pressure of the decreasing output.

[0020] Furthermore, the control method may also include a steam accumulator standby mode, which enables the steam accumulator to provide emergency heating. In this mode, a fifth and a sixth setpoint for the steam accumulator pressure are set, with the first setpoint > the second setpoint > the fifth setpoint > the sixth setpoint > the third setpoint > the fourth setpoint. When the steam accumulator pressure drops to the fifth setpoint, the electrode boiler or the gas boiler is activated, and one of the electrode boilers or the gas boiler works in conjunction with the steam accumulator to provide external heating, while the corresponding deaerator is activated simultaneously. When the steam accumulator pressure drops to the sixth setpoint, the energy storage system stops supplying steam to the outside.

[0021] The advantages and beneficial effects of this invention are as follows: This invention couples a gas-fired boiler, an electrode boiler, and a steam thermal storage device, replacing the simple gas-fired heating, electric heating, and electric-water thermal storage heating systems in some areas. It allows for flexible switching based on energy prices and supply and demand, achieving optimal economic operation of the heating system. Simultaneously, the steam thermal storage device stores excess heat to cope with peak electricity demand and emergencies such as extreme weather. Furthermore, this system can be combined with renewable energy sources such as solar and wind power to further improve the efficiency of new energy utilization and reduce environmental pollution. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the connection principle of the steam heating system of the gas-electric-storage multi-energy coupling of the present invention.

[0023] Marked in the image: 1. Intelligent control module; 2. Electrode boiler; 3. First control valve; 4. First deaerator; 5. Second control valve; 6. First water pump; 7. Second water pump; 8. Third control valve; 9. Gas boiler; 10. Water treatment device; 11. Soft water system; 12. Third water pump; 13. Fourth water pump; 14. Second deaerator; 15. Fourth control valve; 16. Steam accumulator; 17. Fifth control valve; 18. Sixth control valve; 19. Seventh control valve; 20. Eighth control valve; 21. Steam distributor cylinder. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0025] Example 1: like Figure 1 As shown, a steam heating system based on gas-electric-storage multi-energy coupling is characterized in that the heating system includes an electric heating unit, a gas heating unit, a steam storage unit, and a steam supply control unit. The steam storage unit includes at least a steam accumulator 16, which generates steam for external supply by controlling the pressure and water level of the steam accumulator and flash evaporation under reduced pressure. The steam supply control unit includes at least a steam distribution cylinder 21, which is used to collect the main steam of each unit and supply steam to the heat users. The electric heating unit includes at least an electrode boiler 2, a first deaerator 4, and a first water pump 6; the inlet pipe is connected to the first deaerator 4, and the outlet pipe of the first deaerator 4 is connected to the inlet of the electrode boiler 2 and the steam accumulator 16 via the first water pump 6; the outlet pipe of the electrode boiler 2 is connected to the steam distribution cylinder 21 and the steam inlet of the steam accumulator 16 via the eighth control valve 20. The electrode boiler 2 includes an electrode assembly, an inner cylinder, an outer cylinder, and an actuator. A second water pump 7 is provided with its two ends connected to the outer cylinder outlet and the inner cylinder inlet of the electrode boiler, respectively, to input deoxygenated water in the outer cylinder into the inner cylinder via the second water pump 7. The gas heating unit includes at least a gas boiler 9, a second deaerator 14 and a fourth water pump 13; the inlet pipe is connected to the second deaerator 14, the outlet pipe of the second deaerator 14 is connected to the inlet of the gas boiler 9 via the fourth water pump 13, and the outlet of the gas boiler 9 is connected to the steam inlet of the steam distribution cylinder 21 via the fifth control valve 17. The steam distribution cylinder can be provided with multiple outlets and inlets. The steam outlet of the steam distribution cylinder 21 is connected to the inlet of the first deaerator 4 and the second deaerator 14 respectively to provide a deaeration heat source; the output of the steam accumulator (16) is connected to the inlet of the steam distribution cylinder 21 via the sixth control valve 18, and at least one outlet of the steam distribution cylinder 21 is connected to the user's gas supply pipeline.

[0026] Regarding the electric heating unit, the water source is softened by the water softening system 11 and desalinated by the water treatment device 10 before entering the first deaerator 4 to become deoxygenated water, and then further enters the outer cylinder of the electrode boiler 2 through the first water pump 6; the deoxygenated water in the outer cylinder is input to the inner cylinder through the second water pump 7. The electrode assembly is immersed in the boiler water in the inner cylinder. By transmitting current into the boiler water, steam is generated and enters the steam distribution cylinder 21 via the eighth control valve 20. The steam output branch of the steam distribution cylinder 21 returns to the first deaerator 4 via the first control valve 3 to provide a deaeration heat source. The actuator is connected to the inner cylinder and the outer cylinder and can regulate the return flow of boiler water in the inner cylinder to the outer cylinder to control the liquid level in the inner cylinder.

[0027] Regarding the gas-fired heating unit, the water source flows into the soft water system 11 via the third water pump 12 for softening, and then enters the second deaerator 14 to become deoxygenated water. It then enters the gas-fired boiler 9 via the fourth water pump 13 to generate steam. The steam enters the steam distribution cylinder 21 via the fifth control valve 17. The steam output branch of the steam distribution cylinder 21 returns to the second deaerator 14 via the fourth control valve 15 to provide a deoxygenated heat source.

[0028] Regarding the steam heat storage unit, after passing through the third control valve 8 and the first water pump 6, deoxygenated water can be introduced into the steam heat storage unit 16 for filling or replenishing water; through the seventh control valve 19 and the eighth control valve 20, steam generated by the electrode boiler 2 can be introduced into the steam heat storage unit 16 below the deoxygenated water level, and the deoxygenated water can be heated by steam to achieve the heat storage process.

[0029] Preferably, the steam supply control unit further includes at least an intelligent control module 1, a fifth control valve 17, a sixth control valve 18, and an eighth control valve 20. The intelligent control module is electrically connected to the control valves and water pumps. Generally, all control valves and pumps included in the intelligent control design should be electrically connected to the control module (it is possible that some control valves only require manual control; this is generally a redundancy measure added for the safety and maintenance convenience of the entire system. Normal electrical control can realize the on / off control function of all pipelines). Including the control valves and pumps mentioned later, it can control the independent or combined operation of the electric heating unit, the gas heating unit, and the steam heat storage unit, and realize intelligent control of gas-electric-storage switching through the fifth control valve 17, the sixth control valve 18, and the eighth control valve 20.

[0030] Preferably, a second control valve 5 and a third control valve 8 are respectively installed on the water inlet pipes of the electrode boiler 2 and the steam accumulator 16 to control the water inlet of the electrode boiler 2 and the steam accumulator 16 respectively. In this embodiment, the output pipes of the electrode boiler 2 and the steam accumulator 16 are connected at the inlet of the steam distribution cylinder 21 and share a common input port. A seventh control valve 19 is installed on the side of the connection pipe between the eighth control valve 20 and the steam accumulator 16 near the steam accumulator 16 to control the steam generated by the electrode boiler 2 to enter the steam accumulator 16. One outlet of the steam distribution cylinder 21 is connected to the first deaerator 4 via the first control valve 3, and the other outlet of the steam distribution cylinder 21 (or a multi-branch connection) is connected to the second deaerator 14 via the fourth control valve 15 to provide a deaeration heat source for the deaerator.

[0031] Preferably, a soft water system 11 is installed on the water inlet pipe, and after passing through a third water pump 12, it is connected to a second deaerator 14, and after passing through a water treatment device 10, it is connected to a first deaerator 4, providing high-quality water sources for the gas boiler 9 and the electrode boiler 2 respectively.

[0032] According to the above design scheme, in addition to the steam accumulator 16, the third control valve 8 and the seventh control valve 19 are generally classified as steam heat storage units; the electric heating unit also includes the first control valve 3, the second control valve 5 and the water treatment device 10; the gas heating unit also includes the soft water system 11, the third water pump 12 and the fourth control valve 15.

[0033] Preferably, the flow rate ratio of the second water pump 7 to the first water pump 6 is 1:1 to 1:1.7. This is mainly because as steam is generated from the boiler water in the inner cylinder and enters the steam accumulator or steam distributor via the eighth control valve, the liquid level in the inner cylinder decreases, requiring the outer cylinder to replenish water to the inner cylinder via the second water pump. Simultaneously, the water in the outer cylinder needs to be replenished by deoxygenated water via the first water pump. Therefore, the flow rate ratio of the second water pump to the first water pump, along with the liquid levels in the outer and inner cylinders, needs to be adjusted reasonably according to the user's heating load. When the flow rate is lower than 1:1 (e.g., 1:0.9), the evaporation rate in the inner cylinder is low, resulting in a low heating load or low steam output temperature; conversely, when the flow rate is higher than 1:1.7, the ratio is reversed.

[0034] Preferably, the deoxygenated water volume filling ratio in the steam accumulator 16 is 20% to 90%. This is mainly because the steam distribution pipes in the steam accumulator account for about 15% to 20% of the total volume, and the minimum water volume in the steam accumulator should not be less than 20%. Otherwise, the introduced steam will not easily dissolve in the water, resulting in a mismatch between the pressure inside the steam accumulator and the high-temperature and high-pressure hot water level parameters, thus reducing the actual heat storage capacity. In addition, the steam vapor phase space inside the steam accumulator should not be less than 10%, so the deoxygenated water filling ratio should not exceed 90% to ensure stable steam output. Therefore, a deoxygenated water filling ratio of 20% to 90% is preferable.

[0035] Preferably, the heat storage steam pressure in the steam accumulator 16 is 2–4 MPa, and the heat release steam pressure is 0.6–2 MPa. This is mainly because the heat release process of the steam accumulator is achieved through depressurized flash evaporation within the spherical tank, thus the heat release steam pressure is lower than the heat storage steam pressure. Furthermore, considering the economic efficiency of heat storage, the heat release steam pressure should generally not exceed 50% of the heat storage steam pressure. In addition, when the heat storage steam pressure exceeds 4 MPa, the excessively thick spherical tank wall leads to problems with large-capacity (1000 m³) accumulators. 3 (The above) Spherical tanks are difficult and costly to manufacture, so it is not recommended to exceed 4MPa.

[0036] In this embodiment, the flow rate ratio of the second water pump 7 to the first water pump 6 is 1:1, the deoxygenated water volume filling ratio in the steam accumulator 16 is 20%, the heat storage steam pressure is 2MPa, and the heat release steam pressure is 0.6MPa.

[0037] Example 2: The difference from Example 1 is that in this example, the flow rate ratio of the second water pump 7 to the first water pump 6 is 1:1.7, the deoxygenated water volume filling ratio in the steam accumulator 16 is 90%, the heat storage steam pressure is 4MPa, and the heat release steam pressure is 2MPa.

[0038] Example 3: The difference from Embodiment 1 is that, in this embodiment, one output of the gas boiler 9 is connected to the steam accumulator 16 via the ninth control valve (the ninth control valve and its connection are not shown in the figure). This design is used for the gas boiler 9 to provide steam heat storage to the steam accumulator 16 so that the steam accumulator can maintain a certain heating capacity when both electric heating and gas heating are abnormal, thus ensuring continuous emergency heating of the system.

[0039] Example 4: The difference from Example 1 is that this example combines the two deaerators into one. For instance, only the first deaerator is retained, and a water pump is added to the inlet of the first deaerator. A pipeline connecting the first water pump 6 to the gas-fired boiler is added to the output end of the pump, and a control valve (not shown in the figure) is installed on this pipeline. Therefore, the configuration of the second deaerator 14 can be eliminated, or it can be retained as another input to the gas-fired boiler or as a backup. It should be noted that the first deaerator is generally irreplaceable and must be retained because the water quality requirements of the two deaerators are different. The deoxygenated water from the first deaerator can be used in the gas-fired boiler, while the deoxygenated water from the second deaerator cannot be used in the electrode boiler.

[0040] Example 5: A steam heating control method based on gas-electricity-storage multi-energy coupling can be based on any of the above-mentioned steam heating systems based on gas-electricity-storage multi-energy coupling and their preferred schemes. The control method achieves multi-energy coupling by linking a gas boiler, an electrode boiler and a steam accumulator. When gas prices, off-peak electricity prices and peak electricity prices fluctuate, a suitable steam supply route is selected to reduce operating costs for heat users. Let the off-peak electricity price be d1 yuan / kWh, the peak electricity price be d2 yuan / kWh (d2 > d1), and the price of 1 cubic meter of natural gas be r yuan / kWh, and its calorific value be equal to the electricity consumption of n kWh. When r / n < d1, a gas-fired boiler is used for heating; the intelligent control module controls the opening of the third water pump 12, the fourth water pump 13, the fourth control valve 15 and the fifth control valve 17, and closes the first water pump 6, the second water pump 7, the first control valve 3, the second control valve 5, the third control valve 8, the sixth control valve 18, the seventh control valve 19 and the eighth control valve 20, and adjusts the parameters of the gas-fired boiler (such as gas flow rate and flame size) to supply steam to the outside. When r / n > d2, coupled heating is provided by an electrode boiler and a steam accumulator. The intelligent control module first shuts down the gas-fired heating unit, specifically by controlling the shutdown of gas boiler 9, third water pump 12, fourth water pump 13, fourth control valve 15, and fifth control valve 17. Then, during off-peak electricity hours, the electric heating unit supplies steam, and the steam accumulator operates in heat storage mode, specifically by activating electrode boiler 2, steam accumulator 16, first water pump 6, second water pump 7, first control valve 3, second control valve 5, third control valve 8, seventh control valve 19, and eighth control valve 20, while shutting down the sixth control valve. Control valve 18 controls the electrode boiler to generate steam to the steam distribution cylinder and supply steam to the outside. At the same time, the electrode boiler stores the heat required for steam supply during peak power periods in the steam accumulator 16 through the seventh control valve 19. Finally, during peak power periods, the electric heating unit is turned off and the steam accumulator heating mode is turned on. That is, the sixth control valve 18 is turned on and the first water pump 6, the second water pump 7, the first control valve 3, the second control valve 5, the third control valve 8, the seventh control valve 19, and the eighth control valve 20 are turned off. By controlling the pressure and water level of the steam accumulator, steam is generated by pressure reduction flash evaporation and supplied to the outside. When there is surplus new energy (renewable energy) that needs to be consumed, the system can directly use the coupling of electrode boiler and steam accumulator for heating.

[0041] When d1≤r / n≤d2, a coupled heating system of gas boiler, electrode boiler and steam accumulator is adopted. During off-peak hours, a coupled heating mode of electrode boiler heating and steam accumulator heat storage is adopted; during peak hours, a combined heating mode of gas boiler and steam accumulator is adopted. Generally, steam accumulator heat supply is given priority. When the heat of steam accumulator is insufficient, gas boiler heat supply is adopted.

[0042] During off-peak electricity hours, the gas-fired heating unit is shut down, while the electric heating unit and steam storage unit are activated. Specifically, the intelligent control module shuts down the gas boiler 9, the third water pump 12, the fourth water pump 13, the fourth control valve 15, the fifth control valve 17, and the sixth control valve 18, and activates the electrode boiler 2, the steam accumulator 16, the first water pump 6, the second water pump 7, the first control valve 3, the second control valve 5, the third control valve 8, the seventh control valve 19, and the eighth control valve 20. The electrode boiler generates steam and supplies it to the steam distribution cylinder 21. Simultaneously, the electrode boiler stores the heat from a portion of the steam supplied during peak electricity hours in the steam accumulator 16 through the seventh control valve 19.

[0043] During peak electricity hours, the electric heating unit is shut down, and the combined heating mode of the gas boiler 9 and the steam storage unit is activated. This involves activating the gas boiler 9, the third water pump 12, the fourth water pump 13, the fourth control valve 15, the fifth control valve 17, and the sixth control valve 18, while shutting down the first water pump 6, the second water pump 7, the first control valve 3, the second control valve 5, the third control valve 8, the seventh control valve 19, and the eighth control valve 20. By controlling the steam accumulator pressure, the water level, and the gas boiler parameters, combined steam supply to the outside can be achieved. Alternatively, the steam accumulator 16 can be prioritized for heating, i.e., only the sixth control valve 18 is activated. If the heat storage supply is insufficient or reaches the set threshold, the gas boiler 9 is used for heating, i.e., only the gas boiler 9, the third water pump 12, the fourth water pump 13, the fourth control valve 15, and the fifth control valve 17 are activated.

[0044] Preferably, the control method includes a heat storage mode, a steam accumulator-only heat release mode (also known as a heat storage tank-only heat release mode), and a steam accumulator / electrode boiler / gas boiler switching mode.

[0045] Preferably, the heat storage mode includes: A1. When the heat storage conditions are met, start the heat storage mode. For example, after entering the off-peak electricity period, set 0:00 to start the high-pressure electrode boiler heat storage, start the first deaerator 4, open the eighth control valve 20, and when the electrode boiler pressure is ≥ the steam accumulator (heat storage tank) pressure, open the seventh control valve 19 and close the sixth control valve 18. A2. During the heat storage period (if there is no external steam demand during off-peak hours, the electrode boiler will start to produce steam and store it in the spherical tank for heat storage), when the pressure of the steam accumulator reaches or exceeds the first set value (2.5MPa in this embodiment), the high-pressure electrode boiler will stop. After the boiler stops, the seventh control valve 19 will be closed. If the steam accumulator pressure drops to the second set value, and the second set value is less than the first set value (the second set value in this embodiment is 2.4 MPa), the electrode boiler automatically starts heating, opens the eighth control valve 20 and the seventh control valve 19, and closes the sixth control valve 18; during this period, the deaerator remains open. A3. During the heat storage and supply period (such as the stage of simultaneous heat storage and supply by the electrode boiler during off-peak electricity hours: the electrode boiler starts to produce steam, part of which is stored in the spherical tank for heat storage, and the other part is supplied to the outside), the eighth control valve 20, the seventh control valve 19, and the sixth control valve 18 are normally opened to store and supply heat at the same time. When the pressure of the steam accumulator reaches or exceeds the first set value, the high-pressure electrode boiler is shut down, the eighth control valve 20 and the seventh control valve 19 are closed, and the sixth control valve 18 is opened. The energy storage system supplies steam to the outside, and the deaerator remains open. If the pressure drops below the second set value, the high-pressure electrode boiler will automatically start heating, open the eighth control valve 20 and the seventh control valve 19, and close the sixth control valve 18. The steam accumulator's independent heat release mode includes: B1. When the conditions for independent heat release by the steam accumulator are met (such as during peak electricity periods, the independent heating stage of the steam accumulator: the electrode boiler is shut down, and the heat stored in the spherical tank is used for flash steam supply to the outside), the energy storage system supplies steam to the outside alone, the electrode boiler is in the off state, the eighth control valve 20 and the seventh control valve 19 are closed, the sixth control valve 18 is opened, and the deaerator is shut down; until the pressure of the accumulator tank reaches the third set value, the steam accumulator / electrode boiler / gas boiler switching mode is started, the third set value is less than the second set value (in this embodiment, the third set value is set to 0.7MPa); otherwise, other modes are set and operated. B2. The opening of the sixth control valve 18 is automatically adjusted according to the third set value of the steam accumulator pressure (default 0.7Mpa) and the steam distribution cylinder pressure to ensure that the steam distribution cylinder pressure meets the requirements. During peak power periods, in the combined supply phase of the gas-fired boiler / electrode boiler and steam accumulator, when the steam accumulator's output steam load is insufficient, the gas-fired boiler or electrode boiler is activated in conjunction with the steam accumulator to produce steam for external output. During peak power periods, in the independent heating phase of the gas-fired boiler / electrode boiler, after the steam accumulator has finished releasing heat, the gas-fired boiler or electrode boiler is used to independently supply steam for external output. The specific timing can be determined based on the relationship between r / n and d1 and d2, or according to on-site decisions. The switching modes for the steam accumulator / electrode boiler / gas-fired boiler include: C1. Switching between steam accumulator and electrode / gas boiler in heat release mode: When the steam accumulator pressure is less than or equal to the third set value, either the electrode boiler or the gas boiler is turned on (which one is turned on is determined according to the gas supply route). The corresponding eighth control valve 20 or fifth control valve 17 is opened, while the sixth control valve 18 remains open. One of the electrode boilers or the gas boiler works in conjunction with the steam accumulator to supply heat to the outside, and the corresponding deaerator starts simultaneously. This design is to ensure a stable gas supply output from the steam distribution cylinder and avoid gas supply fluctuations caused by directly shutting down the steam accumulator.

[0046] C2. When the steam accumulator pressure drops to the fourth set value, the energy storage system stops supplying steam externally, closes the sixth control valve 18, and the electrode boiler or gas boiler supplies steam externally independently, while the corresponding deaerator continues to operate; the fourth set value is less than the third set value (in this embodiment, the fourth set value is set to 0.6 MPa). The pressure of the electrode boiler or gas boiler and the opening of the control valve are adjusted according to the pressure of the main steam distribution pipe (0.55 ± 0.05 MPa).

[0047] C3. Keep the electrode boiler or gas boiler running until the steam demand deadline is reached, then stop or switch modes according to the new mode settings.

[0048] Based on cost optimization considerations or other user-specific needs, if switching between electrode boilers and gas boilers is required, a method of gradually reducing the output of one while gradually increasing the output of the other is generally adopted. The rate of increase in output pressure of the increasing output side is slightly greater than the rate of decrease in pressure of the reducing output side. This continues until the pressure of the reducing output side drops below the fourth set value, at which point it can be directly shut off. The output pressure of the increasing output side increases to the set threshold, at which point the increase can be stopped. This design avoids the traditional simple strategy of turning one side on and off the other, thereby ensuring stable steam cylinder output and extending the service life of the equipment system.

[0049] Furthermore, the control method may also include a steam accumulator standby mode, which enables the steam accumulator to provide emergency heating. In this mode, a fifth and a sixth setpoint for the steam accumulator pressure are set, with the order being: first setpoint > second setpoint > fifth setpoint > sixth setpoint > third setpoint > fourth setpoint. In this embodiment, the fifth setpoint is set to 1.5 MPa and the sixth setpoint to 1.4 MPa. When the steam accumulator pressure drops to the fifth setpoint, the electrode boiler or gas boiler is activated, and one of the electrode boilers or gas boilers works in conjunction with the steam accumulator to provide external heating, with the corresponding deaerator starting simultaneously. When the steam accumulator pressure drops to the sixth setpoint, the energy storage system stops supplying steam, and the electrode boiler or gas boiler supplies steam solely to the outside. This allows the steam accumulator to retain a certain emergency heating capacity; when emergency heating is needed, the steam accumulator can be activated in a separate heat release mode.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principle of the present invention, such as adding or reducing some control valves, adjusting the configuration of the soft water system and water treatment device (adding or reducing), etc. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A steam heating system based on gas-electricity-storage multi-energy coupling, characterized in that, The heating system includes an electric heating unit, a gas heating unit, a steam storage unit, and a steam supply control unit; The steam heat storage unit includes at least a steam heat storage device (16). The steam supply control unit includes at least a steam distribution cylinder (21), an intelligent control module (1), a fifth control valve (17), a sixth control valve (18), and an eighth control valve (20). The intelligent control module is electrically connected to the control valves and the water pump. The electric heating unit includes at least an electrode boiler (2), a first deaerator (4), and a first water pump (6); the inlet pipe is connected to the first deaerator (4), and the outlet pipe of the first deaerator (4) is connected to the electrode boiler (2) and the steam accumulator (16) via the first water pump (6); the outlet pipe of the electrode boiler (2) is connected to the steam distribution cylinder (21) and the steam accumulator (16) via the eighth control valve (20). The electrode boiler (2) includes an electrode assembly, an inner cylinder, an outer cylinder, and an actuator. A second water pump (7) is provided with its two ends connected to the outer cylinder outlet and the inner cylinder inlet of the electrode boiler, respectively. The gas heating unit includes at least a gas boiler (9), a second deaerator (14) and a fourth water pump (13); the inlet pipe is connected to the second deaerator (14), the outlet pipe of the second deaerator (14) is connected to the gas boiler (9) via the fourth water pump (13), and the outlet of the gas boiler (9) is connected to the steam cylinder (21) via the fifth control valve (17). The steam distribution cylinder (21) is connected to the first deaerator (4) and the second deaerator (14) respectively; the output of the steam accumulator (16) is connected to the steam distribution cylinder (21) via the sixth control valve (18); The flow rate ratio of the second water pump (7) to the flow rate of the first water pump (6) is 1:1 to 1:1.

7.

2. A steam heating system based on gas-electricity-storage multi-energy coupling according to claim 1, characterized in that, The electrode boiler (2) and the steam accumulator (16) are respectively equipped with a second control valve (5) and a third control valve (8) on their water inlet pipes; a seventh control valve (19) is installed on the side of the connection pipe between the eighth control valve (20) and the steam accumulator (16) near the steam accumulator (16); one outlet of the steam distribution cylinder (21) is connected to the first deaerator (4) via the first control valve (3), and the other outlet of the steam distribution cylinder (21) is connected to the second deaerator (14) via the fourth control valve (15).

3. A steam heating system based on gas-electricity-storage multi-energy coupling according to claim 1, characterized in that, A soft water system (11) is installed on the water inlet pipe, and after passing through the third water pump (12), it is connected to the second deaerator (14), and after passing through the water treatment device (10), it is connected to the first deaerator (4).

4. A steam heating system based on gas-electricity-storage multi-energy coupling according to claim 1, characterized in that, The volumetric filling ratio of deoxygenated water in the steam accumulator (16) is 20-90%.

5. A steam heating system based on gas-electricity-storage multi-energy coupling according to claim 1, characterized in that, The heat storage steam pressure in the steam accumulator (16) is 2-4 MPa, and the heat release steam pressure is 0.6-2 MPa, wherein the heat release steam pressure does not exceed the heat storage steam pressure.

6. A steam heating system based on gas-electricity-storage multi-energy coupling according to claim 1, characterized in that, One output of the gas boiler (9) is connected to the steam accumulator (16) via the ninth control valve.

7. A steam heating control method based on gas-electric-storage multi-energy coupling, characterized in that, According to any one of claims 1-6, the steam heating system is characterized by multi-energy coupling through the linkage of a gas boiler, an electrode boiler, and a steam accumulator. When the gas price, off-peak electricity price, and peak electricity price fluctuate, a suitable steam supply route is selected to reduce operating costs for heat users. Let the off-peak electricity price be d1 yuan / kWh, the peak electricity price be d2 yuan / kWh (d2 > d1), and the price of 1 cubic meter of natural gas be r yuan / kWh, and its calorific value be equal to the electricity consumption of n kWh. When r / n < d1, a gas-fired boiler is used for heating; When r / n > d2, a coupled heating system of electrode boiler and steam accumulator is used. When d1≤r / n≤d2, a coupled heating system of gas boiler, electrode boiler and steam accumulator is adopted. During off-peak hours, a coupled heating mode of electrode boiler heating and steam accumulator heat storage is adopted. During peak hours, a combined heating mode of gas boiler and steam accumulator is adopted, with priority given to steam accumulator heating. When the heat of steam accumulator is insufficient, gas boiler heating is adopted.

8. A steam heating control method based on gas-electric-storage multi-energy coupling according to claim 7, characterized in that, The control methods include a heat storage mode, a steam accumulator-only heat release mode, and a steam accumulator / electrode boiler / gas boiler switching mode.

9. A steam heating control method based on gas-electric-storage multi-energy coupling according to claim 8, characterized in that, The heat storage mode includes: A1. When the heat storage conditions are met, the heat storage mode is activated; A2. During the heat storage period, when the pressure of the steam accumulator reaches or exceeds the first set value, the high-pressure electrode boiler stops. If the pressure of the steam accumulator drops to the second set value, the electrode boiler will automatically start heating, and the second set value is less than the first set value. A3. During the heat storage and supply period, when the pressure of the steam accumulator reaches or exceeds the first set value, the high-pressure electrode boiler is shut down, the energy storage system supplies steam to the outside, and the deaerator remains open. If the pressure drops below the second set value, the high-pressure electrode boiler will automatically start heating. The steam accumulator's independent heat release mode includes: B1. When the conditions for independent heat release of the steam accumulator are met, the energy storage system supplies steam to the outside alone, the electrode boiler is in the closed state, and the deaerator is shut down; until the pressure of the accumulator tank reaches the third set value, the steam accumulator / electrode boiler / gas boiler switching mode is activated, and the third set value is less than the second set value. B2. The opening of the sixth control valve is automatically adjusted according to the third set value of the steam accumulator pressure and the pressure of the steam distribution cylinder. The switching modes for steam accumulator / electrode boiler / gas boiler include: C1. Switching between steam accumulator and electrode boiler / gas boiler in heat release mode: When the steam accumulator pressure is less than or equal to the third set value, the electrode boiler or gas boiler is turned on, and one of the electrode boiler or gas boiler and the steam accumulator jointly supply heat to the outside, and the corresponding deaerator is started at the same time. C2. When the pressure of the steam accumulator drops to the fourth set value, the energy storage system stops supplying steam to the outside, and the electrode boiler or gas boiler supplies steam to the outside alone, while the corresponding deaerator continues to operate; the fourth set value is less than the third set value. C3. Keep the electrode boiler or gas boiler running until the steam demand cutoff time is reached, then stop or switch modes according to the new mode settings; If it is necessary to switch between electrode boilers and gas boilers, the output of one should be gradually reduced while the output of the other is gradually increased, and the rate of increase of the output pressure of the increasing output side should be greater than the rate of decrease of the output pressure of the decreasing output side. The control method also includes a steam accumulator standby mode, in which a fifth and a sixth setpoint for the steam accumulator pressure are set respectively, with the first setpoint > the second setpoint > the fifth setpoint > the sixth setpoint > the third setpoint > the fourth setpoint; when the steam accumulator pressure drops to the fifth setpoint, the electrode boiler or the gas boiler is turned on, and one of the electrode boiler or the gas boiler is used in conjunction with the steam accumulator to supply heat to the outside, and the corresponding deaerator is started at the same time; when the steam accumulator pressure drops to the sixth setpoint, the energy storage system stops supplying steam to the outside.

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