Heat supply system and control method thereof

Abstract

The invention belongs to the field of heat supply, and discloses a heat supply system and a control method thereof.The heat supply system comprises a secondary reheating unit, a steam distribution unit, an auxiliary machine driving unit and a heat energy comprehensive utilization unit; an ultrahigh-pressure cylinder of the secondary reheating unit is connected with the primary reheating system, an outlet of the primary reheating system is connected with a high-pressure cylinder steam inlet pipeline and a steam utilization pipeline in parallel, a steam auxiliary pipeline is arranged on the steam utilization pipeline, and part of primary reheating steam is divided by controlling the opening degree of the steam auxiliary pipeline so as to achieve unit power adjustment. The steam distribution unit comprises a steam header communicated with the steam auxiliary road; the auxiliary machine driving unit comprises a water feeding pump turbine driven by steam and a steam-driven induced draft fan subsystem, the steam-driven induced draft fan subsystem comprises a small turbine, and the steam distribution unit is configured to provide driving steam for the water feeding pump turbine and the small turbine; the heat energy comprehensive utilization unit comprises a heat supply component connected with the steam distribution unit.

Description

Technical Field

[0001] This invention belongs to the field of heating, and particularly relates to a heating system and its control method. Background Technology

[0002] When traditional coal-fired power generating units participate in deep grid peak shaving, the power generation load needs to be significantly reduced, resulting in a decrease in the unit's extraction steam parameters (pressure, temperature, and flow rate), making it difficult to meet the stable heating needs of surrounding industrial or residential users. This contradiction severely restricts the flexibility of the unit's peak shaving.

[0003] While some related technologies employ a single unit for heating or set up a simple backup boiler, these systems lack flexibility, have low energy efficiency, and struggle to guarantee heating reliability under conditions of low load or malfunction of the main unit. Summary of the Invention

[0004] In view of this, the present invention discloses a heating system and its control method, which can solve the shortcomings of related technologies.

[0005] To achieve the above objectives, the present invention discloses the following technical solution: In one aspect, a heating system is provided, including a secondary reheat unit, a steam distribution unit, an auxiliary machine drive unit, and a thermal energy comprehensive utilization unit; The ultra-high pressure cylinder of the secondary reheat unit is connected to the primary reheat system. The outlet of the primary reheat system is connected in parallel to the steam inlet pipe of the high pressure cylinder and the steam utilization pipe. The steam utilization pipe is equipped with a steam auxiliary path. By controlling the opening of the steam auxiliary path, part of the primary reheat steam is diverted to achieve unit power regulation. The steam distribution unit includes a steam header connected to the auxiliary steam line, used to collect and distribute the diverted steam; The auxiliary machine drive unit includes a steam-driven feedwater pump turbine and a steam-driven induced draft fan subsystem. The steam-driven induced draft fan subsystem includes a small steam turbine. The steam distribution unit is configured to provide drive steam to the feedwater pump turbine and the small steam turbine. The thermal energy utilization unit includes a heating component connected to the steam distribution unit, used to provide steam and hot water to external users.

[0006] Preferably, the steam-driven induced draft fan subsystem is a steam-electric dual-drive structure, including the small steam turbine 7, the electric motor 8, and the induced draft fan 9 which can be driven by both or by one of them. The steam inlet of the small steam turbine 7 is connected to a first steam source or a second steam source. The first steam source is steam from the steam header 5 and processed by the desuperheating and pressure reducing device 6. The second steam source is steam from the auxiliary steam header 14.

[0007] Preferably, the steam distribution unit further includes a heating header 13 and an auxiliary steam header 14; The steam inlet of the heating manifold 13 is connected to the three-stage extraction steam 2-1 and / or the exhaust steam pipe 2-4 of the high-pressure cylinder 2, for collecting heating steam; One of the steam outlets of the heating header 13 is used for external heating 13-1, and the other is connected to the auxiliary steam header 14 through the pipeline 13-2 to provide steam source for the auxiliary steam header 14.

[0008] Preferably, the feedwater pump turbine 15 is equipped with dual steam sources; The first steam source is connected to the extraction steam of the intermediate pressure cylinder 3; The second steam source is connected to the exhaust pipe 2-5 of the high-pressure cylinder 2; The system is configured to use the first steam source when the unit is under high load and switch to the second steam source when the unit is under low load, so as to ensure the power supply of the feedwater pump 16.

[0009] Preferably, the thermal energy comprehensive utilization unit includes a steam-water mixing manifold 17 and a water tank 19; The steam inlet of the steam-water mixing manifold 17 is connected to the auxiliary steam manifold 14 via a pipe 14-2 for receiving heating steam; The inlet of the steam-water mixing manifold 17 is connected to the condensate system, and its outlet is connected to the water tank 19 through the hot water pipe 5-2, for the preparation and storage of hot water.

[0010] Preferably, the thermal energy comprehensive utilization unit further includes a steam heat exchanger tube 10; The steam-side inlet of the steam heat exchanger tube 10 is connected to the steam bypass 5-1 of the steam header 5 for recovering the heat energy of the steam. The water-side passage of the steam heat exchanger 10 is connected between the condenser 11 and the water tank 19, and uses the heat of steam to heat the condensate to supply hot water.

[0011] Preferably, a water pump 19-1 is provided on the outlet pipe of the water tank 19, and branches to form a hot water user pipe 19-2 and a high-pressure heater pipe 19-3; The high-pressure heater pipeline 19-3 is connected to the pipeline before the high-pressure heater 18 at the outlet of the feedwater pump 16; the system is configured to cut off the hot water supply when the unit rapidly increases its load, and to replenish the boiler feedwater system with water from the water tank 19 through the high-pressure heater pipeline 19-3. Secondly, a control method for a heating system is provided, including: Monitor the load demand of the regional power grid; When the grid load decreases, a low-load operation mode is implemented: the steam auxiliary circuit is opened to divert some of the primary reheat steam to the steam header; Steam from the steam header drives a small steam turbine to operate an induced draft fan, and switches the steam source of the feedwater pump turbine to the high-pressure cylinder exhaust steam, as well as diverting steam and waste heat for external heating and hot water supply. When the grid load increases, a load increase operation is performed: the external heating and hot water supply processes are cut off in sequence, and resources are prioritized for power generation to meet the grid power demand.

[0012] Preferably, the low-load operation mode includes: When the unit load is below 30%, the steam auxiliary circuit should remain open. Open the pipeline from the steam header to the desuperheating and pressure reducing device and then to the small steam turbine, and drive the induced draft fan; The steam source of the feedwater pump turbine is switched to the exhaust steam of the high-pressure cylinder.

[0013] Preferably, the method further includes: When the steam demand exceeds the hot water demand, the steam from the heating header is controlled to be output more through the external heating pipeline, so as to reduce the amount of steam going to the auxiliary steam header. When the demand for hot water exceeds the demand for steam, the amount of steam flowing to the auxiliary steam header is increased to increase the amount of steam entering the steam-water mixing header and thus increase the hot water production.

[0014] Compared with the prior art, the present invention has the following beneficial effects: On the one hand, the diversion control of the steam auxiliary circuit enables flexible adjustment of the unit's power, allowing for rapid response to changes in grid load and meeting the needs of deep peak shaving. On the other hand, both the feedwater pump turbine and the induced draft fan adopt a steam-driven or steam-electric dual-drive structure, ensuring power supply to key auxiliary equipment even at low loads, thus improving the stability and reliability of unit operation. Furthermore, the multi-level header system, including steam headers, heating headers, and auxiliary steam headers, enables cascaded utilization and flexible distribution of steam, using diverted steam and waste heat for heating and hot water supply, improving overall energy efficiency. In addition, the installation of the pipeline from the water tank to the high-pressure heater allows for rapid replenishment of water stored in the hot water system to the boiler feedwater system when rapid load increase is required, shortening the load increase time and improving the unit's response speed. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a heating system provided in an exemplary embodiment; Figure 2 This is a flowchart of a control method for a heating system provided in an exemplary embodiment.

[0016] The diagram is marked 1-Ultra-high pressure cylinder, 1-1-Single reheat system, 1-2-Steam utilization pipeline, 1-3-Steam inlet pipeline to high-pressure cylinder, 1-4-Steam auxiliary line, 2-High pressure cylinder, 2-1-Three-stage extraction steam, 2-2-High pressure cylinder exhaust steam, 2-3-Secondary reheat system, 2-4-High pressure cylinder exhaust steam pipeline, 2-5-High pressure cylinder exhaust steam pipeline, 2-7-High pressure cylinder exhaust steam pipeline, 3-Intermediate pressure cylinder, 4-Low pressure cylinder, 5-Steam header, 5-1-Steam bypass, 5-2-Hot water pipeline, 6-Desuperheating and pressure reducing device, 6-1-Pipeline to small steam turbine, 7-Small steam turbine, 8-Electric motor, 9 10-Induced draft fan, 11-Steam heat exchange tube, 12-Condenser, 13-1-Condensate pipeline, 14-Low-pressure heater, 15-Deaerator, 16-External heating pipeline, 17-Pipeline to auxiliary steam header, 18-High-pressure heater, 19-Water tank, 10-1-Water pump, 11-2-Pipeline to hot water user, 19-3-Pipeline to high-pressure heater. Detailed Implementation

[0017] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of the present invention. Rather, they are merely examples of systems consistent with one or more embodiments of the present invention as detailed in the appended claims.

[0018] It should be noted that the steps of the corresponding methods in other embodiments are not necessarily performed in the order shown and described in this invention. In some other embodiments, the methods may include more or fewer steps than those described in this invention. Furthermore, a single step described in this invention may be broken down into multiple steps in other embodiments; and multiple steps described in this invention may be combined into a single step in other embodiments.

[0019] In coupled heating production lines, high-temperature steam or hot water is often used for sterilization. In related technologies, high-temperature steam and hot water are mostly produced using boiler facilities, and the hot water is typically stored in a hot water tank and supplied as needed. However, this method does not utilize the waste heat generated during sterilization, resulting in a waste of high-temperature hot water and increased production costs.

[0020] To address the shortcomings of related technologies, this invention proposes a heating system.

[0021] Figure 1 This is a schematic diagram of a heating system provided in an exemplary embodiment. (See diagram below.) Figure 1 As shown, the heating system includes: a secondary reheat unit, a steam distribution unit, an auxiliary machine drive unit, and a thermal energy comprehensive utilization unit.

[0022] The double reheat unit is the core power source of the system, comprising an ultra-high pressure cylinder 1, a primary reheat system 1-1, a high-pressure cylinder 2, a secondary reheat system 2-3, an intermediate-pressure cylinder 3, and a low-pressure cylinder 4. The exhaust steam from the ultra-high pressure cylinder 1 enters the primary reheat system 1-1 for heating. The outlet of the primary reheat system 1-1 is connected in parallel to the high-pressure cylinder inlet pipe 1-3 and the steam utilization pipe 1-2. The steam utilization pipe 1-2 is equipped with a steam auxiliary path 1-4. By controlling the opening of the steam auxiliary path 1-4, a portion of the primary reheat steam can be diverted to the steam distribution unit, thereby achieving flexible adjustment of the unit's power output. When it is necessary to reduce the unit load, the opening of the steam auxiliary path 1-4 is increased to divert more steam; when it is necessary to increase the unit load, the opening of the steam auxiliary path 1-4 is decreased, allowing more steam to enter the high-pressure cylinder 2 to generate electricity.

[0023] The steam distribution unit includes a steam header 5 connected to the auxiliary steam line 1-4. The steam header 5 is used to collect the steam diverted from the auxiliary steam line 1-4 and distribute the steam to different users as needed. The steam header 5 is equipped with multiple outlets, which are respectively connected to the desuperheating and pressure reducing device 6, the steam heat exchange tube 10, and other equipment to realize multi-stage utilization of steam.

[0024] The auxiliary equipment drive unit includes a steam-driven feedwater pump turbine 15 and a steam-driven induced draft fan subsystem. The feedwater pump turbine 15 drives the feedwater pump 16 to supply water to the boiler. The steam-driven induced draft fan subsystem includes a small steam turbine 7, which drives the induced draft fan 9 via a transmission mechanism. The steam distribution unit is configured to supply driving steam to the feedwater pump turbine 15 and the small steam turbine 7, ensuring that critical auxiliary equipment receives sufficient power even when the unit is operating at low load.

[0025] The thermal energy comprehensive utilization unit includes heating components connected to the steam distribution unit for providing steam and hot water to external users. The heating components include heating header 13, auxiliary steam header 14, steam-water mixing header 17, water tank 19, and other equipment. Through the coordinated operation of these devices, the diverted steam and waste heat are used for external heating and hot water supply, thereby improving energy utilization efficiency.

[0026] In this embodiment, the organic combination of four functional units enables flexible adjustment of unit power, reliable drive of key auxiliary equipment, and efficient comprehensive utilization of thermal energy, thus solving the problems of insufficient auxiliary power and low energy utilization efficiency of secondary reheat units during peak operation.

[0027] In one embodiment, the steam-driven induced draft fan subsystem is a dual-drive structure, including the small steam turbine 7, the electric motor 8, and the induced draft fan 9 which can be driven by both or one of them; the steam inlet of the small steam turbine 7 is connected to a first steam source or a second steam source, the first steam source is steam from the steam header 5 and processed by the desuperheating and pressure reducing device 6, and the second steam source is steam from the auxiliary steam header 14.

[0028] The steam-driven induced draft fan subsystem is a dual-drive structure, comprising a small steam turbine 7, an electric motor 8, and an induced draft fan 9 that can be driven by both or one of them. The shaft of the induced draft fan 9 is connected to the small steam turbine 7 and the electric motor 8 via a clutch or coupling, allowing for selection of drive by the small steam turbine 7, the electric motor 8, or both, depending on operating conditions. The steam inlet of the small steam turbine 7 is connected to either a first steam source or a second steam source. The first steam source is steam from the steam header 5, processed by the desuperheating and pressure reducing device 6. Steam from the steam header 5 enters the desuperheating and pressure reducing device 6 via a steam bypass 5-1, and after desuperheating and pressure reducing, enters the small steam turbine 7 via a pipe 6-1 to the small steam turbine. The second steam source is steam from the auxiliary steam header 14. The auxiliary steam header 14 is connected to the small steam turbine 7 via a steam pipe 14-1 to the steam-driven induced draft fan, providing a backup steam source for the small steam turbine 7.

[0029] In this embodiment, the reliability of the induced draft fan system is improved through a dual-drive structure. Under high unit load, the induced draft fan 9 can be driven by the electric motor 8, reducing steam consumption; under low unit load, the induced draft fan 9 can be driven by the small steam turbine 7, saving plant power. The dual steam source design ensures that the small steam turbine 7 can obtain sufficient driving steam under any operating condition, improving the system's operational reliability.

[0030] Furthermore, the steam distribution unit also includes a heating header 13 and an auxiliary steam header 14; the steam inlet of the heating header 13 is connected to the three-stage extraction steam 2-1 of the high-pressure cylinder 2 and / or the exhaust steam pipe 2-4 of the high-pressure cylinder, for collecting heating steam; one of the steam outlets of the heating header 13 is used for external heating 13-1, and the other is connected to the auxiliary steam header 14 through pipe 13-2 to provide steam source for the auxiliary steam header 14.

[0031] The steam distribution unit also includes a heating header 13 and an auxiliary steam header 14. The steam inlet of the heating header 13 is connected to the three-stage extraction steam 2-1 of the high-pressure cylinder 2 and / or the exhaust steam pipe 2-4 of the high-pressure cylinder, for collecting heating steam. The three-stage extraction steam 2-1 and the exhaust steam 2-2 of the high-pressure cylinder 2 are both high-grade steam, suitable for external heating.

[0032] One steam outlet of the heating header 13 is used for external heating 13-1, directly providing steam to heat users; the other outlet is connected to the auxiliary steam header 14 via pipeline 13-2, providing steam for the auxiliary steam header 14. The auxiliary steam header 14 is used to collect steam from the heating header 13 and distribute the steam to users such as the small steam turbine 7 and the steam-water mixing header 17 as needed.

[0033] In this embodiment, by setting up a heating header 13 and an auxiliary steam header 14, the cascade utilization and flexible distribution of steam are realized. The three-stage extraction steam 2-1 of the high-pressure cylinder 2 and the exhaust steam 2-2 of the high-pressure cylinder first enter the heating header 13. Part of it is directly supplied to the outside for heating, and the other part enters the auxiliary steam header 14 to drive auxiliary machines or heat hot water, thus realizing the rational distribution and efficient utilization of steam.

[0034] Furthermore, the feedwater pump turbine 15 is equipped with dual steam sources; the first steam source is connected to the extraction steam of the intermediate pressure cylinder 3; the second steam source is connected to the exhaust steam pipe 2-5 of the high pressure cylinder 2; the system is configured to use the first steam source when the unit is under high load, and switch to the second steam source when the unit is under low load, so as to ensure the power supply of the feedwater pump 16.

[0035] The feedwater pump turbine 15 is equipped with dual steam sources. The first steam source is connected to the extraction steam of the intermediate-pressure cylinder 3. The extraction steam pressure of the intermediate-pressure cylinder 3 is moderate, suitable for driving the feedwater pump turbine 15 under high unit load. The second steam source is connected to the exhaust steam pipe 2-5 of the high-pressure cylinder 2. The exhaust steam pressure of the high-pressure cylinder 2 is higher, suitable for driving the feedwater pump turbine 15 under low unit load.

[0036] The system is configured to use the first steam source, namely the extraction steam from the intermediate-pressure cylinder 3, when the unit is under high load; and switch to the second steam source, namely the exhaust steam from the high-pressure cylinder 2, when the unit is under low load, to ensure the power supply to the feedwater pump 16. When the unit is operating at low load, the extraction steam pressure of the intermediate-pressure cylinder 3 decreases, which may not be able to meet the steam inlet requirements of the feedwater pump turbine 15. At this time, switching to the exhaust steam from the high-pressure cylinder 2 can ensure that the feedwater pump 16 receives sufficient power and ensures the normal supply of boiler feedwater.

[0037] In this embodiment, the problem of insufficient power for the feedwater pump during low-load operation is solved by the dual-steam source design of the feedwater pump turbine 15. When the unit is under low load, switching to the exhaust steam from the high-pressure cylinder 2 ensures the normal operation of the feedwater pump 16, improving the reliability and stability of the unit's operation.

[0038] In one embodiment, the thermal energy utilization unit includes a steam-water mixing manifold 17 and a water tank 19; the steam inlet of the steam-water mixing manifold 17 is connected to the auxiliary steam manifold 14 via a pipe 14-2 for receiving heating steam; the water inlet of the steam-water mixing manifold 17 is connected to the condensate system, and its outlet is connected to the water tank 19 via a hot water pipe 5-2 for preparing and storing hot water.

[0039] The thermal energy utilization unit includes a steam-water mixing header 17 and a water tank 19. The steam inlet of the steam-water mixing header 17 is connected to the auxiliary steam header 14 via a pipe 14-2, and is used to receive steam for heating. The steam from the auxiliary steam header 14 enters the steam-water mixing header 17 through the pipe 14-2, and mixes with the condensate for heating.

[0040] The inlet of the steam-water mixing header 17 is connected to the condensate system, with condensate sourced from the condenser 11 or condensate line 11-1. The outlet of the steam-water mixing header 17 is connected to the water tank 19 via the hot water line 5-2 for the preparation and storage of hot water. In the steam-water mixing header 17, steam and condensate are directly mixed, heating the condensate to the required temperature, and then it is transported to the water tank 19 via the hot water line 5-2 for storage and user use.

[0041] In this embodiment, hot water preparation and storage are achieved by setting up a steam-water mixing manifold 17 and a water tank 19. Steam from the auxiliary steam manifold 14 is used to heat the condensate, producing hot water for user consumption, thus improving energy efficiency while meeting the user's heating needs. Furthermore, the thermal energy comprehensive utilization unit also includes a steam heat exchange tube 10; the steam-side inlet of the steam heat exchange tube 10 is connected to the steam bypass 5-1 of the steam header 5 for recovering the thermal energy of the steam; the water-side passage of the steam heat exchange tube 10 is connected between the condenser 11 and the water tank 19 to use the heat of the steam to heat the condensate to supply hot water.

[0042] The thermal energy utilization unit also includes a steam heat exchanger tube 10. The steam-side inlet of the steam heat exchanger tube 10 is connected to the steam bypass 5-1 of the steam header 5 for recovering the thermal energy of the steam. The steam from the steam header 5 enters the steam side of the steam heat exchanger tube 10 through the steam bypass 5-1, releases heat, and condenses into water.

[0043] The water-side passage of the steam heat exchanger tube 10 is connected between the condenser 11 and the water tank 19, using the heat of steam to heat the condensate to supply hot water. The condensate of the condenser 11 enters the water side of the steam heat exchanger tube 10 through the condensate pipe 11-1, absorbs the heat of steam and is heated, and then is transported to the water tank 19 for storage and use by users.

[0044] In this embodiment, by setting up steam heat exchange tube 10, the thermal energy of the steam is further recovered, improving energy utilization efficiency. The steam heat exchange tube 10 adopts an indirect heat exchange method, so the steam and condensate do not come into direct contact, avoiding water pollution, while achieving effective heat transfer.

[0045] In one embodiment, a water pump 19-1 is provided on the outlet pipe of the water tank 19, and branches to form a hot water user pipe 19-2 and a high-pressure heater pipe 19-3; the high-pressure heater pipe 19-3 is connected to the pipe before the high-pressure heater 18 at the outlet of the feedwater pump 16; the system is configured to cut off the hot water supply when the unit rapidly increases the load, and replenish the water in the water tank 19 to the boiler feedwater system through the high-pressure heater pipe 19-3.

[0046] A water pump 19-1 is installed on the outlet pipe of water tank 19, and branches to form a hot water user pipe 19-2 and a high-pressure heater pipe 19-3. Water pump 19-1 is used to transport hot water from water tank 19 to users or to supplement the boiler feedwater system.

[0047] The high-pressure heater pipe 19-3 connects to the pipe before the high-pressure heater 18 at the outlet of the feedwater pump 16. The system is configured to cut off the hot water supply and replenish the boiler feedwater system with water from the tank 19 via the high-pressure heater pipe 19-3 when the unit rapidly increases its load. When the unit needs to rapidly increase its load, the boiler feedwater demand increases. At this time, the hot water user pipe 19-2 can be cut off, and the water stored in the tank 19 can be quickly replenished to the boiler feedwater system via the high-pressure heater pipe 19-3, shortening the load increase time.

[0048] In this embodiment, the linkage between the hot water system and the boiler feedwater system is achieved by setting up the high-pressure heater pipe 19-3. When the unit needs to rapidly increase its load, the water stored in the water tank 19 can be used to quickly replenish the boiler feedwater, improving the unit's response speed and meeting the grid peak-shaving requirements.

[0049] Accordingly, the present invention also proposes a control method for a heating system.

[0050] Figure 2 This is a flowchart illustrating a control method for a heating system as provided in an exemplary embodiment. Figure 2 As shown, the method includes at least the following steps: Step 201: Monitor the load demand of the regional power grid.

[0051] By monitoring the load changes of the power grid in real time through the power grid dispatching system or the unit control system, the operating conditions of the unit can be determined. Step 202: When the grid load decreases, execute the low load operation mode: open the steam auxiliary circuit 1-4 to divert some of the primary reheat steam to the steam header 5; drive the small steam turbine 7 through the steam header 5 to run the induced draft fan 9, switch the steam source of the feedwater pump turbine 15 to the high-pressure cylinder exhaust steam, and use the diverted steam and waste heat for external heating and hot water supply. Step 203: When the grid load increases, perform load increase operation: sequentially cut off the external heating and hot water supply processes, and prioritize the use of resources for power generation to meet the grid power demand.

[0052] First, disconnect the external heating pipeline 13-1 to stop external heating; then disconnect the hot water user pipeline 19-2 to stop hot water supply; finally, gradually close the steam auxiliary pipeline 1-4 to allow more steam to enter the high-pressure cylinder 2 to generate electricity.

[0053] In this embodiment, flexible peak shaving and heating of the unit are achieved by monitoring the grid load and executing corresponding control strategies. Under low load conditions, diverted steam is used to drive auxiliary equipment and provide heating, improving energy utilization efficiency; under high load conditions, power generation is prioritized to meet the grid power demand, thereby improving the unit's peak shaving capability and operating economy.

[0054] In one embodiment, the low-load operation mode includes: when the unit load is below 30%, keeping the steam auxiliary circuit 1-4 open; opening the pipeline 6-1 from the steam header 5 to the desuperheating and pressure reducing device 6 and then to the small steam turbine 7, and driving the induced draft fan 9; switching the steam source of the feedwater pump turbine 15 to the high-pressure cylinder exhaust.

[0055] In this embodiment, specific load thresholds and control logic ensure the safe and stable operation of the unit under low load conditions. By switching the steam source of the feedwater pump turbine and using diverted steam to drive the induced draft fan, the problem of insufficient auxiliary power under low load conditions is solved, thus improving the operational reliability of the unit.

[0056] In one embodiment, the heat output mode can be dynamically adjusted according to the needs of external users. The method further includes: when the steam demand is greater than the hot water demand, controlling the steam of the heating header 13 to be output more through the external heating pipeline 13-1, so as to reduce the amount of steam going to the auxiliary steam header 14; when the hot water demand is greater than the steam demand, increasing the amount of steam going to the auxiliary steam header 14, so as to increase the amount of steam entering the steam-water mixing header 17 and increase the hot water production.

[0057] The heat output method is dynamically adjusted according to external user demand: when steam demand exceeds hot water demand, more steam from the heating header 13 is output through the external heating pipeline 13-1 to reduce the amount of steam going to the auxiliary steam header 14; when hot water demand exceeds steam demand, the amount of steam going to the auxiliary steam header 14 is increased to increase the amount of steam entering the steam-water mixing header 17 and thus increase hot water production. Specifically, the steam distribution ratio can be controlled by adjusting the valve opening at the outlet of the heating header 13. When steam demand is high, the valve opening of the external heating pipeline 13-1 is increased, while the valve opening of the auxiliary steam header pipeline 13-2 is decreased; when hot water demand is high, the valve opening of the external heating pipeline 13-1 is decreased, while the valve opening of the auxiliary steam header pipeline 13-2 is increased, allowing more steam to enter the auxiliary steam header 14, and then through pipeline 14-2 into the steam-water mixing header 17 to heat the hot water. In this embodiment, the adaptability and economy of the system are improved by dynamically adjusting the heat output form. The system can flexibly adjust the output ratio of steam and hot water according to the actual needs of users, which not only meets the users' heat demand, but also improves energy utilization efficiency, and realizes the comprehensive optimization of cogeneration.

[0058] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The foregoing has described specific embodiments of the invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0060] The terminology used in one or more embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in one or more embodiments of the invention and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0061] It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of the present invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0062] The above description is merely a preferred embodiment of one or more embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the protection scope of one or more embodiments of the present invention.

Claims

1. A heating system, characterized in that The system comprises a double-reheat unit, a steam distribution unit, an auxiliary machine driving unit and a heat energy comprehensive utilization unit; The ultra-high pressure cylinder (1) of the double-reheat unit is connected with a primary reheat system (1-1), the outlet of the primary reheat system (1-1) is connected in parallel with a high-pressure cylinder inlet steam pipeline (1-3) and a steam utilization pipeline (1-2), a steam auxiliary path (1-4) is arranged on the steam utilization pipeline (1-2), and the opening degree of the steam auxiliary path (1-4) is controlled to split part of the primary reheat steam to realize unit power regulation. The steam distribution unit comprises a steam header (5) communicated with the steam auxiliary path (1-4) and used for collecting and distributing the split steam. The auxiliary machine driving unit comprises a feed water pump turbine (15) and a steam-driven induced draft fan subsystem, the steam-driven induced draft fan subsystem comprises a small steam turbine (7), and the steam distribution unit is configured to provide driving steam for the feed water pump turbine (15) and the small steam turbine (7). The heat energy comprehensive utilization unit comprises a heat supply component connected with the steam distribution unit and used for providing steam and hot water externally.

2. The system of claim 1, wherein, The steam-driven induced draft fan subsystem is a steam-electric dual driving structure and comprises the small steam turbine (7), an electric motor (8) and an induced draft fan (9) driven by the small steam turbine (7) and the electric motor (8) jointly or selectively. The steam inlet end of the small steam turbine (7) is connected to a first steam source or a second steam source, the first steam source is steam from the steam header (5) and processed by a desuperheating and pressure reducing device (6), and the second steam source is steam from an auxiliary steam header (14).

3. The system of claim 2, wherein, The steam distribution unit further comprises the auxiliary steam header (14) and a heat supply header (13); The steam inlet end of the heat supply header (13) is connected with three-stage extraction steam (2-1) of the high-pressure cylinder (2) and / or a high-pressure cylinder exhaust pipeline (2-4) and used for collecting heat supply steam. The steam outlet end of the heat supply header (13) is used for external heat supply (13-1) in one way and is communicated with the auxiliary steam header (14) through a pipeline (13-2) in another way to provide a steam source for the auxiliary steam header (14).

4. The system of claim 3, wherein, The feed water pump turbine (15) is configured with double steam sources; The first steam source is connected to extraction steam of a medium-pressure cylinder (3); The second steam source is connected to an exhaust pipeline (2-5) of the high-pressure cylinder (2); The system is configured to use the first steam source when the unit is under high load and to switch to the second steam source when the unit is under low load to ensure power supply for a feed water pump (16).

5. The system of claim 3, wherein, The heat energy comprehensive utilization unit comprises a steam-water mixing header (17) and a water tank (19); The steam inlet of the steam-water mixing header (17) is connected with the auxiliary steam header (14) through a pipeline (14-2) and used for receiving heating steam; The water inlet of the steam-water mixing header (17) is connected with a condensate water system, and the outlet thereof is connected with the water tank (19) through a hot water pipeline (5-2) and used for preparing and storing hot water.

6. The system of claim 5, wherein, The heat energy comprehensive utilization unit further comprises a steam heat exchange pipeline (10). The steam side inlet of the steam heat exchange pipe (10) is connected with the steam bypass (5-1) of the steam header (5) for recovering the heat energy of steam. The water side passage of the steam heat exchange pipe (10) is connected between the condenser (11) and the water tank (19) to heat the condensed water by steam heat to supply hot water.

7. The system of claim 5, wherein, The outlet pipeline of the water tank (19) is provided with a water pump (19-1) and branches to form a hot water user pipeline (19-2) and a high pressure heater pipeline (19-3). The high pressure heater pipeline (19-3) is connected to the pipeline before the high pressure heater (18) at the outlet of the feed water pump (16); and the system is configured to cut off the hot water supply when the unit rapidly increases the load, and to supply the water in the water tank (19) to the boiler feed water system through the high pressure heater pipeline (19-3).

8. A control method of a heating system, characterized by, Comprising: Monitoring the load demand of the regional power grid; When the power grid load is reduced, a low load operation mode is performed: the steam bypass is opened to divert part of the primary reheat steam to the steam header; the steam in the steam header drives the small steam turbine to operate the induced draft fan, and the steam source of the feed water pump turbine is switched to the high pressure cylinder exhaust steam, and the diverted steam and waste heat are used for external heat supply and hot water supply; When the power grid load is increased, an ascending load operation is performed: the external heat supply and hot water supply processes are sequentially cut off, and the resources are preferentially used for power generation to meet the power grid power demand.

9. The method of claim 8, wherein, The low load operation mode comprises: When the unit load is less than 30%, the steam bypass is kept open; The pipeline from the steam header to the desuperheating and pressure reducing device to the small steam turbine is opened, and the induced draft fan is driven; The steam source of the feed water pump turbine is switched to the high pressure cylinder exhaust steam.

10. The method of claim 8, wherein, The method further comprises: When the steam demand is greater than the hot water demand, the steam of the heat supply header is controlled to be more output through the external heat supply pipeline to reduce the amount of steam to the auxiliary steam header; When the hot water demand is greater than the steam demand, the amount of steam to the auxiliary steam header is increased to increase the steam into the steam-water mixing header to increase the hot water production.

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