Multi-section air exhaust system of steam turbine

Abstract

The invention discloses a multi-section air exhaust system of a steam turbine, and relates to the technical field of power plant steam utilization. The system is technically characterized by comprising a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder and a steam turbine low-pressure cylinder which are connected with a heat supply boiler, and a steam outlet of the steam turbine low-pressure cylinder, a steam extraction opening of the steam turbine intermediate-pressure cylinder and a steam extraction opening of the steam turbine high-pressure cylinder are connected with a heat storage module of a heat supply system through a first pipeline, a second pipeline and a third pipeline respectively; the heat storage module is used for providing heat energy necessary for heating for heat supply network users in the heat supply system, and the heat storage module and the heat supply boiler are also arranged in the power plant. According to the steam turbine heat storage module, steam exhausted by the low-pressure cylinder of the steam turbine is used, steam extracted from the medium-pressure cylinder of the steam turbine and steam extracted from the high-pressure cylinder of the steam turbine are utilized, in this way, the steam and the steam exhausted by the low-pressure cylinder of the steam turbine are mutually matched to jointly provide heat energy for the heat storage module, and compared with heat supply purely relying on the steam exhaust, the stability of the using process is obviously higher.

Description

Technical Field

[0001] The present application relates to the technical field of steam utilization in power plants, and in particular to a multi-stage exhaust system for a steam turbine. Background Art

[0002] Generally, power plants use condensing units to produce electricity to supply users. Heat for industrial production and people's daily life is supplied separately by special industrial boilers and heating boiler rooms. This energy production method is called heat and electricity separation. In recent years, with the call of energy conservation and emission reduction policies, in order to improve the adaptability of large-scale thermal power direct air-cooled units to meteorological conditions and changes in power generation load, the use of high back pressure heating technology of steam turbines has begun to gain attention in recent years. For example, common thermal power plants use steam extraction or exhaust steam from steam turbines to provide heat to users while generating electricity. In thermal power plants, heating units are used. In addition to supplying electricity, they also use the exhaust steam of steam turbines that have done work (i.e. generated electricity) to meet the heat required for production and life. This energy production method is called cogeneration.

[0003] However, the heat energy commonly used to heat the water supply of the heating system in power generation enterprises is mainly derived from the low-pressure cylinder. This is because the steam generated by the boiler heating in the power plant during the power generation process will first enter the high-pressure cylinder of the steam turbine, and after being discharged from the high-pressure cylinder of the steam turbine, it will re-enter the boiler to heat the steam. The heated steam will enter the medium-pressure cylinder. After being discharged from the medium-pressure cylinder, the steam will directly enter the low-pressure cylinder until it becomes exhaust steam and is discharged from the low-pressure cylinder to the air-cooling tower. Since the steam discharged from the low-pressure cylinder is the last step of the thermal power plant, it is also the simplest and most convenient way to directly heat the water supply of the heating system with the exhaust steam discharged from the low-pressure cylinder. However, thermal power plants usually use exhaust steam to heat the water in the power plant to a specific high temperature first, and then supply the high-temperature hot water to each user community. Each community then uses the hot water transmitted by the thermal power plant through the water-water heat exchange heater in the community to heat the heating water for residents in the community to a temperature suitable for their own community. After these waters flow to each household in the community, the heating effect can be achieved. Since exhaust steam itself is low-grade thermal energy and contains little heat, relying solely on exhaust steam to provide heat is not very stable in reality. When the exhaust steam heat is insufficient, insufficient heating may easily occur. Summary of the invention

[0004] The present application provides a steam turbine multi-stage exhaust system, which can effectively improve the stability during heating.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0006] A steam turbine multi-stage air extraction system comprises a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder and a steam turbine low-pressure cylinder connected to a heating boiler, wherein the steam outlet of the steam turbine low-pressure cylinder, the steam extraction outlet of the steam turbine intermediate-pressure cylinder and the steam extraction outlet of the steam turbine high-pressure cylinder are respectively connected to a heat storage module of the heating system through a first pipeline, a second pipeline and a third pipeline, wherein the heat storage module is used to provide heat energy necessary for heating to heat network users in the heating system, and the heat storage module and the heating boiler are both arranged inside a power plant.

[0007] Furthermore, a fourth pipeline is connected to the first pipeline through a tee, a steam mixing device is provided between the second pipeline and the heat storage module, the fourth pipeline and the second pipeline are connected to the heat storage module through the steam mixing device, and the steam mixing device can pressurize and increase the temperature of the exhaust steam in the first pipeline through the steam in the second pipeline.

[0008] Furthermore, the steam mixing device is a steam booster, the second pipeline is connected to the high-pressure steam inlet of the steam booster at one end away from the intermediate-pressure cylinder of the steam turbine, the fourth pipeline is connected to the induced fluid inlet of the steam booster at one end away from the second pipeline, and the mixed steam outlet of the steam booster is connected to the heat storage module through a fifth pipeline.

[0009] Furthermore, the heat storage module includes a primary heat exchange unit, a secondary heat exchange unit and a tertiary heat exchange unit connected in series in sequence, and the primary heat exchange unit, the secondary heat exchange unit and the tertiary heat exchange unit are respectively connected to the first pipeline, the fifth pipeline and the third pipeline.

[0010] Furthermore, the primary heat exchange unit is a pre-condenser, and the secondary heat exchange unit is a steam booster condenser. The steam inlet of the pre-condenser is connected to the end of the first pipeline away from the low-pressure cylinder of the steam turbine, and the air inlet end of the steam booster condenser is connected to the end of the fifth pipeline away from the steam booster; the water inlet end of the pre-condenser is connected to the return pipe of the heating network user, and the water outlet end of the pre-condenser is connected to the water inlet end of the steam booster condenser through a water pipe.

[0011] Furthermore, the three-stage heat exchange unit is a heat network heater, the steam inlet of the heat network heater is connected to the end of the third pipeline away from the high-pressure cylinder of the turbine, the water outlet end of the steam booster condenser is connected to the water inlet end of the heat network heater through a water pipe, and the water outlet end of the heat network heater delivers hot water to the heat network users through the water pipe.

[0012] Furthermore, a heat network circulation pump is installed on the pipeline between the steam booster condenser and the heat network heater.

[0013] Furthermore, a sixth pipeline is externally connected to the first pipeline at the upstream pipe section of the connection between the first pipeline and the fourth pipeline through a tee, and the sixth pipeline is connected to the steam inlet of the air-cooled condenser at one end away from the first pipeline; a first solenoid valve is installed on the first pipeline, and the first solenoid valve is located on the pipe section of the first pipeline between the connection point between the first pipeline and the sixth pipeline and the connection point between the first pipeline and the fourth pipeline; a second solenoid valve is installed on the sixth pipeline, a third solenoid valve is installed on the second pipeline, and a fourth solenoid valve is installed on the third pipeline.

[0014] Furthermore, a molten salt heat storage system is installed on the sixth pipeline.

[0015] Furthermore, the pre-condenser and the steam booster condenser are both hybrid condensers.

[0016] In summary, the present application includes at least one of the following beneficial technical effects:

[0017] In the present application, a heat storage module for providing heat energy necessary for heating users of the heat network is arranged inside the power plant. The steam outlet of the low-pressure cylinder of the steam turbine, the steam extraction outlet of the intermediate-pressure cylinder of the steam turbine and the steam extraction outlet of the high-pressure cylinder of the steam turbine in the power plant are respectively connected to the heat storage module through the first pipeline, the second pipeline and the third pipeline. Since these devices are all located in the power plant, the steam exhausted from the low-pressure cylinder of the steam turbine, the intermediate-pressure cylinder of the steam turbine and the high-pressure cylinder of the steam turbine can quickly and efficiently enter the heat storage module to provide heat energy for heating. In the process of providing heat energy to the heat storage module, in addition to using the exhaust steam exhausted from the low-pressure cylinder of the steam turbine, the present application also utilizes some steam extracted from the intermediate-pressure cylinder of the steam turbine and the high-pressure cylinder of the steam turbine, so that the exhaust steam exhausted from the low-pressure cylinder of the steam turbine cooperates with each other to provide heat energy for the heat storage module. Compared with simply relying on exhaust steam for heating, the stability of the use process will be obviously higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic diagram of the overall structure of this application system;

[0020] Figure 2 is Figure 1A schematic diagram of a system structure in which a sixth pipeline is connected to the first pipeline, a wind condenser is connected through the sixth pipeline, and a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve are installed on the first pipeline, the sixth pipeline, the second pipeline and the third pipeline respectively;

[0021] Figure 3 is Figure 2 The overall structural diagram of the molten salt heat storage system is added on the basis of the molten salt heat storage system.

[0022] Figure numerals: 1. boiler; 2. turbine high-pressure cylinder; 3. turbine intermediate-pressure cylinder; 4. turbine low-pressure cylinder; 5. first pipeline; 6. second pipeline; 7. third pipeline; 8. heat storage module; 81. primary heat exchange unit; 82. secondary heat exchange unit; 83. tertiary heat exchange unit; 9. fourth pipeline; 10. steam mixing equipment; 11. fifth pipeline; 12. heat network circulation pump; 13. sixth pipeline; 14. air condenser; 15. first solenoid valve; 16. second solenoid valve; 17. third solenoid valve; 18. fourth solenoid valve; 19. molten salt heat storage system. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0024] like Figure 1 As shown, a steam turbine multi-stage extraction system disclosed in the present application includes a steam turbine high-pressure cylinder 2, a steam turbine intermediate-pressure cylinder 3 and a steam turbine low-pressure cylinder 4 connected to a heating boiler 1. The steam outlet of the steam turbine low-pressure cylinder 4, the steam extraction port of the steam turbine intermediate-pressure cylinder 3 and the steam extraction port of the steam turbine high-pressure cylinder 2 are respectively connected to a heat storage module 8 of the heating system through a first pipeline 5, a second pipeline 6 and a third pipeline 7. The heat storage module 8 is used to provide the heat energy required for heating for the heating network users in the heating system. The heat storage module 8 and the heating boiler 1 are also arranged inside the power plant.

[0025] In the above embodiments, the present application sets the heat storage module 8 for providing heat energy necessary for heating for the users of the heat network inside the power plant. The steam outlet of the low-pressure cylinder 4 of the steam turbine, the steam extraction port of the intermediate-pressure cylinder 3 of the steam turbine and the steam extraction port of the high-pressure cylinder 2 of the steam turbine in the power plant are respectively connected to the heat storage module 8 through the first pipeline 5, the second pipeline 6 and the third pipeline 7. Since these devices are all located in the power plant, the steam discharged from the low-pressure cylinder 4 of the steam turbine, the intermediate-pressure cylinder 3 of the steam turbine and the high-pressure cylinder 2 of the steam turbine can quickly and efficiently enter the heat storage module 8 to provide heat energy for heating. In the process of providing heat energy to the heat storage module 8, in addition to using the exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine, the present application also utilizes some steam extracted from the intermediate-pressure cylinder 3 of the steam turbine and the high-pressure cylinder 2 of the steam turbine, so that the exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine cooperates with each other to provide heat energy for the heat storage module 8. Compared with simply relying on the exhaust steam for heating, the stability of the use process will be obviously higher.

[0026] Furthermore, if Figure 1 As shown, the first pipeline 5 is connected to the fourth pipeline 9 through a tee, a steam mixing device 10 is provided between the second pipeline 6 and the heat storage module 8, the fourth pipeline 9 and the second pipeline 6 are connected to the heat storage module 8 through the steam mixing device 10, and the steam mixing device 10 can pressurize and increase the temperature of the exhaust steam in the first pipeline 5 through the steam in the second pipeline 6.

[0027] In the above embodiments, the temperature and pressure of the exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine are usually low, the temperature is usually below 100°C, and the pressure is close to normal pressure. It is generally regarded as a low-grade heat source. Since the exhaust steam temperature is low and the gas is relatively dispersed, the efficiency is not very high if it is directly used for heating water. The temperature of the steam in the intermediate-pressure cylinder 3 of the steam turbine is about 400-450°C and the pressure is about 2.5-5.5MPa. The temperature and pressure are much higher than the exhaust steam temperature. Therefore, the present application adds a fourth pipeline 9 to the first pipeline 5, and the fourth pipeline 9 and the second pipeline 6 are connected to the steam mixing device 10 together. In this way, part of the exhaust steam and the steam discharged from the intermediate-pressure cylinder 3 of the steam turbine can be mixed through the steam mixing device 10, and the steam drawn out from the steam extraction port of the intermediate-pressure cylinder 3 of the steam turbine can be used to improve the quality of the exhaust steam, thereby effectively improving the utilization efficiency of the exhaust steam.

[0028] Furthermore, if Figure 1 As shown, the steam mixing device 10 is a steam booster, the second pipe 6 is connected to the high-pressure steam inlet of the steam booster at one end away from the intermediate-pressure cylinder 3 of the steam turbine, the fourth pipe 9 is connected to the ejection fluid inlet of the steam booster at one end away from the second pipe 6, and the mixed steam outlet of the steam booster is connected to the heat storage module 8 through the fifth pipe 11.

[0029] In the above embodiments, the structure of the steam booster mainly includes three parts: nozzle, negative pressure chamber, and venturi tube. The structure is very simple and there is no rotating equipment, which also determines that its cost will be much lower than that of an ordinary heat pump. When in use, the high-quality steam heat source output from the steam extraction port of the steam turbine intermediate pressure cylinder 3 will be input from the high-pressure steam inlet of the steam booster, expand and do work after entering the negative pressure chamber, and the exhaust steam in the fourth pipeline 9 will be extracted, injected and compressed through the injection fluid inlet. After they finally reach a consistent pressure and temperature, they will be discharged from the expansion port at the end of the venturi tube. Since the steam temperature output from the steam turbine intermediate pressure cylinder 3 is 400-450°C, after mixing with the exhaust steam, the exhaust steam temperature can be increased to about 200-260°C. Compared with the steam extracted from the steam turbine intermediate pressure cylinder 3 to heat the heating water for secondary heating, a large amount of exhaust steam can be used to replace the steam discharged from the steam turbine intermediate pressure cylinder 3 to heat the heat storage module 8, which not only improves the utilization efficiency of the exhaust steam, but also reduces the loss of high-quality steam heat source.

[0030] Furthermore, if Figure 1 As shown, the heat storage module 8 includes a primary heat exchange unit 81, a secondary heat exchange unit 82 and a tertiary heat exchange unit 83 which are connected in series in sequence, and the primary heat exchange unit 81, the secondary heat exchange unit 82 and the tertiary heat exchange unit 83 are respectively connected to the first pipeline 5, the fifth pipeline 11 and the third pipeline 7.

[0031] In the above embodiments, the heating water used to supply heat to the heating network users will pass through the primary heat exchange unit 81, the secondary heat exchange unit 82 and the tertiary heat exchange unit 83 in sequence, wherein the primary heat exchange unit 81 is connected to the exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine, and the heating water can be preheated by the exhaust steam from the low-pressure cylinder 4 of the steam turbine. The preheated heating water will reach the secondary heat exchange unit 82, and the secondary heat exchange unit 82 is connected to the fifth pipeline 11. The fifth pipeline 11 discharges a mixed gas of the steam discharged from the intermediate-pressure cylinder 3 of the steam turbine and the low-pressure cylinder 4 of the steam turbine, which can perform secondary heating on the heating water to further increase the heating water temperature. After the heating water is further heated by the secondary heat exchange unit 82, it will continue to pass through the tertiary heat exchange unit 83, wherein the tertiary heat exchange unit 83 uses the high-quality steam heat source from the high-pressure cylinder 2 of the steam turbine for the final heating, thereby controlling the temperature of the heating water to the ideal hot water temperature, so as to ensure that the heating water can provide sufficient heating temperature for each community when it reaches them. When providing heat energy for heating water, if only exhaust steam is used for heating, not only is the utilization rate of exhaust steam limited, but also the heating effect of exhaust steam as a low-quality heat source is unstable. If only the steam extracted from the intermediate pressure cylinder 3 or the high pressure cylinder 2 of the steam turbine is used to heat the heating water, not only will it consume more high-quality heat sources, but also because the temperature of these steams and the heating water to be heated is very high, it is not very convenient to regulate. This application adopts a step-by-step utilization of thermal energy, and uses them step by step and multiple times according to the quality of steam, so that energy can be fully and reasonably utilized in different stages and processes, thereby improving the overall utilization efficiency of steam thermal energy of the steam turbine and reducing energy waste.

[0032] Furthermore, if Figure 1 As shown, the primary heat exchange unit 81 is a pre-condenser, and the secondary heat exchange unit 82 is a steam booster condenser. The steam inlet of the pre-condenser is connected to the end of the first pipeline 5 away from the low-pressure cylinder 4 of the steam turbine, and the air inlet end of the steam booster condenser is connected to the end of the fifth pipeline 11 away from the steam booster; the water inlet end of the pre-condenser is connected to the return pipe of the heat network user, and the water outlet end of the pre-condenser is connected to the water inlet end of the steam booster condenser through a water pipe.

[0033] In the above embodiments, the structures of the pre-condenser and the steam booster condenser of the present application are the same as the condenser structure used in thermal power plants, and the working principle of the condenser is mainly based on cooling and compression. After the steam to be utilized enters the condenser, it exchanges heat with the cooling medium water, releases the latent heat of vaporization and becomes condensed water. The released latent heat is taken away by the cooling medium in the condenser. In this way, the steam is continuously condensed through the condenser, and the heat in the steam is continuously transferred to the cooling medium. The pre-condenser of the present application is mainly used to transfer the heat of a part of the exhaust steam in the low-pressure cylinder 4 of the turbine to the heating water for primary heating thereof. The booster condenser of the present application is mainly used to transfer the heat of the mixed steam obtained by mixing the steam extracted from the intermediate-pressure cylinder 3 of the turbine and another part of the exhaust steam discharged from the low-pressure cylinder 4 of the turbine to the heating water after primary heating to ensure that the temperature of the heating water is further increased rapidly. The pre-condenser and the booster condenser can condense the exhaust steam in the turbine into water, and at the same time establish and maintain a high vacuum of the corresponding turbine (when the exhaust steam of the turbine is cooled, the overall specific volume will shrink sharply, thus causing a higher vacuum at the exhaust port of the turbine, which can make the steam expand to the minimum pressure in the turbine, increase the available enthalpy drop of the steam in the turbine, and improve the cycle thermal efficiency), which can improve the cycle thermal efficiency when the turbine is working. The present application uses heating water as a cooling medium for heat exchange with steam. While meeting the above-mentioned requirements for steam discharge from the intermediate pressure cylinder 3 and the low pressure cylinder 4 of the turbine, the heat can also be fully utilized to meet the heating needs of the user, effectively improving the utilization efficiency of thermal energy.

[0034] Furthermore, if Figure 1 As shown, the three-stage heat exchange unit 83 is a heat network heater, the steam inlet of the heat network heater is connected to the end of the third pipe 7 away from the high-pressure cylinder 2 of the steam turbine, the water outlet end of the steam booster condenser is connected to the water inlet end of the heat network heater through a water pipe, and the water outlet end of the heat network heater delivers hot water to the heat network users through the water pipe.

[0035] In the above embodiments, the heat network heater of the present application is a key equipment commonly used in traditional thermal power plants, which is mainly composed of shells, tube sheets, heat exchange tubes and heads. The steam extracted from the high-pressure cylinder 2 of the steam turbine flows outside the heat exchange tube, and the heating water after secondary heating flows through the heat exchange tube. The heat in the steam extracted from the high-pressure cylinder 2 of the steam turbine can be transferred to the heating water through the tube wall of the heat exchange tube, thereby achieving the effect of further strengthening the heating of the heating water to ensure that the water delivered to the users of the heat network meets the needs of users. Among them, the heat network heater has the advantages of high temperature resistance and high heat transfer coefficient (when the heat source is high-temperature superheated steam, the heat transfer efficiency K≥5500). Since the water temperature of the heating water can basically reach about 80% of the heating demand temperature after the first two heatings, the extraction steam (extracted steam) in the high-pressure cylinder 2 of the steam turbine is used to finally control the temperature of the heating water to ensure that the heating water is stably delivered to the users of the heat network.

[0036] The pre-condenser, steam booster condenser and heat network heater of the present application will all produce condensate during operation. In actual production, the condensate can be collected in a water tank. Subsequently, the condensate can be transported to the boiler 1 through the condensate pump via the feed water heater, feed water pump, etc. as needed, or transported to some places in the power generation system that need cooling water through a water pump, which can achieve the beneficial effect of saving water resources.

[0037] Furthermore, if Figure 1 As shown, a heat network circulation pump 12 is installed on the pipeline between the steam booster condenser and the heat network heater.

[0038] In the above embodiments, the heating water needs to circulate continuously during the heating process, continuously delivering the heat provided by the thermal power plant to the heating network users. In this process, whether the heating water is flowing to the heating network users or returning from the heating network users to the thermal power plant, it needs sufficient kinetic energy to power its movement. The heating network circulation pump 12 arranged between the steam booster condenser and the heating network heater in the present application can take on the function of driving the heating water circulation to continuously transfer heat energy to meet the heating needs of the heating network users in winter.

[0039] Furthermore, if Figure 2 As shown, the first pipeline 5 is also connected to a sixth pipeline 13 through a tee at the upstream pipe section of the connection between the first pipeline 5 and the fourth pipeline 9, and the sixth pipeline 13 is connected to the steam inlet of the air-cooled condenser 14 at one end away from the first pipeline 5; a first solenoid valve 15 is installed on the first pipeline 5, and the first solenoid valve 15 is located on the first pipeline 5 on the pipe section between the connection point between the first pipeline 5 and the sixth pipeline 13 and the connection point between the first pipeline 5 and the fourth pipeline 9; a second solenoid valve 16 is installed on the sixth pipeline 13, a third solenoid valve 17 is installed on the second pipeline 6, and a fourth solenoid valve 18 is installed on the third pipeline 7.

[0040] In the above embodiments, the solenoid valve is an industrial device commonly used in pipeline systems, which can be used to adjust the direction, flow, speed and other parameters of the medium. The solenoid valve is an industrial device that uses electromagnetic control and is widely used in industrial control systems to adjust the direction, flow, speed and other parameters of the medium. The solenoid valve controls the opening and closing of the valve through the electromagnetic force generated by the electromagnetic coil, thereby achieving control of the fluid, which makes it convenient for enterprises to remotely control the flow of the medium in the pipeline.

[0041] The present application sets the first solenoid valve 15 on the first pipeline 5 on the pipe section between the connection point between the first pipeline 5 and the sixth pipeline 13 and the connection point between the first pipeline 5 and the fourth pipeline 9, and sets the second solenoid valve 16 on the sixth pipeline 13, so that the technicians of the thermal power plant can control the exhaust steam volume of the low-pressure cylinder 4 of the steam turbine to the steam booster and the pre-condenser through the first solenoid valve 15, and control the exhaust steam volume flowing to the air-cooled condenser 14 through the second solenoid valve 16. Compared with setting the first solenoid valve 15 or the second solenoid valve 16 upstream of the connection point between the first pipeline 5 and the sixth pipeline 13, the regulation of the exhaust steam flow rate will be more accurate and flexible. The present application also installs the third solenoid valve 17 and the fourth solenoid valve 18 on the second pipeline 6 and the third pipeline 7 respectively, so that when heating the heating water of the heating system, the technicians can adjust the exhaust volume of the intermediate-pressure cylinder 3 and the high-pressure cylinder 2 of the steam turbine in time according to the actual situation to reduce the unnecessary loss of high-quality heat source. For example, when the exhaust steam supply of the low-pressure cylinder 4 of the steam turbine is large enough, in order to pressurize and heat more exhaust steam in the steam booster, the steam extraction of the intermediate-pressure cylinder 3 of the steam turbine can be adaptively increased. At this time, the primary and secondary heating efficiencies of the heating water will be relatively high, and the temperature of the heating water after the secondary heating may be relatively high. In this case, the steam extraction supply of the high-pressure cylinder 2 of the steam turbine can be appropriately reduced. In addition, the heating demand of users is seasonal. Usually, only when the ambient temperature is low in winter, the users of the heating network will have a higher demand for heat. In other seasons, the heating system does not need to be operated. At this time, the technicians can completely close the first solenoid valve 15, the third solenoid valve 17 and the fourth solenoid valve 18, and open the second solenoid valve 16 to restore the generator set to normal state. The exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine directly flows to the air-cooled condenser 14 for condensation treatment, and the steam discharged from the intermediate-pressure cylinder 3 of the steam turbine and the high-pressure cylinder 2 of the steam turbine is continuously put into the power generation system to generate power.

[0042] Furthermore, if Figure 3 As shown, a molten salt heat storage system 19 is installed on the sixth pipeline 13 .

[0043] In the above embodiments, the core principle of the molten salt heat storage system 19 is to store thermal energy in a high-temperature molten salt solution for subsequent conversion into electricity or thermal energy. It has the characteristics of low theoretical cost, high operating temperature, and environmental friendliness. In actual production, if the temperature of the exhaust steam is not enough to heat the molten salt in the molten salt heat storage system 19, a heating module can be added to the molten salt heat storage system 19 to heat the exhaust steam (for example, the electricity generated by the power plant can be used to drive a heat pump or heater to heat the exhaust steam).

[0044] Furthermore, both the pre-condenser and the steam booster condenser are hybrid condensers.

[0045] In the above embodiments, in the hybrid condenser, the cooling water is in direct contact with the exhaust steam of the steam turbine, the steam is condensed into water under the action of the cooling water and mixed with the cooling water, and the non-condensed air is extracted by the vacuum pump. Compared with the surface condenser, the hybrid condenser has the advantages of simple structure and high heat exchange efficiency. Since the condensed water cannot be used as boiler 1 feed water after mixing with the unclean cooling water, it is rarely used directly in modern steam turbine units. However, in the present application, the steam exhausted from the low-pressure cylinder 4 and the intermediate-pressure cylinder 3 of the turbine is used to heat the heating water in the pre-condenser and the booster condenser. The heating water and the cooling water of the pre-condenser and the booster condenser, the exhaust steam from the low-pressure cylinder 4 and the intermediate-pressure cylinder 3 of the turbine and the condensate produced by the heat exchange with these heating water and the heating water can be directly used in the heating system with low requirements on water quality. Therefore, the problems existing in the use of the hybrid condenser in the traditional power plant do not exist in the system of the present application. In addition, the heating system will have water loss problems due to pipeline leakage, sewage discharge or water discharge from the user system, and the condensate produced by the exhaust steam from the low-pressure cylinder 4 and the intermediate-pressure cylinder 3 of the turbine in the present application can just replenish the water for the heating system.

[0046] The implementation principle of this embodiment is: when it is necessary to supply heat to the heating network users, the heating network circulation pump 12 in the heating system can be started to make the water flow in the heating system start to circulate, and the low-temperature water will first flow into the pre-condenser to achieve the effect of primary heating through heat exchange with part of the exhaust steam discharged from the low-pressure cylinder 4 of the steam turbine. The heating water after primary heating will continue to flow to the steam booster condenser. The steam flowing into the steam inlet end of the steam booster condenser is mixed steam obtained by mixing part of the exhaust steam with the steam discharged from the intermediate-pressure cylinder 3 of the steam turbine through the steam booster. The temperature of the mixed steam is higher than that of ordinary exhaust steam. In the steam booster condenser, the mixed steam can perform secondary heating on the heating water to further increase its temperature. The secondary heated heating water will continue to flow to the heating network heater. The heating network heater can use the steam introduced from the high-pressure cylinder 2 of the steam turbine to perform tertiary heating on the heating water to ensure that the temperature of the water finally flowing to the heating network users is maintained at a specific value. This application adopts a cascade utilization method of thermal energy, and utilizes them step by step and multiple times according to the quality of steam, so that energy can be fully and reasonably utilized in different stages and processes, thereby improving the overall utilization efficiency of turbine steam thermal energy and reducing energy waste.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A steam turbine multi-stage exhaust system, comprising a steam turbine high pressure cylinder (2), a steam turbine intermediate pressure cylinder (3) and a steam turbine low pressure cylinder (4) connected to a heating boiler (1), characterized in that: The steam outlet of the low-pressure cylinder (4) of the steam turbine, the steam extraction port of the intermediate-pressure cylinder (3) of the steam turbine and the steam extraction port of the high-pressure cylinder (2) of the steam turbine are respectively connected to a heat storage module (8) of the heating system through a first pipeline (5), a second pipeline (6) and a third pipeline (7); the heat storage module (8) is used to provide heat energy necessary for heating to heat network users in the heating system; the heat storage module (8) and the heating boiler (1) are also arranged inside the power plant.

2. The multi-stage exhaust system for a steam turbine according to claim 1, characterized in that: The first pipeline (5) is connected to a fourth pipeline (9) via a tee, a steam mixing device (10) is provided between the second pipeline (6) and the heat storage module (8), the fourth pipeline (9) and the second pipeline (6) are connected to the heat storage module (8) via the steam mixing device (10), and the steam mixing device (10) can pressurize and increase the temperature of the exhaust steam in the first pipeline (5) through the steam in the second pipeline (6).

3. The multi-stage exhaust system for a steam turbine according to claim 2, characterized in that: The steam mixing device (10) is a steam booster, the second pipe (6) is connected to the high-pressure steam inlet of the steam booster at one end away from the intermediate-pressure cylinder (3) of the steam turbine, the fourth pipe (9) is connected to the injection fluid inlet of the steam booster at one end away from the second pipe (6), and the mixed steam outlet of the steam booster is connected to the heat storage module (8) via a fifth pipe (11).

4. The multi-stage exhaust system for a steam turbine according to claim 3, characterized in that: The heat storage module (8) comprises a primary heat exchange unit (81), a secondary heat exchange unit (82) and a tertiary heat exchange unit (83) which are connected in series in sequence, and the primary heat exchange unit (81), the secondary heat exchange unit (82) and the tertiary heat exchange unit (83) are respectively connected to the first pipeline (5), the fifth pipeline (11) and the third pipeline (7).

5. The multi-stage exhaust system for a steam turbine according to claim 4, characterized in that: The primary heat exchange unit (81) is a pre-condenser, and the secondary heat exchange unit (82) is a steam booster condenser. The steam inlet of the pre-condenser is connected to the end of the first pipeline (5) away from the low-pressure cylinder (4) of the steam turbine, and the air inlet end of the steam booster condenser is connected to the end of the fifth pipeline (11) away from the steam booster; the water inlet end of the pre-condenser is connected to the return pipe of the heat network user, and the water outlet end of the pre-condenser is connected to the water inlet end of the steam booster condenser via a water pipe.

6. The multi-stage exhaust system for a steam turbine according to claim 5, characterized in that: The three-stage heat exchange unit (83) is a heat network heater, the steam inlet of the heat network heater is connected to the end of the third pipe (7) away from the high-pressure cylinder (2) of the steam turbine, the water outlet end of the steam booster condenser is connected to the water inlet end of the heat network heater through a water pipe, and the water outlet end of the heat network heater delivers hot water to heat network users through the water pipe.

7. The multi-stage exhaust system for a steam turbine according to claim 6, characterized in that: A heat network circulation pump (12) is installed on the pipeline between the steam booster condenser and the heat network heater.

8. The multi-stage exhaust system for a steam turbine according to any one of claims 3 to 7, characterized in that: A sixth pipeline (13) is externally connected to the first pipeline (5) at a pipe section upstream of the connection between the first pipeline (5) and the fourth pipeline (9) through a tee, and the sixth pipeline (13) is connected to a steam inlet of an air-cooled condenser (14) at one end away from the first pipeline (5); a first solenoid valve (15) is installed on the first pipeline (5), and the first solenoid valve (15) is located on the first pipeline (5) on a pipe section between a connection point between the first pipeline (5) and the sixth pipeline (13) and a connection point between the first pipeline (5) and the fourth pipeline (9); a second solenoid valve (16) is installed on the sixth pipeline (13), a third solenoid valve (17) is installed on the second pipeline (6), and a fourth solenoid valve (18) is installed on the third pipeline (7).

9. The multi-stage exhaust system for a steam turbine according to claim 8, characterized in that: A molten salt heat storage system (19) is installed on the sixth pipeline (13).

10. The multi-stage exhaust system for a steam turbine according to claims 5 to 7, characterized in that: The pre-condenser and the steam booster condenser are both hybrid condensers.

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