A heat supply system and method for turbine exhaust steam extraction pressure

Abstract

The application discloses a steam turbine exhaust steam extraction pressure heat supply system and method, wherein the system structure comprises a primary heat supply network heater, a heat supply network circulating water inlet pipe is connected with a primary heat supply network circulating water supply pipe through the primary heat supply network heater; an exhaust steam extraction pipe is led out from a condenser, the exhaust steam extraction pipe is connected with a heating steam input end of the primary heat supply network heater, and a steam compressor is arranged on the exhaust steam extraction pipe; the system further comprises a secondary heat supply network heater, a secondary heating inlet pipe is led out from the primary heat supply network circulating water supply pipe, and the secondary heating inlet pipe is connected with a secondary heat supply network circulating water supply pipe through the secondary heat supply network heater; a heat supply steam extraction pipe is led out from a medium and low pressure cylinder communication pipe, and the heat supply steam extraction pipe is connected with a heating steam input end of the secondary heat supply network heater. The scheme realizes flexible high-back-pressure heat supply and heat supply network water cascade heating, is generally adaptable to heat supply network circulating water inlet temperature, is convenient to transform and flexible to operate, and improves heat economy of a unit.

Description

Technical Field

[0001] This invention belongs to the field of heating technology, specifically relating to a heating system and method for pressurizing exhaust steam from a steam turbine. Background Technology

[0002] With urbanization, the demand for centralized heating is constantly increasing. Cogeneration (combined heat and power) of coal-fired power units for centralized heating has always been an energy utilization method encouraged by the state. To meet the ever-growing heating demand, either new cogeneration units must be built, or existing condensing units around towns and cities must be retrofitted for heating purposes. Considering factors such as construction period, infrastructure investment, and the inherent need for existing coal-fired power units to transition to integrated energy systems, retrofitting condensing units for heating has become the preferred solution for meeting the needs of centralized heating in urban areas.

[0003] Currently, the following two schemes are generally adopted for converting pure condensing units into heating units.

[0004] Option 1, conventional renovation plan: such as Figure 2 As shown, a butterfly valve is installed on the connecting pipe of the low-pressure cylinder of the steam turbine, and the heating steam is drawn out from before the butterfly valve; a primary heating network heater is set up to directly heat the circulating water of the heating network to the rated temperature for external supply, generally 130℃. Scheme 1 is simple and easy to implement, but there is a loss of steam extraction work capacity.

[0005] Option 2, traditional high back pressure tiered heating system: such as Figure 3 As shown, the traditional high back-pressure heating scheme (the condenser acts as the primary heat network heater, and the heat network water return water replaces the circulating cooling water, which is first heated to a certain intermediate temperature, such as 60℃) + butterfly valves are installed on the connecting pipes of the medium and low pressure cylinders. The heating steam is drawn out before the butterfly valves (a secondary heat network heater is set up, and the heat network water at the condenser outlet is introduced into the inlet of the secondary heat network heater to further heat the heat network circulating water to the rated temperature for external supply, generally 130℃). Scheme 2 is constrained by the heat network circulating water return water temperature and back pressure. If the back pressure increases significantly, the flow path of the low-pressure cylinder needs to be modified, which is not only costly and time-consuming, but also requires the pure condensing rotor to be replaced during the non-heating season, making the operation inflexible. If the traditional high back-pressure heating scheme is adopted and the rotor is not modified, there are strict requirements for condensate temperature, unit back pressure, heat network circulating water inlet temperature, and outlet temperature, which narrows the applicable range. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a heating system and method for boosting the exhaust steam of a steam turbine, which solves the problems of existing solutions such as loss of steam extraction capacity for heating or high cost and narrow applicability. By reconfiguring the system, high back pressure stepped heating is achieved, which is universally adaptable to the temperature of the circulating water in the heating network and does not involve any modification to the steam turbine itself. It is not only convenient to modify and flexible to operate, but also reduces the loss of steam extraction capacity for heating and improves the thermal economy of the unit.

[0007] According to the first aspect of the present invention, the present invention provides a heating system for boosting the pressure of exhaust steam from a steam turbine, including a primary heating network heater, wherein the inlet pipe of the heating network circulating water is connected to the primary heating network circulating water supply pipe through the primary heating network heater; a condenser is connected to the low-pressure cylinder of the steam turbine, and an exhaust steam extraction pipe is led out from the condenser and connected to the heating steam input end of the primary heating network heater, wherein a steam compressor is installed on the exhaust steam extraction pipe; the system also includes a secondary heating network heater, wherein a secondary heating inlet pipe is led out from the primary heating network circulating water supply pipe and connected to the secondary heating network circulating water supply pipe through the secondary heating network heater; an intermediate-low pressure cylinder connecting pipe is connected between the intermediate-low pressure cylinder and the low-pressure cylinder of the steam turbine, and a heating extraction steam pipe is led out from the intermediate-low pressure cylinder connecting pipe and connected to the heating steam input end of the secondary heating network heater.

[0008] In some embodiments, a heating butterfly valve is installed on the medium- and low-pressure cylinder connecting pipe, and the connection point between the heating extraction pipe and the medium- and low-pressure cylinder connecting pipe is located upstream of the heating butterfly valve.

[0009] In some implementations, a heating extraction steam pipe is equipped with an electric regulating valve for heating extraction steam; a heating network circulating water inlet pipe is equipped with a heating network circulating water inlet valve and a heating network circulating water pump; a primary heating network circulating water supply valve is installed downstream of the connection point between the primary heating network circulating water supply pipe and the secondary heating water inlet pipe; a secondary heating water inlet valve is installed on the secondary heating water inlet pipe; and a secondary heating network circulating water supply valve is installed on the secondary heating network circulating water supply pipe.

[0010] In some embodiments, the drain outlet of the primary heating network heater is connected to the hot well of the condenser via a primary heating drain cooling pipe, and a primary drain cooler is provided on the primary heating drain cooling pipe.

[0011] In some implementations, the drain outlet of the secondary heating network heater is connected to the hot well of the condenser via a secondary heating drain cooling pipe, and a secondary drain cooler is provided on the secondary heating drain cooling pipe.

[0012] In some embodiments, a heat exchange tube bundle is provided in the condenser, the heat exchange tube bundle is located above the hot well, and the input end of the exhaust steam extraction pipe is located above the heat exchange tube bundle; the heat exchange tube bundle is connected to the cooling tower through a circulating cooling water pipe.

[0013] According to the second aspect of the present invention, the present invention provides a heating method for turbine exhaust steam pressurization, which employs the turbine exhaust steam pressurization heating system of the present invention, and includes the following components: Based on the heating load requirements, either a primary heating network heater supply scheme or a primary and secondary heating network heater series operation scheme is adopted. The primary heating network heater supply scheme is that the circulating water of the heating network is heated to the required first temperature by the primary heating network heater and then directly used as the water supply output. When the required water supply temperature exceeds the design temperature range that the primary heating network heater can achieve, a series operation scheme of the primary and secondary heating network heaters shall be adopted. The series operation scheme of the primary and secondary heating network heaters is as follows: after the circulating water of the heating network is heated by the primary heating network heater, it continues to enter the secondary heating network heater and is heated to the required water supply temperature before being used as the water supply output.

[0014] In some implementations, the first temperature is 100°C ± 10°C.

[0015] In some implementations, the steam compressor pressure ratio is 14 to 28.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention, based on the concept of tiered heating, breaks through the limitations of traditional high back-pressure heating technology on the temperature of the heating network circulating water. It proposes using a steam compressor to increase the pressure of the turbine exhaust steam, with the pressurized steam serving as the primary heat source for heating the circulating water. The heated circulating water can be directly supplied to the outside according to heating load requirements, or it can be sent to a secondary heating network heater for further heating to the rated temperature before being supplied to the outside. This solution achieves flexible high back-pressure heating and tiered heating of the heating network water, has broad adaptability to the inlet water temperature of the heating network, does not involve modifications to the turbine's flow path, and is not only convenient to modify and flexible in operation, but also reduces the energy loss of the extracted steam for heating, improving the unit's thermal economy. This solution is an innovative approach to converting a pure condensing unit into a heating unit, with strong technical and economic feasibility, and is worthy of development and promotion. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the heating system for boosting exhaust steam from a steam turbine provided by the present invention.

[0018] Figure 2 This is a structural schematic diagram of the heating system of the existing technical solution 1.

[0019] Figure 3 This is a schematic diagram of the heating system of the existing technical solution 2.

[0020] Explanation of reference numerals in the attached figures: 1. Primary heating network heater; 2. Heating network circulating water inlet pipe; 3. Primary heating network circulating water supply pipe; 4. Low-pressure cylinder; 5. Condenser; 6. Exhaust steam extraction pipe; 7. Steam compressor; 8. Secondary heating network heater; 9. Secondary heating inlet pipe; 10. Secondary heating network circulating water supply pipe; 11. Intermediate-pressure cylinder; 12. Intermediate-low pressure cylinder connecting pipe; 13. Heating extraction steam pipe; 14. Heating butterfly valve; 15. Heating network circulating water inlet valve; 16. Heating network circulating water pump; 17. Primary heating network circulating water supply valve; 18. Secondary heating inlet valve; 19. Secondary heating network circulating water supply valve; 20. Secondary heating condensate cooling pipe; 21. Secondary condensate cooler; 22. Heat exchanger tube bundle; 23. Cooling tower; 24. Heating extraction steam electric regulating valve; 25. Primary heating condensate cooling pipe; 26. Primary condensate cooler. Detailed Implementation

[0021] This invention provides a heating system and method for boosting turbine exhaust steam pressure. Specifically, it is a heating system structure and method for boosting turbine exhaust steam pressure to improve unit thermal efficiency and reduce retrofit costs. It solves the problems of large loss of heating extraction steam for work capacity, high cost, and narrow applicability in existing solutions. Through system reconstruction, it achieves high back pressure stepped heating, has broad adaptability to the inlet water temperature of the heating network, and does not involve modification of the turbine's flow path. It is not only convenient to retrofit and flexible to operate, but also reduces the loss of heating extraction steam for work capacity and improves the unit's thermal economy.

[0022] Please refer to the following first. Figure 2 In the existing technology, Scheme 1 is simple and easy to implement, but it sacrifices the work capacity of the extracted steam for heating. The low-pressure cylinder pressure in a pure condensing unit is generally around 1 MPa, while the cylinder pressure required to meet the rated heating network outlet water temperature is around 0.4 MPa. Therefore, there is a loss of extracted steam work capacity, especially at the beginning and end of the heating season when the required heating water temperature is relatively low, resulting in a greater loss of extracted steam work capacity.

[0023] Because conventional retrofit schemes involve a loss of steam extraction capacity for heating, even if the cylinder pressure is 0.4 MPa.a to meet the rated heating network outlet water temperature, the required extraction steam pressure is generally 0.1 MPa.a at the beginning and end of the heating season when the required heating water temperature is relatively low. The loss of steam extraction capacity for heating at 0.4 MPa.a is still significant.

[0024] To address the aforementioned issues, the engineering approach proposes a tiered heating scheme for the heating network, combining traditional high back-pressure heating with extraction steam heating (such as...). Figure 3 Scheme 2 shown).

[0025] Because the exhaust steam temperature of the turbine is limited by factors such as the expansion and deformation of the exhaust cylinder structure, bearing vibration, and the safety of the last-stage blades, the low-pressure cylinder exhaust steam temperature has requirements, generally not exceeding 80℃, corresponding to a turbine exhaust pressure of approximately 47 kPa·s. Assuming the return water from the heating network is used as the cooling water for the unit's condenser, the following constraints apply: 1) The return water temperature of the heating network should not exceed 60℃ (considering heat exchange temperature rise, heat exchange terminal temperature difference and turbine safety). 2) The back pressure rise is controlled within a reasonable range so that the turbine flow path does not require major modifications.

[0026] Take a traditional high back pressure heating project as an example.

[0027] The rated back pressure of the condenser in the pure condensing unit is 5 kPa.a, and the return water temperature of the heating network is 53℃. The steam entering the condenser is heated to 78℃ by the unit's exhaust steam before being connected to the heating network heaters, increasing the condenser back pressure to 45 kPa. Due to this significant increase in back pressure, the enthalpy drop of the last few stages of the unit's blades decreases, the steam dynamic characteristics deteriorate, the exhaust temperature of the low-pressure cylinder rises sharply, the volumetric flow rate of the last stage decreases, and the dynamic stress increases sharply, jeopardizing operational safety. A specially designed rotor is required. The length of the last stage blades on the new rotor is reduced from the original 1029 mm to 350 mm. The last stage diaphragm and moving blades are eliminated, and a guide ring is installed at the last stage diaphragm location to ensure smooth steam passages and reduce interstage steam flow losses. During the non-heating season, when the exhaust back pressure returns to normal levels, the unit needs to be reinstalled with the original pure condensing rotor.

[0028] The above analysis shows that if the back pressure increases significantly, the low-pressure cylinder needs to be modified. This not only results in high costs and a long construction period, but also requires the replacement with a pure condensing rotor during the non-heating season, making operation inflexible.

[0029] If a traditional high back-pressure heating scheme is adopted, with no rotor modification, safe unit operation, and safe operation of condensate polishing (requiring condensate temperature generally not to exceed 65℃), based on engineering experience, the back pressure of air-cooled units should not exceed 25 kPa·a (the appropriate inlet water temperature for the heating network circulation should not exceed 50℃, and the outlet water temperature should not exceed 60℃), and the back pressure of wet-cooled units should not exceed 15 kPa·a (the appropriate inlet water temperature for the heating network circulation should not exceed 40℃, and the outlet water temperature should not exceed 50℃). The return water temperature of the heating network circulation is generally 70℃, and heating network systems with a return water temperature below 50℃ are rare. Therefore, the traditional high back-pressure heating scheme is limited by the return water temperature of the heating network circulation, resulting in a narrow range of applicability.

[0030] In summary, a new heating system retrofit scheme for pure condensing units is needed to overcome the shortcomings of the existing technologies.

[0031] Please see Figure 1This invention discloses a steam turbine exhaust steam pressurization heating system, comprising a primary heating network heater 1, and a heating network circulating water inlet pipe 2 connected to a primary heating network circulating water supply pipe 3 via the primary heating network heater 1. A condenser 5 is connected to the low-pressure cylinder 4 of the steam turbine, and an exhaust steam extraction pipe 6 is led out from the condenser 5. The exhaust steam extraction pipe 6 is connected to the heating steam input end of the primary heating network heater 1, and a steam compressor 7 is installed on the exhaust steam extraction pipe 6.

[0032] This scheme uses a steam compressor to increase the turbine exhaust pressure, and the pressurized steam serves as the steam source for the primary heater of the heating network circulating water system. The rated back pressure of a wet-cooled unit is generally 5 kPa·a, while that of an air-cooled unit is generally 10 kPa·a. The steam compressor extracts the unit exhaust steam from the condenser. Considering that the primary heating of the heating network water is mainly suitable for the initial and final stages of heating, the outlet water temperature is generally controlled at around 100℃, while also ensuring the compressor pressure ratio is within a reasonable range. Considering the reasonable heat exchange end difference of the heating network heaters, the steam-side saturation temperature of the primary heating network heater is taken as 110℃ (considering a 10℃ end difference), corresponding to an extraction steam pressure of approximately 140 kPa·a. The compressor pressure ratio is between 14 (air-cooled unit) and 28 (wet-cooled unit), which is suitable, and the steam compressor selection is appropriate. Currently, there are centrifugal and axial-flow steam compressor types. Centrifugal compressors are suitable for high pressure ratios and low flow rates, while axial-flow compressors are suitable for medium to low pressure ratios and high flow rates. There are one or more steam compressors. The number of steam compressors operating in parallel is determined based on the heating steam extraction volume required by the heat load and the output of a single unit.

[0033] It also includes a secondary heating network heater 8. A secondary heating water supply pipe 9 is led out from the primary heating network circulating water supply pipe 3, and the secondary heating water supply pipe 9 is connected to the secondary heating network circulating water supply pipe 10 through the secondary heating network heater 8. An intermediate-low pressure cylinder connecting pipe 12 is connected between the intermediate-pressure cylinder 11 and the low-pressure cylinder 4 of the steam turbine. A heating extraction steam pipe 13 is led out from the intermediate-low pressure cylinder connecting pipe 12, and the heating extraction steam pipe 13 is connected to the heating steam input end of the secondary heating network heater 8.

[0034] This scheme incorporates a two-stage heating network heater, with steam sourced from the connecting pipe between the medium and low-pressure cylinders (more specifically, upstream of the newly added heating butterfly valve on the connecting pipe between the medium and low-pressure cylinders). During the initial and final stages of the heating season, the heating network water outlet from the primary heating network heater generally meets the heating requirements and is supplied directly. If the heating network needs further temperature increases, the heated primary heating network water is then fed into the secondary heating network heater to be heated to the rated temperature before being supplied externally. In other words, it allows for either primary heating network heater supply or a primary + secondary heating network heater series operation scheme, depending on the heating load requirements.

[0035] Overall, the primary heating network heater utilizes boosted exhaust steam for heating, reducing the amount of steam extracted for heating in the secondary heating network heater, minimizing the energy loss from the extracted steam for work, and improving the unit's thermal economy. Furthermore, the primary heating network heater's use of boosted exhaust steam eliminates limitations on the inlet water temperature of the heating network; the temperature can be adjusted by changing the steam compressor pressure ratio, resulting in a system with broad applicability and flexible operation. In addition, this scheme does not involve modifications to the turbine's flow path, making modifications convenient and cost-effective.

[0036] More specifically, the system of this invention also includes necessary pumps, valves, etc., to control the flow direction and flow rate of steam and water, and can be designed according to requirements. Specifically, for example... Figure 1 In the illustrated embodiment, a heating butterfly valve 14 is installed on the medium-low pressure cylinder connecting pipe 12, and the connection point between the heating extraction steam pipe 13 and the medium-low pressure cylinder connecting pipe 12 is located upstream of the heating butterfly valve 14. A heating extraction steam electric regulating valve 24 is installed on the heating extraction steam pipe 13. A heating network circulating water inlet valve 15 and a heating network circulating water pump 16 are installed on the heating network circulating water inlet pipe 2. A primary heating network circulating water supply valve 17 is installed downstream of the connection point with the secondary heating inlet water pipe 9 on the primary heating network circulating water supply pipe 3. A secondary heating inlet water valve 18 is installed on the secondary heating inlet water pipe 9. A secondary heating network circulating water supply valve 19 is installed on the secondary heating network circulating water supply pipe 10.

[0037] Considering the relatively high condensate temperature of the secondary heat network heater 8 (e.g., about 140°C), it is designed to be cooled by the secondary condensate cooler 21 before being sent to the condenser hot well. Specifically, the condensate output end of the secondary heat network heater 8 is connected to the hot well of the condenser 5 through the secondary heating condensate cooling pipe 20, and the secondary heating condensate cooling pipe 20 is equipped with the secondary condensate cooler 21.

[0038] Similarly, the condensate outlet of the primary heating network heater 1 is connected to the hot well of the condenser 5 through the primary heating condensate cooling pipe 25, and a primary condensate cooler 26 is provided on the primary heating condensate cooling pipe 25.

[0039] The condenser 5 is equipped with a heat exchange tube bundle 22, located above the heat well. The inlet end of the exhaust steam extraction pipe 6 is also located above the heat exchange tube bundle 22. The heat exchange tube bundle 22 is connected to the cooling tower 23 via a circulating cooling water pipe. The circulating cooling water pipe is equipped with the necessary circulating cooling water inlet valve, circulating cooling water return valve, and circulating cooling water pump. During operation, the condenser circulating water operates normally, maintaining the back pressure of the condenser 5 at the rated value.

[0040] Based on the turbine exhaust steam pressurization heating system described above, this invention provides a turbine exhaust steam pressurization heating method, which includes the following: The heating scheme can be either a primary heating network heater or a primary and secondary heating network heater connected in series, depending on the heating load requirements.

[0041] The primary heating network heater supply scheme is as follows: the circulating water of the heating network is heated to the required first temperature by the primary heating network heater 1 and then directly output as the water supply; the secondary heating network heater 8 does not work.

[0042] When the required water supply temperature exceeds the design temperature range that the primary heating network heater can achieve, a series operation scheme of primary and secondary heating network heaters shall be adopted.

[0043] The series operation scheme of the primary and secondary heating network heaters is as follows: after the circulating water of the heating network is heated by the primary heating network heater 1, it continues to enter the secondary heating network heater 8 and is heated to the required water supply temperature before being used as the water supply output.

[0044] The first temperature is, for example, 100℃ ± 10℃. The pressure ratio of the steam compressor 7 is, for example, 14 to 28. The secondary heating network heater 8 heats the water to the required supply temperature, for example, 130℃ ± 10℃.

[0045] In summary, this invention, based on the concept of tiered heating, breaks through the limitations of traditional high back-pressure heating technology on the temperature of the heating network circulating water. It proposes using a steam compressor to increase the pressure of the turbine exhaust steam, with the pressurized steam serving as the primary heat source for heating the network circulating water. The heated network circulating water can be directly supplied to the outside according to heating load requirements, or it can be sent to a secondary heating network heater for further heating to the rated temperature before being supplied to the outside. This solution achieves flexible high back-pressure heating and tiered heating of the heating network water, has broad adaptability to the incoming water temperature of the heating network, does not involve modifications to the turbine's flow path, and is not only convenient to modify and flexible in operation, but also reduces the energy loss of the extracted steam for heating, improving the unit's thermal economy. This solution is an innovative approach to converting a pure condensing unit into a heating unit, with strong technical and economic feasibility, and is worthy of development and promotion.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; obviously, the described embodiments are some embodiments of the present invention, but not all embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention; in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions for some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heating system for boosting the pressure of exhaust steam from a steam turbine, characterized in that, The system includes a primary heating network heater (1), a heating network circulating water inlet pipe (2) which is connected to the primary heating network circulating water supply pipe (3) through the primary heating network heater (1); a condenser (5) is connected to the low-pressure cylinder (4) of the steam turbine, and a waste steam extraction pipe (6) is drawn out from the condenser (5). The waste steam extraction pipe (6) is connected to the heating steam input end of the primary heating network heater (1), and a steam compressor (7) is installed on the waste steam extraction pipe (6). It also includes a secondary heating network heater (8), a secondary heating water pipe (9) is led out from the primary heating network circulating water supply pipe (3), and the secondary heating water pipe (9) is connected to the secondary heating network circulating water supply pipe (10) through the secondary heating network heater (8); a medium-low pressure cylinder connecting pipe (12) is connected between the intermediate pressure cylinder (11) and the low pressure cylinder (4) of the steam turbine, and a heating extraction pipe (13) is led out from the medium-low pressure cylinder connecting pipe (12), and the heating extraction pipe (13) is connected to the heating steam input end of the secondary heating network heater (8).

2. The steam turbine exhaust steam pressurization heating system according to claim 1, characterized in that, A heating butterfly valve (14) is installed on the medium and low pressure cylinder connecting pipe (12), and the connection point between the heating extraction pipe (13) and the medium and low pressure cylinder connecting pipe (12) is located on the upstream side of the heating butterfly valve (14).

3. The steam turbine exhaust steam pressurization heating system according to claim 1, characterized in that, A heating steam extraction pipe (13) is equipped with a heating steam extraction electric regulating valve (24); a heating network circulating water inlet pipe (2) is equipped with a heating network circulating water inlet valve (15) and a heating network circulating water pump (16); a primary heating network circulating water supply pipe (3) is equipped with a primary heating network circulating water supply valve (17) on the downstream side of the connection point with the secondary heating inlet pipe (9); a secondary heating inlet pipe (9) is equipped with a secondary heating inlet valve (18); a secondary heating network circulating water supply pipe (10) is equipped with a secondary heating network circulating water supply valve (19).

4. The steam turbine exhaust steam pressurization heating system according to claim 1, characterized in that, The drain outlet of the primary heating network heater (1) is connected to the hot well of the condenser (5) through the primary heating drain cooling pipe (25), and a primary drain cooler (26) is provided on the primary heating drain cooling pipe (25).

5. The steam turbine exhaust steam pressurization heating system according to claim 1, characterized in that, The drain outlet of the secondary heat network heater (8) is connected to the hot well of the condenser (5) through the secondary heating drain cooling pipe (20), and a secondary drain cooler (21) is provided on the secondary heating drain cooling pipe (20).

6. The heating system for boosting turbine exhaust steam according to any one of claims 1 to 4, characterized in that, A heat exchange tube bundle (22) is installed in the condenser (5). The heat exchange tube bundle (22) is located above the hot well, and the input end of the exhaust steam extraction pipe (6) is located above the heat exchange tube bundle (22). The heat exchange tube bundle (22) is connected to the cooling tower (23) through the circulating cooling water pipe.

7. A method for heating by pressurizing exhaust steam from a steam turbine, characterized in that, It employs a steam turbine exhaust steam pressurization heating system according to any one of claims 1 to 6, which includes the following: Based on the heating load requirements, either a primary heating network heater supply scheme or a primary and secondary heating network heater series operation scheme is adopted. The primary heating network heater heating scheme is that the circulating water of the heating network is heated to the required first temperature by the primary heating network heater (1) and then directly used as the water supply output; When the required water supply temperature exceeds the design temperature range that the primary heating network heater can achieve, a series operation scheme of the primary and secondary heating network heaters shall be adopted. The series operation scheme of the primary and secondary heating network heaters is as follows: after the heating network circulating water is heated by the primary heating network heater (1), it continues to enter the secondary heating network heater (8) and is heated to the required water supply temperature before being used as water supply output.

8. The method for heating by pressurizing turbine exhaust steam according to claim 7, characterized in that, The first temperature is 100℃±10℃.

9. The method for heating by pressurizing turbine exhaust steam according to claim 7, characterized in that, The pressure ratio of the steam compressor (7) is 14 to 28.

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