High-temperature return water step-by-step flash steam supply and waste heat utilization system

Abstract

The present application provides a high-temperature return water step-by-step flash steam supply and waste heat utilization system, which relates to the field of energy recovery and utilization technology. The system includes: a pressure regulating device, which is used to use high-temperature and high-pressure return water to generate power and produce the first return water after decompression; a first-level vaporization device, which is used to decompress and evaporate the first return water of the heat exchange device, and produce the second return water after secondary decompression; a second-level vaporization device, which is used to decompress and evaporate the first return water of the heat exchange device, and produce the third return water after secondary decompression; a second-level vaporization device, which is used to decompress and evaporate the second return water of the heat exchange device, and produce the third return water after secondary decompression; a heat exchange device, which is used to heat the condensate generated by the steam turbine unit by using the combined second return water and the third return water, and transport the return water after heat exchange to the decondensate well of the steam turbine unit for recycling. The system of the present application can effectively utilize the waste heat of high-temperature and high-pressure return water.

Description

Technical Field

[0001] The present application relates to the technical field of energy recovery and utilization, and in particular to a high-temperature return water step-by-step flash evaporation steam supply and waste heat utilization system. Background Art

[0002] High-temperature and high-pressure industrial steam is widely used in the fields of chemical industry, petroleum, textile, printing and dyeing, papermaking, food, restaurant, hospital, school, power and energy. Usually, the temperature of high-temperature condensed return water produced after indirect heating can still reach above 200℃. After leaving the heat-using equipment, the high-temperature condensed return water still contains about 25% of the heat of steam, which is a considerable waste heat resource. If it is directly discharged into the natural environment, it will not only cause a large amount of energy waste, but also cause thermal pollution to the surrounding environment. However, there is currently no structure that can effectively utilize the waste heat of return water. Utility Model Content

[0003] The purpose of the embodiments of the present application is to provide a high-temperature return water step-by-step flash steam supply and waste heat utilization system to solve the above-mentioned problems.

[0004] In order to achieve the above-mentioned purpose, the present application provides a high-temperature return water step-by-step flash steam supply and waste heat utilization system, comprising:

[0005] A pressure regulating device is used to utilize high-temperature and high-pressure return water to generate power and produce the first return water after pressure reduction;

[0006] A first stage vaporizing device connected to the pressure regulating device, used for reducing the pressure and evaporating the first return water to produce second return water after secondary pressure reduction;

[0007] A second primary vaporizing device connected to the pressure regulating device, used to reduce the pressure and evaporate the first return water to produce third return water after secondary pressure reduction;

[0008] A secondary vaporization device connected to the first primary vaporization device, used to reduce the pressure and evaporate the second return water to produce third return water after secondary pressure reduction;

[0009] The heat exchange device is used to heat the condensate produced by the steam turbine unit by using the combined second return water and the third return water, and transport the return water after heat exchange to the decondensate well of the steam turbine unit for recycling.

[0010] Optionally, the first stage vaporization device is further used to generate first steam with a first pressure;

[0011] The second stage vaporization device is also used to generate second steam with a second pressure;

[0012] The secondary vaporization device is further used to generate third steam having the second pressure.

[0013] Optionally, the system further comprises:

[0014] a temperature and pressure reduction device connected to the first-stage vaporization device, used for reducing the pressure of the second steam to generate fourth steam with a third pressure, and delivering the fourth steam to the first heating user;

[0015] The first-stage vaporization device is also used to transport the first steam to a second heating user, the second-stage vaporization device is also used to transport the second steam to a third heating user, and the second-stage vaporization device is also used to transport the third steam to the third heating user.

[0016] Optionally, the first pressure is greater than the second pressure, the third pressure is greater than the second pressure, and the third pressure is less than the first pressure.

[0017] Optionally, the pressure regulating device is a hydraulic turbine device.

[0018] Optionally, the first-stage vaporization device, the second-stage vaporization device and the second-stage vaporization device are all flash tanks.

[0019] Optionally, the drainage end of the pressure regulating device is connected to the water inlet end of the first-stage vaporization device and the water inlet end of the second-stage vaporization device respectively, and the drainage end of the first-stage vaporization device is connected to the water inlet end of the second-stage vaporization device;

[0020] The drainage end of the second-stage vaporization device is connected to the drainage end of the second-stage vaporization device and then connected to the water inlet end of the heat exchange device;

[0021] The water discharge end of the heat exchange device is connected to the water inlet end of the decondensate well of the steam turbine unit.

[0022] Optionally, the exhaust end of the first-stage vaporization device is connected to the steam inlet end of the temperature reduction and pressure reduction device, the temperature reduction and pressure reduction device delivers the fourth steam to the first heating user through its exhaust end, and the first-stage vaporization device delivers the first steam to the second heating user through its exhaust end;

[0023] The exhaust end of the second-stage vaporization device is connected to the exhaust end of the second-stage vaporization device to transport the second steam and the third steam to the third heating user.

[0024] Optionally, the heat exchange device comprises:

[0025] Heat exchangers and multi-stage low-pressure heaters;

[0026] The low-temperature medium input end of the heat exchanger is connected to the water inlet end of the multi-stage low-pressure heater, and the water discharge end of the multi-stage low-pressure heater is connected to the low-temperature medium output end of the heat exchanger;

[0027] The drainage end of the second-stage vaporization device is connected to the drainage end of the second-stage vaporization device and then connected to the high-temperature medium input end of the heat exchanger, and the high-temperature medium output end of the heat exchanger is connected to the water inlet end of the decondensate well of the steam turbine unit;

[0028] The steam inlet end of the multi-stage low-pressure heater is connected to the exhaust end of the steam turbine unit.

[0029] Optionally, the multi-stage low-pressure heater comprises:

[0030] a first low-pressure heater, a second low-pressure heater, a third low-pressure heater, and a fourth low-pressure heater;

[0031] The output end of the first low-pressure heater is connected to the low-temperature medium output end of the heat exchanger, the input end of the first low-pressure heater is connected to the output end of the second low-pressure heater, the input end of the second low-pressure heater is connected to the output end of the third low-pressure heater, the input end of the third low-pressure heater is connected to the output end of the fourth low-pressure heater, and the input end of the fourth low-pressure heater is connected to the low-temperature medium input end of the heat exchanger and then connected to the drainage end of the water supply pump.

[0032] The embodiments provided in this application have the following beneficial effects:

[0033] The system of the present application can generate power by reducing the pressure of high-temperature and high-pressure return water through a hydraulic turbine, and then flash-evaporating the return water step by step to produce multi-stage low-pressure steam. This can supply steam to users with different needs based on the scenario where there are steam users in chemical parks around thermal power companies. At the same time, the flash condensate can be sent back to the power plant, and the waste heat can be used to heat the condensate system. Finally, the remaining return water is directly recycled by entering the condensate well of the power plant turbine after water treatment, thereby effectively utilizing the waste heat of the high-temperature and high-pressure return water.

[0034] Other features and advantages of the embodiments or implementations of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0036] Figure 1 The system structure diagram of the high-temperature return water step-by-step flash steam supply and waste heat utilization system of the embodiment of the present application is schematically shown.

[0037] Description of Reference Numerals

[0038] 1-pressure regulating device, 2-first stage vaporizing device, 3-second stage vaporizing device, 4-second stage vaporizing device, 5-temperature reduction and pressure reduction device, 6-heat exchanger, 7-first low-pressure heater, 8-second low-pressure heater, 9-third low-pressure heater, 10-fourth low-pressure heater. DETAILED DESCRIPTION

[0039] The specific implementation of the embodiment of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present application, and is not used to limit the embodiment of the present application.

[0040] In order to solve the above problems, Figure 1 As shown, the first aspect of the present application provides a high-temperature return water step-by-step flash steam supply and waste heat utilization system, comprising:

[0041] A pressure regulating device 1 is used to utilize high-temperature and high-pressure return water to generate power and produce first return water after pressure reduction; a first-stage vaporization device 2 connected to the pressure regulating device 1 is used to reduce the pressure and evaporate the first return water to produce second return water after secondary pressure reduction; a second-stage vaporization device 3 connected to the pressure regulating device 1 is used to reduce the pressure and evaporate the first return water to produce third return water after secondary pressure reduction; a second-stage vaporization device 4 connected to the first-stage vaporization device 2 is used to reduce the pressure and evaporate the second return water to produce third return water after secondary pressure reduction; a heat exchange device is used to utilize the combined second return water and third return water to heat the condensate generated by the steam turbine unit, and transport the return water after heat exchange to the decondensate well of the steam turbine unit for recycling.

[0042] In this way, the system of the present application can generate multi-stage low-pressure steam by stepping down the high-temperature and high-pressure return water through a hydraulic turbine to generate electricity, and then flash-evaporating the return water step by step. It can supply steam to users with different needs based on the scenario where there are steam users in chemical parks around thermal power companies. At the same time, the flash condensate can be sent back to the power plant, and the waste heat can be used to heat the condensate system. Finally, the remaining return water can be directly recycled by entering the condensate well of the power plant turbine after water treatment.

[0043] It can be understood that in this application, the high-temperature and high-pressure return water can be the high-temperature and high-pressure return water generated at the end of the process after the thermal power plant supplies the high-temperature and high-pressure steam to the surrounding chemical enterprises in demand. For example, taking the comprehensive utilization of high-temperature return water of a chemical park enterprise as an example, the high-temperature and high-pressure return water parameters are 600t / h, 12Mpa, 285°C. In this application, the pressure regulating device 1 is a hydraulic turbine device, and the first-stage vaporization device 2, the second-stage vaporization device 3 and the second-stage vaporization device 4 are all flash tanks. The working principle of the hydraulic turbine device is to make the high-pressure medium liquid flow through the impellers of each stage of the hydraulic turbine, reduce the pressure step by step, and convert the pressure energy into mechanical energy through the impeller to rotate the hydraulic turbine rotor. Therefore, the application reduces the pressure of the high-temperature and high-pressure return water to about 7MPa above the saturation pressure through the hydraulic turbine device, and generates a differential pressure power generation power of about 722kW, and sends the generated electricity to the power system of the power plant. At the same time, the high-temperature water (600t / h, ≥6.92Mpa, 285℃) after the pressure reduction by the hydraulic turbine device is respectively sent to the two primary flash tanks of line A (355t / h) and line B (245t / h), that is, the first primary gasification device and the second primary vaporization device 3, wherein the pressure levels of the first primary gasification device and the second primary vaporization device 3 are different. The high-temperature return water from the hydraulic turbine device is depressurized and flashed in the two primary flash tanks to cool the high-temperature return water and generate steam. Among them, the flash tank is mainly used in the liquid separation process. Its working principle is based on the different boiling points of substances. By reducing the pressure, the volatile components in the liquid evaporate rapidly, thereby achieving the separation of different components in the mixture. This will not be elaborated here.

[0044] Specifically, the first stage vaporization device 2 is also used to generate a first steam with a first pressure; the second stage vaporization device 3 is also used to generate a second steam with a second pressure; and the second stage vaporization device 4 is also used to generate a third steam with a second pressure. The first pressure is 2.79 MPa, and the second pressure is 0.79 MPa, that is, the first stage vaporization device 2 and the second stage vaporization device 3 generate saturated steam (53 t / h) of 2.79 MPa and saturated steam (65 t / h) of 0.79 MPa, respectively.

[0045] In the present application, in order to supply steam to users with different needs through the waste heat of high-temperature return water, the system of the present application also includes: a temperature and pressure reduction device connected to the first-level vaporization device 2, which is used to reduce the pressure of the second steam to generate a fourth steam with a third pressure, and transport the fourth steam to the first heating user. The first-level vaporization device 2 is also used to transport the first steam to the second heating user, the second-level vaporization device 3 is also used to transport the second steam to the third heating user, and the second-level vaporization device 4 is also used to transport the third steam to the third heating user, wherein the first pressure is greater than the second pressure, the third pressure is greater than the second pressure, and the third pressure is less than the first pressure. In the present application, the third pressure is 1.3MPa. Among them, the exhaust end of the first-level vaporizer 2 is connected to the steam inlet end of the temperature reduction and pressure reduction device, and the temperature reduction and pressure reduction device transmits the fourth steam to the first heating user through its exhaust end, and the first-level vaporizer 2 transmits the first steam to the second heating user through its exhaust end; the exhaust end of the second-level vaporizer 3 is connected to the exhaust end of the second-level vaporizer 4 to transmit the second steam and the third steam to the third heating user. Specifically, the 2.79MPa saturated steam (53t / h) from the first-level vaporizer 2 provides 2t / h, 1.3MPa(g) saturated steam to the first user of the park after pipeline loss and temperature reduction and pressure reduction device, and the 2.79MPa saturated steam (53t / h) from the first-level vaporizer 2 provides 51t / h, 2.5MPa(g) saturated steam to the second user of the park after pipeline loss. The high-temperature saturated water (about 2.8MPa, 230℃, 302t / h) generated by the first-stage flash tank of Line A is sent to the second-stage flash tank to reduce the pressure to 0.79MPa for flash evaporation, generating 40t / h, 0.79MPa saturated steam, i.e. the third steam, which is combined with 65t / h, 0.79MPa saturated steam, i.e. the second steam, generated by the first-stage flash tank of Line B. After pipeline loss, 0.6MPa(g) saturated steam is provided to the third user of the park. Among them, the small gap in the demand for saturated steam can be supplemented by the park itself or by steam extraction from the power plant.

[0046] In the present application, the drainage end of the pressure regulating device 1 is connected to the water inlet end of the first-stage vaporization device 2 and the water inlet end of the second-stage vaporization device 3 respectively, and the drainage end of the first-stage vaporization device 2 is connected to the water inlet end of the second-stage vaporization device 4; the drainage end of the second-stage vaporization device 3 is connected to the drainage end of the second-stage vaporization device 4 and then connected to the water inlet end of the heat exchange device, and the saturated water (442t / h, 170℃) coming out of the second-stage flash tank of line A and the first-stage flash tank of line B are combined to heat the low-pressure part of the condensate of the power plant; the drainage end of the heat exchange device is connected to the water inlet end of the de-condensate well of the turbine unit.

[0047] In the present application, the heat exchange device includes: a heat exchanger 6 and a multi-stage low-pressure heater; the low-temperature medium input end of the heat exchanger 6 is connected to the water inlet end of the multi-stage low-pressure heater, and the drainage end of the multi-stage low-pressure heater is connected to the low-temperature medium output end of the heat exchanger 6; the drainage end of the second-stage vaporization device 3 is connected to the drainage end of the second-stage vaporization device 4 and then connected to the high-temperature medium input end of the heat exchanger 6, and the high-temperature medium output end of the heat exchanger 6 is connected to the water inlet end of the decondensation well of the steam turbine unit; the steam inlet end of the multi-stage low-pressure heater is connected to the exhaust end of the steam turbine unit. It can be understood that the steam turbine low-pressure heater is one of the heat exchange equipment of the steam turbine, and its function is to heat the discharged condensed water in the low-pressure section of the steam turbine and send the heated steam back to the steam turbine, thereby improving the efficiency of the steam turbine, which will not be repeated here.

[0048] Among them, a first solenoid valve can also be arranged between the drainage end of the second-stage vaporization device 3 and the high-temperature medium input end of the heat exchanger 6, and a second solenoid valve can also be arranged between the drainage end of the second-stage vaporization device 4 and the high-temperature medium input end of the heat exchanger 6. In this way, the return water flow entering the heat exchanger can be controlled by controlling the on-off of the solenoid valve. At the same time, when a fault occurs, the connection between the flash tank and the heat exchanger can be cut off by the solenoid valve, which is beneficial to the maintenance and detection of the system.

[0049] Specifically, the multi-stage low-pressure heater of the present application includes: a first low-pressure heater 7, a second low-pressure heater 8, a third low-pressure heater 9 and a fourth low-pressure heater 10; the output end of the first low-pressure heater 7 is connected to the low-temperature medium output end of the heat exchanger 6, the input end of the first low-pressure heater 7 is connected to the output end of the second low-pressure heater 8, the input end of the second low-pressure heater 8 is connected to the output end of the third low-pressure heater 9, the input end of the third low-pressure heater 9 is connected to the output end of the fourth low-pressure heater 10, and the input end of the fourth low-pressure heater 10 is connected to the low-temperature medium input end of the heat exchanger 6 and then connected to the discharge end of the feed water pump. Specifically, the steam inlet ends of the first low-pressure heater 7, the second low-pressure heater 8, the third low-pressure heater 9 and the fourth low-pressure heater 10 are respectively connected to the 5#~8# extraction steam of the steam turbine. The saturated water (442t / h, 170℃) from the secondary flash tank of line A and the primary flash tank of line B is used for waste heat utilization. After the temperature is reduced (about 41±5℃), it is directly sent to the condensate well of the power plant turbine for recycling after water treatment. Among them, the waste heat utilization of the saturated water (442t / h, 170℃) from the secondary flash tank of line A and the primary flash tank of line B can reduce the steam extraction of turbines 5#~8#, and the reduced steam extraction can be used for low-pressure cylinder power generation, which can increase the power generation by about 5840kW.

[0050] In summary, the waste heat utilization heat source of this application is the high-temperature return water after the chemical enterprise uses high-temperature and high-pressure steam to heat the equipment. It is a low-quality heat source with a certain temperature and pressure. In addition, since the water quality of the generated steam condensate is good, this application further recycles it. Since the high-temperature and high-pressure return water usually has a high pressure (>10MPa, >200℃), this application first generates electricity (to 5~7MPa) through a hydraulic turbine depressurization (without cooling), and then recovers the waste heat, and the generated electricity is incorporated into the power system of the power plant. At the same time, the high-temperature return water after the hydraulic turbine is depressurized is further depressurized and flashed to generate steam to supply steam users with lower pressure. According to the different steam pressures of the users, one or more flash evaporations are set to obtain the required saturated steam. The condensed water after flash evaporation is sent back to the power plant to heat the condensate system using waste heat. The return water after waste heat utilization (about 41±5℃) is directly recycled into the condensate well of the power plant turbine after water treatment.

[0051] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0052] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A high-temperature return water step-by-step flash steam supply and waste heat utilization system, characterized in that: include: A pressure regulating device is used to utilize high-temperature and high-pressure return water to generate power and produce the first return water after pressure reduction; A first stage vaporizing device connected to the pressure regulating device, used for reducing the pressure and evaporating the first return water to produce second return water after secondary pressure reduction; A second primary vaporizing device connected to the pressure regulating device, used to reduce the pressure and evaporate the first return water to produce third return water after secondary pressure reduction; A secondary vaporization device connected to the first primary vaporization device, used to reduce the pressure and evaporate the second return water to produce third return water after secondary pressure reduction; The heat exchange device is used to heat the condensate produced by the steam turbine unit by using the combined second return water and the third return water, and transport the return water after heat exchange to the decondensate well of the steam turbine unit for recycling.

2. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 1 is characterized in that: The first stage vaporization device is also used to generate first steam with a first pressure; The second stage vaporization device is also used to generate second steam with a second pressure; The secondary vaporization device is further used to generate third steam having the second pressure.

3. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 2 is characterized in that: The system further comprises: a temperature and pressure reduction device connected to the first-stage vaporization device, used for reducing the pressure of the second steam to generate fourth steam with a third pressure, and delivering the fourth steam to the first heating user; The first-stage vaporization device is also used to transport the first steam to a second heating user, the second-stage vaporization device is also used to transport the second steam to a third heating user, and the second-stage vaporization device is also used to transport the third steam to the third heating user.

4. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 3 is characterized in that: The first pressure is greater than the second pressure, the third pressure is greater than the second pressure, and the third pressure is less than the first pressure.

5. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 3 is characterized in that: The pressure regulating device is a hydraulic turbine device.

6. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 3 is characterized in that: The first-stage vaporization device, the second-stage vaporization device and the second-stage vaporization device are all flash tanks.

7. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 3 is characterized in that: The drainage end of the pressure regulating device is connected to the water inlet end of the first-stage vaporization device and the water inlet end of the second-stage vaporization device respectively, and the drainage end of the first-stage vaporization device is connected to the water inlet end of the second-stage vaporization device; The drainage end of the second-stage vaporization device is connected to the drainage end of the second-stage vaporization device and then connected to the water inlet end of the heat exchange device; The water discharge end of the heat exchange device is connected to the water inlet end of the decondensate well of the steam turbine unit.

8. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 7 is characterized in that: The exhaust end of the first-stage vaporization device is connected to the steam inlet end of the temperature reduction and pressure reduction device, the temperature reduction and pressure reduction device delivers the fourth steam to the first heating user through its exhaust end, and the first-stage vaporization device delivers the first steam to the second heating user through its exhaust end; The exhaust end of the second-stage vaporization device is connected to the exhaust end of the second-stage vaporization device to transport the second steam and the third steam to the third heating user.

9. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 7, characterized in that: The heat exchange device comprises: Heat exchangers and multi-stage low-pressure heaters; The low-temperature medium input end of the heat exchanger is connected to the water inlet end of the multi-stage low-pressure heater, and the water discharge end of the multi-stage low-pressure heater is connected to the low-temperature medium output end of the heat exchanger; The drainage end of the second-stage vaporization device is connected to the drainage end of the second-stage vaporization device and then connected to the high-temperature medium input end of the heat exchanger, and the high-temperature medium output end of the heat exchanger is connected to the water inlet end of the decondensate well of the steam turbine unit; The steam inlet end of the multi-stage low-pressure heater is connected to the exhaust end of the steam turbine unit.

10. The high-temperature return water step-by-step flash steam supply and waste heat utilization system according to claim 9, characterized in that: The multi-stage low-pressure heater comprises: a first low-pressure heater, a second low-pressure heater, a third low-pressure heater, and a fourth low-pressure heater; The output end of the first low-pressure heater is connected to the low-temperature medium output end of the heat exchanger, the input end of the first low-pressure heater is connected to the output end of the second low-pressure heater, the input end of the second low-pressure heater is connected to the output end of the third low-pressure heater, the input end of the third low-pressure heater is connected to the output end of the fourth low-pressure heater, and the input end of the fourth low-pressure heater is connected to the low-temperature medium input end of the heat exchanger and then connected to the drainage end of the water supply pump.

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