A steam turbine exhaust steam comprehensive utilization device capable of maintaining controllable pressure difference

Abstract

The utility model discloses a kind of turbine exhaust comprehensive utilization devices of maintaining controllable pressure difference, including steam turbine, condenser, air ejector, circulating water pump and condensate pump, the steam outlet of steam turbine is communicated with the steam side entrance of external negative pressure difference type waste heat recovery device by a steam extraction pipe fitting, and the water side import and export of negative pressure difference type waste heat recovery device is connected with heat user side system.This utility model relates to the technical field of energy saving of thermal system, the turbine exhaust comprehensive utilization device of maintaining controllable pressure difference, by setting additional exhaust steam waste heat utilization pipeline and the heat exchanger of waste heat utilization at the exhaust steam outlet of steam turbine, and by controlling heat exchanger outlet flow and pipeline inlet flow and the flow of main pipeline are corrected, to ensure that back pressure is not too high, steam turbine normal operation is not affected.

Description

Technical Field

[0001] This utility model relates to the field of energy-saving technology for thermal systems, specifically to a steam turbine exhaust steam comprehensive utilization device that maintains controllable pressure difference. Background Technology

[0002] Condensing steam turbine exhaust contains a large amount of low-grade heat energy, which is currently mainly dissipated into the environment through air-cooled islands or circulating cooling water systems, resulting in significant energy waste and water evaporation losses. Simultaneously, power plants need to consume low-pressure steam to preheat the raw water in the water treatment workshop to prevent scaling of the reverse osmosis membrane and improve water production rate during the water treatment process. Furthermore, low-pressure steam is required for heating in winter, leading to high operating costs. Condensing units, especially air-cooled units, commonly experience problems in summer where high ambient temperatures cause increased back pressure in the turbine's low-pressure cylinder, reduced unit efficiency, and even forced load reduction operation.

[0003] In existing technologies, although there have been attempts to recover this part of the waste heat, they all have limitations: if heat exchange devices are installed in the turbine building, space is limited; and if steam is drawn from the condenser to the outside, if the design is not proper, the back pressure of the turbine's low-pressure cylinder exhaust pipe will be increased due to the increase in system resistance. Although some of the latent heat of the exhaust steam can be recovered, it will inevitably increase the back pressure of the turbine's low-pressure cylinder exhaust pipe, reducing the power generation efficiency.

[0004] Traditional, simple heat exchange solutions cannot resolve the conflict between induced draft steam back pressure and control precision, nor can they assist in reducing the back pressure of the turbine's low-pressure cylinder exhaust pipe during summer. Therefore, there is an urgent need for a comprehensive solution that can absolutely guarantee that the back pressure of the turbine's low-pressure cylinder exhaust pipe does not rise, accommodate multiple heat demands, and achieve precise and intelligent control. Utility Model Content

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a comprehensive steam turbine exhaust gas utilization device that maintains controllable pressure differential, solving the problem of increased exhaust gas back pressure during the utilization of steam turbine waste heat.

[0006] (II) Technical Solution To achieve the above objectives, this utility model provides the following technical solution: a steam turbine exhaust steam comprehensive utilization device for maintaining controllable differential pressure, comprising a steam turbine, a condenser, an extractor, a circulating water pump and a condensate pump, wherein the exhaust port of the steam turbine is connected to the steam side inlet of an external negative differential pressure waste heat recovery unit through a steam extraction pipe, and the water side inlet and outlet of the negative differential pressure waste heat recovery unit are connected to the heat user side system.

[0007] The steam-side outlet of the negative pressure differential waste heat recovery unit is connected to the condenser via a condensate recovery pump.

[0008] A vacuum maintenance component is connected to the exhaust port of the negative pressure differential waste heat recovery unit to control the pressure difference between the negative pressure differential waste heat recovery unit and the condenser.

[0009] The heat user-side system includes a PLC controller that outputs control signals to the vacuum maintaining component to dynamically adjust the aforementioned differential pressure value.

[0010] As a further preferred embodiment, the vacuum maintenance assembly includes a vacuum pump unit, a gas-water separator, a heat exchanger, and a pressure transmitter, wherein a pressure sensor is installed on the pipeline between the vacuum pump unit and the negative pressure differential waste heat recovery unit to detect the gas pressure in the pipeline on that side.

[0011] As a further preferred embodiment, the vacuum pump assembly includes at least two water ring vacuum pumps, with at least one of the water ring vacuum pumps in standby mode.

[0012] As a further preferred embodiment, the steam extraction pipe is equipped with a pressure sensor for real-time detection of the throat pressure of the condenser.

[0013] As a further preferred embodiment, the negative pressure differential waste heat recovery unit is provided with a water-side regulating valve at the water-side inlet and a temperature sensor at its water-side outlet.

[0014] As a further preferred embodiment, the steam extraction pipe is provided with a pneumatic isolation valve and a steam-side regulating valve in sequence along the steam flow direction.

[0015] As a further preferred embodiment, the steam extraction fitting includes a steam pipe with an inlet that is a flared, gradually expanding port.

[0016] (III) Beneficial Effects This invention provides a steam turbine exhaust steam comprehensive utilization device for maintaining controllable differential pressure. It has the following beneficial effects: 1. The turbine exhaust gas comprehensive utilization device with controllable differential pressure is designed to ensure that the back pressure is not too high and will not affect the normal operation of the turbine by setting an additional exhaust gas waste heat utilization pipeline and a waste heat utilization heat exchanger at the exhaust gas outlet of the turbine, and by controlling the outlet flow of the heat exchanger, the inlet flow of the pipeline, and the flow of the main pipeline.

[0017] 2. This solution also innovatively adopts a cascade control strategy for steam outlet pressure and water outlet temperature, achieving high-precision regulation of steam flow and water outlet temperature. This system can be safely used for heating raw water or for heating purposes, and can automatically enhance condensation efficiency and assist in reducing the main unit back pressure under high back pressure conditions in the low-pressure cylinder of the steam turbine during summer, achieving safe, precise, multifunctional, and highly reliable automated recovery of low-grade exhaust heat. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the structure of this utility model; Figure 2 This is a block diagram of the cascade temperature control of this utility model; Figure 3 This is a block diagram of the negative pressure differential closed-loop control of this utility model.

[0019] In the diagram: 1. Steam turbine; 2. Condenser; 3. Ejector; 4. Circulating water pump; 5. Condensate pump; 6. Negative pressure differential waste heat recovery unit; 7. Steam extraction pipe fittings; 8. Condensate recovery pump; 9. Pressure sensor; 10. Steam-side regulating valve; 11. Pressure sensor one; 12. Vacuum pump set; 13. Gas-water separator; 14. Heat exchanger; 15. PLC controller; 16. Temperature sensor; 17. Water-side regulating valve; 18. Pneumatic isolation valve. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1-3 As shown, this utility model provides a technical solution: a steam turbine exhaust steam comprehensive utilization device for maintaining controllable pressure difference, including a steam turbine 1, a condenser 2, an air extractor 3, a circulating water pump 4, and a condensate pump 5.

[0022] It should be noted that, Figure 1 The equipment described in the dashed section is all located outside the factory building.

[0023] The exhaust port of the steam turbine 1 is connected to the steam side inlet of the external negative pressure differential waste heat recovery unit 6 (a low-resistance shell-and-tube heat exchanger located outside the plant) through a steam intake pipe 7. The steam intake pipe 7 includes a steam pipe with a flared, gradually expanding inlet.

[0024] It should be noted that the pipe diameter is designed for a steam flow rate of ≤50m / s. The nominal diameter of the pipe is not less than DN800. Its inlet is equipped with a flared gradually expanding interface. The entire pipe is insulated and equipped with a drainage point. Large radius elbows (R≥3D) are used to minimize flow resistance.

[0025] A pressure sensor 9 is installed on the steam extraction pipe 7 to detect the throat pressure of the condenser 2 in real time. The water side inlet and outlet of the negative pressure differential waste heat recovery unit 6 are connected to the heat user side system.

[0026] A pneumatic isolation valve 18 and a steam-side regulating valve 10 are sequentially installed on the steam intake pipe 7 along the steam flow direction.

[0027] The negative pressure differential waste heat recovery unit 6 is equipped with a water-side regulating valve 17 (preferably an equal percentage characteristic regulating valve for regulating flow) at the water-side inlet and a temperature sensor 16 at the water-side outlet for detecting the outlet water temperature.

[0028] The steam-side outlet of the negative pressure differential waste heat recovery unit 6 is connected to the condenser 2 via the condensate recovery pump 8.

[0029] A vacuum maintaining component is connected to the exhaust port of the negative pressure differential waste heat recovery unit 6 to control the pressure difference between the negative pressure differential waste heat recovery unit 6 and the condenser 2.

[0030] Specifically, the vacuum maintenance assembly includes a vacuum pump unit 12 (preferably a frequency-controlled Roots-water ring vacuum unit), a gas-water separator 13, a heat exchanger 14, and a pressure transmitter. A pressure sensor 11 is installed on the pipeline between the vacuum pump unit 12 and the negative pressure differential waste heat recovery unit 6 to detect the gas pressure in the pipeline.

[0031] The working fluid of the water ring vacuum pump is turbine condensate. During normal operation, the water pressurized by the condensate recovery pump 8 maintains the normal water level inside the vacuum pump through the makeup and drain float valves. As the working fluid generates heat by performing work within the pump body and absorbs heat from the gas extracted from the condenser 2, its temperature rises. To maintain the working fluid temperature below its vaporization temperature and prevent pump cavitation, the working fluid reciprocating within the system needs to be continuously cooled. The steam-gas mixture drawn from the condenser 2 enters the vacuum pump through an isolation valve. The gas compressed and discharged by the vacuum pump enters the gas-water separator 13, and the separated gas enters the atmosphere through an exhaust valve.

[0032] When the working fluid carrying gas is discharged into the gas-water separator 13, under the combined action of a certain positive pressure in the separator and a certain negative pressure in the vacuum pump body, the working fluid flows out of the gas-water separator 13, is cooled by a heat exchanger 14 installed on one side of the pump body, and is directly replenished into the pump body as working fluid. After doing work in the pump body, it is discharged into the gas-water separator 13.

[0033] Externally supplied water is added to the vacuum pump through a water level regulating valve, and this cycle repeats continuously. The reason for choosing the water ring vacuum pump as the pumping equipment is that, under the same suction pressure, the time required for the water ring vacuum pump to establish a vacuum during startup is much shorter than that of other pumping equipment, and the continuous operation economy of the water ring vacuum pump is significantly better than that of other pumping equipment.

[0034] Furthermore, the vacuum pump unit 12 includes at least two water ring vacuum pumps, with at least one of them in standby mode. This one-in-use, one-in-standby configuration ensures continuous operation and reliability of the system and effectively controls the rise in back pressure of the turbine's low-pressure cylinder.

[0035] The heat user-side system includes a PLC controller 15, which outputs control signals to the vacuum maintaining component to dynamically adjust the aforementioned differential pressure value.

[0036] The PLC controller 15 is the core of the system control. It has built-in CPU module, input / output (I / O) module, PID controller and differential pressure controller and other functional modules. The controller stores preset safe differential pressure setpoint and outlet water temperature setpoint.

[0037] Its control logic is divided into two parts: Part 1 (Safety Interlock): Pressure sensor 9 and pressure sensor 112 respectively monitor the throat pressure P1 of condenser 2 and the steam-side outlet pressure P2 of the negative pressure differential waste heat recovery unit 6. The differential pressure controller automatically calculates its negative pressure differential value ΔP and compares it with the safe differential pressure setpoint, through a single-loop feedback control system (see...). Figure 3 Adjust the frequency value of the inverter of the vacuum pump group 12 to precisely control the pumping volume of the vacuum pump group 12 and maintain a constant negative pressure difference.

[0038] If the negative pressure difference of the negative pressure differential waste heat recovery unit 6 is insufficient (i.e., ΔP ≥ 0), the safety interlock system immediately closes the pneumatic isolation valve 18, and the system immediately shuts down, waiting for the resumption signal, without affecting the operation of the main unit. Simultaneously, the PLC controller 15 monitors the back pressure of the turbine's low-pressure cylinder exhaust pipe. If it exceeds the summer warning value, it automatically optimizes the safety negative pressure differential setpoint to a larger value, and the cascade control system quickly adjusts the opening of the steam-side regulating valve 10 to improve the condensing capacity of the negative pressure differential waste heat recovery unit 6, thus assisting in reducing the main unit's back pressure.

[0039] Part Two (Real-time Cascade Control System): Please refer to... Figure 2 Temperature sensor 16 detects the outlet water temperature of the negative pressure differential waste heat recovery unit 6. Cascade control system: The secondary controller (i.e., the steam-side pressure controller) controls the opening of the steam-side regulating valve 10 based on the water temperature control parameters output by the main controller (i.e., the outlet water temperature controller), the pressure measurement value from pressure sensor 11, and the turbine back pressure parameters, quickly stabilizing the steam-side operating conditions. The outer loop feeds back the temperature measurement feedback value from the outlet water temperature sensor 16 to the main controller, which outputs parameters to the secondary controller. This allows the secondary controller to adjust the opening of the steam-side regulating valve 10, achieving precise water temperature control. The water-side regulating valve 17 provides auxiliary fine-tuning.

[0040] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0041] In use, a steam extraction pipe 7 and a negative pressure differential waste heat recovery device 6 for waste heat utilization are connected separately to the exhaust steam outlet of the original steam turbine 1. The pressure sensor 9 on the steam extraction pipe 7 detects the gas pressure P1 on the pipeline.

[0042] Meanwhile, a vacuum pump unit 12 is installed at the air extraction port of the negative pressure differential waste heat recovery unit 6, and the air pressure P2 on the pipeline is detected by the pressure sensor 11 on the pipeline.

[0043] The differential pressure controller receives P1 and P2, calculates the real-time differential pressure ΔP, automatically calculates its negative differential pressure value ΔP (ΔP=P1-P2) through the PID controller, compares it with the safe differential pressure setpoint, and outputs a control signal to the vacuum pump group 12. This is achieved through a single-loop feedback control system (see...). Figure 3 Adjust the frequency value of the inverter of the vacuum pump group 12 to precisely control the pumping volume of the vacuum pump group 12 and maintain a constant negative pressure difference.

[0044] If the negative pressure difference of the negative pressure differential waste heat recovery unit 6 is insufficient (i.e., ΔP ≥ 0), the safety interlock system will immediately close the pneumatic isolation valve 18, and the system will immediately stop and wait for the resumption signal. This will not affect the operation of the main unit.

[0045] Meanwhile, the PLC controller 15 monitors the back pressure of the exhaust pipe of the low-pressure cylinder of the steam turbine 1. If it exceeds the summer warning value, it will automatically optimize the safe negative pressure difference setting value to a larger value, and the cascade control system will quickly adjust the opening of the steam-side regulating valve 10 to improve the condensation capacity of the negative pressure difference waste heat recovery unit 6 and help reduce the back pressure of the main unit.

[0046] Furthermore, such as Figure 2 As shown, the steam-side outlet pressure value P2 of the negative pressure differential waste heat recovery unit 6 is used as the inner loop controlled secondary variable (secondary object), and the water-side outlet temperature value of the negative pressure differential waste heat recovery unit 6 is used as the outer loop controlled primary variable (primary object). The secondary controller (i.e., the steam-side pressure controller) controls the opening of the steam-side regulating valve 10 based on the water temperature control parameters output by the primary controller (i.e., the outlet water temperature controller), the pressure measurement value of the pressure sensor 11, and the turbine back pressure parameters, thereby quickly stabilizing the steam-side operating conditions. The outer loop feeds back the temperature measurement feedback value from the outlet water temperature sensor 16 to the primary controller, and the primary controller outputs parameters to the secondary controller, thereby achieving precise control of the water temperature by adjusting the opening of the steam-side regulating valve 10 through the secondary controller.

[0047] It should be noted that all electrical components mentioned in this article are connected to an external main controller and 380V AC mains power. The main controller can be a conventional, known device such as a computer, and its control principles, internal structure, and control switching methods are all conventional methods in existing technology. These are directly cited here without further elaboration. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A steam turbine exhaust steam comprehensive utilization device for maintaining controllable differential pressure, comprising a steam turbine (1), a condenser (2), an extractor (3), a circulating water pump (4), and a condensate pump (5), characterized in that: The exhaust port of the steam turbine (1) is connected to the steam side inlet of the external negative pressure differential waste heat recovery unit (6) through a steam intake pipe (7), and the water side inlet and outlet of the negative pressure differential waste heat recovery unit (6) are connected to the heat user side system. The steam-side outlet of the negative pressure differential waste heat recovery unit (6) is connected to the condenser (2) via the condensate recovery pump (8); A vacuum maintaining component is connected to the exhaust port of the negative pressure differential waste heat recovery unit (6) to control the pressure difference between the negative pressure differential waste heat recovery unit (6) and the condenser (2); The heat user-side system includes a PLC controller (15) that outputs control signals to the vacuum maintaining component to dynamically adjust the differential pressure value.

2. The turbine exhaust steam comprehensive utilization device for maintaining controllable pressure difference according to claim 1, characterized in that: The vacuum maintenance assembly includes a vacuum pump group (12), a gas-water separator (13), a heat exchanger (14), and a pressure transmitter. A pressure sensor (11) is installed on the pipeline between the vacuum pump group (12) and the negative pressure differential waste heat recovery unit (6) to detect the gas pressure in the pipeline.

3. The turbine exhaust steam comprehensive utilization device for maintaining controllable pressure difference according to claim 2, characterized in that: The vacuum pump assembly (12) includes at least two water ring vacuum pumps, and at least one of the water ring vacuum pumps is in standby mode.

4. The turbine exhaust steam comprehensive utilization device for maintaining controllable pressure difference according to claim 1, characterized in that: A pressure sensor (9) is installed on the steam extraction pipe (7) to detect the throat pressure of the condenser (2) in real time.

5. The turbine exhaust steam comprehensive utilization device for maintaining controllable differential pressure as described in claim 1, characterized in that: The negative pressure differential waste heat recovery unit (6) is equipped with a water-side regulating valve (17) at the water-side inlet and a temperature sensor (16) at its water-side outlet.

6. The turbine exhaust steam comprehensive utilization device for maintaining controllable pressure difference according to claim 4, characterized in that: A pneumatic isolation valve (18) and a steam-side regulating valve (10) are sequentially arranged along the steam flow direction on the steam extraction pipe (7).

7. A turbine exhaust steam comprehensive utilization device for maintaining controllable differential pressure as described in claim 6, characterized in that: The steam extraction fitting (7) includes a steam pipe with an inlet that is a flared, gradually expanding port.

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