A peak shaving gas turbine unit shaft seal cooler heat source recovery system

Abstract

A kind of shaft seal cooler heat source recovery system of peak shaving gas unit, including heat source introduction pipeline, plate heat exchanger and heating return water main pipeline, heat source introduction pipeline is used to guide heat source to the hot side entrance of plate heat exchanger, heating return water main pipeline is connected with the cold side entrance of plate heat exchanger;Parallel connection has bypass pipeline between the cold side entrance and the cold side outlet of plate heat exchanger;It further includes temperature regulating device arranged in the downstream of the cold side outlet pipeline of plate heat exchanger, the inlet end of temperature regulating device is simultaneously connected the outlet of cold side outlet pipeline of plate heat exchanger and bypass pipeline;The outlet of temperature regulating device transports mixed temperature-controlled water to heating user pipe network, reaches the purpose of using waste heat to meet the heating demand of factory area, reduces external energy consumption.

Description

Technical Field

[0001] This invention relates to a heat source recovery system for a shaft seal cooler of a peak-shaving gas turbine unit, belonging to the technical field of gas turbine units. Background Technology

[0002] Many gas-fired power plants in my country are responsible for peak shaving of the power grid and do not participate in external heating or steam supply. In the winter in northern China, these types of power plants need to activate small-scale heating and heat exchange systems within the plant to provide heating for the office and production areas. This production method increases the plant's natural gas consumption, thereby increasing fuel costs. Technical personnel need to carefully analyze the peak-shaving power plant's production process, find ways to utilize energy in a cascade manner, reduce production costs, and further improve energy efficiency.

[0003] Chinese patent CN204554984U discloses a heating heat exchange device with flash steam waste heat recovery. It recovers condensate from the heating system through a condensate recovery device, generates flash steam within this device using pressure drop, and then recovers the heat of this flash steam using a plate heat exchanger to heat the water supply, thus achieving the recovery and utilization of condensate and its waste heat. However, the flash heat exchange mode used in this device is relatively basic. The flash process is completed in a single condensate recovery device, and the generated flash steam is directly introduced into the plate heat exchanger for indirect heat exchange. This simple structure results in high requirements for the stability of the flash steam quality (dryness, pressure). When the temperature, pressure, or flow rate of the heat source (such as condensate) fluctuates, the flash steam output and parameters are easily unstable, thus affecting the heat exchange efficiency of the plate heat exchanger and the stability of system operation, making it difficult to adapt to complex and variable industrial application scenarios. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides a heat source recovery system for the shaft seal cooler of a peak-shaving gas turbine unit, which achieves stable and efficient recovery and utilization of intermittent, drastically fluctuating, low-grade industrial waste heat.

[0005] The technical solution of the present invention is as follows: A heat source recovery system for a shaft seal cooler of a peak-shaving gas turbine unit includes a heat source inlet pipe, a plate heat exchanger, and a heating return water main pipe. The heat source inlet pipe guides the heat source to the hot-side inlet of the plate heat exchanger, and the heating return water main pipe is connected to the cold-side inlet of the plate heat exchanger. A bypass pipe is connected in parallel between the cold-side inlet and the cold-side outlet of the plate heat exchanger. The system also includes a temperature regulating device located downstream of the cold-side outlet pipe of the plate heat exchanger. The inlet of the temperature regulating device is connected to both the cold-side outlet pipe of the plate heat exchanger and the outlet of the bypass pipe. The outlet of the temperature regulating device delivers the mixed and temperature-regulated water to the heating user's pipe network.

[0006] The system includes a first valve on the heat source inlet pipeline for controlling the on / off state of return steam; a second valve on the bypass pipeline for controlling the on / off state; a check valve at the cold-side outlet pipeline of the plate heat exchanger; a temperature regulating device comprising a three-way regulating valve and a temperature sensor, wherein the two inlets of the three-way regulating valve are respectively connected to the outlet of the check valve and the outlet of the bypass pipeline, and the outlet of the three-way regulating valve is connected to the heating user's pipeline network; the temperature sensor is used to detect the supply water temperature at the outlet of the three-way regulating valve and control the opening degree of the three-way regulating valve according to the supply water temperature; and a conventional heat source pipeline in the shaft seal cooler heat source recovery system, which is connected to the outlet pipeline of the three-way regulating valve via a third valve.

[0007] This includes a hot water storage tank, whose inlet is connected to the cold-side outlet pipe of the plate heat exchanger via a hot water storage inlet branch pipe. A fourth valve and a hot water storage circulation pump are sequentially installed on the hot water storage inlet branch pipe along the water flow direction. The outlet of the hot water storage tank is connected to the heating return water main pipe via a hot water storage outlet branch pipe. A fifth valve is installed on the hot water storage outlet branch pipe. A hot water storage bypass pipe is also connected between the cold-side inlet pipe and the cold-side outlet pipe of the plate heat exchanger. A sixth valve is installed on the hot water storage bypass pipe.

[0008] The hot-side outlet of the plate heat exchanger is connected to the hot well of the turbine condenser via a condensate output pipeline; an exhaust pipeline is also provided at the top of the hot-side outlet of the plate heat exchanger, and the exhaust pipeline is connected to a shaft seal fan to discharge uncondensed gas to the atmosphere.

[0009] This includes a vacuum undisturbed heat exchange system, which comprises an isolated heat exchanger, a shaft seal return steam inlet bypass, a return steam outlet pipeline, and a condensate circulation loop. The isolated heat exchanger has a primary side and a secondary side that are isolated from each other for heat exchange. The inlet end of the shaft seal return steam inlet bypass is used to guide the return steam from the turbine shaft seal system to the secondary side inlet of the isolated heat exchanger. The inlet end of the return steam outlet pipeline is connected to the secondary side outlet of the isolated heat exchanger, and its outlet end is connected to the inlet of the turbine shaft seal cooler. The inlet end of the condensate circulation loop is connected to the condensate outlet pipeline of the turbine shaft seal cooler, and its outlet end is connected to the hot well of the turbine condenser. The primary side of the isolated heat exchanger is connected in series in the condensate circulation loop.

[0010] The condensate circulation loop is equipped with a condensate circulation pump located downstream of its starting end; the primary inlet of the isolation heat exchanger is connected to the outlet pipe of the condensate circulation pump, and its primary outlet is connected to the condensate pipe leading to the hot well.

[0011] The hot-side outlet of the plate heat exchanger is connected to the condensate pipeline leading to the hot well via a pipeline.

[0012] The present invention has the following beneficial effects: This invention utilizes an upstream buffer chamber integrating a phase change material (PCM) tube bundle and a downstream flash evaporation chamber and mixing heater. When the heat source temperature and flow rate fluctuate drastically due to peak load, the PCM first performs thermal buffering and energy storage. The stabilized condensate then generates steam through throttling flash evaporation, and the latent heat of the steam is efficiently utilized by the mixing heater. This overcomes the shortcomings of simple single-stage flash evaporation devices, such as unstable steam production and parameters affecting heat exchange efficiency during heat source fluctuations. It achieves stable and efficient recovery and utilization of intermittent, drastically fluctuating low-grade industrial waste heat.

[0013] This invention integrates a porous capillary evaporation element within a buffer chamber, exposing its working end to a low-pressure gas phase space connected to the flash evaporation chamber, thus forming an adaptive pre-flash evaporation. When the heat source temperature rises, capillary evaporation automatically intensifies, rapidly consuming excess heat and generating additional steam; conversely, it automatically weakens when the temperature decreases. This achieves millisecond-level rapid response and autonomous adjustment to fluctuating thermal energy, enhancing the system's ability to withstand transient thermal shocks and improving energy efficiency and operational stability under all operating conditions.

[0014] This invention achieves the direct recovery of waste heat from the turbine shaft seal return steam by setting up a basic heat exchange loop consisting of a heat source introduction pipeline, a plate heat exchanger, and a heating return water main pipeline, and by cooperating with a bypass pipeline and a temperature regulation device. It can also stably control the temperature of the heated water supply within a set range, thereby achieving the goal of using waste heat to meet the heating needs of the plant area and reducing external energy consumption.

[0015] This invention adds a heat storage subsystem including a hot water storage tank, a heat storage circulation pump and related valves, and connects a heat storage bypass pipe in parallel on the plate heat exchanger side. This enables the storage of excess heat when the heat source is sufficient and the release of stored heat when the heat source is insufficient. It can also optimize the pipeline under heat release conditions, thereby achieving the goals of smoothing heat source fluctuations, extending the waste heat utilization time and reducing system resistance.

[0016] This invention establishes an independent vacuum undisturbed heat exchange system, employs an isolated heat exchanger to achieve indirect heat exchange between shaft seal return steam and condensate, and uses condensate as an intermediate medium to provide a heat source for the plate heat exchanger. This achieves the goal of establishing two physical isolations between the heating water system and the unit's vacuum system, thereby achieving the purpose of efficiently recovering waste heat while fundamentally isolating the potential risks to condenser vacuum safety posed by heating-side leakage. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the system of the present invention; Figure 2 This is a schematic diagram of the adjustable flow element of the present invention.

[0018] The reference numerals in the figure are as follows: 1. Heat source inlet pipeline; 2. Plate heat exchanger; 3. Bypass pipeline; 4. Three-way regulating valve; 5. Conventional heat source pipeline; 6. Temperature sensor; 7. Heating user network; 8. Hot water storage tank; 9. Hot water storage inlet branch pipe; 10. Hot water storage outlet branch pipe; 11. Heating return water main pipeline; 12. Hot water storage bypass pipe; 13. Hot well; 14. Exhaust pipeline; 15. Shaft seal fan; 16. Isolated heat exchanger; 17. Shaft seal return... 18. Steam inlet bypass; 19. Steam return outlet pipeline; 20. Condensate circulation loop; 21. Turbine shaft seal cooler; 22. Primary side; 23. Secondary side; 24. Buffer chamber; 25. Flash chamber; 26. Mixing heater; 27. Horizontal pressure-bearing baffle; 28. Phase change material tube bundle; 29. ​​Porous capillary evaporator element; 20. Metal bellows; 21. Capillary connecting pipe; 22. Transmission lever; 33. Push rod. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Please see Figures 1 to 2 The invention provides a technical solution: This embodiment provides a heat source recovery system for the shaft seal cooler of a pure condensing peak-shaving gas turbine unit. It is used to recover the waste heat of low-pressure return steam generated by the turbine shaft seal system during unit operation, in order to meet the winter heating needs of the power plant area, thereby reducing or even replacing the consumption of external natural gas or electricity by the original heating system, and achieving energy saving and consumption reduction.

[0021] The system mainly includes a heat source inlet pipe 1, a plate heat exchanger 2, a heating return water main pipe 11, and a temperature regulating device. Among them, the heat source inlet pipe 1 serves as the heat input channel of the system, and one end of it is connected to the return steam header of the turbine shaft seal system, which guides the shaft seal return steam that originally went to the shaft seal cooler to the hot side inlet of the plate heat exchanger 2 of this system.

[0022] The cold-side inlet of the plate heat exchanger 2 is connected to the return water main of the power plant heating system through the heating return water main pipeline 11, thereby introducing the heating return water with a lower temperature.

[0023] Inside the plate heat exchanger 2, the shaft seal return steam flows in the hot side channel and releases latent heat and sensible heat. This heat is transferred through the efficient plates to the heating return water flowing in the opposite direction in the cold side channel, raising its temperature. The cooled shaft seal return steam is partially condensed into water.

[0024] Specifically, at the bottom of the hot side of the plate heat exchanger 2, the condensate formed is led back to the hot well 13 of the turbine condenser through a condensate outlet pipe. This allows the condensate to be automatically and continuously drawn into the hot well 13 under pressure differential, thus recovering it and reintroducing it into the power plant's steam-water circulation system, achieving closed-loop recovery and utilization of the working fluid. Meanwhile, since the shaft seal return steam usually contains a small amount of non-condensable gases such as air, these gases do not liquefy during heat exchange. If they accumulate in the plate heat exchanger 2, they will severely affect the heat exchange efficiency. Therefore, an exhaust pipe 14 is installed at the top of the hot side passage of the plate heat exchanger 2, which is connected to a shaft seal fan 15. The shaft seal fan 15 operates continuously, actively extracting the non-condensable gases collected at the top of the heat exchanger and discharging them into the atmosphere, thereby effectively ensuring the heat exchange performance of the hot side passage of the plate heat exchanger 2 and the stable operation of the system.

[0025] A bypass pipe 3 is installed in parallel upstream of the cold side outlet pipe of plate heat exchanger 2.

[0026] The bypass pipe 3 allows a portion of the heating return water to flow directly downstream of the system without being heated by the plate heat exchanger 2. The system's temperature regulation device is located downstream of the cold-side outlet pipe of the plate heat exchanger 2, with its inlet connected to both the cold-side outlet of the plate heat exchanger 2 (i.e., the heated water flow) and the outlet of the bypass pipe 3 (i.e., the unheated bypass return water). The core function of the temperature regulation device is to mix these two water flows of different temperatures in a proportional manner, precisely control the temperature of the mixed water at its outlet within the set heating temperature range, and finally deliver the mixed and temperature-regulated water to the heating user's pipe network 7 to complete the heating supply.

[0027] A first valve for controlling the on / off of the shaft seal return steam is installed on the heat source inlet pipe 1; a second valve for controlling the on / off of this branch is installed on the bypass pipe 3. A check valve is also installed at the cold side outlet pipe of the plate heat exchanger 2 to prevent backflow of water in the heating system.

[0028] The temperature regulating device specifically includes a three-way regulating valve 4 and a temperature sensor 6. The two inlets of the three-way regulating valve 4 are respectively connected to the outlet of the check valve (hot water from the plate heat exchanger 2) and the outlet of the bypass pipe 3 (cold water from the bypass), and its outlet is connected to the heating user's pipe network 7. The temperature sensor 6 detects the temperature of the mixed water supply at the outlet of the three-way regulating valve 4 in real time and feeds the signal back to the control system.

[0029] The control system adjusts the opening ratio of the two inlets inside the three-way regulating valve 4 based on the deviation between the measured value and the set value of the temperature sensor 6. For example, when the supply water temperature is detected to be higher than the set value, the proportion of cold water from the bypass pipe 3 is increased and the proportion of hot water from the plate heat exchanger 2 is decreased; conversely, the proportion of hot water is increased and the proportion of cold water is decreased, thereby achieving control of the supply water temperature.

[0030] Furthermore, considering that the power plant still needs to provide continuous heating even when the gas turbine unit is shut down and there is no shaft seal return steam available, this system also integrates a conventional heat source pipeline 5 as a backup heat source. This conventional heat source pipeline 5 is connected to the outlet pipeline of the three-way regulating valve 4 via a third valve. When the unit is shut down, the first valve can be closed and the third valve opened to introduce high-temperature water from the power plant's existing gas boiler, electric boiler, or other conventional heat sources, which is then transported to the heating network via the three-way regulating valve 4.

[0031] This embodiment also includes a heat storage subsystem. The core of this system is a hot water storage tank 8. The inlet of the hot water storage tank 8 is connected to the cold-side outlet pipe of the plate heat exchanger 2 via a heat storage inlet branch pipe 9, thereby obtaining pre-heated heating water. A fourth valve and a heat storage circulation pump are sequentially installed along the water flow direction on the heat storage inlet branch pipe 9. When the unit is running, the shaft seal return steam heat is sufficient, and the current heating demand is lower than the recoverable heat, the fourth valve can be opened and the heat storage circulation pump can be started, thereby actively pumping a portion of the hot water from the plate heat exchanger 2 into the hot water storage tank 8 for storage, achieving heat storage. The outlet of the hot water storage tank 8 is connected to the heating return water main pipe 11 via a heat storage outlet branch pipe 10, and a fifth valve is installed on this branch pipe.

[0032] When the unit stops operating and the shaft seal return steam heat source is interrupted, the fifth valve can be opened. At this time, the high-temperature water stored in the hot water storage tank 8 will automatically flow into the heating return water main pipe 11 under the action of the residual pressure in the tank and the system pressure difference, and mix with the low-temperature return water returning from the user end, thereby supplementing the system with heat, effectively extending the duration of waste heat heating, and reducing the dependence on conventional heat sources.

[0033] In addition, to optimize the hydraulic characteristics of the pipeline and reduce unnecessary circulation resistance when the unit is shut down, a heat storage bypass pipe 12 is connected between the cold-side inlet pipe and the cold-side outlet pipe of the plate heat exchanger 2, and a sixth valve is installed on it. When the heat storage tank is activated to release heat, the sixth valve can be opened simultaneously. In this way, most of the heating return water from users can flow directly through this heat storage bypass pipe 12, thus bypassing the plate heat exchanger 2 which has no heat source and only flow resistance, and flowing directly to the three-way regulating valve 4 to participate in mixing, making the system circulation smoother and avoiding heat loss.

[0034] The vacuum level in the turbine condenser is a critical indicator of power plant safety. Deterioration of the vacuum level can directly lead to a significant decrease in unit efficiency, and in severe cases, can even cause the unit to trip, resulting in substantial economic losses.

[0035] In the above scheme, the plate heat exchanger 2 is directly connected to the shaft seal return steam system via the heat source inlet pipe 1, and the shaft seal system is connected to the condenser vacuum. Although the scheme is designed with pipes and valves, in some cases, such as when the plate heat exchanger 2 or its connected heating water side pipe leaks, outside air may be directly drawn into the vacuum system through the leak point, posing a potential risk of vacuum disruption.

[0036] Therefore, this embodiment further proposes a vacuum undisturbed heat exchange system, which mainly includes an isolated heat exchanger 16, a shaft seal return steam inlet bypass 17, a return steam outlet pipeline 18, and a condensate circulation loop 19.

[0037] Among them, the isolation heat exchanger 16 is the core isolation device. Its interior is separated into two independent flow channels, the primary side 161 and the secondary side 162, by a metal wall, allowing heat to be transferred only through the wall.

[0038] Specifically, the return steam from the turbine shaft seal system is first guided to the secondary side 162 inlet of the isolation heat exchanger 16 via the shaft seal return steam inlet bypass 17. After flowing and releasing heat in the secondary side 162, the cooled return steam is completely transported back to the original turbine shaft seal cooler 20 inlet through the return steam outlet pipe 18, thus minimizing the intervention in the original shaft seal system process.

[0039] Meanwhile, the inlet end of the condensate circulation loop 19 is connected to the condensate outlet pipe of the turbine shaft seal cooler 20, from which a stream of clean, low-temperature condensate is drawn out; the outlet end of the condensate circulation loop 19 is connected to the hot well 13 of the turbine condenser.

[0040] A condensate circulation pump is located downstream of the starting point of the condensate circulation loop 19 to provide power for the condensate circulation. The primary side 161 of the isolated heat exchanger 16 is connected in series to this condensate circulation loop 19. Specifically, its primary side inlet is connected to the outlet pipe of the condensate circulation pump, and its primary side outlet is connected to the condensate pipe leading to the hot well 13. When the condensate flows through the primary side 161, it absorbs the heat transferred from the shaft seal return steam of the secondary side 162 and is heated itself.

[0041] After being heated, the condensate is divided into two streams after flowing out of the primary side outlet of the isolation heat exchanger 16. The main stream returns directly to the condenser hot well 13, and the heat it carries can re-enter the power generation thermal cycle, increasing the feedwater temperature. The branch stream becomes a new heat source working fluid for the plate heat exchanger 2.

[0042] Specifically, the hot-side inlet of plate heat exchanger 2 is reconnected to the primary-side outlet pipe of isolation heat exchanger 16 to introduce this portion of hot condensate. In plate heat exchanger 2, after the hot condensate transfers heat to the heating return water, its own temperature decreases, and it returns through the pipe at its hot-side outlet, flowing into the condensate pipe leading to hot well 13, and finally all of it returns to the condenser.

[0043] A condensate treatment device is installed on the heat source inlet pipe 1. The condensate treatment device includes a pressure-bearing shell, which is divided into an upstream buffer chamber 21 and a downstream flash chamber 22 by a horizontal pressure-bearing baffle.

[0044] In the condensate treatment device, the horizontal pressure-bearing baffle 24 not only serves to separate the upper and lower chambers, but the connecting port on it is also the flow channel node connecting the buffer chamber 21 and the flash evaporation chamber 22.

[0045] An adjustable flow element is provided at the connection port. The adjustable flow element specifically includes a valve body, a valve core, a temperature-sensing drive unit, and a displacement conversion mechanism.

[0046] The valve body has a main channel, whose inlet and outlet are respectively connected to the bottom of the buffer chamber 21 and the flash chamber 22, forming the only controlled path for condensate to flow from the buffer chamber to the flash chamber.

[0047] The valve body contains a valve core that can move precisely along its own axis. This valve core is usually designed as a cone or a plunger with a specific profile. Its axial displacement can linearly and continuously change the minimum flow cross-sectional area of ​​the main flow channel, thereby achieving stepless adjustment from fully open to near closed. This is similar to the working principle of a shut-off valve or a regulating needle valve.

[0048] The temperature-sensing drive unit is a sealed metal bellows 27, filled with a working fluid that functions identically to the phase change material in the phase change material bundle 25 within the buffer chamber 21. The internal cavity of the metal bellows 27 is connected to the phase change material bundle 25 via a capillary connector 28, achieving working fluid communication and pressure balance. This allows the working fluid within the metal bellows 27 to reflect in real-time the state and volume changes of the phase change material in the phase change material bundle 25 due to condensate temperature variations.

[0049] The displacement conversion mechanism is responsible for amplifying and converting minute volume changes into reliable valve core actuation. It includes a transmission lever 29, a push rod 30, and a return spring. The transmission lever 29 has a fixed fulcrum in the middle. The two ends of the push rod 30 are respectively hinged to the free end of the metal bellows 27 and the first end of the transmission lever 29 to transmit motion. The return spring acts on the valve core, and its elastic force always points in the direction of driving the valve core to move in the opening direction, ensuring that the valve can automatically return to its open position when the driving force disappears.

[0050] When the condensate temperature rises, the phase change material in the phase change material bundle 25 and the working fluid inside the metal bellows 27 absorb heat and undergo phase change expansion, pushing the metal bellows 27 to elongate. This, in turn, drives the valve core to close slightly via a lever mechanism, increasing flow resistance and preventing excessive high-temperature water from entering the flash chamber 22. Conversely, when the temperature decreases, the working fluid solidifies and contracts, and the valve core opens wider under the action of the return spring. This allows the valve opening to adapt to fluctuations in the heat source temperature, automatically maintaining the system near the optimal flash evaporation conditions without the need for external energy or control signals, greatly improving the system's response speed, operational stability, and reliability.

[0051] According to thermodynamic principles, the saturation temperature (boiling point) of a liquid decreases as pressure decreases. When condensate at a certain temperature is throttled and depressurized, its temperature will exceed the new boiling point under the current low-pressure environment, causing some of the liquid water to instantly absorb its own heat and boil and vaporize. This process is called flash evaporation. After flash evaporation is completed, a two-phase system of vapor and liquid will naturally form in the flash chamber 22. At this time, the top is filled with steam carrying a large amount of latent heat of vaporization, while the bottom is the remaining condensate with a correspondingly lower temperature.

[0052] The steam accumulation zone at the top of the flash chamber 22 is connected to the hot-side inlet of the mixing heater 23 via a pipeline, guiding all the generated steam to the mixing heater 23. The mixing heater 23 is a direct-contact heat exchange device, with its cold-side inlet connected to the main heating return water pipeline 11 from the coldest end of the heating system. Inside the mixing heater 23, the introduced steam mixes directly with the low-temperature heating return water and condenses rapidly, transferring its latent heat of vaporization almost without loss and efficiently to the heating return water, resulting in a significant initial temperature increase.

[0053] Subsequently, the pre-heated heating return water flows out from the outlet of the mixing heater 23 and is transported to the cold side inlet of the plate heat exchanger 2, awaiting further heating. At the same time, the condensate at the bottom of the flash chamber 22, whose temperature has decreased, is also led to the hot side inlet of the plate heat exchanger 2 through the heat source introduction pipe 1.

[0054] The buffer cavity 21 is provided with a phase change material tube bundle 25. The tube side of the phase change material tube bundle 25 is sealed with phase change material, and the shell side of the phase change material tube bundle 25 constitutes the flow path of condensate through the buffer cavity 21. These phase change materials are typically inorganic hydrated salts or paraffin compounds with melting points within a specific range. Their core characteristic is that they can absorb or release a large amount of latent heat during a solid-liquid phase transition while maintaining a relatively constant temperature. Therefore, the phase change material is given a predetermined phase transition temperature. It must be within the range of the condensate temperature flowing through this point under typical stable peak load conditions. The peak condensate temperature that may occur when the unit passes through this area during a rapid load increase transient. between.

[0055] When drastic load fluctuations caused by peak shaving trigger a sudden rise in condensate temperature, i.e., when high-temperature condensate (temperature > 100°C) is generated... As heat flows through the shell side, it is transferred through the tube wall, and the phase change material absorbs the excess heat. The high-grade heat begins to melt, storing the heat as potential energy, while protecting downstream equipment from thermal shock and stabilizing the heat source quality. When the condensate temperature drops below At this time, the phase change material solidifies in the reverse direction, releasing the stored latent heat to supplement the heating of the flowing condensate.

[0056] As a more efficient extended design, the adjustable flow element can be configured as a multi-stage series of pressure-reducing nozzles to achieve multi-effect flash evaporation. In this configuration, condensate, initially stabilized by the buffer chamber 21, flows sequentially through these progressively enlarging nozzles, with the pressure being reduced in stages, resulting in multiple flash evaporations at different pressure levels and generating multiple streams of steam with different saturation temperatures. These steams of different grades can be exported separately to precisely match the heating or process heat requirements at different temperature levels within the plant area, achieving tiered and precise utilization of thermal energy. For simplicity, the above description uses single-stage flash evaporation as an example, but those skilled in the art should understand that employing multi-effect flash evaporation to achieve finer energy fractionation is still within the scope of protection of this invention.

[0057] In a preferred embodiment of the present invention, a porous capillary evaporation element 26 is further integrated in the buffer chamber 21 of the condensate treatment device. Specifically, a plurality of porous capillary evaporation elements 26 are arranged in an array in the shell-side flow channel around the phase change material tube bundle 25. The porous capillary evaporation element 26 is usually made of sintered metal powder (such as copper powder or stainless steel powder) and is filled with interconnected pores to form a strong capillary structure.

[0058] Its bottom is firmly installed and submerged in the condensate in the flow channel, while its top extends out of the liquid surface and into the reserved gas phase space between the buffer chamber 21 and the phase change material tube bundle 25. The reserved gas phase space at the top of the buffer chamber 21 is connected to the steam accumulation area at the top of the flash chamber 22 through a steam balance pipe, so that the reserved gas phase space and the gas phase space at the top of the flash chamber 22 are maintained in the same low-pressure environment. Its core working mechanism is to use the capillary force of the material itself to continuously adsorb liquid condensate from the main body of the flow channel to the exposed top end of the element.

[0059] The porous capillary evaporation element 26, immersed in condensate, generates strong capillary forces through its densely packed interconnected pores. These forces continuously adsorb and transport liquid water to the top of the element. When the adsorbed liquid water film reaches the top of the reserved gas phase space exposed to the aforementioned low-pressure gas phase environment, the liquid water is instantly superheated because the gas phase pressure there is lower than the saturation pressure corresponding to the liquid water temperature. Consequently, the water film boils violently on the vast pore surface area, directly transforming from a liquid to a gaseous state. This flash evaporation process absorbs a large amount of latent heat of vaporization, which comes directly from the liquid water itself and the bulk condensate within the flow channel, thus achieving rapid cooling of the condensate. The resulting low-temperature steam is then captured by the steam collection hood above and extracted for use through the steam outlet pipe.

[0060] When the unit load increases and the temperature of the incoming condensate rises, the capillary flow rate and evaporation intensity will automatically increase based on physical principles, generating more steam; conversely, when the water temperature decreases, evaporation will automatically decrease. The generated steam is captured by the overhead steam collection hood and directly discharged for utilization.

[0061] Specifically, when the unit rapidly increases its load and the heat of the shaft seal return steam increases sharply, the condensate temperature rises. Based on physical principles, the capillary water transport and evaporation intensity of the porous capillary evaporation element 26 are automatically enhanced, enabling it to extract and consume excess heat from the mainstream condensate more quickly and convert it into usable steam. This not only rapidly buffers the thermal shock and protects downstream equipment, but also instantly increases the heating capacity. Conversely, when the heat source weakens, the process automatically weakens to avoid overcooling.

[0062] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A heat source recovery system for a shaft seal cooler of a peak-shaving gas turbine unit, characterized in that: The system includes a heat source inlet pipe (1), a plate heat exchanger (2), a heating return water main pipe (11), and a vacuum undisturbed heat exchange system. The vacuum undisturbed heat exchange system is used to exchange heat between the return steam of the turbine shaft seal system and the condensate in the condensate circulation loop (19). The heat source inlet pipe (1) is used to introduce the condensate after heat exchange in the vacuum undisturbed heat exchange system into the plate heat exchanger (2) and exchange heat with the supply water of the heating return water main pipe (11) before delivering it to the heating user network (7). A condensate treatment device is installed on the heat source inlet pipe (1). The condensate treatment device includes a pressure-bearing shell, and the interior of the pressure-bearing shell is connected by a horizontal pressure-bearing partition. The plate (24) is divided into an upstream buffer chamber (21) and a downstream flash chamber (22); the horizontal pressure-bearing partition (24) is provided with a connection port between the buffer chamber (21) and the flash chamber (22), and an adjustable flow element is provided at the connection port; the steam accumulation area at the top of the flash chamber (22) is connected to the hot side inlet of the mixing heater (23), and the condensate area at the bottom of the flash chamber (22) is connected to the hot side inlet of the plate heat exchanger (2); the cold side inlet of the mixing heater (23) is connected to the heating return water main pipeline (11), and the outlet of the mixing heater (23) is connected to the cold side inlet of the plate heat exchanger (2).

2. The heat source recovery system for the shaft seal cooler of a peak-shaving gas turbine unit as described in claim 1, characterized in that: A phase change material (PCM) tube bundle (25) is disposed inside the buffer chamber (21). The PCM tube bundle (25) contains a sealed PCM material in its tube side, and the shell side of the PCM tube bundle (25) forms the flow path for condensate to flow through the buffer chamber (21). The PCM material has a set phase change temperature. The phase transition temperature The value is between the condensate temperature flowing through this point under stable peak load conditions. The peak condensate temperature that occurs when the unit passes through this area during a rapid load increase transient process. between.

3. The heat source recovery system for the shaft seal cooler of a peak-shaving gas turbine unit as described in claim 2, characterized in that: The adjustable flow element includes a valve body, a valve core, a temperature-sensing drive unit, and a displacement conversion mechanism; the valve body has a main flow channel, the inlet and outlet of which are respectively connected to the bottom of the buffer chamber (21) and the flash chamber (22); the valve body has a valve core that can move along its axis, and the movement of the valve core can change the flow cross-sectional area of ​​the main flow channel; the temperature-sensing drive unit is a sealed metal bellows (27), the inside of which is filled with phase change material, and the internal cavity of the metal bellows (27) is connected to the buffer chamber (21) through a capillary connecting tube (28). The working fluid is connected and the pressure is balanced in the tube side of the phase change material tube bundle (25) inside; the displacement conversion mechanism includes a transmission lever (29), a push rod (30) and a return spring; the transmission lever (29) has a fixed fulcrum in the middle; the two ends of the push rod (30) are respectively hinged to the free end of the metal bellows (27) and the first end of the transmission lever (29); the second end of the transmission lever (29) is hinged to the valve stem that drives the valve core; the return spring acts on the valve core and its elastic force is set to drive the valve core to move in the opening direction.

4. The shaft seal cooler heat source recovery system for a peak-shaving gas turbine unit as described in claim 3, characterized in that: Multiple porous capillary evaporation elements (26) are provided in the buffer chamber (21). One end of the porous capillary evaporation element (26) is immersed in the condensate flowing through the shell side of the phase change material tube bundle (25), and the other end extends and is exposed in the reserved gas phase space between the buffer chamber (21) and the phase change material tube bundle (25). The reserved gas phase space at the top of the buffer chamber (21) is connected to the steam accumulation area at the top of the flash chamber (22) through a steam balance pipe, so that the pressure of the reserved gas phase space and the gas phase space at the top of the flash chamber (22) are the same. A steam collection hood is provided in the reserved gas phase space. The steam collection hood covers the exposed end of the porous capillary evaporation element (26), and the steam collection hood is connected to the hot side inlet of the mixing heater (23) through a steam outlet pipe.

5. The shaft seal cooler heat source recovery system for a peak-shaving gas turbine unit as described in claim 1, characterized in that: The vacuum undisturbed heat exchange system includes an isolated heat exchanger (16), a shaft seal return steam inlet bypass (17), and a return steam outlet pipe (18); the isolated heat exchanger (16) has a primary side (161) and a secondary side (162) that are isolated from each other for heat exchange; the inlet end of the shaft seal return steam inlet bypass (17) is used to guide the return steam of the turbine shaft seal system to the secondary side inlet of the isolated heat exchanger (16); the inlet end of the return steam outlet pipe (18) is connected to the secondary side outlet of the isolated heat exchanger (16), and its outlet end is connected to the inlet of the turbine shaft seal cooler (20); the inlet end of the condensate circulation loop (19) is connected to the condensate outlet pipe of the turbine shaft seal cooler (20), and its outlet end is connected to the hot well (13) of the turbine condenser; the primary side (161) of the isolated heat exchanger (16) is connected in series in the condensate circulation loop (19).

6. The shaft seal cooler heat source recovery system for a peak-shaving gas turbine unit as described in claim 1, characterized in that: The heat source inlet pipe (1) is connected to the hot side inlet of the plate heat exchanger (2); a bypass pipe (3) is connected in parallel between the cold side inlet and the cold side outlet of the plate heat exchanger (2); a temperature regulating device is also provided downstream of the cold side outlet pipe of the plate heat exchanger (2), and the inlet end of the temperature regulating device is connected to both the cold side outlet pipe of the plate heat exchanger (2) and the outlet of the bypass pipe (3); the outlet of the temperature regulating device delivers the mixed and temperature-regulated water to the heating user network (7).

7. The heat source recovery system for the shaft seal cooler of a peak-shaving gas turbine unit as described in claim 6, characterized in that: A first valve for controlling the on / off of return steam is provided on the heat source inlet pipe (1); a second valve for controlling the on / off of bypass pipe (3) is provided on the bypass pipe (3); a check valve is provided at the cold side outlet pipe of the plate heat exchanger (2); the temperature regulating device includes a three-way regulating valve (4) and a temperature sensor (6). The two inlets of the three-way regulating valve (4) are respectively connected to the outlet of the check valve and the outlet of the bypass pipe (3). The outlet of the three-way regulating valve (4) is connected to the heating user pipe network (7). The temperature sensor (6) is used to detect the water supply temperature at the outlet of the three-way regulating valve (4) and control the opening degree of the three-way regulating valve (4) according to the water supply temperature. The shaft seal cooler heat source recovery system also includes a conventional heat source pipe (5). The conventional heat source pipe (5) is connected to the outlet pipe of the three-way regulating valve (4) through a third valve.

8. The heat source recovery system for the shaft seal cooler of a peak-shaving gas turbine unit as described in claim 7, characterized in that: The hot side outlet of the plate heat exchanger (2) is connected to the hot well (13) of the steam turbine condenser through a condensate output pipeline; an exhaust pipeline (14) is also provided at the top of the hot side outlet of the plate heat exchanger (2), and the exhaust pipeline (14) is connected to a shaft seal fan (15) for discharging uncondensed gas to the atmosphere.

9. A heat source recovery system for a shaft seal cooler of a peak-shaving gas turbine unit as described in claim 5, characterized in that: A condensate circulation pump is installed on the condensate circulation loop (19) and is located downstream of its starting end; the primary side inlet of the isolation heat exchanger (16) is connected to the outlet pipe of the condensate circulation pump, and the primary side outlet of the isolation heat exchanger (16) has two branches, one of which is connected to the condensate pipe leading to the hot well (13), and the other is connected to the heat source introduction pipe (1).

10. A heat source recovery system for a shaft seal cooler of a peak-shaving gas turbine unit as described in claim 9, characterized in that: The hot-side outlet of the plate heat exchanger (2) is connected via a pipeline to the condensate pipeline leading to the hot well (13).

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