A steam turbine counterflow rapid cooling system and method

Abstract

This application relates to the field of steam turbine cooling technology, specifically to a counter-current rapid cooling system and method for steam turbines. The system includes a steam turbine body and a rapid cooling device. The rapid cooling device comprises a pressurized fan, a temperature box heater, an electric heater, a first heat exchanger, a second heat exchanger, and a third electric temperature box heater, all connected via inlet pipes to the exhaust side of the high-pressure cylinder, intermediate-pressure cylinder, and two low-pressure cylinders in the steam turbine body. The inlet side of each cylinder is connected to the temperature box heater via a return pipe. The method includes collecting the initial inlet temperature of each cylinder, activating the rapid cooling device to preheat the inlet pipes of the high-pressure and intermediate-pressure cylinders to the initial inlet temperature, then allowing the cooling medium to flow counter-currently into the exhaust side of each cylinder and out from the inlet side to form a circulation. The inlet temperature is dynamically adjusted based on the relationship between the real-time temperature gradient and the initial temperature gradient until the maximum temperature of all cylinders drops to the turning gear threshold. This invention achieves low thermal stress, uniform and controllable rapid cooling, shortening the downtime maintenance cycle.

Description

Technical Field

[0001] This application relates to the field of steam turbine cooling technology, specifically to a counter-current rapid cooling system and method for steam turbines. Background Technology

[0002] In the energy and power sector, steam turbines, as core equipment for converting thermal energy into mechanical energy, are widely used in thermal power generation, nuclear power plants, and industrial drives. After long-term continuous operation under high temperature and high pressure conditions, steam turbines accumulate a large amount of heat in their internal metal components (such as rotors, cylinders, and blades). When the unit needs to be shut down for maintenance, malfunction, or peak shaving, these high-temperature components must be cooled to a safe temperature to facilitate subsequent turning gear shutdown, internal inspection, or maintenance work. However, steam turbine components have complex structures and large heat capacities. Traditional natural cooling methods mainly rely on the cylinder itself radiating heat to the environment, a process that is extremely time-consuming, typically requiring 10 to 15 days or even longer, severely impacting the equipment utilization rate and operational economy of power plants.

[0003] To address the cooling needs of steam turbines after shutdown, several active rapid cooling systems and methods have been developed in the prior art. These solutions typically employ external rapid cooling devices, such as fans and heaters, to heat the cooling medium (such as air or steam) to a certain temperature before introducing it into the steam turbine through specific pipelines. The cooling medium flows within the cylinder, exchanging heat with the high-temperature metal components, absorbing heat, and then exiting from the outlet, thereby carrying away the heat from the cylinder and accelerating cooling. Some solutions also incorporate multiple intake or return air channels, attempting to cool the high-pressure, intermediate-pressure, and low-pressure cylinders separately to improve cooling efficiency.

[0004] However, in practical applications, existing rapid cooling systems still have significant shortcomings: In existing rapid cooling systems, the flow direction of the cooling medium inside the turbine is usually the same as the flow direction of the medium during normal turbine operation (i.e., from the inlet side to the exhaust side). Under this co-current cooling method, the higher-temperature cooling medium first enters the inlet side with the highest temperature, causing the metal temperature on the inlet side of the cylinder to drop sharply, while the exhaust side cools down slowly, which in turn increases the temperature gradient along the medium flow direction inside the cylinder. The high temperature gradient will induce huge thermal stress, which may lead to rotor bending, cylinder deformation, cracks, or even equipment damage. At the same time, since the initial temperature distribution of the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder differs significantly after shutdown, existing systems use a uniform heating path or a single heating source to supply air to each cylinder, making it difficult to accurately match the independent initial inlet temperature of each cylinder. This easily leads to some cylinders cooling too quickly while others are not cooled enough, further worsening the thermal stress distribution. As a result, existing rapid cooling technology is often forced to reduce the cooling rate or even be abandoned in practical applications due to the difficulty in controlling thermal stress, and instead rely on time-consuming natural cooling. Summary of the Invention

[0005] To address the problems in existing co-current rapid cooling systems for steam turbines, where the cooling medium is introduced from the steam inlet side, causing a rapid drop in the high-temperature region and exacerbating the internal temperature gradient of the cylinder, resulting in excessive thermal stress, and where a unified air supply path for each cylinder cannot match their different initial inlet air temperatures, this application provides a counter-current rapid cooling system and method for steam turbines. By introducing the cooling medium from the exhaust side of each cylinder in a counter-current manner and drawing it out from the steam inlet side, and coordinating with independent air supply circuits to control the inlet air temperature of each cylinder, the system dynamically adjusts the inlet air temperature during the cooling process based on the relationship between the real-time temperature gradient and the initial temperature gradient, effectively reducing thermal stress and achieving uniform and rapid cooling.

[0006] In a first aspect, this application provides a counter-current rapid cooling system for a steam turbine, including a steam turbine body and a rapid cooling device; The turbine body includes a high-pressure cylinder, an intermediate-pressure cylinder, and two low-pressure cylinders. The exhaust side of the high-pressure cylinder is connected to the inlet side of the intermediate-pressure cylinder through a high-pressure exhaust pipe. The exhaust side of the intermediate-pressure cylinder is connected to the inlet side of the two low-pressure cylinders through two intermediate-pressure exhaust pipes respectively. The rapid cooling device includes a pressurizing fan, an electric heater, a temperature chamber heater, a first heat exchanger, a second heat exchanger, and a third electric temperature chamber heater. The outlet of the pressurizing fan is connected to the inlet of the electric heater through a fan outlet pipe. The outlet of the electric heater is connected to the inlet of the temperature chamber heater through a heater outlet pipe. The outlet of the temperature chamber heater is connected to the inlet of the first heat exchanger through a first air supply pipe. The outlet of the temperature chamber heater is connected to the inlet of the second heat exchanger through a second air supply pipe. The outlet of the first heat exchanger is connected to the exhaust side of the high-pressure cylinder through a fast-cooling inlet pipe on the high-pressure cylinder side, and the outlet of the second heat exchanger is connected to the exhaust side of the intermediate-pressure cylinder through a fast-cooling inlet pipe on the intermediate-pressure cylinder side. The outlet of the pressurizing blower is connected to the inlet of the third electric temperature chamber heater through the third air supply pipe. The outlet of the third electric temperature chamber heater is connected to the exhaust side of the two low-pressure cylinders through the low-pressure cylinder side rapid cooling inlet pipe. The steam inlet side of the high-pressure cylinder is connected to the return gas end of the temperature chamber heater through the high-pressure cylinder side rapid cooling return gas pipe. The steam inlet side of the intermediate-pressure cylinder is connected to the return gas end of the temperature chamber heater through the intermediate-pressure cylinder side rapid cooling return gas pipe. The steam inlet sides of the two low-pressure cylinders are respectively connected to the return gas end of the temperature chamber heater through two low-pressure cylinder side rapid cooling return gas pipes.

[0007] It should be further noted that the high-pressure cylinder side rapid cooling intake pipe is equipped with a high-pressure cylinder side rapid cooling intake valve, the intermediate-pressure cylinder side rapid cooling intake pipe is equipped with an intermediate-pressure cylinder side rapid cooling intake valve, the low-pressure cylinder side rapid cooling intake pipe is equipped with a low-pressure cylinder side rapid cooling intake valve corresponding to the low-pressure cylinder, the high-pressure cylinder side rapid cooling return pipe is equipped with two parallel high-pressure cylinder side rapid cooling return valves, the intermediate-pressure cylinder side rapid cooling return pipe is equipped with two parallel intermediate-pressure cylinder side rapid cooling return valves, and the two low-pressure cylinder side rapid cooling return pipes are each equipped with a corresponding low-pressure cylinder side rapid cooling return valve. A high-pressure cylinder-side rapid cooling intake pipe is equipped with a high-pressure cylinder-side rapid cooling intake temperature sensor, a high-pressure cylinder-side rapid cooling return pipe is equipped with a high-pressure cylinder-side rapid cooling return pressure sensor, an intermediate-pressure cylinder-side rapid cooling intake pipe is equipped with an intermediate-pressure cylinder-side rapid cooling intake temperature sensor, an intermediate-pressure cylinder-side rapid cooling return pipe is equipped with an intermediate-pressure cylinder-side rapid cooling return pressure sensor, a low-pressure cylinder-side rapid cooling intake pipe is equipped with a low-pressure cylinder-side rapid cooling intake temperature sensor, and two low-pressure cylinder-side rapid cooling return pipes are each equipped with a corresponding low-pressure cylinder-side rapid cooling return pressure sensor.

[0008] It should be further noted that the outlet of the pressurizing blower (4) is connected to the rapid cooling inlet pipe on the high-pressure cylinder side and the rapid cooling inlet pipe on the medium-pressure cylinder side through the mixing pipe respectively; The section where the mixing pipe connects to the high-pressure cylinder side rapid cooling intake pipe is equipped with a high-pressure cylinder side rapid cooling mixing regulating valve, and the section where the mixing pipe connects to the medium-pressure cylinder side high-pressure cylinder side rapid cooling intake pipe is equipped with a medium-pressure cylinder side rapid cooling mixing regulating valve.

[0009] It should be further noted that a high-pressure reverse heating valve is also installed on the high-pressure cylinder side rapid cooling return pipe; and a medium-pressure cylinder side rapid cooling return flow regulating valve is also installed on the medium-pressure cylinder side rapid cooling return pipe.

[0010] It should be further noted that the high-pressure cylinder side rapid cooling intake pipe is also equipped with a high-pressure reverse heating intake valve, the medium-pressure cylinder side rapid cooling intake pipe is also equipped with a medium-pressure reverse heating intake valve, and the low-pressure cylinder side rapid cooling intake pipe is also equipped with a low-pressure heater front valve.

[0011] It should be further noted that the turbine counter-current rapid cooling system also includes a preheating circulation pipe and a pressure balance pipe. The preheating circulation pipe is connected to the rapid cooling inlet pipe on the high-pressure cylinder side and the rapid cooling inlet pipe on the intermediate-pressure cylinder side. The pressure balance pipe is connected to the rapid cooling return pipe on the intermediate-pressure cylinder side and the two rapid cooling return pipes on the low-pressure cylinder side. A preheating circulation valve is installed on the preheating circulation pipe, and a pressure balance valve is installed on the pressure balance pipe. The high-pressure cylinder side rapid cooling return pipe is also equipped with a high-pressure cylinder side rapid cooling return gas flow sensor and a high-pressure cylinder side rapid cooling return gas pressure sensor. The intermediate-pressure cylinder side rapid cooling return pipe is also equipped with an intermediate-pressure cylinder side rapid cooling return gas flow sensor and an intermediate-pressure cylinder side rapid cooling return gas pressure sensor. The two low-pressure cylinder side rapid cooling return pipes are respectively equipped with corresponding low-pressure cylinder side rapid cooling return gas temperature sensors.

[0012] It should be further noted that an air inlet valve is provided on the blower outlet pipe, a blower vent valve is provided at the outlet of the pressurized blower, a heater vent valve is provided on the heater outlet pipe, a first isolation valve is provided on the first air supply pipe, a second isolation valve is provided on the second air supply pipe, and a third isolation valve is provided on the third air supply pipe. The medium-pressure cylinder side rapid cooling return pipe is connected to the air inlet of the pressurizing blower through a circulation pipe, and the circulation pipe is equipped with a blower recirculation valve.

[0013] It should be further noted that a control box is installed on the rapid cooling device. Each temperature sensor, pressure sensor, and valve in the turbine counter-current rapid cooling system is electrically connected to the control box. The control box includes a processor, which is configured to control the operation of each valve based on the temperature and pressure values ​​collected by each temperature and pressure sensor.

[0014] Secondly, please provide a method for rapid counter-flow cooling of a steam turbine, using the aforementioned rapid counter-flow cooling system for a steam turbine, including the following steps: S1. After the turbine body is shut down and put into turning gear, the exhaust side metal wall temperature of each cylinder and the highest and lowest temperature points of each cylinder are collected. The exhaust side metal wall temperature of each cylinder is taken as the initial intake temperature for the cylinder's rapid cooling device to be put into operation, and the difference between the highest and lowest temperature points is taken as the initial temperature gradient when the cylinder is naturally cooled. The cylinder block includes a high-pressure cylinder, an intermediate-pressure cylinder, and two low-pressure cylinders; S2. Start the rapid cooling device. The cooling medium is drawn in by the pressurized fan and then sequentially delivered to the fan outlet pipe, electric heater, heater outlet pipe, and temperature box heater to heat the cooling medium. The high-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the high-pressure cylinder using a heated cooling medium, and the intermediate-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the intermediate-pressure cylinder. S3. The cooling medium in the temperature chamber heater is sent to the first heat exchanger through the first air supply pipe and to the second heat exchanger through the second air supply pipe. At the same time, the cooling medium is sent to the third electric temperature chamber heater through the third air supply pipe by the pressurized fan to circulate the cooling medium. The cooling medium fed into the first heat exchanger enters the exhaust side of the high-pressure cylinder through the high-pressure cylinder side rapid cooling inlet pipe, flows out from the high-pressure cylinder side inlet pipe, and returns to the return end of the temperature box heater through the high-pressure cylinder side rapid cooling return pipe. The cooling medium fed into the second heat exchanger is sent into the exhaust side of the intermediate pressure cylinder (2) through the rapid cooling inlet pipe on the intermediate pressure cylinder side, flows out from the inlet side of the intermediate pressure cylinder, and returns to the return end of the temperature box heater through the rapid cooling return pipe on the intermediate pressure cylinder side. The cooling medium fed into the third electric temperature chamber heater is heated by the third electric temperature chamber heater and then sent to the exhaust side of the two low-pressure cylinders through the two low-pressure cylinder side rapid cooling intake pipes respectively. It flows out from the intake side of the low-pressure cylinder and then returns to the return end of the temperature chamber heater through the two low-pressure cylinder side rapid cooling return pipes respectively. The heating power of the third electric temperature chamber heater is set to make the temperature of the cooling medium after passing through the third electric temperature chamber heater equal to the lower value of the initial intake temperature of the two low-pressure cylinders. The flow direction of the cooling medium inside the turbine body is opposite to the flow direction of the normal operating medium in the turbine. During the cooling medium circulation process, the highest and lowest temperature points of each cylinder are obtained respectively. The difference between the highest and lowest temperature points of each cylinder is used as the real-time temperature gradient of that cylinder. The intake temperature of the cooling medium of each cylinder is adjusted according to the relationship between the real-time temperature gradient of each cylinder and the corresponding initial temperature gradient. S4. Stop rapid cooling when the maximum temperature inside all cylinders drops to the preset turning temperature threshold.

[0015] It should be further noted that the cooling medium is external air or steam.

[0016] It should be further explained that step S2 specifically includes: Open the first isolation valve, the second isolation valve, the preheating circulation valve, and the fan recirculation valve; close the high-pressure cylinder side rapid cooling intake valve and the medium-pressure cylinder side rapid cooling intake valve. The pressurized fan is started to draw in the cooling medium, which then passes through the fan outlet pipe, the electric heater, and the heater outlet pipe before entering the temperature chamber heater. During this process, the cooling medium is heated. After the heated cooling medium flows out of the temperature box heater, part of it is sent to the high-pressure cylinder side rapid cooling intake pipe through the first air supply pipe and the first heat exchanger, and the other part is sent to the medium-pressure cylinder side rapid cooling intake pipe through the second air supply pipe and the second heat exchanger. The cooling medium supplied to the high-pressure cylinder side rapid cooling intake pipe enters the intermediate-pressure cylinder side rapid cooling intake pipe through the preheating circulation pipe. After merging with the cooling medium in the intermediate-pressure cylinder side rapid cooling intake pipe, it returns to the intake end of the pressurizing blower through the intermediate-pressure cylinder side rapid cooling return pipe and the blower recirculation valve, forming a circulating heating circuit. The preheating circulation valve is closed after the temperature of the high-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the high-pressure cylinder and the temperature of the intermediate-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the intermediate-pressure cylinder, thus ending the preheating process.

[0017] It should be further explained that the flow rate of the cooling medium returning to the inlet of the pressurizing blower is adjusted by the blower recirculation valve to control the circulation flow rate during the preheating process.

[0018] It should be further explained that the specific steps of the cooling medium circulation in step S3 are as follows: Open the intake valve, the first isolation valve, the second isolation valve, the third isolation valve, the high-pressure cylinder side rapid cooling intake valve, the medium-pressure cylinder side rapid cooling intake valve, the two low-pressure cylinder side rapid cooling intake valves, the two high-pressure cylinder side rapid cooling return valves, the two medium-pressure cylinder side rapid cooling return valves, and the two low-pressure cylinder side rapid cooling return valves; The pressurized fan is started to draw in and output cooling medium. The first part of the cooling medium output by the pressurized fan enters the temperature chamber heater sequentially through the fan outlet pipe, electric heater, and heater outlet pipe. During this process, the cooling medium is heated. After the heated cooling medium flows out of the temperature chamber heater, part of it passes through the first air supply pipe and the first heat exchanger, and then enters the exhaust side of the high-pressure cylinder through the high-pressure cylinder side rapid cooling inlet pipe. It flows out from the high-pressure cylinder inlet side, and returns to the return end of the temperature chamber heater through the high-pressure cylinder side rapid cooling return pipe and two high-pressure cylinder side rapid cooling return valves. The other part of the heated cooling medium passes through the second air supply pipe and the second heat exchanger, and then enters the exhaust side of the intermediate-pressure cylinder through the intermediate-pressure cylinder side rapid cooling inlet pipe. It flows out from the intermediate-pressure cylinder inlet side, and returns to the return end of the temperature chamber heater through the intermediate-pressure cylinder side rapid cooling return pipe and two intermediate-pressure cylinder side rapid cooling return valves. The second part of the cooling medium output by the pressurized fan enters the heater of the third electric temperature box through the third air supply pipe and is heated. Then, it enters the exhaust side of the two low-pressure cylinders through the two low-pressure cylinder side rapid cooling air inlet pipes and the two low-pressure cylinder side rapid cooling air inlet valves respectively. It flows out from the air inlet side of the low-pressure cylinder and returns to the return end of the temperature box heater through the two low-pressure cylinder side rapid cooling return air pipes and the two low-pressure cylinder side rapid cooling return air valves.

[0019] It should be further explained that, in step S3, the specific operation of adjusting the intake temperature of the cooling medium for each cylinder based on the relationship between the real-time temperature gradient and the corresponding initial temperature gradient is as follows: When the real-time temperature gradient of the high-pressure cylinder is greater than or equal to the initial temperature gradient of the high-pressure cylinder minus the preset temperature difference, the temperature of the cooling medium entering the high-pressure cylinder is maintained; when the real-time temperature gradient of the high-pressure cylinder is less than the initial temperature gradient of the high-pressure cylinder minus the preset temperature difference, the opening of the high-pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurizing fan that directly enters the fast cooling intake pipe on the high-pressure cylinder side, thereby reducing the temperature of the cooling medium entering the high-pressure cylinder. When the real-time temperature gradient of the intermediate pressure cylinder is greater than or equal to the initial temperature gradient of the intermediate pressure cylinder minus the preset temperature difference, the temperature of the cooling medium entering the intermediate pressure cylinder is maintained; when the real-time temperature gradient of the intermediate pressure cylinder is less than the initial temperature gradient of the intermediate pressure cylinder minus the preset temperature difference, the opening of the intermediate pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurized fan directly entering the fast cooling intake pipe on the intermediate pressure cylinder side, thereby reducing the temperature of the cooling medium entering the intermediate pressure cylinder. When the real-time temperature gradient of both low-pressure cylinders is greater than or equal to the initial temperature gradient minus the preset temperature difference value of the low-pressure cylinder, the temperature of the cooling medium entering the low-pressure cylinder is maintained; when the real-time temperature gradient of any low-pressure cylinder is less than the initial temperature gradient minus the preset temperature difference value of the low-pressure cylinder, the heating power of the heater of the third electric temperature box is reduced, and the temperature of the cooling medium entering the low-pressure cylinder is reduced.

[0020] It should be further noted that the preset temperature difference is 5-10℃.

[0021] It should be further noted that step S3 also includes: During the cooling medium circulation process, the opening of the fast cooling intake valve on the high-pressure cylinder side and the fast cooling intake valve on the intermediate-pressure cylinder side are adjusted to make the fast cooling return pressure on the high-pressure cylinder side greater than that on the intermediate-pressure cylinder side; and the pressure balance valve is opened to make the fast cooling return pressure on the intermediate-pressure cylinder side less than that on the low-pressure cylinder side.

[0022] It should be further noted that in step S4, the turning temperature threshold is ≤150℃.

[0023] It should be further explained that the specific operation to stop rapid cooling in step S4 is as follows: Turn off the pressurizing fan, close the high-pressure cylinder side rapid cooling intake valve, the medium-pressure cylinder side rapid cooling intake valve and the two low-pressure cylinder side rapid cooling intake valves, and close the first isolation valve, the second isolation valve and the third isolation valve.

[0024] It should be further noted that in step S4, after the rapid cooling is stopped, the turbine body continues to maintain the turning state until the internal metal temperature of each cylinder is uniform.

[0025] As can be seen from the above technical solutions, this application has the following advantages: 1. The counter-current rapid cooling system for steam turbines provided in this application achieves independent and controllable counter-current cooling of each cylinder by introducing the cooling medium from the exhaust side of each cylinder and drawing it out from the inlet side. This is achieved through a specific structure in which the pressurized fan, temperature box heater, electric heater, first heat exchanger, second heat exchanger, and third electric temperature box heater are connected to the exhaust side of the high-pressure cylinder, the exhaust side of the intermediate-pressure cylinder, and the exhaust side of the two low-pressure cylinders via independent pipelines. This effectively avoids the thermal shock and temperature gradient amplification problems caused by the cooling medium first contacting the high-temperature inlet side in existing co-current cooling methods, significantly reduces the peak thermal stress during the cooling process, ensures the structural integrity of key components of the steam turbine, and greatly shortens the cooling cycle.

[0026] 2. This application provides cooling media to the high-pressure cylinder, the medium-pressure cylinder, and the two low-pressure cylinders independently through a first heat exchanger, a second heat exchanger, and a third electric temperature box heater. Each cylinder has its own independent intake and return pipes connected to the exhaust and intake sides of the cylinders. This allows for setting and adjusting the intake temperature according to the different exhaust side metal wall temperatures of each cylinder after shutdown, achieving precise and independent control of the cooling process of each cylinder. This avoids mutual interference caused by temperature differences between cylinders, ensuring the uniformity and controllability of cooling. This overcomes the shortcomings of existing technologies where a single heating source or a unified air supply path cannot match the different initial intake temperatures of each cylinder.

[0027] 3. The counter-current rapid cooling method for steam turbines provided in this application uses the exhaust side metal wall temperature of each cylinder as the initial inlet temperature for the rapid cooling device of that cylinder, and uses the difference between the highest and lowest temperature points of each cylinder as the initial temperature gradient during natural cooling of that cylinder. This ensures that the temperature of the cooling medium entering the cylinder matches the metal temperature of the lowest temperature region within the cylinder, solving the problem in existing methods where improper selection of the inlet temperature exacerbates the internal temperature gradient of the cylinder, and avoiding additional thermal stress caused by excessively low or high cooling medium temperatures from the source.

[0028] 4. This application obtains the highest and lowest temperature points of each cylinder block, calculates the real-time temperature gradient, and adjusts the intake temperature of the cooling medium for each cylinder block according to the relationship between the real-time temperature gradient and the corresponding initial temperature gradient. This overcomes the shortcomings of existing methods that cannot adjust the intake temperature according to the real-time temperature state of the cylinder block, which leads to uncontrolled thermal stress. It achieves dynamic closed-loop control of thermal stress during the cooling process, ensuring that the temperature gradient is always within a safe range throughout the cooling process.

[0029] 5. This application utilizes a counter-current circulation of the cooling medium within the turbine body, where the flow direction is opposite to that of the normal operating medium. Furthermore, it stops rapid cooling when the highest temperature inside all cylinders drops to a preset turning gear temperature threshold. This ensures that the entire cooling process targets the highest temperature point on the cylinder inlet side as the final cooling objective. While maintaining controllable thermal stress, it prioritizes reducing the temperature in high-temperature regions and terminates the process promptly upon reaching a safety threshold. Compared to existing methods, this significantly improves cooling efficiency and reduces energy consumption, while avoiding over-cooling or uneven cooling. Attached Figure Description

[0030] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a turbine counter-current rapid cooling system in one embodiment of this application.

[0032] Figure 2 This is a flowchart of a method for rapid counter-current cooling of a steam turbine in one embodiment of this application.

[0033] In the diagram, 1-high pressure cylinder, 2-medium pressure cylinder, 3-low pressure cylinder, 4-pressurizing blower, 5-electric heater, 6-temperature box heater, 7-first heat exchanger, 8-second heat exchanger, 9-third electric temperature box heater. Detailed Implementation

[0034] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The following describes in detail the counter-current rapid cooling method for steam turbines according to this application. Specific details, such as particular system structures and technologies, are presented for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0036] In the counter-current rapid cooling method for steam turbines disclosed in this application, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0037] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0038] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0040] The turbine counter-current rapid cooling method provided in this application embodiment is executed by computer equipment, and correspondingly, the turbine counter-current rapid cooling system operates in the computer equipment.

[0041] Figure 1 This is a schematic diagram of the counter-current rapid cooling system for a steam turbine in one embodiment of this application, as shown below. Figure 1 As shown, the turbine counter-current rapid cooling system includes the turbine body and a rapid cooling device; The turbine body includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2, and two low-pressure cylinders 3. The exhaust side of the high-pressure cylinder 1 is connected to the inlet side of the intermediate-pressure cylinder 2 through a high-pressure exhaust pipe. The exhaust side of the intermediate-pressure cylinder 2 is connected to the inlet side of the two low-pressure cylinders 3 through two intermediate-pressure exhaust pipes respectively. The rapid cooling device includes a pressurizing fan 4, an electric heater 5, a temperature chamber heater 6, a first heat exchanger 7, a second heat exchanger 8, and a third electric temperature chamber heater 9. The air outlet of the pressurizing fan 4 is connected to the air inlet of the electric heater 5 through a fan outlet pipe. The air outlet of the electric heater 5 is connected to the air inlet of the temperature chamber heater 6 through a heater outlet pipe. The air outlet of the temperature chamber heater 6 is connected to the air inlet of the first heat exchanger 7 through a first air supply pipe. The air outlet of the temperature chamber heater 6 is connected to the air inlet of the second heat exchanger 8 through a second air supply pipe. The outlet of the first heat exchanger 7 is connected to the exhaust side of the high-pressure cylinder 1 through the fast cooling inlet pipe on the high-pressure cylinder side, and the outlet of the second heat exchanger 8 is connected to the exhaust side of the intermediate-pressure cylinder 2 through the fast cooling inlet pipe on the intermediate-pressure cylinder side. The outlet of the pressurizing blower 4 is connected to the inlet of the third electric temperature box heater 9 through the third air supply pipe. The outlet of the third electric temperature box heater 9 is connected to the exhaust side of the two low-pressure cylinders 3 through the low-pressure cylinder side fast cooling air inlet pipe respectively. The steam inlet side of the high-pressure cylinder 1 is connected to the return gas end of the temperature chamber heater 6 through the high-pressure cylinder side rapid cooling return gas pipe. The steam inlet side of the intermediate-pressure cylinder 2 is connected to the return gas end of the temperature chamber heater 6 through the intermediate-pressure cylinder side rapid cooling return gas pipe. The steam inlet sides of the two low-pressure cylinders 3 are respectively connected to the return gas end of the temperature chamber heater 6 through two low-pressure cylinder side rapid cooling return gas pipes.

[0042] The rapid cooling device is constructed by connecting the pressurizing fan, the incubator heater, the electric heater, the first heat exchanger, the second heat exchanger, and the third electric incubator heater to the exhaust side of the high-pressure cylinder via the rapid cooling inlet pipe on the high-pressure cylinder side, to the exhaust side of the intermediate-pressure cylinder via the rapid cooling inlet pipe on the intermediate-pressure cylinder side, and to the exhaust side of the two low-pressure cylinders via the rapid cooling inlet pipes on the two low-pressure cylinder sides. Simultaneously, the inlet side of the high-pressure cylinder is connected via the rapid cooling return pipe on the high-pressure cylinder side, the inlet side of the intermediate-pressure cylinder is connected via the rapid cooling return pipe on the intermediate-pressure cylinder side, and the inlet sides of the two low-pressure cylinders are connected via the rapid cooling return pipes on the two low-pressure cylinder sides. By connecting the return gas end of the heat exchanger heater, the overall flow direction of the cooling medium within the turbine body is completely opposite to that of the normal operating medium. As a result, during the cooling process, the cooling medium first enters the cylinder from the lower temperature exhaust side and gradually flows to the higher temperature inlet side, where it is gradually heated. This avoids the rapid temperature drop caused by the high temperature inlet side directly contacting the cooling medium in co-current cooling, achieving a gradual decrease in the internal temperature gradient of the cylinder, significantly reducing the peak thermal stress, and ensuring that each cylinder can independently obtain the cooling medium tailored to its own exhaust side temperature, effectively shortening the cooling cycle.

[0043] In some specific embodiments, a high-pressure cylinder-side rapid cooling intake pipe is provided with a high-pressure cylinder-side rapid cooling intake valve, a medium-pressure cylinder-side rapid cooling intake pipe is provided with a medium-pressure cylinder-side rapid cooling intake valve, a low-pressure cylinder-side rapid cooling intake pipe is provided with a low-pressure cylinder-side rapid cooling intake valve corresponding to the low-pressure cylinder 3, a high-pressure cylinder-side rapid cooling return pipe is provided with two parallel high-pressure cylinder-side rapid cooling return valves, a medium-pressure cylinder-side rapid cooling return pipe is provided with two parallel medium-pressure cylinder-side rapid cooling return valves, and two low-pressure cylinder-side rapid cooling return pipes are respectively provided with corresponding low-pressure cylinder-side rapid cooling return valves. A high-pressure cylinder-side rapid cooling intake pipe is equipped with a high-pressure cylinder-side rapid cooling intake temperature sensor, a high-pressure cylinder-side rapid cooling return pipe is equipped with a high-pressure cylinder-side rapid cooling return pressure sensor, an intermediate-pressure cylinder-side rapid cooling intake pipe is equipped with an intermediate-pressure cylinder-side rapid cooling intake temperature sensor, an intermediate-pressure cylinder-side rapid cooling return pipe is equipped with an intermediate-pressure cylinder-side rapid cooling return pressure sensor, a low-pressure cylinder-side rapid cooling intake pipe is equipped with a low-pressure cylinder-side rapid cooling intake temperature sensor, and two low-pressure cylinder-side rapid cooling return pipes are each equipped with a corresponding low-pressure cylinder-side rapid cooling return pressure sensor.

[0044] The above-mentioned structure allows operators to independently control the on / off state and flow rate of each intake and return pipe, and monitor the intake temperature and return pressure of each cylinder in real time. This enables precise control of the cooling medium entering and leaving each cylinder, ensuring pressure balance and temperature matching between cylinders during the counter-current cooling process, and preventing backflow or local overcooling caused by pressure or temperature imbalance.

[0045] In some specific embodiments, the outlet of the pressurized blower 4 is connected to the rapid cooling intake pipe on the high-pressure cylinder side and the rapid cooling intake pipe on the medium-pressure cylinder side through a mixing pipe. The section where the mixing pipe connects to the high-pressure cylinder side rapid cooling intake pipe is equipped with a high-pressure cylinder side rapid cooling mixing regulating valve, and the section where the mixing pipe connects to the medium-pressure cylinder side high-pressure cylinder side rapid cooling intake pipe is equipped with a medium-pressure cylinder side rapid cooling mixing regulating valve.

[0046] In some specific embodiments, a high-pressure reverse heating valve is also provided on the high-pressure cylinder side rapid cooling return pipe; and a medium-pressure cylinder side rapid cooling return flow regulating valve is also provided on the medium-pressure cylinder side rapid cooling return pipe.

[0047] Through the above structural design, the system can mix the unheated cooling medium output by the pressurized blower into the fresh cooling medium that is about to enter the cylinder in a certain proportion, thereby flexibly adjusting the intake air temperature. Furthermore, by adjusting the return air flow, the cooling rate can be further controlled, thus achieving fine adjustment of the intake air temperature of the high-pressure cylinder and the intermediate-pressure cylinder.

[0048] In some specific embodiments, a high-pressure reverse heating intake valve is also provided on the high-pressure cylinder side rapid cooling intake pipe, a medium-pressure reverse heating intake valve is also provided on the medium-pressure cylinder side rapid cooling intake pipe, and a low-pressure heater front valve is also provided on the low-pressure cylinder side rapid cooling intake pipe.

[0049] Through the above structural design, the system can selectively bypass a portion of the cooling medium that has already been heated by the temperature chamber heater to the intake pipe of the corresponding cylinder according to the real-time temperature requirements of each cylinder during the cooling process. This allows for supplementary heating or insulation of specific cylinders using the existing high-temperature medium without needing to start the first heat exchanger, the second heat exchanger, or the third electric temperature chamber heater. This avoids intake temperature fluctuations caused by a single heating source failure or adjustment lag, and further enhances the independent controllability and response speed of the intake temperature of each cylinder during the counter-current cooling process.

[0050] In some specific embodiments, the turbine counter-current rapid cooling system also includes a preheating circulation pipe and a pressure balance pipe. The preheating circulation pipe is connected to the high-pressure cylinder side rapid cooling inlet pipe and the intermediate-pressure cylinder side rapid cooling inlet pipe. The pressure balance pipe is connected to the intermediate-pressure cylinder side rapid cooling return pipe and two low-pressure cylinder side rapid cooling return pipes. A preheating circulation valve is provided on the preheating circulation pipe, and a pressure balance valve is provided on the pressure balance pipe. The high-pressure cylinder side rapid cooling return pipe is also equipped with a high-pressure cylinder side rapid cooling return gas flow sensor and a high-pressure cylinder side rapid cooling return gas pressure sensor. The intermediate-pressure cylinder side rapid cooling return pipe is also equipped with an intermediate-pressure cylinder side rapid cooling return gas flow sensor and an intermediate-pressure cylinder side rapid cooling return gas pressure sensor. The two low-pressure cylinder side rapid cooling return pipes are respectively equipped with corresponding low-pressure cylinder side rapid cooling return gas temperature sensors.

[0051] By setting up the aforementioned valves and sensors, the system can rapidly preheat the high-pressure and medium-pressure cylinder-side rapid cooling intake pipes using the preheating circulation pipes before cooling start-up. During the cooling process, the pressure difference between the medium-pressure cylinder-side rapid cooling return pipes and the low-pressure cylinder-side rapid cooling return pipes is adjusted through the pressure balance pipes, thereby ensuring smooth flow of the medium and reasonable pressure distribution in the return pipes of each cylinder. With the addition of new flow, pressure, and temperature sensors, the return gas status of each cylinder can be monitored more comprehensively, providing stable return gas channel conditions for counter-current cooling.

[0052] In some specific embodiments, an air inlet valve is provided on the air outlet pipe of the blower, a blower exhaust valve is provided at the outlet of the pressurized blower 4, a heater exhaust valve is provided on the air outlet pipe of the heater, a first isolation valve is provided on the first air supply pipe, a second isolation valve is provided on the second air supply pipe, and a third isolation valve is provided on the third air supply pipe. The medium-pressure cylinder side rapid cooling return pipe is connected to the air inlet of the pressurizing blower through a circulation pipe, and the circulation pipe is equipped with a blower recirculation valve.

[0053] By setting the valves mentioned above, the system can form an internal circulation loop by opening the fan recirculation valve and the corresponding isolation valve before startup, preheating and venting the body of the rapid cooling device and the air supply pipeline. This avoids thermal shock caused by low-temperature pipelines or residual condensate directly entering the cylinder. After cooling is completed, the remaining medium in the system is released through the vent valve, thereby significantly improving the safety and temperature uniformity of the countercurrent cooling process during startup and shutdown.

[0054] In some specific embodiments, a control box is installed on the rapid cooling device. Each temperature sensor, pressure sensor, and valve in the turbine counter-current rapid cooling system is electrically connected to the control box. The control box includes a processor, which is configured to control the operation of each valve based on the temperature and pressure values ​​collected by each temperature and pressure sensor.

[0055] With the above structural design, the entire cooling process can automatically adjust the opening of each valve based on parameters such as the cylinder intake temperature and return pressure monitored in real time. It can maintain the matching relationship between the intake temperature of each cylinder and the metal wall temperature on the exhaust side without manual intervention, and correct pressure fluctuations caused by cylinder temperature changes in real time. This achieves fully automatic closed-loop control of counter-current cooling, which greatly reduces the difficulty of operation and the risk of human error.

[0056] In some specific embodiments, the control box also includes a memory and a drive circuit.

[0057] Figure 2 This is a flowchart of a counter-current rapid cooling method for a steam turbine according to an embodiment of this application. Wherein, Figure 2The implementing entity is a steam turbine counter-flow rapid cooling system. This steam turbine counter-flow rapid cooling method belongs to the same inventive concept as the steam turbine counter-flow rapid cooling systems in the above embodiments. Details not described in detail in the embodiments of the steam turbine counter-flow rapid cooling method can be found in the embodiments of the steam turbine counter-flow rapid cooling system described above. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0058] like Figure 2 As shown, the counter-current rapid cooling method for the steam turbine includes: Step S1: After the turbine body is shut down and the turning gear is engaged, the temperature of the metal wall on the exhaust side of each cylinder and the highest and lowest temperature points of each cylinder are collected. The exhaust side metal wall temperature of each cylinder is taken as the initial intake temperature for the cylinder's rapid cooling device to be put into operation, and the difference between the highest and lowest temperature points is taken as the initial temperature gradient when the cylinder is naturally cooled. The cylinder body includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2, and two low-pressure cylinders 3.

[0059] Through the above steps, the system has already grasped the true temperature distribution characteristics of each cylinder at the moment of shutdown before any cooling medium is introduced into the cylinder. This provides accurate reference data for subsequent cooling medium temperature setting and thermal stress control, avoiding excessive temperature gradients in the early stage of cooling due to blindly selecting intake temperature, and ensuring the safety of the counter-current cooling process from the source.

[0060] Step S2: Start the rapid cooling device. The cooling medium is drawn in by the pressurized fan 4 and then sequentially delivered to the fan outlet pipe, electric heater 5, heater outlet pipe, and temperature box heater 6 to heat the cooling medium. The high-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the high-pressure cylinder 1 using a heated cooling medium, and the intermediate-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the intermediate-pressure cylinder 2.

[0061] Through the above steps, the temperature of the inner wall of the intake pipe that comes into contact with the cooling medium has risen to the same level as the temperature of the metal wall on the exhaust side of the cylinder before the cooling medium officially enters the high-pressure cylinder and the intermediate-pressure cylinder. This avoids unnecessary cooling of the medium or thermal stress on the pipe itself when the low-temperature pipe wall is initially introduced. It also prevents condensate that may exist on the inner wall of the pipe from being carried into the cylinder, providing stable and uniform intake conditions for counter-current cooling.

[0062] In some specific embodiments, the cooling medium is external air or steam.

[0063] By limiting the cooling medium to external air or steam, this method allows for flexible selection of the cooling medium based on the actual medium supply conditions at the turbine site. When using external air, open-loop cooling can be achieved using cost-free air sources in the atmosphere. When using steam, closed-loop cooling can be achieved using the power plant's own auxiliary steam system, avoiding the oxidation risks that air may bring. Thus, without changing the core counter-current cooling process, two safe and reliable medium options are provided for turbines with different operating conditions and materials, effectively expanding the applicability and field adaptability of this rapid cooling method.

[0064] In some specific embodiments, step S2 specifically includes: Open the first isolation valve, the second isolation valve, the preheating circulation valve, and the fan recirculation valve; close the high-pressure cylinder side rapid cooling intake valve and the medium-pressure cylinder side rapid cooling intake valve. The pressurizing fan 4 is started to draw in the cooling medium. The cooling medium passes through the fan outlet pipe, the electric heater 5, and the heater outlet pipe in sequence to enter the temperature chamber heater 6. During the process, the cooling medium is heated. After the heated cooling medium flows out of the temperature box heater 6, part of it is sent to the high-pressure cylinder side rapid cooling intake pipe through the first air supply pipe and the first heat exchanger 7, and the other part is sent to the medium-pressure cylinder side rapid cooling intake pipe through the second air supply pipe and the second heat exchanger 8. The cooling medium sent to the high-pressure cylinder side rapid cooling intake pipe enters the medium-pressure cylinder side rapid cooling intake pipe through the preheating circulation pipe. After merging with the cooling medium in the medium-pressure cylinder side rapid cooling intake pipe, it returns to the intake end of the pressurizing blower 4 through the medium-pressure cylinder side rapid cooling return pipe and the blower recirculation valve, forming a circulating heating circuit. The preheating circulation valve is closed and the preheating ends when the temperature of the high-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the high-pressure cylinder 1 and the temperature of the medium-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the medium-pressure cylinder 2.

[0065] Through the above operations, the high-pressure and medium-pressure cylinder-side rapid cooling intake pipelines can be uniformly heated to the target temperature through internal circulation before officially supplying air to the cylinder block. This avoids the risk of the initial cooling medium temperature dropping or condensate being carried into the cylinder block due to excessively low pipeline temperature. At the same time, the automatic closed-loop control of the preheating process is achieved by using the fan recirculation valve and the preheating circulation valve, which significantly improves the safety and temperature stability of the counter-current cooling start-up phase.

[0066] In some specific embodiments, the flow rate of the cooling medium returning to the inlet of the pressurizing fan 4 is adjusted by the fan recirculation valve to control the circulation flow rate during the preheating process.

[0067] Through the above operations, the flow rate of the circulating medium can be dynamically adjusted according to the actual temperature rise rate of the high-pressure cylinder-side rapid cooling intake pipe and the medium-pressure cylinder-side rapid cooling intake pipe during the preheating stage. When the pipe temperature is significantly different from the target temperature, a larger circulation flow rate is used to accelerate the temperature rise. When the temperature approaches the target temperature, the circulation flow rate is reduced to prevent overheating. This achieves controllability and precision in the preheating process, avoiding problems such as excessively long preheating time or temperature overshoot caused by a fixed flow rate. It effectively improves preheating efficiency and ensures precise matching between the intake pipe temperature and the cylinder block's initial intake temperature.

[0068] In step S3, the cooling medium in the temperature chamber heater 6 is sent to the first heat exchanger 7 through the first air supply pipe and to the second heat exchanger 8 through the second air supply pipe. At the same time, the pressurized fan 4 sends the cooling medium to the third electric temperature chamber heater 9 through the third air supply pipe to circulate the cooling medium. The cooling medium fed into the first heat exchanger 7 enters the exhaust side of the high-pressure cylinder 1 through the high-pressure cylinder side rapid cooling inlet pipe, flows out from the inlet side of the high-pressure cylinder 1, and returns to the return end of the temperature box heater 6 through the high-pressure cylinder side rapid cooling return pipe. The cooling medium fed into the second heat exchanger 8 is sent to the exhaust side of the intermediate pressure cylinder 2 through the rapid cooling inlet pipe on the intermediate pressure cylinder side, flows out from the inlet side of the intermediate pressure cylinder 2, and returns to the return end of the temperature box heater 6 through the rapid cooling return pipe on the intermediate pressure cylinder side. The cooling medium fed into the third electric temperature box heater 9 is heated by the third electric temperature box heater 9 and then sent to the exhaust side of the two low-pressure cylinders 3 through the two low-pressure cylinder side rapid cooling intake pipes respectively. It flows out from the intake side of the low-pressure cylinder 3 and then returns to the return end of the temperature box heater 6 through the two low-pressure cylinder side rapid cooling return pipes respectively. The heating power of the third electric temperature box heater 9 is set to make the temperature of the cooling medium after passing through the third electric temperature box heater 9 equal to the lower value of the initial intake temperature of the two low-pressure cylinders. The flow direction of the cooling medium inside the turbine body is opposite to the flow direction of the normal operating medium in the turbine. During the cooling medium circulation process, the highest and lowest temperature points of each cylinder are obtained respectively. The difference between the highest and lowest temperature points of each cylinder is used as the real-time temperature gradient of that cylinder. The intake temperature of the cooling medium of each cylinder is adjusted according to the relationship between the real-time temperature gradient of each cylinder and the corresponding initial temperature gradient.

[0069] Through the above operations, counter-current cooling can dynamically reduce the intake temperature independently within each cylinder without exceeding the safety boundary of natural cooling thermal stress. This maximizes the cooling rate while ensuring that the metal parts are not damaged. Furthermore, by using the lower initial intake temperature of the two cylinders to supply air uniformly through the third electric temperature box heater, the problem of one cylinder being overcooled and the other cylinder being undercooled due to temperature differences between the two low-pressure cylinders is avoided.

[0070] In some specific embodiments, the specific steps of cooling medium circulation are as follows: Open the intake valve, the first isolation valve, the second isolation valve, the third isolation valve, the high-pressure cylinder side rapid cooling intake valve, the medium-pressure cylinder side rapid cooling intake valve, the two low-pressure cylinder side rapid cooling intake valves, the two high-pressure cylinder side rapid cooling return valves, the two medium-pressure cylinder side rapid cooling return valves, and the two low-pressure cylinder side rapid cooling return valves; The pressurized blower 4 is started to draw in and output cooling medium. The first part of the cooling medium output by the pressurized blower 4 enters the temperature chamber heater 6 through the blower outlet pipe, electric heater 5, and heater outlet pipe in sequence. During the process, the cooling medium is heated. After the heated cooling medium flows out of the temperature chamber heater 6, part of it enters the exhaust side of the high-pressure cylinder 1 through the first air supply pipe and the first heat exchanger 7, and flows out from the inlet side of the high-pressure cylinder 1. It then returns to the return end of the temperature chamber heater 6 through the high-pressure cylinder side rapid cooling return pipe and two high-pressure cylinder side rapid cooling return valves. The other part of the heated cooling medium enters the exhaust side of the medium-pressure cylinder 2 through the second air supply pipe and the second heat exchanger 8 through the intermediate-pressure cylinder side rapid cooling inlet pipe, and flows out from the inlet side of the intermediate-pressure cylinder 2. It then returns to the return end of the temperature chamber heater 6 through the intermediate-pressure cylinder side rapid cooling return pipe and two intermediate-pressure cylinder side rapid cooling return valves. The second part of the cooling medium output by the pressurizing fan 4 enters the third electric temperature box heater 9 through the third air supply pipe for heating, and then enters the exhaust side of the two low-pressure cylinders 3 through the two low-pressure cylinder side rapid cooling air inlet pipes and the two low-pressure cylinder side rapid cooling air inlet valves respectively. It flows out from the air inlet side of the low-pressure cylinder 3 and returns to the return end of the temperature box heater 6 through the two low-pressure cylinder side rapid cooling return air pipes and the two low-pressure cylinder side rapid cooling return air valves.

[0071] Through the above operations, the cooling medium circulation channels of the three cylinders are established synchronously and independently at the same time. The intake temperature and return path of each cylinder are controlled by its dedicated heat exchanger or heater, thus ensuring that there is no medium crossflow or pressure interference between the cylinders during the counter-current cooling process. Furthermore, since all return gas returns to the return gas end of the temperature box heater, partial recovery and utilization of the return gas heat is achieved, effectively reducing the energy consumption of the entire cooling process.

[0072] In some specific embodiments, the specific operation of adjusting the intake temperature of the cooling medium for each cylinder based on the relationship between the real-time temperature gradient of each cylinder and the corresponding initial temperature gradient is as follows: When the real-time temperature gradient of high-pressure cylinder 1 is greater than or equal to the initial temperature gradient of high-pressure cylinder 1 minus the preset temperature difference, the temperature of the cooling medium entering high-pressure cylinder 1 is maintained; when the real-time temperature gradient of high-pressure cylinder 1 is less than the initial temperature gradient of high-pressure cylinder 1 minus the preset temperature difference, the opening of the high-pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurizing fan 4 that directly enters the fast cooling intake pipe on the high-pressure cylinder side, thereby reducing the temperature of the cooling medium entering high-pressure cylinder 1. When the real-time temperature gradient of the intermediate pressure cylinder 2 is greater than or equal to the initial temperature gradient of the intermediate pressure cylinder 2 minus the preset temperature difference, the temperature of the cooling medium entering the intermediate pressure cylinder 2 is maintained; when the real-time temperature gradient of the intermediate pressure cylinder 2 is less than the initial temperature gradient of the intermediate pressure cylinder 2 minus the preset temperature difference, the opening of the intermediate pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurizing fan 4 that directly enters the rapid cooling intake pipe on the intermediate pressure cylinder side, thereby reducing the temperature of the cooling medium entering the intermediate pressure cylinder 2. When the real-time temperature gradient of both low-pressure cylinders 3 is greater than or equal to the initial temperature gradient of the low-pressure cylinder 3 minus the preset temperature difference, the temperature of the cooling medium entering the low-pressure cylinder is maintained; when the real-time temperature gradient of any low-pressure cylinder 3 is less than the initial temperature gradient of the low-pressure cylinder 3 minus the preset temperature difference, the heating power of the third electric temperature box heater 9 is reduced, and the temperature of the cooling medium entering the low-pressure cylinder 3 is reduced.

[0073] Through the above operations, the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder can independently and dynamically adjust their intake temperature based on their own real-time temperature gradient changes. The adjustment methods are tailored to the structural characteristics of different cylinder blocks, using mixed-air regulation for high pressure, intermediate pressure, or power regulation for low pressure. This achieves precise control of the thermal stress of each cylinder block and avoids control failure problems caused by a uniform adjustment method being unable to adapt to the thermal response characteristics of different cylinder blocks.

[0074] In some specific embodiments, the preset temperature difference value is 5-10℃.

[0075] By specifically limiting the preset temperature difference value to a range of 5-10℃, the threshold for determining whether to reduce the intake temperature of the cooling medium has a clear numerical range. This range is neither too small, which would cause the system to frequently make unnecessary adjustments, thereby increasing the wear of valves and heaters, nor too large, which would cause the real-time temperature gradient to be significantly lower than the initial temperature gradient without triggering cooling, thus missing the opportunity to optimize the cooling rate. Therefore, while ensuring that the thermal stress is always within a safe range, a reasonable and engineering-verified temperature difference benchmark is provided for the logical judgment of the control system, effectively balancing the relationship between cooling rate and control stability.

[0076] In some specific embodiments, step S3 further includes: During the cooling medium circulation process, the opening of the fast cooling intake valve on the high-pressure cylinder side and the fast cooling intake valve on the intermediate-pressure cylinder side are adjusted to make the fast cooling return pressure on the high-pressure cylinder side greater than that on the intermediate-pressure cylinder side; and the pressure balance valve is opened to make the fast cooling return pressure on the intermediate-pressure cylinder side less than that on the low-pressure cylinder side.

[0077] Through the above operations, a specific pressure gradient relationship is established between the return gas pipelines of the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder during the counter-current cooling process. That is, the rapid cooling return gas pressure on the high-pressure cylinder side is higher than that on the intermediate-pressure cylinder side, and the rapid cooling return gas pressure on the intermediate-pressure cylinder side is lower than that on the low-pressure cylinder side. This pressure distribution can effectively prevent the return gas from the low-pressure cylinder from flowing back into the intermediate-pressure cylinder or the return gas from the intermediate-pressure cylinder from flowing back into the high-pressure cylinder. At the same time, by using a pressure balance pipe to connect the rapid cooling return gas pipeline on the intermediate-pressure cylinder side with the rapid cooling return gas pipeline on the low-pressure cylinder side, the pressure difference between the two can be stabilized. This ensures that the flow direction of the medium in the return gas pipeline of each cylinder is always consistent with the design direction, avoiding the problem of cooling medium crossflow between cylinders or local cooling failure caused by pressure turbulence, and significantly improving the operational reliability of the counter-current cooling system.

[0078] Step S4: When the highest temperature inside all cylinders drops to the preset turning temperature threshold, stop rapid cooling.

[0079] Through the above steps, the cooling process is prevented from ending prematurely due to one cylinder reaching the threshold, thus preventing other cylinders from not being cooled to the required temperature. It also avoids premature shutdown due to some cylinders still being above the threshold, which would prolong the subsequent natural cooling time. This ensures that the entire turbine can enter the turning gear state at a uniform temperature level after shutdown, preventing residual thermal stress caused by inconsistent cooling completion times between cylinders. Furthermore, since the threshold is set as the turning gear temperature, the turning gear can be maintained directly after shutdown without a second restart, further improving operational convenience and safety.

[0080] In some specific embodiments, the turning temperature threshold is ≤150℃.

[0081] By specifically limiting the turning gear temperature threshold to no more than 150°C, rapid cooling is only stopped when the highest temperature inside all cylinders drops to 150°C or below. This temperature value is the upper limit of the safe turning gear shutdown temperature commonly used in the steam turbine industry. Below this temperature, the metal materials of the steam turbine rotor and cylinders have sufficient toughness and thermal stress resistance, allowing for safe stopping of turning gear or subsequent maintenance work. This provides a clear and engineering-based numerical standard for the termination conditions of the rapid cooling method, avoiding the safety risks caused by stopping cooling when there is still significant thermal stress inside the cylinder due to an excessively high threshold setting, and also avoiding unnecessary over-cooling due to an excessively low threshold setting, which would waste energy and time.

[0082] In some specific embodiments, the specific operation to stop rapid cooling is as follows: Turn off the pressurizing fan 4, close the high-pressure cylinder side rapid cooling intake valve, the medium-pressure cylinder side rapid cooling intake valve and the two low-pressure cylinder side rapid cooling intake valves, and close the first isolation valve, the second isolation valve and the third isolation valve.

[0083] Through the above operations, it can be ensured that the residual cooling medium in the system after the pressurizing fan stops will not be trapped in a cylinder or pipeline due to improper valve closing sequence, resulting in local overcooling or pressure shock. At the same time, closing the intake valve first and then the isolation valve can avoid abnormal high pressure caused by the isolation valve closing prematurely, which would prevent the medium in the pipeline between the intake valve and the isolation valve from being released. Thus, the shutdown process of the reverse flow cooling system is safe, orderly and reliable.

[0084] In some specific embodiments, after the rapid cooling is stopped, the turbine body continues to maintain a turning state until the internal metal temperature of each cylinder is uniform.

[0085] Through the above operations, even though the cooling medium has stopped flowing in, the turbine rotor continues to rotate slowly under the drive of the turning gear. This rotation promotes the natural convection and conduction of residual heat inside each cylinder, which further eliminates the residual temperature difference between the steam inlet and exhaust sides of the cylinder and between the rotor and the cylinder. This avoids subsequent thermal stress or rotor bending deformation caused by the continued presence of local temperature differences after cooling stops. At the same time, maintaining the turning gear state until the temperature is uniform also ensures that the turbine can safely enter the next startup or maintenance process at any time, improving the integrity and safety of the entire shutdown cooling process.

[0086] This application also provides an electronic device for implementing various embodiments of this application, the electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0087] Those skilled in the art will understand that the electronic device structure involved in the embodiments of this application does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0088] In embodiments of this application, electronic devices include, but are not limited to, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices may also represent various forms of mobile devices and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of this application described and / or claimed herein.

[0089] In this application embodiment, the processor can be implemented using at least one of an Application-Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a processor, a controller, a microcontroller, a microprocessor, or an electronic unit designed to perform the functions described herein. In some cases, such implementations can be implemented within a controller. For software implementations, implementations such as processes or functions can be implemented with separate software modules that allow the performance of at least one function or operation. The software code can be implemented by a software application (or program) written in any suitable programming language, and the software code can be stored in memory and executed by the controller.

[0090] In addition, the electronic device includes some functional modules not shown, which will not be described in detail here.

[0091] Those skilled in the art will understand that the various aspects of the electronic device provided in this application can be implemented as a system, method, or program product. Therefore, the various aspects of this application can be specifically implemented in the following forms: a completely hardware implementation, a completely software implementation (including firmware, microcode, etc.), or a combination of hardware and software aspects, collectively referred to herein as a "circuit," "module," or "system."

[0092] This application also provides a storage medium storing a program product capable of implementing a counter-current rapid cooling method for a steam turbine. In some possible embodiments, various aspects of this application can also be implemented as a program product comprising program code that, when run on a terminal device, causes the terminal device to perform the steps described in the foregoing "Exemplary Methods" section of this specification according to various exemplary embodiments of this application.

[0093] The storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A counter-current rapid cooling system for a steam turbine, characterized in that, Including the turbine body and the rapid cooling device; The turbine body includes a high-pressure cylinder (1), an intermediate-pressure cylinder (2) and two low-pressure cylinders (3). The exhaust side of the high-pressure cylinder (1) is connected to the inlet side of the intermediate-pressure cylinder (2) through a high-pressure exhaust pipe. The exhaust side of the intermediate-pressure cylinder (2) is connected to the inlet side of the two low-pressure cylinders (3) through two intermediate-pressure exhaust pipes respectively. The rapid cooling device includes a pressurizing fan (4), an electric heater (5), a temperature chamber heater (6), a first heat exchanger (7), a second heat exchanger (8), and a third electric temperature chamber heater (9). The outlet of the pressurizing fan (4) is connected to the inlet of the electric heater (5) through the fan outlet pipe. The outlet of the electric heater (5) is connected to the inlet of the temperature chamber heater (6) through the heater outlet pipe. The outlet of the temperature chamber heater (6) is connected to the inlet of the first heat exchanger (7) through the first air supply pipe. The outlet of the temperature chamber heater (6) is connected to the inlet of the second heat exchanger (8) through the second air supply pipe. The outlet of the first heat exchanger (7) is connected to the exhaust side of the high-pressure cylinder (1) through the fast cooling inlet pipe on the high-pressure cylinder side, and the outlet of the second heat exchanger (8) is connected to the exhaust side of the medium-pressure cylinder (2) through the fast cooling inlet pipe on the medium-pressure cylinder side. The outlet of the pressurizing blower (4) is connected to the inlet of the third electric temperature box heater (9) through the third air supply pipe. The outlet of the third electric temperature box heater (9) is connected to the exhaust side of the two low-pressure cylinders (3) through the low-pressure cylinder side fast cooling air inlet pipe respectively. The steam inlet side of the high-pressure cylinder (1) is connected to the return gas end of the temperature box heater (6) through the high-pressure cylinder side fast cooling return gas pipe. The steam inlet side of the medium-pressure cylinder (2) is connected to the return gas end of the temperature box heater (6) through the medium-pressure cylinder side fast cooling return gas pipe. The steam inlet sides of the two low-pressure cylinders (3) are connected to the return gas end of the temperature box heater (6) through two low-pressure cylinder side fast cooling return gas pipes respectively.

2. The turbine counter-current rapid cooling system as described in claim 1, characterized in that, A high-pressure cylinder side rapid cooling intake pipe is provided with a high-pressure cylinder side rapid cooling intake valve, a medium-pressure cylinder side rapid cooling intake pipe is provided with a medium-pressure cylinder side rapid cooling intake valve, a low-pressure cylinder side rapid cooling intake pipe is provided with a low-pressure cylinder side rapid cooling intake valve corresponding to the low-pressure cylinder (3), a high-pressure cylinder side rapid cooling return pipe is provided with two parallel high-pressure cylinder side rapid cooling return valves, a medium-pressure cylinder side rapid cooling return pipe is provided with two parallel medium-pressure cylinder side rapid cooling return valves, and two low-pressure cylinder side rapid cooling return pipes are respectively provided with corresponding low-pressure cylinder side rapid cooling return valves. A high-pressure cylinder-side rapid cooling intake pipe is equipped with a high-pressure cylinder-side rapid cooling intake temperature sensor, a high-pressure cylinder-side rapid cooling return pipe is equipped with a high-pressure cylinder-side rapid cooling return pressure sensor, an intermediate-pressure cylinder-side rapid cooling intake pipe is equipped with an intermediate-pressure cylinder-side rapid cooling intake temperature sensor, an intermediate-pressure cylinder-side rapid cooling return pipe is equipped with an intermediate-pressure cylinder-side rapid cooling return pressure sensor, a low-pressure cylinder-side rapid cooling intake pipe is equipped with a low-pressure cylinder-side rapid cooling intake temperature sensor, and two low-pressure cylinder-side rapid cooling return pipes are each equipped with a corresponding low-pressure cylinder-side rapid cooling return pressure sensor.

3. The turbine counter-current rapid cooling system as described in claim 2, characterized in that, The outlet of the pressurizing blower (4) is connected to the rapid cooling inlet pipe on the high-pressure cylinder side and the rapid cooling inlet pipe on the medium-pressure cylinder side through the mixing pipe respectively; The section where the mixing pipe connects to the high-pressure cylinder side rapid cooling intake pipe is equipped with a high-pressure cylinder side rapid cooling mixing regulating valve, and the section where the mixing pipe connects to the medium-pressure cylinder side high-pressure cylinder side rapid cooling intake pipe is equipped with a medium-pressure cylinder side rapid cooling mixing regulating valve.

4. The turbine counter-current rapid cooling system as described in claim 2, characterized in that, The turbine counter-current rapid cooling system also includes a preheating circulation pipe and a pressure balance pipe. The preheating circulation pipe is connected to the rapid cooling inlet pipe on the high-pressure cylinder side and the rapid cooling inlet pipe on the intermediate-pressure cylinder side. The pressure balance pipe is connected to the rapid cooling return pipe on the intermediate-pressure cylinder side and the two rapid cooling return pipes on the low-pressure cylinder side. A preheating circulation valve is installed on the preheating circulation pipe, and a pressure balance valve is installed on the pressure balance pipe. The high-pressure cylinder side rapid cooling return pipe is also equipped with a high-pressure cylinder side rapid cooling return gas flow sensor and a high-pressure cylinder side rapid cooling return gas pressure sensor. The intermediate-pressure cylinder side rapid cooling return pipe is also equipped with an intermediate-pressure cylinder side rapid cooling return gas flow sensor and an intermediate-pressure cylinder side rapid cooling return gas pressure sensor. The two low-pressure cylinder side rapid cooling return pipes are respectively equipped with corresponding low-pressure cylinder side rapid cooling return gas temperature sensors.

5. The turbine counter-current rapid cooling system as described in claim 4, characterized in that, An air inlet valve is provided on the air outlet pipe of the blower, a blower exhaust valve is provided at the outlet of the pressurized blower (4), a heater exhaust valve is provided on the air outlet pipe of the heater, a first isolation valve is provided on the first air supply pipe, a second isolation valve is provided on the second air supply pipe, and a third isolation valve is provided on the third air supply pipe. The medium-pressure cylinder side rapid cooling return pipe is connected to the air inlet of the pressurizing blower through a circulation pipe, and the circulation pipe is equipped with a blower recirculation valve.

6. A method for rapid counter-current cooling of a steam turbine, characterized in that, Using the turbine counter-current rapid cooling system as described in any one of claims 1-5 includes the following steps: S1. After the turbine body is shut down and put into turning gear, the exhaust side metal wall temperature of each cylinder and the highest and lowest temperature points of each cylinder are collected. The exhaust side metal wall temperature of each cylinder is taken as the initial intake temperature for the cylinder's rapid cooling device to be put into operation, and the difference between the highest and lowest temperature points is taken as the initial temperature gradient when the cylinder is naturally cooled. The cylinder body includes a high-pressure cylinder (1), a medium-pressure cylinder (2), and two low-pressure cylinders (3); S2. Start the rapid cooling device. The cooling medium is drawn in by the pressurized fan (4) and then sequentially delivered to the fan outlet pipe, electric heater (5), heater outlet pipe, and temperature box heater (6) to heat the cooling medium. The temperature of the high-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the high-pressure cylinder (1) using the heated cooling medium, and the temperature of the medium-pressure cylinder side rapid cooling intake pipe is preheated to the initial intake temperature of the medium-pressure cylinder (2). S3. The cooling medium in the heat chamber heater (6) is sent to the first heat exchanger (7) through the first air supply pipe and to the second heat exchanger (8) through the second air supply pipe. At the same time, the cooling medium is sent to the third electric heat chamber heater (9) through the third air supply pipe by the pressurized fan (4) to circulate the cooling medium. Among them, the cooling medium sent into the first heat exchanger (7) enters the exhaust side of the high pressure cylinder (1) through the high pressure cylinder side fast cooling inlet pipe, flows out from the high pressure cylinder (1) inlet side, and returns to the return end of the temperature box heater (6) through the high pressure cylinder side fast cooling return pipe. The cooling medium fed into the second heat exchanger (8) is sent into the exhaust side of the intermediate pressure cylinder (2) through the rapid cooling inlet pipe on the intermediate pressure cylinder side, flows out from the inlet side of the intermediate pressure cylinder (2), and returns to the return end of the temperature box heater (6) through the rapid cooling return pipe on the intermediate pressure cylinder side. The cooling medium fed into the third electric temperature box heater (9) is heated by the third electric temperature box heater (9) and then sent to the exhaust side of the two low-pressure cylinders (3) through the two low-pressure cylinder side fast cooling inlet pipes respectively. It flows out from the inlet side of the low-pressure cylinder (3) and then returns to the return end of the temperature box heater (6) through the two low-pressure cylinder side fast cooling return pipes respectively. The heating power of the third electric temperature box heater (9) is set to make the temperature of the cooling medium after passing through the third electric temperature box heater (9) equal to the lower value of the initial inlet temperature of the two low-pressure cylinders. The flow direction of the cooling medium inside the turbine body is opposite to the flow direction of the normal operating medium in the turbine. During the cooling medium circulation process, the highest and lowest temperature points of each cylinder are obtained respectively. The difference between the highest and lowest temperature points of each cylinder is used as the real-time temperature gradient of that cylinder. The intake temperature of the cooling medium of each cylinder is adjusted according to the relationship between the real-time temperature gradient of each cylinder and the corresponding initial temperature gradient. S4. Stop rapid cooling when the maximum temperature inside all cylinders drops to the preset turning temperature threshold.

7. The counter-current rapid cooling method for a steam turbine as described in claim 6, characterized in that, Step S2 specifically includes: Open the first isolation valve, the second isolation valve, the preheating circulation valve, and the fan recirculation valve; close the high-pressure cylinder side rapid cooling intake valve and the medium-pressure cylinder side rapid cooling intake valve. Start the pressurizing fan (4) to draw in the cooling medium. The cooling medium enters the temperature box heater (6) in sequence through the fan outlet pipe, electric heater (5), and heater outlet pipe. During the process, the cooling medium is heated. After the heated cooling medium flows out from the heater (6) of the temperature box, part of it is sent to the fast cooling intake pipe on the high pressure cylinder side through the first air supply pipe and the first heat exchanger (7), and the other part is sent to the fast cooling intake pipe on the medium pressure cylinder side through the second air supply pipe and the second heat exchanger (8). The cooling medium sent into the high-pressure cylinder side rapid cooling intake pipe enters the medium-pressure cylinder side rapid cooling intake pipe through the preheating circulation pipe. After merging with the cooling medium in the medium-pressure cylinder side rapid cooling intake pipe, it returns to the intake end of the pressurizing blower (4) through the medium-pressure cylinder side rapid cooling return pipe and the blower recirculation valve, forming a circulating heating circuit. The preheating circulation valve is closed after the temperature of the high-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the high-pressure cylinder (1) and the temperature of the medium-pressure cylinder side rapid cooling intake pipe reaches the initial intake temperature of the medium-pressure cylinder (2), thus ending the preheating.

8. The counter-current rapid cooling method for a steam turbine as described in claim 6, characterized in that, In step S3, the specific steps for cooling medium circulation are as follows: Open the intake valve, the first isolation valve, the second isolation valve, the third isolation valve, the high-pressure cylinder side rapid cooling intake valve, the medium-pressure cylinder side rapid cooling intake valve, the two low-pressure cylinder side rapid cooling intake valves, the two high-pressure cylinder side rapid cooling return valves, the two medium-pressure cylinder side rapid cooling return valves, and the two low-pressure cylinder side rapid cooling return valves; The pressurized blower (4) is started to draw in and output the cooling medium. The first part of the cooling medium output by the pressurized blower (4) enters the temperature box heater (6) through the blower outlet pipe, electric heater (5), and heater outlet pipe in sequence. During the process, the cooling medium is heated. After the heated cooling medium flows out of the temperature box heater (6), part of it enters the exhaust side of the high-pressure cylinder (1) through the first air supply pipe and the first heat exchanger (7) and then through the high-pressure cylinder side fast cooling inlet pipe. It flows out from the high-pressure cylinder (1) steam inlet side and returns to the return end of the temperature box heater (6) through the high-pressure cylinder side fast cooling return pipe and the two high-pressure cylinder side fast cooling return valves. The other part of the heated cooling medium enters the exhaust side of the medium-pressure cylinder (2) through the medium-pressure cylinder side fast cooling inlet pipe after passing through the second air supply pipe and the second heat exchanger (8). It flows out from the medium-pressure cylinder (2) steam inlet side and returns to the return end of the temperature box heater (6) through the medium-pressure cylinder side fast cooling return pipe and the two medium-pressure cylinder side fast cooling return valves. The second part of the cooling medium output by the pressurizing fan (4) enters the third electric temperature box heater (9) for heating through the third air supply pipe, and then enters the exhaust side of the two low-pressure cylinders (3) through the two low-pressure cylinder side fast cooling air inlet pipes and the two low-pressure cylinder side fast cooling air inlet valves respectively. It flows out from the air inlet side of the low-pressure cylinder (3) and returns to the return end of the temperature box heater (6) through the two low-pressure cylinder side fast cooling return air pipes and the two low-pressure cylinder side fast cooling return air valves.

9. The counter-current rapid cooling method for a steam turbine as described in claim 6, characterized in that, In step S3, the specific operation of adjusting the intake temperature of the cooling medium for each cylinder based on the relationship between the real-time temperature gradient and the corresponding initial temperature gradient is as follows: When the real-time temperature gradient of the high-pressure cylinder (1) is greater than or equal to the initial temperature gradient of the high-pressure cylinder (1) minus the preset temperature difference, the temperature of the cooling medium entering the high-pressure cylinder (1) is maintained; when the real-time temperature gradient of the high-pressure cylinder (1) is less than the initial temperature gradient of the high-pressure cylinder (1) minus the preset temperature difference, the opening of the high-pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurizing fan (4) directly entering the fast cooling intake pipe on the high-pressure cylinder side, thereby reducing the temperature of the cooling medium entering the high-pressure cylinder (1); When the real-time temperature gradient of the intermediate pressure cylinder (2) is greater than or equal to the initial temperature gradient of the intermediate pressure cylinder (2) minus the preset temperature difference, the temperature of the cooling medium entering the intermediate pressure cylinder (2) is maintained; when the real-time temperature gradient of the intermediate pressure cylinder (2) is less than the initial temperature gradient of the intermediate pressure cylinder (2) minus the preset temperature difference, the opening of the intermediate pressure mixing regulating valve is adjusted to increase the proportion of the cooling medium in the pressurizing fan (4) directly entering the fast cooling intake pipe on the intermediate pressure cylinder side, thereby reducing the temperature of the cooling medium entering the intermediate pressure cylinder (2); When the real-time temperature gradient of both low-pressure cylinders (3) is greater than or equal to the initial temperature gradient of the low-pressure cylinder (3) minus the preset temperature difference, the temperature of the cooling medium entering the low-pressure cylinder is maintained; when the real-time temperature gradient of any low-pressure cylinder (3) is less than the initial temperature gradient of the low-pressure cylinder (3) minus the preset temperature difference, the heating power of the third electric temperature box heater (9) is reduced, and the temperature of the cooling medium entering the low-pressure cylinder (3) is reduced.

10. The counter-current rapid cooling method for a steam turbine as described in claim 6, characterized in that, Step S3 also includes: During the cooling medium circulation process, the opening of the fast cooling intake valve on the high-pressure cylinder side and the fast cooling intake valve on the intermediate-pressure cylinder side are adjusted to make the fast cooling return pressure on the high-pressure cylinder side greater than that on the intermediate-pressure cylinder side; and the pressure balance valve is opened to make the fast cooling return pressure on the intermediate-pressure cylinder side less than that on the low-pressure cylinder side.

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