Variable working condition self-balancing free type drainage system and drainage structure

Abstract

This application discloses a variable-condition self-balancing free-type condensate drainage system and a condensate drainage structure. The condensate drainage structure is used in a condenser steam jet vacuum system, including a condenser with a condensate outlet. The condensate outlet is connected to the condenser's hot well via a U-shaped condensate drainage pipe. The U-shaped condensate drainage pipe includes a left riser connected to the condenser, a bottom connecting pipe, and a right riser connected to the hot well. The pressure provided by the liquid column in the right riser is greater than the pressure difference between the condenser and the hot well. A water seal is always maintained in the U-shaped condensate drainage pipe to isolate the condenser and the hot well. This application eliminates a large number of redundant configurations such as level gauges, remote thermal control instruments, condensate control gates, equipment instruments and valve point positioning cards, control cables, and multi-stage water seals. It also solves the problems of low heat exchange surface utilization, large selection size, large footprint, and difficult system installation and site selection in traditional condenser operation with water level, saving a significant amount of system equipment and maintenance costs.

Description

Technical Field

[0001] This application discloses a variable-condition self-balancing free-type drainage system and drainage structure, which relates to the field of steam jet technology. Background Technology

[0002] In thermal power plants, the condenser steam jet vacuum system is used to extract non-condensable gases from the condenser. These non-condensable gases mix with the steam in the ejector to form a steam-gas mixture, which is then condensed and cooled in the condenser (also called a heat exchanger). The cooled condensate is discharged to the condenser's hot well through a drain pipe, while the non-condensable gases in the condenser are released to the atmosphere. Because the condenser's hot well needs to maintain a low-pressure vacuum (approximately 4-10 kPa), the pressure in each stage of the condenser, under the pressure of the motive steam, is typically between low-pressure vacuum and slightly above atmospheric pressure (taking standard atmospheric pressure of 101.3 kPa as an example).

[0003] There are two problems here. First, the condenser needs to discharge non-condensable gases to the atmosphere. Second, the pressure in the condenser is greater than the pressure in the hot well. When the condenser drains water into the hot well, effective measures need to be taken to isolate the condenser and the hot well in order to maintain the low-pressure vacuum of the condenser.

[0004] Regarding the first question, the current technical solution is to adopt a multi-stage condenser structure. Figure 1 The diagram shows a three-stage condenser steam jet vacuum system, including a first-stage condenser 1, a second-stage condenser 2, and a third-stage condenser 3. The cooling water for the condensers comes from the cooling water inlet pipe 4. Non-condensable gases in the condenser originate from the high-pressure side vacuum header 5 and the low-pressure side vacuum header 6, respectively. Two first-stage ejectors 7 extract the non-condensable gases from the high-pressure side vacuum header 5 and the low-pressure side vacuum header 6, respectively. The nozzles of both first-stage ejectors 7 are connected to the shell-side inlet of the first-stage condenser 1. A second-stage ejector 8 extracts the non-condensable gases from the first-stage condenser 1. The non-condensable gas in the first stage ejector 7, the second stage ejector 8 is connected to the shell-side inlet of the second stage condenser 2, and the third stage ejector 9 extracts the non-condensable gas in the second stage condenser 2. The injection port of the third stage ejector 9 is connected to the shell-side inlet of the third stage condenser 3. The power source of the first stage ejector 7, the second stage ejector 8 and the third stage ejector 9 all come from the power steam in the power steam pipeline 10. Under the stepwise pressurization of the power steam, the shell-side pressure in the third stage condenser 3 is slightly higher than the atmospheric pressure. Therefore, the non-condensable gas in the third stage condenser 3 can be directly discharged to the atmosphere.

[0005] Regarding the second question, the current technical solution is: Figure 1The drainage structure within the square frame includes a multi-stage water seal structure 11 and a drain valve 12 installed on the drain pipes of the drain outlets of each stage of the condenser. A level gauge 13 is installed inside the condenser. The multi-stage water seal structure 11 maintains the isolation between the condenser and the hot well. At the same time, the level gauge 13 is used to observe the liquid level inside the condenser, thereby monitoring the status of the water seal and preventing water seal failure. When the liquid level inside the condenser is higher than the target value, the water seal is normal. When the liquid level inside the condenser drops significantly below the target value, the drain valve 12 can be closed to ensure the isolation between the condenser and the hot well, thus maintaining the low-pressure vacuum of the condenser.

[0006] The problems arising from using the above structure to isolate the condenser and the hot well include:

[0007] First, excessive auxiliary structures, such as level gauges, steam traps, and multi-stage water seals, result in numerous components. In actual use, this can easily lead to issues such as jamming, leakage, demagnetization, electromagnetic interference, instrument malfunctions, cable faults, blind spots in the measuring range, and exceeding the measuring range limit. Even with multi-stage water seals, it's still impossible to prevent malfunctions in steam trap control parameters, leading to malfunctions or failures to operate the steam trap control valve, resulting in uncontrolled condenser levels, damaged condenser vacuum, and compromised unit operational safety. Furthermore, erroneous level gauge readings severely impact system fault handling and troubleshooting efficiency, resulting in significant waste of human resources.

[0008] Second, the water seal in the condenser needs to maintain a certain liquid level at all times. Only the part of the heat exchange surface of the condenser that is above the liquid level can perform the heat exchange function. This leads to a decrease in the condensation heat exchange efficiency of the condenser. In order to achieve the preset condensation heat exchange efficiency, a larger condenser must be used, which leads to an increase in the overall structural volume and weight.

[0009] Third, the excessive auxiliary structures and larger-sized condensers result in a large overall size of the steam jet vacuum system. As a higher installation platform, the existing steam jet vacuum system cannot be installed on the central level of the turbine hall due to the need for compactness. This results in insufficient vertical height for water sealing, so multi-stage water sealing is necessary. This, in turn, leads to an increase in auxiliary structures and a larger overall size of the steam jet vacuum system, thus creating a vicious cycle. Summary of the Invention

[0010] The purpose of this application is to address the problems identified in the background section.

[0011] To achieve the above objectives, on the one hand, the technical solution of this application provides a variable operating condition self-balancing free-type condensate drainage structure for a condenser steam jet vacuum system. The condenser steam jet vacuum system is equipped with a condenser, and the condenser is equipped with a condensate drain. The condensate drain is connected to the condenser's hot well via a U-shaped condensate drain pipe. The U-shaped condensate drain pipe includes a left riser, a bottom connecting pipe, and a right riser. The top of the left riser is connected to the condenser, and the top of the right riser is connected to the hot well. The pressure provided by the liquid column in the right riser is greater than the pressure difference between the condenser and the hot well, so that all condensers can operate without water level control, achieving the purpose of variable operating condition self-balancing free-type condensate drainage.

[0012] Furthermore, the bottom of the U-shaped drainage pipe is provided with a sewage sampling port.

[0013] On the other hand, this application also provides a variable operating condition self-balancing free-type condensate drain system, including a condenser steam injection vacuum system and a condensate drainage structure, wherein the condenser steam injection vacuum system includes...

[0014] Condenser, wherein the condenser is equipped with a vacuum header;

[0015] Power steam pipeline;

[0016] Multistage injectors;

[0017] Multistage condenser;

[0018] In a multi-stage ejector, the suction port of the first-stage ejector is connected to the vacuum main pipe, the power steam port is connected to the power steam pipeline, and the ejector port is connected to the shell-side inlet of the same-stage condenser.

[0019] In a multi-stage ejector, the suction port of the intermediate stage ejector is connected to the shell-side outlet of the previous stage condenser, the power steam port is connected to the power steam pipeline, and the injection port is connected to the shell-side inlet of the same stage condenser.

[0020] The suction port of the last stage ejector in the multi-stage ejector is connected to the shell-side outlet of the previous stage condenser, the power steam port is connected to the power steam pipeline, and the injection port is connected to the shell-side inlet of the last stage condenser.

[0021] The shell-side outlet of the last stage condenser is discharged to the atmosphere;

[0022] The condensers are all equipped with drain outlets, and the drain structure includes a U-shaped drain pipe. The drain outlets are all connected to the hot well of the condenser via the U-shaped drain pipe. The U-shaped drain pipe includes a left riser, a bottom connecting pipe, and a right riser. The top of the left riser is connected to the condenser, and the top of the right riser is connected to the hot well. The pressure provided by the liquid column in the right riser is greater than the pressure difference between the condenser and the hot well.

[0023] Preferably, the condenser is provided with a condensate pipe, the condensate pipe is provided with a branch pipe, and the branch pipe is provided as a cooling water inlet pipe connected to the condenser.

[0024] Preferably, the vacuum main pipe includes a high-pressure side vacuum main pipe and a low-pressure side vacuum main pipe, and two first-stage ejectors are provided, with the suction ports of the two first-stage ejectors respectively connected to the high-pressure side vacuum main pipe and the low-pressure side vacuum main pipe.

[0025] Preferably, the height of the left riser is set as h1 and the height of the right riser is set as h2, then:

[0026] ρgh2>k1(p3-p0) (1)

[0027] Where ρ is the hydrophobic density, g is the gravitational acceleration, p3 is the pressure inside the last stage condenser, p0 is the pressure inside the hot well, and k1 is the first safety factor.

[0028] Before the left riser is filled with liquid, the liquid in the U-shaped drain pipe is discharged to the hot well. That is, the pressure of the condenser plus the liquid column pressure of the left riser when it is full is greater than the pressure of the hot well plus the liquid column pressure of the right riser when it is full.

[0029] p1+ρgh1>k2(ρgh2+p0) (2)

[0030] Where p1 is the pressure inside the first-stage condenser and k2 is the second safety factor.

[0031] Let the diameter of the U-shaped drainage pipe be D, the total length be l, and the flow velocity of the drainage pipe be v. Then:

[0032]

[0033]

[0034] In the formula, ω is the known drainage flow rate, the drainage velocity v ranges from 0.2 to 0.5 m / s, h is the liquid level height of the left riser, with a maximum of h1, and λ is the friction coefficient of the drain pipe.

[0035] The condensate drainage structure provided in this application enables a condenser steam jet vacuum system with variable operating conditions and self-balancing free-flow condensate drainage. This completely replaces the traditional condenser steam jet vacuum system's water-level operation mode, which uses a level gauge as the control parameter for the condenser, eliminating the need to open and close the condensate control valve to adjust the liquid level and maintain the unit's vacuum. Its waterless operation mode not only eliminates a large number of redundant components such as level gauges, remote thermal control instruments, condensate control valves, equipment instruments and valve positioning devices, control cables, and multi-stage water seals, but also solves the problems of low condenser heat exchange surface utilization, large component size, large footprint, and difficult system installation and site selection associated with water-level operation modes, thus saving significant system equipment and maintenance costs.

[0036] It has the following advantages:

[0037] (1) The condenser steam jet vacuum system with variable operating conditions and self-balancing free-type condenser condenser is installed in a more advantageous location (the central layer of the compact turbine hall). After the equipment is installed, the condenser condenser flow rate, condenser resistance, pipe resistance, water seal height and condenser flow velocity are calculated in a targeted manner. During operation, the water level line fluctuates only in the condenser ...

[0038] (2) The steam jet vacuum system of the condenser with variable operating conditions and self-balancing free-type condenser is selected with the optimal condenser pipe diameter and the optimal water seal height. This not only ensures that the condenser flow rate is completely discharged to the unit condenser, but also ensures that the atmosphere does not leak into the condenser during system operation and standby.

[0039] (3) Variable operating condition self-balancing free-type condenser steam jet vacuum system. This method does not require the installation of condenser level gauge, remote instrument, condensate control door and supporting control cables and cards. It has made great optimizations to the traditional condenser steam jet vacuum system with redundant configuration, improving system safety and stability while reducing leakage risk and maintenance.

[0040] (4) The condenser steam jet vacuum system with variable operating conditions and self-balancing free-flowing condensate can realize online leak detection of the condenser without the need for multi-stage water seals. When the condensate water quality of the unit exceeds the standard and it is necessary to determine whether there is a leak in the condenser of the system, it can meet the needs of water quality sampling and leak detection through the bottom drain sampling port of the water seal in both system operation and standby states. It can also meet the needs of periodic leak detection of the condenser through periodic sampling and testing. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a condenser steam jet vacuum system in the prior art;

[0042] Figure 2 This is a schematic diagram of a variable-condition self-balancing free-type hydrophobic system provided in the embodiment.

[0043] Figure 3 This is a schematic diagram of the hydrophobic drainage structure provided in the embodiment. Detailed Implementation

[0044] To make this application more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0045] Example

[0046] This embodiment provides a variable-condition self-balancing free-type condensate drainage system and condensate drainage structure. Based on existing technology, this embodiment improves the condensate drainage structure used in multi-stage condenser steam jet vacuum systems. Taking a three-stage condenser steam jet vacuum system as an example, see details below. Figure 2 and Figure 3 The steam jet vacuum system for multi-stage condensers can be similarly deduced.

[0047] The three-stage condenser steam jet vacuum system includes

[0048] First-stage condenser 1, second-stage condenser 2, and third-stage condenser 3;

[0049] First-stage injector 7, second-stage injector 8, and third-stage injector 9;

[0050] Condenser, which is generally equipped with condensate pipe 14, high-pressure side vacuum header 5 and low-pressure side vacuum header 6, and vacuum pump set 15 connected to the ends of high-pressure side vacuum header 5 and low-pressure side vacuum header 6.

[0051] 10 steam pipelines for power generation;

[0052] Two first-stage ejectors 7 are provided. The suction ports of the two first-stage ejectors 7 are connected to the high-pressure side vacuum header 5 and the low-pressure side vacuum header 6, respectively. The power steam ports of the two first-stage ejectors 7 are both connected to the power steam pipeline 10. The ejection ports of the two first-stage ejectors 7 are both connected to the shell-side inlet of the first-stage condenser 1. The first-stage ejectors 7 use power steam to extract uncondensed gas from the high-pressure side vacuum header 5 and the low-pressure side vacuum header 6, and pressurize the gas-water mixture to bring it into the first-stage condenser 1, where it undergoes heat exchange and condensation. The suction port of the second-stage ejector 8 is connected to the shell-side outlet of the first-stage condenser 1, and the power steam port of the second-stage ejector 8 is connected to the power steam pipeline 10. The nozzle of the second-stage ejector 8 is connected to the shell-side inlet of the second-stage condenser 2. The second-stage ejector 8 draws uncondensed gas from the first-stage condenser 1, pressurizes it, and sends it into the second-stage condenser 2, where it continues to exchange heat and condense. The suction port of the third-stage ejector 9 is connected to the shell-side outlet of the second-stage condenser 2, and the power steam port of the third-stage ejector 9 is connected to the power steam pipe 10. The nozzle of the third-stage ejector 9 is connected to the shell-side inlet of the third-stage condenser 3. The third-stage ejector 9 draws uncondensed gas from the second-stage condenser 2, pressurizes it, and sends it into the third-stage condenser 3, where it continues to exchange heat and condense. The uncondensed gas in the third-stage condenser 3 is directly discharged into the atmosphere.

[0053] A branch pipe is led out from the condensate pipe 14 as a cooling water inlet pipe 4, which is connected to the water-side inlet of the first-stage condenser 1, the second-stage condenser 2 and the third-stage condenser 3 to provide cooling water for each stage of condenser. The water-side outlets of each stage of condenser converge and are then connected back to the condensate pipe 14.

[0054] The drainage structures used in the first-stage condenser 1, the second-stage condenser 2, and the third-stage condenser 3 are as follows: Figure 2 Inside the box and Figure 3 As shown, the first-stage condenser 1, the second-stage condenser 2, and the third-stage condenser 3 are equipped with drain ports, all of which are connected to the hot well (low-pressure vacuum, generally 4 kPa) via U-shaped drain pipes 16. Since the internal pressure of the first-stage condenser 1, the second-stage condenser 2, and the third-stage condenser 3 gradually increases, with the internal pressure of the third-stage condenser 3 generally exceeding 101.3 kPa, the pressure difference between the third-stage condenser 3 and the hot well is the largest. When draining water, as long as the height of the U-shaped drain pipe 16 connected to the third-stage condenser 3 meets the water seal requirements, the U-shaped drain pipes 16 connected to the first-stage condenser 1 and the second-stage condenser 2 will also naturally meet the water seal requirements. Specifically, the U-shaped drain pipe 16 includes a left riser, a bottom connecting pipe, and a right riser. The top of the left riser connects to the condenser, and the top of the right riser connects to the hot well. The height of the left riser is set as h1, and the height of the right riser is set as h2. Therefore, the following conditions must be met:

[0055] The pressure provided by the liquid column filling the right riser is greater than the pressure difference between the third-stage condenser 3 and the hot well:

[0056] ρgh2>k1(p3-p0) (1)

[0057] Where ρ is the hydrophobic density, g is the gravitational acceleration, p3 is the pressure inside the third-stage condenser 3, p0 is the pressure inside the hot well, and k1 is the first safety factor.

[0058] When the above conditions are met, the right riser of the U-shaped drain pipe 16, after being filled with liquid, can resist the pressure difference between the third-stage condenser 3 and the hot well, and always maintain a water seal in the U-shaped drain pipe 16. Therefore, the U-shaped drain pipe 16 can achieve the isolation between the third-stage condenser 3 and the hot well. The pressure difference between the first-stage condenser 1, the second-stage condenser 2 and the hot well is even lower, which can also achieve the purpose of isolation.

[0059] In one possible implementation, the bottom of the U-shaped drainage pipe 16 is provided with a sewage sampling port, which can be opened to drain sewage or take samples for testing when blockage occurs.

[0060] Furthermore, the left riser should be able to drain the liquid from the U-shaped drain pipe 16 to the hot well before it becomes full. That is, the condenser pressure plus the liquid column pressure of the left riser when it is full should be greater than the hot well pressure plus the liquid column pressure of the right riser when it is full. Since the pressure is lowest in the first-stage condenser 1, this requirement must be met.

[0061] p1+ρgh1>k2(ρgh2+p0) (2)

[0062] Where p1 is the internal pressure of the first-stage condenser 1, and k2 is the second safety factor. The U-shaped drain pipe 16 acts as a water seal, which is actually a balancing connector. Water will only flow when the static pressure on the left is greater than the static pressure on the right, discharging condensate from the left to the right. In a multi-stage condenser, the first-stage condenser has the lowest pressure. When the above formula is satisfied, the first-stage condenser can discharge condensate to the hot well. The second and third-stage condensers have higher pressures and can also discharge condensate to the hot well.

[0063] Furthermore, for a specific condenser model, the condensate flow rate ω (t / h) can be determined based on its operating conditions. The selection of the drain pipe diameter needs to be compatible with the condensate flow rate to ensure that the condensate velocity v is within a suitable range of 0.2–0.5 m / s. Typically, there are multiple available drain pipe diameters D. Substituting the available drain pipe diameters D into the following formula, the condensate velocity v can be calculated.

[0064]

[0065] The pipe diameters that meet the requirement of a drainage velocity v between 0.2 and 0.5 m / s are considered as candidate pipe diameters, and the set of candidate pipe diameters is denoted as S. D ={d1...di...dn}, and the drainage velocity corresponding to the selected pipe diameter di is denoted as vi;

[0066] Substitute di and vi into the following formula in sequence to verify.

[0067]

[0068] In the formula, h is the liquid level height of the left riser, which can be up to h1, λ is the friction coefficient of the drain pipe, which represents the resistance of the liquid flow in the drain pipe, and l is the total length of the drain pipe. The above formula expresses that the power of the drainage flow must be greater than the resistance of the pipe to ensure smooth flow. Otherwise, the drainage will be obstructed, causing the condenser to fill with water and causing an accident. The pipe diameter that satisfies formula (3) and formula (4) is the actual usable pipe diameter.

[0069] The above formula describes the standard conditions that the U-shaped drainage pipe 16 should meet. In actual manufacturing and use, the following empirical formulas can be referenced.

[0070] When the pressure inside the condenser is in equilibrium with the pressure in the hot well, the system flow resistance is stable. It is required that h1 is 20% or more greater than h2, so h1≥1.2·h2;

[0071] When the pressure inside the condenser is greater than the pressure in the hot well, the system flow resistance changes slightly, requiring h1 to be 50% or more greater than h2, so h1≥1.5·h2;

[0072] Because the available installation locations for the system within the turbine room are extremely limited, the installation height of the condenser is relatively fixed. Generally, h1 is required to be 20% to 50% larger than h2. Therefore, the proportional coefficients k1 and k2 are taken as 1.2 to 1.5.

[0073] In summary, this embodiment provides a variable-condition self-balancing free-type condensate drain system and condensate drainage structure. Through targeted calculations of condensate flow rate, condensate resistance, pipe resistance, water seal height, and condensate flow velocity, the optimal condensate pipe diameter and optimal water seal height are designed to ensure complete drainage of the condenser condensate from the condenser steam jet vacuum system under various unit loads and operating conditions, while simultaneously preventing atmospheric leakage into the condenser through the air exhaust pipe. The designed water seal enables online sampling to monitor for leaks in the condenser tube sheet. Therefore, this application has the following advantages:

[0074] 1. The system footprint has been reduced, and the equipment can be installed in a more advantageous location (the central floor of the compact turbine room), enabling the condenser to operate without water level (water-free operation mode) during operation.

[0075] 2. Improved the utilization rate of the condenser heat exchange area (no water level is required inside the condenser during operation);

[0076] 3. The traditional condenser level gauge has been eliminated;

[0077] 4. The instrumentation equipment required for remote transmission of traditional condenser level gauges has been eliminated;

[0078] 5. The condensate control gate required for traditional condenser level control has been eliminated;

[0079] 6. The cables and clips required for the traditional condenser level gauge remote transmission and condensate control gate have been eliminated.

Claims

1. A variable-condition self-balancing free-type condensate drainage structure for use in a condenser steam jet vacuum system, wherein the condenser steam jet vacuum system is equipped with a condenser, characterized in that, The condenser is equipped with a drain outlet, which is connected to the condenser's hot well via a U-shaped drain pipe. The U-shaped drain pipe includes a left riser, a bottom connecting pipe, and a right riser. The top of the left riser is connected to the condenser, and the top of the right riser is connected to the hot well. The pressure provided by the liquid column in the right riser is greater than the pressure difference between the condenser and the hot well, so that all condensers can operate without water level control, achieving the purpose of variable operating condition self-balancing free draining.

2. The variable-condition self-balancing free-type drainage structure according to claim 1, characterized in that, The bottom of the U-shaped drainage pipe is equipped with a sewage sampling port.

3. A variable-condition self-balancing free-type condensate drain system, comprising a condenser steam injection vacuum system and a condensate drainage structure, wherein the condenser steam injection vacuum system includes... Condenser, wherein the condenser is equipped with a vacuum header; Power steam pipeline; Multistage injectors; Multistage condenser; In a multi-stage ejector, the suction port of the first-stage ejector is connected to the vacuum main pipe, the power steam port is connected to the power steam pipeline, and the ejector port is connected to the shell-side inlet of the same-stage condenser. In a multi-stage ejector, the suction port of the intermediate stage ejector is connected to the shell-side outlet of the previous stage condenser, the power steam port is connected to the power steam pipeline, and the injection port is connected to the shell-side inlet of the same stage condenser. The suction port of the last stage ejector in the multi-stage ejector is connected to the shell-side outlet of the previous stage condenser, the power steam port is connected to the power steam pipeline, and the injection port is connected to the shell-side inlet of the last stage condenser. The shell-side outlet of the last stage condenser is discharged to the atmosphere; Its features are, The condensers are all equipped with drain outlets, and the drain structure includes a U-shaped drain pipe. The drain outlets are all connected to the hot well of the condenser via the U-shaped drain pipe. The U-shaped drain pipe includes a left riser, a bottom connecting pipe, and a right riser. The top of the left riser is connected to the condenser, and the top of the right riser is connected to the hot well. The pressure provided by the liquid column in the right riser is greater than the pressure difference between the condenser and the hot well.

4. A variable-condition self-balancing free-type drainage system according to claim 3, characterized in that, The condenser is provided with a condensate pipeline, and the condensate pipeline has a branch pipe, which is a cooling water inlet pipe connected to the condenser.

5. A variable-condition self-balancing free-type drainage system according to claim 3, characterized in that, The vacuum main pipe includes a high-pressure side vacuum main pipe and a low-pressure side vacuum main pipe. There are two first-stage ejectors, and the suction ports of the two first-stage ejectors are respectively connected to the high-pressure side vacuum main pipe and the low-pressure side vacuum main pipe.

6. A variable-condition self-balancing free-type drainage system according to claim 3, characterized in that, If the height of the left riser is set as h1 and the height of the right riser is set as h2, then: （1） in Hydrophobic density, p3 is the acceleration due to gravity, p0 is the pressure inside the last stage condenser, p0 is the pressure inside the hot well, and k1 is the first safety factor.

7. A variable-condition self-balancing free-type drainage system according to claim 6, characterized in that, The condenser pressure plus the liquid column pressure of the left riser filled with liquid is greater than the hot well pressure plus the liquid column pressure of the right riser filled with liquid: （2） in, The pressure inside the first-stage condenser. This is the second safety factor.

8. A variable-condition self-balancing free-type drainage system according to claim 7, characterized in that, The diameter of the U-shaped drainage pipe is denoted as D, and its total length is denoted as... l The flow velocity of the drainage pipe in the U-shaped drainage pipe is denoted as v ,but: （3） （4） In the formula, ω Given the hydrophobic flow rate and hydrophobic flow velocity... v The range is 0.2~0.5 m / s, where h is the liquid level height in the left riser, with a maximum value of h1. This is the friction coefficient of the drainage pipe.

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