A multi-back pressure condenser pressure isolation cold state simulation test system and method

Abstract

The application discloses a kind of multi-back pressure condenser pressure isolation sealing cold-state simulation test system and method, including test device ontology, gas supply system, feedwater system;It is mainly composed of water tank, centrifugal water pump, water mass flow meter, test device ontology, replaceable pressure isolation sealing test piece, air compressor, high-pressure gas tank, gas flow meter and the connecting pipeline and valve between;Cold-state simulation test can be carried out, to spray pure water instead of condensate, air instead of steam, study different condensate supply mode, different pressure isolation sealing form and the leakage gas volume and water volume of condensing pipe and pressure isolation plate narrow gap under various working pressure difference conditions, and observe the flow and distribution state of condensate at the import and export of narrow gap under different conditions, can be combined with test result analysis condensate flow, working parameter, pressure isolation sealing form and so on to the influence of leakage amount.The application can provide guidance for the design of multi-back pressure condenser.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of multi-back pressure condenser pressure isolation sealing test system, and particularly relates to a multi-back pressure condenser pressure isolation sealing cold state simulation test system and method. BACKGROUND

[0002] In recent years, "energy saving and emission reduction" has been paid more and more attention, especially in power plants, so the economy of the power plant unit should be improved as much as possible. The condenser is a key component in the power plant unit, and plays a crucial role in the economy of the power plant. The condenser is mainly used for condensing the exhaust steam discharged from the main steam turbine and part of the auxiliary steam turbine and receiving the drain, and establishing and maintaining a certain vacuum degree at the exhaust port of the steam turbine. The higher the vacuum degree in the condenser, i.e. the lower the back pressure, the lower the exhaust pressure of the steam turbine, and the higher the thermal efficiency and the better the economy of the power plant unit.

[0003] At present, most of the condensing steam turbines in power plants are designed to have a single back pressure value, i.e. the condenser matched therewith has a single design pressure value. Such a condenser is called a single pressure condenser. If the low pressure steam turbine has multiple exhaust cylinders, and the condenser is designed to have multiple independent steam chambers corresponding to the exhaust cylinders to receive the exhaust steam from the exhaust cylinders, such a condenser is called a multi-back pressure condenser, which can enable the steam turbine to operate at multiple different back pressure values. Previous studies have shown that the use of a multi-back pressure condenser can reduce the average back pressure of the exhaust steam of the steam turbine and improve the thermal efficiency of the unit.

[0004] The multi-back pressure condenser divides a shell into multiple cavities along the direction of the condensing pipe, and the cavities have different back pressures and exist pressure difference. The cavities are separated by partition plates, and the condensing pipe passes through the partition plates between different cavities. However, there are still some problems in the pressure isolation sealing between different cavities of the multi-back pressure condenser. Due to the limited process capacity and for the convenience of installation, an annular gap is generated between the partition plate separating the cavities with different back pressures and the condensing pipe. Under the action of the pressure difference between the cavities, the high pressure side will leak to the low pressure side, which will affect the establishment of the back pressure on both sides and further affect the condensing efficiency of the condenser. Some pressure isolation sealing measures have been used in the early stage, such as inserting a plastic sleeve between the hole of the pressure isolation plate and the cooling pipe. This structure can prevent steam leakage, but the work is large, and the cooling pipe is difficult to replace. A more ideal measure is the liquid self-sealing method: a layer of liquid film is naturally generated on the surface of the condensing pipe of the condenser during work. This layer of liquid film is continuously pushed by the pressure difference between the low pressure and high pressure chambers, and flows from the high pressure side to the low pressure side along the condensing pipe at a low speed. This layer of liquid film seals the annular gap between the tube plate and the heat exchange pipe to achieve the purpose of sealing the steam. However, there is no multi-back pressure condenser pressure isolation sealing test data in the currently published literature. SUMMARY

[0005] In view of the prior art, the present application aims to provide a multi-back pressure condenser pressure isolation sealing cold state simulation test system and method, which uses air to simulate steam and sprays pure water instead of condensate to test the effect of different multi-back pressure condenser pressure isolation sealing measures, obtains corresponding test data, and selects the optimal pressure isolation sealing measure, thereby laying a foundation for the design of multi-back pressure condenser.

[0006] To solve the above technical problems, the present application provides a multi-back pressure condenser pressure isolation sealing cold state simulation test system, which comprises a test device body, a gas supply system and a water supply system.

[0007] The test device body comprises a low pressure chamber and a high pressure chamber separated by a partition plate, the low pressure chamber is provided with an exhaust port communicated with the atmosphere through an exhaust valve and a drain port connected with a drain valve, and the high pressure chamber is provided with a water supply port, a drain port connected with the drain valve, an air inlet and an exhaust port communicated with the atmosphere through an exhaust valve; the partition plate between the two chambers is provided with replaceable pressure isolation sealing test pieces; the high pressure chamber is provided with a detachable end cover for replacing and installing the replaceable pressure isolation sealing test pieces and adjusting the water supply mode; the replaceable pressure isolation sealing test pieces comprise a metal pipe and an outer pipe sleeve, the metal pipe penetrates through the partition plate, and the outer pipe sleeve is fixedly installed on the partition plate; the metal pipe and the outer pipe sleeve are tightly fitted at one end close to the partition plate to form a narrow annular gap, and are tightly fitted at the other end away from the partition plate.

[0008] The water supply system comprises a water pump, a water tank providing a water source for the water pump and a mass flow meter measuring the water supply flow; the water tank is connected with the water pump through a pre-pump valve, the water pump is connected with the mass flow meter through a post-pump valve and a pre-flow meter valve in sequence, and the mass flow meter is connected with the water supply port of the test device body through a water supply adjusting valve; a bypass valve is arranged between the pre-flow meter valve and the post-pump valve to return the bypass adjusting flow to the water tank.

[0009] The gas supply system comprises an air compressor, a gas tank storing buffer gas and a gas flow meter measuring the gas flow; the air compressor pumps air into the gas tank through a valve, and the gas tank is connected with the air inlet of the high pressure chamber through a gas main switch, the gas flow meter and an air inlet valve.

[0010] Further, two grooves are arranged on the outer pipe sleeve.

[0011] Further, pressure measuring points are arranged on the low pressure chamber and the high pressure chamber to obtain pressure values.

[0012] Further, the water pump is a centrifugal water pump or a syringe pump.

[0013] Further, a nozzle is installed at the water supply port in the high pressure chamber, and the installation angle of the nozzle is adjusted to realize water supply or a syringe needle is connected with the water supply port to ensure that the needle tip extends into the annular gap to realize water injection.

[0014] The application also comprises a kind of pressure isolation sealing cold state simulation test method of multi-back pressure condenser, using any one of the above systems, comprising:

[0015] A, test preparation: open the end cover of high pressure chamber, install replaceable pressure isolation sealing test piece on the test body baffle, if the test contains water supply process, install water supply device according to the water supply mode, then install end cover, connect gas supply system pipeline, if the test contains water supply process, connect water supply pipeline;

[0016] B, test start stage: start air compressor, open each valve, then close each vent of two chambers of test bench, fill air into two chambers, close valve after establishing set pressure, maintain this state for 3-5min, if chamber can maintain constant pressure, consider that chamber sealing is perfect, can continue test;Open low pressure chamber drain and outlet, make low pressure chamber reduce to atmospheric pressure and maintain pressure to atmospheric pressure during test;If the test contains water supply process, check whether water supply pipeline is normal and open water pump, then adjust water supply flow to test requirement and maintain constant;

[0017] C, test stage: open high pressure chamber air charging valve, adjust air charging flow to make high and low pressure chamber differential pressure to test required data point, record gas flowmeter reading after flow stabilizes, if the test contains water supply process, measure narrow gap water flow at low pressure chamber drain by weighing method, calculate water flow of each given time, after measuring one differential pressure, change to next differential pressure for test, until all set differential pressures are measured completely.

[0018] The beneficial effects of the application are as follows:

[0019] 1, the test system can measure leakage gas and water flow of condenser tube and pressure isolation plate under different pressure isolation sealing forms and various working pressure differentials, and observe flow and distribution state of condensate at narrow gap inlet and outlet under different conditions.

[0020] 2, the test system can analyze influence of condensate flow, pressure isolation sealing form working parameter on leakage amount combined with test results, and guide multi-back pressure condenser design. DETAILED DESCRIPTION

[0021] Figure 1 is a pressure isolation sealing cold state simulation test system schematic diagram;

[0022] Figure 2 is a test body device structure schematic diagram;

[0023] Figure 3 is a replaceable pressure isolation sealing test piece schematic diagram. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] This invention provides a cold-state simulation test system and method for the pressure isolation and sealing of a multi-backpressure condenser. A visual test bench for the pressure isolation and sealing characteristics of a multi-backpressure condenser under cold-state conditions is designed and constructed. This bench allows for cold-state simulation tests, using pure water instead of condensate and air instead of steam. The system studies the leakage of air and water through the narrow gap between the condenser tubes and the pressure plate under different condensate supply methods, pressure isolation and sealing forms, and various operating pressure differentials. It also observes the flow and distribution of condensate at the inlet and outlet of the narrow gap under different conditions. The test results can be combined to analyze the impact of condensate flow rate, operating parameters, and pressure isolation and sealing forms on leakage, providing guidance for the design of multi-backpressure condensers.

[0026] like Figure 1 As shown, the test system mainly consists of three parts: an air supply system, a water supply system, and the test device body. The present invention is mainly composed of a water tank, a centrifugal water pump, a water mass flow meter, the test device body, a replaceable pressure-sealing test piece, an air compressor, a high-pressure gas tank, a gas flow meter, and connecting pipelines between them. Figure 1 The device includes: 1-Test body; 2-Exhaust valve; 3-Water supply regulating valve; 4-Mass flow meter; 5-Flow meter inlet valve; 6-Pump outlet valve; 7-Centrifugal water pump; 8-Pump inlet valve; 9-Bypass valve; 10-Water tank; 11-Air compressor; 12-Main gas switch; 13-Gas flow meter; 14-Inlet valve; 15-Exhaust valve; 16-Drain valve; 17-Drain valve; 18-Replaceable pressure-sealing test piece; 19-Gas tank; 20-Pressure measuring point 1; 21-Pressure measuring point 2.

[0027] During the test, the air compressor 11 in the gas supply system pumps air into the high-pressure gas tank 19 to ensure sufficient pressure in the tank. The large volume of the gas tank acts as a buffer, allowing for a relatively stable gas flow. The air flow is measured by the gas flow meter 13, and the pressure difference between the high and low pressure chambers is controlled by the inlet valve 14. The low-pressure chamber inlet valve 2 is connected to the atmosphere, while the high-pressure chamber exhaust valve 15 is closed. The predetermined test pressure is reached by inflation, thus establishing the pressure difference. The air leakage from the high-pressure chamber to the low-pressure chamber under different conditions is measured by the air mass flow meter 13. In the water supply system, the water tank 10 provides a stable water source for the water pump 7, providing a destination for bypass flow regulation. The centrifugal water pump 7 then provides power for a stable water supply to the high-pressure chamber. The water supply flow is measured by the mass flow meter 4, and a water supply regulating valve 3 is installed near the test device body to precisely regulate the water supply flow, thereby simulating condensation under different flow rates. The water supply temperature is monitored by a temperature measuring instrument. When the required water flow rate is low, the water supply system can be modified to consist of an injection pump, valves, and corresponding connecting pipelines to provide a small flow rate of water.

[0028] Schematic diagram of the main structure of the test deviceFigure 2 The body has two chambers, which are absolutely sealed between the opening and the atmosphere, so as to ensure that the gas entering the chamber can only be discharged through the replaceable pressure barrier sealing test of the narrow annular gap, ensuring the accurate measurement of leakage flow. The high and low pressure chambers are established by the air inlet and outlet, and these air inlets and outlets are left on the front of the test bench, which facilitates the installation and adjustment of the gas pipeline during the test. The high pressure chamber has a water inlet outside and an interface inside to connect the chamber to simulate condensate water. Water can be supplied by installing a nozzle on the water supply pipe and adjusting the installation angle, or by directly connecting a syringe needle to the water supply pipe and ensuring that the needle tip extends into the annular gap. At the same time, both chambers are provided with a drain, the high pressure chamber is drained to prevent excessive water accumulation in the chamber and submerge the narrow annular gap, and the low pressure chamber is always open to measure the water flow through the narrow annular gap by weighing method. In order to adjust and obtain the pressure value, pressure gauges are installed in both chambers.

[0029] Replaceable pressure barrier sealing test piece Figure 3 The test piece forms a narrow annular gap with the outer sleeve through a metal pipe. Figure 3 The right side is machined to a diameter that can tightly fit with the set diameter (the test diameter is 16mm) metal pipe, so that the metal pipe is supported and the concentricity of the metal pipe and the left narrow annular gap flow section is ensured, making the narrow annular gap uniform. After the two-phase mixture passes through the required flow section, two grooves are directly machined to quickly discharge the fluid, the upper groove is used to ensure gas discharge, and the lower groove is used to ensure liquid discharge. By machining the outer sleeve of the test piece, different sizes, different roughness or annular gap channel forms with different grooves can be obtained.

[0030] The test process is as follows:

[0031] 1. Pre-test preparation: open the flange cover of the high pressure chamber, correctly install the replaceable pressure barrier sealing test piece used in this test on the test body device partition, adjust the water supply mode in the high pressure chamber, install the water supply device correctly, then install the flange cover of the test body device, and connect the compressed air pipeline.

[0032] 2. Test start-up phase: start the air compressor, open the valves, close the air inlets and outlets of the two chambers, charge a certain amount of air into the two chambers, establish the set pressure, then close the valve to prevent the continued entry of gas. Maintain this state for 3-5 minutes, if the chamber can maintain the pressure unchanged, it is considered that the chamber is perfectly sealed and the test can continue. Open the low pressure chamber drain and air outlet, so that the low pressure chamber is reduced to atmospheric pressure and the pressure is maintained at atmospheric pressure during the test (if the test contains a water supply process, check the water supply pipeline at this time and open the centrifugal pump or syringe pump, then adjust the water flow to the test requirement and maintain it unchanged).

[0033] 3. Test phase: open the high pressure chamber inflation valve, adjust the inflation flow to make the high and low pressure chamber pressure difference to the test required data point, record the gas flow meter reading after the flow is stable. At this time, the narrow gap water flow is measured by weighing method at the low pressure chamber drain, and the mass of water passing through 90s is calculated. After the measurement of a pressure difference is completed, change to the next pressure difference for testing until all the set pressure differences are measured completely.

Claims

1. A multi-back pressure condenser pressure containment cold simulation test system, characterized in that: The test device body, a gas supply system, and a water supply system are included. The test device body includes a low-pressure chamber and a high-pressure chamber separated by a partition plate. The low-pressure chamber is provided with an exhaust port communicated with the atmosphere through an exhaust valve and a drain port connected with a drain valve. The high-pressure chamber is provided with a water supply port, a drain port connected with the drain valve, an air inlet port, and an exhaust port communicated with the atmosphere through the exhaust valve. The partition plate between the two chambers is provided with a replaceable pressure-sealing test piece. The high-pressure chamber is provided with a detachable end cover for replacing and installing the replaceable pressure-sealing test piece and adjusting the water supply mode. The replaceable pressure-sealing test piece includes a metal pipe and an outer pipe sleeve. The metal pipe penetrates through the partition plate, and the outer pipe sleeve is fixedly installed on the partition plate. The metal pipe and the outer pipe sleeve are tightly fitted at one end close to the partition plate to form a narrow annular gap, and at one end away from the partition plate on the same side. The water supply system includes a water pump, a water tank providing water source for the water pump, and a mass flow meter measuring water supply flow. The water tank is connected with the water pump through a pre-pump valve. The water pump is connected with the mass flow meter through a post-pump valve and a pre-flow meter valve in sequence. The mass flow meter is connected with the water supply port of the test device body through a water supply adjusting valve. A bypass valve is arranged between the pre-flow meter valve and the post-pump valve to return the bypass adjusting flow to the water tank. The gas supply system includes an air compressor, a gas tank storing buffer gas, and a gas flow meter measuring gas flow. The air compressor pumps air into the gas tank through a valve. The gas tank is connected with the high-pressure chamber air inlet port through a gas main switch, the gas flow meter, and an air inlet valve.

2. The multi-back pressure condenser pressure isolated sealing cold state simulation test system according to claim 1, characterized in that: Two grooves are arranged on the outer pipe sleeve.

3. The multi-back pressure condenser pressure isolated sealing cold state simulation test system according to claim 1, characterized in that: Pressure measuring points are arranged on the low-pressure chamber and the high-pressure chamber to obtain pressure values.

4. The multi-back pressure condenser pressure isolated sealing cold state simulation test system according to claim 1, characterized in that: The water pump is a centrifugal water pump or a syringe pump.

5. The multi-back pressure condenser pressure containment cold simulation test system of claim 1, wherein: A nozzle is installed on the water supply port in the high-pressure chamber, and the installation angle is adjusted to realize water supply or connect a syringe needle to ensure that the needle tip extends into the annular gap to realize water injection.

6. A method for cold state simulation test of pressure isolation of a multi-backpressure condenser, characterized in that: Any system of claims 1-5 is adopted, including: A. Pre-test preparation: open the end cover of the high-pressure chamber, install the replaceable pressure-sealing test piece on the partition plate of the test body, install the water supply device according to the water supply mode if the test includes a water supply process, then install the end cover, connect the gas supply system pipeline, and connect the water supply pipeline if the test includes a water supply process; B. Test start stage: start the air compressor, open the valves, close the air inlets of the two chambers of the test bench, fill air into the two chambers, set the pressure, close the valves, maintain the state for 3-5 min, and if the chamber can maintain the pressure unchanged, it is considered that the chamber sealing performance is good and the test can continue. Open the low-pressure chamber drain port and the air outlet to reduce the low-pressure chamber to atmospheric pressure and maintain the pressure at atmospheric pressure during the test. If the test includes a water supply process, check whether the water supply pipeline is normal and start the water pump, then adjust the water supply flow to the test requirement and maintain it unchanged; C. Test phase: Open the high pressure chamber inlet valve, adjust the flow to make the high and low pressure chamber differential to the test required data points, record the gas flow meter reading after the flow is stable, if the test contains water supply process, measure the narrow gap water flow at the low pressure chamber drain with weighing method, calculate the water quality for a given time, complete the measurement of a differential, change to the next differential for testing until all the set differentials are measured completely.

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