Water replenishing system for liquid level measurement balance container of pressure container of thermal power plant

Abstract

The utility model discloses a thermal power plant pressure vessel liquid level measurement balancing vessel water replenishing system which comprises at least one pressure vessel, a single-chamber balancing vessel, a single high-level water replenishing tank and a decentralized control system. The pressure container is communicated with the high-level water replenishing tank through a ventilation pipeline; the middle part and the lower part of the side wall of the pressure container are respectively connected to the single-chamber balance container through a first water pipeline and a second water pipeline, and a differential pressure transmitter is arranged on the second water pipeline; the single-chamber balancing container is connected to the high-level water replenishing tank through a third water pipeline; a sound-light alarm module is arranged in the distributed control system; a liquid level meter and a water replenishing valve are arranged on the high-level water replenishing tank, and the elevation of the high-level water replenishing tank is larger than that of the pressure container; a water replenishing electromagnetic valve is arranged on the third water pipeline; an electric contact liquid level switch is arranged on the single-chamber balance container, the liquid level in the single-chamber balance container is directly monitored through the electric contact liquid level switch, and when the liquid level is low, automatic water replenishing is achieved through a high-position water replenishing tank and a water replenishing electromagnetic valve.

Description

Technical Field

[0001] The utility model relates to the technical field of pressure vessel liquid level measurement, in particular to a pressure vessel liquid level measurement and balance vessel water replenishment system for a thermal power plant. Background Art

[0002] In industrial system design, liquid level measurement of pressure vessels is a common measurement scenario. Due to the characteristics of pressure vessels, their liquid level measurement is more important for equipment protection and system operation, and the reliability and accuracy of liquid level measurement are also required to be high.

[0003] The differential pressure measurement principle is the most classic pressure vessel level measurement principle, and is currently the most widely used in thermal power plants. The differential pressure measurement principle has high measurement accuracy (depending on the accuracy of the differential pressure transmitter, it can reach 0.075% or even higher). The measurement sampling system using a single-chamber balance container plus a pressure pipe can basically ignore the impact of high temperature in the container on the transmitter, and is not affected by the vibration of the container and the piping system. However, the differential pressure measurement principle also has the disadvantage of a more complex sampling system, and due to its measurement principle requirements, the reference water level in the balance container must be kept constant, so the balance container must be replenished to the overflow water level in advance at the beginning of the system startup. During operation, the water level in the balance container is replenished and maintained constant by water vapor condensation and overflow. However, if the flash phenomenon occurs due to a sudden loss of pressure in the container due to changes in operating conditions, the liquid in the balance container will evaporate instantly, causing the reference water level to drop suddenly. It will take a long time to replenish the water level by natural condensation. During this period of time when the reference water level changes, the liquid level measurement of the pressure vessel will show a false low water level or even zero water level.

[0004] Therefore, it is urgent to propose a new solution to solve the above problems. Summary of the invention

[0005] The utility model provides a water replenishing system for a pressure vessel liquid level measurement and a balancing vessel in a thermal power plant, which can solve the problem of inaccurate liquid level measurement of the existing pressure vessel.

[0006] The utility model provides a thermal power plant pressure vessel liquid level measurement balance vessel water replenishment system, comprising at least one pressure vessel and a single-chamber balance vessel, a single high-level water replenishment tank and a distributed control system;

[0007] The pressure vessel is connected to the high-position water supply tank through a ventilation pipeline;

[0008] The middle and lower parts of the side wall of the pressure vessel are connected to the single-chamber balance container through a first water pipeline and a second water pipeline respectively, and a differential pressure transmitter is arranged on the second water pipeline;

[0009] The single-chamber balancing container is connected to the high-position water replenishment tank through a third water pipeline;

[0010] The distributed control system is provided with an audible and visual alarm module;

[0011] The high-position water supply tank is provided with a liquid level gauge and a water supply valve, and the elevation of the high-position water supply tank is greater than the elevation of the pressure vessel;

[0012] The third water pipeline is provided with a water replenishment solenoid valve;

[0013] The single-chamber balancing container is provided with an electric contact liquid level switch;

[0014] The electric contact liquid level switch, liquid level meter, water supply valve, water supply solenoid valve and differential pressure transmitter are all connected to the distributed control system through signal cables.

[0015] Furthermore, the liquid level meter is a magnetic flap liquid level meter with a remote signal interface.

[0016] Furthermore, a first stop valve and a second stop valve are respectively provided on the left and right sides of the water replenishment solenoid valve.

[0017] Furthermore, the sizes of the first stop valve and the second stop valve are DN6-DN10.

[0018] Furthermore, the electric contact liquid level switch comprises an electrode, a wire and an electric contact secondary display meter, and the electrode is mounted on the side wall of the single-chamber balancing container in a detachable connection manner.

[0019] Furthermore, the electrode is installed at a position lower than the connection between the first water pipeline and the single-chamber balancing container.

[0020] Furthermore, an overflow balancing valve is provided on the ventilation pipeline.

[0021] Furthermore, the ventilation pipeline and the high-position water supply tank are both provided with thermal insulation materials.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] 1. The utility model adopts a single-chamber balancing container with an electric contact liquid level switch, and the electric contact liquid level switch is resistant to high temperature and high pressure. The water level in the single-chamber balancing container is monitored in real time by the electric contact liquid level switch, and the liquid level height in the pressure vessel is indirectly measured by measuring the pressure difference between the liquid levels in the single-chamber balancing container and the pressure vessel, and the water level signal is transmitted to the distributed control system in time. Once the water level in the single-chamber balancing container drops abnormally, the sound and light alarm module in the distributed control system will be triggered, and the operator can immediately find and take measures. At the same time, the preset sequential control logic can be started to automatically replenish water, or the operator can remotely control the replenishment of water through the water replenishment solenoid valve. The liquid level switch state can also be intuitively monitored on site through the alarm light on the secondary meter of the electric contact liquid level switch;

[0024] 2. The utility model provides a single high-position water replenishment tank to meet the water replenishment needs of all balancing containers in the system. The high-position water replenishment tank is connected to the pressure vessel through a ventilation pipeline to ensure that the pressures of the two are the same. Pressurized water replenishment is achieved through the pressure in the pressure vessel, without the need to provide a separate high-pressure water replenishment pump or to connect a high-pressure water replenishment source to each single-chamber balancing container;

[0025] 3. When the electric contact secondary display meter of the electric contact liquid level switch of the utility model shows that the liquid level in the single-chamber balance container is low, the water replenishment solenoid valve is opened to automatically replenish water by controlling the distributed control system, which greatly reduces the workload of manual water replenishment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a water replenishment system for a pressure vessel liquid level measurement and a balance vessel in a thermal power plant according to the utility model;

[0027] Figure numerals: 1. pressure vessel; 2. high-level water supply tank; 21. liquid level gauge; 22. water supply valve; 3. single-chamber balancing container; 31. electric contact liquid level switch; 311. electrode; 312. wire; 313. electric contact secondary display meter; 4. distributed control system; 41. sound and light alarm module; 51. first water supply pipeline; 52. second water supply pipeline; 53. third water supply pipeline; 6. differential pressure transmitter; 71. water supply solenoid valve; 72. first stop valve; 73. second stop valve; 8. ventilation pipeline; 81. overflow balancing valve. DETAILED DESCRIPTION

[0028] In order to further understand the content, features and functions of the utility model, the following embodiments are given, together with the attached Figure 1 The detailed instructions are as follows.

[0029] like Figure 1 As shown, the utility model provides a thermal power plant pressure vessel liquid level measurement balance vessel water replenishment system, comprising at least one pressure vessel 1 and a single-chamber balance vessel 3, a single high-level water replenishment tank 2 and a distributed control system 4;

[0030] The pressure vessel 1 is connected to the high-level water supply tank 2 through a ventilation pipeline 8;

[0031] The middle and lower parts of the side wall of the pressure vessel 1 are connected to the single-chamber balance container 3 through the first water pipeline 51 and the second water pipeline 52 respectively, and the second water pipeline 52 is provided with a differential pressure transmitter 6;

[0032] The above-mentioned single-chamber balancing container 3 is connected to the high-level water supply tank 2 through the third water pipeline 53;

[0033] The above-mentioned distributed control system 4 is provided with an audible and visual alarm module 41;

[0034] The high-level water supply tank 2 is provided with a liquid level gauge 21 and a water supply valve 22, wherein the water supply valve 22 is manually controlled. The elevation of the high-level water supply tank 2 is greater than the elevation of the pressure vessel 1, and a single high-level water supply tank 2 can be connected to multiple balancing vessels;

[0035] The third water pipe 53 is provided with a water supply solenoid valve 71;

[0036] The above-mentioned single-chamber balance container 3 is provided with an electric contact liquid level switch 31;

[0037] The above-mentioned electric contact liquid level switch 31, liquid level meter 21, water replenishment solenoid valve 71 and differential pressure transmitter 6 are all connected to the distributed control system 4 through a signal cable (not shown in the figure).

[0038] The utility model adopts a single-chamber balancing container with an electric contact liquid level switch, and the electric contact liquid level switch is resistant to high temperature and high pressure. The water level in the single-chamber balancing container is monitored in real time by the electric contact liquid level switch, and the liquid level height in the pressure vessel is indirectly measured by measuring the pressure difference between the liquid levels in the single-chamber balancing container and the pressure vessel, and the water level signal is transmitted to the distributed control system in time. Once the water level in the single-chamber balancing container drops abnormally, the sound and light alarm module in the distributed control system will be triggered, and the operator can immediately find and take measures. At the same time, the preset sequential control logic can be started to automatically replenish water, or the operator can remotely control the replenishment of water through the replenishment solenoid valve. The liquid level switch state can also be intuitively monitored on site through the alarm light on the secondary meter of the electric contact liquid level switch; in addition, a single high-level replenishment water tank is set to meet the replenishment needs of all balancing containers in the system. The high-level replenishment water tank is connected to the pressure vessel through a ventilation pipeline to ensure that the pressures of the two are the same, and pressurized replenishment is achieved through the pressure in the pressure vessel, without the need to set a separate high-pressure replenishment water pump or connect a high-pressure replenishment water source to each single-chamber balancing container. Moreover, the detection principle of the electric contact liquid level switch is direct measurement, which avoids complex compensation calculations.

[0039] In this embodiment, the elevation of the installation position of the above-mentioned first water pipeline 51 is greater than the liquid level of the pressure vessel 1, and the elevation of the installation position of the above-mentioned first water pipeline 52 is less than the liquid level of the pressure vessel 1. This makes it convenient to set up the differential pressure transmitter 6. In addition, the high-level water supply tank 2 should be designed according to the same level of pressure resistance as the pressure vessel 1.

[0040] In this embodiment, the liquid level meter 21 is a magnetic flap liquid level meter with a remote signal interface, which is more convenient and simple and can meet the accuracy requirements.

[0041] In this embodiment, Figure 1 As shown, the first stop valve 72 and the second stop valve 73 are respectively provided on the left and right sides of the above-mentioned water replenishment solenoid valve 71. When the water replenishment solenoid valve 71 fails and needs to be repaired or when the high-level water replenishment tank 2 needs to be replenished with water, the first stop valve 72 and the second stop valve 73 can be manually closed. In addition, the first stop valve 72 and the second stop valve 73 can also be directly connected to the distributed control system 4 through a signal cable.

[0042] In this embodiment, the sizes of the first stop valve 72 and the second stop valve 73 are both DN8, and other values ​​between DN6 and DN10 may also be used.

[0043] In this embodiment, Figure 1 As shown, the electric contact liquid level switch 31 includes an electrode 311, a wire 312 and an electric contact secondary display meter 313. The electrode 311 is installed on the side wall of the single-chamber balancing container 3 by a detachable connection method such as a bolt threaded connection. Its installation position should be slightly lower than the overflow port height. The overflow port is the connection between the first water pipeline 51 and the single-chamber balancing container 3 to ensure that the electric contact liquid level switch 31 can detect the water level when the single-chamber balancing container 3 is at a normal water level. Each high-level water replenishment tank 2 can be used to replenish water to multiple balancing containers with similar pressures in the same system at the same time. Before starting the unit or the entire system, fill the water replenishment tank with water to the full water level in advance. When the electric contact secondary display meter 313 of the electric contact liquid level switch 31 shows that the liquid level in the single-chamber balancing container 3 is low, the distributed control system 4 is controlled to open the water replenishment solenoid valve 71 to automatically replenish water, greatly reducing the workload of manual water replenishment.

[0044] In this embodiment, Figure 1 As shown, the ventilation pipeline 8 is provided with an overflow balancing valve 81, and the overflow balancing valve 81 is manually controlled. The magnetic flap level gauge with a remote signal interface on the high-level water supply tank 2 is connected to the control system 4 through a signal cable. During operation, regular inspections should be carried out to observe the magnetic flap level gauge on the high-level water supply tank 2. When the water level is low, the sound and light alarm module 41 sends out a sound and light alarm signal to remind the operating personnel to deal with it in time. The overflow balancing valve 81, the first stop valve 72 and the second stop valve 73 should be closed in time, and the water supply valve 22 should be opened manually to replenish water to the high-level water supply tank 2 to the full water level.

[0045] In this embodiment, the ventilation pipeline 8 and the high-position water supply tank 2 are both provided with heat-insulating materials to achieve a heat-insulating effect.

[0046] The utility model described above in the present invention only expresses the implementation method of the utility model embodiment, and cannot be understood as limiting the scope of the utility model patent, nor is it any form of limitation on the structure of the utility model embodiment. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the utility model embodiment, several changes and improvements can be made, which all belong to the protection scope of the utility model embodiment.

Claims

1. A water replenishment system for pressure vessel liquid level measurement and balance vessel in a thermal power plant, characterized by: It comprises at least one pressure vessel (1) and a single-chamber balance vessel (3), a single high-level water replenishment tank (2) and a distributed control system (4); The pressure container (1) is connected to the high-position water supply tank (2) via a ventilation pipeline (8); The middle and lower parts of the side wall of the pressure vessel (1) are connected to the single-chamber balance vessel (3) through a first water pipeline (51) and a second water pipeline (52), respectively, and a differential pressure transmitter (6) is provided on the second water pipeline (52); The single-chamber balancing container (3) is connected to the high-position water replenishment tank (2) via a third water pipeline (53); The distributed control system (4) is provided with an audible and visual alarm module (41); The high-position water supply tank (2) is provided with a liquid level meter (21) and a water supply valve (22), and the elevation of the high-position water supply tank (2) is greater than the elevation of the pressure vessel (1); The third water pipeline (53) is provided with a water replenishment solenoid valve (71); The single-chamber balancing container (3) is provided with an electric contact liquid level switch (31); The electric contact liquid level switch (31), the liquid level meter (21), the water replenishment solenoid valve (71) and the differential pressure transmitter (6) are all connected to the distributed control system (4) via signal cables.

2. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 1, characterized in that: The liquid level meter (21) is a magnetic flap liquid level meter with a remote signal transmission interface.

3. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 1, characterized in that: A first stop valve (72) and a second stop valve (73) are respectively arranged on the left and right sides of the water replenishment solenoid valve (71).

4. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 3, characterized in that: The sizes of the first stop valve (72) and the second stop valve (73) are DN6-DN10.

5. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 1, characterized in that: The electric contact liquid level switch (31) comprises an electrode (311), a wire (312) and an electric contact secondary display meter (313); the electrode (311) is mounted on the side wall of the single-chamber balancing container (3) in a detachable connection manner.

6. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 5, characterized in that: The electrode (311) is installed at a position lower than the connection between the first water pipeline (51) and the single-chamber balancing container (3).

7. A thermal power plant pressure vessel liquid level measurement and balance vessel water replenishment system according to claim 1, characterized in that: The ventilation pipeline (8) is provided with an overflow balancing valve (81).

8. The system for measuring the liquid level of a pressure vessel in a thermal power plant and replenishing the balance vessel according to claim 1 is characterized by: The ventilation pipeline (8) and the high-position water replenishment tank (2) are both provided with heat-insulating materials.

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