High inlet salt water pipe safety device

Abstract

The utility model belongs to the high pressure feedwater system safety technical field of thermal power generation, concretely relates to a high inlet desalted water pipeline safety device, including high inlet desalted water pipeline, pressure remote measuring point, two check valves and a check valve are equipped in proper order on high inlet desalted water pipeline along medium flow direction, and drain valve is set up on the pipeline between a check valve and two check valves. The utility model is the safety device of high inlet desalted water pipeline anti -overpressure and anti -backflow based on pressure sensor and interlock control, and the safety reliability is improved obviously through the redundancy design of initiative and passive combination.

Description

Technical Field

[0001] This utility model belongs to the field of safety technology for high-pressure water supply systems in thermal power generation, specifically relating to a safety device for a high-pressure demineralized water pipeline. Background Technology

[0002] In thermal power plants, high-pressure heaters (HPUs) are crucial equipment for heating boiler feedwater using steam extracted from the turbine. Their inlet connects to the demineralized water pipeline. Under normal operating conditions, the HPU system withstands high-pressure feedwater, with the inlet pressure reaching up to 39.3 MPa. If the valves are not tight, high-pressure water backflow can cause severe overpressure in the demineralized water system. Since the demineralized water pipeline is a low-pressure pipeline, overpressure could lead to explosions, damaging equipment and even causing personal injury.

[0003] Therefore, there is an urgent need to develop and design a safety device for high-inlet demineralized water pipelines that is faster-responding, more reliable, and can effectively prevent failure. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a safety device for preventing overpressure and backflow in high-inlet demineralized water pipelines based on pressure sensing and interlocking control. Through a redundant design that combines active and passive features, the device significantly improves safety and reliability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A safety device for a high-inlet demineralized water pipeline includes a high-inlet demineralized water pipeline, wherein a pressure remote measuring point, two check valves and one check valve are sequentially arranged along the medium flow direction on the high-inlet demineralized water pipeline, and a drain valve is installed on the pipeline between the first check valve and the second check valve. The aforementioned check valve is a mechanical, high-strength check valve located near the high-pressure side, used to withstand the pressure difference between the two sides during normal operation through its mechanical structure. The high-pressure side is located near the high-pressure inlet.

[0006] The second non-return valve is an interlocked non-return valve located on the low-pressure side of the first non-return valve. This interlocked non-return valve has two closing modes: first, it closes automatically using the force of reverse liquid flow; second, it closes forcibly using a pneumatic or electric actuator driven by receiving an external control signal. The control signal is a pressure rise signal detected by a remote pressure measuring point.

[0007] The pressure remote sensing point is a pressure sensor (PT). The pressure sensor signal is transmitted to the distributed control system (DCS) for real-time monitoring of the pressure in the pipe section.

[0008] The DCS is configured to receive signals from pressure measuring points PT and execute differential pressure / constant pressure judgment logic: when the pressure reaches the first set value (constant pressure mode), or when the pressure rise rate exceeds the second set value (differential pressure / rate mode), the DCS outputs an interlock control signal; the interlock control signal is simultaneously sent to the forced closing actuators of the two check valves and the related drain valves and feedwater pump speed control mechanisms.

[0009] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. This utility model achieves dual redundancy, avoiding common-cause failure. In this utility model, the first check valve is a normally closed mechanical door, bearing the main pressure difference; the second check valve is in a free state during normal operation, only actuating in abnormal situations. Their working principles and stress states differ; the first check valve bears static high pressure, while the second check valve serves as a dynamic backup, effectively avoiding common-cause failure problems such as adhesion and jamming caused by long-term identical operating conditions (such as high-pressure scouring).

[0010] 2. This utility model can provide proactive early warning and intervention. By introducing the pressure rise rate (differential pressure mode) as a judgment criterion, the system can trigger protective actions in advance when the absolute pressure value has not yet reached the danger value but has already shown a rapid upward trend.

[0011] 3. The safety protection actions of this utility model not only include closing the two check valves, but also interlocking to open the drain valve to release pressure and reduce the speed of the feed water pump to reduce the pressure source from the source, which greatly reduces the risk of overpressure in the demineralized water pipeline. Attached Figure Description

[0012] Figure 1 This is a structural schematic diagram of the safety device of this utility model; Figure label: 1. High-pressure demineralized water inlet pipe; 2. First check valve; 3. Second check valve; 4. Pressure remote transmission measuring point; 5. Drainage valve. Detailed Implementation

[0013] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1 As shown, a safety device for a high-inlet demineralized water pipeline includes a high-inlet demineralized water pipeline 1. The high-inlet demineralized water pipeline 1 is provided with a pressure remote measuring point 4, two check valves 3 and one check valve 2 in sequence along the medium flow direction. A drain valve 5 is installed on the pipeline between the one check valve 2 and the two check valves 3.

[0015] The drain valve in this embodiment includes two drain pressure relief valves connected in series. The first drain pressure relief valve may leak due to frequent operation, and the second drain pressure relief valve ensures that there will be no leakage when the first drain pressure relief valve leaks.

[0016] The safety device of this utility model is installed on the high-inlet demineralized water pipeline 1. The normal flow direction of the medium is from right to left (e.g., Figure 1 (As shown by the red arrow in the middle), it flows to the high-pressure heater. Near the high-pressure side, there is a check valve 2, which is a purely mechanical structure with high design strength, used to isolate the high pressure during steady-state operation.

[0017] On the low-pressure side of the first check valve 2, two check valves 3 are installed. These two check valves 3 are interlocked and have integrated pneumatic (or electric) actuators. During fault-free operation, their valve discs can swing freely with minimal impact on flow resistance. When emergency closure is required, they can be forced to close either by the backflow of fluid or by a signal from the distributed control system (DCS) driving the actuators.

[0018] In this embodiment, the pressure remote sensing point 4 uses a pressure transmitter conventionally used in the field. The pressure signal from this sensing point is transmitted to the DCS in real time. In this embodiment, a general-purpose DCS for high-pressure water supply systems in thermal power plants can be used. The connection between this DCS and the check valve, pressure sensing point PT, and drain valve is not detailed in the provided text. Figure 1 As shown in the figure. The check valve, pressure measuring point PT, and drain valve involved in this embodiment are all conventional devices in the art, which can achieve their functions.

[0019] In this embodiment, the pressure remote sensing point 4 is set in front of the second check valve 3. When the first check valve 2 leaks, the pressure sensing point PT detects the pressure increase and triggers the interlocking check valve to close the second check valve 3 to prevent high-pressure water from flowing back into the low-pressure pipeline. At the same time, the drain valve is opened and the speed of the water pump is reduced.

[0020] In practical use, a higher pressure threshold P can be set. 高 When the pressure value detected by the pressure transmission point 4 is ≥ P 高 When the pressure rise rate exceeds dP / dt_max, an action is triggered. A pressure rise rate threshold dP / dt_max can also be set. The DCS continuously calculates the pressure change per unit time. Even if the current absolute pressure value is not high, if its rise rate exceeds dP / dt_max, it is considered to have a risk of sudden overpressure (such as turbine load shedding), and an action is immediately triggered.

[0021] When any of the above conditions are met, the DCS sends the following interlock control signals: a forced closing signal to the actuator of the second check valve 3; an opening signal to the drain valve to relieve pressure; and a command to the feedwater pump speed controller to reduce the feedwater pump speed, thereby reducing the water supply pressure and flow rate at the source.

[0022] This invention features a pressure measuring point (PT) that transmits data to a DCS screen along with two check valves on the high-pressure inlet demineralized water pipeline. The check valve closer to the high-pressure side is a mechanical, high-strength check valve, which resists the pressure difference between the two sides during normal operation. Two interlocking check valves are added to the low-pressure side of the first check valve. These interlocking check valves differ from traditional check valves; they can automatically close using the force of reverse liquid flow, or be forcibly closed by pneumatic action triggered by a pressure sensor signal, thus improving the reliability of the check valve operation. When the first check valve leaks, the pressure measuring point (PT) detects the increased pressure and automatically triggers the interlocking check valves, preventing high-pressure water from flowing back into the low-pressure pipeline. Since the first check valve is normally closed while the second check valve is freely movable, this redundant arrangement effectively avoids the failure of both check valves due to adhesion and jamming caused by long-term high-pressure scouring and compression of the first check valve. Furthermore, this pressure measuring point (PT) adopts a differential pressure control mode, which can activate when the pressure reaches a certain set value, and also trigger the closure of two check valves, the opening of the drain valve, and the reduction of the feed water pump speed even if the set value is not reached, but the rate of pressure rise reaches the set value. These multiple safeguards ensure that the demineralized water pipeline does not become overpressured. This invention facilitates monitoring pressure changes in the high-pressure feed inlet demineralized water pipeline. Once a pressure increase or an excessively rapid rate of pressure rise is detected, backflow in the high-pressure and low-pressure water supply pipelines can be confirmed, allowing for appropriate measures to prevent overpressure accidents in the high-pressure and low-pressure water supply pipelines.

[0023] For any content not described in detail in this utility model, conventional technical knowledge in the field can be used.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solution of this utility model do not depart from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A safety device for a high-inlet demineralized water pipeline, comprising a high-inlet demineralized water pipeline, characterized in that, The high-pressure inlet demineralized water pipeline is equipped with a pressure remote measuring point, two check valves and one check valve in sequence along the medium flow direction, and a drain valve is installed on the pipeline between the first check valve and the second check valve.

2. The safety device for high-inlet demineralized water pipeline according to claim 1, characterized in that, The drain valve includes two drain pressure relief valves connected in series.

3. The safety device for the high-inlet demineralized water pipeline according to claim 1, characterized in that, The first non-return valve is a mechanical high-strength non-return valve located near the high-pressure side, used to resist the pressure difference between the two sides by relying on its mechanical structure during normal operation; the second non-return valve is an interlocking non-return valve installed on the low-pressure side of the first non-return valve.

4. The safety device for high-inlet demineralized water pipeline according to claim 1, characterized in that, The pressure remote transmission measurement point is a pressure measurement point PT, and the pressure measurement point PT signal is transmitted to the distributed control system DCS.

5. The safety device for high-inlet demineralized water pipeline according to claim 4, characterized in that, The pressure measuring point PT is a pressure transmitter.

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