A control system for regulating valve opening under high static pressure difference

Abstract

The invention discloses a control system for opening a regulating valve under a high static pressure difference state, which belongs to the technical field of industrial high static pressure difference valve control, and in particular to the field of automatic control of regulating valves in high static pressure difference pipelines of power plants, including a regulating valve, an electric stop valve and a DCS control device, wherein the regulating valve is provided with an electric stop valve on a pipeline in the direction of medium inflow, a differential pressure transmitter is connected to the pipelines at the front and rear ends of the regulating valve, and a bypass pipe is led out from the pipelines at the front and rear ends of the regulating valve, and a manual stop valve and an electromagnetic ball valve are sequentially installed on the bypass pipe according to the flow direction of the medium; the regulating valve, the electric stop valve, the differential pressure transmitter and the electromagnetic ball valve are all connected to the remote DCS control device signal. The invention has the characteristics of simple structure, flexible control mode, and complete remote automatic control, and solves the problem that the regulating valve is difficult to open under a high static pressure state.

Description

Technical Field

[0001] The invention relates to a regulating valve opening control system under a high static pressure difference state, belonging to the technical field of industrial high static pressure difference valve control, in particular to the field of automatic control of high static pressure difference pipeline regulating valves in power plants. Background Art

[0002] With the continuous improvement of operating parameters, more and more regulating valves are under high static pressure difference in the production process of thermal power plants. Take the 361 regulating valve of the boiler of a supercritical unit of a coal-fired power plant as an example. During normal operation, the regulating valve is fully closed, and the static pressure difference before and after the valve core can reach 42MPa. When the unit trips due to a fault, the regulating valve needs to be opened in time, but due to the high static pressure difference before and after the valve, the valve is difficult to open in time, posing a threat to the safe operation of the unit.

[0003] The Chinese patent with publication number CN 202812357 U disclosed the "pressure differential balancing valve" on March 20, 2013. The technical solution is mainly to set the pressure difference between the upstream medium and the downstream medium when the valve is opened by the pressure setting screw at the top of the pressure differential balancing valve. When the pressure difference is greater than the set value, the pilot valve opens and then the main valve opens. The Chinese patent with publication number CN 210291838U disclosed "a system for effectively slowing down the leakage of the recirculation regulating valve in the water supply system" on April 10, 2020. The main solution is to add an electric valve in front of the regulating valve to slow down the static pressure difference of the regulating valve core, and transfer the static pressure difference originally borne by the regulating valve to the front electric door. The Chinese patent application with publication number CN110454596A disclosed "a piston-type dynamic pressure differential balancing valve" on November 15, 2019. The technical solution mainly includes a main valve and a pilot valve. The pilot valve is used to control the opening of the main valve to achieve the stability of the pressure difference of the controlled system.

[0004] In general, the current technical solutions mainly use a mechanical spring to control the opening of the pilot valve or transfer the static pressure difference borne by the regulating valve to the electric stop valve. There are problems such as complex mechanical structure of the valve system, inflexible pressure setting, and poor actual application effect on site. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a regulating valve opening control system under high static pressure difference conditions which has reasonable design, simple structure and reliable automatic control.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: a control system for opening a regulating valve under a high static pressure difference state, comprising a regulating valve, an electric stop valve and a DCS control device, wherein the regulating valve is provided with an electric stop valve on a pipeline in the direction of medium inflow, a differential pressure transmitter is connected to the pipelines at the front and rear ends of the regulating valve, and a bypass pipe is led out from the pipelines at the front and rear ends of the regulating valve, and a manual stop valve and an electromagnetic ball valve are sequentially installed on the bypass pipe according to the flow direction of the medium; the regulating valve, the electric stop valve, the differential pressure transmitter and the electromagnetic ball valve are all connected to the remote DCS control device signal.

[0007] Furthermore, the inner diameters of the bypass pipe, manual stop valve and electromagnetic ball valve are generally 1 / 5 to 1 / 10 of the diameter of the main pipeline of the regulating valve. The specific data are obtained by referring to the maximum safe static pressure of the regulating valve pipeline and taking into account factors such as the diameter of the main pipeline of the regulating valve and the manufacturing material and performing mechanical and thermal calculations.

[0008] Furthermore, the material of the bypass pipe, manual stop valve and electromagnetic ball valve should be consistent with the material of the pipe at the front end of the regulating valve to prevent the low-quality pipe behind the valve from bursting due to strong erosion by high-temperature and high-pressure media after the valve is suddenly opened.

[0009] Furthermore, when the regulating valve is normally operated, it is fully closed and the electric stop valve is fully open. The differential pressure value measured by the differential pressure transmitter is the high static pressure difference before and after the valve core of the regulating valve. The regulating valve can be inspected and maintained when the electric stop valve is closed.

[0010] Furthermore, the electromagnetic ball valve is fully closed during normal operation and the manual stop valve is fully open; the electromagnetic ball valve can be inspected and repaired when the manual stop valve is closed.

[0011] Furthermore, when the static pressure difference before and after the regulating valve measured by the differential pressure transmitter is not high, the electromagnetic ball valve will not open and the regulating valve can open autonomously; when the pressure difference before and after the regulating valve measured by the differential pressure transmitter is higher than the set value and the regulating valve needs to be opened, the electromagnetic ball valve will open first to balance a part of the static pressure difference before and after the regulating valve until the differential pressure value measured by the differential pressure transmitter is lower than the set value or after a certain delay, the regulating valve starts to open.

[0012] Furthermore, the setting value for opening the electromagnetic ball valve is the static pressure difference before and after the valve that can normally open the regulating valve during operation obtained from actual tests.

[0013] Furthermore, the control logic algorithm of the electromagnetic ball valve is set in the DCS control device; its basic logic condition is: when the static pressure difference of the pipeline measured by the differential pressure transmitter reaches a fixed value and the regulating valve needs to be opened or when the operator operates remotely, it is opened.

[0014] Compared with the prior art, the present invention has the following advantages and effects: the present invention adopts the scheme of installing a controllable bypass valve before and after the regulating valve to partially balance the pressure difference before and after the regulating valve, which solves the practical problem that the regulating valve is difficult to open under high static pressure. It has the characteristics of simple structure, flexible control mode, and complete remote automatic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an existing high static pressure difference regulating valve pipeline system.

[0016] Figure 2 It is a structural schematic diagram of the improved regulating valve opening control system under high static pressure difference state of the present invention.

[0017] In the figure: regulating valve 1, electric stop valve 2, differential pressure transmitter 3, bypass pipe 4, manual stop valve 5, electromagnetic ball valve 6, DCS control equipment 7. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0019] See also Figure 1 to Figure 2 A control system for opening a regulating valve under a high static pressure difference state comprises a regulating valve 1, an electric stop valve 2 and a DCS control device 7. The regulating valve 1 is provided with the electric stop valve 2 on a pipeline in the direction of medium inflow, a differential pressure transmitter 3 is connected to the pipelines at the front and rear ends of the regulating valve 1, and a bypass pipe 4 is led out from the pipelines at the front and rear ends of the regulating valve 1, and a manual stop valve 5 and an electromagnetic ball valve 6 are sequentially installed on the bypass pipe 4 according to the flow direction of the medium; the regulating valve 1, the electric stop valve 2, the differential pressure transmitter 3 and the electromagnetic ball valve 6 are all connected to the remote DCS control device 7 by signal.

[0020] Specifically, the inner diameters of the bypass pipe 4, the manual stop valve 5 and the electromagnetic ball valve 6 are generally 1 / 5 to 1 / 10 of the diameter of the main pipeline of the regulating valve 1. The specific data refer to the maximum safe static pressure of the pipeline of the regulating valve 1, and are obtained after mechanical and thermal calculations taking into account factors such as the diameter of the main pipeline of the regulating valve 1 and the manufacturing material.

[0021] Specifically, the material of the bypass pipe 4, the manual stop valve 5 and the electromagnetic ball valve 6 should be consistent with the material of the pipe at the front end of the regulating valve 1 to prevent the high-temperature and high-pressure medium from strongly flushing and causing the low-quality pipe behind the valve to burst after the valve is suddenly opened.

[0022] Specifically, when the regulating valve 1 is in normal operation, it is fully closed and the electric stop valve 2 is fully open. The differential pressure value measured by the differential pressure transmitter 3 is the high static pressure difference before and after the valve core of the regulating valve 1; when the electric stop valve 2 is closed, the regulating valve 1 can be inspected and repaired.

[0023] Specifically, the electromagnetic ball valve 6 is fully closed during normal operation, and the manual stop valve 5 is fully open; the electromagnetic ball valve 6 can be inspected and repaired when the manual stop valve 5 is closed.

[0024] Specifically, when the static pressure difference before and after the regulating valve 1 measured by the differential pressure transmitter 3 is not high, the electromagnetic ball valve 6 will not open, and the regulating valve 1 can open autonomously; when the pressure difference before and after the regulating valve 1 measured by the differential pressure transmitter 3 is higher than the set value and the regulating valve 1 needs to be opened, the electromagnetic ball valve 6 will open first to balance a part of the static pressure difference before and after the regulating valve 1, until the differential pressure value measured by the differential pressure transmitter 3 is lower than the set value (or after a certain delay), and the regulating valve 1 starts to open.

[0025] Specifically, the setting value for opening the electromagnetic ball valve 6 is the static pressure difference before and after the valve that can normally open the regulating valve 1 during operation obtained from actual tests.

[0026] Specifically, the control logic algorithm of the electromagnetic ball valve 6 is set in the DCS control device 7; its basic logic condition is: when the pipeline static pressure difference measured by the differential pressure transmitter 3 reaches a fixed value and the regulating valve 1 needs to be opened or when the operator operates remotely, it is opened.

[0027] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0028] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the protection scope of the present invention. Any changes and modifications made by any technician familiar with the technology without departing from the concept and scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A control system for opening a regulating valve under a high static pressure difference state, comprising a regulating valve (1), an electric stop valve (2) and a DCS control device (7), wherein: The regulating valve (1) is provided with an electric stop valve (2) on the pipeline in the direction of medium inflow; the pipelines at the front and rear ends of the regulating valve (1) are connected with a differential pressure transmitter (3); and a bypass pipe (4) is led out from the pipelines at the front and rear ends of the regulating valve (1); a manual stop valve (5) and an electromagnetic ball valve (6) are installed on the bypass pipe (4) in sequence according to the flow direction of the medium; the regulating valve (1), the electric stop valve (2), the differential pressure transmitter (3) and the electromagnetic ball valve (6) are all connected to a remote DCS control device (7) by signal; The inner diameters of the bypass pipe (4), the manual stop valve (5) and the electromagnetic ball valve (6) are 1 / 5 to 1 / 10 of the diameter of the main pipe of the regulating valve (1); When the regulating valve (1) is in normal operation, it is fully closed and the electric stop valve (2) is fully open. The differential pressure value measured by the differential pressure transmitter (3) is the high static pressure difference before and after the valve core of the regulating valve (1); when the electric stop valve (2) is closed, the regulating valve (1) can be inspected and repaired; The electromagnetic ball valve (6) is fully closed during normal operation and the manual stop valve (5) is fully open; the electromagnetic ball valve (6) can be inspected and repaired when the manual stop valve (5) is closed; When the static pressure difference before and after the regulating valve (1) measured by the differential pressure transmitter (3) is not high, the electromagnetic ball valve (6) does not open, and the regulating valve (1) can open autonomously; when the pressure difference before and after the regulating valve (1) measured by the differential pressure transmitter (3) is higher than the set value and the regulating valve (1) needs to be opened, the electromagnetic ball valve (6) opens first to balance a part of the static pressure difference before and after the regulating valve (1), until the differential pressure value measured by the differential pressure transmitter (3) is lower than the set value or after a certain delay, the regulating valve (1) starts to open; The setting value for opening the electromagnetic ball valve (6) is the static pressure difference before and after the valve that can normally open the regulating valve (1) during operation obtained in actual tests.

2. The regulating valve opening control system under high static pressure difference state according to claim 1, characterized in that: The material of the bypass pipe (4), the manual stop valve (5) and the electromagnetic ball valve (6) is consistent with the material of the pipe at the front end of the regulating valve (1).

3. The regulating valve opening control system under high static pressure difference state according to claim 1, characterized in that: The control logic algorithm of the electromagnetic ball valve (6) is set in the DCS control device (7); its basic logic condition is: when the static pressure difference of the pipeline measured by the differential pressure transmitter (3) reaches a fixed value and the regulating valve (1) needs to be opened or when the operator operates remotely, it is opened.

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