Online backwashing device for filter screen at outlet of condensate pump of thermal power plant

Abstract

The application relates to a power plant condensate water conveying system technical field, in particular to a power plant condensate water pump outlet filter screen online backwashing device, which comprises an A branch formed by an A condensate water pump and an A filter screen in series, a B branch formed by a B condensate water pump and a B filter screen in series, and a first backwashing pipeline and a second backwashing pipeline; wherein the first backwashing pipeline is used for backwashing the A filter screen through outlet water of the B condensate water pump; the second backwashing pipeline is used for backwashing the B filter screen through outlet water of the A condensate water pump; and a washing valve control assembly is arranged on the first backwashing pipeline and the second backwashing pipeline. The first and second backwashing pipelines cross the A and B branches, the condensate water pump blocked by the filter screen does not need to be powered off and disassembled for washing, backwashing can be completed by using outlet branch water flow of the standby pump, online cleaning of the condensate water pump filter screen is realized, and the reliability of the equipment is greatly improved.

Description

Technical Field

[0001] This application relates to the technical field of condensate delivery systems in thermal power plants, and in particular to an online backwashing device for the outlet filter screen of a condensate pump in a thermal power plant. Background Technology

[0002] In thermal power plants, condensate pumps are key power equipment that delivers condensate from the condenser hot well to the deaerator and low-pressure heater. Their operational reliability is directly related to the safe and stable operation of the unit.

[0003] During actual operation, residual welding slag, gasket fragments, pipeline corrosion, and impurities entering the condenser from leaks in the heating heaters after unit maintenance all flow with the condensate to the condensate pump outlet filter. These impurities accumulate after being intercepted by the filter, increasing the pressure difference across the filter. This not only increases the operating resistance of the condensate pump but, in severe cases, can also limit its flow capacity, threatening the safe operation of the unit.

[0004] Currently, the traditional method is as follows: when the outlet filter of the running A condensate pump becomes clogged, it is necessary to first manually start the standby B condensate pump, then stop and disconnect the power to the A condensate pump, and finally manually remove the filter for offline cleaning. However, this method still has many drawbacks: First, the operation is cumbersome, time-consuming and labor-intensive. The manual dismantling and cleaning process is quite time-consuming. If the pump in another branch fails during the cleaning process, the filter screen of the other branch also needs to be removed. There is no effective way to deal with the extreme situation where the filter screens of both pumps are clogged at the same time, which will directly lead to the overall shutdown of the unit and seriously affect the availability of the equipment. Second, it affects the unit's vacuum. During the dismantling process, improper operation or internal leakage of valves may affect the subsequent vacuum of the condenser, thereby reducing the unit's thermal efficiency.

[0005] Third, the degree of automation is low, relying on manual judgment and operation, which makes it impossible to achieve real-time monitoring and early warning of the filter status, and there are risks such as misoperation and missing early maintenance opportunities.

[0006] In addition, the results of manual cleaning vary from person to person, which can lead to inconsistent cleaning effects and a lack of control over the final cleaning outcome. Summary of the Invention

[0007] This application provides an online backwashing device for the outlet filter screen of a condensate pump in a thermal power plant, which solves the problems of traditional condensate pump filter screen cleaning methods in the prior art requiring shutdown and power outage, being cumbersome to operate, and easily causing safety hazards to the unit.

[0008] This application provides an online backwashing device for the outlet filter screen of a condensate pump in a thermal power plant, including a condensate pump A, a filter screen A, a condensate pump B, a filter screen B, and a condensate outlet header. The condensate pump A and the filter screen A are connected in series to form a branch A, and the condensate pump B and the filter screen B are connected in series to form a branch B. The branch A and the branch B are connected to a low-pressure heater after merging through the condensate outlet header. The device is characterized by further including a first backwashing pipeline and a second backwashing pipeline. The inlet end of the first backwash pipeline is connected to the rear branch of the B condensate pump in the B branch, and its outlet end is connected between the A filter screen and the A condensate pump in the A branch, for backwashing the A filter screen through the outlet water of the B condensate pump. The inlet end of the second backwash pipeline is connected to the rear branch of the A condensate pump in the A branch, and its outlet end is connected between the B filter screen and the B condensate pump in the B branch, for backwashing the B filter screen through the outlet water of the A condensate pump. Both the first and second backflushing pipelines are equipped with flushing valve control components.

[0009] Preferably, it also includes a differential pressure sensor and a control module; The differential pressure sensors are respectively installed on both the inlet and outlet sides of the A filter and the B filter to detect the pressure difference before and after the filter and transmit the detection signal to the control module. The control module can control the start and stop of the corresponding condensate pump and the opening and closing of the flushing valve control assembly according to the pressure difference signal.

[0010] Preferably, the flushing valve control assembly includes a backwash gate valve and a flow regulator arranged sequentially along the flushing water flow direction; The branch before the inlet of filter A and filter B is also equipped with a corresponding drain control valve, and the impurity water discharged during backwashing can be discharged from the system through the corresponding drain control valve.

[0011] Preferably, the control module is connected to the backwash gate valve control, and the control module is further preset with a first differential pressure threshold and a second differential pressure threshold, wherein the first differential pressure threshold is less than the second differential pressure threshold; When the differential pressure sensor detects that the pressure difference across the filter screen on the operating branch is greater than the first differential pressure threshold, the control module will first start the condensate pump of the other branch, then stop the condensate pump corresponding to the branch, and then open the backwash gate valve of the backwash pipeline corresponding to the branch, using the condensate pump outlet of the other branch to backwash it. The stopping action of the condensate pump on the blocked side is after the starting action of the condensate pump, which is the power pump of the backwash pipeline, that is, it follows the action sequence of starting first and then stopping. When the differential pressure sensor detects that the pressure difference across the filter screen of any operating branch is greater than or equal to the second differential pressure threshold, the control module will issue a high-level alarm signal and issue an audible and visual alarm to remind manual intervention.

[0012] Preferably, the flow regulating component is a flow regulating valve or a flow meter, and the control module is signal-connected to the flow regulating component to realize differential pressure-flow correlation regulation; When the flow regulating component is the flow regulating valve, the control module can control the flow opening of the flow regulating valve according to the pressure difference across the filter screen; When the flow regulator is the flow meter, the backwash gate valve includes at least one electrically controlled valve with an adjustable opening. The control module can control the actual opening of the electrically controlled valve according to the pressure difference across the filter screen.

[0013] Preferably, the control module allows the opening of the flushing valve control assembly and the corresponding drainage control valve of the backwash pipeline corresponding to the blocked branch only when the condensate pump of the blocked branch is in a stopped state, and the condensate pump of the other branch or the emergency backwash pump of the emergency backwash branch is in a running state.

[0014] Preferably, the control module is further provided with a timing unit and a preset duration, the preset duration including a preset stabilization duration and a preset rinsing duration; The control module can continuously monitor the real-time filter pressure difference at the differential pressure sensor during the backwashing process. When the real-time filter pressure difference drops below the first differential pressure threshold and remains stable for a time greater than or equal to the preset stable duration, the backwashing is determined to be complete and the backwashing program is exited. The timing unit is used to collect the duration of the backwashing process.

[0015] Preferably, if the duration of the backwashing process exceeds the preset washing duration, and the real-time filter pressure difference at the differential pressure sensor is still greater than the first differential pressure threshold, the control module will determine that the filter of that side branch is abnormal and issue an equipment abnormality alarm.

[0016] Preferably, it also includes an external emergency backwash branch, which is connected to an external demineralized water or condensate makeup water system, and its outlet is respectively located before the outlet of the first backwash pipeline and the second backwash pipeline. When the differential pressure sensors on both sides of filter A and filter B detect a pressure difference exceeding the first differential pressure threshold, the control module will trigger a high-risk alarm, issue an equipment maintenance alarm, and open the external emergency backwash branch to backwash filter A and filter B.

[0017] Preferably, the drain control valve is located before the inlet of the corresponding filter screen and after the branch inlet control valve of the corresponding filter screen. During backwashing, impurities are flushed from the inside to the outside with the reverse water flow and discharged into the drain or condensate recovery system through the drain control valve. The branch inlet control valve of the corresponding filter screen is closed when the backwashing procedure is performed on that side branch to prevent the backwash water containing impurities from flowing back into the condenser.

[0018] The beneficial effects of this application are as follows: The online backwashing device for the outlet filter screen of the condensate pump in this application for thermal power plants, through the first and second backwashing pipelines bridging branches A and B, eliminates the need for power outages and disassembly of the condensate pump with clogged filter screens. Backwashing can be completed using the outlet branch water flow of the running standby pump, achieving online cleaning of the condensate pump filter screen and greatly improving the reliability of the equipment. When the running condensate pump trips due to a fault, the condensate pump in hot standby can start in a very short time. In the extreme case of simultaneous filter screen clogging in both pump branches, an emergency backwashing pump can be used to introduce external demineralized water or condensate makeup water as an emergency backwashing power source to simultaneously flush the filter screens on both sides, so as to quickly restore the unit operation and, in conjunction with equipment inspection and alarm, further ensure the safe and stable operation of the unit. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the conventional layout of condensate pump pipelines in the existing technology; Figure 2 A schematic diagram illustrating the installation and application of the online backwashing device provided in this application.

[0021] Figure label: 1. Condenser; 2. A branch inlet control valve; 3. A filter screen; 4. A condensate pump; 5. A condensate pump outlet check valve; 6. A condensate pump outlet control valve; 7. Condensate outlet header; 8. B branch inlet control valve; 9. B filter screen; 10. B condensate pump; 11. B condensate pump outlet check valve; 12. B condensate pump outlet control valve; 13. Differential pressure sensor; 14. Low-pressure heater; 15. A side backflushing pipeline inlet control valve; 16. A side 17. Backwash gate valve; 18. Backwash pipeline outlet control valve on side A; 19. Flow regulator on side A; 20. Primary valve before condensate pump B; 21. Secondary valve before condensate pump B; 22. Backwash pipeline inlet control valve on side B; 23. Backwash gate valve on side B; 24. Backwash pipeline outlet control valve on side B; 25. Flow regulator on side B; 26. Primary valve before condensate pump A; 27. Secondary valve before condensate pump A; 28. Emergency backwash pump; 29. ​​Backwash pump regulating valve. Detailed Implementation

[0022] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The following is combined with Figure 1 and Figure 2 This application describes the online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant, as provided in the embodiments of this application.

[0024] like Figure 1 As shown, in the prior art, condensate pump sets typically employ a one-in-one-outstand configuration. Branch A includes, in series along the condensate transport direction, an A-branch inlet control valve 2, an A-filter 3, an A-condensate pump 4, an A-condensate pump outlet check valve 5, and an A-condensate pump outlet control valve 6. Branch B is connected in parallel with Branch A at the condensate outlet of condenser 1 as a standby branch, including, symmetrically opposite to Branch A, a B-branch inlet control valve 8, a B-filter 9, a B-condensate pump 10, a B-condensate pump outlet check valve 11, and a B-condensate pump outlet control valve 12. The outlets of both Branch A and Branch B are connected to the condensate outlet header 7, meaning the outlets of both the A-condensate pump outlet control valve 6 and the B-condensate pump outlet control valve 12 are connected to the condensate outlet header 7, used to transport the condensate condensed by condenser 1 to the low-pressure heater 14.

[0025] When filter A 3 becomes clogged during operation, the traditional method requires stopping condensate pump A 4 and manually removing filter A 3 for cleaning, which is cumbersome and poses safety risks.

[0026] To solve the above problems, such as Figure 2 As shown, this embodiment provides an online backwashing device for the outlet filter of a condensate pump in a thermal power plant, which adds a first backwashing pipeline and a second backwashing pipeline to the existing pipeline. Furthermore, in this embodiment, the A branch inlet control valve 2, the A condensate pump outlet control valve 6, the B branch inlet control valve 8, and the B condensate pump outlet control valve 12 are all electrically controlled valves.

[0027] Specifically, the inlet of the first backflushing pipeline is connected to the downstream of the check valve 11 at the outlet of the B condensate pump in branch B, and its outlet is connected between filter 3 (A) and condensate pump 4 (A) in branch A. The inlet of the second backflushing pipeline is connected to the downstream of the check valve 5 at the outlet of the A condensate pump in branch A, and its outlet is connected between filter 9 (B) and condensate pump 10 (B) in branch B. The pipe materials of the first and second backflushing pipelines are the same as those of the condensate outlet header 7, and their pipe diameters and pressure ratings match the maximum working pressure of the condensate outlet header 7.

[0028] Along the direction of the flushing water flow, the first backwash pipeline is sequentially equipped with an A-side backwash pipeline inlet control valve 15, an A-side backwash gate valve 16, an A-side backwash pipeline outlet control valve 17, and an A-side flow regulator 18. Along the direction of the flushing water flow, the second backwash pipeline is sequentially equipped with a B-side backwash pipeline inlet control valve 21, a B-side backwash gate valve 22, a B-side backwash pipeline outlet control valve 23, and a B-side flow regulator 24. Flow regulators 18 and 24 can be flow regulating valves or flow meters. When used as flow regulating valves, they can directly control the flushing force; when used as flow meters, they are linked to the flushing pressure of the corresponding condensate pump or the backwash gate valve, controlling the flow rate by adjusting the pump power or valve opening.

[0029] An A-side drain control valve is installed before the inlet of filter A 3 and after the inlet control valve 2 of branch A; a B-side drain control valve is installed before the inlet of filter B 9 and after the inlet control valve 8 of branch B. Specifically, in this embodiment, the A-side drain control valve includes a primary valve 25 and a secondary valve 26 before the A condensate pump, and the B-side drain control valve includes a primary valve 19 and a secondary valve 20 before the B condensate pump. During backwashing, impurities are flushed from the inside out with the reverse water flow and discharged into the ditch or drainage recovery system through the corresponding drain control valve.

[0030] In some specific embodiments, the device further includes differential pressure sensors 13 and a control module. The differential pressure sensors are respectively installed on both the inlet and outlet sides of filter A 3 and filter B 9, used to detect the pressure difference across the corresponding filter in real time and transmit the detection signal to the control module. In this embodiment, all differential pressure sensors 13 are signal-connected to the control module, which is a programmable logic controller (PLC). Its output terminals are respectively connected to condensate pump A 4, condensate pump B 10, each backwash gate valve, each flow regulator, each drain control valve, and the alarm device.

[0031] In some specific embodiments, the control module is preset with a first differential pressure threshold ΔP1 and a second differential pressure threshold ΔP2, where ΔP1 < ΔP2. The second differential pressure threshold ΔP2 can be selected based on the maximum pressure that the selected pipe material can withstand, and it must be less than the maximum pressure that the selected pipe material can withstand. When the differential pressure sensor detects that the differential pressure across the filter screen reaches the second differential pressure threshold ΔP2, it means that the pressure on one side of the filter screen is about to reach the critical value that the pipe can withstand. To achieve the desired flushing effect, the flushing water flow generally needs to have a pressure greater than the pressure difference across the filter screen to overcome any possible original water flow pressure and flush impurities from the other side of the filter screen. However, this also means that the instantaneous pressure of the required flushing water flow passing through this pipe may be greater than the maximum pressure that the pipe can withstand, and flushing cannot continue; manual intervention is required. The first differential pressure threshold ΔP1 can be adaptively selected based on past filter clogging conditions. To avoid frequent pump shutdowns affecting the normal delivery of condensate, the first differential pressure threshold ΔP1 can be appropriately increased to be selected based on the pressure difference of the water flow on both sides when the filter is half-clogged, and generally should not exceed half of the maximum pressure that the selected pipe material can withstand. The working logic and backwashing process of this device are as follows: When branch A is operating normally, and the differential pressure sensor of filter A 3 detects a differential pressure greater than the first differential pressure threshold ΔP1, the control module automatically shuts down condensate pump A 4 and starts condensate pump B 10. Condensate pump A 4 starts after condensate pump B 10, following a start-then-stop sequence. At this time, the control module executes anti-maloperation interlocking logic: the corresponding gate valve and drain control valve of the backwash pipeline on side A are only allowed to open if the condensate pump on the blocked side (side A) is shut down and the condensate pump on the other side (side B) is running. Simultaneously, the inlet control valve 2 of branch A is closed to prevent backwash water containing impurities from flowing back to condenser 1.

[0032] For example, in this embodiment, if ΔP1 is 0.05 MPa and ΔP2 is 0.15 MPa, when the differential pressure sensor detects a pressure difference of 0.08 MPa across filter A 3, which is greater than 0.05 MPa of ΔP1 and less than 0.15 MPa of ΔP2, the control module determines that filter A 3 is clogged. At this time, the control module will control the execution of the following backwashing procedure: The control module issues a command to start the standby B condensate pump 10, stop the A condensate pump 4, and close the A condensate pump outlet control valve 6 and the A branch inlet control valve 2. Open the primary valve 25 and the secondary valve 26 before the A condensate pump in sequence; Next, sequentially open the inlet control valve 15, the backwash gate valve 16, and the outlet control valve 17 of the backwash pipeline on side A, and control the opening of the flow regulating valve 17 or the backwash gate valve 16 on side A according to the current pressure difference. At this time, the high-pressure water from the outlet of the B condensate pump 10 flows in reverse through the first backwash pipeline into the A filter screen 3, flushing the filter screen from the inside out, washing away the impurities attached to the outside of the filter screen, and the backwash water carrying the impurities is discharged from the system through the primary valve 25 and the secondary valve 26 before the A condensate pump on side A.

[0033] In addition, to avoid damage to the pipe or filter structure caused by excessive instantaneous flow impact pressure, the control module is also equipped with a third differential pressure threshold ΔP3, where ΔP1 < ΔP3 < ΔP2. When the pressure difference across the filter is greater than ΔP3 and less than ΔP2, the larger the pressure difference, the smaller the initial opening of the flow regulating valve, allowing it to initially penetrate the blockage with a small flow rate. Subsequently, the opening of the flow regulating valve is gradually increased according to the set gradient until it is fully open, forming a high-pressure water impact that progressively flushes away the blockage.

[0034] In terms of backwash water flow regulation, the control module can achieve the following differential pressure-flow correlation regulation: If the flow regulating component is a flow regulating valve, when the pressure difference is greater than the first threshold but less than the third threshold, the larger the pressure difference, the larger the initial opening of the valve. When the pressure difference is greater than the third threshold but less than the second threshold, it indicates severe blockage. At this time, the larger the pressure difference, the smaller the initial opening of the flow regulating valve should be. First, the blockage is permeated with a small flow rate, and then the opening is gradually increased to full opening according to the set gradient to form high-pressure water impact and avoid transient impact damaging the filter screen.

[0035] If the flow regulating component is a flow meter, the control module adjusts the actual opening degree of the electric control valve in the backwash gate valve according to the feedback from the flow meter to control the flushing force.

[0036] The control module also includes a timing unit and preset durations. The preset durations include a preset stabilization time and a preset flushing time. The preset stabilization time is greater than or equal to 3 seconds and less than or equal to 30 seconds. The preset flushing time can be selected based on past cleaning data and generally does not exceed 30 minutes. During backwashing, the timing unit of the control module operates continuously. When the real-time filter pressure differential drops below the first pressure differential threshold ΔP1 and remains stable for a time greater than or equal to the preset stabilization time, flushing is considered complete. The control module closes the corresponding gate valves, flow regulating valves, and drain control valves, automatically restarts condensate pump A 4, stops condensate pump B 10, and restores the initial state.

[0037] If the backwashing duration exceeds the preset backwashing duration and the pressure difference is still greater than the first threshold, the control module determines that the filter is abnormal and issues an equipment abnormality alarm.

[0038] In some specific embodiments, the backwashing device further includes an external emergency backwashing branch, which is connected to an external demineralized water or condensate makeup water system, and its outlet is respectively located before the outlet of the first backwashing pipeline and the second backwashing pipeline. When the differential pressure sensors on both sides of filter A 3 and filter B 9 detect a pressure difference exceeding the first differential pressure threshold ΔP1, the control module will trigger a high-risk alarm, issuing an equipment maintenance alarm to remind manual inspection of whether there is a signal fault between differential pressure sensor 13 and the control module, and to activate the external emergency backwash branch. This branch connects to an external demineralized water or condensate water supply system, including an emergency backwash pump 27 and a backwash pump regulating valve 28 connected in series along the water inlet direction. Its outlets are respectively located between filter A 3 and condensate pump 4, and between filter B 9 and condensate pump 10, and are located before the outlets of the first and second backwash pipelines, thus enabling emergency backwashing in the event of simultaneous blockage of both pumps using an external water source.

[0039] As a further optimization, the control module can also be configured to execute a pulse backwash mode, which involves periodically and rapidly opening and closing the backwash gate valve to create pressure fluctuations, thereby enhancing the removal of impurities adhering to the filter screen surface. For example, a cycle of 3 seconds on and 2 seconds off can be repeated every 5 seconds. This periodic pressure fluctuation creates alternating positive and negative pressure impacts on the filter screen surface, effectively enhancing the removal of stubborn impurities, and is particularly suitable for cleaning oily or sticky impurities.

[0040] Meanwhile, the control module is connected to the unit's distributed control system (DCS) via hardwiring, uploading parameters such as filter differential pressure, backwash status, valve opening, and pump operating status to the DCS system in real time. It also supports remote control commands such as remotely starting the backwash program and modifying threshold parameters, achieving deep integration with the power plant's centralized control system.

[0041] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An online backwashing device for the outlet filter screen of a condensate pump in a thermal power plant, comprising a condensate pump A, a filter screen A, a condensate pump B, a filter screen B, and a condensate outlet header, wherein the condensate pump A and the filter screen A are connected in series to form branch A, and the condensate pump B and the filter screen B are connected in series to form branch B, wherein branch A and branch B are connected to a low-pressure heater via the condensate outlet header, characterized in that... It also includes a first backflushing line and a second backflushing line; The inlet end of the first backwash pipeline is connected to the rear branch of the B condensate pump, and its outlet end is connected between the A filter and the A condensate pump, for backwashing the A filter through the outlet water of the B condensate pump. The inlet end of the second backwash pipeline is connected to the rear branch of the A condensate pump, and its outlet end is connected between the B filter and the B condensate pump, for backwashing the B filter through the outlet water of the A condensate pump. Both the first and second backflushing pipelines are equipped with flushing valve control components.

2. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 1, characterized in that, It also includes a differential pressure sensor and a control module; The differential pressure sensors are respectively installed on both the inlet and outlet sides of the A filter and the B filter to detect the pressure difference before and after the filter and transmit the detection signal to the control module. The control module can control the start and stop of the corresponding condensate pump and the opening and closing of the flushing valve control assembly according to the pressure difference signal.

3. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 2, characterized in that, The flushing valve control assembly includes a backwash gate valve and a flow regulator arranged sequentially along the flushing water flow direction; The branch lines before the inlets of filter A and filter B are also equipped with corresponding drainage control valves.

4. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 3, characterized in that, The control module is connected to the backwash gate valve control, and the control module is also preset with a first differential pressure threshold and a second differential pressure threshold, wherein the first differential pressure threshold is less than the second differential pressure threshold. When the differential pressure sensor detects that the pressure difference across the filter screen on the operating branch is greater than the first differential pressure threshold, the control module will stop the condensate pump corresponding to the branch, open the backwash gate valve of the backwash pipeline corresponding to the branch, and start the condensate pump of another branch as a power pump to backwash it. The stopping action of the condensate pump on the blocked side occurs after the starting action of the condensate pump, which serves as the power pump for the backflushing pipeline. When the differential pressure sensor detects that the pressure difference across the filter screen of any operating branch is greater than or equal to the second differential pressure threshold, the control module will issue a high-level alarm signal.

5. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 4, characterized in that, The flow regulating component is a flow regulating valve or a flow meter, and the control module is signal-connected to the flow regulating component; When the flow regulating component is the flow regulating valve, the control module can control the flow opening of the flow regulating valve according to the pressure difference across the filter screen. When the flow regulator is the flow meter, the backwash gate valve includes at least one electrically controlled valve with an adjustable opening. The control module can control the actual opening of the electrically controlled valve according to the pressure difference across the filter screen.

6. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 5, characterized in that, The control module allows the opening of the flushing valve control assembly and the corresponding drainage control valve of the backwash pipeline corresponding to the blocked side branch only when the condensate pump of the blocked side branch is in a stopped state.

7. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 6, characterized in that, The control module is also equipped with a timing unit and a preset duration, the preset duration including a preset stable duration and a preset rinsing duration; The control module can continuously monitor the real-time filter pressure difference at the differential pressure sensor during the backwashing process. When the real-time filter pressure difference drops below the first differential pressure threshold and remains stable for a time greater than or equal to the preset stable duration, the backwashing is determined to be complete and the backwashing program is exited. The timing unit is used to collect the duration of the backwashing process.

8. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 7, characterized in that, If the backwashing process lasts longer than the preset backwashing time, and the real-time filter pressure difference at the differential pressure sensor is still greater than the first differential pressure threshold, the control module will determine that the filter of that side branch is abnormal and issue an equipment abnormality alarm.

9. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 2, characterized in that, It also includes an external emergency backwash branch, which is connected to an external demineralized water or condensate water supply system, and its outlet is respectively located before the outlet of the first backwash pipeline and the second backwash pipeline. When the differential pressure sensors on both sides of filter A and filter B detect a pressure difference exceeding the first differential pressure threshold, the control module will trigger a high-risk alarm, issue an equipment maintenance alarm, and open the external emergency backwash branch to backwash filter A and filter B.

10. The online backwashing device for the outlet filter screen of the condensate pump in a thermal power plant according to claim 3, characterized in that, The drainage control valve is located before the inlet of the corresponding filter screen and after the branch inlet control valve of the corresponding filter screen. During backwashing, impurities are flushed from the inside to the outside with the reverse water flow and discharged into the ditch or drainage recovery system through the drainage control valve.

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