Inverted pump control system applied to boiler water supply

Abstract

The utility model relates to a reverse pump control system applied to boiler water supply. The reverse pump control system comprises a DCS, a main water feeding pump M3, a standby pump M2, a first frequency converter ATV2 and a second frequency converter ATV3, an input terminal of the main water feeding pump M3 is connected with an output terminal of the second frequency converter ATV3, an input terminal of the standby pump M2 is connected with an output terminal of the first frequency converter ATV2, the first frequency converter ATV2 and the second frequency converter ATV3 are connected with a power source, and the power source is connected with the DCS. The reverse pump control system applied to boiler water supply further comprises a first relay KA1, a second relay KA2, a third relay KA3, a first change-over switch SA2 and a second change-over switch SA3. By arranging the first change-over switch SA2 and the second change-over switch SA3, operation of the standby pump M2 and the main water feeding pump M3 can be manually controlled, the purpose of pump reversing is achieved, and therefore the problem that when the main water feeding pump M3 breaks down and needs to be reversed, a control circuit needs to be frequently disassembled and connected, and consequently a DCS card terminal is damaged is solved.

Description

Technical Field

[0001] This application relates to the field of feedwater pump technology, and more particularly to a reverse pump control system for boiler feedwater. Background Technology

[0002] Feed pumps are used to supply water to boilers. Common drive methods include steam-driven (steam turbine driven) and electric (electric motor driven). In large units, feed pumps are generally steam-driven. For example, in thermal power plants, steam-driven methods can effectively reduce coal consumption and plant power consumption, and improve power generation efficiency compared to electric methods.

[0003] Pump rotation is used to avoid overloading a single pump by using multiple pumps to handle the workload, requiring different pumps to work in rotation. In process industrial production, to ensure the service life of pumps, standby pumps are kept in a qualified standby state, and the alternating operation of operating and standby pumps is a routine part of the work.

[0004] In the non-ferrous metal smelting industry, waste heat boilers are used to recover waste heat from flue gas. Water circulation is a key component ensuring the boiler's normal operation, with the boiler feedwater pump continuously supplying circulating water. When the main feedwater pump malfunctions, manual intervention at the DCS control station is required to switch the feedwater pump's control circuitry and achieve pump rerouting. However, this method necessitates frequent disconnection and reconnection of the control circuitry, which can easily damage the wiring terminals of the DCS card. Utility Model Content

[0005] To solve or partially solve the problems existing in the related technologies, this application provides a reverse pump control system for boiler feedwater.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] A pump reversing control system for boiler feedwater includes a DCS, a main feedwater pump M3, a standby pump M2, a first frequency converter ATV2, and a second frequency converter ATV3. The input terminal of the main feedwater pump M3 is connected to the output terminal of the second frequency converter ATV3. The input terminal of the standby pump M2 is connected to the output terminal of the first frequency converter ATV2. The first frequency converter ATV2 and the second frequency converter ATV3 are respectively connected to a power supply. The pump reversing control system for boiler feedwater also includes a first relay KA1, a second relay KA2, and a third relay KA3.

[0008] The normally open contact of the first relay KA1 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the main second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form an operation switching circuit.

[0009] The normally open contact of the second relay KA2 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a standby switching circuit.

[0010] The normally open contact of the third relay KA3 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a start / stop switching circuit.

[0011] The prepared switching circuit is equipped with a first changeover switch SA2, and the start / stop switching circuit is equipped with a second changeover switch SA3.

[0012] Optionally, contact 1 of the first changeover switch SA2 is electrically connected to the control power supply of the standby pump M2, and contact 2 is electrically connected to the neutral wire;

[0013] The first changeover switch SA2 has its contact 3 electrically connected to the control power supply of the standby pump M2, and its contact 5 electrically connected to the first frequency converter ATV2. The first changeover switch SA2 has its contacts 4 and 6 electrically connected to the normally open contacts of the third relay KA3 and the second relay KA2, respectively, to form the first automatic control circuit.

[0014] Optionally, contact 1 of the second changeover switch SA3 is electrically connected to the control power supply of the main water pump M3, and contact 2 is electrically connected to the neutral wire;

[0015] The second changeover switch SA3 has its contact 3 electrically connected to the control power supply of the main water pump M3, and its contact 5 electrically connected to the second frequency converter ATV3. The contacts 4 and 6 of the second changeover switch SA3 are electrically connected to the normally closed contacts of the third relay KA3 and the second relay KA2, respectively, to form the second automatic control circuit.

[0016] Optionally, a contactor KM2, a stop button SB3, and a start button SB4 are provided between the contact 2 of the first changeover switch SA2 and the neutral wire. The start button SB4 is connected in series with the stop button SB3, and the start button SB4 is connected in parallel with the normally open contact of the contactor KM2 to form a first manual control circuit.

[0017] A contactor KM3, a stop button SB5, and a start button SB6 are provided between the contact 2 of the second changeover switch SA3 and the neutral line. The start button SB6 is connected in series with the stop button SB5, and the start button SB6 is connected in parallel with the normally open contact of the contactor KM3 to form a second manual control circuit.

[0018] Optionally, the first manual control circuit is provided with a stop indicator light HR3 and a run indicator light HR4. The stop indicator light HR3 is connected in series with the normally closed contact of the contactor KM2, and the run indicator light HR4 is connected in series with the normally open contact of the contactor KM2.

[0019] The second manual control circuit is equipped with a stop indicator light HR5 and a run indicator light HR6. The stop indicator light HR5 is connected in series with the normally closed contact of contactor KM3, and the run indicator light HR6 is connected in series with the normally open contact of contactor KM3.

[0020] Optionally, one end of the coil of the contactor KM2, the stop indicator light HR3, and the run indicator light HR4 is connected to the neutral wire;

[0021] The coil of contactor KM3, one end of the stop indicator HR5 and the run indicator HR6 are connected to the neutral wire.

[0022] Optionally, the reverse pump control system applied to boiler feedwater also includes a third changeover switch SA4;

[0023] One end of the third changeover switch SA4 is connected to the power supply, and the other end is connected in parallel to one end of the coils of the first relay KA1, the second relay KA2, and the third relay KA3. The other end of the coil is connected to the neutral wire.

[0024] Optionally, the first frequency converter ATV2 and the second frequency converter ATV3 are connected to the power supply through the first circuit breaker QF2 and the second circuit breaker QF3, respectively.

[0025] The beneficial effects of this application are as follows: This application sets up a first relay KA1, which is electrically connected to the DCS to form an operation switching circuit; sets up a second relay KA2, which is electrically connected to the DCS to form a standby switching circuit; and sets up a third relay KA3, which is electrically connected to the DCS to form a start / stop switching circuit. The operation of the standby pump M2 and the main feed water pump M3 are controlled through these three circuits.

[0026] This application enables the operation of the standby pump M2 and the main feed water pump M3 to be manually controlled by setting a first changeover switch SA2 and a second changeover switch SA3, thereby achieving the purpose of pump switching. This avoids the problem of damage to the DCS card wiring terminals caused by frequent disconnection and reconnection of the control circuit when the main feed water pump M3 fails and pump switching is required.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0028] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0029] Figure 1 This is a control block diagram of the reverse pump control system shown in the embodiments of this application;

[0030] Figure 2 This is a control circuit diagram of the reverse pump control system shown in an embodiment of this application.

[0031] Figure label: Detailed Implementation

[0032] In the description of this invention, 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," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] 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 invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly 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 them; 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 explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention as the specific circumstances dictate.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] In this invention, 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 the invention. 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.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0038] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0039] To make the objectives, technical solutions, and beneficial effects of this application clearer, the preferred embodiments of this application will be described in detail below with reference to the accompanying drawings, so as to facilitate understanding by those skilled in the art.

[0040] Example:

[0041] See Figure 1 and Figure 2A reverse pump control system for boiler feedwater includes a DCS, a main feedwater pump M3, a standby pump M2, a first frequency converter ATV2, and a second frequency converter ATV3. The input terminal of the main feedwater pump M3 is connected to the output terminal of the second frequency converter ATV3, and the input terminal of the standby pump M2 is connected to the output terminal of the first frequency converter ATV2. The first frequency converter ATV2 and the second frequency converter ATV3 are respectively connected to a power supply. The reverse pump control system for boiler feedwater also includes a first relay KA1, a second relay KA2, and a third relay KA3.

[0042] The normally open contact of the first relay KA1 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the main second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form an operation switching circuit.

[0043] The normally open contact of the second relay KA2 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a standby switching circuit.

[0044] The normally open contact of the third relay KA3 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a start / stop switching circuit.

[0045] The prepared switching circuit is equipped with a first changeover switch SA2, and the start / stop switching circuit is equipped with a second changeover switch SA3.

[0046] Further and optionally, contact 1 of the first changeover switch SA2 is electrically connected to the control power supply of the standby pump M2, and contact 2 is electrically connected to the neutral wire.

[0047] The first changeover switch SA2 has its contact 3 electrically connected to the control power supply of the standby pump M2, and its contact 5 electrically connected to the first frequency converter ATV2. The first changeover switch SA2 has its contacts 4 and 6 electrically connected to the normally open contacts of the third relay KA3 and the second relay KA2, respectively, to form the first automatic control circuit.

[0048] Further and optionally, contact 1 of the second changeover switch SA3 is electrically connected to the control power supply of the main water pump M3, and contact 2 is electrically connected to the neutral wire;

[0049] The second changeover switch SA3 has its contact 3 electrically connected to the control power supply of the main water pump M3, and its contact 5 electrically connected to the second frequency converter ATV3. The contacts 4 and 6 of the second changeover switch SA3 are electrically connected to the normally closed contacts of the third relay KA3 and the second relay KA2, respectively, to form the second automatic control circuit.

[0050] Further and optionally, a contactor KM2, a stop button SB3, and a start button SB4 are provided between the contact 2 of the first changeover switch SA2 and the neutral wire. The start button SB4 is connected in series with the stop button SB3, and the start button SB4 is connected in parallel with the normally open contact of the contactor KM2 to form a first manual control circuit.

[0051] A contactor KM3, a stop button SB5, and a start button SB6 are provided between the contact 2 of the second changeover switch SA3 and the neutral line. The start button SB6 is connected in series with the stop button SB5, and the start button SB6 is connected in parallel with the normally open contact of the contactor KM3 to form a second manual control circuit.

[0052] Further and optionally, the first manual control circuit is provided with a stop indicator light HR3 and a run indicator light HR4, the stop indicator light HR3 is connected in series with the normally closed contact of contactor KM2, and the run indicator light HR4 is connected in series with the normally open contact of contactor KM2.

[0053] Further and optionally, the second manual control circuit is provided with a stop indicator light HR5 and a run indicator light HR6. The stop indicator light HR5 is connected in series with the normally closed contact of the contactor KM3, and the run indicator light HR6 is connected in series with the normally open contact of the contactor KM3.

[0054] Further and optionally, one end of the coil of the contactor KM2, the stop indicator light HR3, and the run indicator light HR4 are connected to the neutral wire;

[0055] The coil of contactor KM3, one end of the stop indicator HR5 and the run indicator HR6 are connected to the neutral wire.

[0056] Further and optionally, the reverse pump control system applied to boiler feedwater also includes a third changeover switch SA4;

[0057] One end of the third changeover switch SA4 is connected to the power supply, and the other end is connected in parallel to one end of the coils of the first relay KA1, the second relay KA2, and the third relay KA3. The other end of the coil is connected to the neutral wire.

[0058] Further and optionally, the first frequency converter ATV2 and the second frequency converter ATV3 are respectively connected to the power supply through the first circuit breaker QF2 and the second circuit breaker QF3.

[0059] Specifically, the current signal setpoint range for the first frequency converter ATV2 and the second frequency converter ATV3 is 4-20mA. Turning the first changeover switch SA2 counterclockwise connects nodes 1 and 2, activating the first manual control circuit. Pressing the field start button SB4 engages contactor KM2, closing its contacts and starting the first frequency converter ATV2. When the pressure transmitter at the water supply pipeline outlet detects low water pressure, it sends a signal back to the first frequency converter ATV2, causing it to control the standby pump M2 to run rapidly. When it detects high water pressure, it sends a signal back to the first frequency converter ATV2, causing it to control the standby pump M2 to run rapidly. M2 operates at a slow speed to achieve constant pressure regulation of water supply. Then, pressing the stop button SB3 disconnects contactor KM2, stopping the first frequency converter ATV2. Turning the first changeover switch SA2 clockwise connects nodes 3 and 4 or nodes 5 and 6, activating the first automatic control circuit. Switching is performed via the first relay KA1, the second relay KA2, and the third relay KA3, and the DCS is ready (the conditions for this are that the site is in automatic mode, the first frequency converter ATV2 is powered on and has the conditions to start, and there are no faults). The frequency converter is controlled remotely via the DCS start / stop signal, and the operating signal of the first frequency converter ATV2 is fed back to the DCS.

[0060] Turn the second changeover switch SA3 counterclockwise to connect nodes 1 and 2, thus activating the second manual control circuit. Press the field start button SB6. Contactor KM3 engages, its contacts close, and the second frequency converter ATV3 starts running. When the pressure transmitter at the water supply pipeline outlet detects low water pressure, it sends a signal to the second frequency converter ATV3, causing it to control the main water supply pump M3 to run rapidly. When it detects high water pressure, it sends a signal to the second frequency converter ATV3, causing it to control the main water supply pump M3 to run slowly, thereby achieving constant pressure regulation of the water supply. Then press... Stop button SB5, contactor KM3 is disconnected, and the second frequency converter ATV3 stops running; turn the second changeover switch SA3 clockwise to connect nodes 3 and 4 or nodes 5 and 6, and the second automatic control circuit is connected. Switching is performed through the first relay KA1, the second relay KA2 and the third relay KA3, and the DCS is ready (the judgment condition is that the site is in automatic state, the second frequency converter ATV3 is powered on and has the conditions to start and is fault-free). The second frequency converter ATV3 is controlled to run remotely through the DCS start / stop signal, and the running signal of the second frequency converter ATV3 is fed back to the DCS.

[0061] In manual control mode, pressing the start button SB4 will cause the normally open contact of contactor KM2 to close and the running indicator light HR4 to light up, indicating that the standby pump M2 has started running. Pressing the stop button SB3 will cause the normally closed contact of contactor KM2 to close and the stop indicator light HR3 to light up, indicating that the standby pump M2 has stopped running.

[0062] In manual control mode, pressing the start button SB6 will cause the normally open contact of contactor KM3 to close and the running indicator light HR6 to illuminate, indicating that the main feedwater pump M3 has started running. Pressing the stop button SB5 will cause the normally closed contact of contactor KM3 to close and the stop indicator light HR5 to illuminate, indicating that the main feedwater pump M3 has stopped running.

[0063] The third changeover switch SA4 is the selection switch between the standby pump M2 and the main feed water pump M3 on the power distribution cabinet in the power distribution room. When the standby pump M2 is selected, the third changeover switch SA4 is switched to standby pump M2, nodes 1 and 2 are connected, the first relay KA1, the second relay KA2, and the third relay KA3 are energized, and their normally open contacts close, connecting the standby pump M2 signal to the DCS channel. When the main feed water pump M3 is selected, the third changeover switch SA4 is switched to main feed water pump M3, nodes 3 and 4 are connected, nodes 1 and 2 are disconnected, the first relay KA1, the second relay KA2, and the third relay KA3 are de-energized, and their normally closed contacts close naturally, connecting the main feed water pump M3 signal to the DCS channel. The third changeover switch SA4 is not connected to the control power supply of the main feed water pump M3, but to the control power supply of the standby pump M2. Its other terminal is empty. This setting ensures that if the main feed water pump M3 suddenly loses power and stops supplying water during normal production (the pump cannot be stopped during normal production), it will automatically switch to the standby pump M2 for water supply.

[0064] The first circuit breaker QF2 is used to control the connection and disconnection of the power supply and the first frequency converter ATV2, and the second circuit breaker QF3 is used to control the connection and disconnection of the power supply and the second frequency converter ATV3.

[0065] In summary, this application establishes an operation switching circuit by setting a first relay KA1 and electrically connecting it to the DCS, a standby switching circuit by setting a second relay KA2 and electrically connecting it to the DCS, and a start / stop switching circuit by setting a third relay KA3 and electrically connecting it to the DCS. These three circuits are used to control the operation of the standby pump M2 and the main feed water pump M3.

[0066] This application sets up a first changeover switch SA2 and a second changeover switch SA3, which enables manual control of the operation of the standby pump M2 and the main feed water pump M3, thereby achieving the purpose of pump switching. This avoids the problem of damage to the DCS card wiring terminals caused by frequent disconnection and reconnection of the control circuit when the main feed water pump M3 fails and pump switching is required.

[0067] This application is equipped with a third transfer switch SA4. The third transfer switch SA4 is not connected to the control power supply of the main water supply pump M3, but is connected to the control power supply of the standby pump M2. Its other terminal is an empty terminal. This configuration ensures that if the main water supply pump M3 suddenly loses power and stops supplying water during normal operation, it will automatically switch to the standby pump M2 to supply water.

[0068] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of this application; the dimensions of the drawings are not related to the specific physical object, and the physical object dimensions can be arbitrarily changed.

Claims

1. A pump switching control system for boiler feedwater, comprising a DCS, a main feedwater pump M3, a standby pump M2, a first frequency converter ATV2, and a second frequency converter ATV3, wherein the input terminals of the main feedwater pump M3 are connected to the output terminals of the second frequency converter ATV3, the input terminals of the standby pump M2 are connected to the output terminals of the first frequency converter ATV2, and the first frequency converter ATV2 and the second frequency converter ATV3 are respectively connected to a power supply, characterized in that... The aforementioned reverse pump control system for boiler feedwater also includes: a first relay KA1, a second relay KA2, and a third relay KA3; The normally open contact of the first relay KA1 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the main second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form an operation switching circuit. The normally open contact of the second relay KA2 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a standby switching circuit. The normally open contact of the third relay KA3 is electrically connected to the first frequency converter ATV2, and the normally closed contact is electrically connected to the second frequency converter ATV3. The normally open contact and the normally closed contact are connected in parallel to the DCS to form a start / stop switching circuit. The prepared switching circuit is equipped with a first changeover switch SA2, and the start / stop switching circuit is equipped with a second changeover switch SA3.

2. The reverse pump control system for boiler feedwater as described in claim 1, characterized in that, The first changeover switch SA2 has its contact 1 electrically connected to the control power supply of the standby pump M2, and its contact 2 electrically connected to the neutral wire. The first changeover switch SA2 has its contact 3 electrically connected to the control power supply of the standby pump M2, and its contact 5 electrically connected to the first frequency converter ATV2. The first changeover switch SA2 has its contacts 4 and 6 electrically connected to the normally open contacts of the third relay KA3 and the second relay KA2, respectively, to form the first automatic control circuit.

3. The reverse pump control system for boiler feedwater as described in claim 1, characterized in that, The second changeover switch SA3 has contact 1 electrically connected to the control power supply of the main water pump M3, and contact 2 electrically connected to the neutral wire; The second changeover switch SA3 has its contact 3 electrically connected to the control power supply of the main water pump M3, and its contact 5 electrically connected to the second frequency converter ATV3. The contacts 4 and 6 of the second changeover switch SA3 are electrically connected to the normally closed contacts of the third relay KA3 and the second relay KA2, respectively, to form the second automatic control circuit.

4. The reverse pump control system for boiler feedwater as described in claim 2 or 3, characterized in that, A contactor KM2, a stop button SB3, and a start button SB4 are provided between the contact 2 of the first changeover switch SA2 and the neutral wire. The start button SB4 is connected in series with the stop button SB3, and the start button SB4 is connected in parallel with the normally open contact of the contactor KM2 to form a first manual control circuit. A contactor KM3, a stop button SB5, and a start button SB6 are provided between the contact 2 of the second changeover switch SA3 and the neutral line. The start button SB6 is connected in series with the stop button SB5, and the start button SB6 is connected in parallel with the normally open contact of the contactor KM3 to form a second manual control circuit.

5. The reverse pump control system for boiler feedwater as described in claim 4, characterized in that, The first manual control circuit is also equipped with a stop indicator light HR3 and a run indicator light HR4. The stop indicator light HR3 is connected in series with the normally closed contact of the contactor KM2, and the run indicator light HR4 is connected in series with the normally open contact of the contactor KM2. The second manual control circuit is also equipped with a stop indicator light HR5 and a run indicator light HR6. The stop indicator light HR5 is connected in series with the normally closed contact of the contactor KM3, and the run indicator light HR6 is connected in series with the normally open contact of the contactor KM3.

6. The reverse pump control system for boiler feedwater as described in claim 5, characterized in that, The coil of contactor KM2, the stop indicator HR3, and the run indicator HR4 are all connected to the neutral wire. The coil of contactor KM3, one end of the stop indicator HR5 and the run indicator HR6 are connected to the neutral wire.

7. The reverse pump control system for boiler feedwater as described in claim 1, characterized in that, The reverse pump control system applied to boiler feedwater also includes a third changeover switch SA4; One end of the third changeover switch SA4 is connected to the control power supply of the standby pump M2, and the other end is connected in parallel to one end of the coils of the first relay KA1, the second relay KA2 and the third relay KA3. The other end of the coil is connected to the neutral wire.

8. The reverse pump control system for boiler feedwater as described in claim 1, characterized in that, The first frequency converter ATV2 and the second frequency converter ATV3 are respectively connected to the power supply through the first circuit breaker QF2 and the second circuit breaker QF3.

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