阅读说明：本技术 一种低温省煤器及疏水回收耦合供水系统和方法 (Low-temperature economizer and drainage recovery coupling water supply system and method ) 是由 陈筑 王海彬 王建 李杨 林森 韩旭 武伟 姜彦辰 卢刚 孙龙威 石辰峰 徐仁 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种低温省煤器及疏水回收耦合供水系统,包括：主凝结水供水单元,用于将凝结水依次经一号低加、二号低加、三号低加和四号低加加热后输入除氧器；低温省煤器回水单元,包括第一回水支路、第二回水支路和第三回水支路,用于将低温省煤器回水经所述第一回水支路、或所述第二回水支路、或所述第三回水支路输入所述主凝结水供水单元；疏水回收单元,包括第一回收支路、第二回收支路和第三回收支路,用于将热网疏水经所述第一回收支路、或所述第二回收支路、或所述第三回收支路回收至所述主凝结水供水单元,从而可以根据不同回水温度将低省回水及热网疏水回收至机组凝结水管路不同位置,提高了机组的安全性和经济性。(The invention discloses a low-temperature economizer and a drainage recovery coupling water supply system, which comprises: the main condensed water supply unit is used for sequentially heating condensed water through a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater and then inputting the heated condensed water into a deaerator; the low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch and is used for inputting the return water of the low-temperature economizer into the main condensation water supply unit through the first return water branch, the second return water branch or the third return water branch; the drain recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch, and is used for recovering drain of a heat supply network to the main condensation water supply unit through the first recovery branch, the second recovery branch or the third recovery branch, so that low-saving return water and the drain of the heat supply network can be recovered to different positions of a condensation water pipeline of the unit according to different return water temperatures, and the safety and the economy of the unit are improved.)

1. The utility model provides a low temperature economizer and hydrophobic recovery coupling water supply system which characterized in that includes:

the main condensed water supply unit is used for sequentially heating condensed water through a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater and then inputting the heated condensed water into a deaerator;

the low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch and is used for inputting the return water of the low-temperature economizer into the main condensation water supply unit through the first return water branch, the second return water branch or the third return water branch;

the drainage recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch and is used for recovering drainage of a heat supply network to the main condensation water supply unit through the first recovery branch, the second recovery branch or the third recovery branch;

the outlet of the first water return branch and the outlet of the first recovery branch are respectively connected with the outlet of the fourth low-pressure water side, the outlet of the second water return branch is connected with the outlet of the third low-pressure water side, the outlet of the third water return branch and the outlet of the second recovery branch are respectively connected with the inlet of the third low-pressure water side, and the outlet of the third recovery branch is connected with the inlet of the second low-pressure water side.

2. The system of claim 1, wherein the first water return branch, the second water return branch and the third water return branch are respectively provided with an electric stop door, and an inlet of the first water return branch, an inlet of the second water return branch and an inlet of the third water return branch are connected to a main pipeline of the low-temperature economizer water return unit in common.

3. The system of claim 2, wherein an electric stop door, an electric adjusting door and a manual door are sequentially arranged on a main pipeline of the low-temperature economizer water return unit according to the water flow direction.

4. The system of claim 1, wherein an inlet of the first recovery branch, an inlet of the second recovery branch and an inlet of the third recovery branch are connected to a main pipeline of the drainage recovery unit, and an electric check valve, a check valve and a manual valve are sequentially arranged on the first recovery branch, the second recovery branch and the third recovery branch according to a water flow direction.

5. The system of claim 4, wherein a thermocouple is disposed on the main conduit of the hydrophobic recovery unit.

6. The system of claim 1, wherein said main condensate supply unit further comprises a first low add side inlet power gate, a first low add and second low add power bypass power gate, a second low add side outlet power gate, a third low add side inlet power gate, a third low add side outlet power gate, a fourth low add side inlet power gate, a fourth low add side outlet power gate, wherein,

the export of first return water branch road with the export of first recovery branch road is connected respectively No. four low side of adding water export electrically operated gate with between the entry of oxygen-eliminating device, the exit linkage of second return water branch road is in No. three low side of adding water export electrically operated gate with between No. four low side of adding water entry electrically operated gate, the export of third return water branch road with the export of second recovery branch road is connected respectively No. two low side of adding water export electrically operated gate with between No. three low side of adding water entry electrically operated gate, the exit linkage of third recovery branch road No. one low add with No. two low water side pipelines between adding.

7. A low-temperature economizer and hydrophobic recovery coupling water supply method is applied to the low-temperature economizer and hydrophobic recovery coupling water supply system according to any one of claims 1 to 6, and the method comprises the following steps:

if the return water temperature of the low-temperature economizer is not lower than the outlet temperature of the water side with the fourth low addition and the third low addition and the fourth low addition are not disconnected, the return water of the low-temperature economizer is input into the main condensation water supply unit based on the first return water branch, and the second return water branch and the third return water branch are closed;

if the return water temperature is lower than the outlet temperature of the water side with the low addition number four and not lower than the outlet temperature of the water side with the low addition number three and the water side with the low addition number four are not disconnected, inputting the return water of the low-temperature economizer into the main condensation water supply unit based on the second return water branch, and closing the first return water branch and the third return water branch;

if the return water temperature is lower than the outlet temperature of the water side with the third low water addition and the fourth low water addition are not disconnected, the return water of the low-temperature economizer is input into the main condensation water supply unit based on the third return water branch, and the first return water branch and the second return water branch are closed.

8. The method of claim 7, wherein the method further comprises:

and if the third low plus and the fourth low plus are disconnected, forcibly opening the second water return branch.

9. The method of claim 7, wherein the method further comprises:

if the temperature of the drain of the heat supply network is lower than a preset threshold value and the second low-plus is not split, inputting the drain of the heat supply network into the main condensed water supply unit based on the third recovery branch, and closing the first recovery branch and the second recovery branch;

and if the temperature of the drainage of the heat supply network is not lower than the preset threshold value and the second low-plus is not split, inputting the drainage of the heat supply network into the main condensed water supply unit based on the second recovery branch, and closing the first recovery branch and the third recovery branch.

10. The method of claim 9, wherein the method further comprises:

and if the second low-plus-split mode is adopted, the heat supply network is input into the main condensation water supply unit based on the second recovery branch, and the first recovery branch and the third recovery branch are closed.

Technical Field

The application relates to the technical field of power plants, in particular to a low-temperature economizer and drainage recovery coupling water supply system and method.

Background

The design temperature of the drainage of the heat supply network is generally 40-90 ℃, in order to improve the unit economy of power plants, the drainage of the heat supply network is recovered to an inlet of a deaerator in some power plants, a low-temperature economizer is additionally arranged, the design return water temperature of the low-temperature economizer is 102 ℃, and the return water of the low-temperature economizer is returned to a second low-temperature water outlet.

Along with the enhancement of the operation flexibility of the unit and the increase of the heat supply steam extraction amount, the low water-saving return water temperature is higher during low-load operation, so that the condition of no steam extraction during low-pressure operation is caused, meanwhile, the condition that the drainage temperature of a heat supply network is lower than the temperature of condensate water at an outlet of a low-pressure heater is caused, and the safety and the economical efficiency of the unit are reduced.

Therefore, how to reduce the temperature difference between the return water of the low-temperature economizer or the drain water of the heat supply network and the condensed water so as to improve the safety and the economical efficiency of the unit is a technical problem to be solved at present.

Disclosure of Invention

The invention discloses a low-temperature economizer and a drainage recovery coupling water supply system, which are used for solving the technical problem that the temperature difference between return water of the low-temperature economizer or drainage of a heat supply network and condensed water is large in the prior art, and comprise the following components:

the main condensed water supply unit is used for sequentially heating condensed water through a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater and then inputting the heated condensed water into a deaerator;

the low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch and is used for inputting the return water of the low-temperature economizer into the main condensation water supply unit through the first return water branch, the second return water branch or the third return water branch;

the drainage recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch and is used for recovering drainage of a heat supply network to the main condensation water supply unit through the first recovery branch, the second recovery branch or the third recovery branch;

preferably, the first water return branch, the second water return branch and the third water return branch are respectively provided with an electric stop door, and an inlet of the first water return branch, an inlet of the second water return branch and an inlet of the third water return branch are connected to a main pipeline of the low-temperature economizer water return unit.

Preferably, an electric stop door, an electric adjusting door and a manual door are sequentially arranged on a main pipeline of the low-temperature economizer water return unit in the water flow direction.

Preferably, the inlet of the first recovery branch, the inlet of the second recovery branch and the inlet of the third recovery branch are connected to the main pipeline of the drainage recovery unit, and the first recovery branch, the second recovery branch and the third recovery branch are sequentially provided with an electric stop valve, a check valve and a manual valve according to the water flow direction.

Preferably, a thermocouple is arranged on the main pipeline of the hydrophobic recovery unit.

Preferably, the main condensed water supply unit further comprises a first low water-adding side inlet electric door, a first low water-adding and second low water-adding side electric bypass door, a second low water-adding side outlet electric door, a third low water-adding side inlet electric door, a third low water-adding side outlet electric door, a fourth low water-adding side inlet electric door, and a fourth low water-adding side outlet electric door, wherein,

the export of first return water branch road with the export of first recovery branch road is connected respectively No. four low side of adding water export electrically operated gate with between the entry of oxygen-eliminating device, the exit linkage of second return water branch road is in No. three low side of adding water export electrically operated gate with between No. four low side of adding water entry electrically operated gate, the export of third return water branch road with the export of second recovery branch road is connected respectively No. two low side of adding water export electrically operated gate with between No. three low side of adding water entry electrically operated gate, the exit linkage of third recovery branch road No. one low add with No. two low water side pipelines between adding.

Correspondingly, the application also provides a low-temperature economizer and a drainage recovery coupling water supply method, which are applied to the low-temperature economizer and the drainage recovery coupling water supply system, and the method comprises the following steps:

if the return water temperature of the low-temperature economizer is not lower than the outlet temperature of the water side with the fourth low addition and the third low addition and the fourth low addition are not disconnected, the return water of the low-temperature economizer is input into the main condensation water supply unit based on the first return water branch, and the second return water branch and the third return water branch are closed;

if the return water temperature is lower than the outlet temperature of the water side with the low addition number four and not lower than the outlet temperature of the water side with the low addition number three and the water side with the low addition number four are not disconnected, inputting the return water of the low-temperature economizer into the main condensation water supply unit based on the second return water branch, and closing the first return water branch and the third return water branch;

if the return water temperature is lower than the outlet temperature of the water side with the third low water addition and the fourth low water addition are not disconnected, the return water of the low-temperature economizer is input into the main condensation water supply unit based on the third return water branch, and the first return water branch and the second return water branch are closed.

Preferably, the method further comprises: and if the third low plus and the fourth low plus are disconnected, forcibly opening the second water return branch.

Preferably, the method further comprises: and if the temperature of the heat supply network drainage is lower than a preset threshold value and the second low-plus is not split, inputting the heat supply network drainage into the main condensed water supply unit based on the third recovery branch, and closing the first recovery branch and the second recovery branch.

Preferably, the method further comprises: and if the second low-plus-split mode is adopted, the heat supply network is input into the main condensation water supply unit based on the second recovery branch, and the first recovery branch and the third recovery branch are closed.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a low-temperature economizer and drainage recovery coupling water supply system and method, wherein the system comprises: the main condensed water supply unit is used for sequentially heating condensed water through a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater and then inputting the heated condensed water into a deaerator; the low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch and is used for inputting the return water of the low-temperature economizer into the main condensation water supply unit through the first return water branch, the second return water branch or the third return water branch; the drainage recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch and is used for recovering drainage of a heat supply network to the main condensation water supply unit through the first recovery branch, the second recovery branch or the third recovery branch; therefore, the low-saving return water and the drain water of the heat supply network can be recovered to different positions of the condensed water pipeline of the unit according to different return water temperatures, the temperature difference between the low-saving return water and the drain water of the heat supply network and the condensed water of the afflux pipeline is reduced, the steam extraction of the unit is increased, and the safety and the economical efficiency of the unit are improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram illustrating a low-temperature economizer and a water drainage recovery coupling water supply system according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart illustrating a low-temperature economizer and a water drainage recovery coupling water supply method according to an embodiment of the invention;

in FIG. 1, number one is low plus; 2. adding the second lower part; 3. adding the third lower part; 4. adding low No. four; 5. a first low water adding side inlet electric door; 6. a second low water adding side outlet electric door; 7. a third low water adding side inlet electric door; 8. a third low water adding side outlet electric door; 9. a fourth low water adding side inlet electric door; 10. a fourth low water adding side outlet electric door; 11. the water side electric bypass door with the first low pressure addition and the second low pressure addition; 12. a first electrically operated shutoff gate; 13. a second electrically operated shutoff gate; 14. a third electrically operated shutoff gate; 15. a fourth electric stop gate; 16. an electrically operated adjustment gate; 17. a fourth manual door; 18. a fifth electric stop gate; 19. a first check valve; 20. a first manual door; 21. a sixth electrically operated shutoff gate; 22. a second non-return valve; 23. a second manual door; 24. a seventh electrically operated shutoff gate; 25. a third non-return valve; 26. a third manual door; 27. and a thermocouple.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the embodiment, the low-temperature economizer utilizes the condensed water in the low-pressure regenerative heating system, and the discharged water is introduced into the deaerator, so that the exhaust gas temperature of the boiler is reduced, and the circulating heat efficiency of a power plant is improved.

The embodiment of the application provides a low temperature economizer and hydrophobic coupling water supply system that retrieves, includes:

the main condensed water supply unit is used for sequentially heating condensed water through a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater and then inputting the heated condensed water into a deaerator;

the low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch and is used for inputting the return water of the low-temperature economizer into the main condensation water supply unit through the first return water branch, the second return water branch or the third return water branch;

the drainage recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch and is used for recovering drainage of a heat supply network to the main condensation water supply unit through the first recovery branch, the second recovery branch or the third recovery branch;

the outlet of the first water return branch and the outlet of the first recovery branch are respectively connected with the outlet of the fourth low-pressure water side, the outlet of the second water return branch is connected with the outlet of the third low-pressure water side, the outlet of the third water return branch and the outlet of the second recovery branch are respectively connected with the inlet of the third low-pressure water side, and the outlet of the third recovery branch is connected with the inlet of the second low-pressure water side.

Specifically, the drainage recovery coupling water supply system of the low-temperature economizer comprises a main condensation water supply unit, a low-temperature economizer backwater unit and a drainage recovery unit. The main condensation water supply unit comprises a first low water supply unit, a second low water supply unit, a third low water supply unit and a fourth low water supply unit, and is used for sequentially heating condensed water and inputting the heated condensed water to the deaerator, so that the working efficiency of the deaerator is improved.

The low-temperature economizer return water unit comprises a first return water branch, a second return water branch and a third return water branch, and can selectively pass through the three branches according to corresponding temperatures.

The hydrophobic recovery unit comprises a first recovery branch, a second recovery branch and a third recovery branch, and can selectively pass through the three branches according to the temperature condition in the pipeline.

In order to further improve the operational reliability of the unit, in some embodiments, the first water return branch, the second water return branch and the third water return branch are respectively provided with an electric stop door, and an inlet of the first water return branch, an inlet of the second water return branch and an inlet of the third water return branch are connected to a main pipeline of the low-temperature economizer water return unit.

Specifically, as shown in fig. 1, a first electric stop gate 12 is arranged on the first water return branch, a second electric stop gate 13 is arranged on the second water return branch, a third electric stop gate 14 is arranged on the third water return branch, and inlets of the three water return branches are connected to a main pipeline of a low-temperature economizer water return unit together and used for controlling the on-off of the low-temperature economizer water return.

In order to further improve the running reliability of the unit, in some embodiments, an electric stop door, an electric adjusting door and a manual door are sequentially arranged on a main pipeline of the low-temperature economizer water return unit in the water flow direction.

Specifically, as shown in fig. 1, a fourth electric stop gate 15, an electric adjusting gate 16 and a fourth manual gate 17 are respectively arranged on the main pipe of the water return unit of the low-temperature economizer according to the direction of water flow, the fourth electric stop gate 15 and the fourth manual gate 17 are used for controlling the on-off of the water flow of the main pipe of the water return unit of the low-temperature economizer, and the electric adjusting gate 16 is used for controlling the flow rate of the water flow.

In order to further improve the operational reliability of the unit, in some embodiments, an inlet of the first recovery branch, an inlet of the second recovery branch, and an inlet of the third recovery branch are connected to a main pipeline of the drainage recovery unit, and an electric stop valve, a check valve, and a manual valve are sequentially disposed on the first recovery branch, the second recovery branch, and the third recovery branch according to a water flow direction.

Specifically, as shown in fig. 1, the heat supply network drainage recovery device is provided with 3 branches, an inlet of a first recovery branch is connected to a main pipeline of a drainage recovery unit, and a fifth electric stop gate 18, a first check gate 19 and a first manual gate 20 are respectively arranged according to a water flow direction; the inlet of the second recovery branch is connected with the main pipeline of the drainage recovery unit, and a sixth electric stop valve 21, a second check valve 22 and a second manual valve 23 are respectively arranged according to the water flow direction; the inlet of the third recovery branch is connected to the main pipeline of the drainage recovery unit, and a seventh electric stop valve 24, a third check valve 25 and a third manual valve 26 are respectively arranged according to the water flow direction. The check valve is used for preventing water flow from flowing backwards, and the electric check valve and the manual valve are used for controlling the on-off of the water flow.

In order to accurately determine the hydrophobic temperature of the heat supply network, in some embodiments, a thermocouple 27 is provided on the main conduit of the hydrophobic recovery unit, as shown in fig. 1.

In order to further improve the operational reliability of the unit, in some embodiments, as shown in fig. 1, the main condensate water supply unit further includes a first low watering side inlet power gate 5, a first low watering side and second low watering side power bypass gate 11, a second low watering side outlet power gate 6, a third low watering side inlet power gate 7, a third low watering side outlet power gate 8, a fourth low watering side inlet power gate 9, and a fourth low watering side outlet power gate 10, wherein,

the export of first return water branch road with the export of first recovery branch road is connected respectively No. four low side of adding water export electrically operated gate 10 with between the entry of oxygen-eliminating device, the exit linkage of second return water branch road is in No. three low side of adding water export electrically operated gate 8 with No. four low side of adding water entry electrically operated gate 9 between, the export of third return water branch road with the export of second recovery branch road is connected respectively No. two low side of adding water export electrically operated gate 6 with No. three low side of adding water entry electrically operated gate 7 between, the exit linkage of third recovery branch road No. one low add 1 with No. two low water side pipelines that add between 2.

The application also provides a low-temperature economizer and a hydrophobic recovery coupling water supply method, which are applied to the low-temperature economizer and the hydrophobic recovery coupling water supply system, and as shown in fig. 2, the method comprises the following steps:

step S101, if the return water temperature of the low-temperature economizer is not lower than the outlet temperature of the water side with the fourth low addition and the third low addition and the fourth low addition are not split, inputting the return water of the low-temperature economizer into the main condensation water supply unit based on the first return water branch, and closing the second return water branch and the third return water branch;

specifically, when the return water temperature is not lower than the water outlet temperature of 4 from the fourth low, and the water outlet temperature of 3 from the third low and the water outlet temperature of 4 from the fourth low are not disconnected, the return water of the low-temperature economizer directly flows into the deaerator through the first return water branch, and at this time, the first electric stop gate 12 needs to be opened, and the second electric stop gate 13 and the third electric stop gate 14 need to be closed, so that an operation mode that only the first return water branch can pass through water flow is formed.

Step S102, if the return water temperature is lower than the outlet temperature of the water side with the low addition number four and is not lower than the outlet temperature of the water side with the low addition number three and the outlet temperature of the water side with the low addition number four are not disconnected, inputting the return water of the low-temperature economizer into the main condensation water supply unit based on the second return water branch, and closing the first return water branch and the third return water branch;

specifically, when the recovery temperature of the low-temperature economizer is lower than the water outlet temperature of the fourth low plus 4 and is not lower than the water inlet temperature of the third low plus 3, and the third low plus 3 and the fourth low plus 4 are not subjected to splitting operation, the return water of the low-temperature economizer flows into the fourth low plus 4 through the second return water branch for heating treatment, and at the moment, the second electric stop door 13 needs to be opened, and the first electric stop door 12 and the third electric stop door 14 need to be closed, so that an operation mode that only the second return water branch can pass through water flow is formed.

Step S103, if the return water temperature is lower than the outlet temperature of the water side with the third low water addition and the fourth low water addition are not disconnected, the return water of the low-temperature economizer is input into the main condensation water supply unit based on the third return water branch, and the first return water branch and the second return water branch are closed.

Specifically, when the recovery temperature of the low-temperature economizer is lower than the water outlet temperature of the third low water plus 3, and the third low water plus 3 and the fourth low water plus 4 are not subjected to splitting operation, the return water of the low-temperature economizer flows into the third low water plus 3 through the third return water branch for heating treatment, and at the moment, the third electric stop door 14 needs to be opened, and the first electric stop door 12 and the second electric stop door 13 need to be closed, so that an operation mode that only the third return water branch can pass through water flow is formed.

To further improve the unit operational reliability, in some embodiments, the method further comprises: and if the third low plus and the fourth low plus are disconnected, forcibly opening the second water return branch.

Specifically, when the splitting operation is required, the water flow passes through other branches directly without passing through a low-load device. When the third low plus 3 and the fourth low plus 4 are disconnected, the operation mode of low-saving return water switching needs to be quitted, and the second electric stop gate 13 of the second return water branch is forcibly opened to ensure the normal operation of the system.

To further improve the unit operational reliability, in some embodiments, the method further comprises:

and if the temperature of the heat supply network drainage is lower than a preset threshold value and the second low-plus is not split, inputting the heat supply network drainage into the main condensed water supply unit based on the third recovery branch, and closing the first recovery branch and the second recovery branch.

And if the temperature of the drainage of the heat supply network is not lower than the preset threshold value and the second low-plus is not split, inputting the drainage of the heat supply network into the main condensed water supply unit based on the second recovery branch, and closing the first recovery branch and the third recovery branch.

Specifically, when the temperature of the drainage of the heat supply network is lower than a preset threshold value and no splitting operation is performed on the second low-plus 2, the water flow needs to be guided into the second low-plus 2 of the main condensed water supply unit from the third recovery branch for heating treatment, at this time, the seventh electric stop gate 24 is opened, and the fifth electric stop gate 18 and the sixth electric stop gate 21 are closed, so that an operation mode that only the third recovery branch can pass through the water flow is formed.

When the temperature of the drainage of the heat supply network is not lower than a preset threshold value and no splitting operation is carried out on the second low-plus-2, the water flow needs to be guided into the third low-plus-3 of the main condensed water supply unit from the second recovery branch for heating treatment, at the moment, the sixth electric stop gate 21 is opened, and the fifth electric stop gate 18 and the seventh electric stop gate 24 are closed, so that the running mode that only the second recovery branch can pass through the water flow is formed.

When the second recovery branch and the third recovery branch have a fault problem, the first recovery branch is used for performing drainage recovery, and at the moment, the fifth electric stop gate 18 is opened, and the sixth electric stop gate 21 and the seventh electric stop gate 24 are closed, so that an operation mode that only the first recovery branch can pass through water flow is formed.

To further improve the unit operational reliability, in some embodiments, the method further comprises: and if the second low-plus-split mode is adopted, the heat supply network is input into the main condensation water supply unit based on the second recovery branch, and the first recovery branch and the third recovery branch are closed.

Specifically, when the splitting operation is performed by adding 2 to the second lowest level, the water flow enters the main condensed water supply unit without being heated by adding 2 to the second lowest level, and at this time, the sixth electric stop gate 21 needs to be opened, and the fifth electric stop gate 18 and the seventh electric stop gate 24 need to be closed, so that an operation mode that only the second recovery branch can pass through the water flow is formed.

The sequence of steps S101, S102, and S103 may be interchanged.

Through applying the technical scheme, a certain power plant has the following technical effects:

safety:

1. the arrangement of the backwater and heat supply network drainage recovery pipeline of the low-temperature economizer can reduce the temperature difference between the backwater and the condensed water of the afflux pipeline, avoid the strong vibration of the pipeline during the low-temperature economizer and heat supply input period, and ensure the safety of the unit.

2. The arrangement of the heat supply network drainage recovery pipeline improves the temperature of condensed water at the inlet of the deaerator, improves the deaerator deoxidizing effect, and reduces the dissolved oxygen of water supply.

The economic efficiency is as follows:

1. the low-temperature economizer unit branch increases the third low-pressure steam extraction amount, and improves the unit energy consumption ratio by 0.01%.

2. The arrangement of the heat supply drainage recovery unit pipeline improves the side flow of the third low water feeding and the fourth low water feeding, increases the air suction amount and further improves the unit operation efficiency by 0.04 percent.

The early investment of the system is about 30 thousands, the cost can be recovered when a single unit operates in one heating season according to the calculation of a standard coal purchasing unit price of 760 yuan and the single unit generates 14 hundred million kw.h of single unit power in 2020, and the system has good economy.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not necessarily depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.