Method for controlling outlet valve of low-pressure heater drain pump, system, and storage medium

Abstract

The present invention relates to a method for controlling an outlet valve of a low-pressure heater drain pump, a system, and a storage medium. The method comprises the following steps: step S1, sending an opening degree-increasing instruction to an outlet valve of a low-pressure heater drain pump; step S2, in response to completing the execution of the opening degree-increasing instruction, acquiring a liquid level height inside a low-pressure heater, if the current liquid level height is lower than the liquid level height acquired last time, executing step S3, and if the current liquid level height is higher than the liquid level height acquired last time, executing step S4; and step S3, sending an operating frequency-reducing instruction to the low-pressure heater drain pump, in response to completing the execution of the operating frequency-reducing instruction, acquiring a liquid level height inside the low-pressure heater, and if the current liquid level height reaches a preset value, executing step S1, otherwise, executing step S3. Compared with the prior art, the present invention has the advantages of reducing throttling loss, and improving economic and environmental benefits, etc.

Description

Low-pressure heater drain pump outlet control method, system, storage medium TECHNICAL FIELD

[0001] The present application relates to the technical field of feedwater regenerative technology, in particular to a low-pressure heater drain pump outlet control method, system, storage medium. BACKGROUND

[0002] The feedwater regenerative system is the core of the thermal system of the power plant, and its operation and regulation play a crucial role in the thermal economy of the unit, and is an important part of the thermal cycle. It uses the extraction steam of the high and low pressure cylinders of the steam turbine to heat the feedwater, thereby reducing the exhaust loss and increasing the feedwater temperature entering the boiler, improving the thermal cycle efficiency of the power plant. The steam that has heated the feedwater will form drain, which will accumulate in the heater. The drain has a certain temperature, and direct discharge into the condenser will cause a certain heat loss. Therefore, the low-pressure heating drain pump is usually used to discharge to the low-pressure heater condensate side outlet to recover the drain heat.

[0003] In actual operation, it is found that the low-pressure heating drain pump operates at a frequency close to the working frequency at high load, and the drain adjustment door opening degree is only less than 50%, which has a large throttling loss, and the frequency converter output increases, and the coil overheats seriously.

[0004] In summary, there is currently a lack of a low-pressure heater drain pump outlet control method to solve or solve the aforementioned problems. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a low-pressure heater drain pump outlet control method, system, storage medium to solve or partially solve the problem of large throttling loss in the feedwater regenerative system of the power plant.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] In one aspect of the present application, a low-pressure heater drain pump outlet control method is provided, comprising the following steps:

[0008] Step S1, sending an opening degree increasing instruction to the low-pressure heater drain pump outlet control valve;

[0009] Step S2, in response to the completion of the opening degree increasing instruction, acquiring the liquid level height in the low-pressure heater, if the current liquid level height is lower than the last acquired liquid level height, executing step S3, if the current liquid level height is higher than the last acquired liquid level height, executing step S4;

[0010] Step S3, send a working frequency reduction instruction to the low-pressure heater drainage pump, and obtain the liquid level height in the low-pressure heater after the working frequency reduction instruction is executed; if the current liquid level height reaches a preset value, execute step S1, otherwise execute step S3;

[0011] Step S4, send a valve opening reduction instruction to the low-pressure heater drainage pump outlet valve.

[0012] As a preferred technical solution, the generator set is applied to a medium load and / or a high load.

[0013] As a preferred technical solution, the control method further comprises the following steps:

[0014] Step S5, in response to reaching a preset stable condition, save the current low-pressure heater drainage pump outlet valve opening value, and complete the valve opening experiment under the current load condition.

[0015] As a preferred technical solution, the stable condition is that the fluctuation degree of the heater drainage pump outlet valve opening and / or the fluctuation degree of the liquid level height in the low-pressure heater is less than a preset threshold.

[0016] As a preferred technical solution, in step S2, further comprising:

[0017] If the current liquid level height is equal to the last obtained liquid level height, execute step S1.

[0018] Another aspect of the present application provides a power plant feedwater regenerative system, comprising a condenser and at least one low-pressure heater module connected with the condenser, wherein the low-pressure heating module comprises:

[0019] a low-pressure heater;

[0020] a variable frequency drainage pump connected with the low-pressure heater;

[0021] a drainage adjusting valve connected with the variable frequency drainage pump, wherein the drainage adjusting valve and the variable frequency drainage pump are used to realize the low-pressure heater drainage pump outlet valve control method.

[0022] As a preferred technical solution, the low-pressure heating module further comprises:

[0023] an emergency drainage valve connected with the low-pressure heater and the condenser, respectively.

[0024] As a preferred technical solution, the condenser is connected with the low-pressure heater module through a condensate pump and a desuperheater.

[0025] In another aspect of the present application, an electronic device is provided, comprising one or more processors and a memory having stored therein one or more programs, the one or more programs including instructions for performing the foregoing low-pressure heater drain pump outlet damper control method.

[0026] In another aspect of the present application, a computer-readable storage medium is provided, comprising one or more programs for execution by one or more processors of an electronic device, the one or more programs including instructions for performing the foregoing low-pressure heater drain pump outlet damper control method.

[0027] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0028] (1) Reducing throttling loss: In view of the problem that the drain pump frequency and the drain adjustment door opening degree cannot be well matched, resulting in large throttling loss, the present application provides a control method for the low-pressure heater drain pump outlet damper, which realizes full opening of the drain pump outlet damper as much as possible to reduce throttling loss under the condition of unit operation and without installing a measuring point.

[0029] (2) Improving economic and environmental benefits: By controlling the low-pressure heater drain pump outlet damper, the drain pump operating frequency is reduced in the form of increasing the damper opening degree under the premise of ensuring the stability of the water level in the low-pressure heater, thereby effectively reducing the power consumption of the water pump, reducing carbon emissions, and having good economic benefits.

[0030] (3) Wide application prospect: By realizing the damper opening degree experiment under load conditions and recording the opening degree size under different load conditions, a mapping between the conditions and the damper opening degree can be further established, and the damper opening degree is directly determined according to the mapping during control, further reducing energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is a schematic diagram of a power plant feedwater regenerative system in the embodiment,

[0032] wherein 1 is a condenser, 2 is a low-pressure heater, 3 is a variable frequency drain pump, 4 is a drain adjustment door, 5 is an emergency drain door, 6 is a condensate pump, 7 is a drain cooler, 8 is a pressure measuring point, 9 is a condensate pump inlet door, and 10 is a condensate pump outlet door. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0034] In the description of the utility model, it needs to explain that, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship commonly placed when the utility model product is used, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0035] Embodiment 1

[0036] This embodiment recovers the drain heat in the power plant feedwater regenerative system by gradually draining and finally discharging to the outlet of a certain low-pressure heater (assumed to be No. 8 low-pressure heater) through a low-pressure heater drain pump, aiming at the drain of the low-pressure heater. The low-pressure heater drain pump (i.e. frequency conversion drain pump 3) operates in a frequency conversion mode to control the water level of No. 8 low-pressure heater through spontaneous frequency change, and to automatically control the drain pressure through the drain adjusting door, so as to ensure that the drain pressure is always greater than the condensate pressure, enabling the drain to be recovered to the condensate.

[0037] During the operation of the unit, for safety considerations, a pressure measuring point cannot be installed at the outlet of No. 8 low-pressure heater, but only at the inlet of the desuperheater (i.e. pressure measuring point 8 in Fig. 1), while the pressure measuring point is located at 0 m in the steam turbine room. Thereafter, the condensate sequentially passes through the desuperheater and the low-pressure heater, the inner elbow in the heater has multiple processes and is long, and No. 8 low-pressure heater is located at 6 m or even higher in the steam turbine room. Therefore, the condensate pressure at the outlet of No. 8 low-pressure heater is necessarily lower than the inlet pressure of the desuperheater. Thus, it is unreasonable to set the drain pressure set value to be higher than the inlet pressure of the desuperheater. In order to maintain the high pressure, the outlet adjusting door of the drain pump is closed, causing throttling loss. Meanwhile, in order to maintain the water level of No. 8 low-pressure heater, the output of the frequency converter is increased, and the coil is seriously heated.

[0038] In view of the foregoing problems, the embodiment provides a low-pressure heater drain pump outlet adjusting door control method, which is applied to the drain adjusting door 4 and the frequency conversion drain pump 3 in the power plant feedwater regenerative system. By means of a safe experimental method, the drain adjusting door is fully opened, throttling loss is reduced, and the coil heating of the drain pump is reduced.

[0039] Referring to Fig. 1, the power plant feedwater regenerative system includes a condenser 1 and a plurality of low-pressure heater modules (corresponding to No. 8 low-pressure heater, No. 9 low-pressure heater and No. 10 low-pressure heater in Fig. 1) connected with the condenser 1. The condenser 1 is connected with the low-pressure heater modules through a condensate pump 6 and a desuperheater 7. The low-pressure heating module includes a low-pressure heater 2, a frequency conversion drain pump 3 and a drain adjusting door 4 connected in sequence, and further includes an emergency drain door 5 connected with the low-pressure heater 2 and the condenser 1, respectively.

[0040] The system works as follows: the condensate in the condenser 1 passes through the condensate pump inlet door 9, the condensate pump 6, the condensate pump outlet door 10, the desuperheater 7 into the multi-stage low-pressure heater module. In each module, the condensate enters the low-pressure heater 2 through the water inlet door, and the heated desuperheated water enters the next-stage low-pressure heater module through the variable-frequency desuperheated water pump 3 and the desuperheated water regulating door 4, so as to further reduce the heat loss through multi-stage energy recovery. When an emergency occurs, the condensate in the low-pressure heater 2 is discharged into the condenser 1 through the emergency desuperheated water door 5.

[0041] The low-pressure heater desuperheated water pump outlet regulating door control method comprises the following steps:

[0042] Step S0: confirming that each heater emergency desuperheated water door can normally act, and that the heater water level protection is put into operation, so as to ensure that the protection reliably acts in the case of abnormal conditions, the turbine does not enter water, and the condensate is not interrupted.

[0043] Step S1: controlling the low-pressure heater desuperheated water pump outlet regulating door to increase the opening degree.

[0044] Step S2: collecting the liquid level height in the low-pressure heater through a sensor. If the current liquid level height is lower than the liquid level height obtained last time, step S3 is executed; if the current liquid level height is higher than the liquid level height obtained last time, step S4 is executed; and if the current liquid level height is equal to the liquid level height obtained last time, step S1 is executed.

[0045] Step S3: reducing the working frequency of the low-pressure heater desuperheated water pump, and collecting the liquid level height in the low-pressure heater again. If the current liquid level height reaches a preset value, step S1 is executed; otherwise, step S3 is executed.

[0046] Step S4: sending a command to reduce the opening degree of the low-pressure heater desuperheated water pump outlet regulating door.

[0047] It should be noted that the desuperheated water pressure and flow cannot be increased by increasing the frequency of the desuperheated water pump. On the one hand, it is not energy-saving, and more importantly, it can cause the desuperheated water flow to be greater than the steam extraction amount, and finally the 8 water level to drop, and the desuperheated water pump to trip.

[0048] Step S5: when the fluctuation degree of the opening degree of the heater desuperheated water pump outlet regulating door and / or the fluctuation degree of the liquid level height in the low-pressure heater is less than a preset threshold, the current opening degree value of the low-pressure heater desuperheated water pump outlet regulating door is saved, and the regulating door opening degree experiment under the current load condition is completed.

[0049] It should be noted that, considering the large amount of steam extraction, high inlet pressure, and large amount of drainage, the drainage pump is not prone to cavitation, and the 8th water level control is relatively stable. The experiment is carried out from high load to medium load, that is, after the full opening of the adjustment door is successful at high load, the original state is restored, the unit load is reduced, and the adjustment door is fully opened again to ensure the accuracy of the experimental results and the safety of the experiment.

[0050] Considering that the pipeline resistance loss is small when the adjustment door is fully opened at low load, the pump operating point is in the large flow and low head region, the steam extraction amount is small, the drainage amount is small, and the pump cannot work stably, the self-generation control mode is adopted at low load to avoid the influence of the fluctuation of the 8th water level on the safe operation of the unit.

[0051] In summary, the method reduces the pressure by slowly opening the drainage adjustment door. If the 8th water level decreases, the frequency is automatically reduced to raise the 8th water level to the normal value, and then the adjustment door is opened again until it is fully opened. If the 8th water level rises when the adjustment door is opened, it indicates that the drainage pressure is lower than the outlet pressure of the 8th low-level condensate side, and the drainage cannot be discharged. At this time, the drainage adjustment door is closed to maintain the drainage pressure. This method can achieve full opening of the drainage pump outlet adjustment door to reduce throttling loss without installing measuring points, reduce the current of the drainage pump and reduce the heating of the coil. At the same time, the lowest load threshold corresponding to the full opening of the adjustment door can be found by this method. When the load is lower than the threshold, the original control mode is adopted, and when the load is higher than the threshold, the adjustment door is automatically fully opened.

[0052] Taking a 650 MW once-through reheat unit in a power plant as an example, after adopting this method, at high load of the unit, the drainage adjustment door is fully opened, the 8th water level is maintained stable, and the frequency of the drainage pump is reduced by 3-5 Hz and the current is reduced by 26-72 A before and after the test at the same load, which has obvious energy-saving effect. After modifying the control logic on April 14, 2024 (the adjustment door is automatically fully opened at high load (450 MW-650 MW)), it has been nearly a month, the low-level drainage pump runs stably, and there is no fluctuation of the 8th water level and flow. The frequency and current of the drainage pump at high load have decreased obviously compared with before the modification. According to the average current reduction of 47 A, the plant power consumption can be saved by 24.75 KWh per hour at high load. At the same time, the temporary cooling fan of the drainage pump motor has been removed, and there is no high temperature alarm of the drainage pump coil, which indirectly reduces the energy consumption.

[0053] Example 2

[0054] The embodiment provides an electronic device, including one or more processors and a memory, the memory has one or more programs stored therein, and the one or more programs include instructions for executing the low-pressure heater drainage pump outlet adjustment door control method as described in embodiment 1.

[0055] Example 3

[0056] This embodiment provides a computer-readable storage medium comprising one or more programs for execution by one or more processors of an electronic device, the one or more programs comprising instructions for performing the low-pressure heater drain pump outlet damper control method as described in Example 1.

[0057] The above description is merely that of a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be encompassed within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for controlling the outlet regulating valve of a low-pressure heater condensate pump, characterized in that, Includes the following steps: Step S1: Send an instruction to increase the opening degree to the regulating valve at the outlet of the low-pressure heater drain pump; Step S2: In response to the completion of the increased opening command, obtain the liquid level height in the low-pressure heater. If the current liquid level height is lower than the previously obtained liquid level height, proceed to step S3. If the current liquid level height is higher than the previously obtained liquid level height, proceed to step S4. Step S3: Send a command to reduce the operating frequency to the low-pressure heater drain pump. In response to the completion of the command to reduce the operating frequency, obtain the liquid level height in the low-pressure heater. If the current liquid level height reaches the preset value, execute step S1; otherwise, execute step S3. Step S4: Send a command to reduce the opening degree of the regulating valve at the outlet of the low-pressure heater drain pump.

2. The method for controlling the outlet regulating valve of a low-pressure heater condensate pump according to claim 1, characterized in that, Generator sets used in medium and / or high load conditions.

3. The method for controlling the outlet regulating valve of a low-pressure heater condensate pump according to claim 1, characterized in that, The control method further includes the following steps: Step S5: In response to reaching the preset stable condition, save the current low-pressure heater drain pump outlet valve opening value and complete the valve opening test under the current load condition.

4. The method for controlling the outlet regulating valve of a low-pressure heater condensate pump according to claim 3, characterized in that, The stability condition is that the fluctuation of the heater drain pump outlet valve opening and / or the fluctuation of the liquid level height in the low-pressure heater are less than a preset threshold.

5. The method for controlling the outlet regulating valve of a low-pressure heater condensate pump according to claim 1, characterized in that, Step S2 further includes: If the current liquid level is equal to the previously obtained liquid level, then proceed to step S1.

6. A power plant feedwater regeneration system, characterized in that, The system includes a condenser (1) and at least one low-pressure heater module connected to the condenser (1), the low-pressure heater module comprising: Low-pressure heater (2); A variable frequency condensate pump (3) is connected to the low-pressure heater (2); A drain regulating valve (4) is connected to the variable frequency drain pump (3). The drain regulating valve (4) and the variable frequency drain pump (3) are used to implement the low-pressure heater drain pump outlet regulating valve control method as described in any one of claims 1-5.

7. A power plant feedwater regeneration system according to claim 6, characterized in that, The low-pressure heating module also includes: Emergency drain valve (5) is connected to the low-pressure heater (2) and the condenser (1), respectively.

8. A power plant feedwater regeneration system according to claim 6, characterized in that, The condenser (1) is connected to the low-pressure heater module via a condensate pump (6) and a cooler (7).

9. An electronic device, characterized in that, include: One or more processors and a memory, wherein the memory stores one or more programs, the one or more programs including instructions for executing the low-pressure heater drain pump outlet regulating valve control method as described in any one of claims 1-5.

10. A computer-readable storage medium, characterized in that, It includes one or more programs that are executed by one or more processors of an electronic device, the one or more programs including instructions for performing the low-pressure heater drain pump outlet regulating valve control method as described in any one of claims 1-5.

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