An automatic spraying control system and method of a reliable bypass flue gas evaporator in a deep peak shaving background of a thermal power unit

Abstract

The application discloses a reliable bypass flue gas evaporator automatic spraying control system and method under deep peak regulation of a thermal power generating unit, which comprises an inlet flue, a bypass flue gas evaporator, an outlet flue, a waste water inlet pipeline, a boiler load signal input end, a water inlet flow electric regulating valve control module, a water inlet flow electric regulating valve feedback control module, a water inlet flow electric regulating valve, a control system switcher, a PID A controller and a PID B controller; the inlet flue is communicated with an inlet of the bypass flue gas evaporator, an outlet of the bypass flue gas evaporator is communicated with the outlet flue, a flue gas flow meter is arranged on the inlet flue, an outlet flue gas temperature meter is arranged on the outlet flue, and the outlet of the waste water inlet pipeline is communicated with a waste water inlet of the bypass flue gas evaporator in sequence through the water inlet flow electric regulating valve; the system and the method can realize automatic control of spraying of the bypass flue gas evaporator under deep peak regulation of the thermal power generating unit, and keep stable operation of the system.

Description

Technical Field

[0001] This invention belongs to the field of end-of-pipe wastewater zero discharge technology, and relates to a reliable automatic spray control system and method for bypass flue gas evaporators under the background of deep peak shaving of thermal power units. Background Technology

[0002] More and more thermal power plants are choosing to put desulfurization wastewater bypass flue gas evaporation towers into operation to achieve zero-discharge treatment of high-salinity wastewater at the end of the process. During the non-heating season or for coal-fired units supplying steam to external users, boiler loads not only fluctuate significantly in a short period during peak shaving, but also remain in a low-load, stable combustion state for much of the time. Currently, some bypass flue gas drying spray control systems rely solely on reading the flue gas temperature at the outlet of the bypass flue gas evaporation system for automatic regulation. While this method can play a regulatory role under high boiler loads, it suffers from drawbacks such as feedback parameter lag and mismatch between water volume and flue gas flow rate under low loads or with significant load fluctuations. This affects the accuracy and reliability of the automatic control system and can easily lead to evaporator caking, ash conveying pump blockages, and pipeline blockages, resulting in the system failing to operate normally under low load conditions or with frequent load fluctuations. In summary, existing bypass flue gas evaporation automatic spray control systems are no longer suitable for the operating environment under the deep peak shaving conditions of thermal power units. There is an urgent need to develop a reliable bypass flue gas evaporator automatic spray control system and method for thermal power units under deep peak shaving conditions. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a reliable automatic spray control system and method for bypass flue gas evaporators under the background of deep peak shaving of thermal power units. This system and method can realize automatic control of the spray of bypass flue gas evaporators under the deep peak shaving conditions of thermal power units and maintain stable system operation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The reliable automatic spray control system for bypass flue gas evaporators under deep peak shaving conditions in thermal power units as described in this invention includes an inlet flue, a bypass flue gas evaporator, an outlet flue, a wastewater inlet pipeline, a boiler load signal input terminal, an electric inlet water flow regulating valve control module, an electric inlet water flow regulating valve feedback control module, an electric inlet water flow regulating valve, a control system switcher, and a PID controller. A Controller and PID B Controller;

[0006] The inlet flue is connected to the inlet of the bypass flue gas evaporator, and the outlet of the bypass flue gas evaporator is connected to the outlet flue. A flue gas flow meter is installed on the inlet flue, and an outlet flue gas thermometer is installed on the outlet flue. The outlet of the wastewater inlet pipe is connected to the wastewater inlet of the bypass flue gas evaporator via an electric regulating valve for inlet flow.

[0007] The output of the flue gas flow meter is connected to the input of the inlet flow electric regulating valve control module; the output of the inlet flow electric regulating valve control module is connected to the control terminal of the inlet flow electric regulating valve; the output of the outlet flue gas thermometer is connected to the input of the inlet flow electric regulating valve feedback control module; the boiler load signal input is connected to the input of the control system switcher; the first output of the control system switcher is connected to the input of the PIDA controller; the output of the PIDA controller is connected to the input of the inlet flow electric regulating valve feedback control module; and the second output of the control system switcher is connected to the PIDA controller. A Connected to the input terminal of the controller, PID B The output of the controller is connected to the input of the feedback control module for the electric regulating valve of the inlet flow.

[0008] The further improvement of the reliable bypass flue gas evaporator automatic spray control system for thermal power units under deep peak shaving background described in this invention is as follows:

[0009] Furthermore, the output of the flue gas flow meter is connected to the input of the inlet water flow electric regulating valve control module via the flue gas flow signal transmission system.

[0010] Furthermore, the output of the outlet flue gas thermometer is connected to the input of the inlet water flow electric regulating valve feedback control module via the outlet temperature signal transmission system.

[0011] Furthermore, the outlet of the wastewater inlet pipe is connected to the wastewater inlet of the bypass flue gas evaporator via an electric regulating valve for inlet flow and an electromagnetic flow meter.

[0012] The reliable automatic spray control method for bypass flue gas evaporators in thermal power units under deep peak shaving conditions, as described in this invention, includes the following steps:

[0013] The inlet flow electric regulating valve control module adjusts the opening degree L1 of the inlet flow electric regulating valve according to the flue gas flow signal in the inlet flue measured by the flue gas flow meter;

[0014] The inlet flow electric regulating valve feedback control module calculates the deviation between the measured flue gas temperature in the outlet flue and the set value Test based on the flue gas temperature measured by the outlet flue gas thermometer, and then uses PID control based on the difference. A controller or PID B The proportional band value output by the controller is used for PID calculation to obtain the compensation opening L2 of the electric regulating valve for the inlet water flow.

[0015] Set the opening threshold ΔL for the electric regulating valve of the inlet flow rate. When L2 < ΔL, adjust the opening of the electric regulating valve of the inlet flow rate to L1; when L2 ≥ ΔL, adjust the opening of the electric regulating valve of the inlet flow rate to L = L1 + L2.

[0016] The further improvement of the reliable bypass flue gas evaporator automatic spray control method for thermal power units under deep peak shaving background described in this invention is as follows:

[0017] Furthermore, it also includes:

[0018] When the boiler load exceeds 35%, the unit is considered to be in peak-shaving mode, and the unit load fluctuates frequently. The control system switcher then switches to PID control. A Controller, PID A The proportional band value δ output by the controller A Feedback control module for electric regulating valve of inlet water flow; when boiler load ≤ 35%, it is considered that the unit is in a low-load stable combustion state, the system is relatively stable, and the control system switcher switches to PID. B Controller, PID B The proportional band value δ output by the controller B Feedback control module for electric regulating valve of inlet water flow, wherein the proportional band value δ A Less than the value of the scale band δ B .

[0019] Furthermore, the value range of L1 is 0% to 100%.

[0020] Furthermore, the ratio of the spray flow rate W1 to the inlet flue gas flow rate F1 is no greater than 1:15000.

[0021] Furthermore, the output of the flue gas flow meter is connected to the input of the inlet water flow electric regulating valve control module via the flue gas flow signal transmission system.

[0022] Furthermore, the output of the outlet flue gas thermometer is connected to the input of the inlet water flow electric regulating valve feedback control module via the outlet temperature signal transmission system.

[0023] The present invention has the following beneficial effects:

[0024] The reliable automatic spray control system and method for bypass flue gas evaporators under deep peak shaving conditions in thermal power units, as described in this invention, involves the following steps: In operation, the electric regulating valve control module for the inlet water flow sets the inlet water flow rate based on the current flue gas flow rate at the evaporator inlet. Then, the feedback control module for the electric regulating valve for the inlet water flow adjusts the opening of the electric regulating valve based on the temperature feedback of the flue gas in the evaporator outlet flue, performing feedback compensation adjustment to correct the inlet water flow rate. This achieves automatic control of the spray from the bypass flue gas evaporator, ensuring that the spray volume of the bypass flue gas evaporator remains within a reasonable range. It should be noted that this invention uses two sets of PID controllers, which automatically switch according to the boiler load via a control system switcher, ensuring a smooth transition. This enables automatic adjustment of the bypass flue gas evaporation system under deep peak shaving conditions in thermal power units, improving system stability and solving the problem of the bypass flue gas evaporation system failing to operate when the unit load fluctuates frequently. Attached Figure Description

[0025] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a structural diagram of the present invention.

[0027] Among them, 1 is the inlet flue, 2 is the bypass flue gas evaporator, 3 is the outlet flue, 4 is the wastewater inlet pipe, 5 is the boiler load signal input terminal, 6 is the inlet water flow electric regulating valve control module, 7 is the inlet water flow electric regulating valve feedback control module, 8 is the flue gas flow meter, 9 is the outlet flue gas thermometer, 10 is the electromagnetic flow meter, 11 is the inlet water flow electric regulating valve, 12 is the flue gas flow signal transmission system, 13 is the outlet temperature signal transmission system, 14 is the control system switcher, and 15 is the PID controller. A Controller, 16-bit PID B Controller. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0030] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0031] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0032] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0033] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0035] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0036] Example 1

[0037] refer to Figure 1 The reliable bypass flue gas evaporator automatic spray control system for thermal power units under deep peak shaving background described in this invention includes an inlet flue duct 1, a bypass flue gas evaporator 2, an outlet flue duct 3, a wastewater inlet pipe 4, a boiler load signal input terminal 5, an electric regulating valve control module for inlet water flow 6, an electric regulating valve feedback control module for inlet water flow 7, a flue gas flow meter 8, an outlet flue gas thermometer 9, an electromagnetic flow meter 10, an electric regulating valve for inlet water flow 11, a flue gas flow signal transmission system 12, an outlet temperature signal transmission system 13, a control system switcher 14, and a PID controller. A Controller 15 and PID B Controller 16;

[0038] The inlet flue 1 is connected to the inlet of the bypass flue gas evaporator 2, and the outlet of the bypass flue gas evaporator 2 is connected to the outlet flue 3. A flue gas flow meter 8 is installed on the inlet flue 1, and an outlet flue gas thermometer 9 is installed on the outlet flue 3. The outlet of the wastewater inlet pipe 4 is connected to the wastewater inlet of the bypass flue gas evaporator 2 via an electric regulating valve 11 and an electromagnetic flow meter 10.

[0039] The output of flue gas flow meter 8 is connected to the input of inlet water flow electric regulating valve control module 6 via flue gas flow signal transmission system 12. The output of inlet water flow electric regulating valve control module 6 is connected to the control terminal of inlet water flow electric regulating valve 11. The output of outlet flue gas thermometer 9 is connected to the input of inlet water flow electric regulating valve feedback control module 7 via outlet temperature signal transmission system 13. Boiler load signal input terminal 5 is connected to the input of control system switcher 14. The first output of control system switcher 14 is connected to the input of PIDA controller 15. The output of PIDA controller 15 is connected to the input of inlet water flow electric regulating valve feedback control module 7. The second output of control system switcher 14 is connected to the PIDA controller 15. A Connected to the input terminal of controller 15, PID B The output of controller 16 is connected to the input of the feedback control module 7 for electric regulating valve of inlet flow.

[0040] Example 2

[0041] The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units, as described in this invention, includes the following steps:

[0042] The inlet flow electric regulating valve control module 6 adjusts the opening degree L1 of the inlet flow electric regulating valve 11 according to the flue gas flow signal in the inlet flue duct 1 measured by the flue gas flow meter 8.

[0043] The inlet flow electric regulating valve feedback control module 7 calculates the deviation between the measured flue gas temperature in the outlet flue duct 3 and the set value Test based on the flue gas temperature measured by the outlet flue gas thermometer 9, and uses PID control based on the difference. A Controller 15 or PID B The proportional band value output by the controller 16 is used for PID calculation to obtain the compensation opening L2 of the electric regulating valve 11 for the inlet water flow.

[0044] Set the opening action threshold ΔL for the electric regulating valve 11 for the inlet flow rate. When L2 < ΔL, adjust the opening of the electric regulating valve 11 for the inlet flow rate to L1. When L2 ≥ ΔL, adjust the opening of the electric regulating valve 11 for the inlet flow rate to L = L1 + L2.

[0045] In addition, based on the characteristics of peak shaving in thermal power plant units, this invention incorporates a control system switcher 14 and a PID controller. A Controller 15 and PID B Controller 16; When the boiler load is >35%, the unit is considered to be in peak-shaving mode, and the unit load fluctuates frequently. The system then switches to PID control. A Controller 15, PID A The proportional band value δ output by controller 15 A The smaller the flow rate, the higher the system sensitivity and the faster the response, resulting in a better transient process curve. This allows the bypass flue gas evaporation system to adapt its water treatment capacity to unit load fluctuations. When the boiler load is ≤35%, the unit is considered to be in a low-load stable combustion state, and the system is relatively stable. Therefore, the system switches to PID control. B Controller 16, PID B The proportional band value δ output by controller 16 B It has a large capacity, stable system, slow feedback, and low sensitivity, which enables the bypass flue gas evaporation system to achieve stable operation under low load.

[0046] In one embodiment of the present invention, the value of L1 is in the range of 0% to 100%.

[0047] As one embodiment of the present invention, the ratio of the spray flow rate W1 to the inlet flue gas flow rate F1 should not exceed 1:15000, so that the sprayed water volume can roughly correspond to the extracted flue gas volume, the sprayed water volume is within a reasonable range, and the values ​​of F1 and W1 can be flexibly adjusted according to different unit conditions.

[0048] As one embodiment of the present invention, the given value of the opening degree L1 of the electric regulating valve 11 for the inlet flow rate is determined according to Table 1.

[0049] Table 1

[0050]

[0051] Where F1 takes values ​​ranging from 0 to 0 (Nm 3 / h)-60000 (Nm 3 The value of W1 can be adjusted according to the unit capacity; the ratio of the value of W1 to the value of F1 is no greater than 1:15000, so that the sprayed water volume roughly corresponds to the volume of flue gas extracted, and the sprayed water volume is within a reasonable range. The opening values ​​of the electric regulating valves 11 for inlet water flow, L01, L02, L03, L04..., range from 0% to 100%. The specific values ​​are determined according to the opening corresponding to the value of W1 during commissioning. All of the above values ​​can be flexibly adjusted according to the situation of different units, and there is no overlap between them.

[0052] Example 3

[0053] Taking the bypass flue gas evaporator of a 660MW unit in a power plant as an example, the control method of the present invention includes the following steps:

[0054] The inlet flow electric regulating valve control module 6 adjusts the opening degree L1 of the inlet flow electric regulating valve 11 according to the flue gas flow signal measured by the flue gas flow meter 8 and the preset flue gas flow.

[0055] The boiler load signal input terminal 5 sends the current boiler operating load signal to the control system switcher 14 for judgment. When the boiler load is >35% and there is a delay of 60 seconds, the unit is in peak shaving state, and the unit load fluctuates frequently. Therefore, the system switches to PID control. A Controller 15, PID A The proportional band value δ output by controller 15 A The smaller size of the bypass flue gas evaporation system results in high sensitivity and fast response, leading to a better transition curve and allowing the system to adapt its water treatment capacity to unit load fluctuations. When the boiler load is ≤35% with a 60s delay, the unit is in a low-load stable combustion state, and the system is relatively stable. Therefore, the system switches to PID control. B Controller 16, PID B The proportional band value δ output by controller 16B It has a large capacity, stable system, slow feedback, and low sensitivity, which enables the bypass flue gas evaporation system to achieve stable operation under low load.

[0056] The outlet flue gas temperature of the bypass flue gas evaporator 2 is set to 150℃. The feedback control module 7 of the electric regulating valve for the inlet water flow rate is based on the deviation between the temperature T measured by the outlet flue gas thermometer 9 and the set value of 150℃, and then by the currently selected PID controller. A Controller 15 or PID B The proportional band numerical calculation output by the controller 16 yields the compensation opening L2 of the electric regulating valve 11 for the inlet flow rate; wherein, the given value of the opening L1 of the electric regulating valve 11 for the inlet flow rate is determined according to Table 2.

[0057] Table 2

[0058]

[0059] The threshold value ΔL for the opening of the electric regulating valve 11 for the inlet flow rate is set. When L2 < ΔL, the opening of the electric regulating valve 11 for the inlet flow rate is adjusted to L1; when L2 ≥ ΔL, the opening of the electric regulating valve 11 for the inlet flow rate is adjusted to L = L1 + L2. Finally, within the spray flow rate range in Table 2, the spray water volume is calibrated and adjusted by fine-tuning the opening of the electric regulating valve 11 for the inlet flow rate, so that the outlet flue gas temperature is stabilized at 150℃, achieving a reasonable spray water volume and precise matching between the spray water volume and the volume of flue gas extracted.

[0060] The value of L1 ranges from 0% to 100%.

[0061] The ratio of the spray flow rate W1 to the inlet flue gas flow rate F1 is no greater than 1:15000, so that the sprayed water volume can roughly correspond to the extracted flue gas volume, and the sprayed water volume is within a reasonable range. Furthermore, the values ​​of F1 and W1 can be flexibly adjusted according to the different unit conditions.

[0062] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A reliable automatic spray control system for bypass flue gas evaporators under the background of deep peak shaving in thermal power units, characterized in that, Includes inlet flue (1), bypass flue gas evaporator (2), outlet flue (3), wastewater inlet pipeline (4), boiler load signal input terminal (5), inlet flow electric regulating valve control module (6), inlet flow electric regulating valve feedback control module (7), inlet flow electric regulating valve (11), control system switcher (14), PID A Controller (15) and PID B Controller (16); The inlet flue (1) is connected to the inlet of the bypass flue gas evaporator (2), and the outlet of the bypass flue gas evaporator (2) is connected to the outlet flue (3). A flue gas flow meter (8) is installed on the inlet flue (1), and an outlet flue gas thermometer (9) is installed on the outlet flue (3). The outlet of the wastewater inlet pipe (4) is connected to the wastewater inlet of the bypass flue gas evaporator (2) via an electric regulating valve (11). The output of the flue gas flow meter (8) is connected to the input of the inlet flow electric regulating valve control module (6), the output of the inlet flow electric regulating valve control module (6) is connected to the control of the inlet flow electric regulating valve (11), the output of the outlet flue gas thermometer (9) is connected to the input of the inlet flow electric regulating valve feedback control module (7), the boiler load signal input (5) is connected to the input of the control system switch (14), the first output of the control system switch (14) is connected to the input of the PIDA controller (15), the output of the PIDA controller (15) is connected to the input of the inlet flow electric regulating valve feedback control module (7), and the second output of the control system switch (14) is connected to the PIDA controller (15). A Connected to the input terminal of the controller (15), PID B The output of the controller (16) is connected to the input of the feedback control module (7) for the electric regulating valve of the inlet flow rate; The output end of the flue gas flow meter (8) is connected to the input end of the inlet water flow electric regulating valve control module (6) via the flue gas flow signal transmission system (12); The output of the outlet flue gas thermometer (9) is connected to the input of the inlet water flow electric regulating valve feedback control module (7) via the outlet temperature signal transmission system (13).

2. The reliable bypass flue gas evaporator automatic spray control system for thermal power units under deep peak shaving conditions as described in claim 1, characterized in that, The outlet of the wastewater inlet pipe (4) is connected to the wastewater inlet of the bypass flue gas evaporator (2) via the inlet flow electric regulating valve (11) and the electromagnetic flow meter (10).

3. A reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units, characterized in that, The reliable bypass flue gas evaporator automatic spray control system for thermal power units under the deep peak shaving background as described in claim 1 includes the following steps: The inlet flow electric regulating valve control module (6) adjusts the opening degree L1 of the inlet flow electric regulating valve (11) according to the flue gas flow signal in the inlet flue (1) measured by the flue gas flow meter (8); The feedback control module (7) for the electric regulating valve of the inlet water flow calculates the deviation between the measured flue gas temperature in the outlet flue (3) and the set value Test based on the flue gas temperature measured by the outlet flue gas thermometer (9), and uses PID control based on the deviation. A Controller (15) or PID B The proportional band value output by the controller (16) is used for PID calculation to obtain the compensation opening L2 of the electric regulating valve (11) for the inlet flow rate; Set the opening action threshold ΔL of the electric regulating valve (11) for the inlet flow rate. When L2 < ΔL, adjust the opening of the electric regulating valve (11) for the inlet flow rate to L1. When L2 ≥ ΔL, adjust the opening of the electric regulating valve (11) for the inlet flow rate to L = L1 + L2.

4. The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units according to claim 3, characterized in that, Also includes: When the boiler load is greater than 35%, the unit is considered to be in peak-shaving mode, and the unit load fluctuates frequently. The control system switch (14) switches to PID control. A Controller (15), PID A The proportional band value δ output by the controller (15) A Feedback control module (7) for electric regulating valve of inlet water flow; when the boiler load is ≤35%, it is considered that the unit is in a low load stable combustion state and the system is relatively stable. The control system switcher (14) switches to PID. B Controller (16), PID B The proportional band value δ output by the controller (16) B Feedback control module (7) for electric regulating valve of inlet water flow, wherein the proportional band value δ A Less than the value of the scale band δ B .

5. The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units according to claim 3, characterized in that, The value of L1 ranges from 0% to 100%.

6. The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units according to claim 3, characterized in that, The ratio of the spray flow rate W1 to the inlet flue gas flow rate F1 is no greater than 1:15000.

7. The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units according to claim 3, characterized in that, The output of the flue gas flow meter (8) is connected to the input of the inlet water flow electric regulating valve control module (6) via the flue gas flow signal transmission system (12).

8. The reliable automatic spray control method for bypass flue gas evaporators under the background of deep peak shaving in thermal power units according to claim 3, characterized in that, The output of the outlet flue gas thermometer (9) is connected to the input of the inlet water flow electric regulating valve feedback control module (7) via the outlet temperature signal transmission system (13).

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