A method and device for water injection temperature control of a superheater

Abstract

The application provides a superheater water injection temperature reduction control method and device, comprising: obtaining a feed water amount; obtaining a temperature reduction water amount; judging whether a relationship between the feed water amount and the temperature reduction water amount satisfies a first inequality; the first inequality is that a ratio of a pressure drop of a temperature reduction water regulating valve to a pressure drop of a temperature reduction water pipe is greater than or equal to a preset value; if yes, using a high-pressure heater outlet to supply temperature reduction water; if no, using a high-pressure heater inlet to supply temperature reduction water; according to a change relationship between the feed water amount and the temperature reduction water amount under different load conditions of a unit, performing disturbance-free switching of two temperature reduction water sources through logical control, so that economy and safety can be considered.

Description

Technical Field

[0001] This invention relates to the field of power plant boiler steam temperature regulation technology, and more specifically, to a method and device for superheater spray water de-cooling control. Background Technology

[0002] Water spray desuperheating is widely used as a primary method for regulating the temperature of superheated steam in power plant boilers. To ensure the superheated steam desuperheating water pressure meets the requirements for safe and stable operation, the superheated steam desuperheating water for 300MW units is mostly taken from before the high-pressure heater (hereinafter referred to as the PBH). However, this water intake point reduces the amount of regenerative steam extracted from the unit, leading to increased heat loss from the cold source and poor unit operating economy. If the superheated steam desuperheating water is taken from after the PBH, the amount of regenerative steam extracted increases, reducing the unit's cold source loss and improving unit economy. However, the pressure of the desuperheating water cannot be guaranteed, which may result in the superheated steam overheating due to insufficient desuperheating water.

[0003] In view of this, this application proposes a superheater spray water desuperheating control method and device, which can take into account both economy and safety. Water can be drawn from the high-pressure heater inlet (i.e., feed pump outlet) and the high-pressure heater outlet respectively, and two desuperheating water systems can be set up. According to the relationship between feed water volume and desuperheating water volume under different load conditions of the unit, the two desuperheating water sources can be switched seamlessly through logic control to achieve safe, economical and stable operation of the unit. Summary of the Invention

[0004] The purpose of this invention is to provide a superheater spray desuperheating control method, including obtaining the feed water volume; obtaining the desuperheating water volume; determining whether the relationship between the feed water volume and the desuperheating water volume satisfies a first inequality; the first inequality is that the ratio of the pressure drop of the desuperheating water regulating valve to the pressure drop of the desuperheating water pipe is greater than or equal to a preset value; if yes, then desuperheating water is supplied through the outlet of the high-pressure heater; if no, then desuperheating water is supplied through the inlet of the high-pressure heater.

[0005] Furthermore, the desuperheating water regulating valve is a first desuperheating water regulating valve, which is used to regulate the desuperheating water supplied from the outlet of the high-pressure heater.

[0006] Furthermore, the preset value is 0.3, and the first inequality is:

[0007]

[0008] Where X represents the feedwater flow rate; Y represents the desuperheating water flow rate; a represents the feedwater flow rate at rated flow; b represents the desuperheating water flow rate at rated flow; ΔP1 represents the feedwater flow rate orifice plate pressure drop; ΔP2 represents the economizer pressure drop; ΔP3 represents the pressure drop from the economizer to the steam drum connecting pipe; ΔP4 represents the pressure drop from the steam drum connecting pipe to the superheater desuperheating spray point; ΔP5 represents the first desuperheating water flow rate orifice plate pressure drop; ΔP6 represents the pressure drop required for water atomization at the first desuperheater nozzle; ∑ΔP G This represents the pressure drop in the water supply pipeline; ∑ΔP G′ This indicates the pressure drop in the first desuperheating water pipe.

[0009] Furthermore, the pressure drop ΔP7 required for water atomization at the nozzle of the first desuperheater is determined by the difference between the total pressure drop of the water supply pipe and the total pressure drop of the first desuperheating water pipe.

[0010] Furthermore, it includes a water supply pipe, a first desuperheating water pipe, and a second desuperheating water pipe; the water supply pipe includes at least a water supply pump and a high-pressure heater; the outlet of the water supply pump is connected to the inlet of the high-pressure heater; the first desuperheating water pipe is connected to the outlet of the high-pressure heater; and the second desuperheating water pipe is connected to the inlet of the high-pressure heater.

[0011] Furthermore, the water supply pipe also includes a water supply flow meter, an economizer, a steam drum connecting pipe, and a water spray point; the water supply pump includes multiple sub-water supply pumps, which are connected in parallel to deliver water to the water supply pipe; the high-pressure heater includes multiple sub-high-pressure heaters, which are connected in series, with one end receiving water output from the water supply pump and the other end delivering water to the water supply flow meter; the water passes through the water supply flow meter and sequentially through the economizer, the steam drum connecting pipe, and the water spray point.

[0012] Furthermore, the first desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; the water from the outlet of the high-pressure heater flows through the water supply flow meter in sequence through the first desuperheating water flow meter and the first desuperheating water regulating valve; the water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray the water to the spray point.

[0013] Furthermore, the first desuperheating water pipe also includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; the water from the outlet of the high-pressure heater flows through the water supply flow meter in sequence through the second desuperheating water flow meter and the second desuperheating water regulating valve; the water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray the water to the spray point.

[0014] Furthermore, the second desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; the water at the inlet of the high-pressure heater flows sequentially through the first desuperheating water flow meter and the first desuperheating water regulating valve; the water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray the water to the spray point.

[0015] Furthermore, the second desuperheating water pipe also includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; the water at the inlet of the high-pressure heater flows sequentially through the second desuperheating water flow meter and the second desuperheating water regulating valve; the water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray the water to the spray point.

[0016] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0017] Some embodiments in this manual can achieve seamless switching between two desuperheating water sources under different loads, thereby achieving the goal of safe, economical and stable operation of the unit. Attached Figure Description

[0018] Figure 1 An exemplary flowchart of a superheater spray desuperheating control method provided in some embodiments of the present invention;

[0019] Figure 2 This is an exemplary schematic diagram of a superheater spray desuperheating control device provided in some embodiments of the present invention;

[0020] Icons: 201-First sub-feed water pump, 202-Second sub-feed water pump, 203-Third sub-feed water pump, 204-First pressure measuring point, 205-Second pressure measuring point, 206-First sub-high pressure heater, 207-Second sub-high pressure heater, 208-Third sub-high pressure heater, 209-Third pressure measuring point, 210-Feed water flow meter, 211-Fifth pressure measuring point, 212-First desuperheater, 213-Second desuperheater, 214-Fourth pressure measuring point, 215-First desuperheating water flow meter, 216-First desuperheating water regulating valve, 217-Second desuperheating water flow meter, 218-Second desuperheating water regulating valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Figure 1This is an exemplary flowchart illustrating a superheater spray desuperheating control method provided in some embodiments of the present invention. In some embodiments, process 100 may be executed by device 200. Figure 1 As shown, process 100 includes the following steps:

[0023] Step 110: Obtain the water supply volume.

[0024] Feedwater volume refers to the amount of water supplied to the boiler. The unit for feedwater volume is tons. In some embodiments, the feedwater volume can be obtained using a feedwater flow meter. Figure 2 For example, the water supply volume is read from the water flow meter 210.

[0025] Step 120: Obtain the volume of water for cooling.

[0026] Desuperheating water volume refers to the amount of water used to cool water vapor. The unit for desuperheating water volume can be tons. In some embodiments, the desuperheating water volume can be obtained using a desuperheating water flow meter. Figure 2 For example, the first desuperheating water volume and the second desuperheating water volume can be read from the first desuperheating water flow meter 215 and the second desuperheating water flow meter 217, and then the sum of the first desuperheating water volume and the second desuperheating water volume can be used as the desuperheating water volume.

[0027] Step 130: Determine whether the relationship between the water supply and the desuperheating water volume satisfies the first inequality; the first inequality is that the ratio of the pressure drop of the desuperheating water regulating valve to the pressure drop of the desuperheating water pipe is greater than or equal to the preset value.

[0028] A desuperheating water regulating valve refers to a valve that adjusts the flow rate of desuperheating water. For example... Figure 2 As shown, the desuperheating water regulating valve may include a first desuperheating water regulating valve 216 and a second desuperheating water regulating valve 218. The pressure drop of the desuperheating water regulating valve may refer to the pressure drop across the first desuperheating water regulating valve 216 or the pressure drop across the second desuperheating water regulating valve 218. The desuperheating water pipe may refer to the pipe and components from the outlet of the feed water flow meter 210 to the first desuperheater 212 and the second desuperheater 213. The pressure drop of the desuperheating water pipe may refer to the pressure drop from the outlet of the feed water flow meter 210 to the outlet of the first desuperheater 212 or the outlet of the second desuperheater 213. The preset value may refer to the ratio of the pressure drop of the desuperheating water regulating valve to the pressure drop of the desuperheating water pipe, which is preset according to requirements. In some embodiments, when the ratio of the pressure drop of the desuperheating water regulating valve to the corresponding pressure drop of the desuperheating water pipe is greater than or equal to the preset value, it is determined that the relationship between the feed water flow and the desuperheating water flow satisfies the first inequality.

[0029] In some embodiments, only the ratio of the pressure drop across the first desuperheating water regulating valve 216 to the pressure drop in the first desuperheating water pipe needs to be calculated. When the pressure drop ratio is greater than or equal to 0.3, it is determined that the relationship between the water supply and the desuperheating water volume satisfies the first inequality. The first desuperheating water regulating valve is used to regulate the desuperheating water supplied from the outlet of the high-pressure heater.

[0030] In some embodiments, the first inequality is:

[0031]

[0032] Where X represents the feedwater flow rate; Y represents the desuperheating water flow rate; a represents the feedwater flow rate at rated flow; b represents the desuperheating water flow rate at rated flow; ΔP1 represents the feedwater flow rate orifice plate pressure drop; ΔP2 represents the economizer pressure drop; ΔP3 represents the pressure drop from the economizer to the steam drum connecting pipe; ΔP4 represents the pressure drop from the steam drum connecting pipe to the superheater desuperheating spray point; ΔP5 represents the first desuperheating water flow rate orifice plate pressure drop; ΔP6 represents the pressure drop required for water atomization at the first desuperheater nozzle; ∑ΔP G This represents the pressure drop in the water supply pipeline; ∑ΔP G′ This indicates the pressure drop in the first desuperheating water pipe.

[0033] The feedwater flow rate at rated flow rate can refer to the amount of water required to generate the maximum amount of steam when the device is operating continuously under design conditions. The desuperheating water flow rate at rated flow rate can refer to the amount of desuperheating water required to cool the maximum amount of steam that can be generated. a and b can be obtained from the equipment parameters. The feedwater flow orifice plate pressure drop can refer to the pressure drop of the feedwater flow meter 210. The feedwater flow orifice plate pressure drop can be obtained by reading the pressure between the second pressure measuring point 205 and the third pressure measuring point 209. The sum of the economizer pressure drop ΔP2, the economizer-to-steam drum connecting pipe pressure drop ΔP3, and the steam drum connecting pipe-to-superheater desuperheating spray point pressure drop ΔP4 can be obtained by reading the pressure at the third pressure measuring point 209 and the fifth pressure measuring point 211. In some embodiments, the pressure drop ΔP6 required to atomize water at the first desuperheater nozzle can be obtained from the total pressure drop ΔP of the feedwater pipe. Z The total pressure drop ΔP of the first desuperheating water pipe j1 The difference is determined, that is:

[0034] ΔP6=ΔP Z -ΔP j1

[0035] Total pressure drop ΔP in the water pipe Z It can be determined by the following formula:

[0036] ΔP Z =ΔP1+ΔP2+ΔP3+ΔP4+ΔP7+∑ΔP G

[0037] Here, ΔP7 represents the pressure drop of the high-pressure heater. The pressure drop of the high-pressure heater can be obtained by reading the pressure at the first pressure measurement point 204 and the second pressure measurement point 205.

[0038] The total pressure drop ΔP in the first cooling water pipe j1It can be determined by the following formula:

[0039] ΔP j1 =ΔP5 + ΔP7 + ΔP v +∑ΔP G′

[0040] Where, ΔP v To reduce the operating pressure drop of the heated water regulating valve.

[0041] The first inequality can be expressed as the ratio of the pressure drop of the first desuperheating water regulating valve to the pressure drop of the desuperheating water pipe, S≥0.3. This is because when S≥0.3, the flow characteristics of the desuperheating water regulating valve can meet the requirements; when S<0.3, the flow characteristics of the regulating valve are greatly distorted, making it unsuitable for control and unable to meet the requirements of the desuperheating water volume.

[0042] To ensure that S≥0.3, then P∝Q 2 Where P represents pressure drop and Q represents flow rate, the following formula can be obtained:

[0043]

[0044]

[0045]

[0046] Step 140: If the relationship between the water supply and the desuperheating water supply satisfies the first inequality, then the desuperheating water is supplied from the outlet of the high-pressure heater. This ensures that S≥0.3, thus guaranteeing both safety and economic efficiency.

[0047] Step 150: If the relationship between the water supply and the desuperheating water supply does not satisfy the first inequality, then the desuperheating water is supplied through the inlet of the high-pressure heater, so that the safe operation of the device can be guaranteed by sacrificing economic efficiency.

[0048] Figure 2 This is an exemplary schematic diagram of a superheater spray desuperheating control device provided for some embodiments of the present invention. Figure 2 As shown, the superheater spray desuperheating control device 200 includes a water supply pipe, a first desuperheating water pipe, and a second desuperheating water pipe.

[0049] The water supply pipe includes at least a water supply pump and a high-pressure heater; the outlet of the water supply pump is connected to the inlet of the high-pressure heater.

[0050] like Figure 2As shown, in some embodiments, the water supply pump may include multiple sub-water supply pumps, which are connected in parallel to deliver water to the water supply pipeline. For example, the water supply pump may include a first sub-water supply pump 201, a second sub-water supply pump 202, and a third sub-water supply pump 203. The water pumped in by each sub-water supply pump passes through a check valve and an electric shut-off valve respectively before being combined, and then the combined water is fed into the high-pressure heater through the electric shut-off valve.

[0051] In some embodiments, the high-pressure heater may include multiple sub-high-pressure heaters connected in series, one end of which receives water output from the feedwater pump, and the other end of which delivers the water to the feedwater flow meter. Figure 2 For example, the high-pressure heater may include a first sub-high-pressure heater 206, a second sub-high-pressure heater 207 and a third sub-high-pressure heater 208. The water output from the water pump can flow through the three sub-high-pressure heaters in sequence via an electric shut-off valve, and then be input into the water flow meter 210 via the electric shut-off valve.

[0052] Water flowing out from the feedwater flow meter 210 is converted into steam by the economizer, and then the steam is transported to the spray point through the steam drum connecting pipe to cool the steam at the spray point by the desuperheater.

[0053] The first desuperheating water pipe is connected to the outlet of the high-pressure heater.

[0054] In some embodiments, the first desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; water from the high-pressure heater outlet flows sequentially through the feed water flow meter, the first desuperheating water flow meter, and the first desuperheating water regulating valve; water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray water to the spray point. In some embodiments, the first desuperheating water pipe further includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; water from the high-pressure heater outlet flows sequentially through the feed water flow meter, the second desuperheating water flow meter, and the second desuperheating water regulating valve; water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray water to the spray point. Figure 2 For example, a portion of the water flowing out of the water supply flow meter 210 flows sequentially through a manual shut-off valve, an electric shut-off valve, and a check valve into the first desuperheating water flow meter 215 and the second desuperheating water flow meter 217. Then, the water flowing out of the first desuperheating water flow meter 215 flows sequentially through the first desuperheating water inlet valve, the first desuperheating water regulating valve 216, and the first desuperheating water outlet valve until it flows into the first desuperheater 212. Finally, the first desuperheater 212 sprays water to the spray point to cool the water vapor. The water flowing out of the second desuperheating water flow meter 217 flows sequentially through the second desuperheating water inlet valve, the second desuperheating water regulating valve 218, and the second desuperheating water outlet valve until it flows into the second desuperheater 213. Finally, the second desuperheater 213 sprays water to the spray point to cool the water vapor.

[0055] The second desuperheating water pipe is connected to the inlet of the high-pressure heater.

[0056] In some embodiments, the second desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; water from the inlet of the high-pressure heater flows sequentially through the first desuperheating water flow meter and the first desuperheating water regulating valve; water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray water to the spray point. In some embodiments, the second desuperheating water pipe further includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; water from the inlet of the high-pressure heater flows sequentially through the second desuperheating water flow meter and the second desuperheating water regulating valve; water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray water to the spray point. Figure 2 For example, a portion of the water at the inlet of the high-pressure heater (i.e., the water output from the feed pump) flows through the electric shut-off valve into the first desuperheating water flow meter 215 and the second desuperheating water flow meter 217. Then, the water flowing out of the first desuperheating water flow meter 215 flows sequentially through the first desuperheating water inlet valve, the first desuperheating water regulating valve 216, and the first desuperheating water outlet valve until it flows into the first desuperheater 212. Finally, the first desuperheater 212 sprays water to the spray point to cool the steam. Similarly, the water flowing out of the second desuperheating water flow meter 217 flows sequentially through the second desuperheating water inlet valve, the second desuperheating water regulating valve 218, and the second desuperheating water outlet valve until it flows into the second desuperheater 213. Finally, the second desuperheater 213 sprays water to the spray point to cool the steam. Figure 2 In the middle section, the low-temperature superheater is the low-temperature superheater, the high-temperature superheater is the high-temperature superheater, the partition screen is the partition screen superheater, and the rear screen is the rear screen superheater.

[0057] In some embodiments, in order to measure the pressure drop in the pipeline, a first pressure measuring point 204 is provided at the outlet of the water pump, a second pressure measuring point 205 is provided at the outlet of the high-pressure heater, a third pressure measuring point 209 is provided at the outlet of the water flow meter 210, a fourth pressure measuring point 214 is provided at the common inlet of the first desuperheating water flow meter 215 and the second desuperheating water flow meter 217, and a fifth pressure measuring point 211 is provided after the low-temperature superheater.

[0058] The superheated water spray desuperheating control method and device proposed in this application only requires adding one desuperheating water pipeline to the boiler-side feedwater header. The control module determines the relationship between the feedwater volume and the desuperheating water volume, enabling seamless switching between the two desuperheating water sources. It maintains the safety of traditional water spray desuperheating systems while solving the problem of insufficient desuperheating water pressure and spray volume under certain loads when the desuperheating water is taken from the high-pressure heater outlet, thus maximizing safety and economy. The system has a simple structure, requires less investment, and plays a significant role in reducing coal consumption for power generation and carbon emissions from thermal power units.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling superheater water spray desuperheating, characterized in that, include Obtain water supply volume; Obtain the volume of cooling water; Determine whether the relationship between the water supply and the desuperheating water volume satisfies the first inequality; the desuperheating water regulating valve is the first desuperheating water regulating valve, which is used to regulate the desuperheating water supplied from the outlet of the high-pressure heater; the first inequality is: Where X represents the water supply volume; Y represents the desuperheating water volume; a represents the water supply volume at rated flow rate; b represents the desuperheating water volume at rated flow rate; Indicates the pressure drop across the orifice plate at the water supply flow rate; Indicates the economizer pressure drop; This indicates the pressure drop in the connecting pipe between the economizer and the steam drum; This indicates the pressure drop from the steam drum connecting pipe to the superheater desuperheating spray point; This indicates the pressure drop across the orifice plate at the first desuperheating water flow rate; This indicates the pressure drop required to atomize water at the nozzle of the first desuperheater; Indicates the pressure drop in the water supply pipeline; This indicates the pressure drop in the first desuperheating water pipe; the pressure drop required at the nozzle of the first desuperheater to atomize the water. It is determined by the difference between the total pressure drop of the water supply pipe and the total pressure drop of the first desuperheating water pipe; If so, then the desuperheating water is supplied from the outlet of the high-pressure heater; If not, then the desuperheating water is supplied through the inlet of the high-pressure heater.

2. A superheater spray water desuperheating control device, characterized in that, The method for implementing the superheater spray desuperheating control method as described in claim 1 includes a water supply pipe, a first desuperheating water pipe, and a second desuperheating water pipe. The water supply pipe includes at least a water supply pump and a high-pressure heater; the outlet of the water supply pump is connected to the inlet of the high-pressure heater; The first desuperheating water pipe is connected to the outlet of the high-pressure heater; The second desuperheating water pipe is connected to the inlet of the high-pressure heater.

3. The superheater spray desuperheating control device according to claim 2, characterized in that, The water supply pipe also includes a water flow meter, an economizer, a steam drum connecting pipe, and water spray points; The water supply pump includes multiple sub-water supply pumps, which are connected in parallel to deliver water to the water supply pipeline. The high-pressure heater includes multiple sub-high-pressure heaters connected in series. One end of the sub-high-pressure heaters receives water output from the water pump, and the other end delivers water to the water flow meter. Water passes through the feedwater flow meter in sequence through the economizer, the steam drum connecting pipe, and the water spray point.

4. The superheater spray desuperheating control device according to claim 2, characterized in that, The first desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; The water from the outlet of the high-pressure heater flows sequentially through the first desuperheating water flow meter and the first desuperheating water regulating valve after passing through the water supply flow meter. Water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray water to the spray point.

5. The superheater spray desuperheating control device according to claim 4, characterized in that, The first desuperheating water pipe also includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; The water from the outlet of the high-pressure heater flows through the feed water flow meter, then sequentially through the second desuperheating water flow meter and the second desuperheating water regulating valve. Water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray water to the spray point.

6. The superheater spray desuperheating control device according to claim 2, characterized in that, The second desuperheating water pipe includes at least a first desuperheating water flow meter, a first desuperheating water regulating valve, and a first desuperheater; The water at the inlet of the high-pressure heater flows sequentially through the first desuperheating water flow meter and the first desuperheating water regulating valve. Water flowing through the first desuperheating water regulating valve flows into the first desuperheater to spray water to the spray point.

7. The superheater spray desuperheating control device according to claim 6, characterized in that, The second desuperheating water pipe also includes a second desuperheating water flow meter, a second desuperheating water regulating valve, and a second desuperheater; The water at the inlet of the high-pressure heater flows sequentially through the second desuperheating water flow meter and the second desuperheating water regulating valve; Water flowing through the second desuperheating water regulating valve flows into the second desuperheater to spray water to the spray point.

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