An inner cooling water pH value intelligent adjusting device and an application method thereof

Abstract

The application discloses an intelligent pH adjusting device for inner cooling water and an application method thereof. The intelligent adjusting device comprises a pH meter before dosing, a conductivity meter before dosing, a control assembly, a metering pump, a lye tank, a conductivity meter after dosing and a pH meter after dosing. The output ends of the pH meter before dosing, the conductivity meter before dosing, the conductivity meter after dosing and the pH meter after dosing are connected with the control assembly. The output end of the lye tank is communicated with a circulating loop of the inner cooling water. The metering pump is installed on the output pipeline of the lye tank and the control end thereof is connected with the control assembly. The application can realize closed-loop control of adding lye in the circulating loop of the inner cooling water based on the pH values before and after dosing and the conductivities before and after dosing, can ensure the accurate amount of lye added when the water quality fluctuates, avoids the problems that the actual controlled pH value does not participate in control, the lye is not accurately added when the water quality fluctuates and the operation and maintenance rely on the experience of workers, and thus realizes precise intelligent automatic control of the pH of the inner cooling water.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of internal cooling water treatment of large generators and phase modulators of power systems, and in particular to an intelligent internal cooling water pH value adjusting device and an application method thereof. BACKGROUND

[0002] A large amount of heat is generated during the operation of large generators and phase modulators, which needs to be taken away by a cooling system. Water cooling is the most economical and effective way, and large generators and phase modulators generally adopt water cooling for cooling. In order to prevent the corrosion of the generator and phase modulator coil, the deposition of copper oxide, the influence on the heat transfer efficiency or the blockage of the coil and even the perforation leakage, which threatens the safe operation of the unit, the internal cooling water of the large generator and phase modulator has strict requirements on the water quality. The water quality requirements of the stator internal cooling water are that the pH value is 8.0-9.0, the copper ion content is less than 20 ug / L, and the electrical conductivity is less than 2.0 μS / cm, and the water quality requirements of the rotor internal cooling water are that the pH value is 7.0-9.0, the copper ion content is less than 40 ug / L (the expected value is 20 ug / L), and the electrical conductivity is less than 5.0 μS / cm.

[0003] In order to ensure the water quality of the internal cooling water, the most widely used and effective treatment method for the internal cooling water treatment is to purify the internal cooling water through a purification system and then to adjust the pH value by adding alkali. The internal cooling water of the generator and phase modulator adopts the method of adding sodium hydroxide to adjust the pH value of the internal cooling water, and the pH value control needs a corresponding pH adjusting device to ensure that the pH value is within the corresponding range. Since the pH value has a certain hysteresis due to the slow reaction speed, it cannot timely respond to the relationship between the dosage and the pH value, and cannot accurately control it. Since the electrical conductivity and the pH value have a certain corresponding correlation and are sensitive to the reaction, the addition of the corresponding alkali at the dosing point can be controlled to a certain electrical conductivity, that is, the difference between the electrical conductivity before and after the addition of the alkali at the dosing point determines the amount of the alkali added. The existing technology adjusts the pH of the internal cooling water by controlling the electrical conductivity of the dosing point, but this technology cannot automatically correct the target value according to the water quality fluctuation or the pH value of the internal cooling water to reach the target pH value. For example, when the internal cooling water quality fluctuates, the dosage will change with the change of the water quality electrical conductivity at the dosing point, which will eventually lead to the change of the pH value and make the pH value deviate from the target value. When the system is replenished with water or impurities such as carbon dioxide are dissolved during the operation, the water quality will change. Especially during the operation of the rotor internal cooling water system, a large amount of carbon dioxide is dissolved, the temperature and operating conditions are different, the amount of carbon dioxide dissolved is different, and the water quality changes greatly. At the same time, this adjusting method also depends on the technical experience of the operation and maintenance personnel, and the target value needs to be modified according to the water quality to ensure that the pH of the internal cooling water is controlled within the corresponding range. The application effect of the same technology in different places is also very different, which eventually leads to a large fluctuation range of the internal cooling water pH and a low water quality qualification rate. Therefore, an intelligent internal cooling water pH value adjusting device that can adapt to the fluctuation of the internal cooling water quality is needed. SUMMARY

[0004] The technical problem solved by the present application: In view of the above problems of the prior art, the present application provides an inner cooling water pH value intelligent adjusting device and an application method thereof. The present application can realize closed-loop control of adding alkali liquor on the circulation loop of the inner cooling water based on the pH values before and after adding the medicine and the conductivities before and after adding the medicine, can ensure the accurate amount of alkali liquor added when the water quality fluctuates, avoids the problems that the actual controlled pH value does not participate in the control and the alkali liquor is not accurately added when the water quality fluctuates and the operation and maintenance rely on the experience of the staff, and thus realizes the accurate intelligent automatic control of the pH of the inner cooling water.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] An inner cooling water pH value intelligent adjusting device, comprising a pH meter before adding medicine, a conductivity meter before adding medicine, a control assembly, a metering pump, an alkali liquor tank, a conductivity meter after adding medicine and a pH meter after adding medicine. The output ends of the pH meter before adding medicine, the conductivity meter before adding medicine, the conductivity meter after adding medicine and the pH meter after adding medicine are connected with the control assembly respectively. The output end of the alkali liquor tank is communicated with the circulation loop of the inner cooling water. The metering pump is installed on the output pipeline of the alkali liquor tank and the control end thereof is connected with the control assembly.

[0007] In addition, the present application further provides an inner cooling water circulation system, comprising an inner cooling water circulation loop composed of an inner cooling water tank and a purification assembly. The inner cooling water pH value intelligent adjusting device described above is installed on the inner cooling water circulation loop.

[0008] Optionally, the pH meter before adding medicine is installed on the pipeline between the output end of the inner cooling water tank and the input end of the purification assembly.

[0009] Optionally, the conductivity meter before adding medicine is installed upstream of the communication point between the output end of the alkali liquor tank and the circulation loop of the inner cooling water. The conductivity meter after adding medicine and the pH meter after adding medicine are installed downstream of the communication point between the output end of the alkali liquor tank and the circulation loop of the inner cooling water.

[0010] Optionally, the communication point between the output end of the alkali liquor tank and the circulation loop of the inner cooling water is located on the pipeline of the output end of the purification assembly.

[0011] In addition, the present application further provides an application method of the inner cooling water pH value intelligent adjusting device described above, comprising:

[0012] S101, controlling the output of the metering pump based on the difference between the conductivity before adding medicine and the preset target conductivity until the conductivity after adding medicine detected by the conductivity meter after adding medicine is equal to the target conductivity.

[0013] S102, judge whether the pH value detected by the post-dosing pH meter is equal to the preset target pH value, if yes, end and exit; otherwise, correct the target conductivity based on the difference between the pre-dosing pH value and the preset target pH value, and jump to step S101.

[0014] Optionally, in step S102, when correcting the target conductivity based on the difference between the pre-dosing pH value and the preset target pH value, if the pre-dosing pH value is lower than the preset target pH value, increase the value of the target conductivity by a specified step size, and if the pre-dosing pH value is higher than the preset target pH value, decrease the value of the target conductivity by a specified step size.

[0015] Optionally, the specified step size is 0.1 μS / cm.

[0016] Optionally, in step S101, the output of the metering pump is controlled based on the difference between the pre-dosing conductivity and the preset target conductivity by using PID control.

[0017] Optionally, the function expression of the PID control is:

[0018]

[0019] In the above formula, U(t) is the control voltage of the metering pump, err(t) is the difference between the pre-dosing conductivity and the preset target conductivity or the difference between the pre-dosing pH value and the preset target pH value, K p is the proportional coefficient, T I is the integral time coefficient, and T D is the differential time coefficient, and t is time.

[0020] Compared with the prior art, the present application has the following advantages: the pH value intelligent adjustment device for internal cooling water of the present application comprises a pre-dosing pH meter, a pre-dosing conductivity meter, a control assembly, a metering pump, a lye tank, a post-dosing conductivity meter and a post-dosing pH meter, the output ends of the pre-dosing pH meter, the pre-dosing conductivity meter, the post-dosing conductivity meter and the post-dosing pH meter are connected to the control assembly, the output end of the lye tank is in communication with the circulating loop of the internal cooling water, and the metering pump is installed on the output end pipeline of the lye tank and has a control end connected to the control assembly. The present application can realize closed-loop control of adding lye to the circulating loop of the internal cooling water based on the pre-dosing and post-dosing pH values and the pre-dosing and post-dosing conductivities, can ensure accurate addition of lye when the water quality fluctuates, and avoids the problems that the actual controlled pH value does not participate in control, the lye is not accurately added when the water quality fluctuates, and the operation and maintenance rely on the experience of the staff, thereby realizing precise, intelligent and automatic control of the pH value of the internal cooling water. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a structural schematic diagram of the internal cooling water pH value intelligent adjusting device and the internal cooling water circulation system of embodiment one of the present application.

[0022] Figure legend: 1, pH table before adding chemicals; 2, conductivity table before adding chemicals; 3, control assembly; 4, metering pump; 5, alkali tank; 6, conductivity table after adding chemicals; 7, pH table after adding chemicals; 8, internal cooling water tank; 9, purification assembly. DETAILED DESCRIPTION

[0023] Embodiment one:

[0024] The internal cooling water circulation system of the phase modifier stator will be taken as an example in the following to further explain the internal cooling water pH value intelligent adjusting device and the application method thereof. It should be noted that the internal cooling water circulation system of the phase modifier stator is similar to the internal cooling water circulation system of the generator stator in structure and property, and thus the present embodiment is also applicable to the internal cooling water circulation system of the generator stator.

[0025] Referring to Figure 1 , the internal cooling water pH value intelligent adjusting device of the present embodiment comprises a pH table 1 before adding chemicals, a conductivity table 2 before adding chemicals, a control assembly 3, a metering pump 4, an alkali tank 5, a conductivity table 6 after adding chemicals, and a pH table 7 after adding chemicals. The output ends of the pH table 1 before adding chemicals, the conductivity table 2 before adding chemicals, the conductivity table 6 after adding chemicals, and the pH table 7 after adding chemicals are connected to the control assembly 3 respectively. The output end of the alkali tank 5 is communicated with the circulation loop of the internal cooling water. The metering pump 4 is installed on the output end pipeline of the alkali tank 5 and the control end thereof is connected to the control assembly 3.

[0026] As shown in Figure 1 , the present embodiment further provides an internal cooling water circulation system, which comprises a circulation loop of the internal cooling water composed of an internal cooling water tank 8 and a purification assembly 9. The aforementioned internal cooling water pH value intelligent adjusting device is installed on the circulation loop of the internal cooling water.

[0027] As an optional embodiment, as shown in Figure 1 , the pH table 1 before adding chemicals of the present embodiment is installed on the pipeline between the output end of the internal cooling water tank 8 and the input end of the purification assembly 9.

[0028] As an optional embodiment, as shown in Figure 1 , the conductivity table 2 before adding chemicals of the present embodiment is installed upstream of the communication point between the output end of the alkali tank 5 and the circulation loop of the internal cooling water. The conductivity table 6 after adding chemicals and the pH table 7 after adding chemicals are installed downstream of the communication point between the output end of the alkali tank 5 and the circulation loop of the internal cooling water.

[0029] As an optional embodiment, as shown in Figure 1As shown, the output end of the alkali tank 5 of the embodiment is connected to the communication point of the circulating loop of the inner cooling water, which is located on the pipeline of the output end of the purification assembly 9.

[0030] In the embodiment, the conductivity meter used in the conductivity table 2 before dosing and the conductivity table 6 after dosing is a Hashi 8310 online pure water conductivity meter, the electrode constant is 0.00998, and the measurement error is 0.02 μS / cm. The pH meter used in the pH table 1 before dosing and the pH table 7 after dosing is a Hashi 8362 online pure water pH meter, and the error is 0.01. The metering pump 4 is a Rotem mikro delta electromagnetic drive variable frequency diaphragm precision metering pump, and the flow rate is 150-1500 mL / h. In addition, the control assembly 3 is realized based on Siemens STEP7-MicroWIN SMART (S7-1200) and its peripheral circuit.

[0031] In addition, the embodiment also provides an application method of the foregoing inner cooling water pH value intelligent adjusting device, which comprises the following steps:

[0032] S101, controlling the output of the metering pump 4 based on the difference between the conductivity before dosing and the preset target conductivity until the conductivity after dosing detected by the conductivity table 6 after dosing is equal to the target conductivity. For example, the preset target conductivity in the embodiment is 1.2 μS / cm, so that the conductivity of the inner cooling water after dosing is stabilized at 1.2 μS / cm through step S101.

[0033] S102, judging whether the pH value after dosing detected by the pH table 7 after dosing is equal to the preset target pH value, if yes, ending and exiting; otherwise, correcting the target conductivity based on the difference between the pH value before dosing and the preset target pH value, and jumping to step S101.

[0034] In the embodiment, when the target conductivity is corrected based on the difference between the pH value before dosing and the preset target pH value in step S102, if the pH value before dosing is lower than the preset target pH value, the value of the target conductivity is increased by a specified step length, and if the pH value before dosing is higher than the preset target pH value, the value of the target conductivity is decreased by a specified step length. The specified step length can be set according to needs, for example, as an optional implementation, the specified step length is 0.1 μS / cm. The control assembly 3 is not more than 2 μS / cm after dosing, and once the conductivity of the inner cooling water or the conductivity after dosing exceeds 2 μS / cm, the metering pump 4 should be stopped to prevent the conductivity of the inner cooling water from being too high due to dosing.

[0035] For example, the preset target pH value in the embodiment is 9.2. After the conductivity of the inner cooling water is stabilized at 1.2 μS / cm after the inner cooling water is dosed through step S101, the target value of the conductivity of the inner cooling water after dosing is further adjusted according to the pH value of the inner cooling water after dosing through step S102, so that the pH value after dosing is at 9.2: if the pH value is lower than 9.2, the target conductivity is gradually increased by 0.1 μS / cm to jump to step S101 until the pH value of the inner cooling water after dosing is stabilized at 9.2, and if the pH value is higher than 9.2, the target conductivity is gradually decreased by 0.1 μS / cm to jump to step S101 until the pH value of the inner cooling water after dosing is stabilized at 9.2.

[0036] In the embodiment, the output of the metering pump 4 is controlled based on the difference between the conductivity before dosing and the preset target conductivity in step S101, which means that the output of the metering pump 4 is controlled based on the difference between the conductivity before dosing and the preset target conductivity by using PID control. In the embodiment, the function expression of the PID control is as follows:

[0037]

[0038] In the above formula, U(t) is the control voltage of the metering pump 4 in the PID control output, err(t) refers to the difference between the conductivity before dosing and the preset target conductivity or the difference between the pH value before dosing and the preset target pH value, K p is a proportional coefficient, T I is an integral time coefficient, and T D is a differential time coefficient, and t is time. In the embodiment, K p = 0.48, T I = 0.10, and T D = 0.23.

[0039] It is tested that, by using the application method of the inner cooling water pH value intelligent adjustment device in the embodiment, the pH value of the inner cooling water of the stator can be stabilized and controlled at 8.5-8.7, the conductivity is 1.0-1.5 μS / cm, and the copper ion content is not detected. However, by using the conventional single conductivity control, the pH value is 7.5-8.5, the conductivity is 1.0-1.2 μS / cm, and the copper ion content is 10-40 μg / L. It can be seen that the application method of the inner cooling water pH value intelligent adjustment device in the embodiment can realize the precise intelligent automatic control of the pH value of the inner cooling water in the inner cooling water circulation system of the stator, and it can also be inferred that the application method of the inner cooling water pH value intelligent adjustment device in the embodiment can realize the precise intelligent automatic control of the pH value of the inner cooling water in the inner cooling water circulation system of the stator.

[0040] In summary, the application method of the inner cooling water pH intelligent adjusting device in the embodiment adjusts the inner cooling water pH by the method of correcting the conductivity mainly and the pH as an auxiliary, and adjusts the inner cooling water pH by monitoring the conductivity value before dosing in real time to ensure the accurate dosing amount of the lye when the water quality fluctuates, avoids the problems that the actual controlled pH value does not participate in the control, the lye is not accurately added when the water quality fluctuates, and the operation and maintenance rely on the experience of the staff, and thus realizes the accurate intelligent automatic control of the inner cooling water pH.

[0041] Embodiment two:

[0042] Hereinafter, the inner cooling water circulating system of the phase modifier rotor will be taken as an example to further illustrate the inner cooling water pH intelligent adjusting device and the application method thereof. It should be noted that the inner cooling water circulating system of the phase modifier rotor is similar to the inner cooling water circulating system of the generator rotor in structure and property, and thus the embodiment is also applicable to the inner cooling water circulating system of the generator rotor.

[0043] The method of the embodiment is basically similar to the method of embodiment one, and the main difference is that the control parameters of the PID control are optimized for the case that the inner cooling water of the inner cooling water circulating system of the phase modifier rotor fluctuates greatly, and specifically, K p = 0.452, T I = 0.20, and T D = 0.46 in the embodiment. In addition, the preset target conductivity in step S101 is 3.5 μS / cm, and thus the conductivity of the inner cooling water after dosing is stabilized at 3.5 μS / cm through step S101. The preset target pH value in step S102 is 8.5, and after the conductivity of the inner cooling water after dosing is stabilized at 3.5 μS / cm through step S101, the conductivity of the inner cooling water after dosing is further adjusted according to the pH value of the inner cooling water after dosing through step S102 to make the pH value after dosing be 8.5: if the pH value is lower than 8.5, the target conductivity is gradually increased by 0.1 μS / cm to jump to step S101 until the pH value of the inner cooling water after dosing is stabilized at 8.5, and if the pH value is higher than 8.5, the target conductivity is gradually reduced by 0.1 μS / cm to jump to step S101 until the pH value of the inner cooling water after dosing is stabilized at 8.5. Moreover, the conductivity of the inner cooling water after dosing of the control assembly 3 does not exceed 5 μS / cm, and once the conductivity of the inner cooling water or the conductivity after dosing exceeds 5 μS / cm, the metering pump is stopped to prevent the dosing from causing the conductivity of the inner cooling water to be too high.

[0044] Through the application method of the inner cooling water pH intelligent adjusting device in the embodiment, the pH value of the inner cooling water of the rotor can be controlled to be stable at 7.5-8.0, the conductivity is 2.8-4.5 μS / cm, and the copper ion content is less than 20 μg / L. However, when the conventional conductivity single control is adopted, the pH value is 6.5-8.0, the conductivity is 3.5-4.0 μS / cm, and the copper ion content is greater than 40 μg / L. It can be seen that the application method of the inner cooling water pH intelligent adjusting device in the embodiment can realize the precise intelligent automatic control of the pH of the inner cooling water in the inner cooling water circulation system of the rotor of the phase modifier, and it can also be inferred that the application method of the inner cooling water pH intelligent adjusting device in the embodiment can realize the precise intelligent automatic control of the pH of the inner cooling water in the inner cooling water circulation system of the rotor of the generator.

[0045] Similarly, the application method of the inner cooling water pH intelligent adjusting device in the embodiment adjusts the pH value of the inner cooling water by the method of taking the conductivity as the main factor and the pH as the auxiliary factor to correct the conductivity, and by monitoring the conductivity value before dosing in real time to ensure the accurate amount of alkali added when the water quality fluctuates, the problems that the actually controlled pH value does not participate in the control, the alkali is not accurately added when the water quality fluctuates, and the operation and maintenance rely on the experience of the staff are avoided, so that the precise intelligent automatic control of the pH of the inner cooling water is realized.

[0046] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as the protection scope of the present application.

Claims

1. An application method of an intelligent pH value regulating device for internal cooling water, characterized in that: The internal cooling water pH value intelligent regulating device comprises a pre-dosing pH meter (1), a pre-dosing conductivity meter (2), a control component (3), a metering pump (4), an alkali solution tank (5), a post-dosing conductivity meter (6), and a post-dosing pH meter (7), wherein the output ends of the pre-dosing pH meter (1), the pre-dosing conductivity meter (2), the post-dosing conductivity meter (6), and the post-dosing pH meter (7) are respectively connected to the control component (3), the output end of the alkali solution tank (5) is connected to the circulation loop of the internal cooling water, the metering pump (4) is installed on the output end pipeline of the alkali solution tank (5), and the control end is connected to the control component (3); the application method comprises: S101, controlling the output of the metering pump (4) based on the difference between the conductivity before dosing and the preset target conductivity until the conductivity after dosing detected by the conductivity meter (6) is equal to the target conductivity; S102, judging whether the pH value after drug addition detected by the pH meter (7) is equal to the preset target pH value, if it is equal to the preset target pH value, ending and exiting; otherwise, correcting the target conductivity based on the difference between the pH value before drug addition and the preset target pH value, and jumping to step S101; When the target conductivity is corrected based on the difference between the pH value before dosing and the preset target pH value in step S102, if the pH value before dosing is lower than the preset target pH value, the target conductivity value is increased by a specified step size; if the pH value before dosing is higher than the preset target pH value, the target conductivity value is decreased by a specified step size.

2. The application method of the internal cooling water pH value intelligent adjustment device according to claim 1, characterized in that: The specified step size is 0.1 μS / cm.

3. The application method of the internal cooling water pH value intelligent adjustment device according to claim 1, characterized in that: Controlling the output of the metering pump (4) based on the difference between the conductivity before dosing and the preset target conductivity in step S101 means using PID control to control the output of the metering pump (4) based on the difference between the conductivity before dosing and the preset target conductivity.

4. The application method of the internal cooling water pH value intelligent adjustment device according to claim 3, characterized in that: The functional expression of the PID control is: ， In the above formula, U ( t ) is the control voltage of the metering pump (4) output by PID control, err ( t ) refers to the difference between the conductivity before dosing and the preset target conductivity or the difference between the pH value before dosing and the preset target pH value, K p is the proportionality coefficient, T I is the integration time coefficient, T D is the differential time coefficient, t For time.

5. An internal cooling water circulation system for applying the method for applying the internal cooling water pH value intelligent adjustment device according to any one of claims 1 to 4, comprising an internal cooling water circulation loop consisting of an internal cooling water tank (8) and a purification component (9), characterized in that: The internal cooling water circulation loop is equipped with the internal cooling water pH value intelligent regulating device according to claim 1.

6. The internal cooling water circulation system according to claim 5, characterized in that: The pre-dosing pH meter (1) is installed on the pipeline between the output end of the internal cooling water tank (8) and the input end of the purification component (9).

7. The internal cooling water circulation system according to claim 6, characterized in that: The conductivity meter (2) before dosing is installed upstream of the connection point between the output end of the alkali liquid tank (5) and the internal cooling water circulation loop, and the conductivity meter (6) after dosing and the pH meter (7) after dosing are installed downstream of the connection point between the output end of the alkali liquid tank (5) and the internal cooling water circulation loop.

8. The internal cooling water circulation system according to claim 7, characterized in that: The connection point between the output end of the alkali liquid tank (5) and the internal cooling water circulation loop is located on the pipeline at the output end of the purification component (9).

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