Method for inhibiting fluctuation of pH value of boiler feed water

Abstract

The invention relates to a method for inhibiting the fluctuation of the pH value of boiler feed water, and the method enables the setting position of a first detection point to be close to a precision treatment ammonification point, can reduce the delay during the detection of the conductivity, enables the detected conductivity to be more accurate, can improve the ammonification accuracy of an ammonification unit, and improves the accuracy of the pH value control of the boiler feed water. Moreover, the frequency of the ammonia adding pump is adjusted according to the comparison result of the real-time conductivity of the condensed water at the first detection point and the standard conductivity, so that the real-time conductivity of the condensed water fluctuates in a narrow range, and the stability of boiler feed water pH control can be improved. In addition, by adopting the method disclosed by the invention, the pH adjustment can be completed at the fine treatment ammonia adding point, the use frequency of associated equipment and pipelines at the water supply ammonia adding point can be reduced, and the complexity of pH adjustment is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of power plant boilers, and in particular, to a method for suppressing fluctuations in pH value of boiler feed water. Background Art

[0002] Water quality control of boiler feed water system is an indispensable link in thermal power plants, and feed water pH control is a particularly important point in the whole link, laying the foundation for the long-term safe operation of the unit; the condensate automatic ammonia addition device is used to adjust the pH value of boiler feed water, so that the pH value of boiler feed water is maintained within the optimal range, thereby preventing acid-base corrosion of boilers and other thermal equipment caused by pH imbalance of feed water, making the thermal system work in the best state, and ensuring the long-term, safe and stable operation of thermal equipment.

[0003] In the domestic market, there are usually methods that directly use pH signals to control the amount of ammonia added, use feed water flow signals as the main adjustment signals, and use feed water conductivity or pH as auxiliary signals to control the amount of ammonia added, etc., but automatic ammonia adding devices that directly use conductivity signals to control the amount of ammonia added to adjust the pH of feed water are widely used in the market. Although the condensate automatic ammonia adding device used in the prior art can control the pH value of feed water within a certain range, in actual application, especially when the unit is in deep peak regulation, rapid load increase and decrease and other special working conditions, the automatic ammonia adding device has poor automatic adjustment stability performance, and often over- or under-addition of ammonia occurs, resulting in large fluctuations in the pH value of boiler feed water, and the pH value index frequently exceeds the national standard range. Such long-term operation is likely to destroy the protective film formed on the metal inner wall surface of the thermal system, increase the corrosion rate, the shedding of corrosion products, increase the probability of boiler tube burst, implicitly increase the energy consumption of the unit, and is not conducive to the economic, safe and stable operation of the unit. Summary of the invention

[0004] The purpose of the present disclosure is to provide a method for suppressing fluctuations in the pH value of boiler feed water, so as to solve the problem of poor stability of feed water pH control in the prior art.

[0005] In order to achieve the above object, the present disclosure provides a method for suppressing fluctuations in pH value of boiler feed water, the method comprising: The condensate produced by the condenser is treated by a fine treatment device and then mixed with an ammonia solution of an ammonia adding unit for pH adjustment treatment, and the obtained condensate is sent to a deaerator for deoxygenation treatment to obtain boiler feed water; The ammonia addition unit comprises an ammonia solution tank, an ammonia addition pump, an ammonia addition control device and an ammonia addition main line; the inlet of the ammonia solution tank is used to communicate with an ammonia solution source, and the outlet of the ammonia solution tank is communicated with the inlet of the ammonia addition pump; the outlet of the ammonia addition pump is communicated with the inlet pipeline of the deaerator through the ammonia addition main line; the connection point between the ammonia addition main line and the inlet pipeline of the deaerator is a fine treatment ammonia addition point; The pH adjustment process comprises: The ammonia addition control device is configured to control the condensate water at the first detection point according to the real-time conductivity of the condensate water. With standard conductivity The comparison result adjusts the frequency of the ammonia adding pump; Wherein, the first detection point is arranged on the inlet pipeline of the deaerator, and the ratio of the pipeline length between the fine treatment ammonia addition point and the inlet of the deaerator to the pipeline length between the fine treatment ammonia addition point and the first detection point is (3.5-5):1; The standard conductivity It is 5.8~6.5μS / cm.

[0006] Optionally, the ratio of the pipeline length between the fine treatment ammonia addition point and the inlet of the deaerator to the pipeline length between the fine treatment ammonia addition point and the first detection point is (4~4.5):1.

[0007] Optionally, the standard conductivity of the boiler feed water is It is 6.0~6.4μS / cm.

[0008] Optionally, the ammonia addition control device includes an automatic control cabinet and a first conductivity meter; the first conductivity meter is arranged at the first detection point, and is used to detect the conductivity of the condensed water at the first detection point; the automatic control cabinet is electrically connected to the first conductivity meter and the ammonia addition pump, and is used to receive the conductivity signal of the first conductivity meter and adjust the frequency of the ammonia addition pump according to the conductivity signal.

[0009] Optionally, the adjustment frequency of the automatic control cabinet is 3 to 6 minutes per time.

[0010] Optionally, the adjustment frequency of the automatic control cabinet is 5 minutes per time.

[0011] Optionally, the pH adjustment process further comprises: when the real-time conductivity of the condensed water at the first detection point is In the standard conductivity When the real-time conductivity of the condensate at the first detection point is Less than the standard conductivity When the ammonia adding pump is increased to a fixed frequency.

[0012] Optionally, the fixed frequency is 1~3 Hz.

[0013] Optionally, the fixed frequency is 2 Hz.

[0014] Optionally, the ammonia adding pump comprises a first ammonia adding pump and a second ammonia adding pump arranged in parallel; When the first ammonia adding pump fails, the second ammonia adding pump is switched so that the ammonia solution in the ammonia solution tank enters the ammonia adding main path under the action of the second ammonia adding pump; When the second ammonia adding pump fails, the first ammonia adding pump is switched so that the ammonia solution in the ammonia solution tank enters the ammonia adding main path under the action of the first ammonia adding pump.

[0015] Through the above technical solution, the first detection point is set close to the fine treatment ammonia addition point, which can reduce the delay in detecting conductivity and make the detected conductivity more accurate, thereby improving the accuracy of ammonia addition by the ammonia addition unit, so as to improve the accuracy of boiler feed water pH control. In addition, the frequency of the ammonia addition pump is adjusted according to the comparison result between the real-time conductivity of the condensate water at the first detection point and the standard conductivity, so that the real-time conductivity of the condensate water fluctuates within a narrow range, which can improve the stability of boiler feed water pH control. In addition, the method disclosed in the present invention can complete pH adjustment at the fine treatment ammonia addition point, which can reduce the frequency of use of associated equipment and pipelines at the feed water ammonia addition point and reduce the complexity of pH adjustment.

[0016] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 Schematic diagram of a method for suppressing pH fluctuation of boiler feed water disclosed in the present invention.

[0018] Description of Reference Numerals 1 Condenser; 2 Condensate pump; 3 Polishing device; 4 Deaerator; 5 Polishing ammonia adding point; 6 First detection point; 7 Second detection point; 8 Ammonia solution tank; 9 First ammonia adding pump; 10 Second ammonia adding pump; 11 Ammonia adding main line; 12 Automatic control cabinet; 13 First conductivity meter; 14 Second conductivity meter; 15 Water supply ammonia adding point; 16 First water supply ammonia adding pump; 17 Second water supply ammonia adding pump. DETAILED DESCRIPTION

[0019] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0020] like Figure 1 As shown, the present disclosure provides a method for suppressing fluctuations in pH value of boiler feed water, the method comprising: The condensate produced by the condenser 1 is treated by the fine treatment device 3 and then mixed with the ammonia solution of the ammonia adding unit for pH adjustment treatment, and the obtained condensate is sent to the deaerator 4 for deoxygenation treatment to obtain boiler feed water; The ammonia addition unit includes an ammonia solution tank 8, an ammonia addition pump, an ammonia addition control device and an ammonia addition main path 11; the inlet of the ammonia solution tank 8 is used to communicate with the ammonia solution source, and the outlet of the ammonia solution tank 8 is communicated with the inlet of the ammonia addition pump; the outlet of the ammonia addition pump is communicated with the inlet pipeline of the deaerator 4 through the ammonia addition main path 11; the connection point between the ammonia addition main path 11 and the inlet pipeline of the deaerator 4 is the fine treatment ammonia addition point 5; The pH adjustment process comprises: The ammonia addition control device is configured to control the real-time conductivity of the condensed water at the first detection point 6. With standard conductivity The comparison result adjusts the frequency of the ammonia adding pump; Wherein, the first detection point 6 is arranged on the inlet pipeline of the deaerator 4, and the ratio of the pipeline length between the fine treatment ammonia addition point 5 and the inlet of the deaerator 4 to the pipeline length between the fine treatment ammonia addition point 5 and the first detection point 6 is (3.5-5):1; The standard conductivity It is 5.8~6.5μS / cm.

[0021] Through the above technical solution, the first detection point 6 is set close to the fine treatment ammonia addition point 5, which can reduce the delay in detecting conductivity and make the detected conductivity more accurate, thereby improving the accuracy of ammonia addition by the ammonia addition unit, so as to improve the accuracy of boiler feed water pH control. In addition, the frequency of the ammonia addition pump is adjusted according to the comparison result between the real-time conductivity of the condensate water at the first detection point 6 and the standard conductivity, so that the real-time conductivity of the condensate water fluctuates within a narrow range, which can improve the stability of boiler feed water pH control. In addition, the method disclosed in the present invention can complete pH adjustment at the fine treatment ammonia addition point, which can reduce the frequency of use of associated equipment and pipelines at the feed water ammonia addition point and reduce the complexity of pH adjustment.

[0022] In one embodiment, a condensate pump 2 is provided between the condenser 1 and the polishing device 3 to transport the condensed water generated by the condenser 1 to the polishing device 3 .

[0023] In a preferred embodiment, the ratio of the pipeline length between the fine treatment ammonia addition point 5 and the inlet of the deaerator 4 to the pipeline length between the fine treatment ammonia addition point 5 and the first detection point 6 is (4~4.5):1.

[0024] In this embodiment, the fine treatment ammonia addition point 5 and the first detection point 6 are respectively set at appropriate positions. On the one hand, the mixed liquid at the fine treatment ammonia addition point 5 can be fully mixed when it flows to the first detection point 6, so that the conductivity measured at the first detection point 6 is more accurate, and the accuracy of the boiler feed water pH control is further improved; on the other hand, the delay of the conductivity detection of the mixed liquid at the first detection point 6 can be reduced, so that the conductivity detected by the first detection point 6 is closer to the conductivity of the condensate at the fine treatment ammonia addition point 5, and the amount of ammonia addition can be adjusted at the first time when the pH value of the condensate is detected to be abnormal, thereby improving the stability of the boiler feed water pH control.

[0025] In one embodiment, the ammonia adding pump comprises a first ammonia adding pump 9 and a second ammonia adding pump 10 arranged in parallel; When the first ammonia adding pump 9 fails, the second ammonia adding pump 10 is switched so that the ammonia solution in the ammonia solution tank 8 enters the ammonia adding main path 11 under the action of the second ammonia adding pump 10; When the second ammonia adding pump 10 fails, the first ammonia adding pump 9 is switched so that the ammonia solution in the ammonia solution tank 8 enters the ammonia adding main path 11 under the action of the first ammonia adding pump 9 .

[0026] In one embodiment, the first ammonia pump 9 and the second ammonia pump 10 are conventionally selected in the art, and this application does not make special requirements. The first ammonia pump 9 and the second ammonia pump 10 with different maximum frequencies are flexibly selected according to actual production needs.

[0027] In a preferred embodiment, the ratio of the maximum frequencies of the first ammonia adding pump 9 and the second ammonia adding pump 10 is 1: 1. In this embodiment, since one of the first ammonia adding pump 9 and the second ammonia adding pump 10 is used as the main ammonia adding pump and the other is used as the backup ammonia adding pump, when one of the ammonia adding pumps is abnormal, the other ammonia adding pump is switched, which can extend the service life of the ammonia adding unit and enable maintenance without stopping the machine.

[0028] In one embodiment, the ammonia solution tank 8 described in the present disclosure is a conventional choice in the art, and this application does not make any special requirements. In addition, the concentration of the ammonia solution configured in the ammonia solution tank 8 can be flexibly set according to actual production needs.

[0029] In one embodiment, the ammonia addition control device includes an automatic control cabinet 12 and a first conductivity meter 13; the first conductivity meter 13 is set at the first detection point 6, and is used to detect the conductivity of the condensed water at the first detection point 6; the automatic control cabinet 12 is electrically connected to the first conductivity meter 13 and the ammonia addition pump, and is used to receive the conductivity signal of the first conductivity meter 13, and adjust the frequency of the ammonia addition pump according to the conductivity signal.

[0030] In one embodiment, the automatic control cabinet 12 described in the present disclosure is a conventional choice in the art, and this application does not make any special requirements, as long as the method of the present disclosure can be executed.

[0031] In one implementation, the first conductivity meter 13 is a conventional choice in the art and is not specifically required in this application.

[0032] In one embodiment, one or more of a shut-off valve, a check valve and a flow regulating valve may be respectively arranged at appropriate positions on each pipeline of the ammonia adding unit to flexibly adjust the flow of the ammonia solution in each pipeline.

[0033] In a preferred embodiment, the standard conductivity of the boiler feed water is In this embodiment, the standard conductivity of the boiler feed water can be flexibly adjusted according to the pH value allowed by the boiler feed water. For example, the standard conductivity of the boiler feed water can be any one of 6.0 μS / cm, 6.1 μS / cm, 6.2 μS / cm, 6.3 μS / cm and 6.4 μS / cm, or any two of them. Among them, the pH value corresponding to the boiler feed water with a standard conductivity of 5.8μS / cm is 9.333, the pH value corresponding to the boiler feed water with a standard conductivity of 5.9μS / cm is 9.341, the pH value corresponding to the boiler feed water with a standard conductivity of 6.0μS / cm is 9.348, the pH value corresponding to the boiler feed water with a standard conductivity of 6.1μS / cm is 9.355, the pH value corresponding to the boiler feed water with a standard conductivity of 6.2μS / cm is 9.362, the pH value corresponding to the boiler feed water with a standard conductivity of 6.3μS / cm is 9.369, the pH value corresponding to the boiler feed water with a standard conductivity of 6.4μS / cm is 9.376, and the pH value corresponding to the boiler feed water with a standard conductivity of 6.5μS / cm is 9.383.

[0034] In one implementation, the adjustment frequency of the automatic control cabinet 12 is 3 to 6 minutes per time.

[0035] In a preferred implementation, the adjustment frequency of the automatic control cabinet 12 is 5 minutes per time.

[0036] In this embodiment, the adjustment frequency of the automatic control cabinet 12 is the frequency of the pH adjustment treatment. By selecting a suitable refresh frequency, it is possible to adjust in time when the conductivity of the condensate water is abnormal, thereby further improving the stability of the pH control of the boiler feed water. In addition, after the frequency of the ammonia pump is adjusted, the reaction time of the ammonia treatment is basically completed within 300 seconds, and the cycle interval is shortened by 900 seconds compared with 1200 seconds in the prior art.

[0037] In one embodiment, the pH adjustment process further comprises: When the real-time conductivity of the condensed water at the first detection point 6 is In the standard conductivity When the above, the ammonia pump is reduced by a fixed frequency; When the real-time conductivity of the condensed water at the first detection point 6 is Less than the standard conductivity When the ammonia adding pump is increased to a fixed frequency.

[0038] In this embodiment, according to the real-time conductivity and standard conductivity The ammonia adding pump is adjusted based on the comparison results. With a faster refresh frequency, the pH value can be adjusted to the standard conductivity in the first time when the conductivity of the condensate water is abnormal, thereby improving the stability of the PH control of the boiler feed water.

[0039] In one implementation, the fixed frequency is 1-3 Hz.

[0040] In a preferred implementation, the fixed frequency is 2 Hz.

[0041] In this embodiment, the ammonia pump is adjusted to a fixed frequency each time, which not only reduces the calculation burden of the automatic control cabinet 12, but also avoids the problem of a short service life of the ammonia pump caused by a large frequency adjustment range in the prior art. When the fixed frequency is 2 Hz, the fluctuation range of the conductivity is within 0.6 μS / cm, and the pH fluctuation is within 0.05, and the adjustment range is reasonable.

[0042] In one embodiment, the method for suppressing fluctuations in the pH value of boiler feed water includes: The condensate produced by the condenser 1 is treated by the fine treatment device 3 and then mixed with the ammonia solution of the ammonia adding unit for pH adjustment treatment, and the obtained condensate is sent to the deaerator 4 for deoxygenation treatment to obtain boiler feed water; The pH adjustment process comprises: When the real-time conductivity of the condensed water at the first detection point 6 is In the standard conductivity When the speed is above 200Hz, the ammonia pump is reduced by 2Hz; When the real-time conductivity of the condensed water at the first detection point 6 is Less than the standard conductivity When the ammonia pump is increased by 2 Hz; Wherein, the first detection point 6 is arranged on the inlet pipeline of the deaerator, and the ratio of the pipeline length between the fine treatment ammonia addition point 5 and the inlet of the deaerator 4 to the pipeline length between the fine treatment ammonia addition point 5 and the first detection point 6 is (3.5-5):1; The standard conductivity It is 5.8~6.5μS / cm.

[0043] In one embodiment, the ammonia addition unit further includes a water ammonia addition pump and a water ammonia addition main path; the outlet of the ammonia solution tank 8 is connected to the inlet of the water ammonia addition pump; the outlet of the water ammonia addition pump is connected to the outlet pipeline of the deaerator 4 through the water ammonia addition main path; the connection point between the water ammonia addition main path and the outlet pipeline of the deaerator 4 is the water ammonia addition point 15; The pH adjustment process further comprises: The ammonia addition control device is configured to detect the real-time conductivity of the boiler feed water at the second detection point 7. With standard conductivity The comparison result is used to adjust the operating state of the water supply ammonia addition pump; wherein the second detection point 7 is arranged on the deaerator outlet pipeline and the second detection point 7 is arranged downstream of the water supply ammonia addition point 15.

[0044] In one embodiment, the ammonia addition control device also includes a second conductivity meter 14; the second conductivity meter 14 is arranged at the second detection point 7, and is used to detect the conductivity of the boiler feed water at the second detection point 7; the automatic control cabinet 12 is electrically connected to the second conductivity meter 14 and the feed water ammonia addition pump, and is used to receive the conductivity signal of the second conductivity meter 14, and adjust the operating state of the feed water ammonia addition pump according to the conductivity signal.

[0045] In one embodiment, when the real-time conductivity of the boiler feed water at the second detection point 7 is In the standard conductivity When the above conditions are met, the water supply ammonia pump is in a shutdown state; When the real-time conductivity of the boiler feed water at the second detection point 7 is Less than the standard conductivity Or when both the first ammonia dosing pump 9 and the second ammonia dosing pump 10 fail, the water supply ammonia dosing pump is turned on and the fixed frequency is increased once.

[0046] In this embodiment, the above-mentioned device setting and operation method are adopted, so that the feed water ammonia pump can be in a shutdown state during most of the operation time of the ammonia dosing unit. The feed water ammonia dosing pump is only started for fine-tuning when the conductivity of the boiler feed water is not within the standard conductivity range or the unit is started and stopped or the ammonia dosing unit of the condensate system fails.

[0047] In one embodiment, the ammonia adding pump comprises a first water supply ammonia adding pump 16 and a second water supply ammonia adding pump 17 arranged in parallel; When the first water supply and ammonia pump 16 fails, the second water supply and ammonia pump 17 is switched so that the ammonia solution in the ammonia solution tank 8 enters the water supply and ammonia main path under the action of the second water supply and ammonia pump 17; When the second water supply and ammonia addition pump 17 fails, the first water supply and ammonia addition pump 16 is switched so that the ammonia solution in the ammonia solution tank 8 enters the water supply and ammonia addition main path under the action of the first water supply and ammonia addition pump 16 .

[0048] In one embodiment, the ammonia solution tank 8 includes two ammonia solution storage devices arranged in parallel, and the first ammonia adding pump 9, the second ammonia adding pump 10, the first water supply ammonia adding pump 16 and the second water supply ammonia adding pump 17 share two ammonia solution storage devices.

[0049] By adopting the method disclosed in the present invention, the first detection point 6 is set close to the fine treatment ammonia addition point 5, which can reduce the delay in detecting conductivity and make the detected conductivity more accurate, thereby improving the accuracy of ammonia addition by the ammonia addition unit, so as to improve the accuracy of boiler feed water pH control. In addition, the frequency of the ammonia addition pump is adjusted according to the comparison result between the real-time conductivity of the condensate water at the first detection point 6 and the standard conductivity, so that the real-time conductivity of the condensate water fluctuates within a narrow range, which can improve the stability of boiler feed water pH control. In addition, by adopting the method disclosed in the present invention, pH adjustment can be completed at the fine treatment ammonia addition point, which can reduce the frequency of use of associated equipment and pipelines at the feed water ammonia addition point and reduce the complexity of pH adjustment.

[0050] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0051] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0052] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for suppressing pH fluctuations in boiler feed water, characterized in that: The method includes: The condensate produced by the condenser is treated by a fine treatment device and then mixed with an ammonia solution of an ammonia adding unit for pH adjustment treatment, and the obtained condensate is sent to a deaerator for deoxygenation treatment to obtain boiler feed water; The ammonia addition unit comprises an ammonia solution tank, an ammonia addition pump, an ammonia addition control device and an ammonia addition main line; the inlet of the ammonia solution tank is used to communicate with an ammonia solution source, and the outlet of the ammonia solution tank is communicated with the inlet of the ammonia addition pump; the outlet of the ammonia addition pump is communicated with the inlet pipeline of the deaerator through the ammonia addition main line; the connection point between the ammonia addition main line and the inlet pipeline of the deaerator is a fine treatment ammonia addition point; The pH adjustment process comprises: The ammonia addition control device is configured to control the condensate water at the first detection point according to the real-time conductivity of the condensate water. With standard conductivity The comparison result adjusts the frequency of the ammonia adding pump; Wherein, the first detection point is arranged on the inlet pipeline of the deaerator, and the ratio of the pipeline length between the fine treatment ammonia addition point and the inlet of the deaerator to the pipeline length between the fine treatment ammonia addition point and the first detection point is (3.5-5):1; The standard conductivity It is 5.8~6.5μS / cm.

2. The method according to claim 1, characterized in that The ratio of the pipeline length between the fine treatment ammonia addition point and the inlet of the deaerator to the pipeline length between the fine treatment ammonia addition point and the first detection point is (4~4.5):

1.

3. The method according to claim 1, characterized in that: The standard conductivity of the boiler feed water It is 6.0~6.4μS / cm.

4. The method according to claim 1, characterized in that: The ammonia addition control device includes an automatic control cabinet and a first conductivity meter; The first conductivity meter is arranged at the first detection point, and is used to detect the conductivity of the condensed water at the first detection point; The automatic control cabinet is electrically connected to the first conductivity meter and the ammonia adding pump, and is used to receive the conductivity signal of the first conductivity meter and adjust the frequency of the ammonia adding pump according to the conductivity signal.

5. The method according to claim 4, characterized in that The adjustment frequency of the automatic control cabinet is 3 to 6 minutes per time.

6. The method according to claim 4, characterized in that The adjustment frequency of the automatic control cabinet is 5 minutes per time.

7. The method according to claim 1, characterized in that The pH adjustment process further comprises: When the real-time conductivity of the condensed water at the first detection point is In the standard conductivity When the above, the ammonia pump is reduced by a fixed frequency; When the real-time conductivity of the condensed water at the first detection point is Less than the standard conductivity When the ammonia adding pump is increased to a fixed frequency.

8. The method according to claim 7, characterized in that The fixed frequency is 1~3Hz.

9. The method according to claim 7, characterized in that: The fixed frequency is 2 Hz.

10. The method according to claim 5, characterized in that The ammonia adding pump comprises a first ammonia adding pump and a second ammonia adding pump arranged in parallel; When the first ammonia adding pump fails, the second ammonia adding pump is switched so that the ammonia solution in the ammonia solution tank enters the ammonia adding main path under the action of the second ammonia adding pump; When the second ammonia adding pump fails, the first ammonia adding pump is switched so that the ammonia solution in the ammonia solution tank enters the ammonia adding main path under the action of the first ammonia adding pump.

Images