Comprehensive evaluation method and system for shutdown maintenance of thermal equipment

Abstract

The invention discloses a thermal equipment shutdown maintenance comprehensive evaluation method and system, and solves the problems that the thermal equipment shutdown maintenance evaluation method is single, the cost is low and the like through collaborative analysis of five parameters, namely boiler water discharge temperature / pressure, discharge air humidity, coupon corrosion condition, unit start-up flushing water quantity and turbidity, and an evaluation model is constructed. And the shutdown protection effect and the shutdown corrosion of the thermal equipment cannot be effectively evaluated. The method starts from furnace shutdown protection water discharging and drying operation, and comprises the steps of monitoring in the shutdown period, flushing in the starting process and evaluation of the whole process from shutdown to starting. By evaluating the shutdown maintenance effect of the thermal equipment, abnormal conditions are found in time, shutdown maintenance measures are improved, the leakage risk caused by shutdown corrosion is reduced, the flushing water amount is reduced, and the operation safety and reliability of the thermal equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of chemical corrosion protection and evaluation technology in thermal power plants, specifically to a comprehensive evaluation method for the shutdown and maintenance of thermal equipment. Background Technology

[0002] Thermal power plant equipment such as boiler economizers, water-cooled walls, and steam turbines are prone to oxygen corrosion during shutdown due to humid environments, leading to equipment performance degradation. Economizers and water-cooled walls experience intensified under-scale corrosion, and the accumulation of deposits in boiler tubes increases the risk of boiler corrosion leaks. Steam turbine blades, under the influence of corrosive ions, exacerbate the formation of corrosion cracks. All of these factors pose safety hazards to critical power plant equipment and risks to the stable operation of the unit.

[0003] DL / T 956-2017, "Guidelines for Rust Prevention of Thermal Equipment in Thermal Power Plants During Shutdown (Standby)," specifies techniques for dry and wet maintenance of thermal equipment. However, in practice, improper operation or inaccurate control parameters can lead to unsatisfactory maintenance results, prominent scaling and corrosion problems, and slow attainment of acceptable water quality during unit startup flushing. Furthermore, the lack of effective evaluation methods to guide the shutdown maintenance of thermal equipment creates significant challenges.

[0004] Currently, the methods for evaluating the shutdown and maintenance of thermal equipment are limited. For example, weighted calculations are performed after testing the unit's start-up flushing water volume and iron content. However, this requires manual testing, is time-consuming, cannot provide real-time water quality information, and is inconvenient. Some have proposed using online particulate matter monitoring devices to monitor the quality of the water used for start-up flushing, but the representativeness of particulate matter is insufficient, and this method has not been widely adopted by power plants. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a comprehensive evaluation method and system for the shutdown and maintenance of thermal equipment. It solves the problems of limited and insufficiently representative evaluation methods for thermal equipment shutdown and maintenance. The method employs a comprehensive evaluation of multiple factors, including boiler drain water temperature / pressure, exhaust air humidity, fin corrosion rate, unit start-up flushing water volume, and turbidity. This results in more accurate and effective evaluation results, comprehensively and accurately reflecting the effectiveness of thermal equipment shutdown and maintenance, providing guidance for thermal equipment shutdown and maintenance, and reducing the risk of corrosion during shutdown.

[0006] This invention is achieved through the following technical solution: A comprehensive evaluation method for the shutdown and maintenance of thermal equipment, including, Before the unit of the thermal power equipment is shut down, the boiler discharge water temperature and pressure evaluation index TP is obtained based on the boiler discharge water pressure and temperature. After the boiler is drained, the thermal equipment is dried and the humidity value is recorded to obtain the exhaust air humidity evaluation index HU. Before starting the thermal equipment unit, the corrosion amount of the corrosion plates installed in the water-cooled wall is detected, the corrosion rate of the plates is obtained, and the corrosion status evaluation index CO is obtained based on the corrosion rate of the plates. During the unit flushing process of thermal equipment, the unit start-up flushing water volume and the unit start-up flushing turbidity are obtained, and the unit start-up flushing water volume evaluation index WQ and the unit start-up flushing turbidity evaluation index TU are obtained. Based on the evaluation index TP for boiler discharge water temperature and pressure, the evaluation index HU for discharged air humidity, the evaluation index CO for corrosion status, the evaluation index WQ for unit start-up flushing water volume, and the evaluation index TU for unit start-up flushing turbidity, a comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, thereby outputting the evaluation level of the shutdown and maintenance effect of thermal equipment.

[0007] Preferably, the boiler discharge water temperature and pressure evaluation index TP is as follows: When both the discharge pressure a and the temperature b are above the median of their respective preset value ranges, the boiler discharge temperature and pressure evaluation index TP is 1.0. When both the discharge pressure a and temperature b are within the preset range but below the median, the boiler discharge temperature and pressure evaluation index TP is 0.9. When either the discharge pressure a or the temperature b is below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.8. When both the discharge pressure a and temperature b are below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.7.

[0008] Preferably, the exhaust air humidity evaluation index HU is obtained as follows: After the boiler is drained, the thermal equipment is dried by the air drying system. The humidity value c of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value d of the second online hygrometer installed at the turbine exhaust port are recorded. Before the unit of thermal equipment is started, the humidity value f of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value g of the second online hygrometer installed at the turbine exhaust port are recorded again. The average humidity is calculated based on humidity values ​​c, d, f, and g. The exhaust air humidity evaluation index HU is obtained based on this average humidity value. The exhaust air humidity evaluation index HU is specifically as follows: When the average humidity is less than 50%, the air humidity evaluation index HU is 1.0; When the average humidity is greater than or equal to 50% and less than 60%, the air humidity evaluation index HU is 0.9; When the average humidity is greater than or equal to 60% and less than 65%, the air humidity evaluation index HU is 0.8; When the average humidity is greater than or equal to 65%, the air humidity evaluation index HU is 0.7.

[0009] Preferably, the corrosion status evaluation index CO is obtained as follows: If the downtime of the thermal equipment exceeds a predetermined threshold, the corrosion plates installed in the water-cooled wall are inspected, the corrosion amount of the corrosion plates is detected, the corrosion rate e of the plates is calculated, and the corrosion status evaluation index CO is obtained. The corrosion status evaluation index CO is specifically: When the downtime is less than 30 days, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is lower than the standard control value, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is within the standard control range, the corrosion status evaluation index CO is 0.9. When the downtime exceeds 30 days and the corrosion rate e of the coating exceeds the standard control value, the corrosion status evaluation index is 0.8.

[0010] Preferably, the evaluation index WQ for unit start-up flushing water volume and the evaluation index TU for unit start-up flushing turbidity are obtained, specifically as follows: During the start-up flushing process of the thermal equipment, the maximum values ​​of the online turbidity meter h1, h2, h3, and h4 of the condensate pump outlet, deaerator outlet, separator drainage during cold flushing, and separator drainage during hot flushing are detected respectively, and the qualified flushing water volume q1, q2, q3, and q4 for each stage are calculated accordingly. The evaluation index WQ of the unit start-up flushing water volume is obtained by comparing the sum of qualified flushing water volumes q1, q2, q3, and q4 with the baseline water volume q. The turbidity evaluation index TU for unit start-up flushing is obtained by comparing the average values ​​of the maximum values ​​h1, h2, h3, and h4 of the online turbidity meter with the reference turbidity h.

[0011] Preferably, the evaluation index WQ for unit start-up flushing water volume is as follows: When the total qualified flushing water volume of q1+q2+q3+q4 is less than 0.8 times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 1.0; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [0.8-1.0) times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.9; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [1.0-1.2) times the reference water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.8; When the total qualified flushing water volume of q1+q2+q3+q4 is greater than or equal to 1.2q times the benchmark water volume q, the unit start-up flushing water volume evaluation index WQ is 0.7.

[0012] Preferably, the turbidity evaluation index TU for unit start-up flushing is as follows: When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is less than 0.8 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 1.0. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is between 0.8 and 1.0 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.9. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is within [1.0-1.2] times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.8. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is greater than or equal to 1.2 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.7.

[0013] Preferably, a comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, the specific expression of which is:

[0014] Where I is the comprehensive maintenance effect evaluation value, and k1, k2, k3, k4, and k5 are all weighting coefficients. ; The comprehensive maintenance effect evaluation value I is compared with the preset threshold range, and the evaluation level of the maintenance effect is output.

[0015] The preferred evaluation level for maintenance effect is as follows: when At that time, the maintenance effect was rated as excellent; when At that time, the maintenance effect was rated as average; when At that time, the maintenance effect was rated as poor.

[0016] A system for implementing a comprehensive evaluation method for the shutdown and maintenance of the aforementioned thermal equipment, comprising: The first online hygrometer is installed at the exhaust port of the water-cooled wall of the thermal equipment; A second online humidity meter installed at the turbine exhaust port of a thermal power plant; Multichannel online turbidity meters are installed at the condensate pump outlet, deaerator outlet, and economizer drain pipeline of thermal equipment. Corrosion-resistant plates installed inside the water-cooled walls of thermal equipment; The data acquisition and processing unit is used to acquire the readings of the hygrometer and turbidimeter, and to receive the inspection results of the corrosion pads; The index calculation unit is configured to perform the boiler discharge water temperature and pressure evaluation index TP, the exhaust air humidity evaluation index HU, the corrosion status evaluation index CO, the unit start-up flushing water volume evaluation index WQ, and the unit start-up flushing turbidity evaluation index TU, as well as the calculation steps and comprehensive evaluation system steps. The output unit is used to output the evaluation level of the maintenance effect of the thermal equipment during shutdown.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a comprehensive evaluation method and system for the shutdown and maintenance of thermal equipment. By integrating evaluation indicators such as boiler drain water temperature and pressure (TP), exhaust air humidity (HU), corrosion status (CO), unit start-up flushing water volume (WQ), and unit start-up flushing turbidity (TU), a multi-factor weighted fusion comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed. This system can comprehensively, accurately, and quantitatively reflect the maintenance status of the thermal system during shutdown. This method not only achieves an objective and quantitative assessment of the entire process from drying effect and corrosion degree to flushing water quality and quantity, overcoming the limitations of traditional single-indicator evaluation, but also requires no modification to the main system, only the addition of a few online instruments. The modification is simple and highly automated, solving the problems of single and insufficient representativeness in the evaluation of thermal equipment shutdown and maintenance. By using a multi-factor comprehensive evaluation of boiler drain water temperature / pressure, exhaust air humidity, fin corrosion rate, unit start-up flushing water volume, and turbidity, the evaluation results are more accurate and effective, comprehensively and accurately reflecting the effect of thermal equipment shutdown and maintenance, providing guidance for thermal equipment shutdown and maintenance, and reducing the risk of corrosion during thermal equipment shutdown.

[0018] Furthermore, the boiler drain water temperature and pressure evaluation index TP determines the cleanliness of the drain water. Higher pressure corresponds to a larger discharge volume, while temperature corresponds to the degree of drying of the heating surfaces. The maximum drain water temperature and pressure must not exceed the boiler's allowable values. Draining water from a hot boiler is an important operation for the shutdown and maintenance of thermal equipment. In actual operation, the control of drain water temperature and pressure varies, resulting in different shutdown and maintenance effects.

[0019] Furthermore, the exhaust air humidity index (HU) characterizes the humidity level of the air and can reflect the dehumidification effect of the hot furnace water discharge to a certain extent, while temperature and pressure can only reflect drainage efficiency. The lower the air humidity, the less corrosive it is to thermal equipment.

[0020] Furthermore, the corrosion status evaluation index CO characterizes the corrosion rate during equipment downtime. The maintenance effect of downtime for thermal equipment is related to the corrosion rate. Long downtime and increased internal humidity will lead to an increased corrosion rate in the later stages.

[0021] Furthermore, the evaluation index WQ for unit start-up flushing water volume is the total water consumption from the start of unit start-up flushing until the flushing water quality meets the standards. If the thermal equipment is properly maintained during shutdown, there will be fewer corrosion products, the water quality will meet the standards quickly during flushing, and the total water consumption will be small.

[0022] Furthermore, the turbidity evaluation index TU for unit start-up flushing is the average maximum turbidity at each stage from the start of unit start-up flushing to when the flushing water quality meets the standards. If the thermal equipment is shut down and well maintained, there will be fewer corrosion products and the turbidity of the flushing water at each stage will be low.

[0023] Furthermore, this method is applicable to the downtime maintenance evaluation of all thermal equipment in power plants.

[0024] Furthermore, without altering the existing system equipment, online humidity meters and online turbidity meters are added, resulting in minimal modification work and a high degree of automation.

[0025] Furthermore, the implementation process is simple, the application effect is good, and it is easy to implement. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a comprehensive evaluation system for the shutdown and maintenance of thermal equipment; In the diagram: Boiler 1, Economizer 2, Water-cooled wall 3, Superheater 4, Reheater 5, Steam turbine 6, Condenser 7, Condensate pump 8, Low-pressure heater 9, Deaerator 10, Feed water pump 11, High-pressure heater 12, Air drying system 13, Corrosion fins 14, First online hygrometer 15, Second online hygrometer 16, Online turbidity meter 17. Detailed Implementation

[0028] 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, not all, of the embodiments of the present invention. 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. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] A comprehensive evaluation method for the shutdown and maintenance of thermal equipment, such as Figure 1 As shown, including, Before the unit of the thermal equipment is shut down, the boiler is controlled to discharge water at the discharge pressure and corresponding temperature. Based on the discharge pressure and temperature, the boiler discharge temperature and pressure evaluation index TP is obtained. The evaluation index TP for boiler drain water temperature and pressure is obtained as follows: Before shutting down the thermal equipment unit, increase the amount of ammonia added to the outlet of the condensate pump to increase the pH value of the feedwater at the economizer inlet. When the boiler needs to drain water, drain all the water stored in the boiler when the boiler drain pressure is detected to be a and the corresponding inlet water temperature is b. The boiler discharge temperature and pressure evaluation index TP is as follows: When both the discharge pressure a and the temperature b are above the median of their respective preset value ranges, the boiler discharge temperature and pressure evaluation index TP is 1.0. When both the discharge pressure a and temperature b are within the preset range but below the median, the boiler discharge temperature and pressure evaluation index TP is 0.9. When either the discharge pressure a or the temperature b is below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.8. When both the discharge pressure a and temperature b are below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.7. The boiler is either a once-through boiler or a drum boiler. When it is a once-through boiler, a separator is used to detect the drain pressure 'a'. When it is a drum boiler, a steam drum is used to detect the drain pressure 'a'.

[0030] After the boiler is drained, the thermal equipment is dried and the humidity value is recorded to obtain the exhaust air humidity evaluation index HU. The exhaust air humidity evaluation index HU is obtained as follows: After the boiler is drained, the thermal equipment is dried by the air drying system. The humidity value c of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value d of the second online hygrometer installed at the turbine exhaust port are recorded. Before the unit of thermal equipment is started, the humidity value f of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value g of the second online hygrometer installed at the turbine exhaust port are recorded again. The average humidity is calculated based on humidity values ​​c, d, f, and g. The exhaust air humidity evaluation index HU is obtained based on this average humidity value. The exhaust air humidity evaluation index HU is specifically as follows: When the average humidity is less than 50%, the air humidity evaluation index HU is 1.0; When the average humidity is greater than or equal to 50% and less than 60%, the air humidity evaluation index HU is 0.9; When the average humidity is greater than or equal to 60% and less than 65%, the air humidity evaluation index HU is 0.8; When the average humidity is greater than or equal to 65%, the air humidity evaluation index HU is 0.7.

[0031] Before starting the thermal equipment unit, the corrosion amount of the corrosion plates installed in the water-cooled wall is detected, the corrosion rate of the plates is obtained, and the corrosion status evaluation index CO is obtained based on the corrosion rate of the plates. The corrosion status evaluation index CO is obtained as follows: If the downtime of the thermal equipment exceeds a predetermined threshold, the corrosion plates installed in the water-cooled wall are inspected, the corrosion amount of the corrosion plates is detected, the corrosion rate e of the plates is calculated, and the corrosion status evaluation index CO is obtained. The corrosion status evaluation index CO is specifically: When the downtime is less than 30 days, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is lower than the standard control value, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is within the standard control range, the corrosion status evaluation index CO is 0.9. When the downtime exceeds 30 days and the corrosion rate e of the coating exceeds the standard control value, the corrosion status evaluation index is 0.8.

[0032] During the unit flushing process of thermal equipment, the unit start-up flushing water volume and the unit start-up flushing turbidity are obtained, and the unit start-up flushing water volume evaluation index WQ and the unit start-up flushing turbidity evaluation index TU are obtained. The evaluation indexes WQ (volume of start-up flushing water) and TU (turbidity of start-up flushing water) were obtained, specifically as follows: During the start-up flushing process of the thermal equipment, the maximum values ​​of the online turbidity meter h1, h2, h3, and h4 of the condensate pump outlet, deaerator outlet, separator drainage during cold flushing, and separator drainage during hot flushing are detected respectively, and the qualified flushing water volume q1, q2, q3, and q4 for each stage are calculated accordingly. The evaluation index WQ of the unit start-up flushing water volume is obtained by comparing the sum of qualified flushing water volumes q1, q2, q3, and q4 with the baseline water volume q. The turbidity evaluation index TU for unit start-up flushing is obtained by comparing the average values ​​of the maximum values ​​h1, h2, h3, and h4 of the online turbidity meter with the reference turbidity h.

[0033] The evaluation index WQ for unit start-up flushing water volume is as follows: When the total qualified flushing water volume of q1+q2+q3+q4 is less than 0.8 times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 1.0; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [0.8-1.0) times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.9; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [1.0-1.2) times the reference water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.8; When the total qualified flushing water volume of q1+q2+q3+q4 is greater than or equal to 1.2q times the benchmark water volume q, the unit start-up flushing water volume evaluation index WQ is 0.7.

[0034] The turbidity evaluation index TU for unit start-up flushing is as follows: When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is less than 0.8 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 1.0. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is between 0.8 and 1.0 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.9. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is within [1.0-1.2] times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.8. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is greater than or equal to 1.2 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.7.

[0035] Based on the evaluation index TP for boiler discharge water temperature and pressure, the evaluation index HU for discharged air humidity, the evaluation index CO for corrosion status, the evaluation index WQ for unit start-up flushing water volume, and the evaluation index TU for unit start-up flushing turbidity, a comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, thereby outputting the evaluation level of the shutdown and maintenance effect of thermal equipment.

[0036] A comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, with the specific expression as follows:

[0037] Where I represents the comprehensive maintenance effect evaluation value, and k1, k2, k3, k4, and k5 are the weighting coefficients for the boiler drain water temperature / pressure evaluation index, the exhaust air humidity evaluation index, the corrosion status evaluation index, the unit start-up flushing water volume, and the turbidity evaluation index, respectively. ; The comprehensive maintenance effect evaluation value I is compared with the preset threshold range, and the evaluation level of the maintenance effect is output.

[0038] The evaluation levels for maintenance effectiveness are as follows: when At that time, the maintenance effect was rated as excellent; when At that time, the maintenance effect was rated as average; when At that time, the maintenance effect was rated as poor.

[0039] A comprehensive evaluation system for the shutdown and maintenance of thermal equipment, such as Figure 1 As shown, it includes: Boiler 1, steam turbine 6, condenser 7, condensate pump 8, low-pressure heater 9, deaerator 10, feedwater pump 11, high-pressure heater 12, and air drying system 13; The boiler 1 includes an economizer 2, a water-cooled wall 3, a superheater 4, and a reheater 5.

[0040] The water-cooled wall 3 is equipped with corrosion-resistant plates 14, and the exhaust port of the water-cooled wall 3 is equipped with a first online hygrometer 15. The exhaust port of the steam turbine 6 is equipped with a second online hygrometer 16. The outlet of the condensate pump 8, the outlet of the deaerator 10, and the drainage of the economizer 2 are equipped with multi-channel online turbidity meters 17.

[0041] The data acquisition and processing unit is used to acquire the readings of the hygrometer and turbidimeter, and to receive the inspection results of the corrosion pads; The index calculation unit is configured to perform the boiler discharge water temperature and pressure evaluation index TP, the exhaust air humidity evaluation index HU, the corrosion status evaluation index CO, the unit start-up flushing water volume evaluation index WQ, and the unit start-up flushing turbidity evaluation index TU, as well as the calculation steps and comprehensive evaluation system steps. The output unit is used to output the evaluation level of the maintenance effect of the thermal equipment during shutdown.

[0042] This method constructs an evaluation model through the synergistic analysis of five parameters: boiler drain water temperature / pressure, exhaust air humidity, fin corrosion rate, unit start-up flushing water volume, and turbidity. This addresses the problem of simplistic evaluation methods for thermal equipment shutdown maintenance, which are ineffective in assessing the effectiveness of shutdown protection and corrosion during shutdown. The method begins with the boiler shutdown protection draining and drying operation, encompassing monitoring during shutdown and flushing during startup, providing a comprehensive evaluation throughout the entire process from shutdown to startup. By evaluating the effectiveness of thermal equipment shutdown maintenance, abnormalities can be identified promptly, shutdown maintenance measures can be improved, the risk of leakage caused by shutdown corrosion can be reduced, flushing water volume can be decreased, and the operational safety and reliability of thermal equipment can be improved.

[0043] The comprehensive evaluation system for the shutdown and maintenance of thermal equipment in this invention incorporates relevant factors: boiler drain water temperature / pressure, exhaust air humidity, fin corrosion rate, unit start-up flushing water volume and turbidity, and assigns certain weights according to their importance.

[0044] The boiler drain water temperature and pressure evaluation index TP determines the cleanliness of the drain water. Higher pressure corresponds to a larger discharge volume, while temperature corresponds to the degree of drying of the heating surfaces. The maximum drain water temperature and pressure must not exceed the boiler's allowable values. Draining water from a hot boiler is an important operation for the shutdown and maintenance of thermal equipment. In actual operation, the control of drain water temperature and pressure varies, resulting in different shutdown and maintenance effects.

[0045] The exhaust air humidity index (HU) characterizes the humidity level of the air and can reflect the dehumidification effect of hot furnace drainage to a certain extent. However, temperature and pressure only reflect drainage efficiency. The lower the air humidity, the less corrosive it is to thermal equipment.

[0046] The corrosion rate (CO) index characterizes the corrosion rate during equipment downtime. The effectiveness of maintenance during downtime of thermal equipment is related to the corrosion rate. Long downtime and increased internal humidity will lead to a higher corrosion rate in the later stages.

[0047] The evaluation index WQ for unit start-up flushing water volume is the total water consumption from the start of unit start-up flushing until the flushing water quality meets the standards. If the thermal equipment is shut down and well maintained, there will be fewer corrosion products, the water quality will meet the standards quickly during flushing, and the total water consumption will be small.

[0048] The turbidity evaluation index TU for unit start-up flushing is the average maximum turbidity at each stage from the start of unit start-up flushing to when the flushing water quality meets the standards. If the thermal equipment is shut down and well maintained, there will be fewer corrosion products and the turbidity of the flushing water at each stage will be low.

[0049] Example 1 A comprehensive evaluation method for the shutdown and maintenance of thermal equipment, including, Before the unit is shut down, bypass the condensate demineralization equipment, increase the ammonia addition at the outlet of condensate pump 8, and increase the pH of the feedwater at the inlet of economizer 2. When the boiler needs to drain water, when the pressure in the steam drum or separator drops to aMPa and the corresponding inlet water temperature drops to b℃, quickly drain all the water stored in the boiler.

[0050] Depending on the duration of the shutdown, the air drying system 13 is activated to dry the economizer 2, water-cooled wall 3, superheater 4, reheater 5, and steam turbine 6.

[0051] After the boiler is drained and the air is dried, record the value c of the first online hygrometer 15 and the value d of the second online hygrometer 16. Install corrosion-resistant plates 14 inside the water-cooled wall 3.

[0052] Before starting the unit, inspect the corrosion-resistant pad 14, measure the amount of corrosion, and calculate the corrosion rate e. Record the values ​​f of the first online hygrometer 15 and g of the second online hygrometer 16 again.

[0053] When the unit starts up, check the maximum value h1 of the online turbidity meter 17 at the outlet of condensate pump 8, and calculate the qualified water consumption q1 based on the flushing time and flow rate; The maximum value h2 of the online turbidity meter 17 at the outlet of deaerator 10 is detected, and the qualified water consumption q2 is calculated based on the flushing time and flow rate. During cold flushing, the maximum value h3 of the online turbidity meter 17 in the separator drainage is detected, and the qualified water consumption q3 is calculated based on the flushing time and flow rate. During hot flushing, the maximum value h4 of the online turbidity meter 17 in the separator drainage is detected, and the qualified water consumption q4 is calculated based on the flushing time and flow rate.

[0054] The study analyzed the importance of boiler discharge water temperature / pressure, exhaust air humidity, corrosion status evaluation indicators, unit start-up flushing water volume and turbidity in reflecting the shutdown protection work, and assigned them weights of 0.2, 0.25, 0.3, 0.15 and 0.1, respectively.

[0055] Establish a comprehensive evaluation system for the shutdown and maintenance of thermal equipment:

[0056] Excellent maintenance effect; The maintenance effect is mediocre and needs further improvement; The maintenance effect is poor and needs to be improved immediately to prevent corrosion when the product is no longer in use.

[0057] 1) Different discharge pressure and temperature ranges are specified for once-through boilers and drum boilers. The higher the discharge pressure a and temperature b, the better the drainage effect and the more beneficial it is to the drying of the boiler.

[0058] If the water pressure a and temperature b are above the median of the preset specified range, it indicates good effect, and TP is set to 1.0; If the discharge pressure a and temperature b are below the median and within the specified value, it indicates a good effect; TP is taken as 0.9. If the individual water pressure 'a' and temperature 'b' are below the preset values, it indicates that the effect is average, and TP should be set to 0.8. If the water pressure a and temperature b are below the preset values, it indicates poor performance; therefore, TP should be set to 0.7.

[0059] 2) According to the research results, the equipment has a better anti-corrosion effect when the humidity is below 60%.

[0060] A humidity level of less than 50% indicates good performance; HU should be set to 1.0. A humidity level of 50% to 60% indicates good results, with a HU value of 0.9. A humidity level of 60%~65% indicates that the effect is average, and the HU value should be 0.8. A humidity level greater than 65% indicates poor performance; therefore, HU should be set to 0.7.

[0061] The humidity is taken as the average value of c, d, f, and g.

[0062] 3) If the downtime is less than 30 days, corrosion plates do not need to be hung, and CO should be 1. If the downtime exceeds 30 days, the corrosion rate is tested using a suspended corrosion plate. Almost no corrosion is observed, and CO is set to 1. The corrosion rate is within the standard control value, the corrosion rate is low, and CO is taken as 0.9; The corrosion rate exceeds the standard control value, indicating a high corrosion rate. The CO value is set at 0.8.

[0063] 4) Set the baseline flushing water volume q based on the unit's start-up flushing status; If the flushing water volume is less than 0.8q, it indicates that the water consumption is low, so WQ is taken as 1.0; A flushing water volume between 0.8q and q indicates low water consumption; therefore, WQ is set to 0.9. The flushing water volume is between q and 1.2q, indicating a large water consumption. WQ is taken as 0.8. A flushing water volume greater than 1.2q indicates a high water consumption; therefore, WQ should be set to 0.7.

[0064] The flushing water volume is the sum of q1, q2, q3, and q4.

[0065] 5) Set the baseline flushing water turbidity h according to the unit's start-up flushing status; If the turbidity of the flushing water is less than 0.8 h, it indicates low turbidity; TU should be taken as 1.0. The turbidity of the flushing water is between 0.8h and 0.9h, indicating low turbidity. TU is taken as 0.9. The turbidity of the flushing water is between h and 1.2h, indicating that the turbidity is relatively high. The TU value is taken as 0.8. If the turbidity of the rinsing water is greater than 1.2h, it indicates high turbidity; TU should be taken as 0.7.

[0066] The turbidity of the rinsing water is taken as the average value of h1, h2, h3, and h4.

[0067] In one preferred embodiment, when a once-through boiler is shut down, the drain pressure a = 1.6 MPa, the drain temperature b = 220℃, and TP is taken as 0.9; after the boiler draining is completed and the air is dried, c = 49%, d = 47%, f = 53%, g = 50%, and HU is taken as 1; the shutdown time is less than 30 days, and CO is taken as 1; the cold flushing baseline flushing water consumption is 600 m³ / h. 3 The actual total water consumption was 520 m³. 3 WQ is set to 0.9; the turbidity of the cold flushing reference flushing water is 10 NTU, the average turbidity is 8.3 NTU, and TU is set to 0.9.

[0068]

[0069]

[0070]

[0071]

[0072] It has excellent maintenance effects.

[0073] This invention provides a comprehensive evaluation method for the shutdown and maintenance of thermal power equipment. Employing a multi-factor comprehensive evaluation, the results are more accurate and effective, comprehensively and accurately reflecting the effectiveness of the shutdown and maintenance of thermal power equipment. This provides guidance for the shutdown and maintenance of thermal power equipment and reduces the risk of corrosion during shutdown. Consequently, it improves the reliability of the unit and ensures its safe and stable operation.

[0074] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0075] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0076] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A comprehensive evaluation method for the shutdown and maintenance of thermal equipment, characterized in that, include, Before the unit of the thermal power equipment is shut down, the boiler discharge water temperature and pressure evaluation index TP is obtained based on the boiler discharge water pressure and temperature. After the boiler is drained, the thermal equipment is dried and the humidity value is recorded to obtain the exhaust air humidity evaluation index HU. Before starting the thermal equipment unit, the corrosion amount of the corrosion plates installed in the water-cooled wall is detected, the corrosion rate of the plates is obtained, and the corrosion status evaluation index CO is obtained based on the corrosion rate of the plates. During the unit flushing process of thermal equipment, the unit start-up flushing water volume and the unit start-up flushing turbidity are obtained, and the unit start-up flushing water volume evaluation index WQ and the unit start-up flushing turbidity evaluation index TU are obtained. Based on the evaluation index TP for boiler discharge water temperature and pressure, the evaluation index HU for discharged air humidity, the evaluation index CO for corrosion status, the evaluation index WQ for unit start-up flushing water volume, and the evaluation index TU for unit start-up flushing turbidity, a comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, thereby outputting the evaluation level of the shutdown and maintenance effect of thermal equipment.

2. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 1, characterized in that, The boiler discharge temperature and pressure evaluation index TP is as follows: When both the discharge pressure a and the temperature b are above the median of their respective preset value ranges, the boiler discharge temperature and pressure evaluation index TP is 1.

0. When both the discharge pressure a and temperature b are within the preset range but below the median, the boiler discharge temperature and pressure evaluation index TP is 0.

9. When either the discharge pressure a or the temperature b is below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.

8. When both the discharge pressure a and temperature b are below the preset specified range, the boiler discharge temperature and pressure evaluation index TP is 0.

7.

3. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 1, characterized in that, The exhaust air humidity evaluation index HU is obtained as follows: After the boiler is drained, the thermal equipment is dried by the air drying system. The humidity value c of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value d of the second online hygrometer installed at the turbine exhaust port are recorded. Before the unit of thermal equipment is started, the humidity value f of the first online hygrometer installed at the water-cooled wall exhaust port and the humidity value g of the second online hygrometer installed at the turbine exhaust port are recorded again. The average humidity is calculated based on humidity values ​​c, d, f, and g. The exhaust air humidity evaluation index HU is obtained based on this average humidity value. The exhaust air humidity evaluation index HU is specifically as follows: When the average humidity is less than 50%, the air humidity evaluation index HU is 1.0; When the average humidity is greater than or equal to 50% and less than 60%, the air humidity evaluation index HU is 0.9; When the average humidity is greater than or equal to 60% and less than 65%, the air humidity evaluation index HU is 0.8; When the average humidity is greater than or equal to 65%, the air humidity evaluation index HU is 0.

7.

4. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 1, characterized in that, The corrosion status evaluation index CO is obtained as follows: If the downtime of the thermal equipment exceeds a predetermined threshold, the corrosion plates installed in the water-cooled wall are inspected, the corrosion amount of the corrosion plates is detected, the corrosion rate e of the plates is calculated, and the corrosion status evaluation index CO is obtained. The corrosion status evaluation index CO is specifically: When the downtime is less than 30 days, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is lower than the standard control value, the corrosion status evaluation index CO is 1.0; When the downtime exceeds 30 days and the corrosion rate e of the coating is within the standard control range, the corrosion status evaluation index CO is 0.

9. When the downtime exceeds 30 days and the corrosion rate e of the coating exceeds the standard control value, the corrosion status evaluation index is 0.

8.

5. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 1, characterized in that, The evaluation indexes WQ (volume of start-up flushing water) and TU (turbidity of start-up flushing water) were obtained, specifically as follows: During the start-up flushing process of the thermal equipment, the maximum values ​​of the online turbidity meter h1, h2, h3, and h4 of the condensate pump outlet, deaerator outlet, separator drainage during cold flushing, and separator drainage during hot flushing are detected respectively, and the qualified flushing water volume q1, q2, q3, and q4 for each stage are calculated accordingly. The evaluation index WQ of the unit start-up flushing water volume is obtained by comparing the sum of qualified flushing water volumes q1, q2, q3, and q4 with the baseline water volume q. The turbidity evaluation index TU for unit start-up flushing is obtained by comparing the average values ​​of the maximum values ​​h1, h2, h3, and h4 of the online turbidity meter with the reference turbidity h.

6. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 5, characterized in that, The evaluation index WQ for unit start-up flushing water volume is as follows: When the total qualified flushing water volume of q1+q2+q3+q4 is less than 0.8 times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 1.0; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [0.8-1.0) times the benchmark water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.9; When the total qualified flushing water volume of q1+q2+q3+q4 is within the range of [1.0-1.2) times the reference water volume q, the evaluation index WQ of the unit start-up flushing water volume is 0.8; When the total qualified flushing water volume of q1+q2+q3+q4 is greater than or equal to 1.2q times the benchmark water volume q, the unit start-up flushing water volume evaluation index WQ is 0.

7.

7. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 5, characterized in that, The turbidity evaluation index TU for unit start-up flushing is as follows: When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is less than 0.8 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 1.

0. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is between 0.8 and 1.0 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.

9. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is within [1.0-1.2] times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.

8. When the average value of the online turbidity meter values ​​h1, h2, h3, and h4 is greater than or equal to 1.2 times the reference turbidity h, the turbidity evaluation index TU for unit start-up flushing is 0.

7.

8. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 1, characterized in that, A comprehensive evaluation system for the shutdown and maintenance of thermal equipment is constructed, with the specific expression as follows: Where I is the comprehensive maintenance effect evaluation value, and k1, k2, k3, k4, and k5 are all weighting coefficients. ; The comprehensive maintenance effect evaluation value I is compared with the preset threshold range, and the evaluation level of the maintenance effect is output.

9. The comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to claim 8, characterized in that, The evaluation levels for maintenance effectiveness are as follows: when At that time, the maintenance effect was rated as excellent; when At that time, the maintenance effect was rated as average; when At that time, the maintenance effect was rated as poor.

10. A system for implementing a comprehensive evaluation method for the shutdown and maintenance of thermal equipment according to any one of claims 1-9, characterized in that, include: The first online hygrometer is installed at the exhaust port of the water-cooled wall of the thermal equipment; A second online humidity meter installed at the turbine exhaust port of a thermal power plant; Multichannel online turbidity meters are installed at the condensate pump outlet, deaerator outlet, and economizer drain pipeline of thermal equipment. Corrosion-resistant plates installed inside the water-cooled walls of thermal equipment; The data acquisition and processing unit is used to acquire the readings of the hygrometer and turbidimeter, and to receive the inspection results of the corrosion pads; The index calculation unit is configured to perform the calculation steps and comprehensive evaluation system steps for the boiler discharge water temperature and pressure evaluation index TP, the exhaust air humidity evaluation index HU, the corrosion status evaluation index CO, the unit start-up flushing water volume evaluation index WQ, and the unit start-up flushing turbidity evaluation index TU. The output unit is used to output the evaluation level of the maintenance effect of the thermal equipment during shutdown.

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