Flue soot blowing method and system for improving boiler operation safety under low load

Abstract

The invention relates to a flue soot blowing method for improving boiler operation safety under low load, which comprises the following steps of: acquiring operation load, exhaust gas temperature and temperature difference of an inlet and an outlet of a high-temperature reheater in real time, and comparing optimal data in data sets of the exhaust gas temperature and steam temperature difference of the inlet and the outlet of the high-temperature reheater at different load sections; soot blowing operation is carried out after set conditions are met; the generation process of the optimal data set of each load section is as follows: under the steady-state load of a certain load section, after the last soot blowing is completed, the same coal type is used for continuous combustion, the exhaust gas temperature and the steam temperature difference of the inlet and the outlet of the high-temperature reheater are recorded, a data set is generated, optimization is carried out based on the data set, and the optimal data set is obtained. The set conditions comprise a first judgment condition set based on the exhaust gas temperature and a second judgment condition set based on the steam temperature difference of the inlet and the outlet of the high-temperature reheater; and the lowest exhaust gas temperature and the highest temperature difference of the inlet and the outlet of the high-temperature reheater corresponding to the load section are obtained. The invention further relates to a flue soot blowing system for improving the boiler operation safety under the low load, the flue soot blowing system comprises an air source unit and a soot blowing unit, and the flue soot blowing system executes the soot blowing operation. Compared with the prior art, a reasonable flue soot blowing scheme can be provided in real time, and production activity safety is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of coal-fired boiler operation safety, and in particular relates to a flue soot blowing method and system for improving boiler operation safety under low load. Background Art

[0002] When the unit is running at low load and deep peak load, the flue gas velocity in the boiler flue area is reduced. Too low a flue gas velocity cannot carry away the ash deposited in the flue area, especially for boilers burning high-ash coal. The height of ash deposits under low load can even reach more than 1 meter. When the negative pressure of the furnace fluctuates, the flue ash collapse is likely to occur, resulting in large fluctuations in the negative pressure of the furnace and burner extinguishing. In addition, serious flue ash accumulation will also lead to increased heat transfer resistance of the front and rear heating surfaces in the area, deterioration of heat exchange, increased exhaust gas temperature, reduced boiler efficiency, deformation of the water-cooled wall at the bottom of the flue, and because the height of the ash accumulation is flush with the lower steam soot blowing gun, the steam carries the ash during boiler soot blowing, increasing the wear rate of the high-temperature reheater tube row, reducing the heat exchange area of ​​the high-temperature reheater tube row and preventing the free downward expansion of the high-temperature and high-pressure reheater tube row, increasing the additional stress in the weld joints of the high-temperature and high-pressure reheater tubes and the weld seam area of ​​the slider, and easily causing cracks at the slider to cause tube bursts, seriously affecting the safe and reliable operation of the unit. Because the furnace combustion stability is much lower than that at high load during deep peak load regulation, in order to eliminate the serious impact of flue ash accumulation on boiler operation safety, it is necessary to evaluate the boiler flue soot blowing method based on actual coal burning and operation conditions.

[0003] When the ash content of coal is high and the flue gas flow rate is low under low load, ash accumulation occurs during boiler flue operation.

[0004] At present, researchers have conducted a lot of research on boiler heating surface pollution status monitoring and sootblowing optimization, proposed a variety of heating surface pollution status monitoring methods and developed corresponding online monitoring and sootblowing optimization systems, which can be applied to different types of coal-fired boilers. However, the problem of flue ash accumulation under low load has not attracted much attention. For example, Chinese patent application 202010502918.1 proposed a furnace sootblowing method, which fits the pollution rate curve during ash accumulation and the pollution rate during sootblowing with historical furnace pollution data to obtain a sootblowing optimization model, solve the upper and lower limits of the critical pollution rate, the reasonable ash accumulation time and the sootblowing time, and then control the start and stop of the furnace sootblowing. However, the above method uses historical operating messy data as samples for data analysis, and does not combine the actual operating conditions of the combustion mechanism for analysis. There may be a large gap with the ideal state when it is actually applied. For another example, Chinese patent application 202110777782.X proposes an intelligent sootblowing control method, system and medium based on multi-dimensional evaluation factors, selects multiple boiler operating parameters as evaluation factors for selecting sootblowers, and groups each evaluation factor into priority levels according to the impact of each evaluation factor on boiler safety, the impact on economic operation, and the degree of correlation with heating surface contamination. The number of evaluation factors in each priority level whose values ​​are not within the normal range is counted, and the need for sootblowing is determined based on the number of evaluation factors in each priority level whose values ​​are not within the normal range. The above method has the phenomenon of too many choices and mixed coupling in the selection of online parameters. At the same time, since there is no obvious breakthrough in the relevant monitoring technology of the pollution status of the heating surface in the coal-fired boiler furnace, similar systems have not been actually put into operation in most power plants, and there is no sootblowing method and system for serious flue ash accumulation under low load. Therefore, it is necessary to design a simple flue soot blowing method and system to improve the safety of boiler operation under low load, which can provide a reasonable soot blowing plan in real time to ensure the safety of production activities. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a flue soot blowing method and system for improving the safety of boiler operation under low load, which can provide a reasonable soot blowing plan in real time to ensure the safety of production activities.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a flue soot blowing method for improving boiler operation safety under low load, comprising the following steps:

[0008] Obtain the operating load, exhaust temperature, and high-temperature reheater inlet and outlet temperature difference in real time, compare the optimal data in the data sets of exhaust temperature and high-temperature reheater inlet and outlet steam temperature difference at different load sections, and perform soot blowing operation after the set conditions are met;

[0009] The generation process of the optimal data set for each load segment is as follows:

[0010] Under a steady-state load in a certain load section, after the last soot blowing is completed, the same type of coal is used for continuous combustion, the exhaust gas temperature and the high-temperature reheater inlet and outlet steam temperature difference are recorded, and a data set is generated. Based on the data set, optimization is performed to obtain the minimum exhaust gas temperature and the maximum high-temperature reheater inlet and outlet temperature difference corresponding to the load section;

[0011] The set conditions include a first determination condition set based on the exhaust gas temperature and a second determination condition set based on the high temperature reheater inlet and outlet steam temperature difference.

[0012] Furthermore, when different types of coal are used in different load sections, the optimization method is consistent.

[0013] Furthermore, the method for optimizing based on the data set includes a particle swarm optimization algorithm.

[0014] Furthermore, the specific process of performing the soot blowing operation when the first determination condition is met is as follows:

[0015] When the ratio of the exhaust temperature obtained in real time to the exhaust temperature of the optimal solution obtained by optimizing the data set reaches a first set threshold, a contamination warning is issued and a soot blowing operation is performed after 15 minutes.

[0016] Furthermore, the specific process of performing the soot blowing operation when the second determination condition is met is as follows:

[0017] When the real-time high-temperature reheater inlet and outlet steam temperature difference and the high-temperature reheater inlet and outlet steam temperature difference of the optimal solution obtained by optimizing the data set are less than the second set threshold, a contamination warning is issued and soot blowing operation is performed after 15 minutes.

[0018] The present invention also provides a flue soot blowing system for improving boiler operation safety under low load, comprising an air source unit and a soot blowing unit:

[0019] The gas source unit adopts steam as the soot blowing medium, and the gas source is taken from the inlet steam of the final superheater of the power plant or the cold re-inlet steam. The unit includes a manual ball valve, a soot blowing main valve, a pressure gauge, a soot blowing main pipe, and several soot blowing branch pipes.

[0020] Optionally, the sootblowing mother pipe and the sootblowing branch pipe are made of seamless steel pipes made of 20# steel.

[0021] The sootblowing unit adopts 4 sets of hood-type pneumatic sootblower (2 sets on each side), and the hood cover is made of ZG0Cr25Ni20MoMnSiNRe material, which has high temperature resistance and corrosion resistance.

[0022] Optionally, to prevent wear, an anti-wear cover plate is arranged around the nozzle to prevent the sootblowing medium from damaging the heating surface tubes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention proposes a flue soot blowing method for improving boiler operation safety under low load, which obtains the operation load, exhaust gas temperature, and high-temperature reheater inlet and outlet temperature difference in real time, compares the optimal data in the data sets of exhaust gas temperature and high-temperature reheater inlet and outlet steam temperature difference at different load sections, and performs soot blowing operation after the set conditions are met;

[0025] First, the operating load, exhaust temperature, and high-temperature reheater inlet and outlet temperature difference are obtained in real time. Then, the optimal data in the data sets of exhaust temperature and high-temperature reheater inlet and outlet steam temperature difference in different load sections are compared, and soot blowing operation is performed after the set conditions are met; specifically, under the steady-state load of a certain load section, after the last soot blowing is completed, the same type of coal is used for continuous combustion, and the exhaust temperature and high-temperature reheater inlet and outlet steam temperature difference are recorded to generate a data set, and optimization is performed based on the data set to obtain the minimum exhaust temperature and the maximum high-temperature reheater inlet and outlet temperature difference corresponding to the load section; the set conditions include a first judgment condition set based on the exhaust temperature, when the ratio of the exhaust temperature obtained in real time to the exhaust temperature of the optimal solution obtained by optimizing the data set reaches a first set threshold, a contamination warning is issued, and a soot blowing operation is performed 15 minutes later; the set conditions also include when the high-temperature reheater inlet and outlet steam temperature difference obtained in real time and the high-temperature reheater inlet and outlet steam temperature difference of the optimal solution obtained by optimizing the data set reach a second set threshold, a contamination warning is issued, and a soot blowing operation is performed 15 minutes later. The above method only needs to collect three key parameters of the boiler. It has the advantages of accurate judgment, low cost, convenient implementation, and easy promotion, which is conducive to the safe and stable operation of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process of the present invention;

[0027] Figure 2 The figure is a flow chart of the sootblowing system. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0029] Example:

[0030] This embodiment provides a flue soot blowing method for improving boiler operation safety under low load. Figure 1 As shown, the following steps are included:

[0031] S1. Use the particle swarm optimization algorithm to generate the optimal data in the data set of exhaust gas temperature and high-temperature reheater inlet and outlet steam temperature difference at different load sections. The specific process is as follows:

[0032] Due to the complex and changeable operation state of the boiler, in the actual operation process, after soot blowing in multiple stable load sections (300MW, 280MW, 260MW, 240MW, 220MW, 200MW, 180MW), the temperature was observed to be stable. It was found that the temperature could reach the lowest value and stable state 30 minutes after the soot blowing. Therefore, the state 30 minutes after the soot blowing was taken as the starting point to collect the data set of exhaust temperature and high temperature reheater inlet and outlet steam temperature difference. Under the steady-state load of a certain load section, the data set of exhaust temperature and high temperature reheater inlet and outlet steam temperature difference was obtained, and the particle swarm optimization algorithm was used to generate the optimal data in the data set of exhaust temperature and high temperature reheater inlet and outlet steam temperature difference of different load sections.

[0033] In particular, when different load sections use different types of coal, the optimization method is consistent.

[0034] S2. Obtain the current operating load, exhaust gas temperature and high-temperature reheater inlet and outlet steam temperature difference in real time.

[0035] S3. Compare the optimal data in the data set of the exhaust gas temperature in each load section and the high-temperature reheater inlet and outlet steam temperature difference, and perform soot blowing operation after the set conditions are met.

[0036] The setting conditions include a first judgment condition based on the exhaust gas temperature setting and a second judgment condition based on the high-temperature reheater inlet and outlet steam temperature difference setting, wherein the specific process of soot blowing operation when the first judgment condition is met is as follows: when the ratio of the exhaust gas temperature obtained in real time to the exhaust gas temperature of the optimal solution obtained by optimizing the data set reaches the first set threshold value (1.07), a contamination warning is issued, and soot blowing operation is performed after 15 minutes. The specific process of soot blowing operation when the second judgment condition is met is as follows: when the ratio of the high-temperature reheater inlet and outlet steam temperature difference obtained in real time to the high-temperature reheater inlet and outlet steam temperature difference of the optimal solution obtained by optimizing the data set is less than the second set threshold value (0.95), a contamination warning is issued, and soot blowing operation is performed after 15 minutes.

[0037] The above method only needs to collect, calculate and analyze data under the actual stable operating conditions of the boiler based on the three key data of the boiler's existing operating load, exhaust gas temperature, and high-temperature reheater inlet and outlet steam temperature difference. The overall contamination state of the boiler can be judged by comparing the actual value with the benchmark value under the actual boiler operating state. It has the advantages of accurate judgment, low cost, convenient implementation, and easy promotion. The soot blowing method of the power plant can be guided according to the contamination state, which is beneficial to the safe and stable operation of the boiler.

[0038] If the above method is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0039] This embodiment provides a flue soot blowing system for improving boiler operation safety under low load. Figure 2 As shown, the system at least includes a manual ball valve 1, a sootblowing main valve 2, a pressure gauge 3, a sootblowing main pipe 4, a sootblowing branch pipe 5, and a hood-type pneumatic sootblower 6.

[0040] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art, and can be applied to, including but not limited to, π-type boilers and tower boilers. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A flue soot blowing method for improving boiler operation safety under low load, characterized in that: The following steps are involved: Obtain the operating load, exhaust temperature, and high-temperature reheater inlet and outlet temperature difference in real time, compare the optimal data in the data sets of exhaust temperature and high-temperature reheater inlet and outlet steam temperature difference at different load sections, and perform soot blowing operation after the set conditions are met; The generation process of the optimal data set for each load segment is as follows: Under a steady-state load in a certain load section, after the last soot blowing is completed, the same type of coal is used for continuous combustion, the exhaust gas temperature and the high-temperature reheater inlet and outlet steam temperature difference are recorded, and a data set is generated. Based on the data set, optimization is performed to obtain the minimum exhaust gas temperature and the maximum high-temperature reheater inlet and outlet temperature difference corresponding to the load section; The set conditions include a first determination condition set based on the exhaust gas temperature and a second determination condition set based on the high temperature reheater inlet and outlet steam temperature difference.

2. A flue soot blowing method for improving boiler operation safety under low load according to claim 1, characterized in that: When different types of coal are used in different load sections, the optimization method is the same.

3. A flue soot blowing method for improving boiler operation safety under low load according to claim 1, characterized in that: The method used for optimization based on the data set includes a particle swarm optimization algorithm.

4. A flue soot blowing method for improving boiler operation safety under low load according to claim 1, characterized in that: The specific process of performing the soot blowing operation when the first determination condition is met is as follows: When the ratio of the exhaust temperature obtained in real time to the exhaust temperature of the optimal solution obtained by optimizing the data set reaches a first set threshold, a contamination warning is issued and a soot blowing operation is performed after 15 minutes.

5. A flue soot blowing method for improving boiler operation safety under low load according to claim 1, characterized in that: The specific process of performing the soot blowing operation when the second determination condition is met is as follows: When the real-time high-temperature reheater inlet and outlet steam temperature difference and the high-temperature reheater inlet and outlet steam temperature difference of the optimal solution obtained by optimizing the data set are less than the second set threshold, a contamination warning is issued and soot blowing operation is performed after 15 minutes.

6. A flue soot blowing system for improving boiler operation safety under low load, characterized in that: It includes air source unit and soot blowing unit.

7. A flue soot blowing system for improving boiler operation safety under low load according to claim 6, characterized in that: The gas source unit adopts steam as the soot blowing medium, and the gas source is taken from the inlet steam of the final superheater of the power plant or the cold re-inlet steam. The unit includes a manual ball valve, a soot blowing main valve, a pressure gauge, a soot blowing main pipe, and several soot blowing branch pipes.

8. A flue soot blowing system for improving boiler operation safety under low load according to claim 6, characterized in that: The sootblowing main pipe and sootblowing branch pipe are made of seamless steel pipe, the material is 20# steel.

9. A flue soot blowing system for improving boiler operation safety under low load according to claim 6, characterized in that: The sootblowing unit adopts 4 sets of hood-type pneumatic sootblower (2 sets on each side), and the hood cover is made of ZG0Cr25Ni20MoMnSiNRe material, which has high temperature resistance and corrosion resistance.

10. A flue soot blowing system for improving boiler operation safety under low load according to claim 6, characterized in that: To prevent wear, anti-wear covers are arranged around the nozzles to prevent the sootblowing medium from damaging the heating surface tubes.

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