Opposite-firing boiler bottom air leakage rate measuring method suitable for diversified combustion

Abstract

According to the opposed firing boiler bottom air leakage rate measuring method suitable for diversified combustion, the boiler bottom air leakage rate is determined by measuring the primary air volume and the secondary air volume and calculating the total air volume of the boiler; the method comprises the specific implementation steps of relieving AGC operation, stabilizing unit load and operation parameters, setting oxygen quantity and air quantity measuring points at key positions, keeping coal quality stable, recording air quantity data in different states and the like. According to the method, the boiler bottom air leakage amount is effectively quantified, the accurate air leakage rate is obtained through comparative analysis with the boiler air supply amount, meanwhile, a relation curve of the optimal air leakage rate and the smoke exhaust temperature is obtained by adjusting an air door of the dry slag extractor, and a basis is provided for optimization control under different loads. The application of the method achieves the effects of improving the operation safety and economy of the boiler, reducing the emission of nitrogen oxides and reducing the high-temperature corrosion risk of the water cooling wall, so that the overall performance and the environmental protection level of a thermal power plant are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers in thermal power plants, and particularly relates to a method for measuring the air leakage rate at the bottom of a opposed firing boiler suitable for diversified combustion. Background Art

[0002] The air-cooled dry slag removal system has the advantages of low water consumption, high bottom slag utilization rate, small environmental impact, simple system maintenance and good comprehensive benefits, and is widely used in domestic large-scale power station boilers. The energy-saving effect of the air-cooled dry slag removal system is mainly reflected in the recovery of the physical sensible heat of the slag and the heat released by its re-combustion by the cooling air sucked into the furnace bottom. However, if the temperature of the cooling air sucked into the furnace bottom is relatively low, it still acts as air leakage at the furnace bottom. When the total air volume in the furnace remains unchanged, it will cause a decrease in the air volume passing through the air preheater and an increase in the flue gas temperature. Therefore, there is an optimal air leakage rate for the dry slag removal system at a certain load. When the air leakage rate is less than this value, its impact on the boiler economy is positive, and when the air leakage rate is greater than this value, the economy of the boiler will decrease.

[0003] Currently, the dry slag removal system generally has the problem of a high air leakage rate, and it deviates significantly from the designed value of 1% of the air leakage rate. The air leakage rate at the bottom of some units exceeds 10%. The high air leakage rate at the furnace bottom leads to a decrease in boiler efficiency, an increase in the flame center in the furnace, an increase in nitrogen oxides, an increase in the desuperheating water volume, an increase in the furnace outlet temperature, an increase in the risk of boiler slagging, an increase in unorganized air leakage at the furnace bottom, a decrease in organized air intake, affecting the air flow field in the furnace, resulting in a strongly reducing atmosphere in the gas adhering to the water wall, and an increase in the risk of high-temperature corrosion of the water wall. Therefore, in order to ensure the safe and stable operation of the boiler, it is necessary to reduce and control the air leakage rate of the unorganized air leakage in the dry slag removal system.

[0004] Currently, the main methods for testing the air leakage volume of the dry slag removal system are the heat balance calculation method and the direct measurement method. The heat balance calculation method does not consider the heat released by the re-combustion of the slag, and it is difficult to accurately measure each parameter. Since the direct measurement method cannot test the air leakage of its own body, this method is applicable to the dry slag removal system with good tightness. The dry slag removal system is large in volume and has many rotating parts, and it is difficult to solve the problem of air leakage of its own body from the structure and principle. Therefore, it is very necessary to find a simple and feasible method for testing the air leakage rate of the dry slag removal system. Summary of the Invention

[0005] In the first aspect of the present disclosure, there is provided a method for measuring the air leakage rate at the bottom of a opposed firing boiler suitable for diversified combustion, including the following steps:

[0006] S1: Control the unit load to be stable, and maintain the furnace negative pressure and the operating oxygen content constant;

[0007] S2: Keep the coal feeding amount of the coal mill stable, and control the primary air fan, the forced draft fan and the induced draft fan to be in the automatic operation mode;

[0008] S3: Set an oxygen content measuring point at the outlet of the economizer, and set a primary air flow measuring point and a secondary air flow measuring point on the primary hot air main pipe and the secondary hot air main pipe at the outlet of the air preheater respectively;

[0009] S4: After the unit reaches the preset load and operates stably, keep the shut-off door of the slag discharger fully open, continuously measure and record the primary air flow rate Q 11 and the secondary air flow rate Q 21 , close the shut-off door of the slag discharger, and after the unit operates stably, continuously measure and record the primary air flow rate Q 12 and the secondary air flow rate Q 22 ;

[0010] S5: Based on the measured air flow data, calculate the bottom leakage air flow rate ΔQ = (Q 12 +Q 22 ) - (Q 11 +Q 21 );

[0011] S6: Combine with the total boiler air supply volume Q, and calculate the bottom leakage air rate η = ΔQ / Q.

[0012] Combined with the first aspect, record the primary air flow rate Q 11 and the secondary air flow rate Q 21 , record the primary air flow rate Q 12 and the secondary air flow rate Q 22 The measurement time lasts for 5 minutes, data is collected every 10 seconds, and the average value is finally taken;

[0013] Close the shut-off door of the slag discharger, and after the unit operates for 30 minutes, continuously measure and record the primary air flow rate Q 12 and the secondary air flow rate Q 22 .

[0014] Combined with the first aspect, the coal quality parameters are obtained in real time through coal quality test data or the reference values of the designed coal type are adopted.

[0015] Combined with the first aspect, it further includes the following steps:

[0016] Change the bottom leakage air flow rate ΔQ by adjusting the opening degree of the inlet air damper of the dry slag discharger, and simultaneously record the flue gas temperature;

[0017] Fit the relationship curve between the bottom leakage air rate η and the flue gas temperature, and take the leakage air rate corresponding to the lowest point of the flue gas temperature as the optimal control value under the current load.

[0018] Combined with the first aspect, it further includes:

[0019] Repeat steps S1 - S6 for different loads to establish the corresponding relationship curve between the load and the optimal bottom leakage air rate;

[0020] Preset the curve into the boiler DCS control system, and compare the measured air leakage rate online with the curve target value in real time. When the deviation exceeds the preset threshold, an alarm is triggered.

[0021] In combination with the first aspect, during the test, it is necessary to ensure stable coal quality, no soot blowing operation in the boiler, and no combustion-supporting facilities are put into use.

[0022] In combination with the first aspect, the total boiler air supply volume Q is determined by the following formula:

[0023]

[0024] where D is the average coal feeding amount, O2 is the average oxygen content at the economizer outlet, and V k is the theoretical air volume.

[0025] In combination with the first aspect, the formula for calculating the theoretical air volume is:

[0026] V k = 0.0889×(C ar + 0.375S ar ) + 0.265H ar - 0.0333O ar ,

[0027] where C ar , S ar , H ar , O ar are the carbon, sulfur, hydrogen, and oxygen contents of the as-received coal entering the furnace, respectively.

[0028] In the second aspect of the present disclosure, there is provided an electronic device, including:

[0029] One or more processors;

[0030] A storage unit for storing one or more programs, which, when executed by the one or more processors, can enable the one or more processors to implement the method for measuring the bottom air leakage rate of a opposed firing boiler applicable to diversified combustion.

[0031] In the third aspect of the present disclosure, there is provided a computer-readable storage medium, on which a computer program is stored, characterized in that when the computer program is executed by a processor, it can implement the method for measuring the bottom air leakage rate of a opposed firing boiler applicable to diversified combustion.

[0032] Beneficial effects: A method for measuring the air leakage rate at the bottom of a opposed firing boiler suitable for diversified combustion provided by the present disclosure determines the air leakage rate at the bottom of the boiler by measuring the primary and secondary air volumes and calculating the total air volume of the boiler. The specific implementation steps include releasing AGC operation, stabilizing the unit load and operating parameters, setting oxygen and air volume measuring points at key positions, maintaining stable coal quality, and recording air volume data under different states, etc. This method effectively quantifies the air leakage volume at the bottom of the boiler, and obtains an accurate air leakage rate through comparative analysis with the boiler air supply volume. At the same time, by adjusting the damper of the dry slag conveyor, the relationship curve between the optimal air leakage rate and the flue gas temperature is obtained, providing a basis for optimized control under different loads. The application of this method achieves the effects of improving the operating safety and economy of the boiler, reducing nitrogen oxide emissions, and reducing the risk of high-temperature corrosion of the water wall, thereby improving the overall performance and environmental protection level of thermal power plants. Description of the Drawings

[0033] Figure 1 It is a schematic flow chart of a method for measuring the air leakage rate at the bottom of an opposed firing boiler suitable for diversified combustion according to an embodiment of the present disclosure;

[0034] Figure 2 It is an electronic device according to an embodiment of the present disclosure. Detailed Implementation Modes

[0035] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the embodiments of the present disclosure.

[0036] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present disclosure. The singular forms "a", "the" and "said" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0037] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present disclosure to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the embodiments of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0038] Such as Figure 1FIG. 1 is a flow chart of a method for measuring the bottom air leakage rate of a counter-firing boiler applicable to diversified combustion according to an embodiment of the present disclosure, including:

[0039] S1: Control the unit load to be stable and maintain the furnace negative pressure and operating oxygen content constant.

[0040] Specifically, during boiler operation, unit load stability is a key factor in ensuring measurement accuracy. Load fluctuations can affect fuel combustion, leading to changes in furnace pressure and oxygen levels. Therefore, before measuring bottom air leakage, the unit load must be adjusted to the target load and maintained for a period of time to ensure stable boiler combustion.

[0041] Controlling furnace negative pressure is crucial for safe boiler operation. Excessive negative pressure can cause excessive stress on the furnace, potentially affecting combustion stability; while excessively low negative pressure can cause flue gas to leak out of the furnace, impacting boiler efficiency. Therefore, during measurement, furnace negative pressure should be continuously monitored and maintained within the set range by adjusting the induced draft fan operating parameters.

[0042] The stability of the operating oxygen level (i.e., the oxygen level at the economizer outlet) is directly related to combustion efficiency and emission control. Large fluctuations in the oxygen level may indicate changes in combustion conditions, which can affect air flow distribution and, consequently, furnace bottom air leakage measurement. Therefore, before measurement, it is important to ensure that the operating oxygen level remains constant and to avoid fluctuations due to combustion adjustments or other changes in operating conditions.

[0043] The above three control conditions (unit load, furnace negative pressure and operating oxygen content) work together to ensure that the operating state of the boiler is as stable as possible during the measurement process, providing a reliable basis for subsequent data collection.

[0044] S2: Keep the coal feed rate of the coal mill stable and control the primary fan, forced draft fan and induced draft fan in automatic operation mode.

[0045] Specifically, during this step, the stability of the coal feed to the pulverizer directly impacts the boiler's combustion efficiency and stability. Large fluctuations in the coal feed can lead to variations in combustion intensity, which in turn affects airflow distribution within the furnace and exhaust gas temperature. Therefore, maintaining a constant coal feed to the pulverizer is a prerequisite for stable boiler operation and accurate air leakage measurement.

[0046] To this end, before measuring air leakage, the coal feed rate to the pulverizer must be adjusted to an appropriate level and switched to manual control mode to avoid unnecessary fluctuations introduced by automatic control. Simultaneously, the coal feed rate to the pulverizer must be monitored to ensure continuity and stability.

[0047] Meanwhile, as the main air supply equipment in the boiler system, the primary air fan, forced draft fan, and induced draft fan have their operating states affecting the air flow and oxygen supply in the furnace. If these fans are in the manual adjustment mode, it may cause uneven distribution of the air flow, further affecting the pneumatic characteristics in the furnace and the measurement results. Therefore, it is necessary to ensure that all fans are in the automatic control mode, automatically adjusting the air pressure and volume, and ensuring that the fans provide sufficient and balanced air supply according to the real-time boiler operation requirements.

[0048] S3: Set an oxygen content measurement point at the outlet of the economizer, and set a primary air volume measurement point and a secondary air volume measurement point at the hot primary air header and the hot secondary air header at the outlet of the air preheater respectively.

[0049] Specifically, the main purpose of setting an oxygen content measurement point at the outlet of the economizer is to monitor the oxygen content in the boiler flue gas. Oxygen content is an important indicator to measure the combustion condition of the boiler. If the combustion is sufficient, the oxygen content should be maintained within a certain range. Too low oxygen content usually means that excessive fuel is not completely burned, and too high may indicate excessive air supply. Measuring the oxygen content at the outlet of the economizer can monitor the combustion efficiency of the boiler in real time and provide a basis for subsequent adjustment of the air volume and combustion system. In addition, setting a primary air volume measurement point and a secondary air volume measurement point at the hot primary air header and the hot secondary air header at the outlet of the air preheater respectively is also to accurately measure the flow rates of different levels of air in the boiler.

[0050] The primary air is the air that directly enters the furnace to mix with the fuel and plays a role in the initial combustion, while the secondary air is the air volume that further assists combustion and controls the furnace temperature after the primary air has partially completed combustion. By measuring the primary air volume (Q1) and the secondary air volume (Q2) respectively, the air distribution can be accurately recorded, providing key data for measuring the furnace bottom air leakage rate.

[0051] Setting the positions of these measurement points can ensure the diversity and comprehensiveness of data collection, and also improve the accuracy and reliability of the measurement results. By monitoring these air volume and oxygen content data in real time, the operation efficiency of the boiler and whether there is an air leakage problem can be further analyzed, providing valuable operation data support.

[0052] S4: After the unit reaches the preset load and operates stably, keep the slag discharge gate shut-off valve fully open, continuously measure and record the primary air volume Q 11 and the secondary air volume Q 21 , close the slag discharge gate shut-off valve, and after the unit operates stably, continuously measure and record the primary air volume Q 12 and the secondary air volume Q 22 .

[0053] Specifically, after the unit reaches the preset load and operates stably, keep the slag discharge gate shut-off valve fully open, continuously measure and record the primary air volume Q 11 and the secondary air volume Q 21, close the slag discharge gate shut-off door. After the unit operates stably, continuously measure and record the primary air volume Q once. 12 and the secondary air volume Q 22 .

[0054] This process is divided into two stages. The purpose is to accurately calculate the air leakage volume at the furnace bottom by comparing the air volume data under different operating conditions. The specific description is as follows:

[0055] The first stage: Measurement when the slag discharge gate shut-off door is fully open.

[0056] Operating conditions: After the unit reaches the preset load and operates stably, keep the slag discharge gate shut-off door in the fully open state.

[0057] Measurement purpose: When the slag discharge gate shut-off door is fully open, the air flow situation in the furnace bottom area is in a relatively "natural" state. At this time, the measured primary air volume (Q 11 ) and the secondary air volume (Q 21 ) reflect the air volume distribution in the open state.

[0058] Data acquisition method: Adopt the continuous measurement method. Usually, data is collected every 10 seconds within a fixed period of time (such as 5 minutes), and then the average value is taken to ensure the representativeness and stability of the data.

[0059] The second stage: Measurement when the slag discharge gate shut-off door is closed.

[0060] Operating conditions: After completing the measurement in the first stage, close the slag discharge gate shut-off door. This changes the air flow path and forces some air to enter or leave the furnace bottom area through other channels.

[0061] Wait for stability: After closing the door, wait for the unit to operate stably (such as 30 minutes) to enable the system to reach a new equilibrium state and avoid the impact of instantaneous fluctuations caused by operation changes on data acquisition.

[0062] Measurement purpose: Under the stable state, continuously measure the primary air volume (Q 12 ) and the secondary air volume (Q 22 ). Similarly, collect data every 10 seconds within a fixed time and take the average value to ensure that the data accurately reflects the air flow situation when the door is closed.

[0063] Data comparison and significance: By comparing the measurement data of the two stages, the air leakage volume ΔQ at the furnace bottom can be calculated, that is:

[0064] ΔQ = (Q 12 + Q 22 ) - (Q 11 + Q 21 ),

[0065] This method uses the on-off state of the slag discharge gate to isolate and measure the air volume change caused by air leakage at the furnace bottom, thereby providing a reliable data basis for subsequent calculation of the air leakage rate at the furnace bottom.

[0066] S5: Based on the measured air volume data, calculate the air leakage volume at the furnace bottom ΔQ = (Q 12 + Q 22 ) - (Q 11 + Q 21 ).

[0067] Specifically, first, the primary air volume Q 11 and the secondary air volume Q 21 measured when the slag discharge gate is fully open represent the air flow situation in the "normal" state, including the air required for combustion and part of the air flow possibly caused by air leakage; while after closing the slag discharge gate, the primary air volume Q 12 and the secondary air volume Q 22 measured after the system stabilizes reflect the state after changing the air flow path.

[0068] Then, add the air volume data in the two states respectively to obtain the total air volume when the door is fully open and when the door is closed. The difference between the two, that is, ΔQ = (Q 12 + Q 22 ) - (Q 11 + Q 21 ), reflects the air volume change caused by the change in the state of the slag discharge gate. This change is mainly attributed to the change in the air leakage volume at the furnace bottom, because after closing the door, part of the air cannot directly enter or exit through the original channel and must compensate for this change through other air leakage paths, thus causing a difference in the measured total air volume.

[0069] Therefore, through the above calculation, the additional air flow caused by air leakage at the furnace bottom can be accurately separated, providing a reliable data basis for subsequent calculation of the air leakage rate at the furnace bottom according to the total air supply volume of the boiler.

[0070] S6: Combine the total air supply volume Q of the boiler and calculate the air leakage rate η = ΔQ / Q.

[0071] Specifically, first, use the air leakage volume ΔQ obtained in the previous steps, and then combine it with the total air supply volume Q of the boiler to calculate the air leakage rate η through the formula η = ΔQ / Q. The air leakage rate η here reflects the proportion of air that fails to effectively participate in combustion due to system air leakage during the total air supply process of the boiler.

[0072] The total boiler air supply volume Q represents all the air entering the boiler combustion chamber, including the normal air for combustion and the air leakage caused by imperfect structural sealing. By calculating the ratio of the air leakage volume to the total air supply volume, the proportion of air leakage in the entire air supply system can be intuitively understood, thereby evaluating the boiler's airtightness and operating efficiency.

[0073] If the air leakage rate η is high, it means that a large amount of air does not participate in the normal combustion process, which may lead to problems such as reduced combustion efficiency, heat energy waste, and increased flue gas temperature. At the same time, it may also cause safety hazards and excessive environmental emissions. On the contrary, a lower air leakage rate indicates that the system operates more tightly, can effectively utilize the supplied air, and thus ensure the sufficiency and economy of combustion.

[0074] Therefore, by calculating η, operators can monitor and adjust the boiler operating status in a timely manner, take necessary measures to reduce the air leakage rate, and ensure the safe, economic, and efficient operation of the boiler.

[0075] Furthermore, record the primary air volume Q 11 and the secondary air volume Q 21 、Record the primary air volume Q 12 and the secondary air volume Q 22 The measurement time for both lasts for 5 minutes, data is collected every 10 seconds, and the average value is finally taken.

[0076] Specifically, choosing 5 minutes as the measurement time for data collection can ensure obtaining sufficient data in a short time to reflect the true state of the system under the current working conditions. At the same time, this time period will neither be affected by external interference due to being too long nor lack representativeness due to being too short.

[0077] The sampling interval, with data collected every 10 seconds, can capture short-term fluctuations and occasional anomalies in the air flow rate. A shorter sampling interval helps to reduce the impact of instantaneous disturbances (such as small fluctuations or external interference) on the overall data.

[0078] Taking the average value of these 30 data points can effectively smooth out random noise and instantaneous fluctuations, obtaining a stable and reliable air volume representative value. This method ensures the accuracy and repeatability of the data, providing a solid foundation for the subsequent calculation of the air leakage volume and air leakage rate.

[0079] Through this continuous and regular data collection method, not only the measurement accuracy is improved, but also the changes in the unit operating status can be reflected in a timely manner during actual operation, providing key support for the safe and economic operation of the boiler.

[0080] Furthermore, the coal quality parameters are obtained in real time through coal quality test data or the reference values of the designed coal type are adopted.

[0081] Specifically, to ensure the accurate calculation of the boiler air supply volume and the theoretical air volume, it is necessary to accurately master the chemical composition of the coal fed into the furnace. The coal quality parameters include the carbon content on a certain basis (C ar ), the sulfur content on a certain basis (S ar ), the hydrogen content on a certain basis (H ar ), and the oxygen content on a certain basis (O ar ). These data directly affect the calculation of the theoretical air volume V k and thus affect the air ratio control of the entire combustion process. <X

[0082] In practical applications, the specific chemical composition of the current fuel can be obtained in real time through an on-line coal quality analyzer or regular coal quality testing. This method can promptly reflect the fluctuations in coal quality and ensure that when the coal type or quality changes, the calculations of the theoretical air volume and the boiler air supply volume can be dynamically adjusted to ensure that the combustion efficiency and emission indicators are always in the best state.

[0083] In cases where the coal quality fluctuations are small or the on-line detection conditions are limited, the coal type reference values determined in the design stage can also be used as coal quality parameters. These reference values are determined through a large number of experiments and data analyses during system design and can be used as a reference basis under stable operating conditions. However, when using the reference values, it is necessary to pay attention to regular calibration to ensure their consistency with the actual fuel quality, otherwise calculation errors may be introduced.

[0084] Beneficial effects: Through the flexible selection of these two methods, the accuracy and timeliness of coal quality parameters can be effectively guaranteed, providing reliable data support for the subsequent accurate calculation of the theoretical air volume and the total boiler air supply volume, thereby further improving the accuracy of the air leakage rate measurement and the overall efficiency of boiler operation.

[0085] Furthermore, it also includes the following steps:

[0086] Change the air leakage rate ΔQ at the furnace bottom by adjusting the opening degree of the air inlet damper of the dry slag extractor, and simultaneously record the flue gas temperature;

[0087] Fit the relationship curve between the air leakage rate η at the furnace bottom and the flue gas temperature, and use the air leakage rate corresponding to the lowest point of the flue gas temperature as the optimal control value under the current load.

[0088] Specifically, by adjusting the opening degree of the air inlet damper of the dry slag extractor, the air flow situation in the furnace bottom area can be changed, thereby causing the air leakage rate ΔQ at the furnace bottom to change. When the opening degree of the air inlet damper is small, the auxiliary air entering the furnace bottom decreases, which may lead to a reduction in the air volume of some air leakage paths; while when the opening degree of the air inlet damper increases, the air volume entering the furnace bottom increases, and correspondingly the air leakage rate also changes. During the adjustment process, the flue gas temperature is simultaneously recorded because the flue gas temperature is an important indicator reflecting the combustion efficiency and heat recovery situation. Recording this temperature data helps to understand the specific impact of the air flow change on the combustion and heat transfer states.

[0089] During the process of adjusting the air intake damper, by collecting the flue gas temperature data corresponding to different air leakage rates η (calculated from the air leakage volume ΔQ and the total boiler air supply volume Q), the relationship curve between the two can be plotted. This curve usually shows a "U" shape or a similar trend, that is, within a certain range, as the air leakage rate changes, the flue gas temperature will first decrease and then increase. The lowest point of the flue gas temperature represents that under the current load condition, the air leakage rate at the furnace bottom reaches an optimal control state, at which time the heat recovery effect is the best, the combustion efficiency is the highest, and the energy loss is the smallest. By fitting this relationship curve, the air leakage rate corresponding to the lowest flue gas temperature can be accurately found and used as the optimal control value under the current load.

[0090] This method can provide a basis for dynamic optimization in actual operation, enabling operators to adjust the air intake damper parameters in a timely manner to ensure that the boiler can achieve the best combustion efficiency and heat energy utilization under different working conditions.

[0091] Furthermore, it further includes:

[0092] Repeat steps S1 - S6 for different loads to establish the corresponding relationship curve between the load and the optimal air leakage rate at the furnace bottom;

[0093] Pre-set the curve into the boiler DCS control system, and compare the online measured air leakage rate with the curve target value in real time. When the deviation exceeds the preset threshold, an alarm is triggered.

[0094] Specifically, since the optimal air leakage rate at the furnace bottom of the boiler will be different under different load conditions, it is necessary to repeat steps S1 - S6 for multiple load conditions to obtain the air leakage rate η at the furnace bottom and the corresponding flue gas temperature data under different loads. Through data analysis, the optimal air leakage rate corresponding to each load point can be determined, that is, the air leakage rate value with the highest combustion efficiency and the smallest heat loss at this load. Plot these optimal air leakage rate points into a curve to form the corresponding relationship curve between the boiler load and the optimal air leakage rate at the furnace bottom. This curve can provide a benchmark for optimized control, enabling the boiler to maintain an optimal combustion state under different loads.

[0095] DCS (Distributed Control System) is the core system for boiler automatic control, which can monitor and adjust the boiler operation parameters in real time. Input the established load - optimal air leakage rate relationship curve into the DCS system, so that it can dynamically match the corresponding optimal air leakage rate value according to the real-time change of the unit load as the operation reference target value.

[0096] The DCS system continuously monitors the actual air leakage rate of the boiler and compares it in real time with the target value of the preset optimal air leakage rate curve. If the measured air leakage rate online deviates from the target value by more than the set threshold (e.g., ±0.5%), it indicates that the operating state of the boiler may be abnormal, such as a decrease in the bottom seal performance of the furnace, an increase in air leakage in the slag discharge system, etc. At this time, the DCS system will trigger a warning signal to prompt the operator to check and adjust the relevant operating parameters to restore to the optimal operating state, thereby improving the boiler combustion efficiency, reducing heat loss, and ensuring the safe and stable operation of the system.

[0097] Furthermore, during the test process, it is necessary to ensure stable coal quality, no soot blowing operation on the boiler, and no combustion aid facilities are put into use.

[0098] Specifically, during the test process, the stability of coal quality is crucial. Different coal types or fluctuations in coal quality will directly affect the combustion process. For example, changes in the calorific value, volatile matter, and ash content of coal will cause fluctuations in the combustion temperature and combustion efficiency, thereby interfering with the measurement data of the air flow rate and temperature in the furnace. Therefore, it is necessary to ensure that the coal type used maintains a consistent chemical composition during the test through on-line coal quality monitoring or regular chemical analysis, in order to obtain accurate and reproducible measurement results.

[0099] The soot blowing operation is usually used to remove the accumulated ash in the boiler, but this process will temporarily change the heat exchange state and combustion environment in the furnace, resulting in changes in the local temperature, air flow distribution, and flue gas composition. If soot blowing is carried out during the test, it may introduce interference factors, making the measured air volume data and flue gas temperature data unstable and affecting the accurate calculation of the air leakage rate. Therefore, ensuring no soot blowing operation during the test is to ensure the stability of the test environment and the accuracy of the data.

[0100] The input of combustion aid facilities (such as auxiliary burners or oxygen enrichment equipment) may change the air ratio and combustion conditions in the furnace, resulting in changes in the combustion process and flue gas temperature. These changes will directly affect the calculation of the total air supply volume and air leakage volume of the boiler during the measurement process, and further interfere with the evaluation of the air leakage rate. In order to ensure that the test data reflects the true state of the boiler under standard combustion conditions, it is necessary not to use any combustion aid facilities during the test process, so as to maintain the stability and consistency of the combustion conditions.

[0101] Beneficial effects: Ensuring stable coal quality, no soot blowing operation, and no input of combustion aid facilities can eliminate external interference factors during the test process, making the obtained measurement data more accurate and stable, thereby providing a reliable basis for subsequent calculation of the bottom air leakage rate and optimization of boiler operation.

[0102] Furthermore, the total air supply volume Q of the boiler is determined by the following formula:

[0103]

[0104] Where D is the average coal feeding rate, O2 is the average oxygen content at the economizer outlet, and V k is the theoretical air volume.

[0105] Specifically, the fuel mass entering the furnace per unit time is determined according to the average coal feeding rate D.

[0106] The actual excess air coefficient of the boiler under the current combustion state is estimated using the average oxygen content O2 at the economizer outlet. When O2 is large, it indicates that there is more excess air, which in turn affects the calculation of the total air supply volume.

[0107] The theoretical air volume V k represents the air volume required to completely burn 1 kg of fuel (coal). This value is usually deduced from coal quality test data, taking into account the carbon, hydrogen, sulfur, oxygen and other element contents of the coal.

[0108] After integrating the above factors and multiplying by 1000 (unit conversion), the total air supply volume Q under the current boiler operating conditions is obtained.

[0109] Based on the core principle of "coal feeding rate × excess air coefficient × theoretical air volume" and combined with unit conversion, the total air volume that the boiler air supply system should provide at a certain moment is calculated to ensure the full combustion of the fuel and the stable operation of the system.

[0110] Furthermore, the formula for calculating the theoretical air volume is:

[0111] V k = 0.0889 × (C ar + 0.375S ar ) + 0.265H ar - 0.0333O ar ,

[0112] where C ar , S ar , H ar , O ar are the carbon, sulfur, hydrogen, and oxygen contents of the as-received coal entering the furnace, respectively.

[0113] Specifically, the calculation of the theoretical air volume V k :

[0114] During the combustion process of a coal-fired boiler, the theoretical air volume refers to the air volume required to completely burn 1 kg of coal. This value depends on the content of combustible elements (such as carbon, hydrogen, sulfur, etc.) in the coal and the ratio of oxygen elements. The determination of each coefficient in the formula is derived from the balance equation of combustion chemical reactions and obtained through a large number of experiments and theoretical calculations.

[0115] Carbon (C ar ) and sulfur (S ar) Combined influence:

[0116] Both carbon and sulfur require oxygen for oxidation during combustion, but their oxygen demands are different. In the formula, (C ar + 0.375S ar ) reflects the total amount of oxygen consumed by carbon and sulfur, and the coefficient 0.0889 is the key factor for converting it into the air demand per unit volume.

[0117] Hydrogen generates water vapor during combustion, and its oxygen requirement is also different from that of carbon and sulfur. The coefficient 0.265 is used to convert the mass content of hydrogen into the corresponding air demand.

[0118] The oxygen element contained in the coal fed into the furnace will partially offset the external air demand during combustion. Therefore, when calculating the theoretical air volume, this part of the influence needs to be subtracted from the total demand. Hence, there is -0.0333O ar item.

[0119] Beneficial effects: By multiplying the contents of carbon, sulfur, hydrogen, and oxygen by the corresponding coefficients and adding or subtracting them, the theoretical air volume required for the complete combustion of coal (unit: m 3 / kg) can be obtained. This value is of great significance in boiler operation control and air ratio optimization, providing a scientific basis for accurately controlling the air supply volume, reducing the excess air coefficient, and improving the combustion efficiency.

[0120] The electronic device 200 can be an electronic device such as a desktop computer, notebook, palm computer, and cloud server. The electronic device 200 can include but is not limited to a processor 201 and a memory 202. Those skilled in the art can understand that Figure 2 These are merely examples of the electronic device 200 and do not constitute a limitation on the electronic device 200. It can include more or fewer components than shown in the figure, or combine certain components, or different components. For example, the electronic device can also include input / output devices, network access devices, buses, etc.

[0121] The processor 201 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0122] The memory 202 may be an internal storage unit of the electronic device 200. For example, it can be the hard disk or memory of the electronic device 300. The memory 202 may also be an external storage device of the electronic device 200. For example, it can be a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the electronic device 200. Further, the memory 202 may also include both the internal storage unit of the electronic device 200 and the external storage device. The memory 202 is used to store the computer program 203 and other programs and data required by the electronic device. The memory 202 can also be used to temporarily store the data that has been output or will be output.

[0123] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus / electronic device and method can be implemented in other ways. For example, the apparatus / electronic device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there may be other division methods. Multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0124] If the integrated module / unit 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, to implement all or part of the processes in the above method embodiments of this disclosure, it can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above method embodiments. The computer program may include computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0125] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present disclosure in various embodiments, and should all be included within the protection scope of the present disclosure.

Claims

1. A method for measuring the air leakage rate at the bottom of a opposed firing boiler applicable to diversified combustion, characterized in that, It includes the following steps: S1: Control the unit load to be stable and maintain the furnace negative pressure and the operating oxygen content constant; S2: Keep the coal feeding amount of the coal mill stable and control the primary air fan, the forced draft fan and the induced draft fan to be in the automatic operation mode; S3: Set an oxygen content measuring point at the outlet of the economizer, and set a primary air flow measuring point and a secondary air flow measuring point at the hot primary air main pipe and the hot secondary air main pipe at the outlet of the air preheater respectively; S4: After the unit reaches the preset load and operates stably, keep the shut-off door of the slag discharge machine fully open, continuously measure and record the primary air volume Q 11 and the secondary air volume Q 21 , close the shut-off door of the slag discharge machine. After the unit operates stably, continuously measure and record the primary air volume Q 12 and the secondary air volume Q 22 ; S5: Based on the measured air volume data, calculate the air leakage volume ΔQ at the furnace bottom = (Q 12 + Q 22 ) - (Q 11 + Q 21 ); S6: Combine the total boiler air supply volume Q and calculate the furnace bottom air leakage rate η = ΔQ / Q.

2. The measurement method according to claim 1, characterized in that, Record the primary air volume Q 11 and the secondary air volume Q 21 、Record the primary air volume Q 12 and the secondary air volume Q 22 The measurement time of both lasts for 5 minutes, data is collected every 10 seconds, and the average value is finally taken; Close the slag discharge gate shut-off door. After the unit has been operating for 30 minutes, continuously measure and record the air volume Q once 12 and the secondary air volume Q 22 .

3. The measurement method according to claim 1, characterized in that The coal quality parameters are obtained in real time through coal quality test data or the reference values of the designed coal type are adopted.

4. The measuring method according to claim 1, characterized in that It further includes the following steps: Change the furnace bottom air leakage amount ΔQ by adjusting the opening degree of the inlet air damper of the dry slag extractor, and synchronously record the flue gas temperature; Fit the relationship curve between the furnace bottom air leakage rate η and the flue gas temperature, and use the air leakage rate corresponding to the lowest point of the flue gas temperature as the optimal control value under the current load.

5. The measurement method according to claim 4, characterized in that It further includes: Repeat steps S1 - S6 for different loads to establish the corresponding relationship curve between the load and the optimal furnace bottom air leakage rate; Pre-set the curve to the boiler DCS control system, and compare the measured air leakage rate online with the curve target value in real time. When the deviation exceeds the preset threshold, an early warning is triggered.

6. The measuring method according to claim 1, characterized in that During the test process, it is necessary to ensure that the coal quality is stable, the boiler does not perform soot blowing operations and no combustion support facilities are put into use.

7. The measurement method according to claim 1, wherein The total boiler air supply volume Q is determined by the following formula: where D is the average coal feeding rate, O2 is the average oxygen content at the economizer outlet, and V k is the theoretical air volume.

8. The measuring method according to claim 1, characterized in that, The calculation formula for the theoretical air volume is: V k = 0.0889 × (C ar + 0.375S ar ) + 0.265H ar - 0.0333O ar , Among them, C ar , S ar , H ar , O ar are respectively the carbon, sulfur, hydrogen, and oxygen contents of the as-received coal fed into the furnace.

9. An electronic device, characterized in that, It includes: One or more processors; A storage unit for storing one or more programs, which when executed by the one or more processors can enable the one or more processors to implement the method for measuring the furnace bottom air leakage rate of the opposed firing boiler applicable to diversified combustion according to any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it can implement the method for measuring the furnace bottom air leakage rate of the opposed firing boiler applicable to diversified combustion according to any one of claims 1 to 8.

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