A boiler secondary air box dust accumulation prevention system and device

Abstract

The present invention relates to the field of bellows cleaning, and specifically discloses a system and device for preventing dust accumulation in a secondary bellows of a boiler. The system comprises: a secondary bellows module, an ash removal module, an anti-ash accumulation detection module, a flow control module and an ash accumulation warning module, wherein the secondary bellows module provides secondary air for the boiler; the ash removal module removes coal ash according to a wind chamber position and a preset ash removal flow rate; the anti-ash accumulation detection module monitors the working information of the dust removal module and the internal information of the secondary bellows in real time; the flow control module determines whether the ash removal module is compensated according to the primary air flow rate, determines whether the ash removal is qualified according to the coal ash distribution information, determines an adjustment method in combination with the ash removal airflow flow rate, and determines the working state of the secondary bellows; the ash accumulation warning module issues a warning when the flow control module cannot be adjusted normally, and helps to extend the cleaning cycle of the bellows and reduce maintenance costs by accurately controlling the distribution and flow rate of the ash removal airflow, while improving the overall operating efficiency and safety of the boiler.

Description

Technical Field

[0001] The invention relates to the technical field of wind box dust cleaning, and in particular to a boiler secondary wind box dust accumulation prevention system and device. Background Art

[0002] Before the secondary air enters the secondary large wind box of each layer of burner, it will exchange heat with the flue gas in the air preheater. The flue gas carries 90% of the coal ash in the coal. Due to the dust on the heating surface or internal leakage of the air preheater, the secondary air passing through the air preheater will carry some coal ash. Therefore, the coal ash carried by the secondary air will gradually settle and gather at the bottom of the wind box at low wind speed. With the continuous increase of ash accumulation, the reduction of the flow area in the wind box and the increase of wind speed, the entrained coal ash will no longer settle and reach a balance.

[0003] For example, the prior art discloses a sootblowing system for a boiler secondary wind box, comprising a sootblowing mother pipe; at least one connecting pipe arranged at intervals along the length direction of the wind box, one end of the connecting pipe being connected to the sootblowing mother pipe, and the other end extending into the wind box; a sootblowing group arranged corresponding to the connecting pipe, comprising a first sootblowing pipe and a second sootblowing pipe, the first sootblowing pipe and the second sootblowing pipe being connected to the connecting pipe and extending along the length direction of the wind box, the number of first sootblowing pipes is multiple and the multiple first sootblowing pipes are installed on the bottom wall of the wind box at intervals along the width direction of the wind box, the second sootblowing pipe is installed on the wind box and is located on the side of the first sootblowing pipe away from the bottom wall of the wind box; the first sootblowing pipe is connected to a plurality of first sootblowing parts, the second sootblowing pipe is connected to a plurality of second sootblowing parts, the multiple first sootblowing parts and the multiple second sootblowing parts are arranged at intervals along the length direction of the wind box for blowing away dust in the wind box.

[0004] There are various existing boiler secondary wind box ash removal technologies, the most common of which include mechanical vibration ash removal, in which a vibration device installed on the wind box wall strikes the wind box at a certain frequency and intensity to cause the accumulated ash to fall off under the action of vibration; there is also a technology of purging using compressed air or steam, in which purge pipes and nozzles are arranged in the wind box to spray high-pressure gas to the ash accumulation area to blow the coal ash away from the wind box; in addition, ultrasonic ash removal technology is also used, which generates sound waves of specific frequency and intensity to cause the coal ash particles to resonate under the action of the sound waves, thereby destroying their adhesion to the wall of the wind box and achieving the purpose of ash removal.

[0005] However, these technologies still have some shortcomings in practical applications. For example, mechanical vibration may cause certain damage to the bellows structure, the purge technology may have blind spots and high energy consumption, and the effect of ultrasonic dust removal may be affected by the complex environment inside the bellows. Therefore, continuous improvement and optimization are still needed to improve the efficiency and reliability of boiler secondary wind box dust removal. Summary of the invention

[0006] The purpose of the present invention is to provide a boiler secondary wind box anti-ashing system and device, which can automatically remove ash over a large area according to the working process of the boiler.

[0007] To this end, the present invention provides a boiler secondary wind box dust accumulation prevention system and device, the boiler secondary wind box dust accumulation prevention system comprises:

[0008] A secondary air box module is provided with a plurality of air chambers for providing secondary air to the boiler and providing additional oxygen to the boiler through a secondary air fan;

[0009] An ash removal module connected to the secondary air box module is used to remove the coal ash carried by the secondary air in each air chamber according to the position of each air chamber and the corresponding preset ash removal flow rate;

[0010] an anti-ash accumulation detection module, which is connected to the secondary wind box module and the ash removal module respectively, and is used to detect and monitor the gas flow rate at the outlet of each wind chamber, the primary air flow rate and the ash removal air flow rate of each wind chamber in real time during the boiler heating process, and obtain the coal ash distribution image of each wind chamber and perform preprocessing to obtain coal ash distribution information;

[0011] a flow control module, which is respectively connected to the ash removal module and the anti-ash accumulation detection module, and is used to determine whether the ash removal module needs to be compensated according to the primary air flow, to judge whether the ash removal is qualified according to all the coal ash distribution information, to determine the adjustment method of the ash removal module in combination with the ash removal air flow of each wind chamber, and to judge whether the secondary wind box is working abnormally according to the gas flow rate at the outlet of each wind chamber;

[0012] The dust accumulation warning module is connected to the flow control module and is used to send out a warning signal under the condition that the flow control module cannot be adjusted normally.

[0013] As a preferred technical solution for the boiler secondary wind box anti-ashing system, the ash removal module includes:

[0014] A dust removal air flow inlet pipe, at the outlet of which a dust removal flow control valve is provided, for diverting the primary air to obtain an initial dust removal air flow, and the initial dust removal air flow is introduced into the bottom of each air chamber of the secondary air box module;

[0015] A compensation unit, the outlet of which is arranged at the outlet of the deashing gas flow inlet pipe, for providing a compensating deashing gas flow to the initial deashing gas flow, and providing an expansion compensating gas flow during the start-up and shutdown process of the boiler;

[0016] A plurality of branch pipes are arranged at equal distances from the airflow direction of the dust removal airflow inlet pipe, and are provided with dust removal flow sub-control valves inside to disperse the dust removal airflow;

[0017] A plurality of nozzles are arranged at equal distances and opposite to each other on both sides of each branch pipe along the airflow direction of the dust removal airflow;

[0018] Wherein, the number of nozzles arranged on each branch pipe is the same.

[0019] As a preferred technical solution for the boiler secondary wind box dust accumulation prevention system, the branch pipe is divided into a first dispersed branch pipe and a second dispersed branch pipe, and the first dispersed branch pipe and the second dispersed branch pipe are arranged at intervals at the inner bottom of each wind chamber;

[0020] Wherein, the nozzles adjacent to the first dispersed branch pipe and the second dispersed branch pipe are arranged opposite to each other with a spacing.

[0021] As a preferred technical solution for the boiler secondary wind box anti-ash accumulation system, the anti-ash accumulation detection module obtains a three-dimensional distribution model of coal ash in each wind chamber, and obtains the coal ash distribution image by projecting it onto a vertical plane;

[0022] The anti-ash accumulation detection module divides each of the coal ash distribution images into a plurality of coal ash analysis areas, and calculates the chromaticity value of each of the coal ash analysis areas, which is recorded as coal ash distribution information.

[0023] As a preferred technical solution for the boiler secondary wind box anti-ashing system, the flow control module determines whether the ash removal module needs to be compensated according to the primary air flow;

[0024] If the primary air flow rate is less than the standard primary air flow rate, the flow control module determines that the dust removal module needs to be compensated;

[0025] If the primary air flow rate is greater than or equal to the standard primary air flow rate, the flow control module determines that the dust removal module does not need to be compensated.

[0026] As a preferred technical solution for the boiler secondary wind box anti-ash accumulation system, the flow control module determines the coal ash distribution uniformity characterization parameter of each wind chamber according to the coal ash distribution information;

[0027] The flow control module determines whether the corresponding wind chamber ash removal is qualified according to each of the coal ash distribution uniformity characterization parameters, and determines whether the secondary air box ash removal is qualified according to the range of each of the coal ash distribution uniformity characterization parameters.

[0028] As a preferred technical solution for the boiler secondary wind box anti-ashing system, the flow control module determines the adjustment mode of the ash removal module according to the coal ash distribution uniformity characterization parameter of the wind chamber with unqualified ash removal combined with the ash removal air flow rate.

[0029] The flow control module determines the branch pipe closest to the coal ash analysis area whose chromaticity value exceeds the average value, and increases the ash removal air flow rate in the corresponding branch pipe according to the coal ash uniformity characterization parameter;

[0030] Among them, the increase in the velocity of the ash removal airflow is positively correlated with the parameters characterizing the uniformity of the coal ash distribution.

[0031] As a preferred technical solution for the boiler secondary wind box dust accumulation prevention system, the flow control module determines whether the secondary wind box is working abnormally according to the gas flow rate at the wind chamber outlet.

[0032] If the gas flow rates at the outlets of each air chamber are within the standard secondary air flow rate range, the flow control module determines that the secondary air box operates normally;

[0033] If the gas flow rates at the outlets of each air chamber are outside the standard secondary air flow rate range, the flow control module determines that the secondary air box is operating abnormally.

[0034] As a preferred technical solution for the boiler secondary wind box anti-ash accumulation system, the ash accumulation warning module sends out the warning signal when the ash removal module needs to be compensated and the secondary wind box operates abnormally.

[0035] The present invention also provides a device for preventing dust accumulation in a secondary air box of a boiler, comprising:

[0036] The outer side wall of the secondary air box constitutes the external structure of the secondary air box and provides an installation foundation and space for the entire device;

[0037] A nearby hot primary air duct, which is used to introduce the primary air, has an inlet outside the secondary air box and an outlet inside the secondary air box;

[0038] A compensator, which is connected to the nearest hot primary air duct through a first connecting pipe, and is used to provide the compensating ash removal airflow and the expansion compensating airflow during the start-up and shutdown process of the boiler;

[0039] A main pipe, which is connected to the compensator through a second connecting pipe and is used to preliminarily disperse the dust removal airflow;

[0040] A plurality of branch pipes, including a first dispersed branch pipe and a second dispersed branch pipe, wherein the first dispersed branch pipe and the second dispersed branch pipe are arranged at equal intervals on the same side of the mother pipe, and are used to perform secondary dispersion on the initially dispersed ash removal airflow;

[0041] A plurality of nozzles are arranged at equal distances on both sides of each branch pipe to spray the secondary dispersed dust removal airflow into the wind chamber for dust removal.

[0042] The beneficial effects of the present invention are as follows: the technical solution proposes a boiler secondary wind box anti-ash accumulation system and device, which realizes real-time monitoring and effective management of coal ash distribution in the boiler secondary wind box by integrating the secondary wind box module, the ash removal module, the anti-ash accumulation detection module, the flow control module and the ash accumulation warning module. The secondary wind box module is responsible for providing secondary air to support boiler combustion, the ash removal module removes the coal ash in the wind chamber according to the preset flow rate, the anti-ash accumulation detection module obtains the three-dimensional distribution of coal ash through industrial CT scanning and performs image analysis, the flow control module adjusts the ash removal strategy according to real-time data, and the ash accumulation warning module issues an alarm when the system cannot be adjusted normally. The system is automated and accurate, can significantly improve the combustion efficiency of the boiler, reduce energy waste, and prevent potential operating risks through timely warning. In addition, by accurately controlling the distribution and flow rate of the ash removal airflow, it helps to extend the cleaning cycle of the wind box, reduce maintenance costs, and improve the overall operating efficiency and safety of the boiler, which is of great significance to ensuring the long-term stable operation of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of a boiler secondary wind box dust accumulation prevention system in an embodiment of the present invention;

[0044] Figure 2 It is a cross-sectional view of a device of a boiler secondary wind box dust accumulation prevention system in an embodiment of the present invention;

[0045] Figure 3 It is a three-dimensional internal diagram of a device of a boiler secondary wind box dust accumulation prevention system in an embodiment of the present invention;

[0046] Figure 4 The figure is a logic diagram for issuing an early warning signal in an embodiment of the present invention.

[0047] In the figure: 1, outer wall of secondary air box; 2, nearby hot primary air duct; 3, first connecting pipe; 4, compensator; 5, second connecting pipe B; 6, main pipe; 7, first dispersed branch pipe; 8, second dispersed branch pipe; 9, nozzle; 10, boiler. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0052] like Figure 1-3 As shown, this embodiment provides a boiler secondary wind box dust accumulation prevention system and device, the system comprising:

[0053] A secondary air box module is provided with a plurality of air chambers for providing secondary air to the boiler and providing additional oxygen to the boiler through a secondary air fan;

[0054] An ash removal module connected to the secondary air box module is used to remove the coal ash carried by the secondary air in each air chamber according to the position of each air chamber and the corresponding preset ash removal flow rate;

[0055] an anti-ash accumulation detection module, which is connected to the secondary wind box module and the ash removal module respectively, and is used to detect and monitor the gas flow rate at the outlet of each wind chamber, the primary air flow rate and the ash removal air flow rate of each wind chamber in real time during the boiler heating process, and obtain the coal ash distribution image of each wind chamber and perform preprocessing to obtain coal ash distribution information;

[0056] a flow control module, which is respectively connected to the ash removal module and the anti-ash accumulation detection module, and is used to determine whether the ash removal module needs to be compensated according to the primary air flow, to judge whether the ash removal is qualified according to all the coal ash distribution information, to determine the adjustment mode of the ash removal module in combination with the ash removal airflow of each wind chamber, and to judge whether the secondary wind box is working abnormally according to the gas flow rate at the outlet of each wind chamber;

[0057] The dust accumulation warning module is connected to the flow control module and is used to send out a warning signal under the condition that the flow control module cannot be adjusted normally.

[0058] In this implementation, for a thermal power plant, the coal mill first grinds the coal into fine coal powder for easy combustion, which is then mixed with primary air at a temperature of 350°C to form a coal-rich airflow that is sent to the boiler for combustion. The primary air not only carries the coal powder, but also helps the ignition and combustion of the coal powder due to its high temperature. During the combustion process, in order to ensure that the coal powder can be fully burned, additional secondary air is sent to the boiler to provide the necessary oxygen. The secondary air box inside the boiler is responsible for evenly distributing these secondary air to support the uniformity and sufficiency of the combustion process.

[0059] As the core of the power plant, the boiler converts the heat generated by the combustion of pulverized coal into steam to drive the turbine to generate electricity. The flue gas produced after combustion contains incompletely burned particulate matter and harmful gases. After leaving the boiler, these flue gases first pass through the air preheater, where the heat in the flue gas is used to preheat the primary and secondary air that will enter the boiler. This process significantly improves the thermal efficiency of the boiler. On the other side of the air preheater, the cold air exchanges heat with the hot air, and is preheated and sent to the boiler. After passing through the air preheater, the flue gas is discharged into the atmosphere through the chimney, while the preheated air continues to participate in the combustion process in the boiler.

[0060] In the above embodiment, the number of air chambers included in the secondary air box module is preferably 6 or 10; the flow rate of the gas is detected by a flow meter, which is a prior art and is not specifically limited.

[0061] In detail, the dust removal module includes:

[0062] A dust removal air flow inlet pipe, at the outlet of which a dust removal flow control valve is provided, for diverting the primary air to obtain an initial dust removal air flow, and the initial dust removal air flow is introduced into the bottom of each air chamber of the secondary air box module;

[0063] A compensation unit, the outlet of which is arranged at the outlet of the deashing gas flow inlet pipe, for providing a compensating deashing gas flow to the initial deashing gas flow, and providing an expansion compensating gas flow during the start-up and shutdown process of the boiler;

[0064] A plurality of branch pipes are arranged at equal distances from the airflow direction of the dust removal airflow inlet pipe, and are provided with dust removal flow sub-control valves inside to disperse the dust removal airflow;

[0065] A plurality of nozzles are arranged at equal distances and opposite to each other on both sides of each branch pipe along the airflow direction of the dust removal airflow;

[0066] Wherein, the number of nozzles arranged on each branch pipe is the same.

[0067] In this embodiment, the ash removal airflow is a mixed airflow of the initial ash removal airflow and the compensation ash removal airflow, or the initial airflow after the excess airflow is removed by the compensation unit, or it is only the initial ash removal airflow.

[0068] In detail, the number of branches contained in a single wind chamber is not less than 4, and the number of nozzles in a single branch is not less than 18, that is, the number of nozzles on a single side of the branch is not less than 9; the nozzle is a conical nozzle, and its shape is not specifically limited, as long as it can reduce the diameter of the discharged airflow.

[0069] It is understandable that the branch pipe subdivides the dust removal airflow, so that the dust removal airflow can reach every corner of the secondary air box more accurately, improving the dust prevention effect. The conical design of the nozzle allows the dust removal airflow to be ejected at a specific angle and speed to form an effective purge airflow. In addition, through this change in pipe diameter, the flow rate of the diversion can be increased when the flow rate of the air supply port is fixed, thereby enhancing the purge force on the dust accumulation.

[0070] In detail, the branch pipe is divided into a first dispersed branch pipe and a second dispersed branch pipe, and the first dispersed branch pipe and the second dispersed branch pipe are arranged at intervals at the inner bottom of each of the wind chambers;

[0071] Wherein, the nozzles adjacent to the first dispersed branch pipe and the second dispersed branch pipe are arranged opposite to each other with a gap.

[0072] It is understandable that the staggered design of the nozzles of the first and second dispersed branches has significant advantages in the secondary wind box anti-ash accumulation system. This layout can ensure that the airflow is evenly distributed in the wind box, effectively disturb the flow field, and prevent dust from depositing at the bottom of the wind box. The staggered nozzle design enables the airflow to impact the ash layer from different angles and directions, promote the resuspension and distribution of dust, and thus reduce the formation of ash accumulation. In addition, this design helps to improve combustion efficiency because it can deliver oxygen to the combustion area more evenly, ensuring the full combustion of coal powder. At the same time, the uniform airflow distribution also helps to reduce the dead zone inside the wind box, improve the heat transfer efficiency of the wind box, and extend the cleaning cycle of the wind box, reducing maintenance requirements, while also helping to improve the overall operating efficiency and safety of the boiler.

[0073] In detail, the anti-ash accumulation detection module obtains a three-dimensional distribution model of coal ash in each wind chamber, and obtains the coal ash distribution image by projecting it onto a vertical plane;

[0074] The anti-ash accumulation detection module divides each of the coal ash distribution images into a plurality of coal ash analysis areas, and calculates the chromaticity value of each of the coal ash analysis areas, which is recorded as coal ash distribution information.

[0075] In this embodiment, an industrial CT scanner (computed tomography) is used to obtain a three-dimensional distribution model of the coal ash in each wind chamber. This is a prior art and will not be described in detail.

[0076] In the above embodiment, the coal ash distribution image of each wind chamber is segmented in the same manner, the area and shape of each coal ash analysis area are the same, and the number of coal ash analysis areas of a single coal ash distribution image is preferably 49. During the pretreatment process, the higher the coal ash concentration, the greater the chromaticity value. Generally speaking, pure secondary air may be close to colorless and transparent under normal circumstances, and its chromaticity value is low and relatively stable. As coal ash is mixed and accumulated, the color of the air will change, and the chromaticity value will change accordingly. In practice, an increase in coal ash content may cause the air to appear gray, resulting in an increase in chromaticity value.

[0077] The three-dimensional distribution model of coal ash is projected and superimposed to obtain an image, which can more simply and clearly obtain the distribution of coal ash in the wind chamber, facilitating subsequent analysis.

[0078] It is understandable that, similar to CT scanning in medicine, industrial CT scanners perform multi-angle X-ray irradiation around the bellows. When X-rays pass through the bellows, they will produce attenuation signals of different intensities due to the different absorption of X-rays by different materials in the bellows (such as metal bellows walls, air, coal ash, etc.). The scanner receives these attenuation signals and reconstructs a three-dimensional image of the inside of the bellows through a computer algorithm, clearly showing the distribution and density of coal ash in the three-dimensional space of the bellows.

[0079] The use of industrial CT scanning technology combined with the method of coal ash distribution image analysis can provide a clear image of the three-dimensional distribution of coal ash inside the bellows, which helps to intuitively identify and locate the ash accumulation area, thereby accurately guiding the ash removal work; by projecting and dividing the three-dimensional model into uniform analysis areas, the uniformity of the coal ash distribution can be quantified, and the analysis of the chromaticity value provides an objective measurement indicator for the coal ash concentration, which is convenient for monitoring and comparing the coal ash content in different areas, and timely discovering problems in the ash removal process.

[0080] In detail, the flow control module determines whether the dust removal module needs to be compensated according to the primary air flow; if the primary air flow is less than the standard primary air flow, the flow control module determines that the dust removal module needs to be compensated;

[0081] If the primary air flow rate is greater than or equal to the standard primary air flow rate, the flow control module determines that the dust removal module does not need to be compensated.

[0082] In practice, the standard primary air flow rate is determined based on the average primary air flow rate of the normal operation of the boiler system and the normal boiler coal powder delivery in the historical records. In the case where the primary air flow rate is too large and affects the normal circulation of the secondary air in the secondary wind box, the primary air can be separated by the compensation unit to reduce the primary air flow rate entering the ash removal module. The compensation amount is the air flow rate to reach the preset ash removal flow rate, and the preset ash removal flow rate is the minimum ash removal air flow rate when the boiler operates normally and there is no ash accumulation during the historical boiler operation process.

[0083] In detail, the flow control module determines the coal ash distribution uniformity characterization parameter of each wind chamber according to the coal ash distribution information;

[0084] The flow control module determines whether the corresponding wind chamber ash removal is qualified according to each of the coal ash distribution uniformity characterization parameters, and determines whether the secondary air box ash removal is qualified according to the range of each of the coal ash distribution uniformity characterization parameters.

[0085] In the implementation, the coal ash distribution uniformity characterization parameter is determined based on the average deviation of the chromaticity value of the coal ash analysis area in the single coal ash distribution image and the corresponding average value. If the coal ash distribution uniformity characterization parameter is greater than the standard coal ash distribution uniformity parameter, the corresponding wind chamber ash removal is judged to be unqualified. The standard distribution uniformity parameter is selected in the interval [0.2, 0.3];

[0086] If the extreme values ​​of the parameters characterizing the uniform distribution of coal ash exceed the interval [0.1, 0.15], the ash removal of the secondary air box is unqualified.

[0087] It is understandable that when the parameter characterizing the uniformity of ash distribution exceeds this interval, it means that there is a large deviation in the ash distribution, and the ash removal in the wind chamber is unqualified, which will affect the performance of the secondary wind box. When the extreme difference exceeds this interval, it means that the ash distribution uniformity between different wind chambers of the secondary wind box is too different, and the overall ash removal effect is not good, which will have an adverse effect on the safety, energy saving, and efficient operation of the boiler. Therefore, using this interval as the basis for judging whether the ash removal of the secondary wind box is qualified can effectively ensure the stable operation and performance optimization of the system.

[0088] In detail, the flow control module determines the adjustment mode of the ash removal module according to the coal ash distribution uniformity characterization parameter of the wind chamber with unqualified ash removal combined with the ash removal air flow rate,

[0089] The flow control module determines the branch pipe closest to the coal ash analysis area whose chromaticity value exceeds the average value, and increases the ash removal air flow rate in the corresponding branch pipe according to the coal ash uniformity characterization parameter;

[0090] Among them, the increase in the velocity of the ash removal airflow is positively correlated with the parameters characterizing the uniformity of the coal ash distribution.

[0091] In practice, by reducing the opening of the ash removal flow sub-control valve to increase the corresponding ash removal airflow velocity, it can be understood that according to the Bernoulli principle, in the stable flow of the fluid, there is a certain relationship between the flow velocity and the pressure, that is, the greater the flow velocity, the lower the pressure. In this case, when the original air supply port flow velocity is fixed, and the diversion from here passes through the smaller valve port, the cross-sectional area of ​​the valve port becomes smaller. According to the continuity equation Q = A × v, where Q is the flow rate, A is the cross-sectional area, and v is the flow rate, under the premise that the flow rate remains basically unchanged (ignoring a small amount of energy loss), the cross-sectional area A of the valve port decreases, which will inevitably lead to an increase in the flow rate v.

[0092] In this embodiment, the increase in the ash removal airflow velocity is determined based on the product of the difference between the coal ash distribution uniformity characterization parameter and the coal ash distribution uniformity parameter, and the sub-flow of the ash removal airflow in the corresponding branch pipe. The sub-flow of the ash removal airflow in the corresponding branch pipe is determined based on the ratio of the ash removal airflow to the total number of branches in the current air chamber.

[0093] Specifically, the flow control module determines whether the secondary air box is working abnormally according to the gas flow rate at the air chamber outlet.

[0094] If the gas flow rates at the outlets of each air chamber are within the standard secondary air flow rate range, the flow control module determines that the secondary air box operates normally;

[0095] If the gas flow rates at the outlets of each air chamber are outside the standard secondary air flow rate range, the flow control module determines that the secondary air box is operating abnormally.

[0096] In this embodiment, the standard secondary air flow rate range is determined based on 0.9 to 1.1 times the average value of the gas flow rate at the wind chamber outlet during normal operation of the boiler in historical data.

[0097] It is understandable that at the point where the wind box is connected to the burner, the airflow needs to be distributed and delivered according to the requirements of the burner. The flow field will change significantly here, and the flow rate will be adjusted according to the design and operation requirements of the burner to form a specific velocity and pressure distribution to ensure that each burner can obtain the same air volume and wind speed to ensure the full combustion of the pulverized coal.

[0098] See also Figure 4 As shown, it is a logic diagram of issuing a warning signal in an embodiment of the present invention. The dust accumulation warning module issues the warning signal when the dust removal module needs to be compensated and the secondary air box operates abnormally.

[0099] It is understandable that problems with the primary or secondary fans will directly affect the air supply. For example, fan blade wear, corrosion or dust accumulation will reduce the fan's efficiency and air output capacity. When the primary fan air volume is insufficient, it is naturally difficult to provide excess flow; secondary fan failure will cause the secondary air to be unable to enter the wind box and furnace at normal pressure and flow, thereby affecting the heating effect and causing abnormal heating.

[0100] Dust accumulation, scaling or blockage by foreign matter inside the air duct will increase the resistance of the air duct and reduce the flow of primary or secondary air. For primary air, it will be unable to meet the normal transportation and combustion needs without excess flow; for secondary air, the reduced flow will affect its mixing and combustion heating process in the furnace. In addition, if there is a leak in the air duct, part of the air volume will leak out, reducing the effective air volume, which will also cause the above problems. Especially in the case of severe leakage, the heating stability of the secondary air will be greatly affected.

[0101] When the boiler load suddenly increases significantly, the amount of fuel increases accordingly, and the demand for primary air delivery rises sharply, which may exhaust the remaining primary air in an instant. At the same time, in order to maintain stable combustion, the secondary air also needs to be adjusted quickly, but due to the response speed limitation of the system or the problem of the regulating device, it is impossible to provide enough secondary air in time for good heating and combustion support, resulting in abnormal secondary air heating. On the contrary, when the boiler load is greatly reduced, if the adjustment is improper, a similar situation may occur, the flow distribution of the primary air will become unreasonable, and the heating of the secondary air will be difficult to meet the new working conditions.

[0102] If there are problems with heat exchange equipment such as air preheaters, such as reduced heat transfer area, reduced heat transfer efficiency, or internal leakage, the temperature and flow of primary and secondary air will be affected. After passing through the heat exchanger, the primary air cannot obtain enough heat to increase the temperature and momentum, resulting in insufficient air volume and no excess flow. For secondary air, heat exchanger failure prevents it from reaching the expected heating temperature, and then after entering the furnace, it cannot effectively participate in combustion and heating, causing abnormalities in the heating process and affecting the overall operating efficiency and stability of the boiler.

[0103] Therefore, when both of the flow control module's judgment results are abnormal at the same time, it means that the flow control module cannot perform autonomous adjustments and the entire system cannot work normally, and manual intervention is required to eliminate the cause of the abnormality, so an early warning message needs to be issued.

[0104] The present invention also provides a device for a boiler secondary wind box dust accumulation prevention system, comprising:

[0105] The outer side wall 1 of the secondary air box constitutes the external structure of the secondary air box and provides an installation foundation and space for the entire device;

[0106] A nearby hot primary air duct 2, which is used to introduce the primary air, with its inlet outside the secondary air box and its outlet inside the secondary air box;

[0107] The compensator 4 is connected to the nearest hot primary air duct through the first connecting pipe 3 to provide the compensating ash removal airflow and the expansion compensating airflow during the start-up and shutdown process of the boiler 10;

[0108] A main pipe 6, which is connected to the compensator through a second connecting pipe 5, and is used to preliminarily disperse the ash removal airflow;

[0109] A plurality of branch pipes, including a first dispersion branch pipe 7 and a second dispersion branch pipe 8, the first dispersion branch pipe and the second dispersion branch pipe are equidistantly arranged on the same side of the mother pipe, for secondary dispersion of the initially dispersed ash removal airflow;

[0110] A plurality of nozzles 9 are arranged at equal distances on both sides of each branch pipe to spray the secondary dispersed ash removal airflow into the wind chamber for ash removal.

[0111] In this embodiment, the first connecting pipe plays the role of transmitting the primary air, and its material has good heat resistance and sealing properties, ensuring that the primary air does not leak during the transmission process and the heat loss is small.

Claims

1. A boiler secondary wind box dust accumulation prevention system, characterized in that: include: A secondary air box module is provided with a plurality of air chambers for providing secondary air to the boiler and providing additional oxygen to the boiler through a secondary air fan; An ash removal module connected to the secondary air box module is used to remove the coal ash carried by the secondary air in each air chamber according to the position of each air chamber and the corresponding preset ash removal flow rate; an anti-ash accumulation detection module, which is connected to the secondary wind box module and the ash removal module respectively, and is used to detect and monitor the gas flow rate at the outlet of each wind chamber, the primary air flow rate and the ash removal air flow rate of each wind chamber in real time during the boiler heating process, and obtain the coal ash distribution image of each wind chamber and perform preprocessing to obtain coal ash distribution information; a flow control module, which is respectively connected to the ash removal module and the anti-ash accumulation detection module, and is used to determine whether the ash removal module needs to be compensated according to the primary air flow, to judge whether the ash removal is qualified according to all the coal ash distribution information, to determine the adjustment method of the ash removal module in combination with the ash removal air flow of each wind chamber, and to judge whether the secondary wind box is working abnormally according to the gas flow rate at the outlet of each wind chamber; The dust accumulation warning module is connected to the flow control module and is used to send out a warning signal under the condition that the flow control module cannot be adjusted normally.

2. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The dust removal module comprises: A dust removal air flow inlet pipe, at the outlet of which a dust removal flow control valve is provided, for diverting the primary air to obtain an initial dust removal air flow, and the initial dust removal air flow is introduced into the bottom of each air chamber of the secondary air box module; A compensation unit, the outlet of which is arranged at the outlet of the deashing gas flow inlet pipe, for providing a compensating deashing gas flow to the initial deashing gas flow, and providing an expansion compensating gas flow during the start-up and shutdown process of the boiler; A plurality of branch pipes are arranged at equal distances from the airflow direction of the dust removal airflow inlet pipe, and are provided with dust removal flow sub-control valves inside to disperse the dust removal airflow; A plurality of nozzles are arranged at equal distances and opposite to each other on both sides of each branch pipe along the airflow direction of the dust removal airflow; Wherein, the number of nozzles arranged on each branch pipe is the same.

3. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The branch pipe is divided into a first dispersed branch pipe and a second dispersed branch pipe, and the first dispersed branch pipe and the second dispersed branch pipe are arranged at intervals at the inner bottom of each wind chamber; Wherein, the nozzles adjacent to the first dispersed branch pipe and the second dispersed branch pipe are arranged opposite to each other with a gap.

4. The boiler secondary wind box dust accumulation prevention system according to claim 3, characterized in that: The anti-ash accumulation detection module obtains a three-dimensional distribution model of coal ash in each wind chamber, and obtains the coal ash distribution image by projecting it onto a vertical plane; The anti-ash accumulation detection module divides each of the coal ash distribution images into a plurality of coal ash analysis areas, and calculates the chromaticity value of each of the coal ash analysis areas, which is recorded as coal ash distribution information.

5. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The flow control module determines whether the dust removal module needs to be compensated according to the primary air flow; If the primary air flow rate is less than the standard primary air flow rate, the flow control module determines that the dust removal module needs to be compensated; If the primary air flow rate is greater than or equal to the standard primary air flow rate, the flow control module determines that the dust removal module does not need to be compensated.

6. The boiler secondary wind box dust accumulation prevention system according to claim 5, characterized in that: The flow control module determines the coal ash distribution uniformity characterization parameter of each wind chamber according to the coal ash distribution information; The flow control module determines whether the corresponding wind chamber ash removal is qualified according to each of the coal ash distribution uniformity characterization parameters, and determines whether the secondary air box ash removal is qualified according to the range of each of the coal ash distribution uniformity characterization parameters.

7. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The flow control module determines the adjustment mode of the ash removal module according to the coal ash distribution uniformity characterization parameter of the wind chamber with unqualified ash removal combined with the ash removal air flow rate. The flow control module determines the branch pipe closest to the coal ash analysis area whose chromaticity value exceeds the average value, and increases the ash removal air flow rate in the corresponding branch pipe according to the coal ash uniformity characterization parameter; Among them, the increase in the velocity of the ash removal airflow is positively correlated with the parameters characterizing the uniformity of the coal ash distribution.

8. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The flow control module determines whether the secondary air box is working abnormally according to the gas flow rate at the air chamber outlet. If the gas flow rates at the outlets of each air chamber are within the standard secondary air flow rate range, the flow control module determines that the secondary air box operates normally; If the gas flow rates at the outlets of each air chamber are outside the standard secondary air flow rate range, the flow control module determines that the secondary air box is operating abnormally.

9. The boiler secondary wind box dust accumulation prevention system according to claim 1, characterized in that: The dust accumulation warning module sends out the warning signal when the dust removal module needs to be compensated and the secondary air box operates abnormally.

10. A device applied to the boiler secondary wind box dust accumulation prevention system according to any one of claims 1 to 9, characterized in that: include: The outer side wall of the secondary air box constitutes the external structure of the secondary air box and provides an installation foundation and space for the entire device; A nearby hot primary air duct, which is used to introduce the primary air, has an inlet outside the secondary air box and an outlet inside the secondary air box; A compensator, which is connected to the nearest hot primary air duct through a first connecting pipe, and is used to provide the compensating ash removal airflow and the expansion compensating airflow during the start-up and shutdown process of the boiler; A main pipe, which is connected to the compensator through a second connecting pipe and is used to preliminarily disperse the dust removal airflow; A plurality of branch pipes, including a first dispersed branch pipe and a second dispersed branch pipe, wherein the first dispersed branch pipe and the second dispersed branch pipe are arranged at equal intervals on the same side of the mother pipe, and are used to perform secondary dispersion on the initially dispersed ash removal airflow; A plurality of nozzles are arranged at equal distances on both sides of each branch pipe to spray the secondary dispersed dust removal airflow into the wind chamber for dust removal.

Images