Method and device for stabilizing combustion by means of acoustic waves and pulverized coal burner

Abstract

The application discloses a method and device for stabilizing combustion by using sound waves and a pulverized coal burner. The method for stabilizing combustion by using sound waves improves the distribution of the pulverized coal in a furnace by applying a sound field fluctuation in the furnace and uses fluid vibration and disturbance caused by the sound waves to optimize the mixing process of the pulverized coal and control the combustion process. The method can make the distribution of the pulverized coal more uniform and the heat release rate more stable, thereby effectively realizing stable combustion under low load without increasing additional fuel or cost.

Description

Technical Field

[0001] This invention relates to coal-fired boilers, and more specifically to a method, apparatus, and pulverized coal burner for stable combustion using sound waves. Background Technology

[0002] The proportion of renewable energy sources such as wind and solar power in the energy mix is ​​increasing year by year. However, the intermittent and unpredictable nature of renewable energy means that thermal power plants often need to operate under low-load conditions to ensure grid stability. Yet, coal-fired boilers often experience unstable combustion under low-load conditions. Uneven mixing of pulverized coal and air leads to increased pressure fluctuations within the furnace, which can even cause flameout in severe cases, seriously affecting the normal operation of the boiler. Furthermore, unstable combustion also reduces combustion efficiency and increases pollutant content in emissions, impacting not only the economics of coal-fired boilers but also posing a threat to environmental protection.

[0003] Traditional solutions improve combustion stability by adding fuel oil or oxygen to aid combustion, but these methods increase operating costs and have a significant environmental impact. Furthermore, these methods often require extensive modifications to existing equipment, which are technically challenging and costly, leading to increased operating and maintenance costs and additional technical and economic burdens. The high cost of using fuel oil or oxygen also reduces the economic efficiency of coal-fired power plants.

[0004] Therefore, a new pulverized coal combustion stability scheme is needed, which can improve combustion stability under low load operation without increasing additional fuel input, while also taking into account economy and environmental protection. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to address the problems of unstable combustion, large fluctuations in furnace pressure, and low combustion efficiency in coal-fired boilers operating at low loads. It provides a method, device, and pulverized coal burner that utilizes sound waves to stabilize combustion, thereby actively controlling the combustion process and improving the stability of pulverized coal combustion under low loads.

[0006] Technical solution: The method for stabilizing combustion using sound waves described in this invention includes: introducing sound waves of a specific frequency and amplitude into the furnace, whereby the sound waves generate sound field pulsations, causing vibration and disturbance of the fluid in the furnace, improving the uniformity of mixing of pulverized coal and air, and promoting the combustion reaction.

[0007] Furthermore, the frequency, amplitude, and duration of the sound waves are dynamically adjusted based on the operating data of the coal-fired boiler to achieve precise control of the pulverized coal combustion process; the operating data includes boiler load changes, furnace temperature, pressure fluctuations, and pulverized coal flow rate.

[0008] The following mathematical relationship exists between acoustic pulsation parameters and furnace pressure fluctuations:

[0009] P(t) = P0 sin(ωt + φ)

[0010] P 声 (t)=Asin(ωt+φ+π)

[0011] Where P(t) is the furnace pressure fluctuation at time t, P 声 (t) is the sound wave pressure fluctuation at time t, P0 is the amplitude of the pressure fluctuation, and A is the amplitude of the sound wave.

[0012] The device for stable combustion using sound waves according to the present invention includes a sound wave generating device, a control unit, and a sound wave transmission structure. The control unit is used to control the sound wave generating device to generate sound waves with a specific frequency and amplitude, and the sound wave transmission structure is used to introduce the sound waves into the furnace and distribute them evenly in the furnace.

[0013] Furthermore, the control unit is also used to receive operating data of the coal-fired boiler and dynamically adjust the frequency, amplitude and duration of the sound waves generated by the sound wave generator according to the operating data, so as to achieve precise control of the pulverized coal combustion process; the operating data includes boiler load changes, furnace temperature, pressure fluctuations and pulverized coal flow rate.

[0014] Furthermore, the sound wave generating device uses a high-performance piezoelectric ceramic sheet as a vibration source.

[0015] Furthermore, the sound wave transmission structure includes a sound wave guide, a reflector, and a loudspeaker. The sound wave guide adopts a streamlined design to reduce energy loss during sound wave propagation. The reflector is used to reflect sound waves to key areas inside the furnace, enhancing the mixing of pulverized coal and air. The loudspeaker is used to enhance the amplitude and coverage of the sound waves, improving the optimization effect of sound waves on the combustion process.

[0016] Furthermore, an acoustic isolation layer is set on key components of the acoustic wave transmission path, and the acoustic isolation layer is made of acoustic wave attenuation material.

[0017] Furthermore, the sound wave generating device is installed at the primary air nozzle of the coal-fired boiler without affecting the normal output of the primary air.

[0018] Furthermore, the control unit also has monitoring and alarm functions, and can promptly issue warnings to operators when abnormal operation of the coal-fired boiler or impending malfunction is detected.

[0019] The pulverized coal burner of the present invention includes the device for stabilizing combustion using sound waves.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) It improves the combustion stability of coal-fired boilers when operating at low and ultra-low loads, and reduces furnace pressure fluctuations and the risk of flameout;

[0022] (2) It improves the combustion efficiency of pulverized coal and reduces energy consumption and emissions of harmful substances such as nitrogen oxides and particulate matter;

[0023] (3) It reduces the dependence of coal-fired boilers on fuel oil and oxygen, simplifies boiler modification, and reduces operating and maintenance costs;

[0024] In summary, this invention addresses the low-load and ultra-low-load operating conditions of coal-fired boilers by applying acoustic pulsations within the furnace. Utilizing the hydrodynamic effects induced by these acoustic waves, it improves the distribution of pulverized coal and the combustion process within the furnace, achieving proactive optimization and control of the combustion process. This enhances the stability of pulverized coal combustion and enables efficient and environmentally friendly operation of the coal-fired boiler. This invention is simple to implement, low-cost, and improves boiler operating efficiency and safety. It is applicable to coal-fired boilers of various sizes and has broad application prospects and significant economic benefits. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device for stabilizing combustion using sound waves provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram illustrating the principle of controlling a flame using sound waves in an embodiment of the present invention. Detailed Implementation

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] The core idea of ​​this invention lies in using sound waves to regulate the combustion environment. By applying sound waves of specific frequency and intensity to the furnace, the combustion process is controlled, thus solving the problem of combustion instability during low-load operation. This invention provides an economical and effective solution that supports the thermal power industry in maintaining operational flexibility and stability during the energy structure transformation as the proportion of renewable energy continues to increase.

[0029] Combination Figure 1 This invention provides a method for stable combustion using sound waves, comprising: introducing sound waves 3 of a specific frequency and amplitude into the furnace; the sound waves 3 generating sound field pulsations within the furnace; and utilizing the principle of interaction between sound waves and fluids, namely the energy transfer and momentum exchange of sound waves, causing vibration and disturbance 4 of the fluid within the furnace, thereby improving the mixing uniformity of pulverized coal and air and promoting the combustion reaction. The frequency, amplitude, and duration of the sound waves are dynamically adjusted based on the operating data of the coal-fired boiler to achieve precise control of the pulverized coal combustion process. The operating data includes boiler load changes, furnace temperature, pressure fluctuations, and pulverized coal flow rate.

[0030] The acoustic combustion stabilization method provided in this invention is based on the principle of sound wave-fluid interaction. By precisely controlling the sound wave parameters, it achieves active optimization control of the pulverized coal combustion process. When sound waves propagate in the furnace, they generate sound field pulsations, which can cause vibration and disturbance of the fluid in the furnace. These vibrations and disturbances not only improve the uniformity of pulverized coal and air mixing but also promote mass and heat transfer during combustion, thereby improving combustion stability and efficiency.

[0031] Combination Figure 1 and Figure 2 This invention also provides a device for stable combustion using sound waves, including a sound wave generator 2, a control unit 5, and a sound wave transmission structure. The sound wave generator 2 generates stable and controllable sound waves 3. The control unit 5 receives real-time operating data 6 of the boiler unit, including boiler load changes, furnace temperature, pressure fluctuations, and pulverized coal flow. When the control unit 5 detects a decrease in pulverized coal flow and a decrease in furnace temperature, it indicates a low-load combustion state. If, under this low-load combustion state, the furnace pressure fluctuation exceeds a set value, such as 15%, combustion instability is considered to have occurred. The control unit 5 determines the optimal sound wave pulsation parameters for the current state and dynamically adjusts the sound wave generator 2, including precise control of the sound wave frequency, amplitude, and duration, to achieve precise control of the pulverized coal combustion process. The sound wave pulsation parameters and furnace pressure fluctuations have the following mathematical relationship:

[0032] P(t) = P0 sin(ωt + φ)

[0033] P 声 (t)=Asin(ωtt+φ+π)

[0034] Where P(t) is the furnace pressure fluctuation at time t, P 声 (t) is the sound wave pressure fluctuation at time t, P0 is the amplitude of the pressure fluctuation; A is the amplitude of the sound wave, which is related to the selection of the sound wave generator 2 and the model of the boiler unit.

[0035] The acoustic wave transmission structure is used to introduce acoustic waves into the furnace and distribute them uniformly within it, allowing them to interact with the pulverized coal flame. The design of the acoustic wave generator 2 must consider the specific structure and operating characteristics of the coal-fired boiler, including the shape and size of the furnace and the location of the pulverized coal nozzles, to ensure that the acoustic waves can generate effective acoustic field pulsations within the furnace and interact well with the pulverized coal flame. The design of the acoustic wave transmission structure must also consider the propagation characteristics of the acoustic waves and the flow field distribution within the furnace to enhance the propagation effect and uniformity of the acoustic waves within the furnace.

[0036] In terms of the design of the acoustic wave generator 2, a high-power output and stable performance acoustic wave generator is selected to ensure the generation of sound waves with sufficient amplitude. A high-performance piezoelectric ceramic sheet can be used as the vibration source, possessing excellent mechanical strength and piezoelectric properties. The acoustic wave generator 2 has a wide range of vibration frequencies and amplitudes to meet the combustion requirements under different load conditions. The acoustic wave driver is manufactured using precision machining technology to ensure stable sound wave transmission. The acoustic wave transmission pipe is made of high-temperature and corrosion-resistant materials to adapt to the high-temperature and high-humidity environment inside the furnace. Furthermore, the acoustic wave generator 2 is equipped with temperature and pressure sensors to monitor its operating status in real time and ensure long-term stable operation. Regarding the installation of the acoustic wave generator 2, it is installed at the primary air nozzle 1 of the coal-fired boiler without affecting the normal output of primary air.

[0037] In terms of optimizing the sound wave transmission structure, components such as sound waveguides, reflectors, and amplifiers are used to ensure that sound waves are evenly distributed within the furnace. The sound waveguides feature a streamlined design to reduce energy loss during propagation. Reflectors are used to reflect sound waves to key areas within the furnace, enhancing the mixing of pulverized coal and air. Amplifiers are used to increase the amplitude and coverage of the sound waves, improving their optimization effect on the combustion process.

[0038] In addition, to prevent sound waves from affecting the safety of the boiler structure, sound wave safety protection measures are implemented. Specifically, sound wave isolation layers are installed on key components along the sound wave transmission path. These isolation layers use sound wave attenuation materials to reduce the potential damage to the boiler structure caused by sound waves. Simultaneously, the sound wave generating device and control unit are regularly inspected and maintained to ensure their long-term stable operation.

[0039] Control unit 5 has the following functions:

[0040] (1) Real-time data acquisition: During the operation of the coal-fired boiler, the operating data of the boiler unit is collected in real time, including boiler load changes, furnace temperature, pressure fluctuations, pulverized coal flow fluctuations, etc., and these operating data are transmitted to the control unit 5.

[0041] (2) Data processing and analysis: When the control unit 5 detects that the coal powder flow rate of the boiler unit decreases and the furnace temperature decreases, it is a low-load combustion state. If the furnace pressure fluctuation exceeds the upper limit of 15% under this low-load combustion state (the upper limit of 15% can be adjusted according to different boiler units), it is considered that the combustion is unstable and the parameters of the sound wave generator 2 need to be adjusted.

[0042] (3) Parameter adjustment: The control unit 5 uses the built-in algorithm model (using existing neural network models, such as multilayer perceptron (MLP) or other applicable neural network models) to analyze and process the furnace pressure pulsation data, determine the appropriate acoustic pulsation parameters, and then send adjustment commands to the acoustic wave generator 2 to achieve precise control of acoustic wave frequency, amplitude and duration, thereby achieving precise active regulation of the combustion process.

[0043] (4) Monitoring and Alarm: The control unit 5 also has monitoring and alarm functions. When an abnormal operating status of the coal-fired boiler is detected or a fault is about to occur, it can promptly issue a warning to the operator so that timely measures can be taken to deal with the situation.

[0044] This invention also provides a pulverized coal burner, including the device for stabilizing combustion using sound waves described in this invention.

[0045] This invention utilizes the technical principle of actively controlling the combustion process using sound waves, and is mainly based on the following points:

[0046] Acoustic field pulsation improves mixing uniformity: Utilizing the principle of interaction between sound waves and fluids—namely, the energy transfer and momentum exchange of sound waves—vibrations and disturbances occur in the fluid within the furnace. The flow field pulsation at the primary air nozzle increases the contact area and mixing opportunities between air and pulverized coal, thereby improving the uniformity of the mixing between pulverized coal and air ejected from the primary air nozzle. Improved mixing uniformity helps to improve the combustion process, reduce localized overheating or underburning, and increase combustion efficiency.

[0047] The flow field pulsation caused by acoustic field pulsation helps stabilize the flame within the furnace. This pulsation suppresses flame fluctuations and oscillations, reducing pressure fluctuations within the furnace. Simultaneously, it enhances flame rigidity and stability, reducing the risk of flameout.

[0048] Active control optimizes the combustion process: The control unit analyzes and processes sensor data in real time, accurately determining the current combustion state and automatically adjusting the parameters of the acoustic wave generator. It can optimize the combustion process in real time based on factors such as load changes, achieving stable combustion and efficient operation under low loads.

Claims

1. A method for flame stabilization using acoustic waves, characterized by, The application relates to a device for stabilizing combustion of a coal-fired boiler by using sound waves. The frequency, amplitude and duration of the sound waves are dynamically adjusted according to the operation data of the coal-fired boiler, so as to precisely control the coal powder combustion process; the operation data includes boiler load change, furnace temperature, pressure fluctuation and coal powder flow. The device for stabilizing combustion of a coal-fired boiler by using sound waves comprises a sound wave generating device, a control unit and a sound wave transmission structure; the control unit is used for controlling the sound wave generating device to generate sound waves with specific frequency and amplitude; the sound wave transmission structure is used for introducing the sound waves into the furnace and uniformly distributing the sound waves in the furnace; the control unit is also used for receiving the operation data of the coal-fired boiler and dynamically adjusting the frequency, amplitude and duration of the sound waves generated by the sound wave generating device according to the operation data, so as to precisely control the coal powder combustion process; the operation data includes boiler load change, furnace temperature, pressure fluctuation and coal powder flow. The sound wave generating device adopts high-performance piezoelectric ceramic sheets as vibration sources. ； ； wherein is the fluctuation of the furnace pressure at the time instant t, is the fluctuation of the acoustic pressure at the time instant t, is the amplitude of the pressure fluctuation, is the amplitude of the acoustic wave.

2. An apparatus for stabilizing combustion using acoustic waves for implementing the method of stabilizing combustion using acoustic waves as claimed in claim 1, characterized in that, The sound wave transmission structure comprises a sound wave guider, a reflecting plate and a loudspeaker; the sound wave guider adopts a streamline design to reduce energy loss of the sound waves during propagation; the reflecting plate is used for reflecting the sound waves to key areas in the furnace to strengthen the mixing of the coal powder and air; and the loudspeaker is used for enhancing the amplitude and coverage range of the sound waves and improving the optimization effect of the sound waves on the combustion process.

3. The device for maintaining combustion using acoustic waves according to claim 2, wherein Sound wave isolation layers are arranged on key components in the sound wave transmission path; the sound wave isolation layers adopt sound wave attenuation materials.

4. The device for maintaining combustion with sound waves according to claim 2, wherein The sound wave generating device is installed at a primary air nozzle of the coal-fired boiler and does not affect the normal output of the primary air.

5. The apparatus for maintaining combustion with sound waves of claim 4, wherein, The control unit also has monitoring and alarm functions; when it is detected that the operation state of the coal-fired boiler is abnormal or a fault is about to occur, the control unit can timely warn the operator.

6. The device for maintaining combustion with sound waves according to claim 2, wherein The device for stabilizing combustion of a coal-fired boiler by using sound waves comprises the device for stabilizing combustion of a coal-fired boiler by using sound waves according to any one of claims 2 to 7.

7. The device for maintaining combustion with sound waves according to claim 2, wherein ​ 8. A pulverized coal burner characterized by comprising: ​

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