Device and method for reducing abrasion of heating surface of boiler

Abstract

The invention discloses a device and method for reducing abrasion of a heating surface of a boiler, and the device is characterized in that a high-strength sound source is arranged on the side surface of an upstream flue of the heating surface, and a standing wave sound field is formed in the flue in the working process of the sound source; the heating surface pipes are arranged in sequence, are distributed along the width direction of the flue, are matched with the standing wave sound field, and are arranged at wave nodes of the standing wave sound field; the high-strength standing wave sound field forms obvious antinode and node, the antinode is high in vibration velocity and low in sound pressure, and the node is low in vibration velocity and high in sound pressure; dust particles in the flue tend to gather at an antinode under the driving of acoustic radiation force; due to the fact that the heating surface pipes are arranged at the wave nodes of the standing wave sound field, dust mainly penetrates through the gaps between the pipes, the pipes are prevented from being directly scoured, and abrasion is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of boilers, and in particular to a device and method for reducing the wear of a boiler heating surface. Background Art

[0002] In my country, low-quality coal is widely distributed and has huge reserves. Low-quality coal usually refers to coal with low calorific value, high sulfur content and high ash content. These coals will produce more pollutants when burned, causing greater pressure on the environment.

[0003] Clean and efficient utilization of low-quality coal is an important research direction in my country's current energy field. With the continuous growth of my country's economy, the demand for energy continues to increase, and as one of my country's main energy sources, the efficient and clean utilization of coal is particularly important.

[0004] Due to its high ash content, low-quality coal will cause serious wear problems on the heating surface of the boiler during the combustion process. High ash content means that more dust will be produced when the coal is burned. As the flue gas flows, it will wash the heating surface and cause wear. In addition, when low-quality coal is burned, slag may form on the heating surface of the boiler. The accumulation of slag not only affects the heat transfer efficiency, but also may cause mechanical damage to the heating surface due to the shedding of slag blocks.

[0005] In order to deal with this problem, some technical measures have been proposed to reduce or prevent the wear of the heating surface. For example, by adjusting the combustion method, such as centralized combustion and improving the configuration of the first, second and third air, the furnace temperature can be increased, which is conducive to the stable ignition and combustion of coal powder and reduces the dust content, but the effect is usually ineffective. The wear resistance of the heating surface can be improved through material selection, surface treatment and other methods, but the cost is relatively high and the economy is poor. In addition, the wear of the heating surface can be reduced by arranging anti-wear tiles at the entrance of the heating surface, but the anti-wear tiles will reduce the heat transfer coefficient of the heating surface. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, the present invention provides a device and method for reducing the wear of the heating surface of a boiler.

[0007] The technical solution of the present invention is as follows:

[0008] A device for reducing the wear of the boiler heating surface is to arrange a high-intensity sound source on the side of the flue upstream of the heating surface, and the direction of the sound wave radiated by the sound source is perpendicular to the direction of the flue gas flow;

[0009] Furthermore, the heating surface tubes are arranged in series, and the distribution along the flue width W direction is consistent with the standing wave sound field. They are arranged at the wave nodes of the standing wave sound field, and the tube spacing L=λ.

[0010] Furthermore, when the high-intensity sound source is working, the relationship between the sound wave wavelength λ and the flue width W is: W = (N+0.5)λ, where N is the number of rows of the heating surface tubes along the flue width W.

[0011] Furthermore, the inner wall of the flue opposite to the sound source is flat and perpendicular to the radiation direction of the sound wave, so as to allow the sound wave to be reflected in the opposite flue to form a standing wave.

[0012] Furthermore, the high-intensity sound source is made of heat-resistant materials such as stainless steel and can work in a high-dust environment, such as a pneumatic sound source driven by compressed air; the sound pressure level generated by the sound source is not less than 120dB.

[0013] Furthermore, when the flue gas temperature and composition change, the wavelength of the sound wave also changes, so the frequency of the high-intensity sound source should be adjustable.

[0014] One method to reduce boiler heating surface wear is as follows:

[0015] 1) According to the flue gas temperature and components where the heating surface is located, the sound velocity C in the flue gas is calculated;

[0016] 2) According to the relationship between the sound wave wavelength λ and the flue width W, W = (N + 0.5)λ, the sound wave wavelength is obtained to be λ, and the sound source operating frequency f = C / λ is further obtained. The sound source parameters are adjusted to make it work at the frequency f, and the sound intensity is adjusted to make the sound pressure level higher than 120dB.

[0017] 3) When the above conditions are met, a high-intensity standing wave sound field is generated in the flue, forming obvious antinodes and nodes. The antinodes have high vibration velocity and low sound pressure, while the nodes have low vibration velocity and high sound pressure. Driven by the acoustic radiation force, the dust particles in the flue tend to gather at the antinodes.

[0018] 4) Since the heating surface tubes are arranged at the nodes of the standing wave acoustic field, the dust mainly passes through the gaps between the tubes, avoiding direct erosion of the tubes, thereby greatly reducing wear.

[0019] The beneficial effects of the present invention are:

[0020] 1) The present invention uses the radiation force of a high-intensity sound field on dust particles to gather the dust and make it pass through the gaps in the heat exchange tube bundle, thereby preventing the dust from directly scouring the heat exchange tubes. The method is unique and the effect is remarkable.

[0021] 2) The present invention reduces the wear of the boiler heating surface by setting a sound source without increasing the system resistance.

[0022] 3) The technical solution of the present invention is easy to implement and is particularly suitable for the transformation of existing boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of the structure of the device of the present invention;

[0024] Figure 2 The velocity distribution of the sound field generated by the sound source when the present invention is working;

[0025] Figure 3 The pressure distribution of the sound field generated by the sound source when the present invention is working;

[0026] Figure 4 The movement of dust particles in the flue and the heating surface when the present invention is working;

[0027] Figure 5 The experimental results of high-intensity sound source on the distribution of dust particles;

[0028] In the figure, 1-flue; 2-sound source; 3-heating surface; 4-sound wave vibration velocity distribution; 5-sound pressure distribution, black represents higher sound pressure, white represents lower sound pressure; 6-dust distribution upstream of the sound source; 7-dust distribution downstream of the sound source. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0030] like Figure 1 As shown, a device for reducing the wear of the boiler heating surface is to arrange a sound source 2 on the side of the flue 1 upstream of the heating surface, and the direction of the sound wave radiated by the sound source is perpendicular to the direction of the flue gas flow in the flue 2; the inner wall of the flue opposite to the sound source is a plane and perpendicular to the sound wave radiation direction.

[0031] When the sound source 2 is working, the relationship between the sound wave wavelength λ and the width W of the flue 2 is: W=(N+0.5)λ, where N is the number of rows of the heating surface 3 along the width W of the flue 2.

[0032] The sound pressure level generated by sound source 2 is not less than 120dB, forming a high-intensity sound source.

[0033] like Figure 2 As shown, the high-intensity sound source forms a standing wave during operation, and the distribution of the sound wave vibration velocity is shown in Figure 4. The pipes of the heating surface 3 are arranged in series, and the distribution along the width W of the flue 2 is consistent with the standing wave sound field, and are arranged at the wave nodes of the standing wave sound field, and the pipe spacing L = λ.

[0034] like Figure 3 As shown, a high-intensity sound source forms a standing wave during operation, and the sound pressure distribution is shown in Figure 5. Black represents a higher sound pressure, and white represents a lower sound pressure.

[0035] The sound source 2 is made of heat-resistant materials such as stainless steel, and can work in a high-dust environment, such as a pneumatic sound source driven by compressed air.

[0036] It is required that when the flue gas temperature and composition change, the wavelength of the sound wave also changes accordingly, so the frequency of the sound source 2 should be adjustable.

[0037] Specifically, Figure 4 The device for reducing the wear of the boiler heating surface is shown, and its principle and working method are as follows:

[0038] 1) According to the flue gas temperature and components where the heating surface is located, the sound velocity C in the flue gas is calculated. Taking conventional coal-fired flue gas with a temperature of 600°C as an example, the sound velocity can be calculated to be 592m / s.

[0039] 2) According to the relationship between the sound wave wavelength λ and the flue width W, W = (N + 0.5)λ, the sound wave wavelength is obtained to be λ, and the sound source working frequency f = C / λ is further obtained. Taking the flue width W as 2990mm and the number of tube rows N = 50 as an example, it can be calculated that the required sound wave wavelength is 59.2mm, and the working frequency f = 10kHz is obtained. By adjusting the sound source parameters, it works at 10kHz, and at the same time adjusts the sound intensity to make the sound pressure level higher than 120dB.

[0040] 3) When the above conditions are met, a high-intensity standing wave sound field is generated in the flue, forming obvious antinodes and nodes. The antinodes have high vibration velocity and low sound pressure, while the nodes have low vibration velocity and high sound pressure. The dust particles in the flue are driven by the acoustic radiation force and tend to gather at the antinodes. Figure 4 As shown in Figure 7.

[0041] 4) Since the heating surface tubes are arranged at the nodes of the standing wave acoustic field, the dust particles mainly pass through the gaps between the tubes. Figure 4 As shown in Figure 7, direct flushing of the pipe is avoided, thereby greatly reducing wear.

[0042] Figure 5 The experimental results are shown in Figure 2. The experimental object is coal dust particles dispersed in the pipeline. The experiment was conducted at room temperature, using an adjustable compression driver as the sound source, with an adjustable frequency, a sound wave frequency of 1500Hz, and a sound intensity of 131dB. Figure 5 (a) shows the dust in the pipe without ultrasonic treatment, and it can be found that the dust particles are evenly distributed; Figure 5 In (b), after being treated by the standing wave sound field, the dust particles gather at the antinode of the sound field, which is very obvious and the experimental effect is significant.

[0043] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A device for reducing the wear of a boiler heating surface, comprising a flue (1) and a heating surface (3) arranged on the flue (1), characterized in that: A sound source (2) is arranged on the side of the flue upstream of the heating surface (3); the direction of the sound wave radiated by the sound source (2) is perpendicular to the direction of flue gas flow in the flue; when the sound source (2) is in operation, a standing wave sound field is generated in the flue (1), and dust particles in the flue are driven by the radiation force of the sound source (2) and tend to gather at the antinode; the pipes on the heating surface (3) are arranged at the nodes of the standing wave sound field along the flue width W.

2. The device for reducing wear of boiler heating surface according to claim 1, characterized in that: The tubes on the heating surface (3) are arranged in series and distributed along the flue width W. The spacing between the tubes along the flue width W is L=λ, and the wavelength of the sound wave is λ.

3. The device for reducing wear of boiler heating surface according to claim 1, characterized in that: The inner wall of the flue opposite to the sound source (2) is a plane and is perpendicular to the radiation direction of the sound waves.

4. The device for reducing wear of boiler heating surface according to claim 1, characterized in that: The relationship between the sound wave wavelength λ of the sound source (2) and the flue width W of the flue (1) is: W=(N+0.5)λ, wherein N is the number of rows of the heating surface pipes along the flue width W.

5. The device for reducing wear of boiler heating surface according to claim 1, characterized in that: The sound source (2) is made of heat-resistant material, and the sound pressure level generated by the sound source is not less than 120 dB.

6. The device for reducing wear of boiler heating surface according to claim 1, characterized in that: The frequency of the sound source (2) is adjustable, so that the sound wave wavelength λ of the sound source changes with the temperature and composition of the flue gas.

7. A method for reducing wear of a boiler heating surface, comprising the following steps: 1) According to the flue gas temperature and components where the heating surface is located, the sound velocity C in the flue gas is calculated; 2) According to the relationship between the sound wave wavelength λ and the flue width W W = (N + 0.5)λ, the sound wave wavelength is λ and the sound source working frequency f = C / λ; the sound source parameters are adjusted so that the sound source works at the frequency f, and the sound intensity is adjusted so that the sound pressure level is higher than 120dB; 3) When a high-intensity sound source that meets the above conditions is working, a standing wave sound field is generated in the flue, forming antinodes and nodes. The antinodes have high vibration velocity and low sound pressure, while the nodes have low vibration velocity and high sound pressure. The dust particles in the flue are driven by the sound radiation force and tend to gather at the antinodes. 4) Since the heating surface tubes are arranged at the nodes of the standing wave acoustic field, the dust passes through the gaps between the tubes, avoiding direct scouring of the tubes, thereby greatly reducing wear.

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