A low-pressure arc ignition and stable combustion device and method for power station boilers

Abstract

The present invention discloses a low-voltage arc ignition and combustion stabilization device and method for a power station boiler. A pair of electrode plates are fixed at intervals on both sides of a heating channel; insulating plates are fixed above and below each electrode plate in the heating channel; a control valve is provided at the bottom of the heating channel, which is fixed to the coal particle inlet of the boiler; a funnel is fixed to the top of the heating channel; an inner tube is provided with an air flow channel, the air outlet of the air flow channel is connected to the air inlet of the boiler; the space between the inner tube and the outer tube is a pulverized coal air flow channel; the pulverized coal outlet of the pulverized coal air flow channel is connected to the pulverized coal inlet of the boiler. The present invention utilizes a low-voltage arc to generate a thermal effect on moving pulverized coal particles, causing them to heat up to the ignition point. The particles then encounter the pulverized coal airflow and air flow, causing combustion, thereby igniting the boiler and achieving higher combustion efficiency. Furthermore, during low-load operation, the pulverized coal airflow concentration is reduced or the air flow rate is increased, ensuring uniform combustion within the boiler and maintaining combustion stability in the power station boiler.

Description

Technical Field

[0001] The invention belongs to the field of ignition and combustion of pulverized coal boilers in power stations, and in particular relates to a low-voltage arc ignition and stabilization combustion device and method for power station boilers. Background Art

[0002] There are two main traditional ignition methods for pulverized coal boilers in power plants. The first involves using a large oil gun or a small oil gun with a belt ignition. Before the power plant pulverized coal boiler is started, the oil gun is then inserted into the combustion zone within the boiler, feeding pulverized coal and heating it until combustion stabilizes. The gun is then removed. The drawbacks of this ignition method are high fuel consumption and pollution caused by incomplete combustion. The second method involves plasma ignition, which uses direct current to ionize compressed air, generating a stable, directional plasma arc. This plasma arc then reacts with the pulverized coal particles within the combustion chamber, causing a chemical reaction that fragments and ignites the particles, ultimately igniting the entire pulverized coal stream. Plasma ignition is particularly effective when igniting lean and anthracite coals, resulting in incomplete combustion within the boiler, unstable ignition, and low combustion stability and burnout rates. Furthermore, the plasma electrode can become contaminated and worn during use, requiring timely replacement.

[0003] In summary, traditional ignition methods require a large amount of fuel oil, resulting in significant coking and wear issues. Plasma ignition technology also suffers from unstable ignition, requiring combustion aid, and electrode susceptibility to coal dust contamination. Furthermore, both ignition methods face challenges with stable combustion, resulting from uneven combustion within power plant boilers at low loads. Summary of the Invention

[0004] The purpose of the present invention is to address the fuel oil waste problems existing in the prior art and the stable combustion problems caused by uneven internal combustion of power station boilers under low load conditions, and to propose a low-pressure arc ignition and stable combustion device and method for power station boilers. A low-pressure arc is used to produce a thermal effect on the moving coal powder particle resistor body, so that it spontaneously heats up through its own resistance heat, so that the coal powder particles reach the ignition point, and then are ignited after meeting the incoming oxygen-rich coal powder airflow. The ignited coal powder particles enter the boiler interior along with the incoming coal powder airflow, thereby realizing boiler ignition.

[0005] The present invention provides a low-pressure arc ignition and stabilization device for a power station boiler, comprising a funnel, a low-pressure arc heating device, an airflow conveying device, and a boiler. The low-pressure arc heating device comprises a heating channel, an insulating plate, an electrode plate, a temperature sensor, and a control valve. A pair of electrode plates are fixed at intervals on both sides of the heating channel; insulating plates are fixed above and below each electrode plate in the heating channel. The detection end of the temperature sensor extends into the heating channel; the control valve is arranged at the bottom end of the heating channel, which is fixed at the coal particle inlet of the boiler; and the funnel is fixed at the top end of the heating channel. The airflow conveying device comprises an inner tube and an outer tube fixed to the side of the boiler. The inner tube is provided with an air flow channel, the air outlet of the air flow channel being connected to the air inlet of the boiler. The space between the inner tube and the outer tube is a coal powder airflow channel; the coal powder outlet of the coal powder airflow channel is connected to the coal powder inlet of the boiler.

[0006] Preferably, the low-voltage arc heating device is provided in plurality, the heating channels of adjacent low-voltage arc heating devices are fixedly connected end to end, the bottom end of the heating channel of the bottommost low-voltage arc heating device is fixed at the coal particle inlet of the boiler; the funnel is fixed at the top end of the heating channel of the topmost low-voltage arc heating device.

[0007] Preferably, the air flow channel is longer than the coal powder air flow channel.

[0008] Preferably, the front half of the pulverized coal airflow channel is cylindrical, and the rear half is a Venturi cylinder with thick sides and a thin middle.

[0009] More preferably, the outer cylinder is fixed to the boiler via a support arm, and reinforcing ribs are provided between the support arm, the boiler and the outer wall of the outer cylinder.

[0010] More preferably, a spoiler assembly is also provided, which includes a bolt, a nut, a spring, a cylindrical drum and a spoiler; the bolt is fixed on the inner side of the support arm, and the nut is connected to the bolt; the spoiler is hinged to the inner wall of the outer cylinder through the cylindrical drum; the spring passes through the through hole opened in the outer cylinder, and the two ends are connected to the spoiler and the nut.

[0011] Preferably, the length of the electrode plate is selected from 60 to 80 cm, the width is selected from 15 to 30 cm, and the thickness is selected from 2 to 5 mm.

[0012] The ignition method of the low-pressure arc ignition and stabilization device of the power station boiler has the following specific steps:

[0013] Step 1: Use a crusher to crush the granular coal, and then screen out the coal particles with a particle size of 0.1 to 2 mm.

[0014] Step 2: Adjust the nut closer to the support arm. The nut exerts tension on the spring, causing the baffle to rotate around the cylindrical roller toward the inner wall of the outer cylinder. Pour the coal particles obtained in Step 1 into the funnel and close the funnel lid. Power is applied to the electrode plates, and the control valve is opened to adjust the flow rate of the coal particles in the heating channel. The low-voltage arc generated between the electrode plates acts on the coal particles moving downward along the heating channel. The coal particles generate heat during movement, increasing their temperature. Once they reach their ignition point, they enter the boiler.

[0015] Step 3: The pulverized coal airflow channel conveys the pulverized coal airflow, while the airflow channel conveys air. When the pulverized coal airflow reaches the second half of the pulverized coal airflow channel, the Venturi effect increases the pulverized coal concentration in the pulverized coal airflow. The pulverized coal airflow then enters the boiler through the pulverized coal inlet and mixes with the coal particles that have reached the ignition point and the air transported into the boiler through the airflow channel, igniting the coal particles. This process continues until the entire boiler is ignited. Because the second half of the pulverized coal airflow channel is a Venturi-cylinder-shaped channel, the pulverized coal airflow diverges in all directions upon entering the boiler, resulting in a uniform pulverized coal concentration within the boiler.

[0016] Preferably, after the boiler is ignited, the adjusting nut moves away from the supporting arm, the spring generates pressure acting on the baffle, and the baffle rotates around the cylindrical roller in a direction away from the inner wall of the outer cylinder.

[0017] Preferably, when the boiler is in a low-load state, the concentration of the pulverized coal airflow is reduced or the air flow rate is increased to ensure uniform combustion inside the boiler.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention addresses the waste of fuel oil during the ignition process of power station boilers and the need for stable combustion under low-load operation. A low-voltage arc ignition and stable combustion device is designed. This device utilizes a low-voltage arc to generate a thermal effect on the moving coal powder particle resistor, causing it to spontaneously heat up through its own resistance heat, bringing the coal powder particles to the ignition point. The coal particles that reach the ignition point then meet the coal powder airflow and air flow, causing them to burn, thereby igniting the boiler and achieving higher combustion efficiency. Furthermore, during low-load operation, the concentration of the coal powder airflow can be reduced or the air flow rate can be increased to ensure uniform combustion within the boiler, thereby maintaining the stability of the power station boiler's combustion. Furthermore, this ignition method utilizes stable and controllable clean electricity energy, avoiding fuel oil waste and air pollution.

[0020] 2. The electrode plates used for heating in the device of the present invention are made of graphite, which is more corrosion-resistant and has a longer service life than the stainless steel electrode plates used for plasma ignition.

[0021] 3. Compared with the traditional oil gun ignition method and plasma ignition method, the ignition method of the present invention has a wider range of applications and can be used for various types of pulverized coal power station boilers such as lean coal and anthracite. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the device of the present invention.

[0023] Figure 2 It is a cross-sectional view of the air flow conveying device of the present invention.

[0024] Figure numerals: 1 is a funnel; 2 is an insulating plate; 3 is an electrode plate; 4 is a power terminal; 5 is a temperature sensor; 6 is a control valve; 7 is an air flow channel; 8 is an inner cylinder; 9 is a coal powder air flow channel; 10 is an outer cylinder; 11 is a support arm; 12 is a bolt; 13 is a nut; 14 is a spring; 15 is a reinforcing rib; 16 is a cylindrical roller; 17 is a spoiler. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] like Figure 1 and Figure 2 As shown, a low-pressure arc ignition and combustion stabilization device for a power station boiler includes a funnel 1, a low-pressure arc heating device, an air flow conveying device and a boiler.

[0027] The low-voltage arc heating device includes a heating channel, an insulating plate 2, an electrode plate 3, a power supply terminal 4, a temperature sensor 5, and a control valve 6. A pair of electrode plates 3 are fixed at intervals on either side of the heating channel and are each connected to the positive and negative terminals of the power supply via a power supply terminal 4. Insulating plates 2 are fixed to the upper and lower sides of each electrode plate 3 within the heating channel. The detection end of the temperature sensor 5 extends into the heating channel to detect the temperature within the channel. The control valve 6 is located at the bottom of the heating channel to control the flow rate of coal particles within the heating channel. There are multiple low-voltage arc heating devices. A funnel 1 is fixed to the top of the heating channel of the topmost low-voltage arc heating device, and a retractable funnel cover is provided at the top of the funnel 1. When there is only one low-voltage arc heating device, the bottom end of the heating channel of each low-voltage arc heating device is fixed to the coal particle inlet of the boiler. When there are more than one low-voltage arc heating device, the heating channels of adjacent low-voltage arc heating devices are fixed end to end, and the bottom end of the heating channel of the bottommost low-voltage arc heating device is fixed to the coal particle inlet of the boiler.

[0028] The air flow conveying device includes an inner cylinder 8 and an outer cylinder 10 fixed to the side of the boiler. The inner cylinder 8 is provided with an air flow channel 7 for conveying air to the boiler. The air inlet of the air flow channel 7 is provided with an openable and closable cylinder cover, and the air outlet of the air flow channel 7 is connected to the air inlet of the boiler. The space between the inner cylinder 8 and the outer cylinder 10 is a pulverized coal air flow channel 9 for conveying pulverized coal airflow to the boiler. The front half of the pulverized coal air flow channel 9 is cylindrical, and the back half is a Venturi cylinder with thick sides and thin middle. The pulverized coal outlet of the pulverized coal air flow channel 9 is connected to the pulverized coal inlet of the boiler. The air flow channel 7 is longer than the pulverized coal air flow channel 9. Preferably, the outer cylinder 10 is fixed to the boiler by a support arm 11, and reinforcing ribs 15 are provided between the support arm 11 and the outer wall of the boiler and the outer cylinder 10. More preferably, a spoiler assembly is provided, comprising a bolt 12, a nut 13, a spring 14, a cylindrical roller 16, and a spoiler 17. Bolt 12 is secured to the inner side of support arm 11, and nut 13 is connected to bolt 12. Spoiler 17 is hingedly connected to the inner wall of outer cylinder 10 via cylindrical roller 16 and can rotate about cylindrical roller 16. Spring 14 passes through a through hole defined in outer cylinder 10, with its ends connecting spoiler 17 and nut 13. Multiple spoiler assemblies are provided, and when the number exceeds one, they are evenly distributed along the circumference of outer cylinder 10.

[0029] The ignition method of the low-pressure arc ignition and stabilization device of the power station boiler has the following specific steps:

[0030] Step 1: Use a crusher to crush the granular coal, and then screen out the coal particles with a particle size of 0.1 to 2 mm.

[0031] Step 2: Adjust the nut 13 close to the support arm 11. The nut 13 generates a pulling force on the spring 14, causing the baffle 17 to rotate around the cylindrical roller 16 toward the inner wall of the outer cylinder 10. Pour the coal particles obtained in step 1 into the funnel and close the funnel cover to prevent dust. Power on the electrode plates, open the control valve 6 and adjust the flow rate of the coal particles in the heating channel. The low-voltage arc (voltage of 0 to 380V) generated between the electrode plates acts on the coal particles moving downward along the heating channel. The coal particles will generate heat and heat up during the movement. The coal particles pass through multiple low-voltage arc heating devices and eventually reach their own ignition point before entering the boiler.

[0032] Step 3: The pulverized coal airflow channel conveys the pulverized coal airflow, and the airflow channel conveys air (or oxygen-enriched air), wherein both the air and the pulverized coal airflow are conveyed by a speed-controlled fan. When the pulverized coal airflow reaches the second half of the pulverized coal airflow channel 9, the pulverized coal concentration in the pulverized coal airflow increases due to the Venturi effect. The pulverized coal is mixed with the coal particles that have entered the boiler and reached the ignition point, as well as the air conveyed by the airflow channel, causing the coal particles to ignite. This process continues until the entire boiler is ignited. Since the second half of the pulverized coal airflow channel is a Venturi-cylinder-shaped channel, the pulverized coal airflow diverges in all directions when entering the boiler. The pulverized coal concentration of the pulverized coal airflow within the boiler is balanced, resulting in relatively stable combustion conditions within the boiler.

[0033] Preferably, after the boiler is ignited, the adjusting nut 13 is moved away from the support arm 11, and the spring generates pressure acting on the baffle 17, and the baffle 17 rotates around the cylindrical roller 16 in a direction away from the inner wall of the outer cylinder 10. The limit state is close to perpendicular to the coal powder airflow channel to prevent the boiler from backfire.

[0034] Preferably, when the boiler is in a low-load state, the speed of the speed-regulating fan can be adjusted to reduce the concentration of the pulverized coal airflow or increase the air flow rate to ensure uniform combustion inside the boiler, thereby solving the problem of stable combustion under low-load conditions.

Claims

1. A low-pressure arc ignition and combustion stabilization device for a power station boiler, comprising a funnel and a boiler, characterized in that: It also includes a low-voltage arc heating device and an air flow conveying device; the low-voltage arc heating device includes a heating channel, an insulating plate, an electrode plate, a temperature sensor and a control valve; a pair of electrode plates are fixed at a distance on both sides of the heating channel; insulating plates are fixed above and below each electrode plate in the heating channel; the detection end of the temperature sensor extends into the heating channel; the control valve is arranged at the bottom end of the heating channel, and the bottom end of the heating channel is fixed at the coal particle inlet of the boiler; the funnel is fixed at the top end of the heating channel; the air flow conveying device includes an inner cylinder and an outer cylinder fixed on the side of the boiler; the inner cylinder is provided with an air flow channel, and the air outlet of the air flow channel is connected to the air inlet of the boiler; the space between the inner cylinder and the outer cylinder is a coal powder air flow channel; the front half of the coal powder air flow channel is cylindrical, and the rear half is a Venturi cylinder with thick sides and thin middle; the coal powder outlet of the coal powder air flow channel is connected to the coal powder inlet of the boiler.

2. A low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 1, characterized in that: There are multiple low-voltage arc heating devices, and the heating channels of adjacent low-voltage arc heating devices are fixedly connected end to end. The bottom end of the heating channel of the bottommost low-voltage arc heating device is fixed at the coal particle inlet of the boiler; the funnel is fixed at the top end of the heating channel of the topmost low-voltage arc heating device.

3. The low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 1, characterized in that: The air flow channel is longer than the coal powder air flow channel.

4. The low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 1, characterized in that: The outer cylinder is fixed to the boiler via a support arm, and reinforcing ribs are provided between the support arm, the boiler and the outer wall of the outer cylinder.

5. The low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 4, characterized in that: A spoiler assembly is also provided, which includes a bolt, a nut, a spring, a cylindrical roller and a spoiler; the bolt is fixed on the inner side of the support arm, and a nut is connected to the bolt; the spoiler is hinged to the inner wall of the outer cylinder through the cylindrical roller; the spring passes through a through hole opened in the outer cylinder, and the two ends are connected to the spoiler and the nut.

6. The low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 1, characterized in that: The length of the electrode plate is selected from 60 to 80 cm, the width is selected from 15 to 30 cm, and the thickness is selected from 2 to 5 mm.

7. The ignition method of a low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 5, characterized in that: The specific steps of this method are as follows: Step 1: Use a crusher to crush the granular coal, and then screen out the coal particles with a particle size of 0.1 to 2 mm; Step 2: Adjust the nut close to the support arm. The nut generates tension on the spring, causing the baffle to rotate around the cylindrical roller toward the inner wall of the outer cylinder. Pour the coal particles obtained in step 1 into the funnel and close the funnel cover. Power the electrode plates, open the control valve, and adjust the flow rate of the coal particles in the heating channel. The low-voltage arc generated between the electrode plates acts on the coal particles moving downward along the heating channel. The coal particles generate heat during movement and heat up. After reaching their own ignition point, they enter the boiler. Step three, the pulverized coal airflow channel conveys the pulverized coal airflow, and the air flow channel conveys air; when the pulverized coal airflow reaches the second half of the pulverized coal airflow channel, the pulverized coal concentration in the pulverized coal airflow increases due to the Venturi effect, and then the pulverized coal airflow enters the boiler from the pulverized coal inlet of the boiler, and is mixed with the coal particles that have entered the boiler and reached the ignition point, as well as the air conveyed into the boiler through the air flow channel, so that the coal particles are ignited, and this process is continued to ignite the entire boiler; wherein, since the second half of the pulverized coal airflow channel is a Venturi cylindrical type, the pulverized coal airflow is in a divergent state when entering the boiler, and the pulverized coal concentration of the pulverized coal airflow in the boiler is balanced.

8. The ignition method of a low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 7, characterized in that: After the boiler is ignited, the adjusting nut moves away from the supporting arm, the spring generates pressure acting on the spoiler, and the spoiler rotates around the cylindrical roller in a direction away from the inner wall of the outer cylinder.

9. The ignition method of a low-pressure arc ignition and combustion stabilization device for a power station boiler according to claim 7, characterized in that: When the boiler is in a low-load state, reduce the concentration of the pulverized coal airflow or increase the air flow rate to ensure uniform combustion inside the boiler.

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