Plasma ignition system for coal-fired boiler

Abstract

The utility model provides a plasma ignition system for a coal-fired boiler. The plasma ignition system for the coal-fired boiler comprises a coal-fired boiler body, and a plasma burner communicated with a hearth of the coal-fired boiler body is arranged in the coal-fired boiler body; the plasma generator penetrates through the coal-fired boiler body, communicates with the plasma combustor and is used for generating high-temperature plasma jet flow and introducing the high-temperature plasma jet flow into the plasma combustor; a coal outlet of the coal mill communicates with the plasma combustor through a pulverized coal conveying pipeline, and the end, close to the coal outlet of the coal mill, of the pulverized coal conveying pipeline communicates with an air supply pipe; and the combustion-supporting pipeline penetrates through the coal-fired boiler body, communicates with a hearth of the coal-fired boiler body and is used for introducing combustion-supporting gas into the hearth of the coal-fired boiler body. Compared with the mode that a coal-fired boiler is ignited through an oil gun in the prior art, the high-temperature plasma jet flow generated by the plasma generator is used for igniting the pulverized coal, the fuel oil consumption is reduced, and the ignition efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of coal-fired boiler technology, and in particular to a plasma ignition system for coal-fired boilers. Background Technology

[0002] With economic development, my country has become the world's second-largest oil consumer and importer, after the United States. my country has relatively abundant coal resources but relatively scarce oil resources; its recoverable coal reserves account for 11.63% of the world's total, while its oil reserves account for only 2.67%. Therefore, conserving and substituting fuel oil is of great strategic significance for alleviating the contradiction between oil supply and demand, conserving energy, and achieving energy conservation and emission reduction.

[0003] Currently, coal-fired boilers in domestic power plants are typically equipped with bowl-type medium-speed mill direct-fired pulverizing systems. The ignition device uses a direct-flow, four-corner tangential combustion system, meaning the boiler has approximately 12 oil guns with a capacity of 1–1.25 t / h. The oil guns are designed for stable combustion with a BMCR below 40%. Under normal circumstances, to prevent low-load flameout, stable combustion is required for boilers with a capacity of less than 150 MW, with a fuel consumption of 2–6 t / h. However, the above-mentioned ignition system consumes excessively high fuel oil during cold starts. Normal cold start fuel consumption is 85 tons per unit, and normal shutdown fuel consumption is 8 tons per unit. This means that the commissioning, start-up, shutdown, and low-load stable combustion of coal-fired boilers in thermal power generating units consume a large amount of fuel oil. Furthermore, with the increasing frequency and depth of grid peak shaving, fuel oil consumption and the number of unit start-ups and shutdowns will inevitably increase, significantly increasing power generation costs and hindering energy conservation, emission reduction, and environmentally friendly production. Based on this, this application provides a plasma ignition system for coal-fired boilers. Utility Model Content

[0004] This application provides a plasma ignition system for a coal-fired boiler to solve the technical problems described in the background section.

[0005] To solve the above-mentioned technical problems, this application adopts the following technical solution:

[0006] This application provides a plasma ignition system for a coal-fired boiler, comprising:

[0007] The coal-fired boiler body is equipped with a plasma burner that communicates with its furnace.

[0008] A plasma generator, which penetrates the coal-fired boiler body and is connected to the plasma burner, is used to generate a high-temperature plasma jet and inject the high-temperature plasma jet into the plasma burner;

[0009] A coal mill, wherein the coal outlet of the coal mill is connected to the plasma burner through a pulverized coal conveying pipe, and an air supply pipe is connected to one end of the pulverized coal conveying pipe near the coal outlet of the coal mill.

[0010] A combustion-supporting pipe, which penetrates the coal-fired boiler body and communicates with the furnace of the coal-fired boiler body, is used to introduce combustion-supporting gas into the furnace of the coal-fired boiler body.

[0011] Optionally, a first air volume regulating valve is provided on the air supply duct;

[0012] A pulverized coal flow meter is installed on the pipe between the coal mill and the air supply pipe.

[0013] Optionally, the end of the air supply pipe away from the pulverized coal conveying pipe is used to connect to a hot air source, and a cold air pipe is connected thereto, the end of the cold air pipe away from the air supply pipe being used to connect to a cold air source.

[0014] The air supply duct is equipped with a second air volume regulating valve on the duct body between the hot air source and the cold air duct, and a third air volume regulating valve is equipped on the cold air duct.

[0015] Optionally, the end of the combustion-supporting pipe away from the coal-fired boiler body is connected to the hot air outlet of the air preheater, the heat exchange medium inlet of the air preheater is connected to the steam outlet of the coal-fired boiler body through a steam pipe, and the heat exchange medium outlet of the air preheater is connected to the water inlet of the economizer through a condensate pipe.

[0016] Optionally, a circulating water pump is installed on the condensate pipe.

[0017] Optionally, there are multiple combustion-supporting pipes, which are connected to the furnace of the coal-fired boiler body around the plasma generator, and each combustion-supporting pipe forms a preset angle with the plasma burner.

[0018] The preset included angle is an acute angle.

[0019] Optionally, each of the combustion-supporting pipes is equipped with a fourth air volume regulating valve.

[0020] Optionally, an induced draft fan is installed on both the air supply pipe near the pulverized coal conveying pipe and the combustion-supporting pipe.

[0021] Optionally, the plasma generator is a DLZ-200 or THPI-300 / 600 model.

[0022] The plasma ignition system for coal-fired boilers provided in this application uses an air supply pipe to drive pulverized coal generated by the coal mill into the plasma burner, increasing the rate at which pulverized coal enters the plasma burner and improving its dispersion. A high-temperature plasma jet is generated by the plasma generator, and this jet enters the plasma burner, causing the pulverized coal to rapidly break up and burn, thus improving the combustion efficiency. The flame from the burning pulverized coal quickly enters the furnace of the coal-fired boiler, rapidly heating the furnace. Simultaneously, combustion air is introduced into the furnace through a combustion-supporting pipe, accelerating the combustion rate of the pulverized coal and further improving the heating efficiency of the furnace. Compared to existing technologies that ignite coal-fired boilers using oil guns, this application uses a high-temperature plasma jet generated by a plasma generator to ignite pulverized coal, which saves fuel consumption and improves ignition efficiency. In addition, the installation of the plasma burner, air supply pipe, and combustion-supporting pipe improves the combustion efficiency of pulverized coal and the stability of the combustion process. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a plasma ignition system for a coal-fired boiler provided in one embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of a plasma ignition system for a coal-fired boiler provided in another embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the structure of a plasma ignition system for a coal-fired boiler provided in another embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of a plasma ignition system for a coal-fired boiler provided in another embodiment of this application.

[0028] In the diagram: 100, Coal-fired boiler body; 101, Plasma burner; 200, Plasma generator; 300, Coal mill; 301, Pulverized coal conveying pipeline; 3011, Pulverized coal flow meter; 400, Air supply duct; 401, First air volume regulating valve; 4011, Hot air source; 402, Cold air duct; 4021, Cold air source; 4022, Third air volume regulating valve; 403, Second air volume regulating valve; 500, Combustion aid pipeline; 501, Fourth air volume regulating valve; 600, Air preheater; 601, Steam pipeline; 602, Condensate pipeline; 6021, Circulating water pump; 700, Economizer; 800, Exhaust fan. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0030] refer to Figures 1 to 4 This application provides a plasma ignition system for a coal-fired boiler, comprising:

[0031] The coal-fired boiler body 100 includes a plasma burner 101 connected to its furnace. The plasma burner 101 is a device that utilizes plasma for combustion; its core function is to ignite fuel through the high-temperature characteristics of plasma, achieving efficient combustion. Furthermore, the coal-fired boiler body 100 can be referenced from the specific structure of coal-fired boilers used in thermal power plants, and this application does not specifically limit its designation.

[0032] A plasma generator 200 penetrates the coal-fired boiler body 100 and is connected to the plasma burner 101. It is used to generate a high-temperature plasma jet and direct the high-temperature plasma jet into the plasma burner 101. The plasma generator 200 is a device for generating plasma. Its core function is to ionize gas molecules through an electric field to form high-temperature plasma. This plasma contains a large number of chemically active particles, such as atoms (C, H, O), atomic groups (OH, H2, O2), and ions (O2). - H2 － OH － O － H ＋ (and electrons, etc., can accelerate thermochemical conversion and improve fuel burnout rate.)

[0033] The coal mill 300 has its coal outlet connected to the plasma burner 101 via a pulverized coal conveying pipe 301. The end of the pulverized coal conveying pipe 301 near the coal outlet of the coal mill 300 is connected to an air supply pipe 400. The air supply pipe 400 enables the pulverized coal to be driven into the plasma burner 101 by the air velocity, thereby improving the pulverized coal conveying efficiency.

[0034] A combustion-supporting pipe 500 penetrates the coal-fired boiler body 100 and connects to the furnace of the coal-fired boiler body 100, for introducing combustion-supporting gas into the furnace of the coal-fired boiler body 100. The combustion-supporting gas is air at a certain temperature. By introducing the combustion-supporting gas into the furnace of the coal-fired boiler body 100, the combustion of pulverized coal is accelerated, thereby causing the furnace of the coal-fired boiler body 100 to heat up rapidly.

[0035] The plasma ignition system for coal-fired boilers provided in this application uses an air supply pipe 400 to drive pulverized coal generated by the coal mill 300 into the plasma burner 101, increasing the rate at which pulverized coal enters the plasma burner 101 and improving the dispersion of pulverized coal in the plasma burner 101. A high-temperature plasma jet is generated by the plasma generator 101, and this jet enters the plasma burner 101, causing the pulverized coal to rapidly break up and burn, thus improving the combustion efficiency of the pulverized coal. Furthermore, the flame from the burning pulverized coal rapidly enters the furnace of the coal-fired boiler body 100, causing the furnace of the coal-fired boiler body 100 to heat up rapidly. Simultaneously, combustion air is introduced into the furnace of the coal-fired boiler body 100 through the combustion-supporting pipe 500, accelerating the combustion rate of the pulverized coal and further improving the heating efficiency of the furnace of the coal-fired boiler body 100. Compared to existing technologies that ignite coal-fired boilers using oil guns, this application uses a high-temperature plasma jet generated by a plasma generator 200 to ignite pulverized coal, which saves fuel consumption and improves ignition efficiency. In addition, the installation of the plasma burner 101, the air supply pipe 400, and the combustion-supporting pipe 500 improves the combustion efficiency of pulverized coal and the stability of the combustion process.

[0036] In some embodiments, reference Figure 2 , Figure 3 and Figure 4 In this application, the air supply duct 400 is provided with a first air volume regulating valve 401; wherein, the air volume entering from the air supply duct 400 is regulated by the first air volume regulating valve 401, and the first air volume regulating valve 401 can be set according to actual needs, but this application does not specifically limit it.

[0037] In addition, a pulverized coal flow meter 3011 is installed on the pulverized coal conveying pipeline 301 between the coal mill 300 and the air supply pipe 400. The pulverized coal flow meter 3011 calculates the flow rate of pulverized coal entering the pulverized coal conveying pipeline 301. The specific setting of the pulverized coal flow meter 3011 can be determined according to actual needs, and this application does not impose any specific limitations on it.

[0038] In the above embodiments, the first air volume regulating valve 401 and the pulverized coal flow meter 3011 enable the air volume and pulverized coal to mix in a certain proportion and enter the plasma burner 101 together under the action of the air velocity. This not only accelerates the rate at which pulverized coal enters the plasma burner 101, but also improves the dispersion of pulverized coal by mixing the two in a certain proportion. As a result, the pulverized coal can fully contact the high-temperature plasma jet and burn when it enters the plasma burner 101, thereby improving the combustion efficiency and combustion stability of the pulverized coal.

[0039] In some embodiments, reference Figure 2 and Figure 4 In this application, the end of the air supply duct 400 furthest from the pulverized coal conveying pipe 3011 is connected to the hot air source 4011, and a cold air duct 402 is connected to it. The end of the cold air duct 402 furthest from the air supply duct 400 is connected to the cold air source 4021. The air in the air supply duct 400 not only transports pulverized coal to the plasma burner 101, but also dries the pulverized coal exiting the coal mill 300. If the temperature of the air entering the air supply duct 400 is too high, it may waste the heat source used for heating the air; if the air temperature is too low, it may result in insufficient drying of the pulverized coal. Therefore, air at a suitable temperature is obtained by mixing cold and hot air and then enters the air supply duct 400 and the pulverized coal conveying pipe 301 for drying. Furthermore, to accurately control the temperature of the air in the air supply duct 400, a temperature sensor can be installed inside the air supply duct 400 to detect the temperature of the air in the air supply duct 400 in real time.

[0040] In addition, a second air volume regulating valve 403 is installed on the air supply duct 400 between the hot air source 4011 and the cold air duct 402, and a third air volume regulating valve 4022 is installed on the cold air duct 402. The second and third air volume regulating valves 403 and 4022 respectively regulate the amount of hot and cold air entering the air supply duct 400, ensuring that the temperature of the mixed hot and cold air is sufficient to dry the coal powder exiting the coal mill 300 without wasting heat.

[0041] In the above embodiment, after the hot air from the hot air source 4011 enters the air supply pipe 400, the amount of hot air entering it is adjusted by the second air volume regulating valve 403. After the cold air from the cold air source 4021 enters the cold air pipe 402, the amount of cold air entering it is adjusted by the third air volume regulating valve 4022. This achieves the goal of drying the coal powder exiting the coal powder outlet of the coal mill 300 by mixing the hot and cold air in a way that avoids wasting heat. The air mixed with the hot and cold air enters the coal powder conveying pipe 301 through the air supply pipe 400 and dries the coal powder in the coal powder conveying pipe 301. This ensures that the coal powder enters the plasma burner 101, contacts the high-temperature plasma inside the plasma burner 101, and burns rapidly.

[0042] In some embodiments, reference Figure 3 and Figure 4 In this application, the end of the combustion-supporting pipe 500 furthest from the coal-fired boiler body 100 is connected to the hot air outlet of the air preheater 600. The heat exchange medium inlet of the air preheater 600 is connected to the steam outlet of the coal-fired boiler body 100 via a steam pipe 601, and the heat exchange medium outlet of the air preheater 600 is connected to the water inlet of the economizer 700 via a condensate pipe 602. The air inlet of the air preheater 600 is used to introduce combustion-supporting gas, which can be air. This air is unheated, and its specific temperature depends on the ambient temperature of the coal-fired boiler body 100.

[0043] In the above embodiments, air is introduced into the air preheater 600 through the air inlet, and high-temperature steam generated by the coal-fired boiler body 100 is introduced into the air preheater 600 through its steam outlet and steam pipe. This allows the high-temperature steam to exchange heat with the air, causing the high-temperature steam temperature to decrease and condense. The condensate then enters the economizer 700 through the condensate pipe 602 and the inlet of the economizer 700, thus achieving the recycling of the condensate after steam condensation. Meanwhile, the air temperature increases and enters the furnace of the coal-fired boiler body 100 through the hot air outlet of the air preheater 600 and the combustion aid pipe 500. The heated air provides the oxygen required for pulverized coal combustion. Compared to unheated air, the heated air in this application enables the pulverized coal to burn quickly, thereby improving the combustion efficiency of the pulverized coal.

[0044] In some embodiments, reference Figure 3 and Figure 4 In this application, a circulating water pump 6021 is installed on the condensate pipe 602.

[0045] In the above embodiments, the condensate after heat exchange with high-temperature steam is transported to the economizer 700 by the circulating water pump 6021. That is, the circulating water pump 6021 provides the power for the condensate to enter the economizer 700. The specifications and model of the circulating water pump 6021 can be set according to actual needs, and this application does not specifically limit it.

[0046] In some embodiments, reference Figure 1 , Figure 3 and Figure 4 This application includes multiple combustion-supporting pipes 500, which surround the plasma generator 200 and connect to the furnace of the coal-fired boiler body 100. Each combustion-supporting pipe 500 forms a predetermined angle with the plasma burner 101. The arrangement of multiple combustion-supporting pipes 500 improves the efficiency of introducing combustion-supporting gas into the coal-fired boiler body 100, thereby improving the combustion efficiency of pulverized coal. Furthermore, the specific number of combustion-supporting pipes 500 can be set according to actual needs, and this application does not impose a specific limitation on it.

[0047] Furthermore, the preset included angle is an acute angle, which allows the combustion-supporting gas ejected from the multiple combustion-supporting pipes 500 into the furnace of the coal-fired boiler body 100 to be quickly dispersed from the flame carrying pulverized coal exiting the plasma burner 101, and to fully contact the combustion-supporting gas with the flame carrying pulverized coal, thereby accelerating the combustion of pulverized coal and increasing the heating efficiency of the furnace of the coal-fired boiler body 100. The preset included angle is 30° or 45°, which can be set according to the actual situation, and this application does not impose a specific limitation on it.

[0048] In some embodiments, reference Figure 3 and Figure 4 Each combustion-supporting pipe 500 in this application is provided with a fourth air volume regulating valve 501.

[0049] In the above embodiments, the amount of combustion-supporting gas entering the furnace of the coal-fired boiler body 100 through each combustion-supporting pipe 500 is adjusted by the fourth air volume regulating valve 501, so that the delivery process of the combustion-supporting gas is precise and controllable, thereby ensuring the stability of the pulverized coal combustion process.

[0050] In some embodiments, reference Figure 2 , Figure 3 and Figure 4 In this application, induced draft fans 800 are installed on both the air supply duct 400 near the pulverized coal conveying pipe 301 and the combustion-supporting pipe 500. The specifications and models of the induced draft fans 800 can be set according to actual needs, and this application does not impose specific limitations on them.

[0051] In the above embodiments, the induced draft fan 800 on the air supply duct 400 draws air into the air supply duct 400, providing the power for transporting air within the air supply duct 400. Additionally, the induced draft fan 800 on the combustion-supporting duct 500 draws combustion-supporting air into the combustion-supporting duct 500, providing the power for transporting combustion-supporting air within the combustion-supporting duct 500.

[0052] In some embodiments, the plasma generator 200 in this application is a DLZ-200 type or a THPI-300 / 600 type.

[0053] In the above embodiments, the DLZ-200 plasma generator 500 uses direct current air plasma as an ignition source, which can directly ignite lean coal with low volatile matter content, enabling cold start-up of the boiler without the need for fuel oil, thereby saving a significant amount of fuel costs and improving ignition safety. The THPI-300 / 600 plasma generator 500 features high power (maximum power exceeding 250kW, effectively igniting lean coal with low volatile matter content), long-life electrodes (cathode life exceeding 200 hours, anode life exceeding 1000 hours, significantly improving equipment lifespan), high electrothermal conversion efficiency (this model boasts an electrothermal conversion efficiency of up to 93%, further enhancing energy utilization efficiency), and flexible adaptability (suitable for various types of boilers, such as lean coal, bituminous coal, and lignite boilers, with flexible combustion methods including wall-mounted combustion and tangential combustion). In other words, both models of plasma generator 500 are widely used in coal-fired boiler bodies 00, and the specific model chosen can be selected based on actual conditions; this application does not impose specific limitations on this selection.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A plasma ignition system for a coal-fired boiler, characterized in that, include: A coal-fired boiler body (100) is provided with a plasma burner (101) connected to its furnace. A plasma generator (200) penetrates the coal-fired boiler body (100) and is connected to the plasma burner (101) for generating a high-temperature plasma jet and channeling the high-temperature plasma jet into the plasma burner (101). A coal mill (300) is provided, the coal outlet of which is connected to the plasma burner (101) via a pulverized coal conveying pipe (301). An air supply pipe (400) is connected to one end of the pulverized coal conveying pipe (301) near the coal outlet of the coal mill (300). A combustion-supporting pipe (500) passes through the coal-fired boiler body (100) and is connected to the furnace of the coal-fired boiler body (100) for introducing combustion-supporting gas into the furnace of the coal-fired boiler body (100).

2. The plasma ignition system for coal-fired boilers according to claim 1, characterized in that, The air supply pipe (400) is equipped with a first air volume regulating valve (401). A pulverized coal flow meter (3011) is installed on the pulverized coal conveying pipeline (301) between the coal mill (300) and the air supply pipe (400).

3. The plasma ignition system for coal-fired boilers according to claim 1, characterized in that, The end of the air supply pipe (400) away from the pulverized coal conveying pipe (301) is used to connect to the hot air source (4011), and a cold air pipe (402) is connected to it. The end of the cold air pipe (402) away from the air supply pipe is used to connect to the cold air source (4021). The air supply duct (400) is provided with a second air volume regulating valve (403) on the duct body between the hot air source (4011) and the cold air duct (402), and a third air volume regulating valve (4022) is provided on the cold air duct (402).

4. The plasma ignition system for coal-fired boilers according to claim 1, characterized in that, The end of the combustion-supporting pipe (500) away from the coal-fired boiler body (100) is connected to the hot air outlet of the air preheater (600). The heat exchange medium inlet of the air preheater (600) is connected to the steam outlet of the coal-fired boiler body (100) through the steam pipe (601). The heat exchange medium outlet of the air preheater (600) is connected to the water inlet of the economizer (700) through the condensate pipe (602).

5. The plasma ignition system for coal-fired boilers according to claim 4, characterized in that, A circulating water pump (6021) is installed on the condensate pipe (602).

6. The plasma ignition system for coal-fired boilers according to claim 1, characterized in that, There are multiple combustion-supporting pipes (500), which are connected to the furnace of the coal-fired boiler body (100) around the plasma generator (200). Each combustion-supporting pipe (500) forms a preset angle with the plasma burner (101). The preset included angle is an acute angle.

7. The plasma ignition system for coal-fired boilers according to claim 6, characterized in that, Each of the combustion-supporting pipes (500) is provided with a fourth air volume regulating valve (501).

8. The plasma ignition system for a coal-fired boiler according to any one of claims 1 to 7, characterized in that, An induced draft fan (800) is installed on the air supply pipe (400) near the pulverized coal conveying pipe (301) and on the combustion-supporting pipe (500).

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