A high-power plasma generator with an anti-carbon deposition cathode module

Abstract

The application discloses a kind of high-power plasma generators of anti-carbon deposition cathode module, belong to plasma generator technical field;The plasma generator includes cathode body stem and cathode head, and the surface of cathode head is coated with hafnium carbide composite coating formed by ceramic phase HfC and metal binder phase, and the thickness is 50 μm 200 μm.Cathode head and cathode body stem are detachably connected by thread.The driving mechanism drives anti-carbon deposition cathode to rotate at low speed at the rotating speed of 1020rpm by center transmission shaft.The application reconstructs the thermal physical properties of cathode surface by HfC coating, inhibits carbon deposition and corrosion;Utilize the self-cleaning of rotation centrifugal force, break the static environment of carbon deposition;Combined with modular quick-change structure, only replace cathode head can restore performance.The generator solves the problem that cathode is easy to carbon deposition and ablation under high volatile lignite condition, significantly prolongs the service life, and reduces maintenance cost.

Description

Technical Field

[0001] This invention belongs to the field of plasma generator technology and relates to a high-power plasma generator with an anti-carbon deposition cathode module. Background Technology

[0002] Plasma ignition technology, with its significant advantages of oil-free start-up and low pollutant emissions, has become the mainstream technology for cold start-up and stable combustion at low loads in thermal power plant boilers, especially meeting the industry's needs for cost reduction, efficiency improvement, and green and low-carbon development. However, in practical engineering applications, the failure rate of the cathode components of plasma generators remains high when burning high-volatile lignite, and the carbon deposition-ablation coupling failure problem has become the core bottleneck restricting the long-term stable operation of this technology.

[0003] From the failure mechanism analysis, lignite rapidly releases large amounts of volatiles such as methane, hydrogen, and tar vapor during the initial stage of plasma ignition. These components undergo multiple physicochemical changes in the high-temperature field of the plasma arc: On the one hand, heavy hydrocarbons condense and polymerize in the low-temperature region near the cathode surface, gradually forming a porous carbon coke layer with extremely poor conductivity. This deposit layer distorts the electric field distribution on the cathode surface, inducing arc drift and a sudden increase in local current density, ultimately causing the cathode tip to melt. On the other hand, the fly ash produced by lignite combustion contains alkali metals such as sodium and potassium, as well as corrosive elements such as sulfur and chlorine. Under high-temperature conditions, these react chemically with conventional cathode materials such as tungsten-based and copper alloys, generating low-melting-point eutectics or hard deposits, triggering thermal corrosion and chemical erosion. Simultaneously, the carbon coke layer and corrosion products disrupt the original heat conduction path of the cathode, leading to local heat accumulation, further accelerating the material ablation process, forming a vicious cycle of carbon buildup aggravating corrosion and corrosion promoting carbon buildup.

[0004] To address the aforementioned issues, the industry currently primarily employs passive protection measures such as flue gas filtration and inert gas purging. Some improvement schemes attempt to optimize the cathode geometry or replace it with high-temperature resistant precious metals such as tantalum and molybdenum. However, all of these solutions have significant limitations: First, passive protection can only reduce the contact of pollutants with the cathode and cannot block the physicochemical reaction pathways of heavy hydrocarbon condensation and deposition. The carbon buildup problem can only be alleviated temporarily and cannot be eliminated at its root. Second, the purging system requires a dedicated gas source, pipelines, and control unit, resulting in a complex system structure that not only increases energy consumption but also raises the workload of daily operation and maintenance. Third, while simply relying on material upgrades can slightly increase the upper limit of temperature resistance, it cannot resist the complex erosion under high-volatile lignite conditions. The overall service life of the cathode is still insufficient to meet the continuous operation requirements of the unit, and the cost of replacing the entire cathode is high, making it uneconomical.

[0005] In summary, existing plasma cathode technology is difficult to adapt to the ignition conditions of high-volatile lignite. There is an urgent need to develop a systematic solution that integrates material modification, structural optimization and active cleaning to overcome the protection limitations of traditional technologies, achieve long service life and high reliability of cathode components, and ensure the safe and stable commissioning of power plant boilers. Summary of the Invention

[0006] The purpose of this invention is to provide a high-power plasma generator with an anti-carbon-deposited cathode module, so as to solve the technical problem of severe carbon deposition on the cathode in the prior art, which affects its service life and reliable operation.

[0007] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a high-power plasma generator with an anti-carbon deposition cathode module, comprising an anode and an anti-carbon deposition cathode mounted on an insulator, wherein the anode and the anti-carbon deposition cathode cooperate to form a discharge channel; the anti-carbon deposition cathode includes a cathode body rod and a cathode head, wherein the cathode head is disposed on the cathode body rod near the anode; the cathode head is connected to one end of a central drive shaft, and the other end of the central drive shaft passes through the cathode body rod and is connected to a drive mechanism.

[0008] Furthermore, the surface of the cathode head is coated with an HfC composite coating.

[0009] Furthermore, the HfC composite coating is composed of a ceramic phase HfC and a metallic binder phase.

[0010] Furthermore, the thickness of the HfC composite coating is 50μm-200μm.

[0011] Furthermore, the connection between the cathode head and the cathode body rod is a detachable connection.

[0012] Furthermore, the cathode head and the cathode body rod are connected by threads.

[0013] Furthermore, the driving mechanism is a rotary motor, which can drive the anti-carbon deposition cathode to rotate.

[0014] Furthermore, the rotational speed of the anti-carbon deposition cathode is 10 rpm - 20 rpm.

[0015] Furthermore, the anode and the anti-carbon deposition cathode are coaxially arranged.

[0016] Furthermore, the material used to prepare the anti-carbon deposition cathode is selected from tungsten, molybdenum, and copper alloys.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a high-power plasma generator with an anti-carbon deposition cathode module. The cathode head and cathode body rod adopt a split threaded connection design, constructing a modular quick-change system. During maintenance, only small consumable parts need to be replaced to restore equipment performance, greatly reducing the maintenance cost throughout the entire life cycle. A drive mechanism drives the anti-carbon deposition cathode to rotate, and the centrifugal force effect achieves dynamic protection of working and cleaning simultaneously, completely breaking the static environment for carbon deposition formation, effectively stripping molten ash particles and carbon coke layers, and eliminating arc drift and instability caused by carbon deposition. The hafnium carbide (HfC) composite coating on the cathode head surface, with its high melting point of over 3900℃ and excellent thermal conductivity, effectively reconstructs the surface thermophysical properties, not only significantly improving the resistance to thermal shock and chemical corrosion, but also reducing the cathode ablation rate by 30%-50%. Ultimately, this significantly improves the success rate of oil-free ignition and the operational safety of high-volatile lignite boilers. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a high-power plasma generator with an anti-carbon deposition cathode module according to the present invention.

[0020] Wherein: 1-Anode; 2-Anti-carbon deposition cathode; 21-Cathode body rod; 22-Cathode head; 23-HfC composite coating; 24-Central drive shaft; 3-Insulator; 4-Drive mechanism. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1This invention discloses a high-power plasma generator with an anti-carbon deposition cathode module, comprising an anode 1 and an anti-carbon deposition cathode 2 mounted on an insulator 3, wherein the anode 1 and the anti-carbon deposition cathode 2 cooperate to form a discharge channel; the anti-carbon deposition cathode 2 includes a cathode body rod 21 and a cathode head 22, wherein the cathode head 22 is disposed on the cathode body rod 21 near the anode 1; the cathode head 22 is connected to one end of a central drive shaft 24, and the other end of the central drive shaft 24 passes through the cathode body rod 21 and is connected to a drive mechanism 4, thereby driving the cathode head 22 to rotate at a low speed along the axis during operation; this structure is... The drive mechanism 4 drives the central drive shaft 24 and the cathode head 22 to rotate at a constant speed. The centrifugal force effect is used to actively peel off the carbon coke and molten ash particles deposited on the surface of the cathode head 22. At the same time, it can be used in conjunction with a conventional water cooling jacket to force-cool the cathode body rod 21 and the central drive shaft 24. This not only breaks the static thermal boundary layer formed by carbon deposits, but also effectively solves the problem of carbon deposit-ablation coupling failure under high volatile lignite conditions. While ensuring arc stability and cathode cooling efficiency, it significantly reduces the replacement cost and maintenance difficulty of vulnerable parts, and realizes long-term stable operation of the plasma generator under harsh conditions.

[0028] In one feasible embodiment of the present invention, the surface of the cathode head 22 is coated with an HfC composite coating 23. The HfC composite coating 23 is composed of a ceramic phase HfC and a metal binder phase. The thickness of the HfC composite coating 23 is 50 μm-200 μm. This coating, serving as a functional layer to block corrosive media and optimize thermal management, is designed according to a ceramic-metal composite system. It consists of a uniform mixture of a high-melting-point ceramic phase (HfC) and a metal binder phase with good toughness (such as a nickel-based alloy or a tungsten-cobalt alloy). The ceramic phase provides an ultra-high melting point exceeding 3900℃ and excellent thermal shock resistance, while the metal binder phase significantly improves the interfacial bonding strength between the coating and the tungsten-based or copper alloy substrate, effectively preventing coating peeling under thermal cycling conditions. At the same time, the thickness of this HfC composite coating 23 is strictly controlled within the range of 50μm-200μm. This thickness range ensures that the coating has sufficient thermal conductivity to quickly dissipate the concentrated heat at the root of the arc, preventing overheating and ablation of the substrate, while also balancing the internal stress of the coating. This prevents brittle cracking due to excessive thickness or insufficient wear and corrosion resistance due to insufficient thickness, thereby fundamentally inhibiting the condensation and deposition of heavy hydrocarbons and alkali metal chemical corrosion, and significantly extending the service life of the cathode head under harsh conditions.

[0029] In one feasible embodiment of the present invention, the connection between the cathode head 22 and the cathode body rod 21 is a detachable connection. Preferably, the cathode head 22 and the cathode body rod 21 are connected by threads. This split-type threaded connection structure allows for maintenance without replacing the entire cathode; only the worn cathode head 22 needs to be unscrewed to complete the replacement of the core component. While ensuring the reliability of the electrical connection, it greatly simplifies the maintenance process and significantly reduces the total life-cycle maintenance cost of the equipment.

[0030] In one feasible embodiment of the present invention, the driving mechanism 4 is a rotary motor, which drives the anti-carbon deposition cathode 2 to rotate. The rotation speed of the anti-carbon deposition cathode 2 is 10 rpm - 20 rpm. This rotation speed range can generate centrifugal force sufficient to overcome the adhesion of the carbon layer to achieve real-time peeling of surface deposits, avoiding incomplete carbon removal due to excessively low rotation speed or arc drift and arc breakage due to excessively high rotation speed. It can also control the linear velocity of the outer edge of the cathode head 22 within a reasonable threshold, preventing additional wind resistance loss and mechanical vibration caused by high-speed rotation; thus significantly improving the reliability and safety of equipment operation.

[0031] In one feasible embodiment of the present invention, the anode 1 and the anti-carbon deposition cathode 2 are coaxially arranged to ensure that they maintain strict concentricity during assembly and operation, thereby forming a stable and uniform annular discharge gap in the axial direction. This avoids electric field distortion, arc skew, and local overheating caused by eccentricity, thus ensuring stable ignition and continuous combustion of the plasma arc. The anti-carbon deposition cathode 2 is made of a material selected from tungsten, molybdenum, and copper alloys. Tungsten and molybdenum, as high-melting-point refractory metals, are suitable for high-power, high-load conditions due to their extremely high melting points and excellent electron emission performance, while copper alloys, with their excellent thermal conductivity, are suitable for low-to-medium power scenarios requiring rapid heat dissipation. Moreover, the above materials are all well-known mature electrode materials in the art, possessing good processing performance and cost-effectiveness. By combining precise control of coaxiality with the selection of electrode materials suitable for the operating conditions, not only is abnormal electrode erosion caused by arc instability effectively suppressed, but the energy density and jet stiffness of the plasma are also significantly improved, ultimately ensuring the high-efficiency and long-life operation of the generator in the high-volatile lignite ignition environment.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-power plasma generator with an anti-carbon deposition cathode module, characterized in that, It includes an anode (1) and an anti-carbon deposition cathode (2) mounted on an insulator (3), the anode (1) and the anti-carbon deposition cathode (2) cooperate to form a discharge channel; the anti-carbon deposition cathode (2) includes a cathode body rod (21) and a cathode head (22), the cathode head (22) is disposed on the cathode body rod (21) near the anode (1); the cathode head (22) is connected to one end of a central drive shaft (24), and the other end of the central drive shaft (24) passes through the cathode body rod (21) and is connected to a drive mechanism (4).

2. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 1, characterized in that, The surface of the cathode head (22) is coated with an HfC composite coating (23).

3. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 2, characterized in that, The HfC composite coating (23) is composed of ceramic phase HfC and metal binder phase.

4. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 2, characterized in that, The thickness of the HfC composite coating (23) is 50μm-200μm.

5. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 1, characterized in that, The connection between the cathode head (22) and the cathode body rod (21) is a detachable connection.

6. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 5, characterized in that, The cathode head (22) and the cathode body rod (21) are connected by threads.

7. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 1, characterized in that, The driving mechanism (4) is a rotary motor, which can drive the anti-carbon deposition cathode (2) to rotate.

8. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 7, characterized in that, The rotational speed of the anti-carbon deposition cathode (2) is 10 rpm - 20 rpm.

9. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 1, characterized in that, The anode (1) and the anti-carbon deposition cathode (2) are arranged coaxially.

10. A high-power plasma generator with an anti-carbon deposition cathode module according to claim 1, characterized in that, The material used to prepare the anti-carbon deposition cathode (2) is selected from tungsten, molybdenum and copper alloys.

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