Plasma generator cathode inner core with bluff body turbulence cooling structure

Abstract

The utility model discloses a plasma generator cathode inner core with a bluff body turbulence cooling structure, and belongs to the technical field of plasma generators. The cathode inner core comprises a bluff body turbulent flow cathode head, an emitter and a cathode seat; the bluff body turbulent flow cathode head is an integrated special-shaped structural body, the bluff body turbulent flow cathode head and the cathode seat are connected together to form a deep cup-shaped structure with one end provided with a circular opening and the other end provided with a horn opening, and the length-diameter ratio of an inner hole of the cathode seat to an inner hole of the connecting end of the bluff body turbulent flow cathode head is 5-15 times; and the emitter is embedded in the center of an inner hole of the bluff body turbulence cathode head. The plasma generator is simple in structure, small in size, low in cost, convenient to replace and maintain, high in plasma temperature and reliable in operation, the working temperature of the cathode inner core can be further reduced, and the service life of the cathode inner core can stably reach more than 1200 hours.

Description

Technical Field

[0001] This utility model relates to the field of plasma generator technology, and in particular to a plasma generator cathode core with a blunt body turbulent cooling structure suitable for plasma ignition of pulverized coal boilers. Background Technology

[0002] In today's technological field, plasma technology is at the forefront and developing rapidly. It has been widely applied to numerous industrial sectors. For example, in pulverized coal combustion, plasma energy excitation enables more efficient combustion and improves energy utilization efficiency; in hazardous waste treatment and waste incineration, the high-temperature characteristics of plasma are used to harmlessly and in reduced-volume treatment of hazardous waste and garbage, effectively solving environmental pollution problems; in steel cutting, the high energy density of plasma enables precise and efficient cutting of steel, improving processing accuracy and production efficiency; in metal smelting, it promotes metal purification and refining, improving metal properties; and it also plays a crucial role in surface coating and nanomaterial manufacturing, enhancing product quality and performance.

[0003] The cathode, as a core component of a plasma generator, is undeniably crucial. On one hand, it endures harsh conditions such as high temperatures and high-energy impacts during operation, making it a vulnerable part. On the other hand, its complex manufacturing process and high material costs make it a key focus for extending its lifespan and reducing costs. In modern enterprises pursuing cost reduction and efficiency improvement, optimizing cathode performance and lowering its wear and tear costs are of paramount importance.

[0004] Currently, some design problems exist in the cathode core cooling structure of existing technologies. In patent publication number CN107529269A, the cooling water-facing surface of the cathode head only has a conical structure. When the cooling water flows through the conical surface, the water flow is relatively stable, making it difficult to create turbulence. Turbulence can enhance the heat transfer coefficient between the fluid and the wall, improving cooling efficiency. This cooling structure, which cannot create turbulence, results in unsatisfactory cooling performance, failing to meet the cooling performance requirements of the cathode under high-intensity operating conditions, thus affecting the overall performance and service life of the plasma generator. Therefore, developing a plasma generator cathode core structure that can create turbulence and improve cooling efficiency has significant practical importance and market demand. Summary of the Invention

[0005] Technical problem: The purpose of this utility model is to overcome the shortcomings of the existing technology and provide a plasma generator cathode core with a blunt body turbulent cooling structure that has a simple structure and good performance.

[0006] Technical Solution: This utility model discloses a plasma generator cathode core with a bluff body turbulent cooling structure, comprising a bluff body turbulent cathode head, an emitter, and a cathode seat; the bluff body turbulent cathode head is an integral irregular structure, with one side of its outer surface being conical and the other side being cylindrical, and a diameter of [missing information] is opened on the conical end face of the bluff body turbulent cathode head. Φ1 The hollow inner cylindrical opening has a circular arc-shaped groove at its bottom, and a convex, blunt cone with a spherical groove at its top protrudes within the circle enclosed by the arc-shaped groove; the circumference at the junction of the cylinder and the cone is evenly distributed with a diameter of Φ2 Multiple interconnected cones have through holes inside cylindrical openings, and the end face of the cylinder has a diameter of [missing information]. Φ3 The hollow inner cylindrical opening has a diameter of Φ3 Larger than diameter Φ1 The hollow inner cylindrical opening has a cone with a flat top protruding from the center of the bottom. A cylindrical blind hole is opened in the center of the cone. The emitter is embedded in the cylindrical blind hole. The cathode seat is a cylindrical tubular body with the same inner and outer diameters as the diameter of one side of the blunt body turbulent cathode head column. One end of the cylindrical tubular body is a circular opening and the other end is a flared opening. The circular opening end of the cylindrical tubular body is connected to the circular opening end of the side end face of the blunt body turbulent cathode head column to form a hollow inner cylindrical deep cup-shaped structure with a flared opening. The length-to-diameter ratio of the inner hole of the cathode seat (3) to the inner hole of the connection end of the blunt body turbulent cathode head (1) is 5 to 15 times.

[0007] The cone angle α of the cone on one side of the outer surface of the blunt body turbulent cathode head is 10 to 70°.

[0008] The diameter of the hollow inner cylindrical opening on the conical side end face of the blunt body turbulent cathode head Φ1 It is 12-20mm.

[0009] The distance D1 from the conical side end face of the blunt body turbulent cathode head to the blunt body end face of the frustum with a top spherical groove is 3 to 8 mm.

[0010] The distance D from the conical side end face of the blunt body turbulent cathode head to the center of the circumferentially distributed through holes at the junction of the cylinder and the cone is 12-15 mm.

[0011] The diameter Φ2 of the circular through holes evenly distributed around the circumference at the junction of the column and cone of the blunt body turbulent cathode head is 1 to 5 mm, and the number of circular through holes is 4 to 20.

[0012] The radius SR of the spherical groove on the blunt body of the blunt body with a spherical groove inside the hollow cylindrical opening on the conical side of the blunt body is 2 to 6 mm, and the cone angle b of the frustum is 10 to 70°.

[0013] The height D2 of the truncated cone with a flat top inside the hollow cylindrical opening on the cylindrical side of the blunt body turbulent cathode head is 3-8 mm, and the cone angle c is 20-90°.

[0014] The emitter and the blunt body turbulent cathode head are fixed by brazing or interference fit, and the blunt body turbulent cathode head and the cathode seat are fixed by welding or threaded connection.

[0015] Beneficial Effects: By employing the above technical solution and utilizing a specially designed blunt body structure, the cooling water flow across the left-side water-facing surface of the cathode head is disturbed, entering a turbulent state in a very short time. This increases the speed and efficiency of heat transfer, allowing the heat generated by the emitter to be carried away by the cooling water more quickly through the cathode head, thereby enhancing the cooling effect and improving the emitter's lifespan. Computer simulations show that the cathode core with the above structure has excellent cooling performance. Its simple structure, high plasma temperature, and reliable operation can further reduce the operating temperature of the cathode core, and the cathode core's lifespan can stably reach over 1200 hours. Compared with existing technologies, this invention features a novel structure. By adding a blunt body to the water-facing surface of the turbulent cathode head, the cooling water around the blunt body produces the following effects:

[0016] 1) Enhanced Disturbance: Utilizing a bluff body to create disturbance in fluid flow disrupts the stability of the boundary layer, promoting more thorough mixing between the low-velocity fluid within the boundary layer and the high-velocity fluid in the mainstream region. This mixing increases the speed and efficiency of heat transfer, allowing heat from the bluff body surface to be carried away more quickly, thus achieving cooling.

[0017] 2) Increase heat exchange area: The presence of a bluff body increases the contact area between the fluid and the surface of the object. According to the principle of heat transfer, the increase in heat exchange area is conducive to heat transfer. More heat can be transferred from the bluff body to the fluid through the increased contact area and then carried away by the fluid.

[0018] 3) Changes in flow field distribution: The bluff body alters the flow field structure of the fluid, creating complex flow fields around it, such as vortices and wakes. These special flow field structures can enhance fluid disturbance and convective heat transfer capabilities, thereby improving cooling efficiency.

[0019] 4) This utility model has a relatively simple structure, small size, low cost, and is easy to replace and maintain, and has wide applicability and considerable economic benefits. Attached Figure Description

[0020] Figure 1 This is a cross-sectional structural diagram of the present invention.

[0021] Figure 2 This is a cross-sectional view of the present invention after it has been installed on a plasma generator.

[0022] Figure 3 This is a schematic diagram of the internal and external cooling water flow direction of the blunt body turbulent cathode head structure of this utility model.

[0023] Figure 4 This is a three-dimensional structural diagram of the blunt body side of the blunt body turbulent cathode head of this utility model.

[0024] In the figure: 1- Blunt body turbulent cathode head, 2-Emitter, 3-Cathode seat. Detailed Implementation

[0025] An embodiment of the present invention will be further described below with reference to the accompanying drawings:

[0026] like Figure 1 As shown, the plasma generator cathode core with a blunt-body turbulent cooling structure of this invention mainly consists of a blunt-body turbulent cathode head 1, an emitter 2, and a cathode seat 3. The blunt-body turbulent cathode head 1 is an integral irregular-shaped structure. One side of the outer surface of the blunt-body turbulent cathode head 1 is conical, and the other side is cylindrical. A diameter of [missing information] is opened on the conical side end face of the blunt-body turbulent cathode head 1. Φ1 The hollow inner cylindrical opening has a circular arc-shaped groove at its bottom, and a convex, blunt cone with a spherical groove at its top protrudes within the circle enclosed by the arc-shaped groove; the circumference at the junction of the cylinder and the cone is evenly distributed with a diameter of Φ2 Multiple interconnected cones have through holes inside cylindrical openings, and the end face of the cylinder has a diameter of [missing information]. Φ3 The hollow inner cylindrical opening has a diameter of Φ3 Larger than diameter Φ1 The hollow inner cylindrical opening has a truncated cone with a flat top at the center of its bottom. A cylindrical blind hole is opened at the center of the truncated cone, and the emitter 2 is embedded in the cylindrical blind hole. The cathode seat 3 is a cylindrical tubular body with the same inner and outer diameters as the diameter of one side of the blunt body turbulent cathode head 1. One end of the cylindrical tubular body is a circular opening, and the other end is a flared opening. The circular opening end of the cylindrical tubular body is connected to the circular opening end of the side end face of the blunt body turbulent cathode head 1, forming a hollow inner cylindrical deep cup-shaped structure with a flared opening, that is, a complete cathode core structure. The length-to-diameter ratio of the inner hole of the cathode seat 3 to the inner hole of the connection end of the blunt body turbulent cathode head 1 is 5 to 15 times.

[0027] The cone angle α of the outer conical surface at the left end of the blunt body turbulent cathode head 1 ranges from 10° to 70°. The diameter Φ1 of the hollow cylindrical structure at the left end of the blunt body turbulent cathode head 1 is 12° to 20°. The distance D1 from the left end face of the blunt body turbulent cathode head 1 to the left end face of the frustum-shaped blunt body with a spherical groove is 3° to 8°. The distance D from the left end face of the blunt body turbulent cathode head 1 to the center of the circumferentially distributed circular through holes is 12° to 15°. The diameter Φ2 of the circumferentially distributed circular through holes at the left end of the blunt body turbulent cathode head 1 is 1° to 5°, and the number of circular through holes is 4° to 20. The radius SR of the spherical groove on the frustum-shaped blunt body with a spherical groove at the left end of the blunt body turbulent cathode head 1 is 2° to 6°, and the cone angle b of the frustum-shaped blunt body ranges from 10° to 70°. The blunt-body turbulent cathode head 1 has a raised, flat-topped truncated cone with a height D2 of 3–8 mm and a cone angle c ranging from 20–90°. The emitter 2 is made of pure silver, pure hafnium, pure tungsten, or an alloy of these three materials in any proportion, or a novel zirconium-titanium-aluminum-scandium alloy, offering a wider range of material options compared to previous emitters. The cathode holder 3 is made of pure silver, pure copper, or an alloy of these two materials in any proportion. The emitter 2 and the blunt-body turbulent cathode head 1 are connected and fixed by brazing or interference fit, while the blunt-body turbulent cathode head 1 and the cathode holder 3 are fixed by welding or threaded connection. Compared to the previous integral structure of the deep-cup-shaped cathode core, the split structure is more flexible, allowing for the individual replacement of damaged blunt-body turbulent cathode head 1 and cathode holder 3 as needed.

[0028] Specific embodiment: The present invention is installed at the axial center position near the front nozzle of the plasma generator, such as... Figure 2 Figure 3 As shown, after the plasma generator starts working, the air between the anode and cathode is continuously ionized, generating a plasma arc. Electrons are continuously emitted from the emitter 2 of the cathode head 1 and eventually fall onto the inner surface of the anode. Figure 2 The thick black line represents the trajectory of electrons. When a large number of electrons fly together, it forms a continuous electric arc. Figure 2 For ease of understanding, only one electric arc is shown in the diagram, but there can actually be N electric arcs. The cooling water entering from the central channel of the plasma generator is diverted and reversed by the inner core of the plasma generator cathode with the bluff body turbulent cooling structure of this invention. When the cooling water reaches the bluff body turbulent cathode head 1, part of the cooling water enters the hollow inner cylindrical opening on the conical end face of the bluff body 1, and then flows back after passing through the frustum-shaped bluff body with a spherical groove at the top and the arc-shaped groove; a ring of evenly distributed circular through holes is located near the bottom of the cone on the outer surface of the left end. Figure 4As shown, a circular through-hole is perpendicular to and connected to the hollow cylindrical structure. Part of the cooling water flows out of the bluff body turbulent cathode head 1 through the circular through-hole and enters the cooling water channel, continuing to flow towards the right side of the cathode seat 3. A truncated cone with a flat top protrudes from the center of the bottom of the cylindrical structure on the outer right end of the bluff body turbulent cathode head 1. A cylindrical emitter 2 is embedded in the center of the truncated cone. The end face of the emitter 2 protrudes, and compressed air entering the cathode seat 3 returns along the surface of the truncated cone after reaching its bottom, converging axially near the emitter end face, thus better constraining the plasma arc and preventing arc ablation of the bluff body turbulent cathode head 1. The cathode seat 3 is a tubular body with a circular opening at one end and a flared opening at the other. The left circular opening end is connected to the right circular opening end of the bluff body turbulent cathode head 1, forming a complete cathode core structure.

[0029] The addition of the blunt body in this invention creates a turbulent flow effect in the cooling water flowing over the outer side of the turbulent cathode head.

[0030] At the microscopic level: In turbulent flow, strong random pulsations exist within the fluid, and the velocities of fluid particles change rapidly and irregularly in all directions. This pulsation greatly enhances heat conduction and convection between fluid molecules. During the pulsation process, fluid particles continuously exchange heat with the surrounding fluid and the surface of the object being cooled, accelerating the transfer of heat from the object to the fluid.

[0031] At the macroscopic level: Turbulence can disrupt the boundary layer formed between the fluid and the surface of the object being cooled. The boundary layer is usually a relatively static fluid layer that hinders heat transfer. However, the strong disturbances of turbulence can thin or even completely destroy the boundary layer, allowing the surface of the high-temperature object to come into more direct contact with the cooling fluid, thereby increasing the heat exchange coefficient and improving cooling efficiency.

Claims

1. A plasma generator cathode core with a bluff body turbulent cooling structure, characterized in that: It includes a blunt body turbulent cathode head (1), an emitter (2), and a cathode seat (3); the blunt body turbulent cathode head (1) is an integral irregular structure, with one side of the outer surface of the blunt body turbulent cathode head (1) being conical and the other side being cylindrical, and the conical end face of the blunt body turbulent cathode head (1) having a diameter of Φ1 The hollow inner cylindrical opening has a circular arc-shaped groove at its bottom, and a convex, blunt cone with a spherical groove at its top protrudes within the circle enclosed by the arc-shaped groove; the circumference at the junction of the cylinder and the cone is evenly distributed with a diameter of Φ2 Multiple interconnected cones have through holes inside cylindrical openings, and the end face of the cylinder has a diameter of [missing information]. Φ3 The hollow inner cylindrical opening has a diameter of Φ3 Larger than diameter Φ1 The hollow inner cylindrical opening has a truncated cone with a flat top at the center of the bottom. A cylindrical blind hole is opened in the center of the truncated cone. The emitter (2) is embedded in the cylindrical blind hole. The cathode seat (3) is a cylindrical tubular body with the same inner and outer diameter as the diameter of one side of the blunt body turbulent cathode head (1). One end of the cylindrical tubular body is a circular opening and the other end is a flared opening. The circular opening of the cylindrical tubular body is connected to the circular opening end of the side end face of the blunt body turbulent cathode head (1) to form a hollow inner cylindrical deep cup-shaped structure with a flared opening. The length-to-diameter ratio of the inner hole of the cathode seat (3) to the inner hole of the connection end of the blunt body turbulent cathode head (1) is 5 to 15 times.

2. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The cone angle α of the cone on one side of the outer surface of the blunt body turbulent cathode head (1) is 10 to 70°.

3. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The diameter of the hollow inner cylindrical opening on the conical side end face of the blunt body turbulent cathode head (1) Φ1 It is 12-20mm.

4. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The distance D1 from the conical side end face of the blunt body turbulent cathode head (1) to the blunt body end face of the frustum with a top spherical groove is 3 to 8 mm.

5. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The distance D from the cone-shaped end face of the blunt body turbulent cathode head (1) to the center of the circumferentially distributed through holes at the junction of the cylinder and the cone is 12-15 mm.

6. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The diameter Φ2 of the circular through holes evenly distributed around the circumference at the junction of the column and the cone of the blunt body turbulent cathode head (1) is 1 to 5 mm, and the number of circular through holes is 4 to 20.

7. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The radius SR of the spherical groove on the blunt body of the blunt body with a spherical groove inside the hollow cylindrical opening on the conical side of the blunt body (1) is 2 to 6 mm, and the cone angle b of the frustum is 10 to 70°.

8. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The blunt body turbulent cathode head (1) has a truncated cone with a flat top, whose height D2 is 3-8 mm and whose cone angle c is 20-90°. The hollow inner cylindrical opening on the cylindrical side of the cylinder is convex.

9. The plasma generator cathode core with a bluff body turbulent cooling structure according to claim 1, characterized in that: The emitter (2) and the blunt body turbulent cathode head (1) are fixed by brazing or interference fit, and the blunt body turbulent cathode head (1) and the cathode seat (3) are fixed by welding or threaded connection.

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