Plasma melting furnace and use method thereof

Abstract

The invention discloses a plasma melting furnace and a using method thereof, and belongs to the technical field of incineration hazardous waste treatment. The plasma melting furnace comprises a furnace body, and a plasma anode and a plasma cathode opposite to the plasma anode are arranged in the furnace body; the furnace body is further provided with a feeding mechanism, the feeding mechanism and the plasma cathode are staggered, and a material outlet of the feeding mechanism is aligned with the plasma coverage area. The feeding mechanism is used for conveying materials to a plasma coverage area. The main purpose of the invention is that the material directly falls into a plasma sweeping range, namely a plasma coverage area, through the feeding mechanism, the material can be quickly fused, and fine powder can be condensed into liquid drops within a short time, so that the fusion efficiency is improved, the fusion disposal amount is increased, and secondary ash is reduced.

Description

Technical Field

[0001] This invention relates to the field of hazardous waste incineration technology, and more specifically, to a plasma melting furnace and its usage method. Background Technology

[0002] In large-scale plasma melting furnaces, materials directly swept by plasma can melt rapidly in an ultra-high temperature and high-density thermal environment exceeding 5000℃. Large organic molecules such as dioxins are instantly broken down into smaller molecules, increasing the processing capacity per unit volume of the furnace while avoiding the release of toxic and harmful gases. Materials that cannot be directly swept by plasma are mainly heated through the radiant heat of the plasma and the conductive heat of the molten liquid. However, the heating rate and effect are far inferior to direct plasma sweeping, resulting in poor melting performance. Therefore, by maximizing the amount of material within the plasma sweeping range without causing arc interruption, melting efficiency and energy utilization can be improved, as well as the treatment effect on hazardous organic waste.

[0003] Large plasma melting furnaces can have a furnace body diameter of up to 6 meters, but the area directly scanned by the plasma cathode, i.e., the plasma coverage area, is less than 2 meters in diameter. Currently, most melting furnaces in China use vertically downward feeding, such as the melting furnace disclosed in Chinese patent CN219140789U. Figure 1 As shown, the negative electrode of the plasma arc is connected to the furnace body through electrode holes. Material falls vertically into the furnace through the feed inlet and melts at high temperatures. However, this vertically downward feeding method results in a prolonged residence time of the material in the gas phase space. Some fine powder is directly drawn into the exhaust gas system through the flue gas outlet, becoming fly ash and increasing the amount of secondary hazardous waste. Furthermore, material may accumulate outside the area directly swept by the negative electrode of the plasma arc, preventing timely melting and affecting melting efficiency.

[0004] Another method is wall-feeding, such as the plasma melting furnace disclosed in Chinese patent CN219140789U. Figure 2 As shown, the plasma generator has two graphite electrodes, serving as the cathode and anode. The feed inlet is located on the furnace wall of the melting zone within the furnace body. The material to be processed enters the melting furnace along the furnace wall through the feed inlet and melts into a liquid. However, by feeding along the wall, the material adheres to the furnace wall, causing some of the molten material to stick to the wall, resulting in irregular thickening of the furnace wall. This reduces the effective processing space within the furnace, increases melting dead zones, and is detrimental to the long-term use of the melting furnace. Furthermore, because the material enters the melting furnace along the furnace wall, it is difficult for the material to fall into the high-temperature zone generated by the plasma generator, thus hindering rapid melting. This results in a slow melting rate, low melting capacity per unit cross-section, and low working efficiency of the melting furnace.

[0005] Therefore, there is an urgent need for a large-diameter plasma melting furnace in which materials fall directly into the plasma sweeping range, i.e., the plasma coverage area, through the feeding mechanism. The materials can melt rapidly, and fine powder can be agglomerated into droplets in a short time, thereby increasing melting efficiency, increasing melting capacity, and reducing secondary ash. Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plasma melting furnace, which aims to solve the problems of slow melting speed, low melting efficiency, and inability to handle dust in a timely and effective manner caused by the vertical downward or along the furnace wall feeding method of plasma melting furnace.

[0008] Technical solution

[0009] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0010] The present invention provides a plasma melting furnace, comprising a furnace body, wherein a plasma anode and a plasma cathode disposed opposite to the plasma anode are disposed within the furnace body;

[0011] The furnace body is also equipped with a feeding mechanism, which is offset from the plasma cathode, and the material outlet of the feeding mechanism is aligned with the plasma coverage area.

[0012] The feeding mechanism is used to transport materials into the plasma coverage area.

[0013] Furthermore, the plasma anode is located at the lower end of the furnace body, and the plasma cathode is located at the upper end of the furnace body;

[0014] The feeding mechanism is a spiral feed tube, which is located at the upper end of the furnace body. The spiral feed tube is inclined, and the material outlet of the spiral feed tube is aligned with the plasma coverage area.

[0015] Furthermore, there are multiple spiral feed tubes, which are evenly arranged in a ring around the plasma cathode.

[0016] The angle between the spiral feed tube and the plasma cathode is α, where α is 30° to 60°.

[0017] Furthermore, the distance L1 between the inlet end of the spiral feed tube and the plasma cathode is 0.8–1.2 m.

[0018] Furthermore, the length L2 of the spiral feed pipe extending into the furnace body is 0.5 to 0.9 m.

[0019] Furthermore, the distance between the outlet end of the spiral feed pipe and the end of the spiral blade is L3, where L3 ≥ 0.3m.

[0020] Furthermore, an inert gas is provided inside the spiral feed tube, and the pressure of the inert gas inside the spiral feed tube is greater than the gas pressure inside the furnace. This is used to enable the material to obtain an initial velocity at the material outlet of the spiral feed tube.

[0021] Furthermore, the difference between the pressure inside the melting furnace and the pressure of the inert gas is Y, where Y is -200 to 0 Pa.

[0022] Furthermore, the initial velocity of the material is 10–30 m / s, so that the material falls into the plasma coverage area.

[0023] Furthermore, the outer wall of the spiral feed tube is equipped with a water-cooling jacket for cooling the spiral feed tube.

[0024] The present invention also provides a method of using the plasma melting furnace described above:

[0025] The plasma cathode and plasma anode, which are positioned opposite each other, are opened to form a plasma coverage area;

[0026] After being sealed with nitrogen, the material gains initial velocity through the inclined spiral feed pipe that extends into the furnace body and falls into the plasma coverage area.

[0027] Adjust the angle α between the spiral feed tube and the plasma cathode, the length L2 of the spiral feed tube extending into the furnace, the rotation speed of the spiral blades, and the nitrogen pressure to ensure that materials of different masses fall into the plasma coverage area.

[0028] The materials are melted into molten glass and molten alloy, with the molten glass in the upper layer and the molten alloy in the lower layer; both the molten glass and the molten alloy are recycled.

[0029] The flue gas generated from the melting of materials is sent to the combustion chamber.

[0030] Beneficial effects

[0031] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0032] (1) The material outlet of the feeding mechanism of the present invention is aligned with the plasma coverage area and the material is transported to the plasma coverage area. Since the plasma coverage area has ultra-high temperature and high density of thermal energy, the material will melt rapidly after falling into the plasma coverage area. The fine particles such as dust in the material will also quickly condense into droplets, which improves the melting efficiency and material disposal volume, and also reduces secondary ash to facilitate subsequent dust removal and other treatments.

[0033] (2) The feeding mechanism of the present invention is a spiral feeding pipe that extends into the furnace body at an incline. The pressure difference between the spiral blades of the spiral feeding pipe and the pressure of the inert gas and the pressure inside the furnace body gives the material an initial velocity and enables it to fall into the plasma coverage area for rapid melting. Moreover, the falling point of the material can be controlled by adjusting the inclination angle of the spiral feeding pipe, the depth of its insertion into the furnace, the spiral rotation speed, and the nitrogen pressure, so as to meet the requirements of conveying different types or qualities of materials to the plasma coverage area and achieving rapid melting of materials. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a partial structure of an existing melting furnace;

[0035] Figure 2 This is a schematic diagram of another existing melting furnace structure;

[0036] Figure 3 This is a schematic diagram of a plasma melting furnace structure according to this application;

[0037] Figure 4 This is a top view schematic diagram of a plasma melting furnace according to this application;

[0038] Figure 5 This is a schematic diagram of the spiral feed pipe structure in a plasma melting furnace according to this application.

[0039] Explanation of the labels in the diagram:

[0040] 01. Melting furnace; 011. Furnace body; 012. Plasma anode; 013. Plasma cathode; 0131. Plasma gas channel; 014. Exhaust gas outlet pipe; 02. Spiral feed pipe; 021. Water cooling jacket; 022. Spiral blades. Detailed Implementation

[0041] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0042] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0043] The present invention will be further described below with reference to embodiments.

[0044] Example 1

[0045] This embodiment of a plasma melting furnace 01 includes a furnace body 011, a plasma anode 012 disposed within the furnace body 011, and a plasma cathode 013 disposed opposite to the plasma anode 012. During operation, the plasma anode 012 and plasma cathode 013 form a plasma coverage area, which is the area directly scanned by the plasma cathode 013. This plasma coverage area possesses an ultra-high temperature exceeding 5000°C and high-density thermal energy. The plasma coverage area, i.e., the flame coverage area formed by the plasma cathode, is generally a conical region.

[0046] The furnace body 011 is also equipped with a feeding mechanism, which is offset from the plasma cathode, and the material outlet of this feeding mechanism is aligned with the plasma coverage area. The feeding mechanism is used to transport the material into the plasma coverage area, facilitating rapid melting within the plasma, thereby improving the melting efficiency and throughput of the melting furnace 01. Simultaneously, fine dust and other small particles in the material are quickly agglomerated into droplets in the high-temperature environment, preventing them from becoming fly ash and mixing into the exhaust gas, entering the subsequent high-temperature flue gas cooling device, and causing adverse effects on the device. The material can be waste catalysts, ash, organic waste, and other solid waste or hazardous waste.

[0047] On the other hand, if the distance between the plasma cathode and anode is increased to expand the plasma coverage area in order to allow more material to fall into the plasma coverage area, there is a risk of arc interruption, which is not conducive to the continuous normal operation of the melting furnace 01, nor to improving the material processing efficiency. In this embodiment, the material is fed into the coverage area as much as possible through the feeding mechanism, which is a practical and effective way to improve melting efficiency.

[0048] After being melted at high temperatures, the materials form molten glass and molten alloy. The molten glass is then quenched in a cold quenching tank to form glass slag, which can be recycled. The molten alloy contains a large amount of metals such as copper and nickel, which can also be recycled after cooling.

[0049] Because the temperature inside furnace body 011 is high, the temperature of the molten glass is maintained at 1300-1600℃, the temperature of the alloy liquid is maintained at 1500-1600℃, and the temperature of the air inside the furnace above the molten glass is also around 1200℃. Furthermore, the temperature and energy density of the area directly scanned by the plasma cathode 013 are even higher. The inner wall of furnace body 011 is mostly made of materials with good fire resistance and heat resistance. At the same time, in order to prevent heat loss, an additional insulation layer is required.

[0050] Moreover, the toxic and harmful gases generated from the melting of materials and the small molecule gases such as carbon monoxide and hydrogen generated from the cracking of organic matter are sent into the combustion chamber for secondary combustion along with the exhaust gas through the exhaust gas outlet pipe 014.

[0051] Example 2

[0052] This embodiment is based on Embodiment 1, and its difference from Embodiment 1 is as follows:

[0053] Combination Figure 3 The plasma cathode 013, a graphite electrode, is located at the upper end of the furnace body 011. The plasma cathode 013 is vertically downward, and its central axis coincides with the central axis of the furnace body 011, i.e., it is located at the exact center of the upper part of the furnace body 011. A plasma gas channel 0131 is provided at the central axis of the plasma cathode 013 for the passage of plasma gas; in this embodiment, the plasma gas is nitrogen. The plasma anode is located at the lower end of the furnace body 011, opposite to the plasma cathode 013, and includes two graphite electrodes.

[0054] The feeding mechanism is a spiral feed tube 02, which is located at the upper end of the furnace body 011. The spiral feed tube 02 is inclined, and its material outlet is aligned with the plasma-covered zone. This allows the material passing through the spiral feed tube 02 to gain an initial velocity under the propulsion of the spiral blades 022. The initial velocity of the material is 10–30 m / s, which is within the normal range. For example, if the initial velocity is 10 m / s, the material will fall into the plasma-covered zone. The spiral feed tube 02 is made of high-temperature resistant material or has a surface covered with high-temperature resistant material. The initial velocity is the speed at which the material leaves the spiral feed tube 02. The material needs a certain initial velocity to maintain its motion within the melting furnace 01 and, under the influence of gravity, fall into the plasma-covered zone or onto the molten glass or material pile below the plasma-covered zone.

[0055] In one embodiment of this invention, the angle between the inclined spiral feed tube 02 and the plasma cathode 013 is α, which is 30° to 60°. This angle is adjustable, allowing for the adjustment of the initial velocity direction of the material to accommodate different materials entering the plasma coverage area, achieving rapid melting and improving material processing efficiency. Simultaneously, the initial velocity of the material can be controlled by adjusting the angle α. Typically, the angle α between the spiral feed tube 02 and the plasma cathode 013 is a fixed 45°.

[0056] The distance L1 between the inlet end of the spiral feed tube 02 and the central axis of the plasma cathode 013 is 0.8–1.2 m. With the length of the spiral feed tube 02 extending into the furnace body 011 remaining constant, the distance L1 between the inlet end of the spiral feed tube 02 and the central axis of the plasma cathode 013 is achieved by adjusting the angle α between the spiral feed tube 02 and the plasma cathode 013. If the distance L1 is too short, i.e., the angle α between the spiral feed tube 02 and the plasma cathode 013 is too small, the outlet end of the spiral feed tube 02 is too far from the plasma coverage area, making it difficult for the material to fall into the plasma coverage area, which is detrimental to the melting of the material. If the distance L1 is too long, i.e., the angle α between the spiral feed tube 02 and the central axis of the plasma cathode 013 is too large, the spiral feed tube 02 is prone to touching the plasma cathode 013, causing leakage.

[0057] Furthermore, the length L2 of the spiral feed pipe 02 extending into the furnace body 011 is 0.5 to 0.9 m. If the length L2 is too small, the outlet end of the spiral feed pipe 02 will be too far from the plasma coverage area, and the material will not fall into the plasma coverage area when it leaves the spiral feed pipe 02. However, if the length L2 extending into the furnace body 011 is too large, the spiral feed pipe 02 will also come into contact with the plasma cathode 013 and cause leakage, which will threaten the safety of the staff.

[0058] After adjusting and determining the angle α between the spiral feed pipe and the plasma cathode 013 and the length L2 of the spiral feed pipe 02 extending into the furnace body 011, the material passes through the spiral feed pipe 02 and obtains an initial velocity of 10-30 m / s under the push of the spiral blades 022, and can fall into the plasma coverage area.

[0059] On the other hand, whether the material falls into the plasma coverage area can be directly observed using a camera inside the furnace. Since the plasma voltage increases after the material enters the plasma coverage area and begins to melt, it can also be indirectly inferred from the changes in plasma voltage.

[0060] There are multiple spiral feed pipes 02, which are evenly arranged in a ring around the plasma cathode 013, allowing material to enter the melting furnace 01 simultaneously from multiple directions. The number of spiral feed pipes 02 is determined based on factors such as material throughput, the inner diameter of the melting furnace 01, material particle size distribution, material bulk density, and theoretical heat of fusion. One to eight spiral feed pipes 02 can be installed. Simultaneously, the location of the exhaust gas outlet pipe 014, i.e., the maintenance space above the furnace body 011, should be considered. For example, a manhole space should be provided above the furnace body 011 to facilitate maintenance during unit shutdown or in case of malfunction.

[0061] Combination Figure 4In one embodiment of this invention, the melting furnace 01 is provided with three spiral feed pipes 02, which are arranged in a ring around the plasma cathode 013 at 120° intervals. Material can enter the melting furnace 01 relatively evenly from three directions and fall into the plasma coverage area, which is beneficial for the uniform and rapid melting of the material.

[0062] Example 3

[0063] This embodiment is based on Embodiment 2, and the difference between it and Embodiment 2 is as follows:

[0064] Combination Figure 5 An inert gas is also provided inside the spiral feed pipe 02. The pressure of the inert gas inside the spiral feed pipe 02 is greater than the pressure inside the furnace, i.e., the pressure of the gas above the molten glass inside the furnace, so as to enable the material at the material outlet of the spiral feed pipe 02 to obtain an initial velocity of 10-30 m / s. Specifically, in this embodiment, the inert gas is nitrogen. That is, the pressure of nitrogen inside the spiral feed pipe 02 is greater than the pressure inside the furnace body 011, forming a pressure difference. This pressure difference makes it easier for the material to obtain an initial velocity of 10-30 m / s. Under the combined action of the driving force of the spiral blades 022 and the force brought about by the pressure difference, the material obtains an initial velocity of 10-30 m / s and can fall into the plasma coverage area. For example, if the initial velocity of the material is 20 m / s, rapid melting under high temperature and high heat can be achieved, improving the processing efficiency and processing capacity of the melting furnace 01. Moreover, the pressure difference formed by the nitrogen pressure in the spiral feed pipe 02 being greater than the pressure in the furnace body 011 is beneficial for guiding fine particles such as fly ash in the material to the plasma coverage area, where they are melted into droplets, thus avoiding the generation of a large amount of secondary ash.

[0065] On the other hand, because the nitrogen pressure inside the spiral feed pipe 02 is greater than the furnace pressure and the pressure inside the furnace body 011 remains at a slightly negative pressure, waste gas generated during the material melting process enters the spiral feed pipe 02 and may even enter the atmosphere, polluting the environment. Furthermore, nitrogen also acts as a seal, preventing other gases from entering the furnace and causing side reactions that could affect the normal melting process. Of course, it also prevents gases generated during melting from entering the spiral feed pipe 02.

[0066] Furthermore, the pressure difference Y between the pressure inside the furnace body 011 and the nitrogen pressure inside the spiral feed pipe 02 is -200 to 0 Pa (gauge pressure), that is, the pressure difference between the pressure inside the furnace body 011 and the nitrogen pressure inside the spiral feed pipe 02 is -200 to 0 Pa (gauge pressure). For example, when the pressure inside the furnace body 011 is -150 Pa (gauge pressure) and the nitrogen pressure is 10 Pa (gauge pressure), the pressure difference Y between the pressure inside the furnace body 011 and the nitrogen pressure inside the spiral feed pipe 02 is -160 Pa (gauge pressure), that is, the pressure difference is -160 Pa (gauge pressure), which allows the material to fall into the plasma coverage area. When the pressure inside furnace body 011 is -100 Pa (gauge pressure), the nitrogen pressure is 0 Pa (gauge pressure). At this time, the pressure difference Y between furnace body 011 and nitrogen pressure in spiral feed pipe 02 is -100 Pa (gauge pressure), which is sufficient to meet the requirement of material falling into the plasma coverage area. Under normal circumstances, to prevent gas leakage from the melting furnace 01, the pressure inside furnace body 011 is generally maintained at a slightly negative pressure of -80 to -20 Pa (gauge pressure), and the nitrogen pressure in spiral feed pipe 02 is maintained at 0 Pa (gauge pressure).

[0067] The angle between the spiral feed pipe 02 and the plasma cathode, and the length of the spiral feed pipe extending into the furnace are adjusted and determined. Under the combined action of the driving force of the spiral blade 022 and the force brought about by the pressure difference, the material has an initial velocity of 10-30 m / s, which can be transported to the plasma coverage area for melting.

[0068] In practice, the angle α between the spiral feed tube 02 and the plasma cathode 013, the length L2 of the spiral feed tube 02 extending into the furnace, the rotation speed of the spiral blades 022, and the nitrogen pressure can be adjusted according to the type and quality of the material to control the initial velocity of the material and further control the landing point, ensuring that the material falls into the plasma coverage area for rapid melting and improved processing efficiency and throughput. For example, for materials with a larger mass, the length L2 of the spiral feed tube 02 extending into the furnace, the rotation speed of the spiral blades 022, or the nitrogen pressure can be appropriately increased to increase the force on the material or shorten the distance between the spiral feed tube 02 and the plasma coverage area, so that the material falls smoothly into the plasma coverage area. For materials with a lighter mass, the length L2 of the spiral feed tube 02 extending into the furnace, the rotation speed of the spiral blades 022, or the nitrogen pressure can be appropriately decreased to reduce the force on the material and the distance between the spiral feed tube 02 and the plasma coverage area, preventing the material from flying out of the plasma coverage area before melting due to an excessive initial velocity.

[0069] Generally, to ensure the overall sealing of the melting furnace 01 and to make the adjustment simple and quick, the rotation speed of the spiral blade 022 and the nitrogen pressure are usually adjusted. By adjusting the rotation speed of the spiral blade 022, that is, adjusting the relevant parameters of the driving force of the spiral blade 022 or the nitrogen pressure, the landing point of different materials can be controlled.

[0070] Furthermore, the distance between the outlet end of the spiral feed pipe 02 and the end of the spiral blade 022 is L3, where L3 ≥ 0.3m. The material continues to slide forward within this distance, gaining acceleration to achieve an initial velocity of 10–30 m / s. This distance also facilitates nitrogen purging to cool the outlet end of the spiral feed pipe 02, protecting it.

[0071] Furthermore, to protect the spiral feed tube 02 and extend its service life, a water-cooling jacket 021 is installed on the outer wall of the spiral feed tube 02 to cool it down promptly, preventing the spiral feed tube 02 from overheating and affecting its normal and long-term use. If the water-cooling jacket 021 is damaged and leaks water, preventing normal cooling, the spiral feed tube 02 needs to be replaced immediately. The small amount of leaked water will remain on the surface of the molten glass and evaporate quickly, without affecting the melting of the material. The presence of damage or leakage in the water-cooling jacket 021 can be directly observed and confirmed through a camera inside the furnace body 011; alternatively, a temperature sensor can be installed on the spiral feed tube 02 to monitor its temperature and determine if the water-cooling jacket 021 is leaking, preventing cooling of the spiral feed tube 02.

[0072] As another implementation of the embodiment, the plasma melting furnace can be a melting furnace with an inner diameter greater than 3m or a power greater than 4MW, also known as a large-diameter melting furnace. For large-diameter melting furnaces, the diameter is large, but the plasma coverage area during operation is small. If the traditional vertical downward feeding or wall-feeding method is still used, the problems of slow melting speed, low melting capacity per unit cross-section, and low working efficiency of the melting furnace become more prominent. However, under the combined action of the driving force of the spiral blades 022 in the spiral feed pipe 02, the pressure difference formed by the furnace pressure and nitrogen pressure, the material gains initial velocity after passing through the spiral feed pipe 02 and falls directly into the plasma coverage area, which can melt in a timely and effective manner, avoiding the problems caused by the above-mentioned vertical feeding and wall-feeding methods, and making the material processing efficiency of the melting furnace higher.

[0073] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A plasma melting furnace, comprising a furnace body, wherein a plasma anode and a plasma cathode are disposed opposite to the plasma anode within the furnace body; Its features are: The furnace body is also equipped with a feeding mechanism, which is offset from the plasma cathode, and the material outlet of the feeding mechanism is aligned with the plasma coverage area. The feeding mechanism is used to transport materials into the plasma coverage area.

2. The plasma melting furnace according to claim 1, characterized in that: The plasma anode is located at the lower end of the furnace body, and the plasma cathode is located at the upper end of the furnace body; The feeding mechanism is a spiral feed tube, which is located at the upper end of the furnace body. The spiral feed tube is inclined, and the material outlet of the spiral feed tube is aligned with the plasma coverage area.

3. The plasma melting furnace according to claim 2, characterized in that: There are multiple spiral feed tubes, which are evenly arranged in a ring around the plasma cathode. The angle between the spiral feed tube and the plasma cathode is α, where α is 30° to 60°.

4. The plasma melting furnace according to claim 3, characterized in that: The distance L1 between the inlet end of the spiral feed tube and the plasma cathode is 0.8 to 1.2 m.

5. The plasma melting furnace according to claim 3, characterized in that: The length L2 of the spiral feed pipe extending into the furnace body is 0.5 to 0.9 m.

6. The plasma melting furnace according to claim 5, characterized in that: The distance between the outlet end of the spiral feed pipe and the end of the spiral blade is L3, where L3 ≥ 0.3m.

7. The plasma melting furnace according to claim 3, characterized in that: An inert gas is installed inside the spiral feed tube. The pressure of the inert gas inside the spiral feed tube is greater than the gas pressure inside the furnace. This is used to give the material an initial velocity at the material outlet of the spiral feed tube.

8. The plasma melting furnace according to claim 7, characterized in that: The difference between the pressure inside the melting furnace and the pressure of the inert gas is Y, where Y ranges from -200 to 0 Pa.

9. The plasma melting furnace according to claim 3, characterized in that: The initial velocity of the material is 10–30 m / s, so that the material falls into the plasma coverage area.

10. The plasma melting furnace according to claim 9, characterized in that: The outer wall of the spiral feed tube is equipped with a water-cooling jacket for cooling the spiral feed tube.

11. The method of using the plasma melting furnace according to any one of claims 1-10, characterized in that, Includes the following steps: The plasma cathode and plasma anode, which are positioned opposite each other, are opened to form a plasma coverage area; After being sealed with nitrogen, the material gains initial velocity through the inclined spiral feed pipe that extends into the furnace body and falls into the plasma coverage area. Adjust the angle α between the spiral feed tube and the plasma cathode, the length L2 of the spiral feed tube extending into the furnace, the rotation speed of the spiral blades, and the nitrogen pressure to ensure that materials of different masses fall into the plasma coverage area. The materials are melted into molten glass and molten alloy, with the molten glass in the upper layer and the molten alloy in the lower layer; both the molten glass and molten alloy are recycled; the flue gas generated from the melting of the materials is sent to the combustion chamber through the exhaust outlet pipe.

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