Vertical tank reduction system and method based on external preheating

Abstract

The application provides a vertical tank reduction system and method based on external preheating, which comprises: a material preheating device for preheating materials at a high temperature; a heat-preservation material transfer device for transferring the materials preheated at a high temperature by the material preheating device to a vertical tank reduction furnace in a heat-preservation state; and a vertical tank reduction furnace for receiving the materials transferred by the heat-preservation material transfer device, wherein the preheated materials can enter a reduction reaction by vacuumizing and continuously heating in the vertical tank furnace. The application realizes efficient preheating of the materials outside the reduction tank by adding the material preheating device to the traditional reduction system, and the preheated materials enter the reduction tank system to perform the reduction reaction, thereby shortening the time of invalid heating of the materials in the vertical tank reduction furnace, shortening the reduction cycle of the vertical tank reduction furnace from 16-20 hours to 6-8 hours, and greatly improving the reduction work efficiency of the vertical tank reduction furnace, so that the production capacity is doubled without increasing the personnel, fuel consumption, power consumption and tank consumption.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a vertical tank reduction system and method based on external preheating. Background Technology

[0002] The main method used in my country for magnesium smelting is the "silicothermic process," also known as the "Pidgeon process." This involves placing a mixture of calcined dolomite, ferrosilicon, and fluorite into powder and pressing it into pellets inside a sealed, heat-resistant metal container. The magnesium is then extracted through reduction and condensation under high temperature (1200℃~1300℃) and vacuum (≤13Pa) conditions.

[0003] Earlier reduction tanks were placed horizontally inside the reduction furnace. This was because the horizontal reduction process had disadvantages such as poor working conditions, environmental pollution, large footprint, difficulty in loading, and high labor requirements. The reduction cycle of the horizontal tank was generally 10 to 12 hours. Currently, the reduction furnace has been upgraded to a vertical reduction furnace, which has eliminated the disadvantages of the horizontal reduction furnace, such as difficulty in loading and unloading, high labor requirements, poor environment, and high energy consumption.

[0004] The specific process of a vertical reduction furnace involves directly loading pressed pellets into a vertical reduction vessel. After loading, the vessel is covered and a vacuum is created. The pellets inside the reduction vessel are heated under vacuum conditions, and once they reach the reduction temperature, they produce metallic magnesium vapor, which condenses into crude magnesium in the upper condenser. However, due to factors such as the exhaust method and the heating area per unit volume of material, the reduction cycle of a vertical reduction furnace is generally long, ranging from 16 to 20 hours. In reality, the actual reduction reaction begins at 1180℃, and 6 to 8 hours is sufficient for the reduction reaction. Before reaching 1180℃, the main task is to raise the temperature of the material. There are three forms of heat transfer: conduction, radiation, and convection. However, under the vacuum reduction conditions of a vertical reduction furnace, convection heat transfer does not exist, leaving only radiation and conduction heat transfer. Conduction heat transfer is positively correlated with the contact area between the material and the vertical reduction furnace, while radiation heat transfer is positively correlated with the radiation area that the material can receive. When the material balls are stationary inside the vertical reduction furnace, the effects of conduction and radiation heat transfer are limited, resulting in a very slow heating process before the material reacts, which greatly affects the operating efficiency of the vertical reduction furnace.

[0005] Meanwhile, in the traditional vertical tank reduction process, during the preheating of the material before it reaches the reduction temperature, the vacuum unit is doing useless work, and the central tube will also generate additional consumption during the preheating process.

[0006] Finally, in the traditional vertical reboiler reduction process, if the temperature of the low-temperature material layer inside the reboiler is too low, the high-temperature reducing steam will condense in the low-temperature material layer and cannot fall smoothly to discharge slag. For a vertical reboiler reduction furnace, the inability to discharge slag smoothly means that new material cannot be loaded, leading to operational stagnation. To avoid this problem, the existing solution is to slow down the heating rate and extend the heating time during the initial preheating of the vertical reboiler reduction furnace, waiting until the temperature of the inner material reaches above the temperature at which the reducing steam cannot condense before heating to the designated high temperature. Due to the limitations of the material's thermal conductivity, the initial heating often takes a long time (6-8 hours or even longer), and even then, the accuracy of the delay cannot be guaranteed, and some reduction reboilers may experience slag agglomeration.

[0007] The problems mentioned above in existing technologies will significantly increase tank consumption, energy consumption, electricity consumption, and central tube consumption. Summary of the Invention

[0008] This invention provides a vertical tank reduction system and method based on external preheating, which solves the problems of long reduction time, high reduction energy consumption and low production efficiency in the prior art.

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

[0010] A vertical tank reduction system based on external preheating, the reduction system comprising:

[0011] Material preheating device, used for the initial high-temperature preheating of materials;

[0012] A heat-insulated material transfer device is used to transfer the material preheated at high temperature in the front stage of the material preheating device to the vertical tank reduction furnace under heat-insulated conditions.

[0013] The vertical tank reduction furnace is used to receive the material transferred by the heat-insulating material transfer device. The high-temperature preheated material can enter the reduction reaction after being vacuumed and heated further in the vertical tank furnace.

[0014] Furthermore, the material preheating device is a rotary preheating furnace, including a support frame system and a rotating drum arranged laterally on the support frame system. The rotating drum has a circular cross-sectional shape. One end of the rotating drum is connected to the feed port and the other end is connected to the discharge port. Both the feed port and the discharge port are equipped with double-layer interlocking sealing doors. The rotating drum is connected to a drive mechanism, which drives the rotary furnace body to rotate along the axis. A heating device is installed outside the rotating drum, and the rotating drum is connected to a controllable atmosphere circuit.

[0015] Furthermore, the material preheating device is a vertical preheating furnace, including a support frame system and a vertical furnace body installed on the support frame system. The cross-sectional shape of the vertical furnace body is circular or square. The upper end of the vertical furnace body is a feed inlet with a sealed cover, and the lower side wall of the vertical furnace body is provided with a discharge outlet with a sealed cover. A nitrogen heating system is connected to the lower end of the vertical furnace body. The nitrogen heating system includes a nitrogen heating pipeline, a nitrogen circulation pipeline, a nitrogen high-pressure circulation fan, and a heating device. The hot gas outlet of the nitrogen heating pipeline is connected to the lower part of the vertical furnace body, the cooling gas inlet of the nitrogen heating pipeline is connected to the lower end of the nitrogen circulation pipeline, the upper end of the nitrogen circulation pipeline is connected to the upper part of the vertical furnace body, and the nitrogen high-pressure circulation fan is installed on the nitrogen circulation pipeline.

[0016] Furthermore, a grate is obliquely arranged at the bottom of the vertical furnace body, and materials are filled into the vertical furnace body above the grate.

[0017] Furthermore, both the rotating drum and the vertical furnace body are equipped with thermocouples and pressure gauges.

[0018] Furthermore, the heating device is an electric heating device, a fuel heating device, or a reaction waste heat heating device.

[0019] Furthermore, the heat-insulating material transfer device includes a transfer vehicle and a box mounted on the transfer vehicle. The upper end of the box is provided with an inlet with a top cover, and the bottom of the box is a sloping surface. The lowest point of the sloping surface is provided with an outlet with a bottom cover. The box, the top cover, and the bottom cover are made of high-density aluminum silicate fireproof plate.

[0020] Furthermore, the vertical reduction furnace includes a reduction tank body, with a slag outlet at the lower end and an opening at the upper end. A condensation system is sealed and connected to the upper end of the tank opening. A central tube is fixedly installed inside the reduction tank body, and an exhaust vent plate is longitudinally installed inside the reduction tank body. Multiple exhaust vents are opened on the exhaust vent plate, and the exhaust vents have an inverted triangular structure. Material is filled between the central tube and the exhaust vent plate, and the exhaust vent plate and the inner wall of the reduction tank body form a channel for the reaction gas to rise.

[0021] Furthermore, the central tube includes a metal core tube, with multiple sets of anchor hooks arranged in a ring around the outer side of the metal core tube. The outer wall of the metal core tube is covered with a ceramic castable layer, and the anchor hooks are embedded in the ceramic castable layer.

[0022] The vertical tank reduction method based on external preheating uses an external material preheating device to preheat the material to be reduced at a high temperature. The temperature of the preheating is lower than the minimum temperature of the reduction reaction. Then, the preheated material is added to the vertical tank reduction furnace for reduction reaction.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention adds a material preheating device to the traditional reduction system, achieving efficient preheating of the material outside the reduction tank. The preheated material enters the reduction tank system for reduction reaction, greatly shortening the reduction reaction time and the time when the material is ineffectively heated in the vertical tank reduction furnace. This reduces the reduction cycle of the vertical tank reduction furnace from 16-20 hours to 6-8 hours, enabling the vertical tank reduction furnace to truly achieve a significant increase in reduction operation efficiency. It doubles the production capacity without increasing personnel, fuel consumption, electricity consumption, or tank consumption.

[0025] 2. The material preheating device of the present invention performs efficient preheating of the material outside the reduction tank, which increases the strength of the material after preheating and dissolves the powder on the surface, avoiding the breakage of the material loaded into the vertical tank reduction furnace, reducing the phenomenon of slag formation on the inner wall of the vertical tank reduction furnace during the reaction process, and avoiding the problem of reduced loading and reduced output due to incomplete slag discharge.

[0026] 3. In this invention, an exhaust vent plate is installed inside the vertical reduction furnace for exhaust. The gas rising channel is located between the inner wall of the vertical reduction furnace and the exhaust vent plate. The temperature of the outer layer material (adjacent to the inner wall of the vertical reduction furnace) first reaches the reduction temperature and is reduced to metal vapor, which is then directly discharged through the exhaust vent plate. The metal vapor reduced at high temperature does not pass through the inner low-temperature material layer (adjacent to the outer wall of the central tube), thus avoiding the phenomenon of slag condensation and caking caused by the high-temperature gas entering the low-temperature material layer.

[0027] 4. In one embodiment of the present invention, the venting plate is provided with a multi-layered inverted triangular structure of venting holes in a circumferential direction. The inverted triangular structure of the venting holes prevents the gas rising channel from being blocked by broken material during loading, thus affecting the reaction efficiency.

[0028] Of course, implementing the various technical solutions of this invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 This is a schematic diagram of the rotary preheating furnace in Embodiment 1 of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the heat-insulating material transfer device according to Embodiment 1 of the present invention;

[0033] Figure 4 This is a schematic diagram of the vertical reduction furnace in Embodiment 1 of the present invention;

[0034] Figure 5 yes Figure 4 AA side sectional view;

[0035] Figure 6 This is a schematic diagram of the exhaust plate of Embodiment 1 of the present invention;

[0036] Figure 7 yes Figure 6 Top view;

[0037] Figure 8 This is a schematic diagram of gas flow through the exhaust orifice plate in Embodiment 1 of the present invention;

[0038] Figure 9 This is a schematic diagram of the structure of the central tube in Embodiment 1 of the present invention;

[0039] Figure 10 This is a schematic diagram of the vertical preheating furnace in Embodiment 2 of the present invention;

[0040] In the picture,

[0041] 1-Material preheating device;

[0042] 101-Support frame system, 102-Rotating drum, 103-Feed inlet, 104-Discharge outlet, 105-Heating device, 106-Atmosphere circuit, 107-Vertical furnace body, 108-Nitrogen heating pipeline, 109-Nitrogen circulation pipeline, 110-Nitrogen high-pressure circulating fan, 111-Burner, 112-Combustion chamber, 113-Thermocouple, 114-Grate plate, 115-Pressure gauge;

[0043] 2-Insulated material transfer device;

[0044] 201 - Box body, 202 - Top cover, 203 - Sloping surface, 204 - Bottom cover;

[0045] 3-Vertical reduction furnace;

[0046] 301-Reduction tank body, 302-Condensation system, 303-Central pipe, 304-Exhaust plate, 305-Exhaust hole, 3031-Metal core tube, 3032-Anchor hook, 3033-Ceramic castable layer;

[0047] 4. Materials. Detailed Implementation

[0048] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0049] In the description of this patent, it should be understood that the terms “center,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this patent 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. Therefore, they should not be construed as limitations on this patent.

[0050] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] Through various experiments and analysis of the results, the inventors believe that the factors leading to the long reduction cycle of the vertical flask reduction furnace include: the heating area per unit volume of material, the thickness of the material layer, the exhaust method, and the heat transfer pattern of the material. Due to the influence and constraints of various factors, the time to reach the reduction start temperature is very long, which seriously affects the reduction efficiency. Therefore, this invention mainly addresses the shortcomings of the vertical flask reduction furnace, such as the long reduction cycle and poor slag discharge, by making targeted process improvement designs.

[0052] Since the reduction reaction of the material (calcined dolomite + ferrosilicon + fluorite mixed powder pressed into pellets) needs to be carried out under high temperature (1200℃~1300℃) and vacuum (≤13Pa) conditions, the basic idea of ​​this invention is to conduct the non-reduction reaction time of the material, i.e., the preheating process of the material, in a material preheating device outside the vertical tank reduction furnace. The vertical tank reduction furnace is only used to achieve the reduction operation under vacuum conditions. The material preheating device heats the material blocks and ensures uniform heating of the material, which can shorten the reduction cycle of the vertical tank reduction furnace from 16-20 hours to 6-8 hours, eliminate the ineffective operation time of the vertical tank reduction furnace, and maximize the vacuum reduction characteristics of the vertical tank reduction furnace.

[0053] Example 1:

[0054] See Figure 1 This embodiment discloses a vertical tank reduction system based on external preheating, including a material preheating device 1, an insulated material transfer device 2, and a vertical tank reduction furnace 3. The components are described in detail below.

[0055] Material preheating device 1 is used for the initial high-temperature preheating of material 4; see [link / reference] Figure 2 In this embodiment, the material preheating device 1 is a rotary preheating furnace, which utilizes the fluidization heating principle of the rotary preheating furnace to achieve high-temperature preheating of the material 4.

[0056] The rotary preheating furnace includes a support frame system 101, a rotating drum 102, a feed inlet 103, a discharge outlet 104, a heating device 105, and an atmosphere circuit 106. The rotating drum 102 is horizontally arranged on the support frame system 101. The rotating drum 102 has a circular and hollow cross-section. One end of the rotating drum 102 is connected to the feed inlet 103, and the other end is connected to the discharge outlet 104. Both the feed inlet 103 and the discharge outlet 104 are equipped with double-layer interlocking sealing doors. The double-layer interlocking sealing doors are used to reduce the air introduced into the rotating drum 102 when the feed inlet 103 and the discharge outlet 104 are opened and closed, so as to prevent the ferrosilicon in the material 4 from being oxidized during the heating process.

[0057] The rotating drum 102 is connected to a drive mechanism, which drives the rotating drum 102 to rotate around its central axis, thereby achieving heating of material 4 under fluid conditions. The specific principle of heating under fluid conditions is as follows: low-temperature material and high-temperature material flow together when the rotating drum rotates, and the contact between them during the flow increases the temperature difference for heat transfer; secondly, during the flow mixing process, low-temperature material has the opportunity to contact the high-temperature tank wall, increasing conduction heat transfer; at the same time, high-temperature material and low-temperature material also transfer heat to each other during the fluidization process, and fluidization keeps the materials in dynamic contact, thus resulting in an overall improvement in heat transfer.

[0058] A heating device 105 is fitted around the outside of the rotating drum 102. In this embodiment, the heating device 105 is an induction heating device, which can heat the rotating drum 102 intermittently or continuously. In other embodiments, the heating device can also be a gas fuel heating device or a heating device based on the excess high-temperature flue gas in the reduction furnace.

[0059] During the high-temperature preheating process before magnesium reduction, it is necessary to prevent the ferrosilicon reducing agent in material 4 from being oxidized. Once ferrosilicon is oxidized, its utilization rate will be reduced, silicon consumption will increase, and costs will increase. Therefore, an inert gas needs to be introduced as an anti-oxidation protection for ferrosilicon. In this embodiment, the rotating drum 102 is connected to a controllable atmosphere circuit 106 to fill the rotating drum 102 with inert gas. In this embodiment, argon is selected as the inert gas. Argon is used to replace the air in the rotary preheating furnace, and then the preheating is carried out under a slightly positive pressure of argon in the furnace, thereby ensuring that material 4 is not oxidized or the oxidation is reduced during the preheating process. In other embodiments, nitrogen can also be selected as the inert gas.

[0060] A thermocouple is installed in the middle of the material balls in the rotating drum 102 to measure the temperature of the material balls heated by the rotary preheating furnace. When the temperature detected by the thermocouple reaches the temperature required for the material balls to be preheated at a high temperature (900-1100℃), the material is unloaded into the heat-insulating material transfer device 2. A pressure gauge 115 is also installed inside the rotating drum 102 to monitor the gas pressure inside the vertical preheating furnace in real time.

[0061] The heat-insulated material transfer device 2 is used to transfer the material 4, which has been preheated at high temperature in the front stage of the material preheating device, to the vertical tank reduction furnace under heat-insulated conditions.

[0062] See Figure 3 The heat-insulating material transfer device 2 includes a transfer vehicle and a box 201 mounted on the transfer vehicle. The upper end of the box is provided with an inlet with a top cover 202. The bottom of the box 201 is a sloping surface 203. In this embodiment, two sloping surfaces 203 are provided, and the two sloping surfaces 203 are joined together to form a ∧ shape. The sloping surfaces 203 facilitate the flow of material 4. The angle of the sloping surfaces 203 is the angle of repose of material 4. The lowest point of the sloping surfaces 203 is provided with an outlet with a bottom cover 204. When discharging, the bottom cover 204 is opened, and material 4 will automatically flow into the vertical tank reduction furnace 3. The box 201, the top cover 202, and the bottom cover 203 are made of high-density aluminum silicate fireproof plate material, which is heat-resistant to 1200℃. A heat-insulating layer of ceramic fiber and porous ceramic is provided outside the high-density aluminum silicate fireproof plate material to reduce the heat loss of the box 201 and achieve the effect of temperature drop of less than 100℃ after 8 hours of heat preservation. In this embodiment, the thermal insulation material transfer device is a single-box structure. In other embodiments, the thermal insulation material transfer device can be designed as a four-box integrated type, a six-box integrated type, or an eight-box integrated type, as needed.

[0063] The vertical reduction furnace 3 is used to receive the material 4 transferred by the heat-insulating material transfer device 2. The material 4, which is preheated at high temperature, can directly undergo reduction reaction in the vertical reduction furnace 3.

[0064] See Figure 4 and Figure 5The vertical reduction furnace 3 includes a reduction tank body 301. A slag outlet is located at the lower end of the reduction tank body 301, and an opening is located at the upper end of the tank body 301. A condensation system 302 is sealed and connected to the upper end of the tank opening. A central tube 303 is fixedly installed inside the reduction tank body 301. An exhaust vent plate 304 is longitudinally installed inside the reduction tank body 301, extending 20-30 mm from the bottom. In this embodiment, two exhaust vent plates 304 are provided, symmetrically welded to the inside of the reduction tank body 301 along the diameter of its cross-sectional circle. Each exhaust vent plate 304 forms a space with the inner wall of the reduction tank body 301. There are two reaction gas rising channels. Material 4 is filled between the central tube 303 and the exhaust plate 304. After the material 4 is heated to the reduction temperature, the metal vapor generated by the reaction enters the condensation system 302 for condensation through the gas rising channels. In other embodiments, the exhaust plate can be set as one or more pieces. For example, when three exhaust plates are set, the three exhaust plates are connected in sequence to form a structure with a triangular cross-section. When four exhaust plates are set, the four exhaust plates are connected in sequence to form a structure with a quadrilateral cross-section, thereby forming three or four reaction gas rising channels.

[0065] See Figures 6-8 The vent plate 304 is a long plate structure with multiple layers of vent holes 305. Each vent hole 305 has an inverted triangular structure. The inverted triangular structure of the vent hole 305 can prevent broken material from entering the gas rising channel during loading, causing blockage of the gas rising channel and affecting the reaction efficiency.

[0066] See Figure 9 In this embodiment, the central tube 303 is not used for venting, but rather for adjusting the thickness of the material layer 4. The central tube 303 is a composite structure of metal tube and ceramic. The diameter of the central tube 303 is determined based on the optimal material layer thickness for cost-effectiveness. The central tube 303 includes a centrally located metal core tube 3031, with multiple sets of anchor hooks 3032 arranged in a ring around the outer edge of the metal core tube 3031. The outer wall of the metal core tube 3031 is covered with a ceramic castable layer 3033, and the anchor hooks 3032 are embedded within the ceramic castable layer 3033. The composite structure of the metal core tube 3031 and the ceramic castable layer 3033 is used to reduce the oxidation of the metal core tube 3031, thereby improving the lifespan of the central tube 303. It is expected that the lifespan of the central tube 303 can be increased by three to five times.

[0067] The working process of this embodiment is as follows:

[0068] Step S1: Load the pressed material into the rotary preheating furnace. After loading, seal the double-layer interlocked door. Inert argon gas is first introduced into the rotary preheating furnace through the atmosphere circuit to replace the remaining air in the rotating drum. After replacement, depending on the sealing degree of the rotary preheating furnace, the argon gas can be turned off or a small amount of argon gas can be introduced to maintain a slight positive pressure. The purpose is to ensure that there is no oxygen or oxidizing atmosphere in the rotating drum, so as to avoid the oxidation of ferrosilicon in the material at high temperature. The rotating drum achieves heating of the material under fluid conditions while rotating.

[0069] Step S2: When the material temperature in the rotary preheating furnace reaches 900℃~1100℃, the material preheated at the previous high temperature is introduced into a heat-insulating material transfer device with heat resistance and heat preservation effect. The heat-insulating material transfer device transfers the material to the vertical tank reduction furnace for reduction reaction.

[0070] Step S3: Vacuum is drawn inside the vertical reduction furnace. The material preheated at high temperature in the front stage is heated from 900℃~1100℃ to above 1180℃ under vacuum conditions, and the reduction reaction begins. Since the heating device of the vertical reduction furnace is outside, the temperature of the outer layer of material adjacent to the inner wall of the vertical reduction furnace reaches the reduction temperature first. After the metal vapor is reduced, it is directly discharged from the exhaust plate on its outer side. The metal vapor enters the condensation system upward for condensation. The temperature of the inner layer of material adjacent to the outer wall of the central tube then reaches the reduction temperature. The metal vapor passes through the outer layer of material and the exhaust plate in sequence, and then enters the condensation system upward for condensation. Since the outer layer of material is always at a high temperature, the metal vapor generated by the inner layer of material will not condense in the tank, resulting in tank condensation, which affects the slag discharge and aeration effect.

[0071] Example 2:

[0072] Unlike Example 1, the material preheating device 1 in this example is a vertical preheating furnace, see [link to example]. Figure 10The furnace includes a support frame system 101 and a vertical furnace body 107 mounted on the support frame system 101. The vertical furnace body 107 has a circular cross-sectional shape, and its lining is made of high-strength, high-alumina fiberboard, which has good heat insulation properties. The upper end of the vertical furnace body 107 has a feed inlet 103 with a sealed cover, and the lower side wall of the vertical furnace body 107 has a discharge outlet 104 with a sealed cover. A nitrogen heating system is connected to the lower end of the vertical furnace body 107. In this embodiment, the nitrogen heating system... A shell-and-tube heater with a tubular structure is selected, including a nitrogen heating pipe 108, a nitrogen circulation pipe 109, a nitrogen high-pressure circulating fan 110, and a heating device 105. The hot gas outlet of the nitrogen heating pipe 108 is connected to the lower part of the vertical furnace body 107, the cooling gas inlet of the nitrogen heating pipe 108 is connected to the lower end of the nitrogen circulation pipe 109, and the upper end of the nitrogen circulation pipe 109 is connected to the upper part of the vertical furnace body 107. The nitrogen high-pressure circulating fan 110 is located at the nitrogen... In this embodiment, the heating device 105 on the gas circulation pipeline 109 is a gas fuel heating device, including a burner 111. The burner 111 generates high-temperature flue gas in the combustion chamber 112. The high-temperature flue gas flows outside the nitrogen heating pipeline 108, and the nitrogen flows inside the nitrogen heating pipeline 108. Through heat exchange, the nitrogen is heated to about 1000-1100°C. The heated nitrogen is drawn upward from the bottom of the vertical furnace body 107 by the high-pressure nitrogen circulation fan 110. During the flow, the material 4 is heated, and the nitrogen releases heat and is gradually cooled down. The cooled nitrogen enters the nitrogen heating pipeline 108 again under the action of the high-pressure nitrogen circulation fan 110 and is heated up again. This cycle completes the preheating of the material 4 at a high temperature. In this embodiment, the nitrogen heating pipeline 108 is a high-temperature resistant metal pipe, and the material can be 310S. In other embodiments, the heating device can also be based on electric heating or on the heating of excess high-temperature flue gas in the reduction furnace.

[0073] To further enhance the heat exchange efficiency of nitrogen, a grate 114 is obliquely installed at the bottom of the vertical furnace body 107. Material 4 is filled into the vertical furnace body 107 above the grate 114, and a high-temperature nitrogen input space is formed below the grate 114.

[0074] In this embodiment, thermocouple 113 is installed in the material 4 to monitor the temperature of the material 4. The temperature measuring point is located at the height of the single unloading volume. When the temperature monitored by thermocouple 113 reaches 900-1100℃, the sealing cover of the discharge port 104 is opened to start unloading, and the high-temperature material 4 enters the heat preservation material transfer device 2. Pressure gauge 115 is also installed in the vertical furnace body 107 to monitor the gas pressure inside the vertical preheating furnace in real time.

[0075] It should be emphasized that the rotary preheating furnace and the vertical preheating furnace are only two specific embodiments of the external preheating device of the present invention. Production modes that combine external preheating or preheating with post-reduction by those skilled in the art to which this invention pertains are all within the scope of protection of this patent.

[0076] The embodiments of this invention are mainly illustrated using the reduction of metallic magnesium as an example, and do not mean that they are only applicable to the reduction process of metallic magnesium. All fields that can utilize vertical vacuum reduction furnaces, such as the thermal reduction of metallic zinc, fall within the protection scope of this patent.

[0077] The above specific examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the ideas of this invention.

Claims

1. A vertical tank reduction system based on external preheating, characterized in that, The restoration system includes: Material preheating device, used for the initial high-temperature preheating of materials; A heat-insulated material transfer device is used to transfer the material preheated at high temperature in the front stage of the material preheating device to the vertical tank reduction furnace under heat-insulated conditions. The vertical tank reduction furnace is used to receive the material transferred by the heat-insulating material transfer device. The high-temperature preheated material can enter the reduction reaction after being vacuumed and heated further in the vertical tank furnace. The material preheating device is a vertical preheating furnace, including a support frame system and a vertical furnace body installed on the support frame system. The cross-sectional shape of the vertical furnace body is circular or square. The upper end of the vertical furnace body is a feed inlet with a sealed cover, and the lower side wall of the vertical furnace body is provided with a discharge outlet with a sealed cover. A nitrogen heating system is connected to the lower end of the vertical furnace body. The nitrogen heating system includes a nitrogen heating pipeline, a nitrogen circulation pipeline, a nitrogen high-pressure circulation fan, and a heating device. The hot gas outlet of the nitrogen heating pipeline is connected to the lower part of the vertical furnace body, the cooling gas inlet of the nitrogen heating pipeline is connected to the lower end of the nitrogen circulation pipeline, the upper end of the nitrogen circulation pipeline is connected to the upper part of the vertical furnace body, and the nitrogen high-pressure circulation fan is installed on the nitrogen circulation pipeline. The heat-insulating material transfer device includes a transfer vehicle and a box mounted on the transfer vehicle. The upper end of the box is provided with an inlet with a top cover, and the bottom of the box is a sloping surface. The lowest point of the sloping surface is provided with an outlet with a bottom cover. The box, top cover, and bottom cover are made of high-density aluminum silicate fireproof plate. The vertical reduction furnace includes a reduction tank body, with a slag outlet at the lower end and an opening at the upper end. A condensation system is sealed and connected to the upper end of the tank opening. A central tube is fixedly installed inside the reduction tank body, and an exhaust plate is longitudinally installed inside the reduction tank body. Multiple exhaust holes are opened on the exhaust plate, and the exhaust holes have an inverted triangular structure. Material is filled between the central tube and the exhaust plate, and the exhaust plate and the inner wall of the reduction tank body form a channel for the reaction gas to rise. A grate is obliquely arranged at the bottom of the vertical furnace body, and materials are filled into the vertical furnace body above the grate. The heating device is an electric heating device, a fuel heating device, or a reaction waste heat heating device; The central tube includes a metal core tube, with multiple sets of anchor hooks arranged in a ring around the outer side of the metal core tube. The outer wall of the metal core tube is covered with a ceramic castable layer, and the anchor hooks are embedded in the ceramic castable layer.

2. A vertical tank reduction method based on external preheating, characterized in that, Based on the reduction system described in claim 1, the reducing material is preheated at a high temperature by an external material preheating device. The temperature of the preheating is lower than the minimum temperature of the reduction reaction. Then, the preheated material is added to the vertical tank reduction furnace for the reduction reaction.

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