A magnesium smelting pellet waste heat recovery system and waste heat recovery method

Abstract

The present application relates to a kind of magnesium smelting pellet waste heat recovery system and waste heat recovery method, the technical field for waste heat recovery, it needs to be explained that, in the present application, magnesium smelting pellet waste heat recovery system is composed of spray heat exchange box, plate heat exchanger and heat preservation reservoir;Wherein in spray heat exchange box part, in box body, inlet and outlet are provided, in the box body inside, setting material area is provided, the inlet and outlet are located at the two sides of setting material area, liquid inlet nozzle is installed in the box body inside, outlet is connected and installed in the gas outlet of box top, the box body inside is provided with impurity blocking system towards outlet pipe mouth, circulating material turning device is provided on setting material area, the present application has the effect of improving the waste heat recovery efficiency of high-position heat energy of magnesium smelting pellet.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste heat recovery, in particular to a magnesium smelting pellet waste heat recovery system and a waste heat recovery method. BACKGROUND

[0002] In the silicon thermal method of magnesium smelting process, the calcined dolomite and ferrosilicon and fluorite are made into pellets according to the ratio, and are sent to the reduction tank, and are heated at 1180-1200℃ high temperature and 1Pa-13Pa vacuum condition for 10h to carry out reduction to prepare crude magnesium. However, in the preparation process, a large amount of heat energy is generated, which is often recycled and reused in order to save energy.

[0003] In the field of recovery of sensible heat of silicon thermal method of magnesium smelting, it is mainly realized by means of blast ring cooling machine (i.e. ring cooling machine) or exhaust belt cooling machine (i.e. belt cooling machine), but through this way, the operation is often based on the cooling of ore pellets, and the cooling system itself has a high air leakage rate, which reduces the recovery efficiency of the waste heat of the pellets. Based on this, in the existing field of waste heat recovery, such as Chinese patent CN104121786B, a waste heat recovery furnace is disclosed, specifically, a cooling cylinder is provided with a feeding port on the upper surface of the cooling cylinder, a sealing cover is configured on the feeding port to seal the feeding port, an air outlet is formed on the upper end side wall of the cooling cylinder, and the air outlet is connected with a induced draft fan, so as to realize the guiding of hot air to the cooling air pipe for recycling treatment.

[0004] Although the above-mentioned prior art can realize the recovery of waste heat of sintered ore, a large amount of dust and slag will be generated in the process of cooling the ore after high temperature preparation by spraying water, and the slag will be dispersed upward with high temperature steam, which will affect the subsequent process; in addition, a large amount of ore pellets will be put into the heat exchange box during the cooling process, and the molten ore of the upper ore after being cooled by water is easy to be hardened, which affects the efficiency of the lower ore being cooled by water, and reduces the actual heat exchange effect; finally, the existing technology adopts air flow heat exchange to recover waste heat, and the recovery effect is poor, a large amount of waste heat is easy to be wasted; therefore, there is still room for improvement in the existing field of waste heat recovery. SUMMARY

[0005] In order to improve the waste heat recovery efficiency of high-level heat energy of magnesium smelting pellets, the present application provides a magnesium smelting pellet waste heat recovery system and a waste heat recovery method.

[0006] In the first aspect, the magnesium smelting pellet waste heat recovery system provided by the present application adopts the following technical scheme:

[0007] A waste heat recovery system for magnesium smelting pellets includes a housing with an inlet and an outlet. A material storage area is located inside the housing, with the inlet and outlet situated on opposite sides of the storage area. A liquid inlet nozzle is installed inside the housing, and an outlet pipe is connected to an outlet at the top of the housing. An impurity blocking system is installed inside the housing facing the outlet pipe. A circulating material turning device is installed in the storage area.

[0008] The impurity blocking system includes a gas guide hood threaded onto the end of the gas outlet pipe. The gas guide hood is sealed at the gas outlet. An upwardly inclined air guide plate is provided inside the gas guide hood. An air guide port for steam to pass through is provided at the upper part of the air guide plate. An installation block is detachably slidably installed on the side of the air guide hood. An installation groove corresponding to the installation block is provided on the air guide hood. A positioning block is integrally provided on the side of the installation block facing the air guide port. An impurity filter plate is installed on the positioning block. A positioning groove that engages with the positioning block is integrally provided on the air guide plate.

[0009] Preferably, an active impurity remover is also provided on the upper side of the air guide plate. The active impurity remover includes an extension rod, impurity removal blades, a baffle plate, and a collection groove. The extension rods are symmetrically installed on the upper side of the air guide plate. The baffle blades are rotatably installed on the extension rods and can cover the air guide openings. The baffle plate is installed on the side of the extension rod facing the mounting groove, and the baffle plate has a through groove for the impurity removal blades to pass through. The mounting block is recessed inward to form a collection groove. A material collection area is formed between the baffle plate and the inner sidewall of the air guide hood, and the collection groove is located in the material collection area.

[0010] The impurity removal blades are equipped with impurity removal nets.

[0011] Preferably, the impurity removal blade is equipped with a scraper, which includes a mounting sleeve, a drive spring, and a scraper plate. The mounting sleeve is sleeved on the extended end of the impurity removal blade, and the drive spring is located between the mounting sleeve and the impurity removal blade to drive the mounting sleeve to move away from the impurity removal blade. The scraper plate is located on both sides of the mounting sleeve and slides against the surface of the impurity removal mesh.

[0012] The end of the mounting sleeve furthest from the impurity removal blade is provided with a first guide surface.

[0013] Preferably, the side wall of the air guide hood is provided with an arc-shaped guide plate that cooperates with the mounting sleeve. The opening of the arc-shaped guide plate is oriented towards the scraper, and a second guide surface that cooperates with the first guide surface is provided on the upper side of the arc-shaped guide plate.

[0014] The arc-shaped guide plate has several positioning grooves sequentially opened on the side wall facing the scraper. A positioning spring is installed in the positioning groove, and the extended end of the positioning spring is fixedly connected to an abutment block that elastically abuts against the mounting sleeve.

[0015] Preferably, the circulating material turning device includes a feeding belt, a fixed frame, a first transmission rod, a second transmission rod, and a turning plate. The feeding belt is rotatably installed in the material placement area, the fixed frame is installed inside the box, the first transmission rod is rotatably installed on the side wall of the mounting frame and meshes with the feeding belt, the second transmission rod is rotatably installed on the upper side of the fixed frame and meshes with the first transmission rod, and the turning plate is sequentially installed on the second transmission rod to realize the turning operation of the material on the feeding belt.

[0016] Preferably, an abutment block is slidably mounted on the fixed frame, the upper side of the abutment block has an arc-shaped surface, and a squeezing cylinder is also provided on the fixed frame. A sealing block that slides and seals inside the squeezing cylinder is connected below the abutment block. The extended end of the squeezing cylinder faces the scraper plate on the upper surface of the feeding belt, and a lifting spring that drives the abutment block to move upward is installed on the upper side of the squeezing cylinder.

[0017] Preferably, a lifting rod is provided on the upper side of the shovel plate.

[0018] Preferably, the shovel plate is further provided with a cutting block, and a first extrusion plate and a second extrusion plate are rotatably installed between the cutting block and the lifting rod. The first extrusion plate and the second extrusion plate are rotatably connected, and the first extrusion plate is rotatably connected to the cutting block, and the second extrusion plate is rotatably connected to the lifting rod. A telescopic spring is provided between the first extrusion plate and the second extrusion plate, and the first extrusion plate and the second extrusion plate are elastic.

[0019] On the other hand, this application also discloses a method for recovering waste heat from magnesium smelting pellets, as follows:

[0020] The waste heat recovery system for magnesium smelting pellets also includes a plate heat exchanger and an insulated water storage tank. After the high-temperature pellets and room-temperature water are sprayed and heat exchanged in the spray heat exchange box to generate high-temperature steam, the steam is introduced into the plate heat exchanger for heat exchange through the steam outlet pipe. This achieves the conversion of room-temperature water into constant-temperature high-temperature water through steam. The heated constant-temperature high-temperature water is then stored in the insulated water storage tank for preservation and subsequent use.

[0021] Based on the above working process and the heat transfer formula in heat transfer, the calculation method for waste heat recovery in magnesium smelting pellets includes the following steps:

[0022] Step 1: Turn on the steam pump in the high-temperature steam pipeline, measure the pressure P1 in the spray chamber, and measure the initial temperature t0 of the pellets, the volume V of the pellet tank, and the mass m of the pellets filling the pellet tank. b And height δ and surface area A, where P1 is in pa, t0 is in ℃, and V is in m. 3 ,m b The units are kg, δ is in m, and A is in m.2 ;

[0023] Step 2: Measure the specific heat capacity c of the pellet. b The unit is J / (kg·k). Using the formula Q=cmΔt, the heat carried by a batch of high-temperature pellets in the spray chamber is calculated as c. b m b Δt, Δt = t0 - t min Q max The unit is kJ, t0 is the initial temperature of the pellet in °C, and t min The final temperature of the pellet after cooling is expressed in °C.

[0024] Step 3: Solve the temperature field of the high-temperature pellets in the spray chamber using the lumped heat capacity method. The steps are as follows:

[0025] (1) The pellet occupies a volume of V and has a surface area of ​​A. It has no internal heat source. Under the assumption of lumped heat capacity, the pellet's cooling rate according to Newton's law is related to the temperature t. f The sprayed water exchanges heat, and the average convective heat transfer coefficient is h. According to the basic formula of heat transfer, the heat balance equation of the pellet is as follows:

[0026]

[0027] (2) Introducing excess temperature θ=tt f Then the heat balance equation is

[0028]

[0029] (3) The initial conditions are τ=0, θ=θ0=t-t0

[0030] (4) Solving the equation, we get

[0031] (5) The temperature of the pellet

[0032] Step 4: According to the formula Calculate the heat exchange efficiency of the device, where Q0 is the heat required for heat exchange between cold water and high-temperature steam, Q0 = C 水 m 水 (ts-25) Substituting Q0 into the equation yields the heat exchange efficiency of the device. This formula is used to guide the calculation of the system's heat exchange efficiency.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] 1. By setting up the impurity blocking system and the circulating material turning device in this application, on the one hand, it can ensure that the impurities inside the box are not easily flowed out with the high-temperature steam, thus improving the utilization rate of the high-temperature steam; on the other hand, it can also ensure that the actual heat exchange efficiency is improved during the heat exchange process, and more heat can be recovered in a short time.

[0035] 2. The active impurity remover can remove the collected impurities, which facilitates the actual maintenance and operation of the device and reduces the need for parts replacement.

[0036] 3. This application uses spray heat exchange for waste heat recovery, which, compared with the existing method of using airflow heat exchange for waste heat recovery, can directly improve the heat recovery efficiency and reduce the waste of waste heat. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a spray heat exchanger.

[0038] Figure 2 This is a schematic diagram of the liquid inlet nozzle installation.

[0039] Figure 3 This is a schematic diagram of the impurity blocking system.

[0040] Figure 4 This is a partial structural diagram of an impurity blocking system.

[0041] Figure 5 This is a schematic diagram of an active impurity removal system.

[0042] Figure 6 This is an exploded diagram illustrating the installation of the scraper and the barrier system.

[0043] Figure 7 This is an exploded diagram of the scraper.

[0044] Figure 8 This is a schematic diagram of the circulating material turning device.

[0045] Figure 9 This is a schematic diagram of the installation of the first extrusion plate and the second extrusion plate.

[0046] Figure 10 This is a system diagram of this application.

[0047] Figure 11 This is a schematic diagram of the heat exchange principle of the spray heat exchange box in this application.

[0048] Explanation of reference numerals in the attached drawings: 1. Box body; 11. Inlet; 12. Outlet; 13. Material placement area; 14. Liquid inlet nozzle; 2. Air outlet pipe; 3. Impurity blocking system; 4. Circulating material turning device; 31. Air guide hood; 32. Air guide plate; 33. Air guide port; 34. Mounting block; 35. Mounting groove; 36. Positioning block; 37. Impurity filter plate; 38. Positioning groove; 5. Active impurity remover; 51. Extension rod; 52. Impurity removal blades; 53. Baffle plate; 54. Collection trough; 55. Through slot; 56. Impurity removal screen; 6. Scraper; 61. 62. Mounting sleeve; 63. Drive spring; 64. Scraper; 65. First guide surface; 66. Arc-shaped guide plate; 67. Second guide surface; 68. Positioning spring; 69. Contact block; 41. Feeding belt; 42. Fixing frame; 43. First transmission rod; 44. Second transmission rod; 45. Tilting plate; 71. Contact block; 72. Arc-shaped surface; 73. Extrusion cylinder; 74. Sealing block; 75. Shovel plate; 76. Lifting spring; 77. Lifting rod; 81. Cutting block; 82. First extrusion plate; 83. Second extrusion plate; 84. Telescopic spring. Detailed Implementation

[0049] The following is in conjunction with the appendix Figures 1-9 This application will be described in further detail.

[0050] In the first aspect, this application discloses a waste heat recovery system for magnesium smelting pellets, which is mainly used in metal smelting and other fields to recover and reuse the heat of high-temperature ores. Specifically, in this embodiment, it includes a housing 1, with an inlet 11 and an outlet 12 inside the housing 1. A material storage area 13 is provided inside the housing 1, with the inlet 11 and outlet 12 located on both sides of the material storage area 13. A liquid inlet nozzle 14 is installed inside the housing 1, and an outlet pipe 2 is connected to the outlet at the top of the housing 1. In the actual heat exchange and recovery process, the high-temperature ores are transported to the material storage area 13 through the inlet 11. After closing the inlet 11 and outlet 12, water is sprayed, and the heat of the ore itself is used to heat the sprayed water into high-temperature steam. The high-temperature steam is then transported to the outside through the outlet pipe 2 for recovery and reuse.

[0051] Reference Figure 3 , Figure 4 As shown, in order to reduce the content of impurities such as dust in the high-temperature steam delivered, in this embodiment, an impurity blocking system 3 is provided inside the housing 1 facing the outlet pipe 2. The impurity blocking system 3 cleans up the dust and other impurities entering the outlet pipe 2, thereby improving the purity of the high-temperature steam.

[0052] Specifically, the impurity blocking system 3 includes a gas guide hood 31 threadedly installed at the end of the gas outlet pipe 2. The gas guide hood 31 is sealed at the gas outlet. An air guide plate 32 is inclined upward inside the gas guide hood 31. An air guide port 33 for steam to pass through is left on the upper part of the air guide plate 32. An installation block 34 is detachably slidably installed on the side of the gas guide hood 31. An installation groove 35 corresponding to the installation block 34 is opened on the gas guide hood 31. A positioning block 36 is integrally extended on the side of the installation block 34 toward the air guide port 33. An impurity filter plate 37 is installed on the positioning block 36. A positioning groove 38 that engages with the positioning block 36 is integrally provided on the air guide plate 32.

[0053] In the actual impurity removal process, the air guide hood 31 is installed at the bottom of the air outlet pipe 2, and the lower side of the air guide hood 31 is sealed and fixedly installed at the air outlet at the top of the box 1. The positioning block 36 is engaged in the positioning groove 38 through the sealing installation of the mounting block 34 and the mounting groove 35, thereby realizing the installation of the impurity filter plate 37. When high-temperature steam passes through the impurity filter plate 37, the impurities in the high-temperature steam can be filtered.

[0054] Reference Figure 5 As shown, during the process of generating high-temperature steam, certain impurities will pass through the impurity filter plate 37. Based on this, in this embodiment, an active impurity remover 5 is also provided on the upper side of the air guide plate 32. Specifically, the active impurity remover 5 includes an extension rod 51, impurity removal blades 52, a baffle plate 53, and a collection groove 54. The extension rod 51 is symmetrically installed on the upper side of the air guide plate 32. The impurity removal blades 52 are rotatably installed on the extension rod 51 and can cover the air guide port 33. The baffle plate 53 is installed on the side of the extension rod 51 facing the mounting groove 35, and the baffle plate 53 has a through groove 55 for the impurity removal blades 52 to pass through. The mounting block 34 is recessed inward to form a collection groove 54. A material collection area is formed between the baffle plate 53 and the inner wall of the air guide hood 31. The collection groove 54 is located in the material collection area. An impurity removal screen 56 is installed on the impurity removal blades 52.

[0055] In actual operation, high-temperature steam drives the impurity removal blades 52 to rotate, and the impurity removal net 56 located on the impurity removal blades 52 collects impurities. When the impurity removal blades 52 rotate into the collection area, they will fall off the impurity removal net 56 due to the lack of high-temperature steam drive and be collected in the collection trough 54. When the mounting block 34 is removed from the mounting trough 35, all the collected impurities can be removed.

[0056] Reference Figure 6 , Figure 7As shown, since impurities may adhere to the impurity removal screen 56 and are not easily removed, a scraper 6 is installed on the impurity removal blade 52 in this embodiment. Specifically, the scraper 6 includes a mounting sleeve 61, a drive spring 62, and a scraper plate 63. The mounting sleeve 61 is sleeved on the extended end of the impurity removal blade 52. The drive spring 62 is located between the mounting sleeve 61 and the impurity removal blade 52 to drive the mounting sleeve 61 to move away from the impurity removal blade 52. The scraper plate 63 is located on both sides of the mounting sleeve 61 and slides against the surface of the impurity removal screen 56. A first guide surface 65 is provided at the end of the mounting sleeve 61 away from the impurity removal blade 52.

[0057] When dust and impurities adhere to the impurity removal screen 56, the mounting sleeve 61 will come into contact with the side wall of the air guide hood 31, driving the mounting sleeve 61 to move closer to the impurity removal screen 56. At the same time, the scraper plate 63 will scrape the impurities on the impurity removal screen 56 downwards, thereby ensuring that the impurities on the impurity removal screen 56 can fall more smoothly into the collection tank 54.

[0058] Continue to refer to Figure 6 , Figure 7 As shown, in order to ensure that the mounting sleeve 61 can move more smoothly towards the impurity removal blade 52, an arc-shaped guide plate 66 is provided on the side wall of the air guide shroud 31 to cooperate with the mounting sleeve 61. The opening of the arc-shaped guide plate 66 is set towards the scraper 6, and a second guide surface 67 is provided on the upper side of the arc-shaped guide plate 66 to cooperate with the first guide surface 65. Through the cooperation of the first guide surface 65, the second guide surface 67 and the arc-shaped guide plate 66, the mounting sleeve 61 can be driven quickly and smoothly towards the impurity removal blade 52, thereby efficiently cleaning impurities.

[0059] In addition, to further ensure that impurities fall smoothly downwards, the arc-shaped guide plate 66 has several positioning grooves sequentially formed on its side wall facing the scraper 6. Positioning springs 68 are installed in the positioning grooves, and the extended ends of the positioning springs 68 are fixedly connected to a contact block 69 that elastically abuts against the mounting sleeve 61. When the mounting sleeve 61 slides inside the arc-shaped guide plate 66, it contacts the contact block 69, causing the mounting sleeve 61 to vibrate. This, in turn, allows the dust to fall downwards more efficiently, improving the actual impurity collection effect.

[0060] Reference Figure 8As shown, in this embodiment, a circulating material turning device 4 is provided on the material placement area 13 to ensure that the material can be turned over quickly, so as to form high-temperature steam with higher efficiency. In this embodiment, the circulating material turning device 4 includes a feeding belt 41, a fixed frame 42, a first transmission rod 43, a second transmission rod 44, and a turning plate 45. The feeding belt 41 is rotatably installed in the material placement area 13, the fixed frame 42 is installed inside the box 1, the first transmission rod 43 is rotatably installed on the side wall of the mounting frame and meshes with the feeding belt 41, the second transmission rod 44 is laterally rotatably installed on the upper side of the fixed frame 42 and meshes with the first transmission rod 43, and the turning plate 45 is sequentially installed on the first transmission rod 43 to realize the turning operation of the material on the feeding belt 41.

[0061] During the process of turning the material, the feeding belt 41 first moves the material. At the same time, since the feeding belt 41 meshes with the first transmission rod 43, it can drive the first transmission rod 43 to rotate, so as to realize the rotation of the second transmission rod 44 and the flipping plate 45 located on the second transmission rod 44. During the rotation of the flipping plate 45, the material located on the feeding belt 41 can be turned over, ensuring that the material can come into more full contact with water to form water vapor.

[0062] Continue to refer to Figure 8 As shown, to ensure the actual material turning effect, an abutment block 71 is slidably installed on the fixed frame 42. The upper side of the abutment block 71 has an arc-shaped surface 72. A compression cylinder 73 is also installed on the fixed frame 42. A sealing block 74 is connected below the abutment block 71 and slides in the compression cylinder 73. The extended end of the compression cylinder 73 faces the scraper plate 75 on the upper surface of the feeding belt 41, and a lifting spring 76 is installed on the upper side of the compression cylinder 73 to drive the abutment block 71 to move upward. When the turning plate 45 rotates, it can compress the abutment block 71, driving the compression block to move in the compression cylinder 73 to increase the pressure in the compression cylinder 73, driving the scraper plate 75 to extend outward. After the scraper plate 75 extends outward, the material is turned over again, ensuring sufficient material turning.

[0063] Reference Figure 9 As shown, a lifting rod 77 is provided on the upper side of the shovel plate 75. A cutting block 81 is also provided on the shovel plate 75. A first extrusion plate 82 and a second extrusion plate 83 are rotatably mounted between the cutting block 81 and the lifting rod 77. The first extrusion plate 82 and the second extrusion plate 83 are rotatably connected. The first extrusion plate 82 is rotatably connected to the cutting block 81, and the second extrusion plate 83 is rotatably connected to the lifting rod 77. A telescopic spring 84 is provided between the first extrusion plate 82 and the second extrusion plate 83, and the first extrusion plate 82 and the second extrusion plate 83 are elastic.

[0064] During the extension of the shovel plate 75, on the one hand, it can drive the lifting rod 77 and the cutting block 81 to further turn the material, and on the other hand, the first extrusion plate 82 and the second extrusion plate 83 can also drive the material to spread outward, thereby achieving a further turning effect on the material and ensuring the collection of actual heat.

[0065] Reference Figure 10 and Figure 11 As shown, this application also discloses a method for recovering waste heat from magnesium smelting pellets, as follows:

[0066] The waste heat recovery system for magnesium smelting pellets also includes a plate heat exchanger and an insulated water storage tank. After the high-temperature pellets and room-temperature water are sprayed and heat exchanged in the spray heat exchange box to generate high-temperature steam, the steam is introduced into the plate heat exchanger for heat exchange through the steam outlet pipe. This achieves the conversion of room-temperature water into constant-temperature high-temperature water through steam. The heated constant-temperature high-temperature water is then stored in the insulated water storage tank for preservation and subsequent use.

[0067] Based on the above working process and the heat transfer formula in heat transfer, the calculation method for waste heat recovery in magnesium smelting pellets includes the following steps:

[0068] Step 1: Turn on the steam pump in the high-temperature steam pipeline, measure the pressure P1 in the spray chamber, and measure the initial temperature t0 of the pellets, the volume V of the pellet tank, and the mass m of the pellets filling the pellet tank. b And height δ and surface area A, where P1 is in pa, t0 is in ℃, and V is in m. 3 ,m b The units are kg, δ is in m, and A is in m. 2 ;

[0069] Step 2: Measure the specific heat capacity c of the pellet. b The unit is J / (kg·k). Using the formula Q=cmΔt, the heat carried by a batch of high-temperature pellets in the spray chamber is calculated as c. b m b Δt, Δt = t0 - t min Q max The unit is kJ, t0 is the initial temperature of the pellet in °C, and t min The final temperature of the pellet after cooling is expressed in °C.

[0070] Step 3: Solve the temperature field of the high-temperature pellets in the spray chamber using the lumped heat capacity method. The steps are as follows:

[0071] (1) The pellet occupies a volume of V and has a surface area of ​​A. It has no internal heat source. Under the assumption of lumped heat capacity, the pellet's cooling rate according to Newton's law is related to the temperature t. fThe sprayed water exchanges heat, and the average convective heat transfer coefficient is h. According to the basic formula of heat transfer, the heat balance equation of the pellet is as follows:

[0072]

[0073] (2) Introducing excess temperature θ=tt f Then the heat balance equation is

[0074]

[0075] (3) The initial conditions are τ=0, θ=θ0=t-t0

[0076] (4) Solving the equation, we get

[0077] (5) The temperature of the pellet

[0078] Step 4: According to the formula Calculate the heat exchange efficiency of the device, where Q0 is the heat required for heat exchange between cold water and high-temperature steam, Q0 = C 水 m 水 (ts-25) Substituting Q0 into the equation yields the heat exchange efficiency of the device. This formula is used to guide the calculation of the system's heat exchange efficiency.

[0079] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A waste heat recovery system for magnesium smelting pellets, comprising a spray heat exchange box body (1), wherein the box body (1) is provided with an inlet (11) and an outlet (12), and a material placement area (13) is provided inside the box body (1), wherein the inlet (11) and the outlet (12) are located on both sides of the material placement area (13), a liquid inlet nozzle (14) is installed inside the box body (1), and an outlet pipe (2) is connected to the outlet at the top of the box body (1), characterized in that: The box (1) is equipped with an impurity blocking system (3) facing the outlet pipe (2), and a circulating material turning device (4) is provided on the material feeding area (13), wherein: The impurity blocking system (3) includes a gas guide hood (31) threaded onto the end of the gas outlet pipe (2). The gas guide hood (31) is sealed at the gas outlet. An air guide plate (32) is inclined upward inside the gas guide hood (31). An air guide port (33) for steam to pass through is left on the upper part of the air guide plate (32). An installation block (34) is detachably slidably installed on the side of the gas guide hood (31). An installation groove (35) corresponding to the installation block (34) is opened on the gas guide hood (31). A positioning block (36) is integrally extended on the side of the installation block (34) toward the air guide port (33). An impurity filter plate (37) is installed on the positioning block (36). A positioning groove (38) that engages with the positioning block (36) is integrally provided on the air guide plate (32). An active impurity remover (5) is also provided on the upper side of the air guide plate (32). The active impurity remover (5) includes an extension rod (51), impurity removal blades (52), a baffle plate (53), and a collection groove (54). The extension rod (51) is symmetrically installed on the upper side of the air guide plate (32). The impurity removal blades (52) are rotatably installed on the extension rod (51) and can cover the air guide port (33). The baffle plate (53) is installed on the side of the extension rod (51) facing the mounting groove (35), and the baffle plate (53) has a through groove (55) for the impurity removal blades (52) to pass through. The mounting block (34) is recessed inward to form a collection groove (54). A material collection area is formed between the baffle plate (53) and the inner wall of the air guide hood (31). The collection groove (54) is located in the material collection area. A cleaning screen (56) is installed on the cleaning blade (52).

2. The waste heat recovery system for magnesium smelting pellets according to claim 1, characterized in that: The impurity removal blade (52) is equipped with a scraper (6), which includes a mounting sleeve (61), a drive spring (62), and a scraper plate (63). The mounting sleeve (61) is sleeved on the extended end of the impurity removal blade (52). The drive spring (62) is located between the mounting sleeve (61) and the impurity removal blade (52) to drive the mounting sleeve (61) to move away from the impurity removal blade (52). The scraper plate (63) is located on both sides of the mounting sleeve (61) and slides against the surface of the impurity removal mesh (56). The mounting sleeve (61) has a first guide surface (65) at the end away from the impurity removal blade (52).

3. The waste heat recovery system for magnesium smelting pellets according to claim 2, characterized in that: The side wall of the air guide hood (31) is provided with an arc-shaped guide plate (66) that cooperates with the mounting sleeve (61). The opening of the arc-shaped guide plate (66) is set towards the scraper (6). The upper side of the arc-shaped guide plate (66) is provided with a second guide surface (67) that cooperates with the first guide surface (65). The arc-shaped guide plate (66) has several positioning grooves sequentially opened on the side wall facing the scraper (6). A positioning spring (68) is installed in the positioning groove. The extended end of the positioning spring (68) is fixedly connected to an abutment block (69) that elastically abuts against the mounting sleeve (61).

4. The waste heat recovery system for magnesium smelting pellets according to claim 1, characterized in that: The circulating material turning device (4) includes a feeding belt (41), a fixed frame (42), a first transmission rod (43), a second transmission rod (44), and a turning plate (45). The feeding belt (41) is rotatably installed in the material placement area (13). The fixed frame (42) is installed inside the box (1). The first transmission rod is rotatably installed on the side wall of the mounting frame and meshes with the feeding belt (41). The second transmission rod is rotatably installed on the upper side of the fixed frame (42) and meshes with the first transmission rod (43). The turning plate (45) is sequentially installed on the first transmission rod (43) to realize the turning operation of the material on the feeding belt (41).

5. The magnesium pelletizing waste heat recovery system according to claim 4, characterized in that: A contact block (71) is slidably mounted on the fixed frame (42). An arc-shaped surface (72) is provided on the upper side of the contact block (71). A compression cylinder (73) is also provided on the fixed frame (42). A sealing block (74) is connected below the contact block (71) and slides in the compression cylinder (73). The extended end of the compression cylinder (73) faces the scraper plate (75) on the upper surface of the feeding belt (41). A lifting spring (76) is installed on the upper side of the compression cylinder (73) to drive the contact block (71) to move upward.

6. The waste heat recovery system for magnesium smelting pellets according to claim 5, characterized in that: A lifting rod (77) is provided on the upper side of the shovel plate (75).

7. A waste heat recovery system for magnesium smelting pellets according to claim 6, characterized in that: The shovel plate (75) is also provided with a cutting block (81). A first extrusion plate (82) and a second extrusion plate (83) are rotatably installed between the cutting block (81) and the lifting rod (77). The first extrusion plate (82) and the second extrusion plate (83) are rotatably connected. The first extrusion plate (82) is rotatably connected to the cutting block (81), and the second extrusion plate (83) is rotatably connected to the lifting rod (77). A telescopic spring (84) is provided between the first extrusion plate (82) and the second extrusion plate (83), and the first extrusion plate (82) and the second extrusion plate (83) are elastic.

8. A method for recovering waste heat from magnesium smelting pellets, comprising the magnesium smelting pellet waste heat recovery system as described in any one of claims 1-7, characterized in that: The waste heat recovery system for magnesium smelting pellets also includes a plate heat exchanger and an insulated water storage tank. After the high-temperature pellets and room-temperature water are sprayed and heat exchanged in the spray heat exchange box to generate high-temperature steam, the steam is introduced into the plate heat exchanger for heat exchange through the steam outlet pipe. This achieves the conversion of room-temperature water into constant-temperature high-temperature water through steam. The heated constant-temperature high-temperature water is then stored in the insulated water storage tank for preservation and subsequent use. Based on the above working process and the heat transfer formula in heat transfer, the calculation method for waste heat recovery in magnesium smelting pellets includes the following steps: Step 1: Turn on the steam pump in the high-temperature steam pipeline, measure the pressure P1 in the spray chamber, and measure the initial temperature t0 of the pellets, the volume V of the pellet tank, and the mass m of the pellets filling the pellet tank. b And height δ and surface area A, where P1 is in pa, t0 is in ℃, and V is in m. 3 ,m b The units are kg, δ is in m, and A is in m. 2 ; Step 2: Measure the specific heat capacity c of the pellet. b The unit is J / (kg·k). Using the formula Q=cmΔt, the heat carried by a batch of high-temperature pellets in the spray chamber is calculated as c. b m b Δt, Δt = t0 - t min Q max The unit is kJ, t0 is the initial temperature of the pellet in °C, and t min The final temperature of the pellet after cooling is expressed in °C. Step 3: Solve the temperature field of the high-temperature pellets in the spray chamber using the lumped heat capacity method. The steps are as follows: (1) The pellet occupies a volume of V and has a surface area of ​​A. It has no internal heat source. Under the assumption of lumped heat capacity, the pellet's cooling rate according to Newton's law is related to the temperature t. f The sprayed water exchanges heat, and the average convective heat transfer coefficient is h. According to the basic formula of heat transfer, the heat balance equation of the pellet is as follows: (2) Introducing excess temperature θ=tt f Then the heat balance equation is (3) The initial conditions are τ=0, θ=θ0=t-t0 (4) Solving the equation, we get (5) The temperature of the pellet Step 4: According to the formula Calculate the heat exchange efficiency, where Q0 is the heat required for heat exchange between cold water and high-temperature steam, Q0 = C 水 m 水 (ts-25), substituting Q0 into the equation, we can obtain the heat transfer efficiency. This formula is used to guide the calculation of the heat exchange efficiency of a magnesium pellet waste heat recovery system.

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