Mannheim furnace with preheating structure and potassium sulfate preparation process

Abstract

The invention discloses a Mannheim furnace with a preheating structure and a potassium sulfate preparation process, and relates to the technical field of kilns. The Mannheim furnace is provided with a furnace charge preheating structure and a spiral heating bent pipe, the furnace charge preheating structure is used for preheating the solid potassium chloride raw material, the spiral heating bent pipe can absorb smoke heat to preheat conveyed and fed concentrated sulfuric acid, and therefore through double heat absorption and cooling of the furnace charge preheating structure and the spiral heating bent pipe, heat loss during smoke emission can be greatly reduced, and meanwhile through preheating of the potassium chloride and the concentrated sulfuric acid, the energy consumption of the furnace charge is reduced. According to the flue gas heat recycling process, the raw material heating efficiency and the reaction efficiency can be improved, the preparation efficiency and the preparation effect of potassium sulfate are further improved, a complex external boiler system and a long-distance flue gas conveying pipeline do not need to be arranged in the flue gas heat recycling process, therefore, the equipment investment and the operation cost are reduced, and efficient on-site recycling and direct utilization of flue gas waste heat are achieved.

Description

Technical Field

[0001] This invention belongs to the field of kiln technology, and specifically relates to a Mannheim furnace with a preheating structure and a potassium sulfate preparation process. Background Technology

[0002] In the chemical industry, the industrial production of potassium sulfate mainly adopts the Mannheim process. In China, this process typically uses natural gas, heavy oil, or coal gas as fuel, which is mixed with air and burned to produce high-temperature flue gas. This flue gas serves as an external heat source to heat the materials inside the Mannheim furnace, providing a continuous and stable heat of reaction for the endothermic reaction of potassium chloride and concentrated sulfuric acid to produce potassium sulfate, thereby promoting the forward reaction.

[0003] However, the combustion of these fuels produces a large amount of high-temperature flue gas, with emission temperatures typically exceeding 400°C, containing considerable thermal energy. Currently, after heating the furnace, this flue gas is often emitted directly or after simple cooling, resulting in a significant loss of waste heat into the environment, causing substantial energy waste and increasing the system's overall energy consumption and carbon emissions.

[0004] In existing waste heat recovery technologies, a common practice is to transport high-temperature flue gas to a separate boiler system, where some heat is recovered by heating water or generating steam. However, this approach has several inherent limitations: First, it requires the construction of an additional boiler room, piping system, and supporting water treatment facilities, resulting in large initial investments, extensive land use, and significant requirements for modifying the existing production layout. Second, the boiler system itself is complex to operate and maintain, further increasing operating costs. Third, because the Mannheim furnace and the waste heat boiler usually need to maintain a certain safety distance, the flue gas transport pipeline is relatively long, resulting in significant heat loss along the way, and the high energy consumption of the fans required for long-distance transport. All of these factors combined limit the actual recovery efficiency and result in poor economic performance.

[0005] Therefore, how to achieve efficient, low-cost, and integrated recovery and utilization of waste heat from Mannheim furnace flue gas without relying on a complex external boiler system has become a key technical issue for improving the energy efficiency of this process and reducing production costs and carbon footprint. Summary of the Invention

[0006] To address the problems in related technologies, this invention proposes a Mannheim furnace with a preheating structure and a potassium sulfate preparation process to overcome the aforementioned technical problems in existing related technologies.

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: The present invention is a Mannheim furnace with a preheating structure, comprising a charge preheating structure and a furnace body. Multiple burners are installed on the furnace body, and a flue pipe is provided at the top of the furnace body. A liquid feed pipe is also connected to the top of the furnace body, and a spiral heating bend is connected to the feed end of the liquid feed pipe. The spiral heating bend is fitted around the outer ring of the flue pipe. The furnace charge preheating structure includes a feeding section and a waste heat recovery section. The feeding section can be used for conveying and feeding the furnace charge, and the waste heat recovery section can recover the heat of the flue gas discharged in the flue pipe and use the recovered heat to heat the furnace charge conveyed in the feeding section. The feeding section includes a feeding conveying section, a dropping control section, and an auxiliary dropping section. The feeding conveying section can perform dropping and conveying of furnace charge. The dropping control section includes a furnace charge interception state and a dropping state. When the furnace charge is intercepted, the dropping control section can intercept and stop the furnace charge being dropped and conveyed in the feeding conveying section, so that the furnace charge is continuously preheated in the feeding conveying section. When the dropping control section is in the dropping state, the furnace charge intercepted and stopped in the feeding conveying section can continue to be dropped and conveyed downwards. The auxiliary feeding section enters the auxiliary feeding state when the feeding control section is in the furnace charge interception state. At this time, the auxiliary feeding section can impact and disperse the furnace charge that is conveyed into the feeding conveyor section so that the furnace charge falls dispersedly onto the feeding control section. The auxiliary feeding section can also enter the temporary interception state when the feeding control section is in the feeding state. At this time, the auxiliary feeding section can temporarily intercept the furnace charge that is conveyed into the feeding conveyor section, and when the feeding control section returns to the furnace charge interception state, it will feed the temporarily intercepted furnace charge onto the feeding control section. The waste heat recovery unit includes a heat exchange unit and a heating unit. The heat exchange unit can absorb the heat from the flue gas emitted from the exhaust pipe, and the heating unit can heat the feed conveying unit by absorbing the heat.

[0008] Preferably, the feeding and conveying unit includes a feeding pipe, a feeding hopper is fixedly installed at the top of the feeding pipe, a discharge hopper is provided on one side of the bottom end of the feeding pipe, a feeding port is provided on the discharge hopper, and the discharge control unit can transport the furnace material in the feeding pipe to the discharge hopper through the feeding port. The feed inlet is equipped with a sealing structure, which can seal the feed inlet when the material control unit is in the furnace material interception state, and release the seal on the feed inlet when the material control unit is in the material discharge state.

[0009] Preferably, the material discharge control unit includes a material plate and a rotary drive. The material plate is rotatably mounted on the bottom end of the feed pipe, and the material discharge end of the material plate extends into the feed inlet of the discharge hopper. The rotary drive can drive the material plate to seal against the bottom end of the feed pipe, and the rotary drive can also drive the material plate to rotate downwards towards the discharge hopper.

[0010] Preferably, the sealing structure includes a guide rail, which is fixedly installed on one side of the feed inlet. A sealing plate capable of sealing the feed inlet is slidably mounted inside the guide rail. An elastic support structure is connected to the bottom end of the sealing plate. The top end of the sealing plate abuts against the bottom surface of the material plate under the support force of the elastic support structure. When the material plate rotates and drops material, it can slide downward along the guide rail to release the seal of the sealing plate on the feed inlet. The elastic support structure includes a telescopic limiting shaft, the bottom end of which is fixedly installed on the hopper. The telescopic part at the upper end of the telescopic limiting shaft is fixedly connected to the outer wall of the sealing plate. A support spring is fitted on the telescopic limiting shaft, and the two ends of the support spring abut against the mounting connecting seats at both ends of the telescopic limiting shaft.

[0011] Preferably, the auxiliary material feeding section includes an angle adjustment drive and multiple rotating shafts. The multiple rotating shafts are equidistantly distributed and rotatably mounted on the upper end of the feed pipe, and each rotating shaft has a strip fixedly mounted on it. The angle adjustment drive can drive the multiple rotating shafts to rotate synchronously, so that the rotating shafts drive the strips to reciprocate between a horizontal and a non-horizontal state. When the strips are in a horizontal state, adjacent strips are sequentially spliced ​​together to form a horizontal interception structure, which can intercept the furnace material fed into the feed pipe. When the strips are in a non-horizontal state, a material feeding channel is left between adjacent strips for the furnace material to pass through. The strip can impact and disperse the furnace material being conveyed by the upper side; the angle adjustment drive includes a translation drive, a limiting slide rail and multiple gears, the multiple gears are respectively fixedly installed on the outer end of the corresponding rotating shaft, the limiting slide rail is fixedly installed on the outer wall of the feed pipe, and a rack that can simultaneously mesh and drive with multiple gears is slidably installed inside the limiting slide rail, the translation drive is installed at one end of the feed pipe, and a push-pull plate is fixedly installed at the telescopic end of the translation drive, the end of the push-pull plate is fixedly connected to the rack, and the translation drive is a hydraulic shaft, a cylinder or an electric telescopic shaft.

[0012] Preferably, the rotary drive component includes a hydraulic telescopic shaft, a rotating bracket, and a support shaft. The rotating bracket is rotatably mounted on one side of the material plate via the support shaft. One end of the rotating bracket is rotatably connected to the material plate, and the other end of the rotating bracket is connected to a push-pull rod. The hydraulic telescopic shaft is rotatably disposed on one side of the push-pull rod, and the telescopic end of the hydraulic telescopic shaft is rotatably connected to the push-pull rod.

[0013] Preferably, the heat exchange section includes a flue gas heat exchanger, the flue gas heat exchanger has a heat exchange channel inside, and a cold source inlet pipe and a heat source outlet pipe are fixedly installed on the outside of the flue gas heat exchanger, which are respectively connected to the two ends of the heat exchange channel. The cold source inlet pipe can transport the heat exchange medium into the heat exchange channel inside the flue gas heat exchanger. When the heat exchange medium is transported in the heat exchange channel, it absorbs heat from the flue gas and rises in temperature, and then is output to the outside from the heat source outlet pipe.

[0014] Preferably, the heating part includes an insulating shell, which is fixedly installed on the outer ring of the feed pipe to form a heating and insulating chamber around the outer ring of the feed pipe. The inlet and outlet of the heating and insulating chamber are connected to the heat source output pipe and the cold source input pipe respectively through conduits, and a circulation pump is installed on the conduits.

[0015] This invention also discloses a process for preparing potassium sulfate, the specific steps of which are as follows: Potassium chloride raw material is continuously fed into the feeding conveyor section, so that potassium chloride is fed into the furnace body along the feeding conveyor section. The auxiliary conveyor section impacts and disperses the potassium chloride raw material being fed. Then, the potassium chloride raw material is intercepted and stopped in the feeding conveyor section by the feeding control section. The heat exchange section absorbs the heat from the flue gas discharged from the exhaust pipe, and then uses the heat absorbed by the heating section to heat the feed conveyor section, so as to preheat the potassium chloride raw material intercepted and retained in the feed conveyor section. After the potassium chloride raw material is preheated, the feeding control unit enters the feeding state and continues to feed the preheated potassium chloride raw material into the furnace. At this time, the auxiliary feeding unit temporarily intercepts the potassium chloride raw material that is subsequently fed into the feeding conveyor to prevent the unpreheated potassium chloride raw material from being directly fed into the furnace. Meanwhile, concentrated sulfuric acid liquid is continuously transported into the furnace through a spiral heating bend and a liquid feed pipe, so that potassium chloride and concentrated sulfuric acid react in the furnace at high temperatures generated by the burner to produce potassium sulfate.

[0016] The present invention has the following beneficial effects: 1. In this invention, a charge preheating structure and a spiral heating bend are provided on the Mannheim furnace. The charge preheating structure absorbs the heat from the flue gas emitted from the exhaust pipe and uses this heat to preheat the solid potassium chloride raw material. The spiral heating bend absorbs the heat from the flue gas and preheats the concentrated sulfuric acid being fed into the furnace. Thus, through the dual heat absorption and cooling of the charge preheating structure and the spiral heating bend, the heat loss during flue gas emission can be greatly reduced. At the same time, by preheating the potassium chloride and concentrated sulfuric acid, the heating efficiency and reaction efficiency of the raw materials can be improved, thereby improving the preparation efficiency and effect of potassium sulfate. Moreover, this flue gas heat recovery and utilization process does not require the installation of a complex external boiler system and long-distance flue gas conveying pipelines, thereby reducing equipment investment and operating costs and realizing the efficient on-site recovery and direct utilization of flue gas waste heat.

[0017] 2. In this invention, when potassium chloride raw material is continuously fed into the furnace, the potassium chloride raw material can be intercepted and stopped in the feeding conveying section by the feeding control unit, so that the potassium chloride raw material has sufficient preheating time, thereby improving the preheating effect of the potassium chloride raw material. Moreover, the feeding control unit can repeatedly adjust and switch between the furnace charge preheating state and the feeding state, so that the feeding control unit can repeatedly and continuously convey the preheated furnace charge into the furnace, thereby realizing the continuous feeding of potassium chloride raw material.

[0018] 3. In this invention, when potassium chloride is fed into the furnace along the feeding conveyor, the auxiliary conveyor can impact and disperse the potassium chloride raw material being fed. Then, the potassium chloride raw material is intercepted by the feeding control unit and kept in the feeding conveyor for preheating. By dispersing the potassium chloride raw material, the preheating effect of the potassium chloride raw material can be improved. When the feeding control unit enters the feeding state and continues to feed the preheated potassium chloride raw material into the furnace, the auxiliary feeding unit can temporarily intercept the potassium chloride raw material that is subsequently fed into the feeding conveyor, preventing the unpreheated potassium chloride raw material from being directly fed into the furnace.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is one of the three-dimensional structural schematic diagrams of the Mannheim furnace of the present invention; Figure 2 For the present invention Figure 1 A magnified structural diagram at point A; Figure 3 This is the second three-dimensional structural schematic diagram of the Mannheim furnace of the present invention; Figure 4 For the present invention Figure 3 A magnified structural diagram at point B; Figure 5 This is the third three-dimensional structural schematic diagram of the Mannheim furnace of the present invention; Figure 6 For the present invention Figure 5 A magnified structural diagram at point C; Figure 7 For the present invention Figure 5 A magnified structural diagram at point D; Figure 8 This is the fourth three-dimensional structural schematic diagram of the Mannheim furnace of the present invention; Figure 9 For the present invention Figure 8 A magnified structural diagram at point E; Figure 10 This is the fifth three-dimensional structural schematic diagram of the Mannheim furnace of the present invention; Figure 11 For the present invention Figure 10 A magnified structural diagram at point F; Figure 12 This is one of the front structural schematic diagrams of the Mannheim furnace of the present invention; Figure 13 For the present invention Figure 12 A magnified structural diagram at point G; Figure 14 This is the second schematic diagram of the front structure of the Mannheim furnace of the present invention; Figure 15 For the present invention Figure 14 A magnified structural diagram at point H; Figure 16 This is the third schematic diagram of the front structure of the Mannheim furnace of the present invention; Figure 17 For the present invention Figure 16 A magnified structural diagram at point I.

[0022] In the diagram: 1. Furnace body; 2. Burner; 3. Exhaust pipe; 4. Feeding section; 41. Feeding pipe; 42. Feeding hopper; 43. Discharge hopper; 44. Material plate; 45. Hydraulic telescopic shaft; 46. Push-pull rod; 47. Rotating bracket; 48. Support shaft; 49. Sealing plate; 410. Guide rail; 411. Telescopic limit shaft; 412. Support spring; 413. Translation drive component; 414. Push-pull plate; 415. Limiting slide rail; 416. Rack; 417. Rotating shaft; 418. Gear; 419. Strip plate; 420. Feed inlet; 5. Waste heat recovery section; 51. Flue gas heat exchanger; 52. Cold source input pipe; 53. Heat source output pipe; 54. Insulation shell; 6. Liquid feed pipe; 61. Spiral heating bend. Detailed Implementation

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Example 1 Please see Figures 1-4 As shown, this embodiment is a Mannheim furnace with a preheating structure, including a charge preheating structure and a furnace body 1. Multiple burners 2 are installed on the furnace body 1. A flue pipe 3 is provided at the top of the furnace body 1. A liquid feed pipe 6 is also connected to and installed at the top of the furnace body 1. A spiral heating bend 61 is connected to and installed at the feed end of the liquid feed pipe 6. The spiral heating bend 61 is fitted around the outer ring of the flue pipe 3. The furnace charge preheating structure includes a feeding section 4 and a waste heat recovery section 5. The feeding section 4 can be used for conveying and feeding the furnace charge, and the waste heat recovery section 5 can recover the heat of the flue gas discharged in the flue pipe 3 and use the recovered heat to heat the furnace charge conveyed in the feeding section 4. The feeding section 4 includes a feeding conveying section, a dropping control section, and an auxiliary dropping section. The feeding conveying section can transport the furnace charge. The dropping control section includes a furnace charge interception state and a dropping state. When the furnace charge is intercepted, the dropping control section can intercept the furnace charge being transported in the feeding conveying section and keep it inside the feeding conveying section so that the furnace charge can be continuously preheated inside the feeding conveying section. When the dropping control section is in the dropping state, it can continue to transport the furnace charge intercepted and kept inside the feeding conveying section downwards. When the material control unit is in the material interception state, the auxiliary material feeding unit enters the auxiliary material feeding state. At this time, the auxiliary material feeding unit can impact and disperse the material fed into the feeding conveyor, so that the material falls dispersedly onto the material control unit. The auxiliary material feeding unit can also enter the temporary interception state when the material control unit is in the material feeding state. At this time, the auxiliary material feeding unit can temporarily intercept the material fed into the feeding conveyor, and when the material control unit returns to the material interception state, the temporarily intercepted material is fed back onto the material control unit. The waste heat recovery unit 5 includes a heat exchange unit and a heating unit. The heat exchange unit can absorb the heat of the flue gas discharged in the flue pipe 3, and the heating unit can heat the feed conveying unit by absorbing the heat. When potassium sulfate is prepared using this Mannheim furnace, potassium chloride raw material is continuously fed into the feed conveyor section, causing it to fall into the furnace body 1. An auxiliary conveyor section impacts and disperses the falling potassium chloride raw material, which is then intercepted and held within the feed conveyor section by the feeding control section. The heat exchange section absorbs heat from the exhaust gas emitted through the exhaust pipe 3, and then uses the absorbed heat to heat the feed conveyor section, preheating the potassium chloride raw material held within. After preheating, the feeding control section enters the feeding state, continuing to feed the preheated potassium chloride raw material into the furnace body 1. At this time, the auxiliary feeding section temporarily intercepts any subsequent potassium chloride raw material entering the feed conveyor section to prevent unpreheated potassium chloride from falling directly into the furnace body 1. Simultaneously, concentrated sulfuric acid liquid is continuously fed into the furnace body 1 through the spiral heating bend 61 and the liquid feed pipe 6. Inside the furnace, potassium chloride and concentrated sulfuric acid react at high temperatures generated by the combustion and heating of burner 2 to produce potassium sulfate. Among them, the heat loss during flue gas emission can be greatly reduced by the dual heat absorption and cooling of the furnace charge preheating structure and the spiral heating bend 61. At the same time, the preheating of potassium chloride and concentrated sulfuric acid can improve the heating efficiency and reaction efficiency of raw materials, thereby improving the preparation efficiency and effect of potassium sulfate. Moreover, this flue gas heat recovery and utilization process does not require the setting of a complex external boiler system and long-distance flue gas transmission pipeline, thereby reducing equipment investment and operating costs, and realizing the efficient on-site recovery and direct utilization of flue gas waste heat. When potassium chloride raw material is continuously fed into the furnace body 1, the potassium chloride raw material can be intercepted and stopped in the feeding conveyor by the feeding control unit, so that the potassium chloride raw material has sufficient preheating time, thereby improving the preheating effect of the potassium chloride raw material. The feeding control unit can repeatedly adjust and switch between the furnace preheating state and the feeding state, so that the feeding control unit can repeatedly and continuously feed the preheated furnace material into the furnace body 1, thereby realizing the continuous feeding of potassium chloride raw material. The auxiliary conveying section impacts and disperses the potassium chloride raw material during feeding, making its distribution more uniform within the feeding conveying section and improving its preheating effect. When the feeding control section enters the feeding state and continues to feed the preheated potassium chloride raw material into the furnace body, the auxiliary feeding section can also temporarily intercept the potassium chloride raw material subsequently fed into the feeding conveying section, preventing unpreheated potassium chloride raw material from being directly fed into the furnace body 1.

[0026] Example 2 Please see Figures 1-6 , Figures 10-17As shown, the difference between this embodiment and the above embodiment is that the feeding and conveying unit includes a feeding pipe 41, a feeding hopper 42 is fixedly installed at the top of the feeding pipe 41, a dropping hopper 43 is provided on one side of the bottom end of the feeding pipe 41, and a feeding port 420 is provided on the dropping hopper 43. The dropping control unit can transport the furnace material in the feeding pipe 41 to the dropping hopper 43 through the feeding port 420. A sealing structure is provided inside the feed inlet 420. The sealing structure can seal the feed inlet 420 when the material control unit is in the furnace material interception state, and the sealing structure can release the seal on the feed inlet 420 when the material control unit is in the material discharge state. The material discharge control unit includes a material plate 44 and a rotary drive. The material plate 44 is rotatably mounted on the bottom end of the feed pipe 41, and the material discharge end of the material plate 44 extends into the feed inlet 420 of the discharge hopper 43. The rotary drive can drive the material plate 44 to seal against the bottom end of the feed pipe 41, and the rotary drive can also drive the material plate 44 to rotate downwards towards the discharge hopper 43. The rotary drive includes a hydraulic telescopic shaft 45, a rotating bracket 47, and a support shaft 48. The rotating bracket 47 is rotatably mounted on one side of the material plate 44 via the support shaft 48. One end of the rotating bracket 47 is rotatably connected to the material plate 44, and the other end of the rotating bracket 47 is connected to and mounted with a push-pull rod 46. The hydraulic telescopic shaft 45 is rotatably mounted on one side of the push-pull rod 46, and the telescopic end of the hydraulic telescopic shaft 45 is rotatably connected to the push-pull rod 46. When potassium chloride raw material is fed, it is continuously fed into the feed hopper 42 by a feeding conveyor belt and other feeding equipment. The falling potassium chloride raw material is dispersed by the auxiliary conveying section and falls onto the material plate 44. The material plate 44 intercepts and retains the potassium chloride raw material in the feed pipe 41 to continuously preheat the potassium chloride raw material. After the potassium chloride raw material is preheated, the hydraulic telescopic shaft 45 extends, and the push-pull rod 46 pushes the rotating bracket 47 to rotate around the support shaft 48. At this time, the rotating bracket 47 drives the unloading end of the material plate 44 to gradually rotate downward, and at the same time, the material plate 44 moves the sealing structure downward to abut against it. This allows the feed inlet 420 to gradually open. Then, the potassium chloride raw material on the material plate 44 is transported along the inclined surface of the top surface of the material plate 44 through the feed inlet 420 to the discharge hopper 43, and then discharged from the discharge hopper 43 into the furnace body 1. After the discharge is completed, the hydraulic telescopic shaft 45 retracts and resets, and the rotating bracket 47 is pulled and rotated and reset by the push-pull rod 46 with the support shaft 48 as the fulcrum. At this time, the rotating bracket 47 drives the discharge end of the material plate 44 to gradually rotate and reset upward, so that the material plate 44 re-seals and abuts against the bottom end of the feed pipe 41. At the same time, the sealing structure moves upward and resets to re-seal the feed inlet 420. By setting a material plate 44 that can be repeatedly adjusted between a parallel sealing state and an inclined feeding state, the potassium chloride raw material fed into the feed pipe 41 can be intercepted, allowing the potassium chloride raw material sufficient preheating time and thus improving the preheating effect of the potassium chloride raw material. By setting a sealing structure in the feed inlet 420, the feed inlet 420 can be sealed when the potassium chloride raw material is preheated, preventing heat from the furnace body 1 from escaping out of the feed inlet 420, which is beneficial to improving the heat preservation effect of the furnace body. When feeding, the rotating and inclined material plate 44 can abut and open the sealing structure, so that the potassium chloride raw material on the material plate 44 can be directly conveyed through the feed inlet 420.

[0027] Example 3 Please see Figure 5 , Figure 6 , Figure 10 , Figure 11 As shown, the difference between this embodiment and the above embodiment is that the sealing structure includes a guide rail 410, which is fixedly installed on one side of the feed inlet 420. A sealing plate 49 that can abut and seal the feed inlet 420 is slidably mounted inside the guide rail 410. An elastic support structure is connected and installed at the bottom end of the sealing plate 49. The top end of the sealing plate 49 abuts against the bottom surface of the material plate 44 under the support force of the elastic support structure. When the material plate 44 rotates and drops material, the sealing plate 49 can slide downward along the guide rail 410 to release the seal of the sealing plate 49 on the feed inlet 420. The elastic support structure includes a telescopic limiting shaft 411, the bottom end of which is fixedly installed on the dropping hopper 43. The telescopic part at the upper end of the telescopic limiting shaft 411 is fixedly connected to the outer wall of the sealing plate 49. A support spring 412 is fitted on the telescopic limiting shaft 411. The two ends of the support spring 412 abut against the mounting connecting seats at both ends of the telescopic limiting shaft 411.

[0028] When the material plate 44 is in a horizontal sealed state, the top of the sealing plate 49 abuts against the bottom surface of the material plate 44 under the pushing support of the support spring 412, and at this time the sealing plate 49 seals the feed inlet 420. When the material plate 44 rotates and tilts to drop material, the dropping end of the material plate 44 moves downward and abuts the sealing plate 49 downward, so that the upper end of the feed inlet 420 gradually opens. At this time, the potassium chloride raw material on the top surface of the material plate 44 can be transported to the dropping hopper 43 along the opening position of the upper end of the feed inlet 420, and then sent to the furnace body 1 by the dropping hopper 43.

[0029] Example 4 Please see Figure 5 , Figures 7-9 , Figures 14-17As shown, the difference between this embodiment and the above embodiment is that the auxiliary material feeding section includes an angle adjustment drive and multiple rotating shafts 417. The multiple rotating shafts 417 are equidistantly distributed and rotatably mounted inside the upper end of the feed pipe 41, and each rotating shaft 417 is fixedly mounted with a strip 419. The angle adjustment drive can drive the multiple rotating shafts 417 to rotate synchronously, so that the rotating shafts 417 drive the strips 419 to reciprocate between a horizontal state and a non-horizontal state (inclined or vertical state). When the strips 419 are in a horizontal state, adjacent strips 419 are sequentially spliced ​​together to form a horizontal interception structure, which can intercept the furnace material conveyed into the feed pipe 41. When the strips 419 are in a non-horizontal state, space is left between adjacent strips 419 for the furnace material to pass through. The material discharge channel is provided, and the strip 419 can impact and disperse the furnace material being discharged through the upper side. The angle adjustment drive includes a translation drive 413, a limiting slide rail 415, and multiple gears 418. The multiple gears 418 are respectively fixedly installed on the outer end of the corresponding rotating shaft 417. The limiting slide rail 415 is fixedly installed on the outer wall of the feed pipe 41. A rack 416 that can simultaneously mesh and drive with multiple gears 418 is slidably installed inside the limiting slide rail 415. The translation drive 413 is installed at one end of the feed pipe 41, and a push-pull plate 414 is fixedly installed at the telescopic end of the translation drive 413. The end of the push-pull plate 414 is fixedly connected to the rack 416. The translation drive 413 is a hydraulic shaft, a cylinder, or an electric telescopic shaft.

[0030] When the material discharge control unit preheats and retains the potassium chloride raw material, the strip plate 419 is in a non-horizontal state (inclined or vertical). At this time, the potassium chloride raw material discharged from the upper feed hopper 42 into the feed pipe 41 collides and impacts with the upper side of the strip plate 419 as it falls, so that the potassium chloride raw material is evenly and loosely distributed in the feed pipe 41, thereby improving the preheating effect of the potassium chloride raw material. When the preheating is completed and the material discharge control unit tilts to discharge the material, the translation drive 413 drives the push-pull plate 414 to flatten. The push-pull plate 414 drives the rack 416 to slide along the limit slide rail 415. At this time, the rack 416 meshes and drives multiple gears 418 to rotate synchronously, so that the gears 418 drive the rotating shaft 417 and the strip 419 to rotate, so that the multiple strips 419 are rotated and adjusted to a horizontal state. At this time, the multiple strips 419 are spliced ​​together in sequence to form a horizontal interception structure, which supports and intercepts the potassium chloride raw material fed by the feed hopper 42, preventing the potassium chloride raw material from being directly fed into the furnace body 1 without preheating. When the material feeding control unit enters the furnace charge preheating state, the translation drive 413 drives the push-pull plate 414 to reverse translation and reset, so as to drive the strip plate 419 to rotate and reset to return to the non-horizontal state. At this time, the potassium chloride raw material intercepted on the strip plate 419 falls downwards into the material feeding control unit for preheating. Furthermore, the strip 419 can keep the upper end of the feed pipe 41 in a semi-sealed state to improve the heat preservation and preheating effect of the feed pipe 41 and reduce heat loss.

[0031] Example 5 Please see Figures 1-4 As shown, the difference between this embodiment and the above embodiment is that the heat exchange section includes a flue gas heat exchanger 51, the flue gas heat exchanger 51 is provided with a heat exchange channel inside, and a cold source input pipe 52 and a heat source output pipe 53, which are respectively connected to the two ends of the heat exchange channel, are fixedly installed on the outside of the flue gas heat exchanger 51. The cold source input pipe 52 can transport the heat exchange medium into the heat exchange channel inside the flue gas heat exchanger 51. When the heat exchange medium is transported in the heat exchange channel, it can absorb the heat of the flue gas and rise in temperature, and then be output to the outside from the heat source output pipe 53. The heating section includes an insulation shell 54, which is fixedly installed on the outer ring of the feed pipe 41 to form a heating and insulation chamber around the outer ring of the feed pipe 41. The inlet and outlet of the heating and insulation chamber are respectively connected to the heat source output pipe 53 and the cold source input pipe 52 through conduits, and a circulation pump is installed on the conduits.

[0032] The heating and insulation chamber, cold source input pipe 52, heat source output pipe 53, and heat exchange channel are connected by conduits to form a circulating heat exchange channel. The circulating pump drives the heat exchange medium (water or oil) to circulate in the circulating heat exchange channel. When the heat exchange medium flows into the heat exchange channel, it exchanges heat with the flue gas through the metal heat exchange plate in the flue gas heat exchanger 51, thereby absorbing heat from the flue gas and raising its temperature. The heated heat exchange medium is then transported to the heating and insulation chamber to heat and insulate the feed pipe 41. The feed pipe 41 is made of a metal heat-conducting material, which can improve the heat conduction effect and make the feed pipe 41 heat up quickly, thereby preheating the potassium chloride raw material in the feed pipe 41.

[0033] Example 6 This embodiment discloses a potassium sulfate preparation process, the specific steps of which are as follows: Potassium chloride raw material is continuously fed into the feeding conveyor section, so that potassium chloride is fed into the furnace body 1 along the feeding conveyor section. The auxiliary conveyor section impacts and disperses the potassium chloride raw material being fed. Then, the potassium chloride raw material is intercepted and stopped in the feeding conveyor section by the feeding control section. The heat exchange section absorbs the heat from the flue gas discharged from the exhaust pipe 3, and then uses the heat absorbed by the heating section to heat the feed conveyor section, so as to preheat the potassium chloride raw material intercepted and retained in the feed conveyor section. After the potassium chloride raw material is preheated, the feeding control unit enters the feeding state and continues to feed the preheated potassium chloride raw material into the furnace body 1. At this time, the auxiliary feeding unit temporarily intercepts the potassium chloride raw material that is subsequently fed into the feeding conveying unit to prevent the unpreheated potassium chloride raw material from being directly fed into the furnace body 1. Meanwhile, concentrated sulfuric acid liquid is continuously transported into the furnace body 1 through the spiral heating bend 61 and the liquid feed pipe 6, so that potassium chloride and concentrated sulfuric acid react in the furnace body 1 at the high temperature generated by the combustion and heating of the burner 2 to produce potassium sulfate.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.

Claims

1. A furnace charge preheating structure, comprising a feeding section and a waste heat recovery section, wherein the feeding section is used for conveying and feeding furnace charge, and the waste heat recovery section is used to recover the heat of the flue gas emitted from the furnace and to heat the furnace charge conveyed in the feeding section using the recovered heat; The feeding section includes a feeding conveying section, a dropping control section, and an auxiliary dropping section. The feeding conveying section can perform dropping and conveying of furnace charge. The dropping control section includes a furnace charge interception state and a dropping state. When the furnace charge is intercepted, the dropping control section can intercept and stop the furnace charge being dropped and conveyed in the feeding conveying section, so that the furnace charge is continuously preheated in the feeding conveying section. When the dropping control section is in the dropping state, the furnace charge intercepted and stopped in the feeding conveying section can continue to be dropped and conveyed downwards. The auxiliary feeding section enters the auxiliary feeding state when the feeding control section is in the furnace charge interception state. At this time, the auxiliary feeding section can impact and disperse the furnace charge that is conveyed into the feeding conveyor section so that the furnace charge falls dispersedly onto the feeding control section. The auxiliary feeding section can also enter the temporary interception state when the feeding control section is in the feeding state. At this time, the auxiliary feeding section can temporarily intercept the furnace charge that is conveyed into the feeding conveyor section, and when the feeding control section returns to the furnace charge interception state, it will feed the temporarily intercepted furnace charge onto the feeding control section. The waste heat recovery unit includes a heat exchange unit and a heating unit. The heat exchange unit can absorb the heat from the flue gas emitted from the furnace, and the heating unit can heat the feed conveying unit by absorbing the heat.

2. The furnace charge preheating structure according to claim 1, characterized in that: The feeding and conveying unit includes a feeding pipe, a feeding hopper is fixedly installed at the top of the feeding pipe, a dropping hopper is provided on one side of the bottom end of the feeding pipe, and a feeding port is provided on the dropping hopper. The dropping control unit can transport the furnace material in the feeding pipe to the dropping hopper through the feeding port. The feed inlet is equipped with a sealing structure, which can seal the feed inlet when the material control unit is in the furnace material interception state, and release the seal on the feed inlet when the material control unit is in the material discharge state.

3. The furnace charge preheating structure according to claim 2, characterized in that: The material discharge control unit includes a material plate and a rotary drive. The material plate is rotatably mounted on the bottom end of the feed pipe, and the material discharge end of the material plate extends into the feed inlet of the discharge hopper. The rotary drive can drive the material plate to seal against the bottom end of the feed pipe, and the rotary drive can also drive the material plate to rotate downwards towards the discharge hopper.

4. The furnace charge preheating structure according to claim 3, characterized in that: The sealing structure includes a guide rail, which is fixedly installed on one side of the feed inlet. A sealing plate that can abut and seal the feed inlet is mounted in the guide rail. An elastic support structure is connected to the bottom end of the sealing plate. The top end of the sealing plate abuts against the bottom surface of the material plate under the support force of the elastic support structure. When the material plate rotates and drops material, it can slide and displace the sealing plate downward along the guide rail to release the seal of the sealing plate on the feed inlet.

5. The furnace charge preheating structure according to claim 2, characterized in that: The auxiliary material feeding section includes an angle adjustment drive and multiple rotating shafts. The multiple rotating shafts are equidistantly distributed and rotatably installed inside the upper end of the feed pipe, and each rotating shaft is fixedly mounted with a strip plate. The angle adjustment drive can drive the multiple rotating shafts to rotate synchronously, so that the rotating shafts drive the strip plates to reciprocate between a horizontal state and a non-horizontal state. When the strip plate is in a horizontal state, adjacent strip plates are spliced ​​together in sequence to form a horizontal interception structure, which can intercept the furnace material conveyed into the feed pipe. When the strip plate is in a non-horizontal state, a material feeding channel is left between adjacent strip plates for the furnace material to pass through, and the strip plate can impact and disperse the furnace material conveyed by the material feeding through its upper side.

6. The furnace charge preheating structure according to claim 3, characterized in that: The rotary drive component includes a hydraulic telescopic shaft, a rotating bracket, and a support shaft. The rotating bracket is rotatably mounted on one side of the material plate via the support shaft. One end of the rotating bracket is rotatably connected to the material plate, and the other end of the rotating bracket is connected to a push-pull rod. The hydraulic telescopic shaft is rotatably mounted on one side of the push-pull rod, and the telescopic end of the hydraulic telescopic shaft is rotatably connected to the push-pull rod.

7. The furnace charge preheating structure according to claim 2, characterized in that: The heat exchange section includes a flue gas heat exchanger, which has a heat exchange channel inside. A cold source inlet pipe and a heat source outlet pipe, which are respectively connected to both ends of the heat exchange channel, are fixedly installed on the outside of the flue gas heat exchanger. The cold source inlet pipe can transport the heat exchange medium into the heat exchange channel inside the flue gas heat exchanger. When the heat exchange medium is transported in the heat exchange channel, it absorbs heat from the flue gas and rises in temperature, and then is output to the outside from the heat source outlet pipe.

8. The furnace charge preheating structure according to claim 7, characterized in that: The heating unit includes an insulating shell, which is fixedly installed on the outer ring of the feed pipe to form a heating and insulating chamber around the outer ring of the feed pipe. The inlet and outlet of the heating and insulating chamber are connected to the heat source output pipe and the cold source input pipe respectively through conduits, and a circulation pump is installed on the conduits.

9. A Mannheim furnace with a preheating structure, comprising the charge preheating structure as described in any one of claims 1-8, characterized in that: It also includes a furnace body, on which multiple burners are installed. A flue pipe is provided at the top of the furnace body, and a liquid feed pipe is also connected to the top of the furnace body. A spiral heating bend is connected to the feed end of the liquid feed pipe and is fitted around the outer ring of the flue pipe.

10. A potassium sulfate preparation process, using a Mannheim furnace with a preheating structure as described in claim 9, characterized in that, The specific steps are as follows: Potassium chloride raw material is continuously fed into the feeding conveyor section, so that potassium chloride is fed into the furnace body along the feeding conveyor section. The auxiliary conveyor section impacts and disperses the potassium chloride raw material being fed. Then, the potassium chloride raw material is intercepted and stopped in the feeding conveyor section by the feeding control section. The heat exchange section absorbs the heat from the flue gas discharged from the exhaust pipe, and then uses the heat absorbed by the heating section to heat the feed conveyor section, so as to preheat the potassium chloride raw material intercepted and retained in the feed conveyor section. After the potassium chloride raw material is preheated, the feeding control unit enters the feeding state and continues to feed the preheated potassium chloride raw material into the furnace. At this time, the auxiliary feeding unit temporarily intercepts the potassium chloride raw material that is subsequently fed into the feeding conveyor to prevent the unpreheated potassium chloride raw material from being directly fed into the furnace. Meanwhile, concentrated sulfuric acid liquid is continuously transported into the furnace through a spiral heating bend and a liquid feed pipe, so that potassium chloride and concentrated sulfuric acid react at high temperatures generated by the burner in the furnace to produce potassium sulfate.

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