A potassium nitrate purification device

Abstract

The present application relates to nitrate production technical field, specifically to a kind of potassium nitrate purification device, including the dissolution tank, filter device, crystallization kettle, centrifuge in series by pipeline sequentially, and with steam jacket dryer.The first jacket of dissolution tank is connected heat source by circulation pipeline;Centrifuge liquid outlet is sequentially connected cyclone separator, ceramic membrane filter, cation resin column, first temporary storage tank, heat source, and first heat exchanger, second heat exchanger are sequentially installed between the heat medium import of first temporary storage tank and heat source.Steam outlet pipeline of steam jacket is connected the hot medium import of first heat exchanger, and first heat exchanger is connected second temporary storage tank by pipeline, and second temporary storage tank is connected heat source by pipeline again.Dryer waste gas is connected second vacuum unit, and second vacuum unit pipeline is connected the hot medium import of second heat exchanger, and second heat exchanger is connected second temporary storage tank.The present application realizes the synergistic promotion of potassium nitrate purification efficiency, product purity, resource utilization and energy economy.

Description

Technical Field

[0001] This invention relates to the field of nitrate production technology, specifically to a potassium nitrate purification device. Background Technology

[0002] Potassium nitrate, as an important inorganic chemical raw material, is widely used in agriculture, industry, food processing, and medicine. Its purity directly determines the quality and effectiveness of downstream applications; therefore, industrial purification technology is one of the core links in the development of the potassium nitrate industry. Currently, the mainstream potassium nitrate purification processes in the industry have shortcomings in process integration and the sophistication of core equipment design. This leads to a prominent contradiction between efficiency, purity, resource utilization, and energy consumption during the purification process, making it difficult to meet the demands of industrial production for high efficiency, high purity, and low energy consumption. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a potassium nitrate purification device, specifically achieved through the following technical solution:

[0004] A potassium nitrate purification apparatus includes a dissolving tank, a filtration device, a crystallizing kettle, a centrifuge, and a dryer heated by a steam jacket, connected in series via pipelines. The dissolving tank includes a first tank body with a first jacket. The first jacket is connected to a heat source via a circulation pipeline. The liquid outlet of the centrifuge is connected in sequence via pipelines to a hydrocyclone separator, a ceramic membrane filter, a cation exchange resin column, a first temporary storage tank, and the heat medium inlet of the heat source. A second heat exchanger and a first heat exchanger are sequentially installed on the pipeline between the first temporary storage tank and the heat medium inlet. The steam outlet of the steam jacket is connected to the heat medium inlet of the first heat exchanger via the twentieth pipe. The heat medium outlet of the first heat exchanger is connected to the liquid inlet of the second temporary storage tank via the sixteenth pipe. The liquid outlet of the second temporary storage tank is connected to the heat medium inlet via the twenty-first pipe. The exhaust gas outlet of the dryer is connected to the second vacuum unit via the twenty-second pipe. The second vacuum unit is connected to the heat medium inlet of the second heat exchanger via the eighteenth pipe. The heat medium outlet of the second heat exchanger is connected to the liquid inlet of the second temporary storage tank via the seventeenth pipe.

[0005] The first tank has a coil installed inside by a bracket. The bottom of the coil is fixedly connected to the first end of the inlet pipe. The second end of the inlet pipe extends from the top of the first tank and is connected to the heat medium outlet of the heat source through the tenth pipe. The top of the coil is fixedly connected to the first end of the outlet pipe. The second end of the outlet pipe extends out of the first tank and is connected to the solvent inlet on the first tank through a connecting pipe. A first three-way valve is installed on the connecting pipe. The first three-way valve is connected to the first inlet of the first jacket through the seventh pipe. The first outlet of the first jacket is connected to the heat medium inlet of the heat source through the eighth pipe.

[0006] The first tank is equipped with a first stirring shaft driven by a first motor, and a first stirring paddle is fixedly installed on the first stirring shaft.

[0007] An exhaust pipe is installed on the top of the first tank.

[0008] The first stirring paddle is located within the cylindrical space formed by the coil.

[0009] The filtration device includes a filter tank. The inlet of the filter tank is connected to a dissolving tank via a flow pipe equipped with a third valve body. An overflow port is provided on the side wall of the filter tank. The overflow port is connected to a third inlet located at the top of a buffer tank via a twenty-fourth pipe. The vent at the top of the buffer tank is connected to a first vacuum unit via a sixth pipe. The bottom of the filter tank is connected to a crystallizing vessel via a fourth pipe. A second valve body is installed on the fourth pipe. The third outlet at the bottom of the buffer tank is connected to the fourth pipe via a fifth pipe. A first valve body is installed on the fifth pipe. The connection point between the fifth and fourth pipes is between the second valve body and the crystallizing vessel.

[0010] The filter tank includes a liquid storage tank, the top of which is detachably covered. A disc-shaped filter plate is fixedly installed inside the liquid storage tank, and a filter membrane is laid on top of the filter plate. The overflow port is located below the filter plate.

[0011] The liquid storage tank is equipped with a second insulation layer, and the buffer tank is equipped with a first insulation layer.

[0012] The crystallizing vessel is equipped with a second jacket. The upper part of the second jacket is provided with a second liquid outlet, and the lower part is provided with a fourth liquid inlet. The fourth liquid inlet is connected to the refrigerant outlet of the cold source through a third pipeline, and the refrigerant inlet of the cold source is connected to the second liquid outlet through a second pipeline.

[0013] A fourth liquid level sensor is installed in the dissolving tank, a third liquid level sensor is installed in the crystallizing vessel, a first liquid level sensor is installed in the filtering tank, and a second liquid level sensor is installed in the buffer tank; the second, first, third, and fourth liquid level sensors are all electrically connected to the controller.

[0014] The technical solution of this invention has the following advantages:

[0015] The potassium nitrate purification device of this invention achieves a synergistic improvement in potassium nitrate purification efficiency, product purity, resource utilization, and energy economy by constructing an integrated process of dissolution, filtration, crystallization, separation, drying, and recycling, and by combining the refined structural design of each core device. It effectively solves the technical defects commonly found in existing potassium nitrate purification technologies, such as uneven dissolution, low filtration efficiency, serious waste of mother liquor, and high energy consumption, and provides an efficient and environmentally friendly technical solution for the industrial purification of potassium nitrate. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the dissolving tank.

[0019] Figure 3 This is a schematic diagram of the top structure of the dissolving tank;

[0020] Figure 4 This is a schematic diagram of the filtration device.

[0021] Figure 5 for Figure 4 Schematic diagram of the structure at point A;

[0022] Figure 6 This is a schematic diagram of the vessel body.

[0023] In the diagram, 1-dryer, 2-heat source pipe, 3-first pipe, 4-second pipe, 5-third pipe, 6-cold source, 7-crystallizer, 8-fourth pipe, 9-first valve body, 10-fifth pipe, 11-second valve body, 12-filter device, 13-sixth pipe, 14-first vacuum unit, 15-seventh pipe, 16-dissolving tank, 17-eighth pipe, 18-ninth pipe, 19-tenth pipe, 20-heat source, 21-eleventh pipe, 22-twelfth pipe, 23-cyclone separator, 24-thirteenth pipe, 25- Ceramic membrane filter, 26-Fourteenth pipe, 27-First heat exchanger, 28-Fifteenth pipe, 29-Sixteenth pipe, 30-Second heat exchanger, 31-Seventeenth pipe, 32-Eighteenth pipe, 33-Cation resin column, 34-Nineteenth pipe, 35-First storage tank, 36-Twentieth pipe, 37-Second vacuum unit, 38-Twenty-first pipe, 39-Second storage tank, 40-Twenty-second pipe, 41-Centrifuge, 42-Twenty-third pipe, 43-First tank body, 44-First inlet, 45-First end cap 46-Exhaust pipe, 47-First motor, 48-First base, 49-First stirring shaft, 50-Liquid inlet pipe, 51-First liquid outlet, 52-First jacket, 53-Coil, 54-Support, 55-First discharge port, 56-First liquid inlet, 57-Liquid outlet pipe, 58-Connecting pipe, 59-First three-way valve, 60-Connecting block, 61-Second liquid inlet, 62-Installation interface, 63-Buffer tank, 64-First insulation layer, 65-Exhaust port, 66-Third liquid inlet, 67-Twenty-fourth pipeline, 68-Overflow port, 69-First... 70-Top cover, 71-First solution inlet, 72-Second solution inlet, 73-Second storage tank flange, 74-Storage tank, 75-First liquid level sensor, 76-Second insulation layer, 77-Second discharge port, 78-Filter plate, 79-Filter membrane, 80-Sealing ring, 81-Bottle body, 82-Manhole, 83-Second base, 84-Second motor, 85-Second feed inlet, 86-Second stirring shaft, 87-Second stirring paddle, 88-Second liquid outlet, 89-Second jacket, 90-Fourth discharge port, 91-Fourth liquid inlet. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the module or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In this embodiment, unless otherwise specified, the connections between pipelines, between pipelines and corresponding equipment, and between interfaces and valves are all achieved through flanges.

[0029] As attached Figure 1 As shown, the present invention provides a potassium nitrate purification device, including a dissolving tank 16, a filtering device 12, a crystallizing kettle 7, a centrifuge 41, and a dryer 1 connected in series by pipelines; the potassium nitrate to be purified is heated and redissolved in the dissolving tank 16, the potassium nitrate solution enters the filtering device 12 for filtration, and then the potassium nitrate solution enters the crystallizing kettle 7 for cooling and recrystallization, and then the slurry enters the centrifuge 41 for solid-liquid separation, the solid enters the dryer 1 for drying, and the mother liquor is reused.

[0030] The structure of dissolving tank 16 is shown in the attached figure. Figure 2 and attached Figure 3 As shown, it includes a first tank body 43, and a first jacket 52 is fixedly installed on the lower part of the first tank body 43. The upper part of the first jacket 52 is provided with a first liquid outlet 51, and the lower part is provided with a first liquid inlet 56. The first jacket 52 is used to introduce heat medium to keep the inside of the first tank body 43 warm and heat it.

[0031] The bottom of the first tank 43 is provided with a first discharge port 55.

[0032] Inside the first tank 43, a coil 53 is installed via a bracket 54. The bottom of the coil 53, i.e. the first end, is fixedly connected to the first end of the inlet pipe 50. The second end of the inlet pipe 50 extends along the height direction of the first tank 43 and passes through the second inlet port 61 at the top of the first tank 43. The inlet pipe 50 and the second inlet port 61 are connected by a flange.

[0033] The top of the coil 53, i.e. the second end, is fixedly connected to the first end of the outlet pipe 57. The second end of the outlet pipe 57 passes through the first tank 43 and is connected to the solvent inlet on the first tank 43 through the connecting pipe 58. A first three-way valve 59 is installed on the connecting pipe 58.

[0034] Four connecting blocks 60 are fixedly installed at the top center of the first tank body 43. The connecting blocks 60 are fixedly connected to the bottom of the first base 48 by bolts. The first motor 47 is installed on the top of the first base 48 by bolts.

[0035] The output end of the first motor 47 is fixedly connected to the first end of the first stirring shaft 49 via the first coupling. The second end of the first stirring shaft 49 is inserted into the interior of the first tank 43 and a first stirring paddle is fixedly installed thereon.

[0036] The first stirring blade is located inside the coil 53, that is, the first stirring blade is located in the cylindrical space formed by the coil 53.

[0037] The coil 53 is fitted with the inner wall of the first tank 43 with a clearance fit.

[0038] As attached Figure 2 As shown, the top of the first tank 43 is also provided with four installation interfaces 62, which are used to install a temperature sensor, a fourth liquid level sensor, an exhaust pipe 46, and a sampling port, respectively.

[0039] The first end of the exhaust pipe 46 is connected to the corresponding mounting interface 62 via a flange.

[0040] The top of the first tank 43 is provided with a first feed inlet 44, and a first end cap 45 is hinged to the first feed inlet 44. The first feed inlet 44 is used to add potassium nitrate into the first tank 43.

[0041] As attached Figure 1 As shown, the second end of the inlet pipe 50 is connected to the first end of the tenth pipe 19 via a flange. The second end of the tenth pipe 19 is connected to the heat medium outlet of the heat source 20. The first three-way valve 59 is connected to the first inlet 56 via the seventh pipe 15. The first outlet 51 is connected to the heat medium inlet of the heat source 20 via the eighth pipe 17. The heat medium outlet of the heat source 20 is also connected to one end of the ninth pipe 18.

[0042] Heat source 20 is used to heat the heat medium, and the ninth pipe 18 is used to replenish the heat source 20 with new heat medium. In this embodiment, the heat medium is a solvent for dissolving potassium nitrate.

[0043] The first discharge port 55 is connected to the filter device 12 through a transfer pipe, and a third valve body is installed on the transfer pipe.

[0044] When potassium nitrate needs to be dissolved, heat source 20 discharges heat medium into coil 53 through tenth pipe 19. When the heat medium flows through coil 53, it preheats the first tank 43. The heat medium flows out from the second end of outlet pipe 57 and enters the first tank 43 through connecting pipe 58 and solvent inlet in sequence.

[0045] When the fourth liquid level sensor detects that the solvent in the first tank 43 has reached the predetermined liquid level, the first three-way valve 59 is activated. The solvent no longer enters the first tank 43, but enters the first jacket 52 through the seventh pipe 15, and then returns to the heat source 20 through the eighth pipe 17. At this time, the solvent plays the role of heat preservation and heating.

[0046] Add the potassium nitrate to be dissolved into the first tank 43, start the first motor 47, and stir until fully dissolved.

[0047] The structure of the filter device 12 is shown in the attached figure. Figure 4 and attached Figure 5 As shown, it includes a buffer tank 63 and a filter tank. The filter tank includes a liquid storage tank 74 with a second insulation layer 76 installed. A second storage tank flange 73 is fixedly installed on the top of the liquid storage tank 74. The second storage tank flange 73 is bolted to a first storage tank flange 69 fixedly installed on the top cover 70.

[0048] A sealing ring 80 is installed between the second storage tank flange 73 and the first storage tank flange 69.

[0049] The top of the cover 70 is provided with a first solution inlet 71 and a second solution inlet 72. The first solution inlet 71 and the second solution inlet 72 are respectively connected to the corresponding dissolving tank 16 through corresponding transfer pipes, that is, each filter tank can be connected to at least two dissolving tanks 16.

[0050] A disc-shaped filter plate 78 is fixedly installed inside the liquid storage tank 74. In this embodiment, the top of the filter plate 78 is flush with the top of the liquid storage tank 74.

[0051] A filter membrane 79 is laid on the top of the filter plate 78.

[0052] The storage tank 74 has an overflow port 68 on its side wall and a second discharge port 77 at its bottom, with the overflow port 68 located below the filter plate 78.

[0053] The overflow port 68 is connected to the third liquid inlet 66 located on the top of the buffer tank 63 via the twenty-fourth pipeline 67. When the liquid level in the storage tank 74 is unexpectedly too high, it can overflow into the buffer tank 63.

[0054] The top of the buffer tank 63 is also provided with an exhaust port 65, which is connected to the first vacuum unit 14 through the sixth pipeline 13. When the airflow enters the buffer tank 63 from the filter tank, preliminary gas-liquid separation can be achieved, and the liquid is temporarily stored in the buffer tank 63.

[0055] The buffer tank 63 is equipped with a first insulation layer 64.

[0056] The bottom of the buffer tank 63 is provided with a third discharge port.

[0057] The second discharge port 77 is connected to the crystallizer 7 via the fourth pipeline 8, and the second valve body 11 is installed on the fourth pipeline 8.

[0058] The third discharge port is connected to the fourth pipe 8 through the fifth pipe 10. The first valve body 9 is installed on the fifth pipe 10. The connection point between the fifth pipe 10 and the fourth pipe 8 is between the second valve body 11 and the crystallizing kettle 7.

[0059] A first liquid level sensor 75 is installed inside the liquid storage tank 74.

[0060] A second liquid level sensor is installed inside the buffer tank 63.

[0061] After the potassium nitrate in the dissolving tank 16 has completely dissolved, the first vacuum unit 14 and the corresponding third valve body are turned on, and the potassium nitrate solution enters the filter tank for filtration. When the first liquid level sensor 75 detects that the liquid level in the filter tank has reached the upper limit, the controller opens the second valve body 11 and adjusts its opening to keep the liquid level in the filter tank always above the set lower limit liquid level, so that the filtered potassium nitrate solution can seal the second outlet 77.

[0062] When the fourth liquid level sensor detects that the liquid level in the dissolving tank 16 is zero, the controller shuts down the first vacuum unit 14 and fully opens the second valve body 11 until the liquid level in the filter tank is zero, at which point the second valve body 11 is closed.

[0063] When the second liquid level sensor detects that the liquid level in the buffer tank 63 has reached the predetermined liquid level, the first valve body 9 is opened, allowing the liquid in the buffer tank 63 to enter the crystallizing kettle 7.

[0064] The structure of crystallization vessel 7 is shown in the attached figure. Figure 6 As shown, it includes a vessel body 81, and a second jacket 89 is fixedly installed on the outside of the vessel body 81. The upper part of the second jacket 89 is provided with a second liquid outlet 88, and the lower part is provided with a fourth liquid inlet 91.

[0065] The top of the vessel body 81 is provided with a manhole 82 and a second feed port 85, and a second end cap is hinged to the manhole 82.

[0066] A second base 83 is bolted to the middle of the top of the vessel body 81. A second motor 84 is bolted to the top of the second base 83. The output end of the second motor 84 is fixedly connected to the first end of the second stirring shaft 86 via a coupling. The second end of the second stirring shaft 86 is inserted into the vessel body 81 and a second stirring paddle 87 is installed thereon.

[0067] The bottom of the vessel body 81 is provided with a fourth discharge port 90.

[0068] A third liquid level sensor is installed inside the vessel body 81.

[0069] As attached Figure 1 As shown, the fourth liquid inlet 91 is connected to the refrigerant outlet of the cold source 6 through the third pipe 5, and the refrigerant inlet of the cold source 6 is connected to the second liquid outlet 88 through the second pipe 4.

[0070] The aforementioned fourth pipeline 8 is connected to the second feed inlet 85.

[0071] The fourth discharge port 90 is connected to the feed port of the centrifuge 41 through the first pipeline 3, and the first pump is installed on the first pipeline 3.

[0072] The liquid outlet of centrifuge 41 is connected to the inlet of hydrocyclone 23 via the twelfth pipe 22, and the outlet of hydrocyclone 23 is connected to the inlet of ceramic membrane filter 25 via the thirteenth pipe 24.

[0073] The solids separated by the hydrocyclone separator 23 are treated for redissolution.

[0074] The ceramic membrane filter 25 is connected in sequence to the cation resin column 33 and the first temporary storage tank 35 via the nineteenth pipeline 34.

[0075] After being processed by the hydrocyclone separator 23, the mother liquor is then processed sequentially through the ceramic membrane filter 25 and the cation exchange resin column 33 before entering the first temporary storage tank 35 for temporary storage.

[0076] The first temporary storage tank 35 is connected to the heat medium inlet in sequence through the fourteenth pipe 26 and the eleventh pipe 21, that is, the mother liquor separated by the centrifuge 41 is reused as a solvent.

[0077] On the eleventh pipeline 21, from the first temporary storage tank 35 to the heat source 20, the second pump, the second heat exchanger 30, and the first heat exchanger 27 are installed in sequence.

[0078] The solid discharge port of centrifuge 41 is connected to dryer 1 through the twenty-third pipe 42. Dryer 1 is heated by a steam jacket. The steam inlet of the steam jacket is connected to the heat source pipe 2. The steam outlet of the steam jacket is connected to the heat medium inlet of the first heat exchanger 27 through the twenty-first pipe 36. The heat medium outlet of the first heat exchanger 27 is connected to the liquid inlet of the second temporary storage tank 39 through the sixteenth pipe 29.

[0079] The outlet of the second temporary storage tank 39 is connected to the heat medium inlet of the heat source 20 via the twenty-first pipeline 38. The waste steam discharged from the dryer 1 enters the first heat exchanger 27 to heat the refluxed mother liquor, which can effectively reduce the energy consumption of the heat source 20. The condensate produced after the waste steam exchanges heat in the first heat exchanger 27 enters the second temporary storage tank 39 to replenish the heat medium, i.e., the solvent loss.

[0080] The exhaust outlet of dryer 1 is connected to the second vacuum unit 37 via the twenty-second pipe 40. The second vacuum unit 37 is connected to the heat medium inlet of the second heat exchanger 30 via the eighteenth pipe 32. The heat medium outlet of the second heat exchanger 30 is connected to the second temporary storage tank 39 via the seventeenth pipe 31. The vapor generated by potassium nitrate during the drying process is discharged from dryer 1 by the second vacuum unit 37 to maintain the negative pressure state of dryer 1. The vapor discharged by the second vacuum unit 37 enters the second heat exchanger 30 to heat the reflux mother liquor, which can effectively reduce the energy consumption of heat source 20.

[0081] The inlet of the heat medium in the second heat exchanger 30 is also connected to the exhaust pipe 46 via the fifteenth pipe 28. The steam generated during the dissolution of potassium nitrate can also be used to heat the reflux mother liquor.

[0082] It also includes a ninth pipe 18 connected to the heat medium inlet of the heat source 20, which is also connected to a pure water device for replenishing the heat medium.

[0083] In this embodiment, all three-way valves are electric three-way valves, and all valve bodies are electric flow valves.

[0084] The pipeline referred to in this embodiment includes not only pipes, but also corresponding valves, tees, etc. The configuration of these components is conventional technology in the field and will not be described in detail.

[0085] In this embodiment, all electrical components are controlled by a controller.

[0086] The operation process of this invention is as follows: The technical solution of this potassium nitrate purification device operates as follows: First, the heat source 20 is started. The heat medium heated by the heat source 20, i.e., the solvent for dissolving potassium nitrate, enters the coil 53 connected to the inlet pipe 50 through the tenth pipe 19. When the heat medium flows in the coil 53, it preheats the inside of the first tank 43. Then, the heat medium flows out from the second end of the outlet pipe 57, enters the inside of the first tank 43 through the connecting pipe 58 and the solvent inlet on the first tank 43. When the fourth liquid in the first tank 43... When the level sensor detects that the solvent has reached the predetermined level, the first three-way valve 59 is activated, causing the heat medium to be diverted through the seventh pipeline 15 into the first jacket 52, and then return to the heat source 20 from the first outlet 51 through the eighth pipeline 17 to form a cycle. At this time, potassium nitrate to be purified is added into the first tank 43 through the first feed port 44, and the first motor 47 is started. The first motor 47 drives the first stirring shaft 49 and the first stirring paddle located in the cylindrical space of the coil 53 to rotate, stirring the potassium nitrate and solvent until they are completely dissolved.

[0087] After dissolution, the third valve on the transfer pipe at the first outlet 55 is opened, and the potassium nitrate solution enters the filter device 12 through the transfer pipe. The solution enters the storage tank 74 from the first solution inlet 71 or the second solution inlet 72 of the filter tank in the filter device 12. It is filtered by the filter membrane 79 in the storage tank 74. At the same time, the first vacuum unit 14 is started to maintain a negative pressure environment to promote filtration. When the first liquid level sensor 75 in the storage tank 74 detects that the liquid level has reached the upper limit, the controller opens the second valve 11 and adjusts the opening, so that the filtered solution enters the body 81 of the crystallizing kettle 7 from the second outlet 77 through the fourth pipe 8. If the liquid level in the storage tank 74 is too high, the solution can flow back into the buffer tank 63 from the overflow port 68 through the twenty-fourth pipe 67. When the second liquid level sensor in the buffer tank 63 detects that the liquid level has reached the predetermined value, the first valve 9 is opened, so that the liquid in the buffer tank 63 flows into the fourth pipe 8 through the fifth pipe 10 and then enters the body 81 together.

[0088] After the solution enters the vessel 81, the refrigerant from the cold source 6 enters the second jacket 89 through the third pipe 5, and then returns to the cold source 6 from the second outlet 88 through the second pipe 4 to form a cycle, cooling the solution in the vessel 81. At the same time, the second motor 84 is started, which drives the second stirring shaft 86 and the second stirring paddle 87 to rotate and promote crystallization. The slurry formed is transported from the fourth outlet 90 through the first pipe 3 to the centrifuge 41.

[0089] The slurry undergoes solid-liquid separation in centrifuge 41. The separated solids enter dryer 1 through the 23rd pipe 42, while the separated liquid enters hydrocyclone 23 from the liquid outlet through the 12th pipe 22. The solids separated by hydrocyclone 23 are returned for redissolution, and the mother liquor enters ceramic membrane filter 25 through the 13th pipe 24, then flows through cation exchange resin column 33 through the 19th pipe 34 before entering first temporary storage tank 35 for temporary storage. The mother liquor in first temporary storage tank 35 is transported to the heat medium inlet of heat source 20 through the 11th pipe 21 for solvent reuse. The solids entering dryer 1 are dried by heating in a steam jacket. Steam enters the steam jacket from heat source pipe 2, and the waste steam generated during drying enters the first heat exchanger 27 from the steam outlet through the 20th pipe 36. The condensate formed after heating enters the second temporary storage tank 39 through the sixteenth pipe 29. The exhaust gas from the dryer 1 enters the second vacuum unit 37 through the twenty-second pipe 40, and then enters the second heat exchanger 30 through the eighteenth pipe 32. In the first heat exchanger 27 and the second heat exchanger 30, the waste steam and waste gas heat the reflux mother liquor in the eleventh pipe 21, respectively. Then, the medium discharged from the second heat exchanger 30 enters the second temporary storage tank 39 through the seventeenth pipe 31. The condensate in the second temporary storage tank 39 is transported to the heat medium inlet of the heat source 20 through the twenty-first pipe 38 to replenish the heat medium loss. At the same time, new heat medium can be added to the heat source 20 through the ninth pipe 18, thus completing the entire purification process of potassium nitrate and realizing the reuse of mother liquor and efficient utilization of energy.

[0090] In the dissolution process, the dual heating and precise temperature control design of the dissolution tank 16 improves the dissolution effect of potassium nitrate: the coil 53 installed inside the tank via the bracket 54 and the first jacket 52 outside form a dual heating structure with the inner coil 53 preheating and the outer jacket insulation. The heat medium, i.e. the solvent used for dissolution, first flows through the coil 53 to uniformly preheat the inside of the first tank 43. Then, the flow direction can be switched through the first three-way valve 59, so that it can either enter the tank directly as a solvent to participate in dissolution, or enter the first jacket 52 to form a circulation insulation. At the same time, the first stirring paddle driven by the first motor 47 is located in the cylindrical space formed by the coil 53. During the stirring process, it can fully contact the potassium nitrate and the solvent. With the gap fit between the coil 53 and the inner wall of the first tank 43, it not only avoids the problem of local overheating or insufficient dissolution, but also ensures that the potassium nitrate dissolves quickly and uniformly. It also realizes the recycling of the heat medium and reduces the initial loss of solvent and heat energy. In addition, the temperature sensor, fourth liquid level sensor and sampling port installed on the top of the dissolving tank 16 can monitor the dissolving status in real time, further ensuring the stability and controllability of the dissolving process. The exhaust pipe 46 installed on the top of the dissolving tank 16 can discharge the gas in the tank in a timely manner and maintain the stable pressure inside the tank.

[0091] In the filtration stage, the negative pressure drive and anti-overflow design of the filtration device 12 effectively ensure filtration efficiency and solution stability: the storage tank 74 of the filtration device 12 is equipped with a filter plate 78 and a filter membrane 79, which can efficiently intercept solid impurities in the potassium nitrate solution. Combined with the negative pressure environment created by the first vacuum unit 14 through the buffer tank 63, the filtration rate of the solution is greatly accelerated. The overflow port 68 on the side wall of the storage tank 74 is connected to the third inlet 66 of the buffer tank 63 through the twenty-fourth pipeline 67. When the liquid level in the storage tank 74 is accidentally too high, the solution can flow back to the buffer tank 63 for temporary storage, avoiding the waste of raw materials caused by solution overflow. At the same time, the second insulation layer 76 of the storage tank 74 and the first insulation layer 64 of the buffer tank 63 can maintain the solution temperature and prevent the solution from crystallizing prematurely due to temperature drop during the filtration process, thereby avoiding the blockage of the filter membrane 79 by crystal particles and affecting the filtration effect. In addition, the first liquid level sensor 75 in the filter tank and the second liquid level sensor in the buffer tank 63 can monitor the liquid level in real time to ensure the continuous and stable filtration process.

[0092] In the crystallization and separation process, the uniform cooling of the crystallization vessel 7 and the multi-stage purification design of the mother liquor respectively improve the crystallization purity and resource utilization rate: the second jacket 89 outside the crystallization vessel 7 is circulated with the cold source 6 to form a cooling cycle. The fourth liquid inlet 91 at the bottom of the second jacket 89 is connected to the refrigerant outlet of the cold source 6 through the third pipe 5, and the second liquid outlet 88 at the top is connected to the refrigerant inlet of the cold source 6 through the second pipe 4. Combined with the second stirring shaft 86 and the second stirring paddle 87 driven by the second motor 84, the solution is continuously stirred, ensuring uniform cooling of the solution and preventing... This process addresses the issue of uneven crystallization or impurities caused by localized overcooling, improving the purity and particle consistency of potassium nitrate crystals. The mother liquor separated by centrifuge 41 is not directly discharged but undergoes multi-stage purification via hydrocyclone separator 23, ceramic membrane filter 25, and cation exchange resin column 33. The purified mother liquor is then temporarily stored in the first temporary storage tank 35 and reused as a solvent in heat source 20. This reduces solvent consumption and avoids the impact of impurity accumulation on potassium nitrate purity during reuse through the step-by-step removal of impurities, thus achieving resource recycling.

[0093] In the drying and energy utilization stage, the waste heat recovery and heat medium replenishment design of dryer 1 significantly reduces the overall energy consumption: dryer 1 adopts steam jacket heating, and its discharged waste steam enters the first heat exchanger 27 through the twentieth pipe 36 to preheat the reflux mother liquor. The condensate formed after heat exchange enters the second temporary storage tank 39 through the sixteenth pipe 29; at the same time, the exhaust gas of dryer 1 enters the second vacuum unit 37 through the twenty-second pipe 40, and then enters the second heat exchanger 30 through the eighteenth pipe 32, similarly preheating the reflux mother liquor in the eleventh pipe 21. Heating the liquid maintains the negative pressure environment inside the dryer 1 to improve drying efficiency and also enables the recovery and utilization of waste heat in the exhaust gas. The media after heat exchange at both locations eventually flow into the second temporary storage tank 39. The condensate in the tank can be supplemented to the heat source 20 as a heat medium through the twenty-first pipeline 38. The pure water device connected through the ninth pipeline 18 replenishes the new heat medium, effectively compensating for the loss of heat medium during the circulation process. Through the cascade heat exchange between waste steam and waste gas, the energy demand of the heat source 20 is reduced, the overall energy consumption is lowered, and the efficient utilization of energy is achieved.

[0094] In addition, all pipelines in the device are connected by flanges, all valves are electric flow valves, and all electrical components are controlled by a controller. This not only ensures the sealing and stability of the entire process, but also improves the convenience and automation of operation, making it easy for large-scale industrial applications. Overall, it provides a highly efficient, environmentally friendly, economical and stable technical solution for potassium nitrate purification.

[0095] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A potassium nitrate purification device, characterized in that: The system includes a dissolving tank (16), a filter (12), a crystallizing vessel (7), a centrifuge (41), and a dryer (1) heated by a steam jacket, which are connected in series via pipelines. The dissolving tank (16) includes a first tank body (43) with a first jacket (52) on it. The first jacket (52) is connected to a heat source (20) via a circulation pipeline. The liquid outlet of the centrifuge (41) is connected in sequence via pipelines to a hydrocyclone separator (23), a ceramic membrane filter (25), a cation exchange resin column (33), a first temporary storage tank (35), and the heat medium inlet of the heat source (20). A second heat exchanger (30) and a first heat exchanger are installed in sequence on the pipeline between the first temporary storage tank (35) and the heat medium inlet. The steam outlet of the steam jacket is connected to the heat medium inlet of the first heat exchanger (27) through the twentieth pipe (36). The heat medium outlet of the first heat exchanger (27) is connected to the liquid inlet of the second temporary storage tank (39) through the sixteenth pipe (29). The liquid outlet of the second temporary storage tank (39) is connected to the heat medium inlet through the twenty-first pipe (38). The exhaust gas outlet of the dryer (1) is connected to the second vacuum unit (37) through the twenty-second pipe (40). The second vacuum unit (37) is connected to the heat medium inlet of the second heat exchanger (30) through the eighteenth pipe (32). The heat medium outlet of the second heat exchanger (30) is connected to the liquid inlet of the second temporary storage tank (39) through the seventeenth pipe (31).

2. The potassium nitrate purification apparatus according to claim 1, characterized in that: The first tank (43) is equipped with a coil (53) inside by a bracket (54). The bottom of the coil (53) is fixedly connected to the first end of the inlet pipe (50). The second end of the inlet pipe (50) passes through the top of the first tank (43) and is connected to the heat medium outlet of the heat source (20) through the tenth pipe (19). The top of the coil (53) is fixedly connected to the first end of the outlet pipe (57). The second end of the outlet pipe (57) passes through the first tank (43) and is connected to the solvent inlet on the first tank (43) through a connecting pipe (58). A first three-way valve (59) is installed on the connecting pipe (58). The first three-way valve (59) is connected to the first inlet (56) of the first jacket (52) through the seventh pipe (15). The first outlet (51) of the first jacket (52) is connected to the heat medium inlet of the heat source (20) through the eighth pipe (17).

3. The potassium nitrate purification apparatus according to claim 2, characterized in that: The first tank (43) is equipped with a first stirring shaft (49) driven by a first motor (47), and a first stirring paddle is fixedly installed on the first stirring shaft (49).

4. The potassium nitrate purification apparatus according to claim 3, characterized in that: An exhaust pipe (46) is installed on the top of the first tank (43).

5. The potassium nitrate purification apparatus according to claim 4, characterized in that: The first stirring paddle is located in the cylindrical space formed by the coil (53).

6. The potassium nitrate purification apparatus according to claim 2, characterized in that: The filtration device (12) includes a filter tank. The inlet of the filter tank is connected to the dissolving tank (16) through a flow pipe with a third valve body installed. An overflow port (68) is provided on the side wall of the filter tank. The overflow port (68) is connected to the third inlet port (66) at the top of the buffer tank (63) through the twenty-fourth pipe (67). The exhaust port (65) at the top of the buffer tank (63) is connected to the first vacuum unit (14) through the sixth pipe (13). The bottom of the filter tank is connected to the crystallizer (7) through the fourth pipe (8). A second valve body (11) is installed on the fourth pipe (8). The third outlet at the bottom of the buffer tank (63) is connected to the fourth pipe (8) through the fifth pipe (10). A first valve body (9) is installed on the fifth pipe (10). The connection point between the fifth pipe (10) and the fourth pipe (8) is between the second valve body (11) and the crystallizer (7).

7. The potassium nitrate purification apparatus according to claim 6, characterized in that: The filter tank includes a liquid storage tank (74), the top of which is detachably covered with a top cover (70). A disc-shaped filter plate (78) is fixedly installed inside the liquid storage tank (74), and a filter membrane (79) is laid on the top of the filter plate (78). The overflow port (68) is located below the filter plate (78).

8. The potassium nitrate purification apparatus according to claim 7, characterized in that: The liquid storage tank (74) is equipped with a second insulation layer (76), and the buffer tank (63) is equipped with a first insulation layer (64).

9. The potassium nitrate purification apparatus according to claim 8, characterized in that: The crystallizing vessel (7) is equipped with a second jacket (89). The upper part of the second jacket (89) is provided with a second liquid outlet (88), and the lower part is provided with a fourth liquid inlet (91). The fourth liquid inlet (91) is connected to the refrigerant outlet of the cold source (6) through a third pipeline (5). The refrigerant inlet of the cold source (6) is connected to the second liquid outlet (88) through a second pipeline (4).

10. The potassium nitrate purification apparatus according to claim 9, characterized in that: The dissolving tank (16) is equipped with a fourth liquid level sensor, the crystallizing vessel (7) is equipped with a third liquid level sensor, the filter tank is equipped with a first liquid level sensor (75), and the buffer tank (63) is equipped with a second liquid level sensor; the second liquid level sensor, the first liquid level sensor (75), the third liquid level sensor, and the fourth liquid level sensor are all electrically connected to the controller.

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