Potassium nitrate purification device

Abstract

The invention relates to the technical field of nitrate production, in particular to a potassium nitrate purification device which comprises a dissolving tank, a filtering device, a crystallization kettle, a centrifugal machine and a drying machine with a steam jacket which are sequentially connected in series through pipelines. The dissolving tank first jacket is connected with a heat source through a circulating pipeline; a liquid outlet of the centrifugal machine is sequentially connected with the cyclone separator, the ceramic membrane filter, the cationic resin column, the first temporary storage tank and the heat source, and the first heat exchanger and the second heat exchanger are sequentially installed between the first temporary storage tank and a heating medium inlet of the heat source. A steam outlet pipeline of the steam jacket is connected with a heat medium inlet of the first heat exchanger, the first heat exchanger is connected with the second temporary storage tank through a pipeline, and the second temporary storage tank is connected with the heat source through a pipeline. A pipeline of the second vacuum unit is connected with a thermal medium inlet of a second heat exchanger, and the second heat exchanger is connected with a second temporary storage tank. According to the method, the potassium nitrate purification efficiency, the product purity, the resource utilization rate and the energy economy are synergistically improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nitrate production, in particular to a potassium nitrate purification device. BACKGROUND

[0002] As an important inorganic chemical raw material, potassium nitrate is widely used in the fields of agriculture, industry, food processing and medicine, and the purity of the product directly determines the quality and effect of downstream applications, so the industrial purification technology is one of the core links of the development of the potassium nitrate industry. At present, the mainstream potassium nitrate purification process in the industry has defects in the integration degree of the process and the refinement degree of the core equipment design, which leads to the prominent contradiction between the efficiency, purity, resource utilization and energy consumption in the purification process, and it is difficult to meet the needs of industrial production for high efficiency, high purity and low energy consumption. SUMMARY

[0003] In order to solve the defects in the prior art, the application provides a potassium nitrate purification device, which is realized by the following technical scheme: A potassium nitrate purification device, comprising a dissolving tank, a filtering device, a crystallization kettle, a centrifuge and a drying machine heated by a steam jacket connected in series through pipelines, the dissolving tank comprises a first tank body, a first jacket is arranged on the first tank body, the first jacket is connected with a heat source through a circulating pipeline, the liquid outlet of the centrifuge is connected with a cyclone separator, a ceramic membrane filter, a cation resin column, a first temporary storage tank and a heat medium inlet of the heat source in sequence through pipelines, a second heat exchanger and a first heat exchanger are installed on the pipeline between the first temporary storage tank and the heat medium inlet in sequence, the steam outlet of the steam jacket is connected with the heat medium inlet of the first heat exchanger through the twentieth pipeline, the heat medium outlet of the first heat exchanger is connected with the liquid inlet of the second temporary storage tank through the sixteenth pipeline, the liquid outlet of the second temporary storage tank is connected with the heat medium inlet through the twenty-first pipeline, the waste gas outlet of the drying machine is connected with a second vacuum unit through the twenty-second pipeline, the second vacuum unit is connected with the heat medium inlet of the second heat exchanger through the eighteenth pipeline, and the heat medium outlet of the second heat exchanger is connected with the liquid inlet of the second temporary storage tank through the seventeenth pipeline.

[0004] The inside of the first tank body is provided with a coil pipe mounted through a support, the bottom of the coil pipe is fixedly connected with the first end of a liquid inlet pipe, the second end of the liquid inlet pipe penetrates out of the top of the first tank body and is connected with the heat medium outlet of the heat source through the tenth pipeline, the top of the coil pipe is fixedly connected with the first end of a liquid outlet pipe, the second end of the liquid outlet pipe penetrates out of the first tank body and is connected with the solvent inlet on the first tank body through a connecting pipe, a first three-way valve is installed on the connecting pipe, the first three-way valve is connected with the first liquid inlet of the first jacket through the seventh pipeline, and the first liquid outlet of the first jacket is connected with the heat medium inlet of the heat source through the eighth pipeline.

[0005] The first tank body is provided with a first stirring shaft driven by a first motor, and the first stirring shaft is fixedly provided with a first stirring paddle.

[0006] The first tank body is provided with an exhaust pipe at the top.

[0007] The first stirring paddle is located in a cylindrical space formed by a coil pipe.

[0008] The filter device comprises a filter tank, a liquid inlet of the filter tank is connected with the dissolving tank through a flow pipe provided with a third valve body, a side wall of the filter tank is provided with an overflow port, the overflow port is connected with a third liquid inlet provided at the top of a buffer tank through a twenty-fourth pipeline, an exhaust port at the top of the buffer tank is connected with a first vacuum unit through a sixth pipeline, the bottom of the filter tank is connected with a crystallization kettle through a fourth pipeline, the fourth pipeline is provided with a second valve body, a third discharge port at the bottom of the buffer tank is connected with the fourth pipeline through a fifth pipeline, the fifth pipeline is provided with a first valve body, and a connection point of the fifth pipeline and the fourth pipeline is between the second valve body and the crystallization kettle.

[0009] The filter tank comprises a liquid storage groove, the top of the liquid storage groove is detachably provided with an upper cover, a disc-shaped filter plate is fixedly arranged in the liquid storage groove, a filter membrane is arranged on the top of the filter plate, and the overflow port is located below the filter plate.

[0010] The liquid storage groove is provided with a second heat preservation layer, and the buffer tank is provided with a first heat preservation layer.

[0011] The crystallization kettle is provided with a second jacket, a second liquid outlet is arranged at the upper portion of the second jacket, and a fourth liquid inlet is arranged at the lower portion of the second jacket, the fourth liquid inlet is connected with a refrigerant outlet of a cold source through a third pipeline, and a refrigerant inlet of the cold source is connected with the second liquid outlet through a second pipeline.

[0012] A fourth liquid level sensor is arranged in the dissolving tank, a third liquid level sensor is arranged in the crystallization kettle, a first liquid level sensor is arranged in the filter tank, and a second liquid level sensor is arranged in the buffer tank, and the second liquid level sensor, the first liquid level sensor, the third liquid level sensor and the fourth liquid level sensor are electrically connected with a controller.

[0013] The technical scheme has the following advantages: The potassium nitrate purification device of the present application realizes the synergistic improvement of the potassium nitrate purification efficiency, product purity, resource utilization rate and energy economy by constructing an integrated process of dissolution, filtration, crystallization, separation, drying and reuse, and combining the fine structure design of each core equipment, effectively solves the technical defects such as uneven dissolution, low filtration efficiency, serious mother liquor waste and high energy consumption which exist in the existing potassium nitrate purification technology, and provides an efficient and environmentally friendly technical scheme for the industrialized purification of potassium nitrate. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0015] Figure 1 is a structural schematic diagram of the present application; Figure 2 is a structural schematic diagram of the dissolution tank; Figure 3 is a structural schematic diagram of the top of the dissolution tank; Figure 4 is a structural schematic diagram of the filtration device; Figure 5 is a structural schematic diagram of the filter element; Figure 4 is a structural schematic diagram of A in the middle; Figure 6 is a structural schematic diagram of the kettle body.

[0016] In the figure, 1-dryer, 2-heat source pipe, 3-first pipe, 4-second pipe, 5-third pipe, 6-cold source, 7-crystallization kettle, 8-fourth pipe, 9-first valve body, 10-fifth pipe, 11-second valve body, 12-filtering device, 13-sixth pipe, 14-first vacuum unit, 15-seventh pipe, 16-dissolution 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 temporary storage tank, 36-twentieth pipe, 37-second vacuum unit, 38-twenty-first pipe, 39-second temporary storage tank, 40-twenty-second pipe, 41-centrifuge, 42-twenty-third pipe, 43-first tank body, 44-first feed inlet, 45-first end cover, 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 pipe, 54-bracket, 55-first discharge outlet, 56-first liquid inlet, 57-liquid outlet pipe, 58-connection pipe, 59-first three-way valve, 60-connection block, 61-second liquid inlet, 62-mounting interface, 63-buffer tank, 64-first heat preservation layer, 65-exhaust port, 66-third liquid inlet, 67-twenty-fourth pipe, 68-overflow port, 69-first storage tank flange, 70-upper cover, 71-first solution inlet, 72-second solution inlet, 73-second storage tank flange, 74-liquid storage groove, 75-first liquid level sensor, 76-second heat preservation layer, 77-second discharge outlet, 78-filter plate, 79-filter membrane, 80-sealing ring, 81-kettle 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 outlet, 91-fourth liquid inlet. DETAILED DESCRIPTION

[0017] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0018] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the modules or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0020] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0021] In this embodiment, the connection between the pipelines, the connection between the pipelines and the corresponding equipment, the connection between the interfaces and the valves, etc. are all realized by flanges unless otherwise specified.

[0022] As shown in the accompanying Figure 1 The present application provides a potassium nitrate purification device, which comprises a dissolving tank 16, a filtering device 12, a crystallization kettle 7, a centrifuge 41 and a drying machine 1 connected in series through pipelines; the potassium nitrate to be purified is heated and redissolved in the dissolving tank 16, the potassium nitrate solution is filtered into the filtering device 12, then the potassium nitrate solution is cooled and recrystallized in the crystallization kettle 7, then the slurry is separated into solid and liquid in the centrifuge 41, the solid is dried in the drying machine 1, and the mother liquor is recycled.

[0023] The structure of the dissolving tank 16 is shown in the accompanying Figure 2 and the accompanying Figure 3 It comprises a first tank body 43, a first jacket 52 is fixedly installed at the lower part of the first tank body 43, a first liquid outlet 51 is arranged at the upper part of the first jacket 52, and a first liquid inlet 56 is arranged at the lower part of the first jacket 52, and the first jacket 52 is used for passing heat medium to heat and insulate the inside of the first tank body 43.

[0024] A first discharge port 55 is arranged at the bottom of the first tank body 43.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The coil 53 is fitted with the inner wall of the first tank 43 with a clearance fit.

[0031] 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.

[0032] The first end of the exhaust pipe 46 is connected to the corresponding mounting interface 62 via a flange.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Add the potassium nitrate to be dissolved into the first tank 43, start the first motor 47, and stir until fully dissolved.

[0040] 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.

[0041] A sealing ring 80 is installed between the second storage tank flange 73 and the first storage tank flange 69.

[0042] 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.

[0043] 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.

[0044] A filter membrane 79 is laid on the top of the filter plate 78.

[0045] 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.

[0046] The overflow port 68 is connected with the third liquid inlet 66 arranged at the top of the buffer tank 63 through the twenty-fourth pipeline 67, and when the liquid level in the storage tank 74 is unexpectedly high, the overflow can be discharged into the buffer tank 63.

[0047] The top of the buffer tank 63 is also provided with an exhaust port 65 connected with the first vacuum set 14 through the sixth pipeline 13. When the gas flow enters the buffer tank 63 from the filter tank, the preliminary gas-liquid separation can be realized, and the liquid is temporarily stored in the buffer tank 63.

[0048] The first heat preservation layer 64 is installed on the buffer tank 63.

[0049] The third discharge port is arranged at the bottom of the buffer tank 63.

[0050] The second discharge port 77 is connected with the crystallization kettle 7 through the fourth pipeline 8, and the second valve body 11 is installed on the fourth pipeline 8.

[0051] The third discharge port is connected with the fourth pipeline 8 through the fifth pipeline 10, and the first valve body 9 is installed on the fifth pipeline 10. The connection point of the fifth pipeline 10 and the fourth pipeline 8 is between the second valve body 11 and the crystallization kettle 7.

[0052] The first liquid level sensor 75 is installed in the storage tank 74.

[0053] The second liquid level sensor is installed in the buffer tank 63.

[0054] When the potassium nitrate solution in the dissolving tank 16 is dissolved, the first vacuum set 14 and the corresponding third valve body are opened, the potassium nitrate solution enters the filter tank for filtration, and when the first liquid level sensor 75 detects that the liquid level in the filter tank reaches the upper limit, the controller opens the second valve body 11 and adjusts the opening degree, so that the liquid level in the filter tank is always kept above the set lower limit, and the filtered potassium nitrate solution can seal the second discharge port 77.

[0055] When the fourth liquid level sensor detects that the liquid level of the dissolving tank 16 is zero, the controller closes the first vacuum set 14, and completely opens the second valve body 11 until the liquid level in the filter tank is zero, and then closes the second valve body 11.

[0056] When the second liquid level sensor detects that the liquid level in the buffer tank 63 reaches the predetermined liquid level, the first valve body 9 is opened, so that the liquid in the buffer tank 63 enters the crystallization kettle 7.

[0057] The structure of the crystallization kettle 7 is shown in the attached Figure 6 The structure of the crystallization kettle 7 is shown in the attached

[0058] 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.

[0059] 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.

[0060] The bottom of the vessel body 81 is provided with a fourth discharge port 90.

[0061] A third liquid level sensor is installed inside the vessel body 81.

[0062] 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.

[0063] The aforementioned fourth pipeline 8 is connected to the second feed inlet 85.

[0064] 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.

[0065] 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.

[0066] The solids separated by the hydrocyclone separator 23 are treated for redissolution.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] The solid outlet of the centrifuge 41 is connected with the drying machine 1 through the twenty-third pipeline 42. The drying machine 1 is heated by a steam jacket. The steam inlet of the steam jacket is connected with the heat source pipeline 2. The steam outlet of the steam jacket is connected with the heat medium inlet of the first heat exchanger 27 through the twentieth pipeline 36. The heat medium outlet of the first heat exchanger 27 is connected with the liquid inlet of the second temporary storage tank 39 through the sixteenth pipeline 29.

[0072] The liquid outlet of the second temporary storage tank 39 is connected with the heat medium inlet of the heat source 20 through the twenty-first pipeline 38. The waste steam discharged from the drying machine 1 is used to heat the refluxed mother liquor in the first heat exchanger 27, which can effectively reduce the energy consumption of the heat source 20. The condensed water produced in the first heat exchanger 27 is used to supplement the loss of the heat medium, i.e. the solvent.

[0073] The waste gas outlet of the drying machine 1 is connected with the second vacuum unit 37 through the twenty-second pipeline 40. The second vacuum unit 37 is connected with the heat medium inlet of the second heat exchanger 30 through the eighteenth pipeline 32. The heat medium outlet of the second heat exchanger 30 is connected with the second temporary storage tank 39 through the seventeenth pipeline 31. The steam produced in the drying process of potassium nitrate is discharged from the drying machine 1 by the second vacuum unit 37 to maintain the negative pressure state of the drying machine 1. The steam discharged by the second vacuum unit 37 is used to heat the refluxed mother liquor in the second heat exchanger 30, which can effectively reduce the energy consumption of the heat source 20.

[0074] The heat medium inlet of the second heat exchanger 30 is also connected with the exhaust pipe 46 through the fifteenth pipeline 28. The steam produced in the dissolution process of potassium nitrate can also be used to heat the refluxed mother liquor.

[0075] The ninth pipeline 18 connected with the heat medium inlet of the heat source 20 is also connected with a pure water device to supplement the heat medium.

[0076] All the three-way valves in the embodiment are electric three-way valves. All the valve bodies are electric flow valves.

[0077] The pipelines in the embodiment include pipelines and corresponding valves, three-way valves, etc. The arrangement of these components is a routine technique in the art, which will not be described in detail.

[0078] All the electric components in the embodiment are controlled by a controller.

[0079] The operation process of the present application is as follows: the technical scheme of the potassium nitrate purification device operates as follows: first, start the heat source 20, the heat medium heated by the heat source 20, that is, the solvent for dissolving potassium nitrate, enters the coil 53 connected with the liquid inlet pipe 50 through the tenth pipe 19, and the heat medium flows in the coil 53 to preheat the inside of the first tank body 43, then the heat medium flows out from the second end of the liquid outlet pipe 57, enters the first tank body 43 through the connecting pipe 58 and the solvent inlet on the first tank body 43, when the fourth liquid level sensor in the first tank body 43 detects that the solvent reaches the predetermined liquid level, the first three-way valve 59 acts, so that the heat medium changes its path through the seventh pipe 15 into the first jacket 52, and then returns to the heat source 20 through the eighth pipe 17 to form a circulation, at this time, the potassium nitrate to be purified is put into the first tank body 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 in the cylindrical space of the coil 53 to rotate, and the potassium nitrate and the solvent are stirred until completely dissolved.

[0080] After the dissolution is completed, the third valve body on the flow pipe at the first discharge port 55 is opened, the potassium nitrate solution enters the filter device 12 through the flow pipe, the solution enters the liquid storage tank 74 through the first solution inlet 71 or the second solution inlet 72 of the filter device 12, and is filtered through the filter membrane 79 in the liquid storage tank 74, and 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 liquid storage tank 74 detects that the liquid level reaches the upper limit, the controller opens the second valve body 11 and adjusts the opening degree, so that the filtered solution enters the kettle body 81 of the crystallization kettle 7 through the fourth pipe 8 from the second discharge port 77, if the liquid level in the liquid storage tank 74 is too high, the solution can flow back into the buffer tank 63 through the twenty-fourth pipe 67 from the overflow port 68, when the second liquid level sensor in the buffer tank 63 detects that the liquid level reaches a predetermined value, the first valve body 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 kettle body 81.

[0081] After the solution enters the kettle body 81, the coolant of the cold source 6 enters the second jacket 89 through the third pipe 5, and then returns to the cold source 6 through the second pipe 4 from the second liquid outlet 88 to form a circulation, and at the same time, the second motor 84 is started, the second motor 84 drives the second stirring shaft 86 and the second stirring paddle 87 to rotate to promote crystallization, and the formed slurry is transported to the centrifugal machine 41 through the first pipe 3 from the fourth discharge port 90.

[0082] The slurry is subjected to solid-liquid separation in the centrifuge 41, the separated solids enter the dryer 1 through the twenty-third pipeline 42, and the separated liquid enters the cyclone separator 23 from the liquid outlet through the twelfth pipeline 22, the solids separated by the cyclone separator 23 are returned for re-dissolution, the mother liquor enters the ceramic membrane filter 25 through the thirteenth pipeline 24, then flows through the cation resin column 33 through the nineteenth pipeline 34 and enters the first temporary storage tank 35 for temporary storage, and the mother liquor in the first temporary storage tank 35 is transported to the heat medium inlet of the heat source 20 through the eleventh pipeline 21 as a solvent for reuse; the solids entering the dryer 1 are dried by heating with a steam jacket, the steam enters the steam jacket from the heat source pipe 2, the waste steam generated by drying enters the first heat exchanger 27 from the steam outlet through the twentieth pipeline 36, the condensed water formed after heat exchange enters the second temporary storage tank 39 through the sixteenth pipeline 29, and the exhaust gas of the dryer 1 enters the second vacuum unit 37 through the twenty-second pipeline 40, and then enters the second heat exchanger 30 through the eighteenth pipeline 32; in the first heat exchanger 27 and the second heat exchanger 30, the waste steam and the exhaust gas heat the refluxed mother liquor in the eleventh pipeline 21, respectively, and then the medium discharged from the second heat exchanger 30 enters the second temporary storage tank 39 through the seventeenth pipeline 31, the condensed water in the second temporary storage tank 39 is transported to the heat medium inlet of the heat source 20 through the twenty-first pipeline 38 to supplement the heat medium loss, and at the same time, new heat medium can be supplemented to the heat source 20 through the ninth pipeline 18, thereby completing the entire purification process of potassium nitrate and realizing the reuse of the mother liquor and the efficient use of energy.

[0083] In the dissolution link, the double heating and precise temperature control design of the dissolution tank 16 improves the dissolution effect of potassium nitrate: the inner pipe 53 and the outer jacket 52 form a double heating structure of preheating the inner pipe 53 and heat preservation of the outer jacket, the heat medium, i.e. the solvent used for dissolution, first flows through the inner pipe 53 to uniformly preheat the inside of the first tank body 43, and then can be switched to flow direction by the first three-way valve 59, so as to enter the tank directly as a solvent for dissolution or enter the first jacket 52 to form a circulating heat preservation; at the same time, the first stirring paddle driven by the first motor 47 is located in the cylindrical space formed by the inner pipe 53, which can fully contact the potassium nitrate and the solvent during stirring, and cooperates with the gap between the inner pipe 53 and the inner wall of the first tank body 43 to not only avoid the problems of local overheating or insufficient dissolution, but also ensure the rapid and uniform dissolution of potassium nitrate; and the circulation of the heat medium is realized, thereby reducing the initial loss of the solvent and heat energy. In addition, the temperature sensor, the fourth liquid level sensor and the sampling port arranged at the top of the dissolution tank 16 can monitor the dissolution state in real time, thereby further ensuring the stability and controllability of the dissolution process, and the exhaust pipe 46 arranged at the top of the dissolution tank 16 can timely exhaust the gas in the tank to maintain the stability of the pressure in the tank.

[0084] In the filtering link, the negative pressure driving and the anti-overflow design of the filtering device 12 effectively guarantee the filtering efficiency and the solution stability: the filter plate 78 and the filter membrane 79 are arranged in the liquid storage tank 74 of the filtering device 12, can efficiently intercept the solid impurities in the potassium nitrate solution, and cooperate with the negative pressure environment formed by the buffer tank 63 through the first vacuum unit 14 to greatly accelerate the filtering rate of the solution; the overflow port 68 of the side wall of the liquid storage tank 74 is connected with the third liquid inlet 66 of the buffer tank 63 through the twenty-fourth pipeline 67, when the liquid level in the liquid storage tank 74 is unexpectedly too high, the solution can flow back to the buffer tank 63 for temporary storage, so as to avoid the waste of raw materials caused by solution overflow; meanwhile, the second heat preservation layer 76 of the liquid storage tank 74 and the first heat preservation layer 64 of the buffer tank 63 can maintain the solution temperature, prevent the solution from crystallizing in advance due to temperature drop in the filtering process, and then avoid the crystalline particles from blocking the filter membrane 79 and affecting the filtering effect, and the first liquid level sensor 75 in the filtering tank and the second liquid level sensor in the buffer tank 63 can monitor the liquid level in real time, so as to ensure the continuous stability of the filtering process.

[0085] In the crystallization and separation link, the uniform cooling of the crystallization kettle 7 and the multi-stage purification design of the mother liquor respectively improve the crystallization purity and the resource utilization rate: the second jacket 89 outside the crystallization kettle 7 is connected with the cold source 6 to form a circulating cooling, the fourth liquid inlet 91 at the lower part of the second jacket 89 is connected with the coolant outlet of the cold source 6 through the third pipeline 5, the second liquid outlet 88 at the upper part is connected with the coolant inlet of the cold source 6 through the second pipeline 4, and the second stirring shaft 86 and the second stirring paddle 87 driven by the second motor 84 continuously stir the solution, so that the whole solution is uniformly cooled, the problems of uneven crystalline particles or impurities caused by local supercooling are avoided, and the purity and the particle consistency of the potassium nitrate crystallization are improved; the mother liquor separated by the centrifugal machine 41 is not directly discharged, but is sequentially subjected to multi-stage purification through the cyclone separator 23, the ceramic membrane filter 25 and the cation resin column 33, the purified mother liquor is temporarily stored in the first temporary storage tank 35 and is reused to the heat source 20 as a dissolving solvent, which not only reduces the consumption of the solvent, but also avoids the influence of impurity accumulation on the purity of potassium nitrate in the reuse process through the step-by-step removal of impurities, so as to realize the recycling of resources.

[0086] In the drying and energy utilization link, the waste heat recovery and heat medium supplement design of the dryer 1 greatly reduces the overall energy consumption: the dryer 1 uses steam jacket heating, the exhaust steam thereof enters the twentieth pipeline 36 into the first heat exchanger 27 to preheat the reflux mother liquor, the condensed water formed after heat exchange enters the sixteenth pipeline 29 into the second temporary storage tank 39; at the same time, the exhaust gas of the dryer 1 enters the second vacuum unit 37 through the twenty-second pipeline 40, and then is introduced into the second heat exchanger 30 through the eighteenth pipeline 32, and similarly heats the reflux mother liquor in the eleventh pipeline 21, which not only maintains the negative pressure environment inside the dryer 1 to improve the drying efficiency, but also realizes the recycling of the waste heat in the exhaust gas; the media after heat exchange in two places finally converge into the second temporary storage tank 39, and the condensed water 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 supplements new heat medium, which effectively makes up for the loss of the heat medium in the circulation process; through the cascade heat exchange of the exhaust steam and the exhaust gas, the demand of the heat source 20 for energy is reduced, the overall energy consumption is reduced, and the efficient use of energy is realized.

[0087] In addition, all pipelines in the device are connected by flanges, each valve body is an electric flow valve, and all electrical components are linked and controlled by the controller, which not only ensures the sealing and stability of the whole process operation, but also improves the convenience and automation degree of operation, facilitates large-scale industrial application, and provides an efficient, environmentally friendly, economic and stable technical scheme for the purification of potassium nitrate as a whole.

[0088] Obviously, the above embodiments are only examples for clearly illustrating, and not limit the embodiments. For those skilled in the art, based on the above description, other different forms of changes or variations can also be made. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

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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