Spiral-flow type crystallization device

Abstract

The invention relates to the field of evaporative crystallization, in particular to a spiral-flow type crystallization device which comprises a crystallizer, the crystallizer comprises a vertically-arranged separation tower, a transverse expansion pipe extending in the tangential direction of the separation tower is fixedly installed on one side of the separation tower, the end, away from the separation tower, of the transverse expansion pipe is a feeding end, and the end, connected with the separation tower, of the transverse expansion pipe is a discharging end. The transverse expanding pipe is in a cone shape with the diameter gradually expanding from the feeding end to the discharging end. Rotational flow power is generated in the mode that crystal mush is fed in the tangential direction of a separation tower of the crystallizer, and therefore the two purposes of providing a movement environment for crystal growth and conducting centrifugal separation on large-particle crystals are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of evaporation crystallization, in particular to a cyclone crystallization device. Background Art

[0002] The existing large-particle crystal production process in China is mostly an intermittent production method involving crystal growth, crystal extraction, crystal screening, and slurry return. This method suffers from low production efficiency, large return volumes, and a wide product particle size distribution. The intermittent jacketed crystallizer used in CN119499699A is equipped with an agitator assembly to ensure thorough mixing and uniformity of the material at each stage through stirring. The crystallizer used in CN101531382A is internally equipped with a draft tube, a cylindrical baffle, and an agitator, with the agitator extending vertically from the bottom of the crystallizer into the draft tube.

[0003] As can be seen from this, most existing crystallizers are equipped with a stirring device, which leads to a complex internal structure of the crystallizer and also has the problem of low production efficiency. In the prior art, there is no crystallization device that uses rotary flow centrifugal separation and crystal circulation cultivation technology to complete crystal cultivation and separation. Summary of the Invention

[0004] The purpose of the present invention is to provide a cyclonic crystallization device, which solves the technical problems of low production efficiency of existing large-particle crystals and complex internal structure of the crystallizer through cyclonic centrifugal separation and crystal circulation cultivation technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A cyclone crystallization device includes a crystallizer, the crystallizer includes a vertically arranged separation tower, and a transverse expansion tube extending along its tangential direction is provided on one side of the separation tower. The end of the transverse expansion tube away from the separation tower is a feed end, and the end connected to the separation tower is a discharge end. The transverse expansion tube is conical in shape, with the diameter gradually increasing from the feed end to the discharge end.

[0006] As a further improvement, it also includes a slurry circulation pipe, the feed end of the slurry circulation pipe is connected to one side of the separation tower, the discharge end of the slurry circulation pipe is connected to the feed end of the transverse expansion pipe, and the slurry circulation pipe is provided with a slurry circulation pump and a slurry circulation heater.

[0007] As a further improvement, it also includes a crystal circulation pipe, the feed end of the crystal circulation pipe is connected to one side of the separation tower, the outer wall of the transverse expansion pipe is provided with a plurality of crystal circulation addition inlets evenly spaced along its length direction, the plurality of crystal circulation addition inlets are respectively connected to the discharge ends of the crystal circulation pipe, and the crystal circulation pipe is provided with a crystal circulation pump.

[0008] As a further improvement, the feed end of the crystal circulation pipe is lower than the feed end of the slurry circulation pipe.

[0009] As a further improvement, the upper end of the separation tower is connected to a vacuum control system.

[0010] As a further improvement, the separation tower is a hollow tower body, and the lower end of the separation tower is arranged in an inverted cone shape.

[0011] As a further improvement, the lower end of the separation tower is connected to the slurry vibrating screen, the liquid material outlet of the slurry vibrating screen is connected to the dissolution tank, the dissolution tank is connected to the feed end of the transverse expansion tube through a feeding pipe, and the feeding pipe is provided with a dissolution tank pump; the dissolution tank is also connected to the first low-pressure steam pipe.

[0012] As a further improvement, sight glasses are provided on the separation tower and the transverse expansion tube.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention breaks through the traditional crystallization method of using an agitator to stir and provide circulation power. It innovatively uses the method of feeding the crystal slurry tangentially along the separation tower of the crystallizer to generate swirling power, thereby achieving the dual goals of providing a motion environment for crystal growth and centrifugal separation of large-particle crystals. While greatly simplifying the crystallizer structure, it solves the problems of large return material volume and low production efficiency in traditional processes, and the particle size distribution is concentrated. The present invention changes the traditional method of cultivating crystals by mixing supersaturated slurry with crystals of different sizes. Instead, it adopts a crystal circulation method to send the bed crystals to the saturation point where they directly contact with the supersaturated solution and absorb the supersaturated slurry, thereby achieving the purpose of directional crystal cultivation. The present invention changes the traditional intermittent discharge and extraction method of crystals. The crystals are in a swirling motion state in the separation tower. Large crystal particles sink to the lower area along the wall of the separation tower under the action of centrifugal force and gravity to form a lower bed layer, while small particles and fine crystals are in the upper part of the separation tower. Crystals of different sizes form a normal distribution from bottom to top in the separation tower. After the crystal size is cultivated to meet the requirements, qualified crystals can be continuously extracted from the bottom of the separation tower under the premise of controlling the bed thickness. The present invention provides a favorable environment for the growth of crystals, has the characteristics of small system return material amount, stable product quality, low device energy consumption, and can realize the continuous production of qualified crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a structural diagram of an embodiment of the present invention; Figure 2 1 is a schematic structural diagram of a crystallizer according to an embodiment of the present invention; Figure 3 This is a photo of the 2.5-3mm ammonium sulfate crystals in Case 1; Figure 4 This is a photo of the ferrous sulfate crystals cultured for 8 hours in Case 2; Figure 5 This is a photo of the ferrous sulfate crystals cultured for 12 hours in Case 2.

[0016] In the figure: 1-crystallizer; 2-separation tower; 3-lateral expansion pipe; 4-vacuum pipe; 5-slurry vibrating screen; 6-dissolving tank; 7-feeding pipe; 8-dissolving tank pump; 9-first low-pressure steam pipe; 10-slurry circulation pipe; 11-slurry circulation pump; 12-slurry circulation heater; 13-second low-pressure steam pipe; 14-crystal circulation pipe; 15-crystal circulation addition port; 16-crystal circulation pump; 17-sight glass. DETAILED DESCRIPTION

[0017] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] like Figure 1 and Figure 2As shown, a cyclone type crystallization device can be used for producing ammonium sulfate, ammonium phosphate, ferrous sulfate and other soluble material crystallization device, including crystallizer 1, the crystallizer 1 includes vertically arranged separation tower 2, the separation tower 2 is hollow tower body, its diameter is 125 centimeters, height is 350 centimeters; One side of the separation tower 2 is fixedly installed with the transverse expansion pipe 3 extending along the tangent direction thereof, the transverse expansion pipe 3 is away from the one end of the separation tower 2 as the feed end, the end connected with the separation tower 2 as the discharge end, and the transverse expansion pipe 3 is conical with the diameter gradually expanding from the feed end to the discharge end, the angle of the cone is designed as 30°, the length of the transverse expansion pipe 3 is 186.25 centimeters, the diameter of the feed end thereof is 25 centimeters, and the diameter of the discharge end thereof is 125 centimeters. After the circulating slurry is cultured in the transverse expansion pipe 3, it enters the separation tower 2 along the tangent direction, so as to provide the cyclone power for the crystal circulation flow and the crystal separation, the slurry and the crystal are in the cyclone motion state in the separation tower 2, the large particle crystals are separated to the lower part along the cylinder wall of the separation tower 2 under the action of the centrifugal force and the gravity to form the lower bed layer, and the small particle and the fine crystal are in the upper part of the separation tower 2, and the crystals of different sizes form the normal distribution from bottom to top in the separation tower 2.

[0019] The upper end of the separation tower 2 is connected with the vacuum control system through the vacuum extraction pipe 4, the vacuum extraction pipe 4 is provided with a vacuum regulating valve PIC01 for controlling the vacuum degree of the crystallization.

[0020] The lower end of the separation tower 2 is inversely conical, the lower end of the separation tower 2 is connected with the slurry vibrating screen 5 through the pipeline for separating the mother liquor and the crystal, the pipeline between the lower end of the separation tower 2 and the slurry vibrating screen 5 is provided with a production valve HIC01, the crystal cultured in the separation tower 2 is continuously produced from the bottom production valve HIC01 to the slurry vibrating screen 5; The slurry vibrating screen 5 is provided with a solid material outlet for discharging the crystal and a liquid material outlet for discharging the mother liquor, the liquid material outlet of the slurry vibrating screen 5 is connected with the dissolving tank 6, and the dissolving tank 6 is used for mother liquor recovery and raw material preparation; The dissolving tank 6 is connected with the feed end of the transverse expansion pipe 3 through the feed pipe 7, the feed pipe 7 is provided with the dissolving tank pump 8, the prepared raw material is sent to the crystallizer 1 through the dissolving tank pump 8 to provide the supersaturation for the generation of new crystals and the growth of crystals, and the valves are arranged on the feed pipe 7 upstream and downstream of the dissolving tank pump 8; The dissolving tank 6 is also connected with the first low-pressure steam pipe 9, the dissolving tank temperature control valve TIC01 is arranged on the first low-pressure steam pipe 9 for controlling the solution temperature in the dissolving tank 6.

[0021] The system also includes a slurry circulation pipe 10. Its feed end is connected to one side of the separation tower 2 for extracting fine crystals from the upper layer of the separation tower 2. Its discharge end is connected to the feed end of the transverse expansion pipe 3. A slurry circulation pump 11 and a slurry circulation heater 12 are positioned sequentially along the material flow direction of the slurry circulation pipe 10. The slurry circulation pump 11 provides power for the flow and circulation of crystals within the transverse expansion pipe 3. The slurry circulation heater 12 controls the evaporation temperature and, to a certain extent, eliminates fine crystals. The vacuum control system controls the crystallization vacuum level. By controlling the evaporation temperature and vacuum level of the crystallizer 1, the system evaporation capacity is adjusted to create a favorable crystallization environment for crystal production and cultivation. The slurry circulation heater 12 can be a tubular heater. The slurry circulation pipe 10 is connected to the tube side of the slurry circulation heater 12. The shell side of the slurry circulation heater 12 is connected to a second low-pressure steam pipe 13. A slurry temperature control valve TIC09 is installed on the second low-pressure steam pipe 13 to maintain a constant slurry temperature TT09.

[0022] The system also includes a crystal circulation pipe 14, the feed end of which is connected to one side of the separation tower 2 and is lower than the feed end of the slurry circulation pipe 10. This pipe is used to remove small-particle crystals from the middle layer of the separation tower 2. The outer wall of the transverse expansion pipe 3 is provided with multiple crystal circulation inlets 15 evenly spaced along its length. Each inlet 15 has a diameter of 20 cm and is connected in parallel to the discharge end of the crystal circulation pipe 14 via pipelines. A valve is provided between each inlet 15 and the crystal circulation pipe 14. A crystal circulation pump 16 is provided on the crystal circulation pipe 14 to regulate the crystal circulation flow rate and prevent pipeline blockage. Valves are provided on the crystal circulation pipe 14 upstream and downstream of the crystal circulation pump 16. Crystal products of customer-specific sizes are cultivated through crystal circulation cultivation, and qualified crystal products are continuously extracted from the bottom of the separation tower 2.

[0023] In addition, slurry circulation pipe 10, located downstream of slurry circulation pump 11, is connected to crystal circulation pipe 14, located upstream and downstream of crystal circulation pump 16, via pipelines. Valves are provided on each of these pipelines. Opening the valves allows the clear liquid in slurry circulation pipe 10 to be injected into crystal circulation pipe 14, preventing blockage of crystal circulation pipe 14.

[0024] Sightglasses 17 are provided on both the separation tower 2 and the transverse expansion tube 3 for observing crystal growth within the crystallizer 1. In this embodiment, five sightglasses 17 are evenly spaced along the length of the transverse expansion tube 3. These five sightglasses are numbered 1-5 and are arranged in sequence along the direction of material flow within the transverse expansion tube 3. Six sightglasses 17 are evenly spaced vertically on the separation tower 2. These six sightglasses are numbered 6-11 and are arranged in sequence from bottom to top. Sightglass 9 is located at the same height as the transverse expansion tube 3.

[0025] Working Principle: As the material flows through the transverse expansion tube 3, the crystals continuously absorb supersaturation and grow. Unabsorbed supersaturation forms new crystals under the combined action of heat and water evaporation, which continue to grow. The slurry enters the separation tower 2 along a tangential direction, forming a vortex inside the separation tower 2. Large crystals sink to the bottom of the separation tower 2 under the influence of centrifugal force and gravity. Once the crystal size and thickness meet the specified specifications, they can be continuously removed from the bottom of the separation tower 2.

[0026] Specific process: Add production raw materials and water in a certain proportion to the dissolution tank 6, and control the solution temperature TI01 at a certain temperature by the dissolution tank temperature control valve TIC01; the water can be the condensed water discharged from the slurry circulation heater 12; Furthermore, the material in the dissolving tank 6 is fed into the transverse expansion pipe 3 of the crystallizer 1 through the dissolving tank pump 8. After the liquid level LT02 in the separation tower 2 of the crystallizer 1 reaches a certain value, the slurry circulation pump 11 and the crystal circulation pump 16 are started to establish system circulation; Furthermore, the vacuum control system is started, and the vacuum control valve PIC01 controls the vacuum degree PT01 of the crystallizer 1 at a certain value; the slurry circulation heater 12 is put into use, and the circulating slurry temperature TT09 is controlled at a certain temperature by the slurry temperature control valve TIC09. The evaporation amount of the crystallizer 1 is controlled at a certain amount by the temperature and vacuum degree of the crystallizer 1 (the evaporation amount is calculated and counted by the water separation system of the vacuum system); the slurry concentration can be adjusted and stabilized by the crystal circulation pump 16; Furthermore, the growth of the crystals in the transverse expansion tube 3 is observed through sight glasses 1-5, and the valve openings at the crystal circulation inlet 15 are adjusted in a timely manner to adjust the crystal addition situation at the crystal circulation inlet 15. The crystal circulation concentration can be adjusted by the crystal circulation pump 16; Among them, the formation of crystals in the slurry in the separation tower 2 can be observed through sight glasses No. 9-11, the size of the circulating crystals in the separation tower 2 can be observed through sight glasses No. 8, and the particle size and material layer thickness of the product in the separation tower 2 can be observed through sight glasses No. 6-7; Furthermore, after the crystals are circulated and cultivated and qualified, they are continuously extracted from the extraction valve HIC01 at the bottom of the separation tower 2 to the slurry vibrating screen 5. The crystals obtained by screening are added to the drying system for drying to obtain the product, and the mother liquor separated from the material enters the dissolution tank 6 as a raw material recovery system.

[0027] Through the form of crystal circulation cultivation, large-particle crystal products of different sizes can be produced according to production needs.

[0028] Case 1: Add ammonium sulfate raw material and water in a ratio of 1:1.2 to dissolution tank 6, and control the solution temperature TI01 at about 85°C by the dissolution tank temperature control valve TIC01, and optimize the amount of water added to control the solution specific gravity at about 1.245; Further, the material in the dissolving tank 6 is fed into the crystallizer 1 through the dissolving tank pump 8, and the feed flow rate FI01 is controlled at 2m 3 / h or so, after the liquid level LT02 in the crystallizer 1 reaches 70%, start the slurry circulation pump 11 to establish system circulation, and control the circulation flow rate at 15m 3 / h, and optimize and adjust the material flow swirl by observing the mirrors 17 of the crystallizer 1; start the crystal circulation pump 16 to establish crystal circulation, and control the circulation flow rate at 2m 3 / h, and optimize and adjust the circulation volume and the valve opening at each crystal circulation inlet 15 according to the crystal growth situation and crystal circulation situation; After the system establishes circulation, start the vacuum system and control the vacuum degree PT01 in the crystallizer 1 at about 42kPa through the vacuum regulating valve PIC01; put the slurry circulation heater 12 into use, and control the circulating slurry temperature TT09 at about 70°C through the slurry temperature control valve TIC09; by adjusting the temperature and vacuum degree of the crystallizer 1, control the evaporation rate of the crystallizer 1 at about 200L / h; the slurry concentration can be adjusted by the crystal circulation pump 16 to control the specific gravity at about 1.256; Furthermore, the growth of the crystals in the transverse expansion tube 3 is observed through the No. 1-5 sight glasses 17, and the crystal addition to each crystal circulation addition port 15 is adjusted in a timely manner. The crystal circulation concentration can be adjusted by the crystal circulation pump 16 to control the crystal ratio to about 30% to prevent pipe blockage; The formation of crystals in the slurry in separation tower 2 can be observed through sight glasses No. 9-11, the size of circulating crystals can be observed through sight glasses No. 8, and the product particle size and material layer thickness can be observed through sight glasses No. 6-7; Furthermore, after the crystals are circulated and cultivated and qualified, they are continuously extracted from the extraction valve HIC01 at the bottom of the separation tower 2 to the slurry vibrating screen 5. The crystals obtained by screening are added to the drying system for drying to obtain the product, and the mother liquor separated from the material enters the dissolution tank 6 as a raw material recovery system.

[0029] By cultivating crystals in a circulating culture for 6 hours, crystal products with a size of about 2 mm can be continuously produced, of which the proportion of 1.8-2.2 mm crystals can reach 90%.

[0030] By cultivating crystals in a circulating culture for 8 hours, crystal products with a size of about 2.5-3mm can be continuously produced, of which the proportion of 2.5-3mm crystals can reach 88%.

[0031] Case 2: Add ferrous sulfate heptahydrate raw material and water in a ratio of 4:1 to dissolving tank 6, and control the solution temperature TI01 at about 55°C by dissolving tank temperature control valve TIC01, and optimize the amount of water added to control the solution specific gravity at about 1.350; Further, the material in the dissolving tank 6 is fed into the crystallizer 1 through the dissolving tank pump 8, and the feed flow rate FI01 is controlled at 2m 3 / h, after the liquid level LT02 in the crystallizer 1 reaches 70%, the slurry circulation pump 11 is started to establish system circulation, and the circulation flow rate is controlled at 15m by adjusting the frequency of the slurry circulation pump 11. 3 / h, and optimize and adjust the material flow swirl by observing the mirrors 17 of the crystallizer 1; start the crystal circulation pump 16 to establish crystal circulation, and control the circulation flow rate at 2m 3 / h, and optimize and adjust the circulation volume and the valve opening at each crystal circulation inlet 15 according to the crystal growth situation and crystal circulation situation; After the system establishes circulation, start the vacuum system and control the vacuum degree PT01 in the crystallizer 1 at about 42kPa through the vacuum regulating valve PIC01; put the slurry circulation heater 12 into use, and control the circulating slurry temperature TT09 at about 35°C through the slurry temperature control valve TIC09; by adjusting the temperature and vacuum degree of the crystallizer 1, control the evaporation rate of the crystallizer 1 at about 200L / h; the slurry concentration can be adjusted by the crystal circulation pump 16 to control the specific gravity at about 1.256; Furthermore, the growth of the crystals in the transverse expansion tube 3 is observed through the sight glasses 1-5, and the crystal addition to each crystal circulation addition port 15 is adjusted in a timely manner. The crystal circulation concentration can be adjusted by the crystal circulation pump 16 to control the crystal ratio to about 30% to prevent pipe blockage; The formation of crystals in the slurry in separation tower 2 can be observed through sight glasses No. 9-11, the size of circulating crystals can be observed through sight glasses No. 8, and the product particle size and material layer thickness can be observed through sight glasses No. 6-7; Furthermore, after the crystals are circulated and cultivated and qualified, they are continuously extracted from the extraction valve HIC01 at the bottom of the separation tower 2 to the slurry vibrating screen 5. The crystals obtained by screening are added to the drying system for drying to obtain the product, and the mother liquor separated from the material enters the dissolution tank 6 as a raw material recovery system.

[0032] Through crystal circulation culture, which takes 8 hours, crystal products with a size of about 2mm can be continuously produced, of which the proportion of 1.8-2.2mm crystals can reach 90%.

[0033] By cultivating crystals in a circulating culture for 12 hours, crystal products with a size of about 2.5-3mm can be continuously produced, of which the proportion of 2.5-3mm crystals can reach 90%.

[0034] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A cyclone crystallization device, characterized in that: The invention comprises a crystallizer (1), wherein the crystallizer (1) comprises a vertically arranged separation tower (2), and a transverse expansion tube (3) extending along the tangent direction of the separation tower (2) is provided on one side of the separation tower (2), wherein the end of the transverse expansion tube (3) away from the separation tower (2) is a feed end, and the end connected to the separation tower (2) is a discharge end, and the transverse expansion tube (3) is in a conical shape with a diameter gradually increasing from the feed end to the discharge end.

2. A cyclone crystallization device according to claim 1, characterized in that: The system further comprises a slurry circulation pipe (10), wherein the feed end of the slurry circulation pipe (10) is connected to one side of the separation tower (2), the discharge end of the slurry circulation pipe (10) is connected to the feed end of the transverse expansion pipe (3), and the slurry circulation pipe (10) is provided with a slurry circulation pump (11) and a slurry circulation heater (12).

3. A cyclone crystallization device according to claim 2, characterized in that: The invention also includes a crystal circulation pipe (14), the feed end of the crystal circulation pipe (14) is connected to one side of the separation tower (2), the outer wall of the transverse expansion pipe (3) is provided with a plurality of crystal circulation addition ports (15) evenly spaced along the length direction thereof, the plurality of crystal circulation addition ports (15) are respectively connected to the discharge end of the crystal circulation pipe (14), and the crystal circulation pipe (14) is provided with a crystal circulation pump (16).

4. A cyclone crystallization device according to claim 3, characterized in that: The feed end of the crystal circulation pipe (14) is lower than the feed end of the slurry circulation pipe (10).

5. A cyclone crystallization device according to claim 1, characterized in that: The upper end of the separation tower (2) is connected to a vacuum control system.

6. A cyclone crystallization device according to claim 1, characterized in that: The separation tower (2) is a hollow tower body, and the lower end of the separation tower (2) is arranged in an inverted cone shape.

7. A cyclone crystallization device according to claim 1, characterized in that: The lower end of the separation tower (2) is connected to a slurry vibrating screen (5), the liquid material outlet of the slurry vibrating screen (5) is connected to a dissolving tank (6), the dissolving tank (6) is connected to the feed end of the transverse expansion tube (3) via a feeding pipe (7), and a dissolving tank pump (8) is provided on the feeding pipe (7); the dissolving tank (6) is also connected to a first low-pressure steam pipe (9).

8. The cyclone crystallization device according to claim 1, wherein: The separation tower (2) and the transverse expansion tube (3) are both provided with sight glasses (17).

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