A continuous crystallization device for p-nitrotoluene

Abstract

The invention relates to the technical field of p-nitrotoluene crystallization equipment, and specifically to a continuous crystallization device for p-nitrotoluene, wherein the liquid material in the crystallizer is cooled and the p-nitrotoluene crystal material is gradually precipitated, the remaining mother liquor is continuously discharged from the liquid outlet, and the liquid material is pumped toward the upper liquid surface along the guide tube to achieve a circulating cooling crystallization effect, when the nut pulls the connecting rope downward, the annular filter screen is pulled by the connecting rope and gradually expands elastically toward its inner circle until its inner circle abuts against the outer wall of the guide tube, and the barb abuts against the inner side of the sealing block, so that the inner circle of the annular filter screen keeps abutting against the outer wall of the guide tube until the nut moves upward to drive the connecting rope to pass upward out of the vertical groove, the annular filter screen elastically contracts, and the crystal material on the annular filter screen tilts downward and falls into a fixed collector, thereby realizing a convenient and efficient process of extracting and precipitating crystal material in the process of continuous feeding and discharging, and improving the crystallization processing efficiency of p-nitrotoluene.

Description

Technical Field

[0001] The invention relates to the technical field of p-nitrotoluene crystallization equipment, in particular to a p-nitrotoluene continuous crystallization device. Background Art

[0002] In the existing nitrotoluene separation and crystallization process, a mixed nitrotoluene raw material is usually used for multiple distillation, rectification and crystallization treatments. Specifically, the mixed nitrotoluene raw material is treated by light removal, heavy removal and ortho-separation to obtain a mixed product of p-nitrotoluene and m-nitrotoluene. Considering that the melting point of p-nitrotoluene is 52 to 54°C and the melting point of m-nitrotoluene is about 15°C, the mixed product can be cooled and crystallized in a crystallizer to separate and precipitate p-nitrotoluene, and the m-nitrotoluene mother liquor is sent to the meta-column for further separation to produce the m-nitrotoluene product. In this regard, the existing conventional cooling crystallizer can be used in the crystallization process of p-nitrotoluene, especially the continuous cooling crystallizer, which adopts the method of continuous feeding and continuous discharging, can effectively improve the production efficiency and occupy a small area. In the prior art, such as the continuous multi-stage constant temperature difference cooling crystallizer disclosed in Chinese patent document CN109893880A, CN115105853A A disclosed vertical continuous cooling crystallizer, etc., all adopt a similar basic structural principle of continuous cooling crystallization, but achieve a better crystallization effect by designing and improving different material circulation channels and stirring mechanisms in the crystallizer. However, the existing continuous cooling crystallizers, including most of the above, still cannot further conveniently and efficiently extract the precipitated crystal material, which also affects the crystallization efficiency and the mother liquor discharge efficiency to a certain extent, and then affects the crystallization processing efficiency of para-nitrotoluene. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a continuous crystallization device for para-nitrotoluene to solve the problem that the existing continuous cooling crystallizer cannot further conveniently and efficiently extract the precipitated crystal material, thereby affecting the crystallization processing efficiency of para-nitrotoluene.

[0004] Based on the above purpose, the present invention provides a continuous crystallization device for p-nitrotoluene, including a crystallizer, a jacket is provided on the outer side of the crystallizer, and a cooling medium is passed into the jacket:

[0005] The top of the crystallizer is provided with a liquid inlet for continuous input of liquid material, and the bottom of the crystallizer is provided with a liquid outlet. The liquid material in the crystallizer cools down and gradually precipitates p-nitrotoluene crystal material, and the remaining mother liquor is continuously discharged through the liquid outlet;

[0006] A guide tube is vertically arranged in the crystallizer, and the top and bottom of the guide tube are both open designs. A main shaft is rotatably connected in the crystallizer, and the main shaft passes through the bottom end of the guide tube and is connected to a guide blade, which is used to pump the liquid along the guide tube to the liquid surface above the guide tube;

[0007] The main shaft is located between its top and the guide blades at a position of a reciprocating thread section, and a nut is meshed and connected to the reciprocating thread section to drive the nut to move up and down reciprocatingly. A fixed collector is provided around the inner wall of the top of the crystallizer, and an annular filter is connected to the inner circle of the top of the fixed collector, and a connecting rope is connected to the inner circle of the annular filter along its radial direction.

[0008] A vertical groove for the connecting rope to pass through is vertically opened on the side wall of the guide cylinder. Multiple sealing blocks are arranged on both sides of the vertical groove from top to bottom. The sealing blocks on both sides pop out and abut against each other to seal the vertical groove. The outer side of the sealing block is designed with an inclined end face. Multiple barbs are arranged at intervals on the end of the connecting rope close to the annular filter. When the nut pulls the connecting rope downward, the barbs enter the guide cylinder by pushing the inclined end face of the sealing block. The annular filter is pulled by the connecting rope and gradually expands elastically toward its inner circle until the nut moves down to the bottom end of the reciprocating thread section. The inner circle of the annular filter abuts against the outer wall of the guide cylinder. As the nut moves upward, the barbs abut against the inner side of the sealing block until the connecting rope passes upward out of the vertical groove. The annular filter elastically contracts, and the crystal material on the annular filter tilts downward and falls into the fixed collector.

[0009] Preferably, the liquid inlet is located above the outer side of the guide tube, and the liquid inlet is externally connected to a liquid inlet pipe.

[0010] Preferably, the bottom end of the crystallizer is funnel-shaped, and a diaphragm is connected to the expanded end of the funnel. The diaphragm is hollowed out at the position below and outside the guide tube, and the hollowed-out portion is covered with a filter membrane.

[0011] Preferably, the bottom end of the crystallizer is rotatably connected to a low-speed agitator, and the liquid outlet is located at one side of the bottom end of the crystallizer.

[0012] Preferably, an elastic band is wound around the inner circle of the annular filter screen. When the annular filter screen elastically contracts, the elastic band is pulled to extend along the circumferential direction of the inner circle of the annular filter screen.

[0013] Preferably, in the initial state, the width direction of the elastic band is perpendicular to the plane of the annular filter screen, and the inner ring of the annular filter screen is connected to the vertical middle position of the elastic band.

[0014] Preferably, a movable collector is provided at the bottom end of the fixed collector, and a connecting rod is connected to the bottom of the main shaft and is connected to the movable collector through the connecting rod, so as to drive the movable collector to rotate synchronously. The top of the movable collector is connected to the bottom end of the fixed collector, and a water filter membrane is obliquely provided at the middle part of the movable collector. A leakage port is provided on the side of the movable collector facing the crystallizer, and a discharge port is correspondingly provided on the crystallizer. The crystal material falls into the movable collector along the fixed collector, and is discharged obliquely outward along the water filter membrane, the leakage port and the discharge port in sequence.

[0015] Preferably, a vibrating rod is connected to the upwardly inclined end of the water filter membrane, a boss is provided on the inner side wall of the fixed collector, a convex tooth is provided on the bottom end surface of the boss, and the bottom of the vibrating rod is vertically slidably connected to the movable collector. When the movable collector rotates, the top end of the vibrating rod slides along the convex tooth and vibrates up and down.

[0016] Preferably, a scraper is provided at the side end of the connecting rod for rotating and cleaning the inner wall of the crystallizer.

[0017] When the nut drives the ring to move up and away from the magnetic block, the pin moves up and is inserted into the insertion hole, so that the nut and the ring remain in a state of being engaged with each other.

[0018] The beneficial effects of the present invention are as follows: the liquid material in the crystallizer is cooled and the crystal material of para-nitrotoluene is gradually precipitated, and the remaining meta-nitrotoluene mother liquor is continuously discharged from the liquid outlet, and the liquid material is pumped to the upper liquid surface along the guide tube by the continuously rotating guide blade, and the circulating pumped liquid material and the newly added liquid material continue to flow downward along the outer side of the guide tube, so as to achieve a good circulation cooling crystallization effect. When the nut pulls the connecting rope downward, the barb enters the guide tube by pushing the inclined end face of the sealing block, and the annular filter screen is pulled by the connecting rope and gradually expands elastically toward its inner ring, until the nut moves down to the bottom end of the reciprocating thread section, and the inner ring of the annular filter screen abuts against the outer wall of the guide tube, and the circulation The pumped liquid and the newly added liquid flow downward along the outside of the guide tube, cool and precipitate above the annular filter screen, and the precipitated crystals are blocked by the annular filter screen and move upward along the reciprocating thread section with the nut. The barb abuts against the inner end face of the sealing block and cannot pass through the outside of the guide tube, so that the inner circle of the annular filter screen remains abutted against the outer wall of the guide tube until the nut moves upward to drive the connecting rope to pass upward out of the vertical groove, the barb loses its restraint, the annular filter screen elastically contracts, and the crystals on the annular filter screen tilt downward and fall into the fixed collector, thereby realizing a convenient and efficient process of extracting and precipitating crystals in the process of continuous feeding and discharging, thereby improving the crystallization treatment efficiency of para-nitrotoluene. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 For the present invention Figure 1 The enlarged schematic diagram of point A in the middle;

[0022] Figure 3 For the present invention Figure 1 The enlarged schematic diagram of point B in the middle;

[0023] Figure 4 It is a structural schematic diagram of the vertical groove and the sealing block of the present invention;

[0024] Figure 5 It is a schematic diagram of the top view of the structure of the annular filter screen of the present invention when it is elastically contracted;

[0025] Figure 6 For the present invention Figure 5 The enlarged schematic diagram of the center C;

[0026] Figure 7 It is a schematic diagram of the top view of the structure of the annular filter screen of the present invention when it is elastically expanded toward its inner circle;

[0027] Figure 8 It is a schematic diagram of the overall structure of another embodiment of the present invention;

[0028] Fig. 9 For the present invention Figure 8 A schematic diagram of the structure of the nut and the collar;

[0029] Fig.10 It is a structural schematic diagram of the nut of the present invention when it is separated from the collar;

[0030] Fig.11 It is a schematic structural diagram of the annular filter screen of the present invention when it starts to collect materials once;

[0031] Fig.12 For the present invention Fig.11 A schematic diagram of the structure when the middle nut and the collar are engaged;

[0032] Fig.13 It is a structural schematic diagram of the nut and the collar in the aggregate transfer of the annular filter of the present invention;

[0033] Fig.14It is a structural schematic diagram of the crystal material on the annular filter screen of the present invention when the crystal material falls obliquely;

[0034] Fig.15 For the present invention Fig.14 Enlarged schematic diagram of point D in the middle.

[0035] The markings in the figure are:

[0036] 1. Crystallizer; 2. Jacket; 3. Liquid inlet; 31. Liquid inlet pipe; 4. Liquid outlet; 5. Guide tube; 51. Vertical slot; 52. Sealing block; 6. Main shaft; 7. Guide blade; 8. Nut; 81. Ring; 82. Limit pin; 83. Limit hole; 84. Latch; 9. Fixed collector; 10. Annular filter; 11. Connecting rope; 12. Barb; 13. Transverse partition; 14. Low-speed agitator; 15. Elastic band; 16. Movable collector; 17. Connecting rod; 18. Water filter membrane; 19. Leakage port; 20. Discharge port; 21. Vibrating rod; 22. Boss; 23. Magnetic block; 24. Elastic telescopic rod; 25. Pressing sheet; 26. Pull rope. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0038] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, a continuous crystallization device for p-nitrotoluene comprises a crystallizer 1, a jacket 2 is arranged on the outer side of the crystallizer 1, a cooling medium is introduced into the jacket 2, a liquid inlet 3 is arranged on the top of the crystallizer 1 for continuously feeding liquid material, a liquid outlet 4 is arranged on the bottom of the crystallizer 1, the liquid material in the crystallizer 1 is cooled and p-nitrotoluene crystal material is gradually precipitated, and the remaining mother liquid is continuously discharged through the liquid outlet 4, a guide tube 5 is vertically arranged in the crystallizer 1, the top and bottom ends of the guide tube 5 are both open, a main shaft 6 is rotatably connected in the crystallizer 1, and the main shaft 6 The main shaft 6 is parallel to and penetrates the guide tube 5. A guide blade 7 is connected to the bottom end of the guide tube 5 on the main shaft 6, which is used to pump the liquid along the guide tube 5 to the liquid surface above the guide tube 5. The main shaft 6 is located between its top and the guide blade 7. A reciprocating thread section is provided. A nut 8 is meshed and connected to the reciprocating thread section, which is used to drive the nut 8 to move up and down. A fixed collector 9 is provided around the inner wall of the top of the crystallizer 1. The top of the fixed collector 9 is open. The inner circle of the top of the fixed collector 9 is connected to an annular filter 1. 0, the inner ring of the annular filter 10 is connected with a connecting rope 11 along its radial direction, and a vertical groove 51 for the connecting rope 11 to pass through is vertically opened on the side wall of the guide tube 5, and multiple sealing blocks 52 are arranged on both sides of the vertical groove 51 from top to bottom. The sealing blocks 52 on both sides pop out and abut against each other to seal the vertical groove 51. The outer side of the sealing block 52 is designed with an inclined end face. A plurality of barbs 12 are arranged at intervals on one end of the connecting rope 11 close to the annular filter 10. When the nut 8 pulls the connecting rope 11 downward, the barbs 12 push the sealing blocks The annular filter screen 10 is pulled by the connecting rope 11 and gradually expands elastically toward its inner circle until the nut 8 moves down to the bottom end of the reciprocating thread section, and the inner circle of the annular filter screen 10 abuts against the outer wall of the guide tube 5. As the nut 8 moves up along the reciprocating thread section, the barb 12 abuts against the inner end surface of the sealing block 52 until the connecting rope 11 passes through the vertical groove 51 upward, and the annular filter screen 10 elastically contracts, and the crystal material on the annular filter screen 10 tilts downward and falls into the fixed collector 9.

[0040] The present invention is based on the basic structural principle of the existing separation crystallization equipment for nitrotoluene, especially the continuous cooling crystallization equipment, and comprises a crystallizer 1, a jacket 2 is arranged on the outside of the crystallizer 1, a cooling medium is introduced into the jacket 2, and is used to generate heat exchange with the crystallizer 1, a liquid inlet 3 is arranged on the top of the crystallizer 1, and is used to continuously input liquid material, that is, a mixed liquid material of p-nitrotoluene and m-nitrotoluene, a liquid outlet 4 is arranged on the bottom of the crystallizer 1, and the liquid material in the crystallizer 1 is cooled and the p-nitrotoluene crystal material is gradually precipitated, and the remaining m-nitrotoluene mother liquor is continuously discharged through the liquid outlet 4. In particular, the crystallizer 1 is A guide tube 5 is vertically provided. Specifically, the guide tube 5 can be designed as a cylindrical structure coaxial with the crystallizer 1, except that the top and bottom ends of the guide tube 5 are both open designs. A main shaft 6 is rotatably connected in the crystallizer 1. The top end of the main shaft 6 passes through the crystallizer 1 and is connected to a driving mechanism outside the top end of the crystallizer 1 to drive the main shaft 6 to continuously rotate axially. The main shaft 6 runs through the guide tube 5 in parallel. A guide blade 7 is connected to the bottom end of the guide tube 5 on the main shaft 6, so as to avoid forming a dead zone in the middle position of the crystallizer 1. The liquid material is pumped along the guide tube 5 to the top of the guide tube 5 by the continuously rotating guide blade 7. The liquid level, the circulating pumped liquid and the newly added liquid continue to flow downward along the outside of the guide tube 5, achieving a good circulating cooling crystallization effect, wherein the position between the top of the main shaft 6 and the guide blade 7 is a reciprocating thread section, that is, similar to the existing conventional reciprocating screw mechanism, the reciprocating thread section is meshed with a nut 8, which is used to drive the nut 8 to move up and down, and the top of the crystallizer 1 is provided with a fixed collector 9 around its inner wall, that is, the fixed collector 9 is an annular material box structure fixed to the top of the crystallizer 1, the top of the fixed collector 9 is an open design, and the top inner circle of the fixed collector 9 An annular filter screen 10 is connected, wherein the annular filter screen 10 adopts an existing conventional filter screen structure with a certain elasticity. The inner circle of the annular filter screen 10 is connected with a connecting rope 11 along its radial direction. A vertical groove 51 for the connecting rope 11 to pass through is vertically opened on the side wall of the guide tube 5. The top of the vertical groove 51 is open. A plurality of sealing blocks 52 are arranged on both sides of the vertical groove 51 from top to bottom. The sealing blocks 52 are connected to the inside of the vertical groove 51 through elastic components such as springs. The sealing blocks 52 on both sides are in an initial pop-up and abutting state, which is used to seal the vertical groove 51 to prevent the liquid from directly flowing out of the vertical groove 51. Figure 4 , Figure 5 , Figure 6 As shown, the outer side of the sealing block 52 is designed as an inclined end face, and the inner side of the sealing block 52 is a plane or arc-shaped end face connected to the cylinder wall of the guide cylinder 5. A plurality of barbs 12 are arranged at intervals on one end of the connecting rope 11 close to the annular filter screen 10, as shown in FIG. Figure 1 , Figure 3As shown, the barb 12 can be specifically designed to be L-shaped, and the L-shaped short side of the barb 12 is vertically fixed to the connecting rope 11, and the L-shaped long side of the barb 12 is vertically fixed to the end of the L-shaped short side of the barb 12 facing the annular filter 10;

[0041] Thus, when the nut 8 pulls the connecting rope 11 downward, the barb 12 enters the guide tube 5 by pushing the inclined end surface of the sealing block 52, and the annular filter screen 10 is pulled by the connecting rope 11 and gradually expands elastically toward its inner circle until the nut 8 moves downward to the bottom end of the reciprocating thread section. Figure 1 , Figure 7 As shown in the figure, the inner ring of the annular filter screen 10 abuts against the outer wall of the guide tube 5, the liquid material pumped by the circulating pump and the newly added liquid material flow downward along the outer side of the guide tube 5, cool and precipitate above the annular filter screen 10, and the precipitated crystal material is blocked by the annular filter screen 10, and moves upward along the reciprocating thread section with the nut 8. Since the barb 12 abuts against the inner end surface of the sealing block 52, it cannot pass through the outside of the guide tube 5, so that the inner ring of the annular filter screen 10 remains abutted against the outer wall of the guide tube 5 until the nut 8 moves upward to drive the connecting rope 11 to pass upward outside the vertical groove 51, the barb 12 loses its restraint, and the annular filter screen 10 elastically contracts. Figure 5 , Fig.14 As shown, the crystal material on the annular filter screen 10 falls obliquely downward into the fixed collector 9, thereby realizing a convenient and efficient process of extracting and precipitating the crystal material during the continuous feeding and discharging process, thereby improving the crystallization processing efficiency of p-nitrotoluene.

[0042] Among them, the liquid level in the crystallizer 1 is located between the top of the fixed collector 9 and the top of the guide tube 5. The top of the guide tube 5 can be fixedly connected to the top of the crystallizer 1 through a vertical rod (not shown in the figure). The position of the vertical rod is staggered with the vertical groove 51 to avoid affecting the movement of the connecting rope 11.

[0043] Among them, the L-shaped long side of a barb 12 closest to the annular filter screen 10 can be designed as an elastic telescopic structure, similar to the existing conventional elastic telescopic rod. When the nut 8 drives the connecting rope 11 to move upward, it avoids being affected by the barb 12. In addition, the top and bottom ends of the sealing block 52 can be chamfered to facilitate the up and down movement of the connecting rope 11. Even if a small chamfer causes a small amount of material leakage, it does not affect the circulation crystallization in the crystallizer 1.

[0044] In an embodiment of the present invention, Figure 1 As shown, the liquid inlet 3 is located above the outer side of the guide tube 5, and the liquid inlet 3 is externally connected to a liquid inlet pipe 31.

[0045] In an embodiment of the present invention, Figure 1As shown, the bottom end of the crystallizer 1 is funnel-shaped, and a transverse partition 13 is connected to the expanded end of the funnel. The position of the transverse partition 13 located on the outside below the guide tube 5 is a hollow design, that is, the position directly opposite to the bottom of the guide tube 5 is a solid plate, and the hollow part is covered with a filter membrane to prevent the crystal material from being directly discharged along the liquid outlet 4.

[0046] Optional, such as Figure 1 As shown, the bottom end of the crystallizer 1 is rotatably connected to a low-speed agitator 14 , which can be driven to rotate independently by a driving mechanism outside the bottom end of the crystallizer 1 , which is conducive to efficient liquid discharge. The liquid outlet 4 is located on one side of the bottom end of the crystallizer 1 .

[0047] In an embodiment of the present invention, Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, an elastic band 15 is wound around the inner circle of the annular filter screen 10. The elastic band 15 can be in a thin ring shape with a small elastic force, so that when the annular filter screen 10 elastically contracts, the elastic band 15 is pulled to extend along the circumferential direction of the inner circle of the annular filter screen 10.

[0048] In an embodiment of the present invention, Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, in the initial state, the width direction of the elastic band 15 is perpendicular to the plane of the annular filter screen 10, and the inner ring of the annular filter screen 10 is connected to the vertical middle position of the elastic band 15, so that when the crystal material on the annular filter screen 10 falls into the fixed collector 9 in an inclined downward direction, as shown in FIG. Fig.14 As shown, the elastic band 15 is used to limit the movement, which further facilitates the crystal material to fall into the fixed collector 9 efficiently, and prevents the crystal material from leaking along the inner circle of the annular filter screen 10. At the same time, when the inner circle of the annular filter screen 10 abuts against the outer wall of the guide tube 5, as shown in FIG. Figure 1 , Figure 3 As shown, the gap between the upper and lower adjacent sealing blocks 52 is sealed by the elastic band 15 to prevent leakage. Even if a small amount of leakage occurs, it will be pumped to the liquid surface by the guide blades 7 and crystallize above the annular filter screen 10.

[0049] In an embodiment of the present invention, Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, a movable collector 16 is provided at the bottom end of the fixed collector 9, a connecting rod 17 is connected to the bottom of the main shaft 6, and is connected to the movable collector 16 through the connecting rod 17. The movable collector 16 is an annular material box structure identical to the fixed collector 9, but is not fixed in the crystallizer 1, but is driven by the connecting rod 17 to rotate synchronously along the inner wall of the crystallizer 1, and the top of the movable collector 16 is connected to the bottom end of the fixed collector 9, wherein the joint between the movable collector 16 and the fixed collector 9 may be higher than the liquid level, and a sealing ring may be provided at the joint, and it is only necessary to ensure that a large amount of crystal material will not leak out, and it is better, as Figure 1 , Figure 2 As shown, a water filter membrane 18 is obliquely provided at the middle part of the movable collector 16 for filtering out a small amount of liquid in the crystal material downwards, a leakage port 19 is provided on the side of the movable collector 16 facing the crystallizer 1, and a discharge port 20 is correspondingly provided on the crystallizer 1. Specifically, the discharge port 20 can be fixed on both sides of the crystallizer 1, and 1 to 6 leakage ports 19 can be correspondingly provided along the outer ring of the movable collector 16, so that the crystal material falls into the movable collector 16 along the fixed collector 9, and is quickly swung in the fixed collector 9, which is beneficial to filtering out the liquid in the crystal material, and the dry crystal material is discharged outwardly along the water filter membrane 18, the leakage port 19 and the discharge port 20 in sequence.

[0050] Better, such as Figure 1 , Figure 2 As shown, a vibration rod 21 is connected to one end of the water filter membrane 18 that is tilted upward. A plurality of vibration rods 21 may be arranged at intervals along the inner circle of the water filter membrane 18. A boss 22 is provided on the inner side wall of the fixed collector 9. A convex tooth is provided on the bottom end surface of the boss 22. The bottom of the vibration rod 21 is vertically slidably connected to the movable collector 16. When the movable collector 16 rotates, the top end of the vibration rod 21 slides along the convex tooth and vibrates up and down, driving the water filter membrane 18 to vibrate synchronously, which is beneficial to further efficiently filter out the liquid material in the crystal material. Moreover, the setting of the boss 22 will not affect the falling of the crystal material.

[0051] More preferably, a leakage port 19 may be provided on the movable collector 16 below the water filter membrane 18, and a liquid outlet pipe may be provided on the crystallizer 1 for discharging the filtered liquid. The filtered liquid can also be circulated into the crystallizer 1 to continue the crystallization operation. Multiple crystallizers 1 can be connected in series to realize multi-stage continuous crystallization operations.

[0052] In an embodiment of the present invention, Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, the side end of the connecting rod 17 is provided with a scraper for rotating and cleaning the inner wall of the crystallizer 1. The bottom end of the connecting rod 17 may also be provided with a scraper for rotating and cleaning the filter membrane on the diaphragm 13. Alternatively, the connecting rod 17 may also pass downward through the diaphragm 13 and be connected to the rotating shaft of the low-speed agitator 14.

[0053] As another optional embodiment of the present invention, Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 , Fig.15 As shown, a magnetic block 23 is further provided at the bottom of the guide tube 5. Specifically, the magnetic block 23 can be connected to the inner wall of the guide tube 5 through a cross bar (not shown in the figure), so that although the magnetic block 23 is sleeved on the main shaft 6, it does not rotate with the main shaft 6. A collar 81 is sleeved on the outer side of the nut 8, and a limit pin 82 is elastically inserted in the side end of the collar 81 laterally. A limit hole 83 is correspondingly provided at the side end of the nut 8, and a plug 84 is elastically inserted in the bottom end of the collar 81 vertically. A plug hole is correspondingly provided on the limit pin 82, wherein the outer end of the limit pin 82 can be connected to the collar 81 through an elastic component such as a spring, which is used to pull the limit pin 82 to move inward laterally, and the bottom end of the plug 84 can be connected to the collar 81 through an elastic component such as a spring, which is used to pull the plug 84 upward, and the bottom end of the plug 84 can be connected to a pin cap, and a protrusion can be correspondingly provided at the top of the magnetic block 23, such as Fig.11 , Fig.12 As shown, when the nut 8 moves down to the bottom end of the reciprocating threaded section, the magnetic block 23 magnetically attracts the collar 81 and the latch 84, so that the top of the latch 84 moves down and out of the insertion hole. At the same time, an elastic telescopic rod 24 is erected at the top of the inner ring of the annular filter 10, and a pressing piece 25 is connected to the top of the elastic telescopic rod 24. One end of the pressing piece 25 is connected to a pull rope 26. Specifically, one end of the pull rope 26 can pass through the mesh of the annular filter 10 and pass through or cross the elastic band 15, and contact with the limit The outer end of the pin 82 is connected to each other and is used to pull the limit pin 82 to pop outward. As the crystal material above the annular filter screen 10 increases, the agglomerated crystal material is gradually precipitated on the annular filter screen 10 due to its own gravity and the water flow sucked downward. When the accumulated crystal material is pressed, the limit pin 82 moves inward and is inserted into the limit hole 83 when the pressing sheet 25 moves downward, so that the nut 8 is engaged with the ring 81. At this time, the nut 8 drives the ring 81 to continue to move upward and away from the magnetic block 23. Fig.13 As shown, after the latch 84 leaves the magnetic block 23, it elastically moves upward and is inserted into the insertion hole, so that the nut 8 and the collar 81 remain in a state of being engaged with each other, so that Fig.14 , Fig.15As shown, the crystal material on the annular filter screen 10 is driven to fall obliquely downward into the fixed collector 9, thereby completing a collection. After a collection, the nut 8 and the collar 81 continue to move downward until they move to the bottom end of the reciprocating thread section. Figure 8 , Fig. 9 As shown, at this time, the protrusion first contacts and magnetically absorbs the latch 84 to unlock the latch 84. In addition, due to the lack of pressure from the crystal material and the effect of the water flow during the downward movement, the pressing piece 25 naturally tends to move upward. At the moment when the latch 84 is unlocked, the pressing piece 25 immediately drives the pull rope 26 to pull out the limit pin 82. At this time, the collar 81 is separated from the clamping of the nut 8 and is absorbed on the magnetic block 23. At this time, as shown in FIG. Fig.10 As shown, the nut 8 continues to reciprocate up and down along the reciprocating thread section, but the collar 81 remains adsorbed on the magnetic block 23 until the crystal material above the annular filter screen 10 increases and the pressing plate 25 moves down again. Fig.11 , Fig.12 , Fig.13 , Fig.14 , Fig.15 As shown, a material collection action is performed again, and crystal material settling time is left between each material collection action to avoid frequent and continuous material collection actions of the annular filter screen 10;

[0054] Alternatively, the limit pin 82 may also be designed with an existing conventional electric telescopic rod structure, and the bottom end of the latch 84 may be connected to an existing conventional timer switch, thereby eliminating the need to set the elastic telescopic rod 24, the pressing sheet 25 and the pull rope 26. After a collection, the nut 8 and the collar 81 move downward until they reach the bottom end of the reciprocating threaded section. Figure 8 , Fig. 9 As shown, the protrusion first contacts and magnetically absorbs the latch 84 to unlock the latch 84 and trigger the timing switch at the same time. The timing switch triggers the inner end of the limit pin 82 to contract and unlock. At this time, the collar 81 is separated from the clamping of the nut 8 and is absorbed on the magnetic block 23. After a predetermined time, the timing switch triggers the inner end of the limit pin 82 to extend. When the nut 8 moves down to the bottom end of the reciprocating thread section, as shown in FIG. Fig.11 , Fig.12 As shown, the nut 8 is engaged with the collar 81, and the collar 81 is driven to move upward to complete a material collection process.

[0055] Among them, a limit block similar to the sealing block 52 is provided at the bottom end of the nut 8, and the bottom end of the limit block is designed with an inclined end face, so that the limit pin 82 can push the inclined end face of the limit block and penetrate upward into the limit hole 83. After penetrating into the limit hole 83, the limit pin 82 is abutted by the plane at the top of the limit block and cannot pass downward out of the limit hole 83.

[0056] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A continuous crystallization device for para-nitrotoluene, comprising a crystallizer (1), wherein a jacket (2) is provided on the outer side of the crystallizer (1), and a cooling medium is passed into the jacket (2), wherein: The top of the crystallizer (1) is provided with a liquid inlet (3), and the bottom of the crystallizer (1) is provided with a liquid outlet (4); the liquid material in the crystallizer (1) is cooled and p-nitrotoluene crystal material is gradually precipitated, and the remaining mother liquid is continuously discharged through the liquid outlet (4); A guide tube (5) is vertically arranged in the crystallizer (1), the top and bottom of the guide tube (5) are both open-designed, a main shaft (6) is rotatably connected in the crystallizer (1), and the main shaft (6) passes through the bottom end of the guide tube (5) and is connected to a guide blade (7); The main shaft (6) is provided with a reciprocating threaded section at a position between the top end thereof and the guide blade (7), and a nut (8) is meshedly connected to the reciprocating threaded section. A fixed material collector (9) is provided around the inner wall of the top end of the crystallizer (1), and an annular filter screen (10) is connected to the inner ring of the top end of the fixed material collector (9). A connecting rope (11) is connected to the inner ring of the annular filter screen (10) along its radial direction. A vertical groove (51) is vertically provided on the side wall of the guide tube (5) for the connecting rope (11) to pass through. A plurality of sealing blocks (52) are arranged on both sides of the vertical groove (51) from top to bottom. The sealing blocks (52) on both sides pop out and abut against each other. The outer side of the sealing block (52) is designed with an inclined end surface. A plurality of barbs (12) are arranged at intervals on one end of the connecting rope (11) close to the annular filter screen (10). When the nut (8) pulls the connecting rope (11) downward, the barbs (12) enter the guide tube by abutting against the inclined end surface of the sealing block (52). (5), the annular filter screen (10) is pulled by the connecting rope (11) and gradually expands elastically in the direction of its inner circle until the nut (8) moves down to the bottom end of the reciprocating thread section, and the inner circle of the annular filter screen (10) abuts against the outer wall of the guide cylinder (5). As the nut (8) moves upward, the barb (12) abuts against the inner side of the sealing block (52) until the connecting rope (11) passes upward out of the vertical groove (51), and the annular filter screen (10) elastically contracts, and the crystal material on the annular filter screen (10) tilts downward and falls into the fixed collector (9).

2. A continuous crystallization device for para-nitrotoluene according to claim 1, characterized in that: The liquid inlet (3) is located above the outer side of the flow guide tube (5), and the liquid inlet (3) is externally connected to a liquid inlet pipe (31).

3. A continuous crystallization device for para-nitrotoluene according to claim 1, characterized in that: The bottom end of the crystallizer (1) is funnel-shaped, and a transverse partition (13) is connected to the expanded end of the funnel. The transverse partition (13) is hollowed out at a position below and outside the guide tube (5), and the hollowed-out portion is covered with a filter membrane.

4. A continuous crystallization device for para-nitrotoluene according to claim 1, characterized in that: The bottom end of the crystallizer (1) is rotatably connected to a low-speed stirrer (14), and the liquid outlet (4) is located at one side of the bottom end of the crystallizer (1).

5. A continuous crystallization device for p-nitrotoluene according to claim 1, characterized in that: An elastic band (15) is wound around the inner circle of the annular filter screen (10). When the annular filter screen (10) elastically contracts, the elastic band (15) is pulled to extend along the circumferential direction of the inner circle of the annular filter screen (10).

6. A continuous crystallization device for p-nitrotoluene according to claim 5, characterized in that: In the initial state, the width direction of the elastic band (15) is perpendicular to the plane of the annular filter screen (10), and the inner ring of the annular filter screen (10) is connected to the vertical middle position of the elastic band (15).

7. A continuous crystallization device for p-nitrotoluene according to claim 1, characterized in that: A movable collector (16) is provided at the bottom end of the fixed collector (9); a connecting rod (17) is connected to the bottom of the main shaft (6) and is connected to the movable collector (16) through the connecting rod (17) for driving the movable collector (16) to rotate synchronously; the top end of the movable collector (16) is connected to the bottom end of the fixed collector (9); a water filter membrane (18) is obliquely provided at the middle of the movable collector (16); a material leakage port (19) is provided on the side of the movable collector (16) facing the crystallizer (1); a material discharge port (20) is correspondingly provided on the crystallizer (1); the crystal material falls into the movable collector (16) along the fixed collector (9) and is discharged outwardly along the water filter membrane (18), the material leakage port (19) and the material discharge port (20) in sequence.

8. A continuous crystallization device for p-nitrotoluene according to claim 7, characterized in that: The upwardly inclined end of the water filter membrane (18) is connected to a vibration rod (21); a boss (22) is provided on the inner side wall of the fixed collector (9); a convex tooth is provided on the bottom end surface of the boss (22); the bottom of the vibration rod (21) is vertically slidably connected to the movable collector (16); when the movable collector (16) rotates, the top end of the vibration rod (21) slides along the convex tooth and vibrates up and down.

9. A continuous crystallization device for p-nitrotoluene according to claim 7, characterized in that: The side end of the connecting rod (17) is provided with a scraper.

10. A continuous crystallization device for p-nitrotoluene according to claim 1, characterized in that: The guide tube (5) is provided with a magnetic block (23) at the bottom, a collar (81) is sleeved on the outside of the nut (8), a limit pin (82) is inserted horizontally at the side end of the collar (81), a limit hole (83) is correspondingly provided at the side end of the nut (8), a plug pin (84) is vertically inserted at the bottom end of the collar (81), and a plug hole is correspondingly provided on the limit pin (82). When the nut (8) moves down to the bottom end of the reciprocating threaded section, the collar (81) and the plug pin (84) are magnetically attracted by the magnetic block (23), so that the top end of the plug pin (84) moves down out of the plug hole. An elastic telescopic rod (24) is vertically provided at the top end of the inner ring of the annular filter (10), and the elastic telescopic rod (24) is elastically extended. The top of the retracted rod (24) is connected to a pressing sheet (25), one end of which is connected to a pulling rope (26), one end of which is connected to the outer end of a limiting pin (82) and is used to pull the limiting pin (82) outwardly to eject the crystal material above the annular filter screen (10). When the pressing sheet (25) moves downward, the limiting pin (82) moves inwardly and is inserted into the limiting hole (83) to engage the nut (8) with the collar (81). When the nut (8) drives the collar (81) to move upward away from the magnetic block (23), the plug (84) moves upward and is inserted into the insertion hole to keep the nut (8) and the collar (81) in an engaged state.

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