Rectifying tower and rectifying method for urea purification

Abstract

The invention discloses a rectifying tower for urea purification and a rectifying method. The rectifying tower comprises a tower body, a liquid inlet assembly and a heat exchange assembly, the liquid inlet assembly comprises a liquid homogenizing ring pipe arranged in the tower body in a sleeving manner, a liquid inlet spray head arranged on the inner side of the liquid homogenizing ring pipe and a rotating paddle arranged in the tower body; the heat exchange assembly comprises a heat exchange box arranged at the bottom in the tower body and an electric heating sleeve arranged in the heat exchange box; the rectifying tower is reasonable in structural design, a gas-liquid mixture containing NH3 and CO2 discharged by a urea synthesis tower is uniformly dispersed to the upper end of the interior of the tower body, so that NH3 and CO2 in the gas-liquid mixture are separated at a time, then a liquid urea solution is heated and rectified, two-section type rectifying treatment of the urea solution is achieved, and the quality of the urea solution is improved. And the rectification effect of the urea solution is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of urea purification equipment, and in particular to a distillation tower and a distillation method for urea purification. Background Art

[0002] Urea distillation tower is an important equipment used in the urea production process. In the distillation tower, different components in the urea mixture are separated according to their boiling points through heating and cooling, so that high-purity urea can be obtained. The distillation tower plays a vital role in the urea production process and ensures the quality of urea products.

[0003] However, the separation effect of the existing urea distillation tower is poor. When the distillation tower is not working at full load, the amount of steam introduced is small, which will cause the methylamine in the urine to not be fully decomposed, and the high temperature will aggravate the side reaction. At the same time, the existing urea distillation tower heat exchange device is inconvenient to exchange heat with the urea solution at a temperature of 125-132°C when in use, the urea concentration is low, the consumption is increased, and the production capacity of the distillation tower is low. Summary of the invention

[0004] In view of the above-mentioned technical problems, the present invention provides a distillation tower and a distillation method for urea purification.

[0005] The technical solution of the present invention is: a distillation tower for urea purification, comprising a tower body, a liquid inlet assembly arranged at the upper end of the tower body, and a heat exchange assembly arranged at the lower end of the tower body; an exhaust pipe is arranged at the top of the tower body, and a liquid inlet pipe and a liquid discharge pipe are respectively arranged at the upper and lower ends of the outer wall of the tower body;

[0006] The liquid inlet assembly includes a liquid homogenizing ring tube sleeved inside the tower body and communicated with the liquid inlet pipe, a plurality of liquid inlet nozzles equidistantly distributed on the inner side wall of the liquid homogenizing ring tube, and a rotating paddle movably arranged inside the tower body and located inside the liquid homogenizing ring tube; each liquid inlet nozzle is arranged on the inner side wall of the liquid homogenizing ring tube in an inclined direction along the tangent direction of the tower body; a positioning plate is arranged inside the tower body and above the liquid homogenizing ring tube; a through groove is arranged on the positioning plate; the rotating paddle is rotatably clamped on the lower bottom surface of the positioning plate through a rotating shaft; and a through hole is arranged on the rotating paddle;

[0007] The heat exchange assembly includes a heat exchange box arranged at the bottom of the tower body and several electric heating sleeves arranged inside the heat exchange box and arranged mutually. A liquid inlet tank is arranged at the bottom of the heat exchange box, and an air guide pipe is arranged at the top of the heat exchange box. Liquid channels are reserved between the upper and lower ends of each electric heating sleeve and the inner wall of the heat exchange box. A bracket connected to each electric heating sleeve is arranged at the bottom of the heat exchange box.

[0008] Furthermore, an air cap is provided on the positioning plate and above the through groove, and an air hole is provided through the air cap;

[0009] Description: When NH3 and CO2 in the gas-liquid mixture pass through the through-tank, they are discharged through the air holes on the gas cap; the content of urea solution carried by NH3 and CO2 is reduced, thereby effectively reducing the loss of urea solution.

[0010] Furthermore, a barrier mesh plate is arranged inside the through groove, and a crushing cone is arranged on the bottom surface of the barrier mesh plate;

[0011] Note: The gas-liquid mixture contacts the crushing cone during the rising process, which causes the bubbles in the gas-liquid mixture to break, which is beneficial to improving the distillation effect of the urea solution.

[0012] Furthermore, the interior of the positioning plate is hollow, and the top end of the rotating shaft is sleeved with a driving toothed disc clamped in the interior of the positioning plate; the barrier net disc is rotatably clamped in the through groove, and the exterior of the barrier net disc is sleeved with an outer toothed ring meshed with the driving toothed disc; an auxiliary cross bar is arranged on the outer side wall of the crushing cone;

[0013] Note: During the rotation of the shaft, the meshing action of the driving toothed disc and the outer gear ring is utilized to make the barrier mesh disc and the crushing cone rotate simultaneously, which is beneficial to improving the crushing effect of bubbles in the gas-liquid mixture.

[0014] Furthermore, a diverter plate is provided inside the tower body and between the liquid homogenizing ring tube and the heat exchange box; a plurality of diverter cones are provided on the diverter plate and are arranged mutually, and a liquid drop trough is provided on the diverter plate and between two adjacent diverter cones; an air guide pipe runs through the diverter plate, and a conical baffle is provided at the top of the air guide pipe;

[0015] Description: Under the action of the diverter cone, the urea solution falls into the bottom of the tower body through the dropper on the diverter plate, which improves the diffusion uniformity of the urea solution and is beneficial to improving the discharge effect of NH3 and CO2 in the urea solution.

[0016] Furthermore, a surge plate is slidably engaged inside the heat exchange box and sleeved between two adjacent electric heating sleeves, and a linkage rod is provided between the two adjacent surge plates, which penetrates the electric heating sleeves and is slidably engaged with the electric heating sleeves; a number of horizontal axes are scattered and equidistantly distributed inside the tower body, and the ends of each horizontal axis close to each other are connected to winding wheels, and the ends of each horizontal axis far away from each other are connected to bevel gears, and a traction rope connected to the surge plate close to the inner wall of the heat exchange box is wound around each winding wheel; a driving ring is rotatably engaged on the outer wall of the tower body, and a bevel gear ring is provided on the upper end face of the driving ring and is meshed with each bevel gear at the same time, and an inner gear ring is provided on the lower bottom face of the driving ring; a protective sleeve located outside the driving ring is sleeved on the outer wall of the tower body, and a rotating motor is provided inside the protective sleeve, and the output end of the rotating motor is connected to a rotating gear meshed with the inner gear ring;

[0017] Description: The rotating motor is used to drive the rotating gear to rotate. At this time, the driving ring rotates under the meshing action of the inner gear ring and the rotating gear. The meshing action of the bevel gear ring and the bevel gear is used to drive each horizontal axis to rotate on the tower body. During the rotation of the winding wheel, the traction rope is used to pull the surge plate up and down inside the electric heating jacket, so that the urea solution inside the electric heating jacket is heated more evenly, which is beneficial to improve the decomposition efficiency of methylammonium in the urea solution.

[0018] Furthermore, each surge plate is provided with an opening and closing plate at intervals at both ends, and the opening and closing plate is slidably engaged with the surge plate through a guide slide rod, and a return spring abutting against the opening and closing plate is sleeved on the guide slide rod; a counterweight seat is provided on the lower bottom surface of the surge plate inside the inner electric heating sleeve;

[0019] Note: When the surge plate moves upward, the opening and closing plate on the bottom surface of the surge plate opens under the pressure of the urea solution; and when the surge plate moves downward, the opening and closing plate on the upper surface of the surge plate opens, which is beneficial to improve the stirring effect of the surge plate on the urea solution.

[0020] The present invention also provides a distillation method for urea purification, based on the above-mentioned distillation tower for urea purification, comprising the following steps:

[0021] S1. The gas-liquid mixture with a urea concentration of 31-35wt% discharged from the urea synthesis tower is depressurized to 1.5-2.1Mpa and a temperature of 115-118°C, and is introduced into the interior of the liquid homogenizing ring tube through the liquid inlet pipe on the tower body. The gas-liquid mixture is sprayed out through the liquid inlet nozzle and impacts the rotating paddle to rotate, so that the gas-liquid mixture is dispersed more evenly under the action of the rotating paddle;

[0022] S2, NH3 and CO2 in the gas-liquid mixture pass through the barrier mesh on the positioning plate in turn, then escape through the air holes on the gas cap, and finally be discharged through the exhaust pipe. At this time, the remaining substance in the tower body is liquid urea solution; during the rotation of the rotating paddle, the rotating shaft and the driving gear disc are driven to rotate at the same time. At this time, the barrier mesh disc is driven to rotate under the meshing action of the driving gear disc and the outer gear ring, and the bubbles mixed in the gas-liquid mixture are broken by the crushing cone on the bottom surface of the barrier mesh disc;

[0023] S3, the liquid urea solution falls into the bottom of the tower body, and enters the heat exchange box through the liquid inlet tank on the heat exchange box, and the liquid urea solution is heated to 155-160°C by the electric heating jacket, at which time the methylammonium solution in the liquid urea solution undergoes a decomposition reaction to regenerate NH3 and CO2; the regenerated NH3 and CO2 escape through the air guide pipe and are finally discharged through the exhaust pipe;

[0024] S4. After distillation, a urea solution with a urea concentration of 58-65 wt% is obtained, which can be discharged through a drain pipe.

[0025] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0026] First, the distillation tower structure of the present invention is reasonably designed. The gas-liquid mixture containing NH3 and CO2 discharged from the urea synthesis tower is evenly dispersed to the upper end of the tower body, so that NH3 and CO2 in the gas-liquid mixture are separated once, and then the liquid urea solution is heated and distilled, thereby realizing a two-stage distillation treatment of the urea solution and effectively improving the distillation effect of the urea solution.

[0027] Second, the present invention utilizes an electric heating jacket to heat the urea solution, so that the methylamine in the urea solution is further decomposed, which not only increases the concentration of the urea solution, but also helps to reduce the energy consumption of the equipment and increase the production capacity of the equipment;

[0028] Third, the present invention utilizes a surge plate that can move up and down inside the electric heating jacket to extrude and stir the urea solution, so that the heating of the urea solution is more uniform and sufficient, which has a promoting effect on improving the production efficiency of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a longitudinal sectional view of a distillation tower of the present invention;

[0030] Figure 2 is a front view of a distillation tower of the present invention;

[0031] Figure 3 It is a distribution diagram of the liquid inlet nozzle of the present invention on the liquid homogenizing ring tube;

[0032] Figure 4 It is a schematic diagram of the connection between the barrier net disk and the positioning plate of the present invention;

[0033] Figure 5 It is a schematic diagram of the connection between the crushing cone and the barrier mesh disk of the present invention;

[0034] Figure 6 It is a schematic diagram of the connection between the surge plate and the electric heating jacket of the present invention;

[0035] Figure 7 It is a schematic diagram of the connection between the opening and closing plate and the surge plate of the present invention;

[0036] Figure 8 It is a distribution diagram of the horizontal axis of the present invention inside the tower body;

[0037] Fig. 9 The present invention Figure 1 A local enlarged schematic diagram of the middle A;

[0038] Among them, 1-tower body, 10-exhaust pipe, 11-liquid inlet pipe, 12-liquid discharge pipe, 13-cleaning manhole, 2-liquid inlet assembly, 20-liquid uniform ring pipe, 21-liquid inlet nozzle, 22-rotating paddle, 220-rotating shaft, 221-through hole, 222-driving gear disc, 23-positioning plate, 230-through groove, 24-air cap, 240-air hole, 25-barrier mesh disc, 250-crushing cone, 251-outer gear ring, 252-auxiliary cross bar, 3-heat exchange assembly, 30-heat exchange box, 300-liquid inlet tank, 31-electric heating jacket , 310-liquid channel, 311-bracket, 32-air guide tube, 320-conical baffle, 33-surge plate, 330-linkage rod, 331-opening and closing plate, 332-guide slide rod, 333-reset spring, 334-counterweight seat, 34-horizontal axis, 340-winding wheel, 341-bevel gear, 342-traction rope, 35-drive ring, 350-bevel gear ring, 351-inner gear ring, 36-rotating motor, 360-protective cover, 361-rotating gear, 4-diverter plate, 40-diverter cone, 41-liquid drop trough. DETAILED DESCRIPTION

[0039] Example 1

[0040] like Figure 1 , 2 A distillation tower for urea purification shown in the figure comprises a tower body 1, a liquid inlet assembly 2 arranged at the upper end of the tower body 1, and a heat exchange assembly 3 arranged at the lower end of the tower body 1; an exhaust pipe 10 is arranged at the top of the tower body 1, and a liquid inlet pipe 11 and a liquid discharge pipe 12 are respectively arranged at the upper and lower ends of the outer wall of the tower body 1; a cleaning manhole 13 is arranged on the outer wall of the tower body 1;

[0041] like Figure 1 , 3 5, the liquid inlet assembly 2 includes a liquid homogenizing ring tube 20 sleeved inside the tower body 1 and connected to the liquid inlet pipe 11, 12 liquid inlet nozzles 21 equidistantly distributed on the inner wall of the liquid homogenizing ring tube 20, and a rotating paddle 22 movably arranged inside the tower body 1 and located inside the liquid homogenizing ring tube 20; each liquid inlet nozzle 21 is arranged on the inner wall of the liquid homogenizing ring tube 20 in an inclined direction along the tangent direction of the tower body 1; a positioning plate 23 is arranged inside the tower body 1 and above the liquid homogenizing ring tube 20; a through groove 230 is arranged on the positioning plate 23; the rotating paddle 22 is rotatably clamped on the lower bottom surface of the positioning plate 23 through a rotating shaft 220; a through hole 221 is arranged on the rotating paddle 22;

[0042] like Figure 1 , 6As shown, the heat exchange assembly 3 includes a heat exchange box 30 arranged at the bottom of the tower body 1 and two electric heating sleeves 31 arranged inside the heat exchange box 30 and arranged mutually. A liquid inlet tank 300 is arranged at the bottom of the heat exchange box 30, and an air guide pipe 32 is arranged at the top of the heat exchange box 30. Liquid channels 310 are reserved between the upper and lower ends of each electric heating sleeve 31 and the inner wall of the heat exchange box 30. A bracket 311 connected to each electric heating sleeve 31 is arranged at the bottom of the heat exchange box 30.

[0043] Example 2

[0044] This embodiment describes a distillation method for urea purification, based on a distillation tower for urea purification in Example 1, comprising the following steps:

[0045] S1. The gas-liquid mixture with a urea concentration of 31 wt% discharged from the urea synthesis tower is depressurized to 1.5 MPa and a temperature of 115° C. The mixture is introduced into the liquid homogenizing ring tube 20 through the liquid inlet pipe 11 on the tower body 1. The gas-liquid mixture is sprayed out through the liquid inlet nozzle 21 and impacts the rotating paddle 22 to rotate, so that the gas-liquid mixture is dispersed more evenly under the action of the rotating paddle 22;

[0046] S2, NH3 and CO2 in the gas-liquid mixture pass through the through groove 230 on the positioning plate 23 in sequence and are discharged through the exhaust pipe 10; at this time, the remaining substance inside the tower body 1 is liquid urea solution;

[0047] S3, the liquid urea solution falls into the bottom of the tower body 1, and enters the heat exchange box 30 through the liquid inlet tank 300 on the heat exchange box 30, and the liquid urea solution is heated to 155° C. by the electric heating jacket 31, at which time the methylammonium solution in the liquid urea solution undergoes a decomposition reaction to regenerate NH3 and CO2; the regenerated NH3 and CO2 escape through the air guide pipe 32, and are finally discharged through the exhaust pipe 10;

[0048] S4. After distillation, a urea solution with a urea concentration of 58 wt% is obtained, which can be discharged through the drain pipe 12.

[0049] Example 2

[0050] The difference between this embodiment and the first embodiment is that 15 liquid inlet nozzles 21 are provided and 4 electric heating jackets 31 are provided.

[0051] Example 3

[0052] The difference between this embodiment and embodiment 1 is that:

[0053] like Figure 1 , 4As shown in Figure 5, an air cap 24 is provided on the positioning plate 23 and above the through groove 230, and an air hole 240 is penetrated on the air cap 24; a blocking mesh disk 25 is provided inside the through groove 230, and a crushing cone 250 is provided on the lower bottom surface of the blocking mesh disk 25; the interior of the positioning plate 23 is hollow, and the top end of the rotating shaft 220 is provided with a driving toothed disk 222 that is clamped in the interior of the positioning plate 23; the blocking mesh disk 25 is rotatably clamped in the through groove 230, and the outside of the blocking mesh disk 25 is provided with an outer gear ring 251 that is meshed and connected to the driving toothed disk 222; an auxiliary cross bar 252 is provided on the outer wall of the crushing cone 250.

[0054] Example 4

[0055] The difference between this embodiment and embodiment 3 is that:

[0056] like Figure 1 As shown, a diverter plate 4 is provided inside the tower body 1 and between the liquid homogenizing ring tube 20 and the heat exchange box 30; three diverter cones 40 which are nested with each other are provided on the diverter plate 4, and a liquid drop trough 41 is provided on the diverter plate 4 and between two adjacent diverter cones 40; an air guide pipe 32 passes through the diverter plate 4, and a conical baffle plate 320 is provided at the top of the air guide pipe 32.

[0057] Example 5

[0058] The difference between this embodiment and embodiment 4 is that:

[0059] like Figure 1 , 6 As shown in Figures 7 and 9, a surge plate 33 is slidably engaged inside the heat exchange box 30 and is sleeved between two adjacent electric heating sleeves 31. A linkage rod 330 is provided between the two adjacent surge plates 33 and penetrates the electric heating sleeves 31 and is slidably engaged with the electric heating sleeves 31. Four horizontal axes 34 are evenly distributed in a scattered manner inside the tower body 1. The ends of the horizontal axes 34 that are close to each other are connected to a winding wheel 340, and the ends of the horizontal axes 34 that are far away from each other are connected to a bevel gear 341. Each winding wheel 340 is wound with a gear that is close to the heat exchanger. A traction rope 342 is connected to the surge plate 33 on the inner wall of the heat box 30; a drive ring 35 is rotatably clamped on the outer wall of the tower body 1, and a bevel gear ring 350 is provided on the upper end surface of the drive ring 35 to mesh with each bevel gear 341 at the same time, and an inner gear ring 351 is provided on the lower bottom surface of the drive ring 35; a protective sleeve 360 ​​is provided on the outer wall of the tower body 1 and is located outside the drive ring 35, and a rotating motor 36 is provided inside the protective sleeve 360, and the output end of the rotating motor 36 is connected to a rotating gear 361 meshing with the inner gear ring 351.

[0060] Example 6

[0061] The difference between this embodiment and embodiment 5 is that:

[0062] like Figure 6, 7 As shown, opening and closing plates 331 are arranged at intervals at the upper and lower ends of each surge plate 33, and the opening and closing plates 331 are slidably engaged with the surge plates 33 through guide slide bars 332, and a return spring 333 abutting against the opening and closing plates 331 is sleeved on the guide slide bars 332; a counterweight seat 334 is arranged on the lower bottom surface of the surge plate 33 inside the inner electric heating sleeve 31.

[0063] Example 7

[0064] This embodiment describes a distillation method for urea purification, based on a distillation tower for urea purification in Example 6, comprising the following steps:

[0065] S1. The gas-liquid mixture with a urea concentration of 35 wt% discharged from the urea synthesis tower is depressurized to 2.1 MPa and a temperature of 118° C. The mixture is introduced into the liquid homogenizing ring tube 20 through the liquid inlet pipe 11 on the tower body 1. The gas-liquid mixture is sprayed out through the liquid inlet nozzle 21 and impacts the rotating paddle 22 to rotate, so that the gas-liquid mixture is dispersed more evenly under the action of the rotating paddle 22;

[0066] S2, NH3 and CO2 in the gas-liquid mixture successively pass through the barrier mesh disk 25 on the positioning plate 23 and then escape through the air hole 240 on the gas cap 24, and are finally discharged through the exhaust pipe 10; at this time, the remaining substance inside the tower body 1 is a liquid urea solution; during the rotation of the rotating paddle 22, the rotating shaft 220 and the driving gear disk 222 are driven to rotate at the same time, and at this time, the barrier mesh disk 25 is driven to rotate under the meshing action of the driving gear disk 222 and the outer gear ring 251, and the bubbles mixed in the gas-liquid mixture are broken by the crushing cone 250 on the bottom surface of the barrier mesh disk 25;

[0067] S3, the urea solution falls into the bottom of the tower body 1 through the liquid drop groove 41 on the diverter plate 4 under the action of the diverter cone 40, and enters the heat exchange box 30 through the liquid inlet groove 300 on the heat exchange box 30, and the liquid urea solution is heated to 160 ° C by the electric heating jacket 31. At this time, the methylammonium solution in the liquid urea solution undergoes a decomposition reaction to regenerate NH3 and CO2; the regenerated NH3 and CO2 escape through the air guide pipe 32 and are finally discharged through the exhaust pipe 10; during the heating process of the urea solution, the rotating motor 36 is used to drive the rotating gear 361 to rotate, and the driving ring 35 rotates under the meshing action of the inner gear ring 351 and the rotating gear 361, and the meshing action of the bevel gear ring 350 and the bevel gear 341 drives each horizontal shaft 34 to rotate on the tower body 1. During the rotation of the winding wheel 340, the traction rope 342 is used to pull the surge plate 33 up and down inside the electric heating sleeve 31. During the upward movement of the surge plate 33, the opening and closing plate 331 on the bottom surface of the surge plate 33 is opened under the pressure of the urea solution; and during the downward movement of the surge plate 33, the opening and closing plate 331 on the upper end surface of the surge plate 33 is opened, so that the urea solution is heated more evenly;

[0068] S4. After distillation, a urea solution with a urea concentration of 65 wt% is obtained, which can be discharged through the drain pipe 12.

[0069] It should be noted that the liquid inlet nozzle 21, electric heating jacket 31 and rotating motor 36 used in the present invention all adopt existing technologies, and are not specifically limited here. Those skilled in the art can select corresponding products according to actual needs.

Claims

1. A distillation tower for urea purification, characterized in that: It comprises a tower body (1), a liquid inlet assembly (2) arranged at the upper end of the tower body (1), and a heat exchange assembly (3) arranged at the lower end of the tower body (1); an exhaust pipe (10) is arranged at the top of the tower body (1), and a liquid inlet pipe (11) and a liquid discharge pipe (12) are respectively arranged at the upper and lower ends of the outer wall of the tower body (1); The liquid inlet assembly (2) comprises a liquid homogenizing ring tube (20) sleeved inside the tower body (1) and connected to the liquid inlet tube (11), a plurality of liquid inlet nozzles (21) equidistantly distributed on the inner side wall of the liquid homogenizing ring tube (20), and a rotating paddle (22) movably arranged inside the tower body (1) and located inside the liquid homogenizing ring tube (20); each of the liquid inlet nozzles (21) is arranged on the inner side wall of the liquid homogenizing ring tube (20) at an angle along the tangent direction of the tower body (1); a positioning plate (23) is arranged inside the tower body (1) and above the liquid homogenizing ring tube (20); a through groove (230) is arranged on the positioning plate (23); the rotating paddle (22) is rotatably clamped on the lower bottom surface of the positioning plate (23) via a rotating shaft (220); and a through hole (221) is arranged on the rotating paddle (22); The heat exchange assembly (3) comprises a heat exchange box (30) arranged at the bottom of the tower body (1) and a plurality of electric heating sleeves (31) arranged inside the heat exchange box (30) and arranged one inside the other; a liquid inlet tank (300) is arranged at the bottom of the heat exchange box (30), and an air guide pipe (32) is arranged at the top of the heat exchange box (30); a liquid channel (310) is reserved between the upper and lower ends of each of the electric heating sleeves (31) and the inner wall of the heat exchange box (30); and a bracket (311) connected to each of the electric heating sleeves (31) is arranged at the bottom of the heat exchange box (30).

2. A distillation tower for urea purification according to claim 1, characterized in that: An air cap (24) is provided on the positioning plate (23) and above the through groove (230), and an air hole (240) is provided through the air cap (24).

3. A distillation tower for urea purification according to claim 2, characterized in that: A barrier mesh plate (25) is arranged inside the through groove (230), and a crushing cone (250) is arranged on the lower surface of the barrier mesh plate (25).

4. A distillation tower for urea purification according to claim 3, characterized in that: The interior of the positioning plate (23) is hollow, and the top end of the rotating shaft (220) is sleeved with a driving toothed disc (222) that is clamped in the interior of the positioning plate (23); the blocking mesh disc (25) is rotatably clamped in the interior of the through groove (230), and the outside of the blocking mesh disc (25) is sleeved with an outer toothed ring (251) that is meshed and connected with the driving toothed disc (222); and an auxiliary cross bar (252) is provided on the outer side wall of the crushing cone (250).

5. A distillation tower for urea purification according to claim 1, characterized in that: A flow divider plate (4) is arranged inside the tower body (1) and between the liquid homogenizing ring tube (20) and the heat exchange box (30); a plurality of mutually nested flow divider cones (40) are arranged on the flow divider plate (4); a liquid drop trough (41) is arranged on the flow divider plate (4) and between two adjacent flow divider cones (40); the air guide pipe (32) passes through the flow divider plate (4), and a conical baffle plate (320) is arranged at the top end of the air guide pipe (32).

6. A distillation tower for urea purification according to claim 1, characterized in that: The heat exchange box (30) is internally slidably engaged with a surge plate (33) sleeved between two adjacent electric heating sleeves (31), and a linkage rod (330) penetrating the electric heating sleeve (31) and slidably engaged with the electric heating sleeve (31) is provided between the two adjacent surge plates (33); a plurality of horizontal axes (34) are evenly distributed in a scattered manner inside the tower body (1), and the ends of the horizontal axes (34) close to each other are connected to a winding wheel (340), and the ends of the horizontal axes (34) far away from each other are connected to a bevel gear (341), and each winding wheel (340) is wound with a gear wheel (341) close to the inner wall of the heat exchange box (30). A traction rope (342) connected to a surge plate (33) is provided; a drive ring (35) is rotatably connected to the outer wall of the tower body (1); a bevel gear ring (350) meshingly connected to each of the bevel gears (341) is provided on the upper end surface of the drive ring (35); an inner gear ring (351) is provided on the lower bottom surface of the drive ring (35); a protective sleeve (360) located outside the drive ring (35) is sleeved on the outer wall of the tower body (1); a rotating motor (36) is provided inside the protective sleeve (360); an output end of the rotating motor (36) is connected to a rotating gear (361) meshingly connected to the inner gear ring (351).

7. A distillation tower for urea purification according to claim 6, characterized in that: An opening and closing plate (331) is arranged at intervals at both upper and lower ends of each surge plate (33); the opening and closing plate (331) is slidably engaged with the surge plate (33) via a guide slide bar (332); a return spring (333) abutting against the opening and closing plate (331) is sleeved on the guide slide bar (332); a counterweight seat (334) is arranged on the lower bottom surface of the surge plate (33) inside the inner electric heating sleeve (31).

8. A distillation method for urea purification, based on the distillation tower for urea purification according to claim 4, characterized in that: The following steps are involved: S1. The gas-liquid mixture with a urea concentration of 31 to 35 wt% discharged from the urea synthesis tower is depressurized to 1.5 to 2.1 MPa and a temperature of 115 to 118° C., and is introduced into the interior of the liquid homogenizing ring tube (20) through the liquid inlet pipe (11) on the tower body (1). The gas-liquid mixture is sprayed out through the liquid inlet nozzle (21) and impacts the rotating paddle (22) to cause it to rotate, so that the gas-liquid mixture is dispersed more evenly under the action of the rotating paddle (22); S2, NH3 and CO2 in the gas-liquid mixture sequentially pass through the barrier mesh disk (25) on the positioning plate (23) and then escape through the air holes (240) on the gas cap (24), and are finally discharged through the exhaust pipe (10). At this time, the remaining substance in the tower body (1) is a liquid urea solution; during the rotation of the rotating paddle (22), the rotating shaft (220) and the driving gear disk (222) are driven to rotate simultaneously. At this time, the barrier mesh disk (25) is driven to rotate under the meshing action of the driving gear disk (222) and the outer gear ring (251), and the bubbles mixed in the gas-liquid mixture are crushed by the crushing cone (250) on the bottom surface of the barrier mesh disk (25); S3, the liquid urea solution falls into the bottom of the tower body (1), and enters the interior of the heat exchange box (30) through the liquid inlet tank (300) on the heat exchange box (30), and the liquid urea solution is heated to 155-160° C. by the electric heating jacket (31), at which time the methylammonium solution in the liquid urea solution undergoes a decomposition reaction to regenerate NH3 and CO2; the regenerated NH3 and CO2 escape through the air guide pipe (32), and are finally discharged through the exhaust pipe (10); S4. After distillation, a urea solution with a urea concentration of 58-65 wt% is obtained, which can be discharged through the drain pipe (12).

9. A distillation tower for urea purification according to claim 1, characterized in that: An air cap (24) is provided on the positioning plate (23), and an air hole (240) is provided through the air cap (24).

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