Cooling device for urea production

Abstract

The cooling device for urea production comprises a granulation tower, an air inlet window is formed in the side wall of a tower body of the granulation tower, and the bottom of the tower body of the granulation tower communicates with a cold air bin through a connecting cylinder; a first heat exchange coil pipe is arranged in the cold air bin, and an air inlet connected with a first fan is formed in one side face of the cold air bin. According to the device, the air window is formed in the side wall of the granulation tower, granulated urea particles are primarily cooled through air blown in from the outside, meanwhile, the cold air bin provided with the first heat exchange coil pipe is arranged at the bottom of the granulation tower, and a cooling medium is introduced into the first heat exchange coil pipe; the air blown in by the first fan is subjected to heat exchange and cooled and then is used for cooling the urea particles again, so that the problem that the urea particles are hardened and the product quality is influenced due to insufficient cooling of the urea particles granulated by the granulation device in a spray granulation mode is solved.

Description

Technical Field

[0001] The present application relates to the technical field of urea production, and in particular to a cooling device for urea production. Background Art

[0002] Urea is an organic compound composed of carbon, nitrogen, oxygen and hydrogen. It is also called urea. It is a white crystal and one of the simplest organic compounds. It is also the nitrogen fertilizer with the highest nitrogen content. As a neutral fertilizer, urea is suitable for various soils and plants. It is easy to store, convenient to use, and has little destructive effect on the soil. It is currently a chemical nitrogen fertilizer with a large usage. In industry, urea is synthesized with ammonia and carbon dioxide under certain conditions, and granulated into suitable particles before it can be output as a qualified product.

[0003] During granulation production, urea is prepared into a solution containing about 96.5% urea by mass, and sprayed through a granulation device at a temperature of 132°C for granulation. After being sprayed into droplets, the urea solution is cooled and condensed into urea particles during the falling process. The temperature of these newly formed urea particles is about 100°C. If the cooling is insufficient, these urea particles will agglomerate into large pieces, resulting in a decrease in product quality, which is particularly harmful to small-particle urea. Therefore, it is necessary to fully cool the granulated urea particles in the granulation device to prevent them from becoming hardened due to excessive temperature, which affects product quality. Utility Model Content

[0004] The present application provides a cooling device for urea production, which is used to solve the problem that in a spray granulation method, urea granules granulated by a granulation device are not sufficiently cooled, resulting in urea granules becoming hardened, thereby affecting product quality.

[0005] The present application provides a cooling device for urea production, comprising a granulation tower, wherein a granulation nozzle and a perforated plate are sequentially arranged on the top of the tower body of the granulation tower from top to bottom;

[0006] The orifice plate is arranged in a tower body of the granulation tower at a certain angle, and a discharge port is opened on the side wall of the tower body of the granulation tower, the discharge port is close to the lower end of the orifice plate on the vertical plane, and the discharge port is located above the orifice plate;

[0007] At least one air inlet window is provided on the side wall of the tower body of the granulation tower, and the air inlet window is located between the granulation nozzle and the orifice plate;

[0008] The bottom of the granulation tower is connected to the cold air bin through a connecting tube; a discharge port is provided at the bottom of the cold air bin;

[0009] A first heat exchange coil is arranged in the cold air bin, and an air inlet is arranged on one side of the cold air bin, the air inlet is arranged between the first heat exchange coil and the discharge port; the air inlet is connected to the first fan.

[0010] Optionally, a dust filter cover is provided on the top of the tower body of the granulation tower, and the granulation nozzle passes through the dust filter cover and extends into the tower body of the granulation tower;

[0011] The dust filter cover is also connected with the dust removal device.

[0012] Optionally, the granulation nozzle is connected to the second fan and the feeder respectively through a mixing bin.

[0013] Optionally, the discharge port is connected to the transfer bed;

[0014] The transmission bed comprises a transmission bed surface, a second heat exchange coil is fixedly arranged on the lower surface of the transmission bed surface, a vibration layer is connected below the transmission bed surface, and a vibrator is installed on the vibration layer;

[0015] The vibration layer is supported by a shock-absorbing structure;

[0016] The cooling medium output end of the second heat exchange coil is connected to the cooling medium input end of the first heat exchange coil.

[0017] Optionally, the dust removal device includes a cyclone dust collector, a third fan, a bag dust collector and a water washing tower which are connected in series in sequence.

[0018] Optionally, an axial flow fan is arranged in the air inlet window.

[0019] Optionally, a demister is provided in the connecting cylinder.

[0020] The present application provides a cooling device for urea production, which uses air blown in from the outside to perform primary cooling on granulated urea particles by opening a wind window on the side wall of a granulation tower, and at the same time, a cold air bin with a first heat exchange coil is arranged at the bottom of the granulation tower, and a cooling medium is introduced into the first heat exchange coil, and the air blown in by the first fan is used again to cool the urea particles after heat exchange and cooling. The device of the present application can reduce the temperature of high-temperature urea particles after granulation through the coordinated use of the above-mentioned devices, effectively prevent urea from agglomerating due to high temperature, and overcome the problem that in a spray granulation method, the urea particles granulated by the granulation device are agglomerated due to insufficient cooling, thereby affecting the product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of a cooling device for urea production provided in one embodiment of the present application;

[0023] Figure 2 A schematic diagram of a cooling device for urea production provided in another embodiment of the present application;

[0024] Figure 3 A schematic diagram of a cooling device for urea production provided in another embodiment of the present application;

[0025] Figure 4 A schematic diagram of a dust removal device provided in one embodiment of the present application;

[0026] Figure 5 A schematic diagram of a cooling device for urea production provided in yet another embodiment of the present application.

[0027] Description of reference numerals:

[0028] 1. Granulation tower; 2. Dust removal device; 3. Conveyor bed; 10. Mixing bin; 11. Granulation nozzle; 12. Orifice plate; 13. Air inlet window; 14. Connecting tube; 15. Cold air bin; 16. Dust filter cover; 17. Second fan; 18. Feeder; 21. Cyclone dust collector; 22. Third fan; 23. Bag filter; 24. Washing tower; 31. Conveyor bed surface; 32. Second heat exchange coil; 33. Vibration layer; 34. Shock absorption structure; 101. Discharge port; 131. Axial flow fan; 141. Demister; 151. First heat exchange coil; 152. First fan; 331. Vibrator; 1501. Discharge port; 1502. Air inlet. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0030] like Figure 1 As shown, the present application provides a cooling device for urea production, comprising a granulation tower 1, wherein a granulation nozzle 11 and a perforated plate 12 are sequentially arranged in the top of the tower body of the granulation tower 1 from top to bottom;

[0031] The orifice plate 12 is arranged in a certain angle in the tower body of the granulation tower 1, and a discharge port 101 is opened on the side wall of the tower body of the granulation tower 1. The discharge port 101 is close to the lower end of the orifice plate 12 on the vertical plane, and the discharge port 101 is located above the orifice plate 12;

[0032] At least one air inlet window 13 is provided on the side wall of the granulation tower 1, and the air inlet window 13 is located between the granulation nozzle 11 and the orifice plate 12;

[0033] The bottom of the tower body of the granulation tower 1 is connected to the cold air bin 15 through the connecting tube 14; the bottom of the cold air bin 15 is provided with a discharge port 1501;

[0034] A first heat exchange coil 151 is disposed in the cold air bin 15 , and an air inlet 1502 is provided on one side of the cold air bin 15 . The air inlet 1502 is disposed between the first heat exchange coil 151 and the discharge port 1501 ; the air inlet 1502 is connected to the first fan 152 .

[0035] In the present application, the connecting tube 14 can be a straight tube structure or a Figure 1 The laryngeal structure shown in .

[0036] When in use, the granulation nozzle 11 sprays high-temperature urea solution, and the sprayed urea droplets condense into spherical particles due to the decrease in temperature and fall down. At this time, the outside air enters the tower (a filter can be set on the air inlet window 13 to prevent the outside dust from entering the tower and affecting the purity of the product), and the wind blown into the tower from the wind window 13 performs preliminary heat exchange cooling on the falling urea particles. The wind after heat exchange moves to the top of the tower and is discharged after being processed.

[0037] The urea particles initially cooled by the wind blown in through the wind window 13 continue to fall. At the same time, the first fan 152 is turned on, and a cooling medium (such as circulating cooling water) is introduced into the first heat exchange coil 151. At this time, the air (which has been purified) blown in by the first fan 152 is cooled down after heat exchange through the first heat exchange coil 151, and the temperature is reduced. After cooling, cold wind is formed, and the cold wind is blown upward from the holes on the orifice plate 12 (the size of the holes on the orifice plate 12 can be slightly smaller than the urea particles) after passing through the connecting tube 14. The blown cold wind contacts the falling urea particles, so that the urea particles are in a fluidized state (the leakage of urea particles from the orifice plate 12 can be reduced), and the urea particles are further cooled. After heat exchange with the urea particles, the cold wind moves upward (a part of it will be blown out from the discharge port 101. In order to prevent the cold wind from blowing out the urea particles, a baffle can be added at the discharge port 101 to prevent this phenomenon from happening), and is combined with the air blown in by the wind window 13, and then filtered through the filtering device and discharged from the top of the tower.

[0038] Since the orifice plate 12 is inclined, the urea particles in the fluidized state will gradually move toward the discharge port 101, and finally be discharged through the discharge port 101, received by the corresponding container, and input into the subsequent processing section for subpackaging, packaging and other operations.

[0039] Since there are small holes on the orifice plate 12, it is inevitable that some urea particles will fall into the cold air bin 15 through the small holes during use. These urea particles falling into the cold air bin 15 are gathered in the cold air bin 15 and discharged through the discharge port 1501. They are recovered for preparing urea solution and used for granulation again.

[0040] The present application provides a cooling device for urea production, which uses air blown in from the outside to perform primary cooling on granulated urea particles by opening a wind window 13 on the side wall of a granulation tower 1, and at the same time, a cold air bin 15 with a first heat exchange coil 151 is arranged at the bottom of the granulation tower 1, and a cooling medium is introduced into the first heat exchange coil 151, and the air blown in by a first fan 152 is used again to cool the urea particles after heat exchange and cooling. The device of the present application can reduce the temperature of high-temperature urea particles after granulation through the coordinated use of the above-mentioned equipment, effectively prevent urea from agglomerating due to high temperature, and overcome the problem that in the spray granulation method, the urea particles granulated by the granulation device are agglomerated due to insufficient cooling, thereby affecting the product quality.

[0041] like Figure 1 and Figure 2 As shown, optionally, a dust filter cover 16 is provided on the top of the tower body of the granulation tower 1, and the granulation nozzle 11 passes through the dust filter cover 16 and extends into the tower body of the granulation tower 1;

[0042] The dust filter cover 16 is also connected to the dust removal device 2.

[0043] In the present application, since the urea granules are granulated by spraying, it is inevitable that tiny droplets will condense into urea granules. These urea granules are small in size and light in weight, and are easily entrained by the upward cold wind. If they are discharged without treatment, it will not only cause product loss but also cause environmental pollution. Therefore, a dust filter hood 16 is provided to intercept the urea particles in the discharged air to reduce waste.

[0044] like Figure 2 As shown, optionally, the granulation nozzle 11 is connected to the second fan 17 and the feeder 18 respectively through the mixing bin 10.

[0045] When in use, the second fan 17 draws in external air (the air is filtered and purified) and mixes it with the urea solution (mass fraction ≥ 96.5%, temperature greater than 132°C) in the feeder 18 in the mixing chamber 10 to form a gas-liquid mixture. The gas-liquid mixture enters the granulation nozzle 11 through a pipeline and is sprayed out for granulation.

[0046] like Figure 3 As shown, optionally, the discharge port 101 is connected to the transport bed 3;

[0047] The transmission bed 3 comprises a transmission bed surface 31, a second heat exchange coil 32 is fixedly arranged on the lower surface of the transmission bed surface 31, a vibration layer 33 is connected below the transmission bed surface 31, and a vibrator 331 is installed on the vibration layer 33;

[0048] The vibration layer 33 is supported by a shock absorbing structure 34;

[0049] The cooling medium output end of the second heat exchange coil 32 is connected to the cooling medium input end of the first heat exchange coil 151 .

[0050] When in use, it is discharged through the discharge port 101 to the transfer bed 3 and transferred to the discharge end.

[0051] At this time, the vibrator 331 fixed on the vibration layer is started, and the urea particles falling on the transmission bed 3 will bounce on the transmission bed surface 31 (a flat plate made of stainless steel in this application) under the reciprocating vibration of the vibrator 331. If there are agglomerated urea particles, the agglomerated urea particles will be broken up by hitting the transmission bed surface 31 during the jumping process. At the same time, the circulating cooling water introduced into the second heat exchange coil 32 exchanges heat and cools the transmission bed surface 31, cooling the urea particles again. In practice, in order to speed up the transmission speed, the transmission bed surface 31 can be set to an inclined plane with a certain inclination angle, and the inclination direction is from the discharge port 101 to the transmission bed surface. The inclination angle should not be too large, preferably less than 1.5°. The urea particles transmitted through the transmission bed surface 31 are received by the corresponding container at the output end, and are input into the subsequent processing section for subpackaging, packaging and other operations.

[0052] The shock absorbing structure 34 is a structure having a buffering capability, such as a spring.

[0053] In the present application, the cooling medium output end of the second heat exchange coil 32 is connected to the cooling medium input end of the first heat exchange coil 151, which can fully utilize the cooling capacity provided by the cooling medium and reduce energy waste.

[0054] like Figure 4 As shown, optionally, the dust removal device 2 includes a cyclone dust collector 21, a third fan 22, a bag dust collector 23 and a water washing tower 24 which are connected in series in sequence.

[0055] In the present application, when in use, the exhaust gas filtered by the dust filter hood 16 at the top of the granulation tower 1 enters the dust removal device 2 for dust removal and purification. Since a small amount of urea dust is still entrained therein, most of the urea dust is intercepted and recovered by the dry dust removal method of the cyclone dust collector 21 and the bag dust collector 23 in turn, wherein the third fan 22 is used to accelerate the exhaust gas to improve the dust removal efficiency of the exhaust gas in the cyclone dust collector 21. The exhaust gas after dust removal by the cyclone dust collector 21 and the bag dust collector 23 enters the water washing tower 24 for washing, and the residual urea dust in the exhaust gas is washed and removed before being discharged.

[0056] like Figure 5 As shown, optionally, an axial flow fan 131 is provided in the air inlet window 13 .

[0057] In the present application, an axial flow fan 131 is arranged in the air inlet window 13, and the axial flow fan 131 can be used to strengthen the outside air entering the tower, thereby improving the heat exchange efficiency of the urea particles in the tower.

[0058] like Figure 5 As shown, optionally, a demister 141 is provided in the connecting tube 14 .

[0059] In this application, when the external humidity is high, the moisture in the air will condense into droplets after the air passes through the first heat exchange coil 151 for heat exchange. If not treated, the urea particles will melt and harden after contacting with the urea particles, resulting in reduced urea quality. Therefore, a defogger 141 is provided to remove the condensed water mist in the air. In this application, a defogger with a small pressure drop, such as a baffle defogger, is selected. In a feasible manner, the air can also be dehumidified and then blown into the cold air bin 15 through the first fan 152.

[0060] A cooling device for urea production, the use process of which is as follows:

[0061] When in use, the second fan 17 sucks the outside air (the air is filtered and purified) and mixes it with the urea solution (mass fraction ≥ 96.5%, temperature greater than 132°C) in the feeder 18 in the mixing bin 10 to form a gas-liquid mixture. These gas-liquid mixtures enter the granulation nozzle 11 through the pipeline and are sprayed out. The sprayed urea droplets condense into spherical particles and fall down due to the temperature reduction. At this time, the axial flow fan 131 in the air inlet window 13 is started to blow the outside air into the tower (a filter screen can be set on the air inlet window 13 to prevent the outside dust from entering the tower and affecting the product purity). The wind blown into the tower from the wind window 13 performs preliminary heat exchange cooling on the falling urea particles. The wind after heat exchange moves to the top of the tower, and the dust filter cover 16 at the top of the tower filters the dust therein and outputs it to the dust removal device 2.

[0062] The urea particles initially cooled by the wind blown in through the wind window 13 continue to fall. At the same time, the first fan 152 is turned on, and a cooling medium (such as circulating cooling water) is introduced into the second heat exchange coil 32. The cooling water enters the first heat exchange coil 151 after passing through the second heat exchange coil 32. At this time, the air (which has been purified) blown in by the first fan 152 is cooled by the first heat exchange coil 151 after heat exchange. The cooled air passes through the defogger 141 (when the outside humidity is high, the moisture in the air will condense into droplets after the air passes through the first heat exchange coil 151. If it is not treated, the urea particles will melt and harden after contacting with the urea particles. ) intercepts the droplets in the air and improves the dryness of the air. The defogged air passes through the connecting tube 14 and is blown upward from the holes on the orifice plate 12 (the size of the holes on the orifice plate 12 can be slightly smaller than the urea particles). The blown cold air contacts the falling urea particles to make the urea particles fluidized (the leakage of urea particles from the orifice plate 12 can be reduced), and the urea particles are further cooled. The cold air exchanges heat with the urea particles and moves upward (a part of it will be blown out from the discharge port 101. In order to prevent the cold air from blowing out the urea particles, a baffle can be added at the discharge port 101 to prevent this from happening). It is combined with the air blown in from the wind window 13, filtered through the dust filter hood 16, and then discharged from the top of the tower.

[0063] Since the orifice plate 12 is arranged obliquely, the urea particles in the fluidized state will gradually move toward the discharge port 101 , and finally be discharged through the discharge port 101 to the transport bed 3 and transported toward the discharge end.

[0064] At this time, the vibrator 331 fixed on the vibration layer is started, and the urea particles falling on the transmission bed 3 will bounce on the transmission bed surface 31 (a flat plate made of stainless steel in this application) under the reciprocating vibration of the vibrator 331. If there are agglomerated urea particles, the agglomerated urea particles will be broken up by hitting the transmission bed surface 31 during the jumping process. At the same time, the circulating cooling water introduced into the second heat exchange coil 32 exchanges heat and cools the transmission bed surface 31, cooling the urea particles again. In practice, in order to speed up the transmission speed, the transmission bed surface 31 can be set to an inclined plane with a certain inclination angle, and the inclination direction is from the discharge port 101 to the transmission bed surface. The inclination angle should not be too large, preferably less than 1.5°. The urea particles transmitted through the transmission bed surface 31 are received by the corresponding container at the output end, and are input into the subsequent processing section for subpackaging, packaging and other operations.

[0065] The exhaust gas filtered by the dust filter 16 on the top of the granulation tower 1 enters the dust removal device 2 for dust removal and purification. Since a small amount of urea dust is still entrained therein, most of the urea dust is intercepted and recovered by the dry dust removal method of the cyclone dust collector 21 and the bag dust collector 23 in turn. The third fan 22 is used to accelerate the exhaust gas to improve the dust removal efficiency of the exhaust gas in the cyclone dust collector 21. The exhaust gas after dust removal by the cyclone dust collector 21 and the bag dust collector 23 enters the water washing tower 24 for washing, and the residual urea dust in the exhaust gas is washed and removed before being discharged.

[0066] Since the orifice plate 12 has small holes, it is inevitable that some urea particles will fall into the cold air bin 15 through the small holes during use. These urea particles falling into the cold air bin 15 are gathered in the cold air bin 15 and then discharged through the discharge port 1501.

[0067] The urea particles recovered after dust removal by the cyclone dust collector 21 and the bag dust collector 23, as well as the washing water after washing in the water washing tower 24 and the urea particles in the cold air bin 15 can be recovered for preparing urea solution and used again for granulation.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A cooling device for urea production, comprising a granulation tower (1), characterized in that: The top of the tower body of the granulation tower (1) is provided with a granulation nozzle (11) and a perforated plate (12) in sequence from top to bottom; The orifice plate (12) is arranged in a tower body of the granulation tower (1) at a certain angle, and a discharge port (101) is provided on the side wall of the tower body of the granulation tower (1), the discharge port (101) is close to the lower end of the orifice plate (12) on the vertical plane, and the discharge port (101) is located above the orifice plate (12); At least one air inlet window (13) is provided on the side wall of the tower body of the granulation tower (1), and the air inlet window (13) is located between the granulation nozzle (11) and the orifice plate (12); The bottom of the tower body of the granulation tower (1) is connected to the cold air bin (15) via a connecting tube (14); a discharge port (1501) is provided at the bottom of the cold air bin (15); A first heat exchange coil (151) is arranged in the cold air bin (15), and an air inlet (1502) is provided on one side of the cold air bin (15), wherein the air inlet (1502) is arranged between the first heat exchange coil (151) and the discharge port (1501); the air inlet (1502) is connected to a first fan (152).

2. The cooling device for urea production according to claim 1, characterized in that: A dust filter cover (16) is arranged on the top of the tower body of the granulation tower (1), and the granulation nozzle (11) passes through the dust filter cover (16) and extends into the tower body of the granulation tower (1); The dust filter cover (16) is also connected to the dust removal device (2).

3. The cooling device for urea production according to claim 1, characterized in that: The granulation nozzle (11) is connected to the second fan (17) and the feeder (18) respectively through the mixing bin (10).

4. The cooling device for urea production according to claim 1, characterized in that: The discharge port (101) is connected to the transmission bed (3); The transmission bed (3) comprises a transmission bed surface (31), a second heat exchange coil (32) is fixedly arranged on the lower surface of the transmission bed surface (31), a vibration layer (33) is connected below the transmission bed surface (31), and a vibrator (331) is installed on the vibration layer (33); The vibration layer (33) is supported by a shock absorbing structure (34); The cooling medium output end of the second heat exchange coil (32) is connected to the cooling medium input end of the first heat exchange coil (151).

5. The cooling device for urea production according to claim 2, characterized in that: The dust removal device (2) comprises a cyclone dust collector (21), a third fan (22), a bag dust collector (23) and a water washing tower (24) which are sequentially connected in series.

6. The cooling device for urea production according to claim 1, characterized in that: An axial flow fan (131) is arranged in the air inlet window (13).

7. The cooling device for urea production according to any one of claims 1 to 6, characterized in that: A demister (141) is arranged in the connecting tube (14).

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