Urea granulation method and urea granulation device

Abstract

Provided is a urea granulation method with which urea particles having stable quality can be obtained. The present invention relates to a urea granulation method using a urea granulation tower having an exhaust port provided at the top of the tower, a spray unit for molten urea, a plurality of atmosphere intake ports, and a recovery unit for granulated urea particles. In the urea granulation tower, a spray unit for molten urea is disposed on the upper part side of the urea granulation tower, a plurality of atmosphere intake ports are disposed on the lower part side of the urea granulation tower, a recovery unit is disposed at the bottom of the tower on the lower part side of the atmosphere intake ports, and the plurality of atmosphere intake ports are disposed at intervals in the circumferential direction. According to the urea granulation method of the present invention, molten urea is sprayed inside a urea granulation tower, and the atmosphere at the ambient temperature of the urea granulation tower is taken in from below to above from an atmosphere intake port, thereby cooling and solidifying the molten urea to form urea particles, and in the process, except for the atmosphere at the ambient temperature, the urea particles are formed in the urea granulation tower. The inside of the urea granulation tower is heated by further supplying heated air having a temperature higher than the ambient temperature.

Description

Technical Field

[0001] The present invention relates to a urea granulation method and a urea granulation device suitable for implementing the urea granulation method. Background Art

[0002] As shown in Japanese Patent Publication No. 2016-500678 Figure 1 As described in paragraphs 0006 to 0007, a granulation method using a granulation tower is known for producing urea particles. Figure 1 The invention of the granulation tower, the granulation tower and the granulation method for improving the overall efficiency and the quality of the final product is shown as a preferred embodiment. Figure 2 and Figure 3 Granulation tower.

[0003] In addition, US2002 / 0056931 and EP3995487 disclose methods of introducing atmospheric air into a granulation tower when granulating urea particles in the granulation tower. In addition, as an environmental measure, an apparatus equipped with an acid cleaning device for exhaust gas treatment is also known. Summary of the Invention

[0004] An object of the present invention is to provide a urea granulation method capable of reducing the water content in produced urea particles and a urea granulation apparatus suitable for carrying out the granulation method.

[0005] The present invention provides a urea granulation method using a urea granulation tower. The urea granulation tower includes an exhaust port provided at the top of the tower, a molten urea spraying portion, a plurality of atmospheric air intakes, and a recovery portion for granulated urea particles. The urea granulation tower includes the molten urea spraying portion disposed at the upper side of the urea granulation tower, the plurality of atmospheric air intakes disposed at the lower side of the urea granulation tower, and the recovery portion disposed at the bottom of the tower below the atmospheric air intakes. The plurality of atmospheric air intakes are circumferentially spaced apart. The molten urea is sprayed into the urea granulation tower, and atmospheric air at the ambient temperature of the urea granulation tower is taken in from below to above through the atmospheric air intakes, thereby cooling and solidifying the molten urea to form urea particles. During this process, in addition to the atmospheric air at the ambient temperature, heated air having a temperature higher than the ambient temperature is supplied to heat the interior of the urea granulation tower.

[0006] The present invention also provides a urea granulation apparatus comprising a urea granulation tower and a heated air supply device, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of atmospheric air intakes, and a recovery portion for granulated urea particles; the molten urea spray portion is arranged at the upper side of the urea granulation tower, the plurality of atmospheric air intakes are arranged at the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower below the atmospheric air intakes, wherein the plurality of atmospheric air intakes are arranged at intervals in the circumferential direction; and the heated air supply device has a heated air production portion and a heated air supply line for supplying heated air produced by the heated air production portion into the urea granulation tower.

[0007] According to the urea granulation method of the present invention, urea granules having a low water content and stable quality can be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [ Figure 1 ] is a front view of a urea granulation device suitable for implementing a urea granulation method, in which a portion of the outer wall is removed in order to understand the internal structure.

[0009] [ Figure 2 ]yes Figure 1 A cross-sectional view in the width direction, in which the heated air supply device is a top view.

[0010] [ Figure 3 ]yes Figure 1 A partial enlarged view of .

[0011] [ Figure 4 ]yes Figure 1 Other implementations are equivalent to Figure 3 A partial enlarged view of .

[0012] [ Figure 5 ]yes Figure 4 Other implementations are equivalent to Figure 3 A partial enlarged view of .

[0013] [ Figure 6 ]yes Figure 1 and Figure 4 The other embodiments shown are equivalent to Figure 3 A partial enlarged view of .

[0014] [ Figure 7 ] is included Figure 6 A partially enlarged longitudinal cross-sectional view of the atmosphere intake port shown.

[0015] [ Figure 8 ]yes Figure 1 、 Figure 4 and Figure 6Another embodiment shown is equivalent to Figure 3 A partial enlarged view of .

[0016] [ Figure 9 ]yes Figure 1 、 Figure 4 、 Figure 6 as well as Figure 8 The other embodiments shown are equivalent to Figure 3 A partial enlarged view of . DETAILED DESCRIPTION

[0017] <Urea Granulation Method>

[0018] The urea granulation method of the present invention can use the method of Japanese Patent Publication No. 2016-500678. Figure 1 or Figure 2 and Figure 3 The known urea granulation tower shown and the device obtained by adding the equipment required for the implementation of the present invention to the above-mentioned known urea granulation tower are implemented. The known urea granulation tower has an exhaust port provided at the top of the tower, a spray section for molten urea, multiple atmospheric intakes, and a recovery section for urea particles after granulation. When the urea granulation method of the present invention is implemented, the exhaust port provided at the top of the tower does not require an acid cleaning device for exhaust gas treatment, so the acid cleaning process for exhaust gas treatment is also not required in the urea granulation method. The spray section for molten urea is arranged on the upper side of the urea granulation tower, the multiple atmospheric intakes are arranged on the lower side of the urea granulation tower, and the recovery section is arranged at the bottom of the tower on the lower side of the above-mentioned atmospheric intakes. The multiple atmospheric intakes are arranged at intervals in the circumferential direction. The planar shape of the multiple atmospheric intakes is not particularly limited, and is preferably square or rectangular.

[0019] In a conventional granulation method using a known urea granulation tower, molten urea is sprayed inside the urea granulation tower. Air at the ambient temperature of the urea granulation tower is introduced from below to above through an air inlet. This cools and solidifies the molten urea to form urea particles. The molten urea can be the same as the liquid phase (molten urea) supplied to the spraying equipment described in Japanese Patent Application Publication No. 2016-500678.

[0020] The present invention is characterized by comprising the step of supplying, in addition to the ambient temperature of the urea granulation tower, heated air having a temperature higher than the ambient temperature, thereby heating the interior of the urea granulation tower. Therefore, in addition to the conventional urea granulation tower, the present invention requires equipment for producing heated air and equipment for supplying heated air to the urea granulation tower (the aforementioned equipment required for the implementation of the present invention).

[0021] The atmosphere at the ambient temperature around the urea granulation tower is the atmosphere inside (or outside) the factory equipped with the urea granulation tower, and the temperature of the atmosphere varies according to seasons and time periods within a day (i.e., there are temperature fluctuations). For example, when the temperature drops as in winter or at night, the atmosphere taken into the urea granulation tower from the air intake port comes into contact with the urea particles, causing the urea particles to be excessively cooled and absorb moisture in the taken-in atmosphere during cooling. As a result, it is considered that there is a problem of an increase in the moisture content in the product (manufactured urea particles). However, by providing a process of heating the inside of the urea granulation tower by supplying heated air with a temperature higher than the ambient temperature as described above, it is possible to prevent the problem of an increase in the moisture content in the product (manufactured urea particles) as described above.

[0022] As a preferred embodiment, the urea granulation method of the present invention can implement the following method: taking the temperature at the highest ambient temperature (ambient temperature) around the urea granulation tower as the assumed maximum temperature in the design of the urea granulation tower, and when the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air with a temperature higher than the ambient temperature is also supplied to heat the inside of the urea granulation tower.

[0023] The assumed maximum temperature in the design of the urea granulation tower is the temperature at the highest ambient temperature (ambient temperature) around the urea granulation tower, specifically, the temperature during the daytime in summer. The assumed maximum temperature (T1) in the design of the urea granulation tower varies depending on multiple factors such as region and the surrounding environment where the factory equipped with the urea granulation tower is located, even during the daytime in summer. When the ambient temperature (T2) around the urea granulation tower is lower than the assumed maximum temperature (T1) (T2 < T1), in addition to supplying the atmosphere at the ambient temperature (T2), heated air (T3) with a temperature higher than the ambient temperature (T2) is also supplied to heat the inside of the urea granulation tower. At this time, the relationship between T1 and T3 is T3 ≥ T1.

[0024] When implementing the method of supplying heated air (T3) with a temperature higher than the ambient temperature (T2) in addition to supplying the atmosphere at the ambient temperature (T2), it is preferable to implement any one of the following methods: (a) a method of supplying the heated air from the outside of the air intake port while taking in the atmosphere from the air intake port into the interior; (b) a method of supplying a part of the heated air from the outside of the air intake port while taking in the atmosphere from the air intake port into the interior and directly supplying the remaining part of the heated air to the inside of the air intake port; (c) a method of directly supplying the heated air to the inside of the air intake port while taking in the atmosphere from the air intake port into the interior.

[0025] When the method (a) is implemented, the atmospheric air taken in from the atmospheric air inlet is mixed with the heated air and then supplied into the urea granulation tower.

[0026] In the case of implementing the method (b), a portion of the heated air is subjected to the method (a), and the remaining portion of the heated air is directly supplied to the urea granulation tower. Therefore, a method of mixing the remaining portion of the heated air with the introduced atmospheric air in the urea granulation tower is also included.

[0027] When the method (c) is implemented, the entire heated air is mixed with the introduced atmospheric air in the urea granulation tower.

[0028] When implementing the method (a) or (b) above, it is preferred to implement any one method selected from the following methods:

[0029] (ab-1) When the heated air is supplied from outside the atmospheric intake port, the heated air is supplied from a plurality of positions facing the plurality of atmospheric intake ports;

[0030] (ab-2) When supplying the heated air to the atmospheric air intake, the heated air is supplied from a plurality of positions between the plurality of atmospheric air intakes outside the urea granulation tower toward the atmospheric air intakes on both sides.

[0031] When implementing method (ab-1), for example, a method may be implemented as follows: using a heated air supply pipe (main pipe) and a plurality of branch pipes branching therefrom, arranging the heated air supply ports of the branch pipes so as to oppose the atmospheric inlet, and supplying heated air from a plurality of positions opposing the atmospheric inlet. When implementing method (ab-2), for example, a method may be implemented as follows: using a heated air supply pipe (main pipe) and a plurality of branch pipes branching therefrom, using the branch pipes adjusted in shape, size, and position, and supplying heated air so that the heated air supply ports of the plurality of branch pipes are located between adjacent atmospheric inlets, and the heated air supply ports are capable of discharging heated air toward the adjacent atmospheric inlets.

[0032] The method for supplying heated air is not particularly limited. For example, heated air can be supplied using a heated air production device comprising a heater or heat exchanger for heating the atmosphere at the ambient temperature (T2), and optionally combined with a blower for supplying heated air. In this case, the heated air production device and the urea granulation tower are connected by a pipe or the like, and the heated air can be supplied to the urea granulation tower via the pipe.

[0033] When implementing the above-described embodiment of supplying heated air, it is more preferable to consider the operating load factor (the percentage of the average urea granule production during a certain period relative to the maximum urea granule production during the same period) in the urea granulation tower. For example, when the same amount of heated air at the same temperature is supplied to the urea granulation tower at operating load factors of 100% and 50% (e.g., in any of the above embodiments (a) to (c)), while the heating state within the urea granulation tower is sufficient under the operating load factor of 100%, the heating state within the urea granulation tower under the operating load factor of 50% becomes insufficient, resulting in a greater temperature drop within the urea granulation tower. This may result in a problem such as an increase in the moisture content of the product (produced urea granules). Therefore, when the operating load factor within the urea granulation tower is a value (Lx) (%) lower than the maximum value (Lmax) (%), it is preferable to implement a method in which the heated air supply rate is increased as the difference between Lmax and Lx (%) increases. For example, if the supply rate of heated air (temperature T°C) supplied to the urea granulation tower when Lmax = 100% is V, the supply rate of heated air (temperature T°C) when Lx = 50% can be set in the range of 1 V to 5 V. By implementing this, a decrease in the temperature in the urea granulation tower can be suppressed, and an increase in the moisture content of the product (urea granules after production) can be prevented, thereby keeping the moisture content low.

[0034] By implementing the urea granulation method of the present invention, a product (urea particles after production) that satisfies any of the first, second, and third requirements described below can be produced. Preferably, a product (urea particles after production) that satisfies the third requirement can be produced.

[0035] First requirement: The temperature of urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40° C. or higher.

[0036] Second requirement: The moisture content of the urea particles immediately after recovery from the recovery section of the urea granulation tower (measured by using a Karl Fischer titrator or by measuring the loss on drying by heating the analysis sample in a desiccator) is 0.3% or less.

[0037] The third requirement: satisfying both the first and second requirements.

[0038] <Urea granulation device>

[0039] according to Figures 1 to 9 The urea granulation device of the present invention is described below. The urea granulation device of the present invention is a device suitable for implementing the above-mentioned urea granulation method. Figure 1 As shown, the urea granulation apparatus 1 includes a urea granulation tower 10 and a heated air supply device 30 .

[0040] The urea granulation tower 10 has an outer shell (shell) including a tower top 11, a tower bottom 12, and a tower side wall 13. Figure 1 In the figure, the upper portion of the housing is shown with the tower sidewall 13 removed to facilitate the recovery of granulated urea particles. The tower bottom 12 can be formed into a conical shape as shown in the figure. The cross-sectional shape of the urea granulation tower 10 in the width direction (a direction perpendicular to the height direction) is preferably circular, but is not limited to this and can be a polygon such as a quadrilateral or hexagon, or other shapes.

[0041] An exhaust port 14 is provided at the tower top 11. A molten urea spraying section 15 is provided above the urea granulation tower 10 and below the tower top 11. This section is connected to a molten urea supply unit (not shown) via a molten urea supply line 15a. A plurality of atmospheric air intakes 16 (16a to 16h) are provided at the bottom of the urea granulation tower 10. The plurality of atmospheric air intakes 16 are spaced apart in the circumferential direction. A recovery section 17 for urea particles granulated within the urea granulation tower 10 is provided at the tower bottom 11, further below the atmospheric air intakes 16.

[0042] The size of the urea granulation tower 10 can be appropriately determined in consideration of manufacturing capacity, site selection conditions, etc. For example, the urea granulation tower 10 can be cylindrical with a height of 50m to 150m and a diameter of 10m to 30m, and the air intake 16 can be 3m×9m in size.

[0043] The heated air supply device 30 includes a heated air production unit 31 and a heated air supply line 40 for supplying heated air produced by the heated air production unit 31 into the urea granulation tower 10. The heated air production unit 31 can use a device equipped with a heating device 33 for taking in air and a blower 34 for conveying the heated air. The heating device 33 can be a heater or a heat exchanger, for example. The heated air supply line 40 includes a pipe capable of supplying the heated air produced in the heated air production unit 31 to the urea granulation tower 10. In the heated air supply line 40, the heated air outlet 32 of the heated air production unit 31 is connected to the first end opening 41 of the heated air supply line 40, and the second end opening 48 of the heated air supply line 40 is connected to the multiple air intakes 16 of the urea granulation tower 10.

[0044] exist Figures 1 to 3In the illustrated embodiment, the second end opening 48 of the heated air supply line 40 includes an annular portion 42 and a plurality of heated air discharge portions 43 (43a to 43h) arranged perpendicularly from the annular portion 42. The heated air discharge portions 43 (43a to 43h) include a hollow columnar portion 44 and heated air discharge ports 45 formed on a surface spaced apart from the atmospheric air intake 16 (16a to 16h) of the urea granulation tower 10. The cross-sectional shape of the hollow columnar portion 44 in the width direction can be circular, polygonal, elliptical, or the like, but is not limited thereto.

[0045] The heated air outlet 45 may be a slit-shaped opening or a group of fine holes. Figures 1 to 3 In the illustrated embodiment, since the heated air discharge port 45 is spaced apart from and opposed to the atmosphere intake port 16 ( 16 a to 16 h ), heated air is supplied from the outside of the urea granulation tower 10 into the atmosphere intake port 16 ( 16 a to 16 h ).

[0046] exist Figures 1 to 3 In the embodiment, by arranging part or all of the heated air discharge portion 43 (43a to 43h) to enter the atmosphere intake port 16 (16a to 16h), it is also possible to realize an embodiment in which the heated air is discharged directly into the urea granulation tower 10. When the heated air discharge portion 43 (43a to 43h) is arranged so that part of it enters the atmosphere intake port 16 (16a to 16h), part of the heated air is supplied from the outside of the urea granulation tower 10 to the atmosphere intake port 16 (16a to 16h), and the remaining part is discharged directly into the inside of the urea granulation tower 10. When the heated air discharge portion 43 (43a to 43h) is arranged so that all of it enters the atmosphere intake port 16 (16a to 16h), all of the heated air is discharged directly into the inside of the urea granulation tower 10.

[0047] Then, with Figure 1 and Figure 2 Explain together Figure 4 It should be noted that the following Figure 4 implementation methods and Figure 5 、 Figure 6 、 Figure 8 as well as Figure 9 The embodiments of FIG. 1 and 2 only illustrate a portion of the atmosphere inlet. Figures 1 to 3 The embodiment of has an atmosphere inlet 16 (16a to 16h) in the same manner. Figure 4 In the embodiment of Figure 4 The heated air discharge portion 143 (143a-143b) and Figures 1 to 3The embodiments of the present invention are the same except that the arrangement of the heated air discharge portion 43 (43a to 43c) is different. The heated air discharge portion 143 (143a to 143b) is vertically provided from the annular portion 42 so as to be located in the middle position of the circumferential direction of the adjacent atmosphere intake port 16 (16a to 16c). The heated air discharge portion 143 (143a to 143b) and the tower side wall portion 13 can be spaced apart or in contact with each other, but in Figures 1 to 3 In the embodiment shown, the heated air discharge parts 43 are spaced apart and opposed to each other. The heated air discharge parts 143 (143a-143b) have a hollow column 144 and two slit-shaped heated air discharge ports 145 having a group of pores that are opposed to each other in the horizontal direction of the hollow column 144 (along the direction of the tower side wall 13). The cross-sectional shape of the hollow column 144 in the width direction can be set to a circular, polygonal, elliptical, etc., but is not limited thereto. Figure 4 In the embodiment shown, two heated air discharge portions 143 may be arranged between adjacent atmospheric inlets (16a and 16b or 16b and 16c). In this case, the heated air discharge port 145 having a slit shape or a group of fine holes may be formed only at one position close to the atmospheric inlet. Figure 4 In the embodiment, the heated air discharged from the heated air discharge port 145 (145a to 145b) is supplied from the outside of the urea granulation tower 10 to the atmosphere intake port 16 (16a to 16c).

[0048] In addition, regarding the urea granulation device, Figure 4 When the embodiment shown is set as the first embodiment, in addition to the first embodiment, it may also include Figure 5 The second or third method shown in FIG. Figure 5 Although both the second aspect and the third aspect are shown in the figure, an embodiment may be performed using only the second aspect or only the third aspect. Figure 5The second embodiment shown has a second hollow column 146 that branches off from the heated air discharge portion 143a and has an opening portion (not shown) extending in the direction along the annular portion 42. In this case, the second hollow column 146 may also extend from one heated air discharge portion 143 in any one direction or in both directions toward the atmosphere intake port 16. For example, it may extend from the heated air discharge portion 143a to any one direction or in both directions of the atmosphere intake ports 16a and 16b. In addition, it may extend from the heated air discharge portion 143b to any one direction or in both directions of the atmosphere intake ports 16b and 16c. The position of the opening portion of the second hollow column 146 is adjusted so as to be able to discharge heated air directly from the lower side of the atmosphere intake ports 16a to 16c (the side close to the annular portion 42) to the interior of the atmosphere intake ports 16a to 16c. When heated air is supplied to the atmosphere intake ports 16a to 16c, heated air (warm light air) is easily taken into the urea granulation tower 10 from the upper side (the side away from the annular portion 42) of the atmosphere intake ports 16a to 16c. Figure 5 In the second embodiment, heated air is taken in from all of the atmosphere intake ports 16a to 16c.

[0049] Figure 5 The third method shown is the following method: there are multiple third hollow columnar portions 147, which have opening portions (not shown) vertically arranged from the annular portion 42, and the opening portions of the third hollow columnar portions 147 are arranged opposite to the atmosphere inlets 16a to 16c. The third hollow columnar portion 147 is vertically arranged from the annular portion 42 at the middle position of the circumference corresponding to the heated air discharge portion 143a to 143c, and is adjusted so that the opening portion is arranged opposite to the atmosphere inlets 16a to 16c. The position of the third hollow portion 147 is adjusted so that heated air can be discharged from the lower side of the atmosphere inlets 16a to 16c (the side close to the annular portion 42) to the interior of the atmosphere inlets 16a to 16c. In the implementation Figure 5 In the third embodiment, the same effect as the second embodiment described above can be obtained.

[0050] Then, with Figures 1 to 4 Explain together Figure 6 In addition, Figure 6 In the embodiment of Figure 5 Likewise, a second hollow column 146 or a third hollow column 147 is provided. Figure 6 The difference in the implementation of Figure 4In the embodiment, the air intake 16 (16a-16c) is provided with a plurality of adjustment members 50a, 50b, and 50c for adjusting the amount and direction of air flow. Each adjustment member 50a includes a rotating shaft 51 rotatably mounted on both sides of the width direction of the air intake 16a and a blade plate 52 fixed to the rotating shaft 51. A total of four adjustment members 50a are provided in the air intake 16a, and the four adjustment members 50a function as a Venetian blind.

[0051] Regarding the four mounted adjustment members 50a (blinds), the rotation shaft 51 of each adjustment member 50a is rotated to adjust the angle α between the surface of the air intake 16a and the surface of the blade plate 52 (see Figure 7 ) varies between 0 degrees and 90 degrees, thereby enabling the opening area of the atmosphere inlet 16a to be increased or decreased as a whole. As a result, the inflow amount from the atmosphere inlet 16a, the inflow direction from the atmosphere inlet 16a to the inside, or both the inflow amount and the inflow direction can be adjusted. Four adjustment members 50b (Venetian blinds) are installed at the atmosphere inlet 16b, and four adjustment members 50c (Venetian blinds) are installed at the atmosphere inlet 16c, which function in the same way as the adjustment members 50a. The required number of components identical to the adjustment members 50a are also installed at the remaining atmosphere inlets not shown in the figure. In Figure 6 In the embodiment shown, two heated air discharge portions 143 may be arranged between adjacent atmospheric inlets (16a and 16b or 16b and 16c). In this case, the heated air discharge port 145 having a slit shape or a group of fine holes may be formed only at one location close to the atmospheric inlet. Figure 6 In the embodiment, the heated air discharged from the heated air discharge port 145 is supplied from the outside of the urea granulation tower 10 to the atmosphere intake port 16 ( 16 a to 16 c ).

[0052] Then, with Figures 1 to 6 Explain together Figure 8 It should be noted that in Figure 8 In the embodiment of Figure 5 Likewise, a second hollow column 146 or a third hollow column 147 is provided. Figure 8 The difference in the implementation of Figure 4 The air intake ports 16 (16a to 16c) in the embodiment of the present invention are provided with adjustment members 60a and 60b for adjusting the inflow amount and inflow direction of the air. The adjustment member 60a has a rotating shaft 61 rotatably mounted on both ends of the longitudinal direction of the air intake port 16a and a blade plate 62 fixed to the rotating shaft 61. The adjustment members 60a and 60b adjust the angle α (refer to FIG. 1 ) between the surface of the air intake ports 16a and 16b and the surface of the blade plate 62 by rotating the respective rotating shafts 61. Figure 7) changes between 0 degrees and 90 degrees, thereby being able to increase or decrease the opening area of the atmosphere intake ports 16a, 16b as a whole. As a result, it is possible to adjust the inflow amount from the atmosphere intake ports 16a, 16b, the inflow direction from the atmosphere intake ports 16a, 16b to the inside, or both the inflow amount and the inflow direction. Figure 8 In the embodiment shown, two heated air discharge portions 143 may be arranged between adjacent atmospheric intake ports (16a and 16b). In this case, the heated air discharge port 145 having a slit shape or a group of fine holes may be formed only at one location close to the atmospheric intake port. Figure 8 In the embodiment, the heated air discharged from the heated air discharge port 145 is discharged from the outside of the urea granulation tower 10 into the atmosphere intake port 16 (16a-16b).

[0053] As a substitute for Figure 6 as well as Figure 8 The adjusting members 50a, 50b, 50c or the adjusting members 70a, 70b, 70c of the adjusting members 60a, 60b used in the embodiment shown can use one or more gates installed at the atmosphere intake ports 16a to 16c respectively. Figure 9 As shown, for example, by installing a gate at one location on the upper side or lower side of the atmosphere inlet 16a~16c or at two locations on the upper side and the lower side, the opening area of the atmosphere inlet 16a~16c can be increased or decreased by lowering or raising the above-mentioned gate.

[0054] Depending on a number of factors, such as the installation location and the processing volume, the urea granulation apparatus 1 may be any one of the following embodiments (A) to (D): (A) a urea granulation apparatus comprising a combination of one urea granulation tower 10 and one heated air supply device 30, (B) a urea granulation apparatus comprising a combination of one urea granulation tower 10 and a plurality of heated air supply devices 30, (C) a urea granulation apparatus comprising a combination of a plurality of urea granulation towers 10 and a single heated air supply device 30, and (D) a urea granulation apparatus comprising a combination of a plurality of urea granulation towers 10 and a plurality of heated air supply devices 30.

[0055] The urea granulation device 1 is preferably capable of implementing the following embodiment: the temperature at which the ambient temperature (ambient temperature) around the urea granulation tower 10 is the highest is used as the assumed maximum temperature in the design of the urea granulation tower 10. When the ambient temperature around the urea granulation tower 10 is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air having a temperature higher than the ambient temperature is supplied by the heated air supply device 30, thereby heating the inside of the urea granulation tower 10.

[0056] When the urea granulation apparatus 1 is implemented in the above-described embodiment, it is preferable to implement the following embodiment: when the operation load factor (the percentage of the average urea granule production amount in a certain period to the maximum urea granule production amount in the same period) in the urea granulation tower 10 is a value (Lx) (%) lower than the maximum value (Lmax) (%), the greater the difference between Lmax and Lx (%), the greater the supply amount of heated air from the heated air supply device 30 can be.

[0057] When urea granules are produced using the urea granulation apparatus 1, the urea granulation apparatus 1 preferably satisfies the following first, second, or third requirements. The first requirement is that the temperature of the urea granules immediately after being recovered from the recovery section 17 of the urea granulation tower 10 be maintained at 40°C or higher. The second requirement is that the moisture content of the urea granules immediately after being recovered from the recovery section 17 of the urea granulation tower 10 be maintained at 0.3% or lower (measured by a Karl Fischer titrator or by measuring loss on drying by heating an analysis sample in a desiccator). The third requirement is that both the first and second requirements be satisfied.

[0058] <Urea Granulation Method Using Urea Granulation Apparatus 1 (Operation Method of Urea Granulation Apparatus 1)>

[0059] Next, use Figures 1 to 9 The following describes a urea granulation method using the urea granulation apparatus 1 (i.e., a method for operating the urea granulation apparatus 1). Molten urea is sprayed from a molten urea spraying section 15 into the interior of the urea granulation tower 10. The molten urea can be the same liquid phase (molten urea) supplied to the spraying equipment described in Japanese Patent Publication No. 2016-500678. When spraying the molten urea, air at the ambient temperature of the urea granulation tower 10 is introduced from the bottom to the top through the air intakes 16a to 16h. This cools and solidifies the molten urea, forming urea particles.

[0060] The atmosphere at the ambient temperature of the urea granulation tower 10 is the atmosphere in the factory where the urea granulation tower 10 is installed (or the atmosphere outside the factory). The temperature of the atmosphere varies depending on the season and the time of day (i.e., there is a temperature fluctuation). For example, when the temperature drops, such as in winter or at night, the atmosphere introduced into the urea granulation tower 10 from the atmosphere inlet comes into contact with the urea particles, causing the urea particles to be excessively cooled. The urea particles absorb moisture in the atmosphere introduced during the cooling process, and as a result, it is believed that the moisture content in the product (the urea particles after production) becomes high. When using Figures 1 to 9When implementing the urea granulation method of the urea granulation device 1, in addition to supplying the atmosphere at the temperature around the urea granulation tower 10, heated air with a temperature higher than the above-mentioned ambient temperature is also supplied from the heated air supply device 30 to heat the inside of the urea granulation tower 10. By setting the process of supplying heated air with a temperature higher than the above-mentioned ambient temperature to heat the inside of the urea granulation tower 10, it is possible to prevent the problem that the moisture content in the product (urea particles after manufacturing) becomes high as described above, and the moisture content can be suppressed to a low level. The manufactured urea particles are recovered by the recovery unit 17 to become products with stable quality.

[0061] When implementing the use of Figures 1 to 9 the urea granulation method of the urea granulation device 1, the following method can be implemented: The temperature when the ambient temperature (ambient temperature) around the urea granulation tower 10 is the highest is used as the assumed maximum temperature in the design of the urea granulation tower 10. When the ambient temperature around the urea granulation tower 10 is lower than the above-mentioned assumed maximum temperature, in addition to supplying the atmosphere at the above-mentioned ambient temperature, heated air with a temperature higher than the above-mentioned ambient temperature is also supplied, thereby heating the inside of the urea granulation tower 10.

[0062] The assumed maximum temperature in the design of the urea granulation tower 10 is the temperature when the ambient temperature (ambient temperature) around the urea granulation tower 10 is the highest, specifically, the temperature during the daytime in summer.

[0063] The assumed maximum temperature (T1) in the design of the urea granulation tower 10 varies depending on multiple factors such as the region and the surrounding environment where the factory with the urea granulation tower 10 is located, even during the daytime in summer. When the ambient temperature (T2) around the urea granulation tower 10 is lower than the above-mentioned assumed maximum temperature (T1) (T2 < T1), in addition to supplying the atmosphere at the above-mentioned ambient temperature (T2), heated air with a temperature higher than the above-mentioned ambient temperature (T2) (T3) is also supplied, thereby heating the inside of the urea granulation tower 10. At this time, the relationship between T1 and T3 is T3 ≥ T1.

[0064] When implementing the use of Figures 1 to 9When implementing the urea granulation method of the urea granulation apparatus 1, it is more preferable to consider the operation load factor (the percentage of the average urea granule production amount in a certain period relative to the maximum urea granule production amount in the same period) of the urea granulation tower 10. When the operation load factor (the percentage of the average urea granule production amount in a certain period relative to the maximum urea granule production amount in the same period) of the urea granulation tower 10 is a value (Lx) (%) lower than the maximum value (Lmax) (%), the supply amount of heated air is increased as the difference between Lmax and Lx (%) increases. For example, when the same amount of heated air at the same temperature is supplied to the urea granulation tower 10 at operating loads of 100% and 50%, while the heating state within the urea granulation tower 10 is sufficient at the 100% operating load, the heating state within the urea granulation tower 10 is insufficient at the 50% operating load, resulting in a greater temperature drop within the urea granulation tower 10. Consequently, this may cause a problem in which the moisture content in the product (produced urea granules) increases. Therefore, when the operating load of the urea granulation tower 10 is a value (Lx) (%) lower than the maximum value (Lmax) (%), it is preferable to increase the heated air supply rate as the difference between Lmax and Lx (%) increases. For example, if the heated air supply rate (temperature T°C) supplied to the urea granulation tower at Lmax = 100% is V, the heated air supply rate (temperature T°C) at Lx = 50% can be set to a range of 1V to 5V. By performing such an operation, a temperature drop in the urea granulation tower 10 is suppressed, and an increase in the moisture content of the product (the produced urea granules) can be prevented, thereby obtaining a product with a suppressed moisture content.

[0065] In the urea granulation method using the urea granulation device 1, Figure 3 、 Figure 4 、 Figure 6 、 Figure 8 When each device is shown, the method of supplying heated air to the urea granulation tower 10 is different. Figure 3 In the apparatus shown, heated air produced by the heated air producing section 31 is supplied from the outside of the urea granulation tower 10 to the atmosphere inlets 16a to 16h through a heated air supply line 40, an annular section 42, and heated air discharge sections 43 (43a to 43h) toward the inside of the urea granulation tower 10. At this time, heated air is supplied to the interior of the urea granulation tower 10 while taking in outside air near the atmosphere inlets 16a to 16h.

[0066] exist Figure 4In the illustrated apparatus, heated air produced by the heated air production unit 31 is supplied from the outside of the urea granulation tower 10 to the atmosphere intake ports 16a to 16c via a heated air supply line 40, an annular portion 42, and heated air discharge ports 143 (143a to 143b). The heated air discharged from the slit-shaped heated air discharge ports 145 or the heated air discharge ports 145 having a group of fine holes in the heated air discharge ports 143 (143a to 143b) moves circumferentially along the tower sidewall 13 while drawing in ambient air, and is then supplied from the atmosphere intake ports 16 (16a to 16c) into the urea granulation tower 10. The mixed air of the heated air and the outside air supplied into the urea granulation tower 10 mixes with the air within the urea granulation tower 10, thereby raising the internal temperature of the urea granulation tower 10.

[0067] exist Figure 6 In the illustrated apparatus, heated air produced by the heated air production unit 31 is supplied from the outside of the urea granulation tower 10 to the atmosphere intake ports 16a to 16c using a heated air supply line 40, an annular portion 42, and heated air discharge ports 143 (143a-143b). The heated air discharged from the slit-shaped heated air discharge ports 145 of the heated air discharge ports 143 (143a-143b) moves circumferentially along the tower sidewall 13 while drawing in ambient air, and is then supplied from the atmosphere intake ports 16 (16a-16c) into the urea granulation tower 10. At this time, the amount of mixed air flowing into the atmosphere intake ports 16a to 16c can be adjusted by operating the adjustment members 50a-50c attached to the atmosphere intake ports 16a to 16c to increase or decrease the opening area of the atmosphere intake ports 16a to 16c. The mixed air of the heated air and the external air supplied into the urea granulation tower 10 is mixed with the air in the urea granulation tower 10 , thereby increasing the internal temperature of the urea granulation tower 10 .

[0068] exist Figure 8 In the illustrated apparatus, heated air produced by the heated air producing section 31 is supplied from the outside of the urea granulation tower 10 to the atmosphere intake ports 16a-16b via a heated air supply line 40, an annular portion 42, and a heated air discharge portion 143. The heated air discharged from the slit-shaped heated air discharge ports 145 or the heated air discharge ports 145 having a group of fine holes in the heated air discharge portion 143 moves in the circumferential direction along the tower sidewall 13 and is supplied from the atmosphere intake ports 16 (16a-16b) into the interior of the urea granulation tower 10 together with the surrounding external air.

[0069] By implementing Figures 1 to 9 The urea granulation method of the urea granulation apparatus 1 can satisfy any one of the following first, second and third requirements.

[0070] (First requirement)

[0071] The temperature of urea particles immediately after being recovered from the recovery section (17) of the urea granulation tower (10) can be set to 40°C or higher.

[0072] (Second requirement)

[0073] The moisture content of urea particles immediately after being recovered from a recovery section (17) of a urea granulation tower (10) can be reduced to 0.3% or less (measured by using a Karl Fischer titrator or by heating an analysis sample in a desiccator and measuring the loss on drying).

[0074] (Third requirement)

[0075] Both the first requirement and the second requirement are satisfied.

[0076] The present invention includes the following inventions.

[0077] (1) A urea granulation method using a urea granulation tower, the urea granulation tower having an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; in the urea granulation tower, the molten urea spraying portion is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower below the air intakes, the plurality of air intakes being arranged at intervals in the circumferential direction; the molten urea is sprayed inside the urea granulation tower, and air at the ambient temperature of the urea granulation tower is taken in from below to above through the air intakes, thereby cooling and solidifying the molten urea to form urea particles, and in this process, in addition to supplying the air at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the interior of the urea granulation tower.

[0078] (2) A urea granulation method using a urea granulation tower, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; in the urea granulation tower, the molten urea spray portion is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower below the air intakes, and the plurality of air intakes are arranged at intervals in the circumferential direction; the molten urea is granulated in the interior of the urea granulation tower. The urea granulation tower is sprayed with air at the ambient temperature of the urea granulation tower from the bottom to the top through the air inlet, thereby cooling and solidifying the molten urea to form urea particles. In this process, the temperature of the environment (ambient temperature) around the granulation tower is the highest as the assumed maximum temperature in the design of the urea granulation tower. When the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying the air at the ambient temperature, heated air with a temperature higher than the ambient temperature is supplied to heat the inside of the urea granulation tower.

[0079] (3) A urea granulation method using a urea granulation tower, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; in the urea granulation tower, the molten urea spray portion is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower below the air intakes, and the plurality of air intakes are arranged at intervals in the circumferential direction; the molten urea is sprayed inside the urea granulation tower, and the urea particles at the upper side are discharged from the air intakes. Atmosphere at the ambient temperature of the urea granulation tower is drawn upward from below, thereby cooling and solidifying molten urea to form urea granules. In this process, when the interior of the urea granulation tower is heated by supplying heated air having a temperature higher than the ambient temperature in addition to the atmosphere at the ambient temperature, if an operation load factor (the percentage of the average urea granule production amount in a certain period to the maximum urea granule production amount in the same period) in the urea granulation tower is a value (Lx) (%) lower than a maximum value (Lmax) (%), a method is implemented in which the supply rate of heated air is increased as the difference between Lmax and Lx (%) becomes larger.

[0080] (4) The urea granulation method according to any one of (1) to (3), wherein, if the supply rate of heated air (temperature T°C) supplied to the urea granulation tower when Lmax = 100% is V, the supply rate of heated air (temperature T°C) when Lx = 50% can be set in the range of 1V to 5V.

[0081] (5) A method for granulating urea according to any one of (1) to (3), wherein the method for supplying heated air having a temperature higher than the ambient temperature in addition to the ambient air is any one of the following methods: (a) a method for supplying the heated air from the outside of the atmosphere inlet while taking in the atmosphere from the atmosphere inlet; (b) a method for supplying a portion of the heated air from the outside of the atmosphere inlet while taking in the atmosphere from the atmosphere inlet, and directly supplying the remaining portion of the heated air to the inside of the atmosphere inlet; (c) a method for supplying the heated air directly to the inside of the atmosphere inlet while taking in the atmosphere from the atmosphere inlet.

[0082] (6) The urea granulation method according to (5), wherein, when the method of supplying heated air having a temperature higher than the above-mentioned ambient temperature in addition to supplying the atmosphere at the above-mentioned ambient temperature is method (a) or (b), it is any one of the following methods: (ab-1) a method of supplying the heated air from a plurality of positions opposite to the plurality of atmosphere inlets when supplying the above-mentioned heated air from the outside of the above-mentioned atmosphere inlet; (ab-2) a method of supplying the above-mentioned heated air from a plurality of positions between the plurality of atmosphere inlets on the outside of the above-mentioned urea granulation tower toward the atmosphere inlets on both sides when supplying the above-mentioned heated air to the above-mentioned atmosphere inlet.

[0083] (7) The urea granulation method according to any one of (1) to (3), wherein when heated air having a temperature higher than the ambient temperature is supplied in addition to the ambient air at the ambient temperature, the ambient air at the ambient temperature is heated by a heater or a heat exchanger and then supplied.

[0084] (8) The urea granulation method according to any one of (1) to (3), wherein the first requirement is satisfied that the temperature of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40°C or higher, or the second requirement is satisfied that the moisture content of the urea particles immediately after being recovered from the recovery section of the urea granulation tower (measured by a Karl Fischer titrator or by measuring the loss on drying by heating an analysis sample in a desiccator) is 0.3% or less, or both the first and second requirements are satisfied.

[0085] (9) A urea granulation device, comprising a urea granulation tower and a heated air supply device, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of atmospheric intake ports, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of atmospheric intake ports are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower further below the atmospheric intake ports, and the plurality of atmospheric intake ports are arranged at intervals in the circumferential direction; and the heated air supply device has a heated air production portion and a heated air supply pipeline, wherein the heated air supply pipeline is used to supply heated air produced by the heated air production portion into the urea granulation tower.

[0086] (10) A urea granulation device comprising a urea granulation tower and a heated air supply device, wherein the urea granulation tower comprises an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of atmospheric intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of atmospheric intakes are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower further below the atmospheric intakes, and the plurality of atmospheric intakes are arranged at intervals in the circumferential direction; the plurality of atmospheric intakes are respectively provided with an adjusting member for adjusting the inflow amount and inflow direction of atmospheric air, and by increasing or decreasing the opening area of the atmospheric intakes by using the adjusting member, the inflow amount from the atmospheric intakes, the inflow direction from the atmospheric intakes to the inside, or both the inflow amount and the inflow direction are adjusted; and the heated air supply device comprises a heated air production portion and a heated air supply pipeline, and the heated air supply pipeline is used to supply heated air produced by the heated air production portion from the atmospheric intakes to the inside of the urea granulation tower.

[0087] (11) A urea granulation device, comprising a urea granulation tower and a heated air supply device, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery portion is arranged on the bottom of the tower further below the air intakes, and the plurality of air intakes are arranged at intervals in the circumferential direction; the plurality of air intakes are respectively provided with an adjusting member for the inflow amount and inflow direction of the atmosphere, and the adjusting member for the inflow amount and inflow direction is a rotating shaft which can rotate freely and a member fixed to the rotating shaft. The blade plates of the rotating shaft are used as a group and a plurality of these groups are combined to form a venetian blind; in the above-mentioned rotating shaft, the two ends of the rotating shaft are rotatably installed at two opposite positions of the above-mentioned atmospheric inlet, and by rotating the above-mentioned rotating shaft, the angle between the above-mentioned atmospheric inlet surface and the above-mentioned blade plate surface changes between 0 degrees and 90 degrees, thereby adjusting the inflow amount from the above-mentioned atmospheric inlet, the inflow direction from the above-mentioned atmospheric inlet to the inside, or both the above-mentioned inflow amount and the above-mentioned inflow direction; the above-mentioned heated air supply device has a heated air manufacturing part and a heated air supply pipeline, and the above-mentioned heated air supply pipeline is used to supply the heated air manufactured by the above-mentioned heated air manufacturing part from the above-mentioned atmospheric inlet to the above-mentioned urea granulation tower.

[0088] (12) A urea granulation device, comprising a urea granulation tower and a heated air supply device, wherein the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery portion is arranged on the bottom of the tower further below the air intakes, and the plurality of air intakes are arranged at intervals in the circumferential direction; the plurality of air intakes are respectively provided with an adjusting member for the inflow amount and inflow direction of the air, and the air intakes are respectively provided with an adjusting member for the inflow amount and inflow direction of the air. The regulating member for the inflow amount and inflow direction of the gas is a gate installed on the upper end, lower end or other part of the above-mentioned atmosphere inlet, which can reduce and increase the opening area of the above-mentioned atmosphere inlet; by utilizing the above-mentioned gate to reduce and increase the opening area of the above-mentioned atmosphere inlet, the inflow amount from the above-mentioned atmosphere inlet, the inflow direction to the inside or both the above-mentioned inflow amount and the above-mentioned inflow direction are adjusted; the above-mentioned heated air supply device has a heated air manufacturing part and a heated air supply pipeline, and the above-mentioned heated air supply pipeline is used to supply the heated air manufactured by the above-mentioned heated air manufacturing part from the above-mentioned atmosphere inlet to the above-mentioned urea granulation tower.

[0089] (13) A urea granulation device according to any one of technical solutions (9) to (12), wherein, in the above-mentioned urea granulation tower and the above-mentioned heated air supply device, the heated air exhaust port of the above-mentioned heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the above-mentioned heated air supply pipeline is arranged opposite to or directly connected to the multiple atmospheric air inlets of the above-mentioned urea granulation tower at intervals.

[0090] (14) A urea granulation device according to any one of technical solutions (9) to (12), wherein, in the urea granulation tower and the heated air supply device, the heated air discharge port of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to multiple atmospheric air intakes of the urea granulation tower; the second end opening of the heated air supply pipeline is a branch pipe branched into multiple branches, and has any one of the following modes:

[0091] The first mode: the openings of the plurality of branch pipes are arranged to face the plurality of air intake ports.

[0092] The second method is to connect the openings of the plurality of branch pipes to the plurality of air intakes directly.

[0093] The third aspect includes both the first aspect and the second aspect.

[0094] (15) A urea granulation device according to any one of technical solutions (9) to (12), wherein, in the urea granulation tower and the heated air supply device, the heated air discharge port of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to the plurality of atmospheric air intakes of the urea granulation tower; the second end opening of the heated air supply pipeline has an annular portion for the flow of heated air and a plurality of hollow columns arranged at intervals in the circumferential direction of the annular portion and vertically arranged in a manner that allows ventilation from the annular portion, a portion of the hollow column having a slit-shaped opening, or a portion of the hollow column having a plurality of pore groups; the plurality of atmospheric air intakes and the plurality of hollow columns having the slit-shaped opening or the plurality of pore groups have any one of the following modes:

[0095] The first mode is that the plurality of air intake ports are located on the inner side and the plurality of hollow columns are located on the outer side, and the slit-shaped openings or the plurality of pore groups of the plurality of hollow columns are arranged opposite to the plurality of air intake ports.

[0096] The second mode is that the plurality of hollow columns having the slit-shaped openings or the plurality of pore groups are directly connected to the plurality of air intake ports.

[0097] A third embodiment: the plurality of air intake ports and the plurality of hollow columnar portions having the slit-shaped openings or the plurality of pore groups include both the first embodiment and the second embodiment;

[0098] Furthermore, when the first to third aspects are viewed from outside, the plurality of inner air intakes overlap the plurality of outer hollow columns, and the slit-shaped openings or the plurality of pore groups of the hollow columns are located within the air intakes.

[0099] (16) A urea granulation device according to any one of technical solutions (9) to (12), wherein, in the above-mentioned urea granulation tower and the above-mentioned heated air supply device, the heated air discharge port of the above-mentioned heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the above-mentioned heated air supply pipeline is connected to multiple atmospheric inlets of the above-mentioned urea granulation tower; the second end opening of the above-mentioned heated air supply pipeline has an annular portion for the flow of heated air and a plurality of hollow columnar portions arranged at intervals in the circumferential direction of the above-mentioned annular portion and arranged vertically from the above-mentioned annular portion , having a plurality of slit-shaped openings or a plurality of pore groups formed at two different positions of the hollow column; the plurality of air intakes and the plurality of hollow columns having the slit-shaped openings or the plurality of pore groups have a first mode, that is, between adjacent air intakes among the plurality of air intakes, the slit-shaped openings or the plurality of pore groups formed at two different positions of the plurality of hollow columns are respectively configured to be able to release heated air toward the adjacent air intakes; further, as needed, in addition to the first mode, the following second mode or third mode is also provided:

[0100] The second embodiment: The second hollow column is directly connected to the atmosphere inlet, and the second hollow column branches off from the plurality of hollow columns having the slit-shaped opening or the plurality of pore groups, and extends in the direction along the annular portion and has an opening.

[0101] A third embodiment comprises a plurality of third hollow columns, each of which has an opening perpendicularly disposed from the annular portion, the opening of each third hollow column being disposed opposite to and directly connected to the atmosphere inlet;

[0102] In the second and third modes, heated air is released from the lower side of the multiple atmospheric inlets; further, the regulating members for the inflow amount and inflow direction of the adjacent atmospheric inlets are adjusted so that the heated air released from the slit-shaped openings or multiple pore groups formed at two different positions on the multiple hollow columns can flow into the interior.

[0103] (17) A urea granulation device according to any one of technical solutions (9) to (12), wherein the heated air production unit of the heated air supply device includes a heater or heat exchanger for heating the incoming air and a blower for blowing the heated air.

[0104] (18) A urea granulation device according to any one of technical solutions (9) to (12), wherein the urea granulation device is any one selected from the following (A) to (D): (A) a urea granulation device comprising a combination of a urea granulation tower and a heated air supply device; (B) a urea granulation device comprising a combination of a urea granulation tower and a plurality of heated air supply devices; (C) a urea granulation device comprising a combination of a plurality of urea granulation towers and a heated air supply device; and (D) a urea granulation device comprising a combination of a plurality of urea granulation towers and a plurality of heated air supply devices.

[0105] (19) A urea granulation device according to any one of technical solutions (9) to (12), wherein the temperature at which the ambient temperature (ambient temperature) around the urea granulation tower is the highest is used as the assumed maximum temperature in the design of the urea granulation tower. When the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the inside of the urea granulation tower.

[0106] (20) A urea granulation device according to any one of technical solutions (9) to (12), wherein the temperature of the ambient environment (ambient temperature) around the urea granulation tower is the highest as the assumed maximum temperature in the design of the urea granulation tower, and when the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the inside of the urea granulation tower; when the operating load rate (the percentage of the average urea particle production amount in a certain period to the maximum urea particle production amount in the same period) in the urea granulation tower is a value (Lx) (%) lower than the maximum value (Lmax) (%), the greater the difference between Lmax-Lx (%), the greater the supply amount of heated air.

[0107] (21) A urea granulation device according to any one of technical solutions (9) to (12), wherein the device satisfies the first requirement that the temperature of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40°C or higher, or satisfies the second requirement that the moisture content of the urea particles immediately after being recovered from the recovery section of the urea granulation tower (measured by a Karl Fischer titrator or by heating the analysis sample in a dryer and measuring the loss on drying) is 0.3% or lower, or satisfies both the first and second requirements.

[0108] (22) The urea granulation apparatus according to any one of technical solutions (9) to (12), which does not include an acid cleaning device for treating exhaust gas from an exhaust port provided at the top of the urea granulation tower.

[0109] (23) A urea granulation method, which is a urea granulation method using a urea granulation device, wherein the urea granulation device is provided with a urea granulation tower and a heated air supply device; the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery portion is arranged on the bottom of the tower further below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction; the heated air supply device has a heated air production portion and a heating air supply device for recovering the heated air produced by the heated air production portion. Hot air is supplied to a heated air supply line in the urea granulation tower. The urea granulation method includes a first step and a second step. In the first step, while spraying molten urea from a spraying portion of the urea granulation tower, air at the ambient temperature of the urea granulation tower is taken in from the plurality of air intakes from below to above, thereby cooling and solidifying the molten urea to form urea particles. In the second step, urea particles produced in the previous step are recovered from the recovery portion. The first step includes heating the interior of the urea granulation tower by supplying air at the ambient temperature and heated air having a temperature higher than the ambient temperature from a heated air supply device to the plurality of air intakes.

[0110] (24) A urea granulation method, which is a urea granulation method using a urea granulation device, wherein the urea granulation device includes a urea granulation tower and a heated air supply device; the urea granulation tower includes an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of atmospheric intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of atmospheric intakes are arranged on the lower side of the urea granulation tower, and the recovery portion is arranged at the bottom of the tower further below the atmospheric intakes, and the plurality of atmospheric intakes are arranged at intervals in the circumferential direction; the plurality of atmospheric intakes are respectively provided with an adjustment member for the inflow amount and inflow direction of atmospheric air, and the inflow amount from the atmospheric intake, the inflow direction from the atmospheric intake to the inside, or both the inflow amount and the inflow direction are adjusted by increasing or decreasing the opening area of the atmospheric intake using the adjustment member; the heated air supply device includes a heated air production portion and a heated air supply pipeline, and the heated air supply pipeline is provided with a heated air production portion and a heated air supply pipeline. The urea granulation method comprises a first step and a second step. In the first step, while spraying molten urea from a spraying portion of the urea granulation tower, atmospheric air at the ambient temperature of the urea granulation tower is taken in from the plurality of atmospheric air intakes from below toward above, thereby cooling and solidifying the molten urea to form urea particles. In the second step, the urea particles produced in the first step are recovered from the recovery unit. In the first step, when heating the interior of the urea granulation tower by supplying atmospheric air at the ambient temperature and heated air having a temperature higher than the ambient temperature from the heated air supply device to the plurality of atmospheric air intakes, the method comprises adjusting an inflow rate from the atmospheric air intakes, an inflow direction from the atmospheric air intakes into the interior, or both the inflow rate and the inflow direction by increasing or decreasing an opening area of the atmospheric air intakes using an adjusting member for adjusting the inflow rate and inflow direction of the atmospheric air.

[0111] (25) A urea granulation method, which is a urea granulation method using a urea granulation device, wherein the urea granulation device is provided with a urea granulation tower and a heated air supply device; the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery portion is arranged at the bottom of the tower further below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction; the plurality of air intakes respectively have the above-mentioned inflow amount and inflow direction of the air. The regulating member for the above-mentioned inflow amount and inflow direction of the atmosphere is a venetian blind composed of a group of a freely rotatable rotating shaft and a blade plate fixed to the above-mentioned rotating shaft and a combination of these multiple groups; in the above-mentioned rotating shaft, the two ends of the above-mentioned rotating shaft are rotatably installed at two opposite positions of the above-mentioned atmosphere inlet, and by rotating the above-mentioned rotating shaft, the angle between the above-mentioned atmosphere inlet surface and the above-mentioned blade plate surface changes between 0 degrees and 90 degrees, thereby regulating the inflow amount from the above-mentioned atmosphere inlet, the inflow direction from the above-mentioned atmosphere inlet to the inside, or both the above-mentioned inflow amount and the above-mentioned inflow direction; the above-mentioned heated air supply device has a heated air manufacturing part and a heated air supply pipeline, and ... The hot air supply line is used to supply the heated air produced by the heated air producing unit from the atmospheric air intake to the urea granulation tower. The urea granulation method includes a first step and a second step. In the first step, while spraying molten urea from the spraying unit of the urea granulation tower, atmospheric air at the ambient temperature of the urea granulation tower is taken in from the plurality of atmospheric air intakes from below to above, thereby cooling and solidifying the molten urea to form urea particles. In the second step, the urea particles produced in the previous step are recovered from the recovery unit. In the first step, the heated air at the ambient temperature is supplied from the heated air supply device to the plurality of atmospheric air intakes. When heating the inside of the urea granulation tower with atmospheric air and heated air having a temperature higher than the ambient temperature, the process includes adjusting the inflow amount from the atmospheric inlet, the inflow direction from the atmospheric inlet to the interior, or both the inflow amount and the inflow direction by increasing or decreasing the opening area of the atmospheric inlet using an adjusting member for the inflow amount and the inflow direction of the atmospheric air; the adjusting member for the inflow amount and the inflow direction of the atmospheric air is a venetian blind composed of a set of a freely rotatable rotating shaft and blades fixed to the rotating shaft, and combining these sets; the rotating shaft has both ends rotatably mounted at two positions opposite to the atmospheric inlet;By rotating the rotation shaft, the angle between the atmosphere intake port surface and the blade plate surface is varied between 0 and 90 degrees, thereby increasing or decreasing the opening area of the atmosphere intake port, thereby adjusting the amount of air flowing from the atmosphere intake port, the direction of air flowing from the atmosphere intake port into the interior, or both the amount of air flowing and the direction of air flowing.

[0112] (26) A urea granulation method, which is a urea granulation method using a urea granulation device, wherein the urea granulation device is provided with a urea granulation tower and a heated air supply device; the urea granulation tower has an exhaust port provided at the top of the tower, a spray portion for molten urea, a plurality of air intakes, and a recovery portion for granulated urea particles; the spray portion for molten urea is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery portion is arranged at the bottom of the tower further below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction; the plurality of air intakes respectively have the above-mentioned inflow amount of air and an adjusting member for the inflow amount and inflow direction of the atmosphere, the adjusting member for the inflow amount and inflow direction of the atmosphere is a gate installed on the upper end, lower end or other part of the above-mentioned atmosphere inlet, which can reduce and increase the opening area of the atmosphere inlet; by using the above-mentioned gate to reduce and increase the opening area of the above-mentioned atmosphere inlet, the above-mentioned inflow amount from the above-mentioned atmosphere inlet, the above-mentioned inflow direction to the inside, or both the above-mentioned inflow amount and the above-mentioned inflow direction can be adjusted; the above-mentioned heated air supply device has a heated air manufacturing part and a heated air supply pipeline, and the above-mentioned heated air supply pipeline is used to supply the heated air manufactured by the above-mentioned heated air manufacturing part from the above-mentioned atmosphere inlet to the above-mentioned urea granulation tower The urea granulation method includes a first step and a second step. In the first step, while spraying molten urea from the spraying portion of the urea granulation tower, air at the ambient temperature of the urea granulation tower is taken in from the plurality of air intake ports from the bottom to the top, thereby cooling and solidifying the molten urea to form urea particles. In the second step, the urea particles produced in the previous step are recovered from the recovery portion. In the first step, when heating the interior of the urea granulation tower by supplying the air at the ambient temperature and heated air having a temperature higher than the ambient temperature from the heated air supply device to the plurality of air intake ports, the urea granulation method includes: The regulating member for the inflow amount and inflow direction of the gas increases or decreases the opening area of the above-mentioned atmosphere intake port to regulate the inflow amount from the above-mentioned atmosphere intake port, the inflow direction from the above-mentioned atmosphere intake port to the interior, or both the inflow amount and the inflow direction; the regulating member for the inflow amount and inflow direction of the above-mentioned atmosphere is a gate installed on the upper end, lower end or other parts of the above-mentioned atmosphere intake port, which can reduce and increase the opening area of the above-mentioned atmosphere intake port; the above-mentioned gate reduces and increases the opening area of the above-mentioned atmosphere intake port, thereby regulating the inflow amount from the above-mentioned atmosphere intake port, the inflow direction to the interior, or both the inflow amount and the inflow direction.

[0113] (27) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein, in the urea granulation tower and the heated air supply device, the heated air discharge port of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is arranged opposite to or directly connected to the plurality of atmospheric air intakes of the urea granulation tower at intervals.

[0114] (28) The urea granulation method using the urea granulation device according to any one of (23) to (26), wherein, in the urea granulation tower and the heated air supply device, the heated air discharge port of the heated air production unit is connected to the first end opening of the heated air supply pipeline, the second end opening of the heated air supply pipeline is connected to the plurality of atmospheric air intakes of the urea granulation tower, and the second end opening of the heated air supply pipeline is a branch pipe branched into a plurality of branches, and has any one of the following modes:

[0115] The first mode: the openings of the plurality of branch pipes are arranged to face the plurality of air intake ports.

[0116] The second method is to connect the openings of the plurality of branch pipes to the plurality of air intakes directly.

[0117] The third aspect includes both the first aspect and the second aspect.

[0118] (29) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein, in the urea granulation tower and the heated air supply device, the heated air discharge port of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to the plurality of atmospheric air intakes of the urea granulation tower; the second end opening of the heated air supply pipeline has an annular portion for flowing heated air and a plurality of hollow columns arranged at intervals in the circumferential direction of the annular portion and vertically arranged in a manner that allows ventilation from the annular portion, a portion of the hollow column having a slit-shaped opening, or a portion of the hollow column having a plurality of pore groups; the plurality of atmospheric air intakes and the plurality of hollow columns having the slit-shaped opening or the plurality of pore groups have any one of the following modes:

[0119] The first mode is that the plurality of air intake ports are located on the inner side and the plurality of hollow columns are located on the outer side, and the slit-shaped openings or the plurality of pore groups of the plurality of hollow columns are arranged opposite to the plurality of air intake ports.

[0120] The second mode is that the plurality of hollow columns having the slit-shaped openings or the plurality of pore groups are directly connected to the plurality of air intake ports.

[0121] A third embodiment: the plurality of air intake ports and the plurality of hollow columnar portions having the slit-shaped openings or the plurality of pore groups include both the first embodiment and the second embodiment;

[0122] Furthermore, when the first to third aspects are viewed from outside, the plurality of inner air intakes overlap the plurality of outer hollow columns, and the slit-shaped openings or the plurality of pore groups of the hollow columns are located within the air intakes.

[0123] (30) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein, in the above-mentioned urea granulation tower and the above-mentioned heated air supply device, the heated air exhaust port of the above-mentioned heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the above-mentioned heated air supply pipeline is connected to multiple atmospheric air intakes of the above-mentioned urea granulation tower; the second end opening of the above-mentioned heated air supply pipeline has an annular portion for the flow of heated air and a plurality of hollow columnar portions arranged at intervals in the circumferential direction of the above-mentioned annular portion and arranged vertically from the above-mentioned annular portion, and the hollow columnar portions have a plurality of holes along the annular portion at two different positions. A plurality of slit-shaped openings or a plurality of fine pore groups are formed in the length direction; the plurality of atmospheric inlets and the plurality of hollow columns having the slit-shaped openings or the plurality of fine pore groups are configured so that, between adjacent atmospheric inlets among the plurality of atmospheric inlets, the slit-shaped openings or the plurality of fine pore groups formed at two different positions of the plurality of hollow columns can respectively release heated air toward the adjacent atmospheric inlets; further, the regulating members for the inflow amount and inflow direction of the adjacent atmospheric inlets are adjusted so that the heated air released from the slit-shaped openings or the plurality of fine pore groups formed at two different positions of the plurality of hollow columns can flow into the interior.

[0124] (31) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein the heated air production unit of the heated air supply device includes a heater or heat exchanger for heating the incoming air and a blower for blowing the heated air.

[0125] (32) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein the urea granulation device is any one selected from the following (A) to (D): (A) a urea granulation device comprising a combination of a urea granulation tower and a heated air supply device; (B) a urea granulation device comprising a combination of a urea granulation tower and a plurality of heated air supply devices; (C) a urea granulation device comprising a combination of a plurality of urea granulation towers and a heated air supply device; and (D) a urea granulation device comprising a combination of a plurality of urea granulation towers and a plurality of heated air supply devices.

[0126] (33) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein the temperature at which the ambient temperature (ambient temperature) around the urea granulation tower is the highest is used as the assumed maximum temperature in the design of the urea granulation tower, and when the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the inside of the urea granulation tower.

[0127] (34) A urea granulation method using a urea granulation device according to any one of (23) to (26), wherein, in addition to supplying the atmosphere at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby enabling heating of the interior of the urea granulation tower; and when the operating load factor (the percentage of the average urea particle production amount in a certain period relative to the maximum urea particle production amount in the same period) in the urea granulation tower is a value (Lx) (%) lower than the maximum value (Lmax) (%), the greater the difference between Lmax-Lx (%), the greater the supply amount of heated air can be.

[0128] (35) A urea granulation method using a urea granulation apparatus according to any one of (23) to (26), wherein the method satisfies the first requirement that the temperature of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40°C or higher, or satisfies the second requirement that the moisture content of the urea particles immediately after being recovered from the recovery section of the urea granulation tower (measured by a Karl Fischer titrator or by heating an analysis sample in a dryer and measuring the loss on drying) is 0.3% or lower, or satisfies both the first and second requirements.

[0129] (36) The method for granulating urea using the urea granulation apparatus according to any one of (23) to (26), wherein acid cleaning for treating exhaust gas is not performed.

[0130] Example

[0131] Comparative Example 1

[0132] use Figures 1 to 3 The urea granulation apparatus shown (without the heated air supply device 30) granulates urea. The operating load in Table 1 is the operating load rate in the urea granulation tower, and the same applies to Tables 2 to 5. The results are shown in Table 1.

[0133] [Table 1]

[0134] Production volume tons / day 2,7502,063 1,375 Operating load% 100％75％ 50％ Atmospheric temperature deg.C 3535 35 <![CDATA[Intake air volume Nm 3 / h]]> 1,531,0001,531,000 1,531,000 Product temperature deg.C 5048 47

[0135] Example 1

[0136] use Figures 1 to 3 Urea was granulated using the urea granulation apparatus shown. The granulation conditions were identical to those of Comparative Example 1, except that heated air was introduced from the atmospheric inlet. Note that an atmospheric temperature of 35°C was used as the "temperature at which the ambient temperature (surrounding temperature) surrounding the urea granulation tower is at its highest, i.e., the assumed maximum temperature in the design of the urea granulation tower." The results are shown in Table 2.

[0137] [Table 2]

[0138] Production tons / day 2,750 2,063 1,375 Operating load ％ 100％ 75％ 50％ atmospheric temperature deg.C 35 35 35 Intake of atmospheric air <![CDATA[Nm 3 / h]]> 1,531,000 1,443,000 1,399,000 Heating air volume <![CDATA[Nm 3 / h]]> 0 88,000 132,000 Intake of atmospheric air + heating air <![CDATA[Nm 3 / h]]> 1,531,000 1,531,000 1,531,000 Heating air temperature deg.C 70 70 70 Temperature of heated air after mixing with atmosphere deg.C 35 37 38 Product temperature deg.C 50 50 50

[0139] A comparison of the product temperatures in Tables 1 and 2 shows that in Comparative Example 1, where heated air was not supplied during granulation using the urea granulation tower, the product temperature decreased as the operating load decreased, resulting in variations in product quality (moisture content). On the other hand, in Example 1, the product temperature remained constant even when the operating load decreased, indicating that the product quality (moisture content) was stable.

[0140] Comparative Example 2

[0141] use Figures 1 to 3 The urea granulation apparatus shown (without the heated air supply device 30) was used to granulate urea. The results are shown in Table 3.

[0142] [Table 3]

[0143] Production tons / day 2,750 2,750 2,750 Operating load ％ 100％ 100％ 100％ atmospheric temperature deg.C 35 30 25 Intake of atmospheric air <![CDATA[Nm 3 / h]]> 1,531,000 1,531,000 1,531,000 Product temperature deg.C 50 44 38

[0144] Example 2

[0145] use Figures 1 to 3Urea was granulated using the urea granulation apparatus shown. In the granulation method of Comparative Example 2, the same granulation conditions were used, except that heated air was introduced from the atmospheric inlet. It should be noted that an atmospheric temperature of 35°C was used as the "temperature at which the ambient temperature (surrounding temperature) surrounding the urea granulation tower is at its highest, i.e., the assumed maximum temperature in the design of the urea granulation tower." The results are shown in Table 4.

[0146] [Table 4]

[0147] Production tons / day 2,750 2,750 2,750 Operating load ％ 100％ 100％ 100％ atmospheric temperature deg.C 35 30 25 Intake of atmospheric air <![CDATA[Nm 3 / h]]> 1,531,000 1,339,000 1,190,000 Heating air volume <![CDATA[Nm 3 / h]]> 0 192,000 341,000 Intake of atmospheric air + heating air <![CDATA[Nm 3 / h]]> 1,531,000 1,531,000 1,531,000 Heating air temperature deg.C 70 70 70 Temperature of heated air after mixing with atmosphere deg.C 35 35 35 Product temperature deg.C 50 50 50

[0148] A comparison of the product temperatures in Tables 3 and 4 shows that in Comparative Example 2, where heated air was not supplied during granulation using the urea granulation tower, the product temperature decreased as the ambient temperature (temperature of the surrounding environment of the urea granulation tower) decreased, resulting in variations in product quality (moisture content). On the other hand, in Example 2, the product temperature remained constant even when the ambient temperature decreased, indicating that the product quality (moisture content) was stable.

[0149] Comparative Example 3

[0150] use Figures 1 to 3 The urea granulation apparatus shown (without the heated air supply device 30) was used to granulate urea. The results are shown in Table 5.

[0151] [Table 5]

[0152] Production tons / day 2,750 2,750 2,750 Operating load ％ 100％ 100％ 100％ atmospheric temperature deg.C 35 30 25 Intake of atmospheric air <![CDATA[Nm 3 / h]]> 1,531,000 1,058,000 793,000 Product temperature deg.C 50 50 50 Exhaust NH3 concentration <![CDATA[mg / Nm 3 ]]> 50 72 97

[0153] As shown in Table 5, when urea is granulated while maintaining a constant production volume and operating load, reducing the amount of air intake allows operation to maintain product temperature even when the ambient temperature drops. However, this poses the problem of increased ammonia concentration in the exhaust gas. In this case, as an environmental measure, acid cleaning equipment is required for exhaust gas treatment, which leads to other problems such as increased production costs and the generation of by-products, making this undesirable.

[0154] Industrial Application Possibilities

[0155] The urea granulation method of the present invention can be used as a method for producing urea granules with stable quality.

[0156] Description of Reference Numerals

[0157] 1: Urea granulation device,

[0158] 10: Urea granulation tower,

[0159] 11: Top of the tower,

[0160] 12: bottom of the tower,

[0161] 13: Tower side wall,

[0162] 14: Exhaust port,

[0163] 15: Spraying part of molten urea,

[0164] 15a: Molten urea supply line,

[0165] 16 (16a~16h): Atmospheric intake,

[0166] 17: Urea particle recovery unit,

[0167] 30: Heating air supply device,

[0168] 31: Heated air manufacturing department

[0169] 40: Heating air supply line,

[0170] 42: annular part,

[0171] 43 (43a~43h): Heated air discharge portion.

Claims

1. A urea granulation method using a urea granulation tower having an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The urea granulation tower comprises a spraying portion for the molten urea disposed on an upper side of the urea granulation tower, a plurality of air intakes disposed on a lower side of the urea granulation tower, and a recovery portion disposed at a bottom of the tower below the air intakes. The plurality of air intakes are spaced apart in a circumferential direction. The molten urea is sprayed inside the urea granulation tower, and the atmosphere at the ambient temperature of the urea granulation tower is taken in from the bottom to the top through the atmosphere inlet, thereby cooling and solidifying the molten urea to form urea particles. In this process, in addition to the atmosphere at the ambient temperature, heated air with a temperature higher than the ambient temperature is also supplied to heat the inside of the urea granulation tower.

2. A method for granulating urea using a urea granulation tower having an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The urea granulation tower comprises a spraying portion for the molten urea disposed on an upper side of the urea granulation tower, a plurality of air intakes disposed on a lower side of the urea granulation tower, and a recovery portion disposed at a bottom of the tower below the air intakes. The plurality of air intakes are spaced apart in a circumferential direction. The molten urea is sprayed inside the urea granulation tower, and the atmosphere at the ambient temperature of the urea granulation tower is taken in from the bottom to the top through the atmosphere inlet, thereby cooling and solidifying the molten urea to form urea particles. In this process, the ambient temperature of the environment where the urea granulation tower is installed, that is, the temperature when the ambient temperature is the highest, is used as the assumed maximum temperature in the design of the urea granulation tower. When the ambient temperature where the urea granulation tower is installed is lower than the assumed maximum temperature, in addition to supplying the atmosphere at the ambient temperature, heated air with a temperature higher than the ambient temperature is also supplied, thereby heating the inside of the urea granulation tower.

3. A method for granulating urea using a urea granulation tower having an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of atmospheric air intakes, and a recovery portion for granulated urea particles. The urea granulation tower comprises a spraying portion for the molten urea disposed on an upper side of the urea granulation tower, a plurality of air intakes disposed on a lower side of the urea granulation tower, and a recovery portion disposed at a bottom of the tower below the air intakes. The plurality of air intakes are spaced apart in a circumferential direction. The molten urea is sprayed inside the urea granulation tower, and air at the ambient temperature of the urea granulation tower is taken in from the bottom to the top through the air inlet, thereby cooling and solidifying the molten urea to form urea granules. In this process, when heated air having a temperature higher than the ambient temperature is supplied in addition to the ambient temperature to heat the inside of the urea granulation tower, when the operating load rate in the urea granulation tower is a value (Lx) expressed in percentage that is lower than the maximum value (Lmax) expressed in percentage, a method is implemented in which the supply amount of heated air is increased as the difference (Lmax - Lx) expressed in percentage increases. The operation load rate is a percentage of the average urea granule production amount in a certain period relative to the maximum urea granule production amount in the same period.

4. The method for granulating urea according to any one of claims 1 to 3, wherein The method of supplying heated air having a temperature higher than the ambient temperature in addition to the ambient air is any one method selected from the following methods: (a) A method in which the heated air is supplied from the outside of the atmosphere intake port while the atmosphere is taken in from the atmosphere intake port. (b) a method in which atmospheric air is taken in from the atmospheric inlet, a portion of the heated air is supplied from the outside of the atmospheric inlet, and the remaining portion of the heated air is directly supplied to the inside of the atmospheric inlet, (c) A method of directly supplying the heated air to the inside of the atmospheric air intake port while taking in atmospheric air from the atmospheric air intake port.

5. The urea granulation method according to claim 4, wherein: When the method of supplying heated air having a temperature higher than the ambient temperature in addition to the ambient temperature is method (a) or (b), the method is any one of the following methods: (ab-1) When the heated air is supplied from outside the atmospheric air intake, the heated air is supplied from a plurality of positions facing the plurality of atmospheric air intakes. (ab-2) When supplying the heated air to the atmospheric air inlet, the heated air is supplied from a plurality of positions between the plurality of atmospheric air inlets outside the urea granulation tower toward the atmospheric air inlets on both sides.

6. The method for granulating urea according to any one of claims 1 to 3, wherein When heated air having a temperature higher than the ambient temperature is supplied in addition to the ambient air at the ambient temperature, the ambient air at the ambient temperature is heated by a heater or a heat exchanger before being supplied.

7. The method for granulating urea according to any one of claims 1 to 3, wherein The first requirement that the temperature of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40° C. or higher is satisfied, or The second requirement of the moisture content of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 0.3% or less is satisfied, or satisfying both the first requirement and the second requirement; The water content is measured by using a Karl Fischer titrator or by heating the analysis sample in a desiccator and measuring the loss on drying.

8. A urea granulation device comprising a urea granulation tower and a heated air supply device. The urea granulation tower has an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The molten urea spraying section is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery section is arranged at the bottom of the tower below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction. The heated air supply device includes a heated air production portion and a heated air supply line for supplying the heated air produced by the heated air production portion into the urea granulation tower.

9. A urea granulation device comprising a urea granulation tower and a heated air supply device. The urea granulation tower has an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The molten urea spraying section is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery section is arranged at the bottom of the tower below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction. The plurality of air intake ports are respectively provided with an adjusting member for adjusting the inflow amount and inflow direction of the atmosphere, and the inflow amount from the air intake port, the inflow direction from the air intake port to the interior, or both the inflow amount and the inflow direction are adjusted by increasing or decreasing the opening area of the air intake port using the adjusting member. The heated air supply device includes a heated air production section and a heated air supply line for supplying the heated air produced by the heated air production section into the urea granulation tower from the atmospheric air intake.

10. A urea granulation device comprising a urea granulation tower and a heated air supply device. The urea granulation tower has an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The molten urea spraying section is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery section is arranged at the bottom of the tower below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction. The plurality of air intake ports are respectively provided with adjustment members for the inflow amount and inflow direction of the air. The inflow amount and inflow direction adjusting member is a Venetian blind composed of a set of a freely rotatable rotating shaft and blades fixed to the rotating shaft, and a combination of these sets. In the rotating shaft, both ends of the rotating shaft are rotatably mounted at two opposite positions of the atmosphere inlet, and by rotating the rotating shaft, the angle between the atmosphere inlet surface and the blade plate surface changes between 0 degrees and 90 degrees, thereby adjusting the inflow amount from the atmosphere inlet, the inflow direction from the atmosphere inlet to the interior, or both the inflow amount and the inflow direction. The heated air supply device includes a heated air production section and a heated air supply line for supplying the heated air produced by the heated air production section into the urea granulation tower from the atmospheric air intake.

11. A urea granulation device comprising a urea granulation tower and a heated air supply device. The urea granulation tower has an exhaust port provided at the top of the tower, a spraying portion for molten urea, a plurality of air intake ports, and a recovery portion for granulated urea particles. The molten urea spraying section is arranged on the upper side of the urea granulation tower, the plurality of air intakes are arranged on the lower side of the urea granulation tower, the recovery section is arranged at the bottom of the tower below the air intake, and the plurality of air intakes are arranged at intervals in the circumferential direction. The plurality of air intake ports are respectively provided with adjustment members for the inflow amount and inflow direction of the air. The regulating member for the inflow amount and inflow direction is a gate installed on the upper end, lower end or other part of the atmosphere intake port, which can reduce or increase the opening area of the atmosphere intake port. By reducing or increasing the opening area of the atmosphere intake port using the shutter, the inflow amount from the atmosphere intake port, the inflow direction into the interior, or both the inflow amount and the inflow direction are adjusted. The heated air supply device includes a heated air production section and a heated air supply line for supplying the heated air produced by the heated air production section into the urea granulation tower from the atmospheric air intake.

12. The urea granulation device according to any one of claims 8 to 11, wherein: In the urea granulation tower and the heated air supply device, the heated air exhaust port of the heated air production section is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is arranged opposite to or directly connected to the multiple atmospheric air inlets of the urea granulation tower at intervals.

13. The urea granulation device according to any one of claims 8 to 11, wherein: In the urea granulation tower and the heated air supply device, the heated air outlet of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to the multiple atmospheric inlets of the urea granulation tower. The second end opening of the heated air supply line is a branch pipe branched into a plurality of branches, and has any one of the following modes: A first embodiment: the openings of the plurality of branch pipes are arranged to face the plurality of air intake ports. The second embodiment: the openings of the plurality of branch pipes are directly connected to the plurality of air intake ports. The third aspect includes both the first aspect and the second aspect.

14. The urea granulation device according to any one of claims 8 to 11, wherein: In the urea granulation tower and the heated air supply device, the heated air outlet of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to the multiple atmospheric inlets of the urea granulation tower. The second end opening of the heated air supply line includes an annular portion through which heated air flows and a plurality of hollow columnar portions spaced apart in a circumferential direction of the annular portion and vertically arranged so as to allow air to flow through the annular portion, a portion of the hollow columnar portions having a slit-shaped opening, or a portion of the hollow columnar portions having a plurality of pore groups. The plurality of air intake ports and the plurality of hollow columnar portions having the slit-shaped openings or the plurality of pore groups may be selected from the following first, second, and third aspects: The first mode is that the plurality of air intake ports are located inside, the plurality of hollow columns are located outside, and the slit-shaped openings or the plurality of pore groups of the plurality of hollow columns are arranged opposite to the plurality of air intake ports. The second mode is that the plurality of hollow columns having the slit-shaped openings or the plurality of pore groups are directly connected to the plurality of air intake ports. A third aspect: the plurality of air intake ports and the plurality of hollow columnar portions having the slit-shaped openings or the plurality of pore groups include both the first aspect and the second aspect; Furthermore, when the first to third aspects are viewed from outside, the plurality of inner air intakes are arranged to overlap the plurality of outer hollow columns, and the slit-shaped openings or the plurality of pore groups of the hollow columns are located within the range of the air intakes.

15. The urea granulation device according to any one of claims 8 to 11, wherein: In the urea granulation tower and the heated air supply device, the heated air outlet of the heated air production unit is connected to the first end opening of the heated air supply pipeline, and the second end opening of the heated air supply pipeline is connected to the multiple atmospheric inlets of the urea granulation tower. The second end opening of the heated air supply line comprises an annular portion for the heated air to flow and a plurality of hollow columnar portions arranged at intervals in the circumferential direction of the annular portion and provided perpendicularly from the annular portion, and a plurality of slit-shaped openings or a plurality of pore groups formed along the longitudinal direction at two different positions of the hollow columnar portion. The plurality of air intake ports and the plurality of hollow columns having the slit-shaped openings or the plurality of pore groups have a first configuration, that is, between adjacent ones of the plurality of air intake ports, the slit-shaped openings or the plurality of pore groups formed at two different positions of the plurality of hollow columns are respectively configured to be able to release heated air toward the adjacent air intake ports, Furthermore, as needed, on the basis of the first embodiment, the following second embodiment or third embodiment is also provided: The second embodiment: the second hollow column is directly connected to the atmosphere inlet, the second hollow column is branched from a plurality of hollow columns having the slit-shaped opening or a plurality of pore groups, extends in a direction along the annular portion and has an opening, The third mode is to have a plurality of third hollow columns, each of which has an opening perpendicularly arranged from the annular portion, and the opening of the third hollow column is directly connected to the atmosphere inlet. In both the second and third aspects, heated air is released from the lower side of the plurality of atmosphere intake ports. Furthermore, the inflow amount and inflow direction regulators of the adjacent atmosphere intake ports are adjusted so that the heated air released from the slit-shaped openings or the plurality of pore groups formed at two different positions in the plurality of hollow columns can flow into the interior.

16. The urea granulation device according to any one of claims 8 to 11, wherein: The heated air producing section of the heated air supply device includes a heater or a heat exchanger for heating the taken-in air and a blower for blowing the heated air.

17. The urea granulation device according to any one of claims 8 to 11, wherein: The urea granulation device is any one selected from the following (A) to (D): (A) A urea granulation device comprising a urea granulation tower and a heated air supply device, (B) a urea granulation device comprising a urea granulation tower and a plurality of heated air supply devices, (C) a urea granulation device comprising a plurality of urea granulation towers and a heated air supply device, (D) A urea granulation apparatus including a combination of a plurality of urea granulation towers and a plurality of heated air supply devices.

18. The urea granulation device according to any one of claims 8 to 11, wherein: The ambient temperature around the urea granulation tower, i.e., the temperature at the highest ambient temperature, is used as the assumed maximum temperature in the design of the urea granulation tower. When the ambient temperature around the urea granulation tower is lower than the assumed maximum temperature, in addition to supplying air at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the inside of the urea granulation tower.

19. The urea granulation device according to any one of claims 8 to 11, wherein: The ambient temperature of the environment in which the urea granulation tower is installed, that is, the temperature at which the ambient temperature is the highest, is used as the assumed maximum temperature in the design of the urea granulation tower. When the ambient temperature in which the urea granulation tower is installed is lower than the assumed maximum temperature, in addition to supplying air at the ambient temperature, heated air having a temperature higher than the ambient temperature is also supplied, thereby heating the interior of the urea granulation tower. When the operating load rate in the urea granulation tower is a value Lx expressed in percentage that is lower than the maximum value Lmax expressed in percentage, the greater the difference between Lmax and Lx expressed in percentage, the more the supply amount of heated air can be increased. The operation load rate is a percentage of the average urea granule production amount in a certain period relative to the maximum urea granule production amount in the same period.

20. The urea granulation device according to any one of claims 8 to 11, wherein: The first requirement that the temperature of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 40° C. or higher is satisfied, or The second requirement of the moisture content of the urea particles immediately after being recovered from the recovery section of the urea granulation tower is 0.3% or less is satisfied, or satisfying both the first requirement and the second requirement; The water content is measured by using a Karl Fischer titrator or by heating the analysis sample in a desiccator and measuring the loss on drying.

21. The urea granulation device according to any one of claims 8 to 11, wherein: The urea granulation tower does not include an acid cleaning device for treating exhaust gas from an exhaust port provided at the tower top of the urea granulation tower.

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