An ammonia removal system for a urea granulation tower

Abstract

The present invention provides an ammonia removal system for a urea granulation tower, which includes a hydrogen chloride gas spray head for spraying hydrogen chloride gas below the dust removal cloth bag of the urea granulation tower. During operation, on the one hand, the hydrogen chloride gas can act as a reactant to react with ammonia mixed in the air to form ammonium chloride, and the formed ammonium chloride is intercepted by the dust removal cloth bag, thereby achieving the purpose of ammonia removal; on the other hand, the hydrogen chloride gas can act as a catalyst to cause the tiny urea particles carried in the air to react with the moisture in the air under its catalytic action to form carbon dioxide and ammonia, thereby reducing the air humidity and solving the problem of the dust removal cloth bag being blocked. This ammonia removal system can not only achieve the purpose of ammonia removal, but also reduce the air humidity to solve the problem of the dust removal cloth bag being blocked, so it can be used in combination with the dust removal cloth bag.

Description

Technical Field

[0001] The present invention relates to the technical field of urea granulation, and particularly to an ammonia removal system for a urea granulation tower. Background Art

[0002] A urea granulation tower is a device for preparing granular urea, including a tower body, a granulation nozzle disposed inside the tower body, and an induced draft fan disposed at the top of the tower body. An air inlet is formed at the bottom of the tower body. During preparation, under the action of the induced draft fan, air enters the tower body and flows upward. The granulation nozzle sprays molten urea droplets downward. During the falling process of the molten urea droplets, they contact and exchange heat with the upward flowing air, thereby cooling and solidifying into granular urea.

[0003] During the preparation of granular urea, tiny urea particles will flow with the air. Therefore, dust removal is required before the air is discharged to prevent tiny urea particles from being discharged with the air and polluting the environment. In the past, water washing dust removal was used, but the dust removal effect of water washing dust removal was not ideal, and currently, bag filters are gradually used for dust removal.

[0004] During the preparation of granular urea, ammonia gas will escape. Therefore, ammonia removal is also required before the air is discharged to prevent ammonia gas from being discharged with the air and polluting the environment. Since ammonia gas is soluble in water, in the past, the purpose of water washing ammonia removal could be achieved simultaneously during water washing dust removal. However, after changing to using a bag filter for dust removal, if water washing ammonia removal is still used, it will cause the bag filter to be clogged. Therefore, the water washing ammonia removal system cannot be used together with the bag filter.

[0005] Therefore, developing a new type of ammonia removal system that can be used together with the bag filter without causing the bag filter to be clogged is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides an ammonia removal system for a urea granulation tower, including a hydrogen chloride gas nozzle for spraying hydrogen chloride gas below the dust removal bag of the urea granulation tower.

[0007] During operation, on the one hand, hydrogen chloride gas can act as a reactant to react with ammonia gas mixed in the air to form ammonium chloride, and the formed ammonium chloride is intercepted by the dust removal bag, thereby achieving the purpose of ammonia removal; on the other hand, hydrogen chloride gas can act as a catalyst to cause the tiny urea particles carried in the air to hydrolyze (i.e., react with the moisture in the air) under its catalytic action to generate carbon dioxide and ammonia gas, thereby reducing the air humidity and solving the problem of the bag filter being clogged. The ammonia gas generated by the hydrolysis of the tiny urea particles will also react with hydrogen chloride gas to form ammonium chloride and then be intercepted by the dust removal bag.

[0008] It can be seen that by injecting hydrogen chloride gas below the dust removal cloth bag, the purpose of ammonia removal can be achieved, the air humidity can be reduced, and the problem of the dust removal cloth bag being clogged can be solved. Moreover, the reaction product of ammonia gas and hydrogen chloride gas is simple (only ammonium chloride), so no secondary pollutants will be generated.

[0009] For the ammonia removal system of the urea granulation tower as described above, the hydrogen chloride gas spray head is arranged inside the tower body of the urea granulation tower and is located between the dust removal cloth bag and the granulation spray head of the urea granulation tower.

[0010] For the ammonia removal system of the urea granulation tower as described above, a trough-shaped mounting frame is provided below the dust removal cloth bag. The trough-shaped mounting frame is provided with a downwardly concave groove, and the side wall of the groove is provided with a flow-through hole. Both the granulation spray head and the hydrogen chloride gas spray head are installed on the bottom wall of the groove.

[0011] For the ammonia removal system of the urea granulation tower as described above, the granulation spray head is installed in the middle of the bottom wall of the groove, and the hydrogen chloride gas spray head is arranged around the granulation spray head.

[0012] For the ammonia removal system of the urea granulation tower as described above, the spray orifice of the hydrogen chloride gas spray head faces downward to spray hydrogen chloride gas downward.

[0013] For the ammonia removal system of the urea granulation tower as described above, an induced draft fan is provided at the top of the tower body of the urea granulation tower, and an air inlet is provided at the bottom of the tower body of the urea granulation tower. A flow equalizing plate is provided at the position of the air inlet. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of a specific embodiment of the ammonia removal system of the urea granulation tower provided by the present invention.

[0015] The description of the reference numerals in the drawings is as follows:

[0016] 1 Tower body, 2 Induced draft fan, 3 Air inlet, 4 Flow equalizing plate, 5 Granulation spray head, 6 Hydrogen chloride gas spray head, 7 Dust removal cloth bag, 8 Ceiling plate, 9 Trough-shaped mounting frame, 91 Bottom wall of the groove, 92 Side wall of the groove. Detailed Embodiments

[0017] In order to enable those skilled in the art of the present technology to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0018] Please refer to Figure 1 , Figure 1 It is a schematic diagram of a specific embodiment of the ammonia removal system of the urea granulation tower provided by the present invention.

[0019] As Figure 1As shown in the figure, an induced draft fan 2 is provided at the top of the tower body 1 of the urea granulation tower. An air inlet 3 is formed at the bottom of the tower body 1. During operation, air enters the tower body 1 from the air inlet 3 under the action of the induced draft fan 2 and flows upward from bottom to top. In the illustrated specific embodiment, a flow equalizing plate 4 is provided at the position of the air inlet 3 to enable the air to enter the tower body 1 evenly.

[0020] A granulation spray head 5 is provided inside the tower body 1 of the urea granulation tower. During operation, the granulation spray head 5 sprays molten urea droplets downward. During the falling process of the molten urea droplets, they contact and exchange heat with the upward flowing air, thereby cooling and solidifying into granular urea.

[0021] A perforated plate 8 and dust removal filter bags 7 are also provided inside the urea granulation tower. The dust removal filter bags 7 are installed on the perforated plate 8 and are located below the perforated plate 8 and above the granulation spray head 5. During operation, the air first contacts the molten urea droplets and then flows through the dust removal filter bags 7, so that the tiny urea particles carried in the air are intercepted by the dust removal filter bags 7, thereby achieving the purpose of dust removal.

[0022] Before the air is discharged, in addition to removing the mixed tiny urea particles, the mixed ammonia gas also needs to be removed. For this reason, a hydrogen chloride gas spray head 6 is also provided inside the urea granulation tower.

[0023] During operation, on the one hand, hydrogen chloride gas can act as a reactant and react with the ammonia gas mixed in the air to form ammonium chloride. The formed ammonium chloride is intercepted by the dust removal filter bags 7, thereby achieving the purpose of ammonia removal; on the other hand, hydrogen chloride gas can act as a catalyst to cause the tiny urea particles carried in the air to hydrolyze (i.e., react with the moisture in the air) to generate carbon dioxide and ammonia gas, thereby being able to reduce the air humidity and thus solve the problem of the dust removal filter bags 7 being clogged. The ammonia gas generated by the hydrolysis of the tiny urea particles will also react with hydrogen chloride gas to form ammonium chloride and then be intercepted by the dust removal filter bags 7.

[0024] It can be seen that by spraying hydrogen chloride gas below the dust removal filter bags 7, the purpose of ammonia removal can be achieved, the air humidity can be reduced to solve the problem of the dust removal filter bags 7 being clogged, and the reaction product of ammonia gas and hydrogen chloride gas is simple (only ammonium chloride), so no secondary pollutants will be generated.

[0025] In addition, it should be noted that since acidic substances are also a kind of pollutant, it is generally believed in the industry that when using acidic substances to remove ammonia, if the dosage of acidic substances is too much, acidic substances will be mixed in the emissions, causing secondary pollution. Therefore, acidic substances are basically not used to remove ammonia in the industry.

[0026] The inventors of the present application have found that although hydrogen chloride gas is an acidic substance, since it can not only react with ammonia as a reactant but also catalyze the hydrolysis of tiny urea particles as a catalyst, even when a relatively large amount of hydrogen chloride gas is added, it can be completely consumed as a catalyst without being mixed in the air and discharged to pollute the environment. Therefore, the present application overcomes the technical prejudice in the industry.

[0027] In the illustrated specific embodiment, the hydrogen chloride gas nozzle 6 is arranged inside the tower body 1 of the urea granulation tower and is located between the dust removal cloth bag 7 and the granulation nozzle 5 of the urea granulation tower. Such an arrangement can avoid the risk that the falling molten urea droplets react with the hydrogen chloride gas and affect the preparation of granular urea.

[0028] In the illustrated specific embodiment, a trough-shaped mounting frame 9 is provided below the dust removal cloth bag 7. The trough-shaped mounting frame 9 is provided with a downwardly concave groove. Through holes are provided on the side wall 92 of the groove. Both the granulation nozzle 5 and the hydrogen chloride gas nozzle 6 are installed on the bottom wall 91 of the groove. With such an arrangement, as shown by the arrow in the figure, air can first flow to the bottom wall 91 of the groove, so that it can first contact the hydrogen chloride gas, and then turn and flow through the side wall 92 of the groove to the dust removal cloth bag 7. That is to say, with such an arrangement, it can play a guiding role for the air.

[0029] In the illustrated specific embodiment, the granulation nozzle 5 is installed in the middle of the bottom wall 91 of the groove, and the hydrogen chloride gas nozzle 6 is arranged around the granulation nozzle 5. In this way, it is beneficial to ensure the ammonia removal effect. In the figure, multiple groups of hydrogen chloride gas nozzles 6 are provided, and each group is arranged on different concentric circumferences around the granulation nozzle 5. In actual implementation, the number of the hydrogen chloride gas nozzles 6 can be flexibly set according to the diameter of the tower body 1 of the urea granulation tower. In actual implementation, the arrangement mode of the hydrogen chloride gas nozzles 6 is not limited to that shown in the figure, and it is only necessary to ensure that the hydrogen chloride gas nozzles 6 are evenly distributed on the cross section of the tower body 1 of the urea granulation tower.

[0030] In the illustrated specific embodiment, the nozzle of the hydrogen chloride gas nozzle 6 faces downward to spray hydrogen chloride gas downward. In this way, the ammonia mixed in the air flows upward from bottom to top and counterflows with the hydrogen chloride gas, which is beneficial to ensuring the ammonia removal effect.

[0031] The above has introduced in detail an ammonia removal system for a urea granulation tower provided by the present invention. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An ammonia removal system for a urea granulation tower, characterized in that, It includes a hydrogen chloride gas spray head (6) which is used to spray hydrogen chloride gas below the dust removal cloth bag (7) of the urea granulation tower; At the top of the tower body (1) of the urea granulation tower, there is an induced draft fan (2), and at the bottom of the tower body (1) of the urea granulation tower, there is an air inlet (3); The hydrogen chloride gas spray head (6) is arranged inside the tower body (1) of the urea granulation tower and is located between the dust removal cloth bag (7) of the urea granulation tower and the granulation spray head (5) inside the tower body (1) of the urea granulation tower. During operation, the granulation spray head (5) sprays molten urea droplets downward; Below the dust removal cloth bag (7), there is a trough-shaped mounting frame (9). The trough-shaped mounting frame (9) has a downwardly concave groove. The side wall (92) of the groove is provided with flow-through holes, and both the granulation spray head (5) and the hydrogen chloride gas spray head (6) are installed on the bottom wall (91) of the groove.

2. The ammonia removal system of the urea granulation tower according to claim 1, characterized in that, The granulation spray head (5) is installed in the middle of the bottom wall (91) of the groove, and the hydrogen chloride gas spray head (6) is arranged around the granulation spray head (5).

3. The ammonia removal system of the urea granulation tower according to claim 1, characterized in that The nozzle of the hydrogen chloride gas spray head (6) faces downward to spray hydrogen chloride gas downward.

4. The ammonia removal system of the urea granulation tower according to any one of claims 1-3, characterized in that, A flow equalizing plate (4) is provided at the position of the air inlet (3).

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