A device for reducing the ammonia content in urea venting exhaust gas

Abstract

This utility model relates to the field of urea production technology, and in particular to a device for reducing the ammonia content in urea vent gas. The device comprises: an atmospheric pressure absorption tower, a low-pressure absorption tower, a reabsorption tower, a venting cylinder, and a mixing tank. An atmospheric pressure output pipe is fixedly connected to the top of the atmospheric pressure absorption tower, a low-pressure output pipe is fixedly connected to the top of the low-pressure absorption tower, a two-way pipe is fixedly connected to one side of the reabsorption tower, a venting pipe is fixedly connected to the top of the reabsorption tower, and a carbon dioxide input pipe is installed at the bottom of the reabsorption tower. The device for reducing the ammonia content in urea vent gas provided by this utility model effectively reduces the ammonia content in the vent gas, reduces environmental pollution, and minimizes secondary pollution. Furthermore, it can improve efficiency, reduce system energy consumption, save production costs, facilitate the removal of impurities adhering to the packing layer, and ensure the mass transfer effect of the packing layer.

Description

Technical Field

[0001] This utility model relates to the field of urea production technology, and in particular to a device for reducing the ammonia content in urea venting exhaust gas. Background Technology

[0002] Urea, chemically known as carbodiamine, is an organic compound containing approximately 46% nitrogen. It is a white crystal or powder at room temperature, easily soluble in water, and has no obvious odor. However, in the CO2 stripping process for urea production, the exhaust gas from the urea plant has a high ammonia content. This results in the emission of waste gas, wastewater, and solid waste, which pollutes the environment. Furthermore, it increases system consumption, raises production costs, and reduces economic efficiency.

[0003] Currently, most exhaust gas venting pipes release ammonia from two main sources: the ammonia in the low-pressure absorption tower entering the venting pipe and the ammonia in the inert gas emitted from the high-pressure absorption tower. The venting pipes release the ammonia directly into the atmosphere without treatment, causing environmental pollution.

[0004] Therefore, it is necessary to provide a new device for reducing the ammonia content in urea venting exhaust gas to solve the above-mentioned technical problems. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a device for reducing the ammonia content in urea venting exhaust gas.

[0006] The device for reducing ammonia content in urea venting exhaust gas provided by this utility model includes: an atmospheric pressure absorption tower, a low-pressure absorption tower, a reabsorption tower, a venting cylinder, and a mixing tank. An atmospheric pressure output pipe is fixedly connected to the top of the atmospheric pressure absorption tower, a low-pressure output pipe is fixedly connected to the top of the low-pressure absorption tower, a two-way pipe is fixedly connected to one side of the reabsorption tower, a venting pipe is fixedly connected to the top of the reabsorption tower, a carbon dioxide input pipe is installed at the bottom of the reabsorption tower, a slag discharge assembly is installed at the axial center of the bottom of the reabsorption tower, and three [unclear - possibly referring to components or components] are installed on the inner wall of the reabsorption tower from top to bottom. An inclined pipe is fixedly connected to the bottom of the packing layer and the reabsorption tower away from the axis. A circulation pump is installed at the end of the inclined pipe away from the reabsorption tower. A transmission pipe is fixedly connected to the end of the circulation pump away from the inclined pipe. Three output ends are provided on the transmission pipe, and each output end is fixedly connected to a fixed pipe. A gathering hood is fixedly connected to the end of the fixed pipe away from the transmission pipe. Multiple high-pressure cleaning nozzles are fixedly connected to the bottom of the gathering hood. Multiple spray nozzles are fixedly connected to the bottom of the gathering hood. A water pump is installed on the outside of the mixing tank. A water pipe is fixedly connected to the output end of the water pump.

[0007] Preferably, the slag discharge assembly includes a slag discharge pipe, the top end of which is fixedly connected to the bottom axis of the reabsorption tower, and an electric gate valve is installed on the slag discharge pipe.

[0008] Preferably, the end of the atmospheric pressure output pipe furthest from the atmospheric pressure absorption tower is fixedly connected to one end of the two-way pipe, and the end furthest from the low pressure absorption tower is fixedly connected to the other end of the two-way pipe.

[0009] Preferably, the end of the vent pipe furthest from the reabsorption tower is fixedly connected to the inlet end of the vent cylinder.

[0010] Preferably, the lower packing layer is made of metal stepped ring packing with a height of 1.2m, the middle packing layer is made of plastic conjugate ring packing with a height of 1.5m, and the upper packing layer is made of metal wire mesh corrugated packing with a height of 0.8m.

[0011] Preferably, a portion of the outer side of the fixed pipe is fixedly connected to the inner wall of one side of the reabsorption tower, and the end of the water pipe away from the water pump is fixedly connected to the outer side of the transmission pipe.

[0012] Preferably, when cleaning of the packing layer is required, demineralized water is added to the mixing tank and then transferred to the high-pressure cleaning nozzle to rinse the packing; during normal operation, dilute sulfuric acid and demineralized water are added to the mixing tank for mixing and then sprayed using the spray nozzle.

[0013] Compared with related technologies, the device for reducing the ammonia content in urea venting exhaust gas provided by this utility model has the following beneficial effects: This invention utilizes the packing layer within the reabsorption tower and the absorbent liquid, a mixture of dilute sulfuric acid and demineralized water, to achieve full contact with the exhaust gas, significantly improving ammonia absorption efficiency, effectively reducing the ammonia content in the vented exhaust gas, minimizing environmental pollution, and minimizing secondary pollution. Furthermore, it can tap potential and increase efficiency, reduce system energy consumption, and save production costs.

[0014] This invention features a high-pressure cleaning nozzle. When the packing layer needs cleaning, it can be rinsed with demineralized water to easily remove impurities adhering to the packing layer, ensuring the mass transfer effect of the packing layer, reducing the problem of decreased absorption efficiency due to impurity accumulation, and lowering the difficulty and cost of equipment maintenance. Attached Figure Description

[0015] Figure 1 A schematic diagram of the device for reducing the ammonia content in urea venting exhaust gas provided by this utility model; Figure 2 for Figure 1 The diagram shown is a structural schematic of the reabsorption tower. Figure 3 for Figure 1 The diagram shows the structure of the fixed tube. Figure 4 for Figure 3 The diagram shows the structure of the gathering cover.

[0016] The diagram is labeled as follows: 1. Atmospheric pressure absorption tower; 101. Atmospheric pressure output pipe; 2. Low pressure absorption tower; 201. Low pressure output pipe; 3. Reabsorption tower; 301. Two-way pipe; 302. Vent pipe; 303. Carbon dioxide input pipe; 4. Vent cylinder; 5. Slag discharge pipe; 6. Electric gate valve; 7. Packing layer; 8. Inclined pipe; 9. Circulating pump; 10. Transfer pipe; 11. Fixed pipe; 12. Gathering hood; 13. High-pressure cleaning nozzle; 14. Spray head; 15. Mixing tank; 16. Water pump; 17. Water pipe. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0018] The specific implementation of this utility model will be described in detail below with reference to specific embodiments. Please see Figures 1 to 4 A device for reducing the ammonia content in urea venting exhaust gas includes: an atmospheric pressure absorption tower 1, a low-pressure absorption tower 2, a reabsorption tower 3, a venting cylinder 4, and a mixing tank 15. An atmospheric pressure output pipe 101 is fixedly connected to the top of the atmospheric pressure absorption tower 1, which is responsible for conveying the gas treated by the atmospheric pressure absorption tower 1. A low-pressure output pipe 201 is fixedly connected to the top of the low-pressure absorption tower 2 for conveying the gas treated by the low-pressure absorption tower 2. A two-way pipe 301 is fixedly connected to one side of the reabsorption tower 3. The end of the atmospheric pressure output pipe 101 away from the atmospheric pressure absorption tower 1 is fixedly connected to one end of the two-way pipe 301. The end of the low-pressure output pipe 201 away from the low-pressure absorption tower 2 is fixedly connected to the two-way pipe 301. The other end of pipe 301 is fixedly connected. This connection allows the gases from the atmospheric pressure and low pressure absorption towers to converge into the two-way pipe 301 and enter the reabsorption tower 3 together. The top of the reabsorption tower 3 is fixedly connected to a vent pipe 302. The end of the vent pipe 302 away from the reabsorption tower 3 is fixedly connected to the input end of the vent cylinder 4. The exhaust gas after being treated by the reabsorption tower 3 can be transported to the vent cylinder 4 through the vent pipe 302 and finally discharged into the atmosphere. A carbon dioxide input pipe 303 is installed at the bottom of the reabsorption tower 3. The carbon dioxide input pipe 303 can introduce carbon dioxide gas into the reabsorption tower 3 to create an acidic environment inside the tower, which helps to absorb alkaline ammonia substances.

[0019] The slag discharge assembly is installed at the bottom axis of the reabsorption tower 3. The slag discharge assembly includes a slag discharge pipe 5. The top end of the slag discharge pipe 5 is fixedly connected to the bottom axis of the reabsorption tower 3. An electric gate valve 6 is installed on the slag discharge pipe 5. When it is necessary to discharge the waste residue at the bottom of the reabsorption tower 3, the electric gate valve 6 is opened, and the waste residue can be discharged through the slag discharge pipe 5, thereby ensuring the cleanliness of the inside of the reabsorption tower 3.

[0020] The inner wall of the reabsorption tower 3 is equipped with three packing layers 7 from top to bottom. The lower packing layer 7 uses metal stepped ring packing with a height of 1.2m. The metal stepped ring packing has a large specific surface area and porosity, which can provide sufficient space for gas-liquid contact and improve mass transfer efficiency. The middle packing layer 7 uses plastic conjugate ring packing with a height of 1.5m. The plastic conjugate ring packing not only has good corrosion resistance, but also enhances the turbulence of gas and liquid, further promoting ammonia absorption. The upper packing layer 7 uses metal wire mesh corrugated packing with a height of 0.8m. The metal wire mesh corrugated packing has high mass transfer efficiency and can deeply absorb ammonia in the tail gas. An inclined pipe 8 is fixedly connected to the bottom of the reabsorption tower 3 away from the axis. The inclined design of the inclined pipe 8 is conducive to the flow and collection of the absorbent liquid. A circulation pump 9 is installed at the end of the inclined pipe 8 away from the reabsorption tower 3. The circulation pump 9 provides power to transport the absorbent liquid. A transmission pipe 10 is fixedly connected to the end away from the inclined pipe 8. The transmission pipe 10 has three output ends, and each output end is fixedly connected to a fixed pipe 11. A portion of the outer side of the fixed pipe 11 is fixedly connected to the inner wall of one side of the reabsorption tower 3, which serves to fix and support the fixed pipe 11. A gathering hood 12 is fixedly connected to the end of the fixed pipe 11 away from the transmission pipe 10. The gathering hood 12 can gather the liquid transported from the fixed pipe 11, which is convenient for subsequent spraying or cleaning operations. Multiple high-pressure cleaning nozzles 13 are fixedly connected to the bottom end of the gathering hood 12. When it is necessary to clean the packing layer 7, the high-pressure cleaning nozzles 13 can spray high-pressure water to wash away the impurities attached to the packing layer 7. Multiple spray nozzles 14 are fixedly connected to the bottom end of the gathering hood 12. During normal ammonia absorption, the spray nozzles 14 can spray the absorbent liquid evenly onto the packing layer 7, so that the absorbent liquid and the tail gas can fully contact each other and improve the ammonia absorption rate.

[0021] A water pump 16 is installed on the outside of the mixing tank 15. When it is necessary to clean the packing layer 7, demineralized water is added to the mixing tank 15, the water pump 16 is started, and the demineralized water flows and is then transmitted to the high-pressure cleaning nozzle 13 to rinse the packing. During normal operation, dilute sulfuric acid and demineralized water are added to the mixing tank 15 and mixed. The mixed solution forms an acidic absorbent. Then the water pump 16 works, and the mixed solution flows and is sprayed by the spray nozzle 14, so that the absorbent reacts with the ammonia in the exhaust gas, thereby absorbing the ammonia. The output end of the water pump 16 is fixedly connected to a water pipe 17. The end of the water pipe 17 away from the water pump 16 is fixedly connected to the outside of the transmission pipe 10. This connection allows the liquid transported by the water pump 16 to enter the transmission pipe 10 through the water pipe 17 and then be transported to each fixed pipe 11.

[0022] The working principle of the device for reducing the ammonia content in urea venting exhaust gas provided by this utility model is as follows: In the process of reducing the ammonia content in the urea venting tail gas, firstly, the atmospheric pressure absorption tower 1 operates, and its top atmospheric pressure output pipe 101 begins to transport the treated gas. At the same time, the low pressure absorption tower 2 also starts, and its top low pressure output pipe 201 also transmits the corresponding gas. These gases enter the reabsorption tower 3 together through the two-way pipe 301. Then, carbon dioxide gas is introduced into the carbon dioxide input pipe 303 at the bottom of the reabsorption tower 3 to create an acidic environment inside the tower, which helps to absorb alkaline ammonia substances. Then, the circulation pump 9 starts to work, driving the absorbent liquid in the inclined pipe 8 to flow. The absorbent liquid passes through the transmission pipe 10 and the fixed pipe 11, so that the gathering hood 12 is ready for subsequent spraying or cleaning operations. When cleaning of the packing layer 7 is required, demineralized water is added to the mixing tank 15, the water pump 16 is started, and the water pipe 17 is driven to transport the demineralized water. The demineralized water reaches the collection hood 12 through the transmission pipe 10 and the fixed pipe 11, which in turn causes the high-pressure cleaning nozzle 13 to spray out the demineralized water to rinse the packing layer 7 in the reabsorption tower 3 and remove the impurities attached to the packing layer 7. When the normal ammonia absorption is carried out, dilute sulfuric acid and demineralized water are added to the mixing tank 15 and mixed. The water pump 16 is started again, and the mixed liquid is driven through the water pipe 17, the transmission pipe 10 and the fixed pipe 11 to reach the collection hood 12, so that the spray nozzle 14 sprays out the mixed liquid, which fully contacts the tail gas in the reabsorption tower 3 to absorb the ammonia in the tail gas. In addition, the slag discharge assembly at the bottom of the reabsorption tower 3 also plays a role. The electric gate valve 6 on the slag discharge pipe 5 is opened or closed as needed. When it is necessary to discharge waste residue and other substances from the bottom of the tower, the electric gate valve 6 is opened, allowing the waste residue to be discharged through the slag discharge pipe 5. After a series of absorption, cleaning and other operations, the treated tail gas is transmitted to the venting cylinder 4 through the venting pipe 302 at the top of the reabsorption tower 3, and finally discharged into the atmosphere from the venting cylinder 4, thereby achieving the purpose of reducing the ammonia content in the urea venting tail gas.

[0023] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A device for reducing the ammonia content in urea vent gas, characterized in that, The utility model relates to a kind of carbon dioxide absorption tower, including: Normal pressure absorption tower (1), low pressure absorption tower (2), reabsorption tower (3), venting cylinder (4), mixing bucket (15), the top of normal pressure absorption tower (1) is fixedly connected with normal pressure output pipe (101), the top of low pressure absorption tower (2) is fixedly connected with low pressure output pipe (201), one side of reabsorption tower (3) is fixedly connected with two-way pipe (301), the top of reabsorption tower (3) is fixedly connected with venting pipe (302), the outside bottom of reabsorption tower (3) is installed with carbon dioxide input pipe (303); Deslagging assembly, the bottom of reabsorption tower (3) is installed with deslagging assembly at the center of shaft; Packing layer (7), the inner wall of reabsorption tower (3) is installed with three packing layers (7) from top to bottom, the bottom of reabsorption tower (3) is fixedly connected with inclined pipe (8) away from the center of shaft, circulating pump (9) is installed at the end of inclined pipe (8) away from reabsorption tower (3), circulating pump (9) is fixedly connected with transmission pipe (10) away from the end of inclined pipe (8), transmission pipe (10) is provided with three output ends, and each output end is fixedly connected with fixed pipe (11), fixed pipe (11) is fixedly connected with converging cover (12) away from the end of transmission pipe (10), converging cover (12) is fixedly connected with multiple high-pressure cleaning nozzles (13) at the bottom, and converging cover (12) is fixedly connected with multiple spray heads (14) at the bottom; Water pump (16), water pump (16) is installed outside mixing bucket (15), and the output end of water pump (16) is fixedly connected with water pipe (17).

2. The apparatus of claim 1, wherein, Deslagging assembly includes deslagging pipe (5), and the top of deslagging pipe (5) is fixedly connected with the center of shaft at the bottom of reabsorption tower (3), and electric gate valve (6) is installed on deslagging pipe (5).

3. The apparatus of claim 1, wherein the ammonia slip catalyst is positioned downstream of the urea synthesis reactor and upstream of the urea recovery unit. Normal pressure output pipe (101) is fixedly connected with one end of two-way pipe (301) away from normal pressure absorption tower (1), and (202) is fixedly connected with the other end of two-way pipe (301) away from low pressure absorption tower (2).

4. The device for reducing the ammonia content in urea vent gas according to claim 1, characterized in that, Venting pipe (302) is fixedly connected with the input end of venting cylinder (4) away from reabsorption tower (3).

5. The apparatus of claim 1, wherein the ammonia slip catalyst is positioned downstream of the urea synthesis reactor and upstream of the urea recovery system. The packing layer (7) in lower layer is selected from metal step ring packing and has a height of 1.2 m, the packing layer (7) in middle layer is selected from plastic conjugate ring packing and has a height of 1.5 m, and the packing layer (7) in upper layer is selected from metal wire mesh corrugated packing and has a height of 0.8 m.

6. The device for reducing the ammonia content in urea vent gas according to claim 1, characterized in that, A part of the outside of fixed pipe (11) is fixedly connected with one side of the inner wall of reabsorption tower (3), and the end of water pipe (17) away from water pump (16) is fixedly connected with the outside of transmission pipe (10).

7. The device for reducing the ammonia content in urea vent gas according to claim 1, characterized in that, When the packing layer (7) needs to be cleaned, desalted water is put into the mixing bucket (15) and then transmitted to the high-pressure cleaning nozzle (13) to flush the packing; when working normally, dilute sulfuric acid and desalted water are put into the mixing bucket (15) for mixing, and then sprayed by the spray head (14).

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