Device for producing ammonium nitrate solution from tail gas based on melamine
By designing a neutralization reactor and a neutralization flash tank, the problem of ineffective utilization of melamine tail gas was solved, and the tail gas was efficiently converted into ammonium nitrate solution, thereby improving economic benefits.
Patent Information
- Application Number
- CN202422945477.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-30
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2034-11-30
AI Technical Summary
In the existing technology, there are great differences in the comprehensive utilization methods of melamine tail gas, and the tail gas cannot be effectively used to produce ammonium nitrate solution, which affects the economic benefits of the triamine unit product.
A device for producing ammonium nitrate solution from melamine-based tail gas is used, including a neutralization reactor and a neutralization flash tank. Through designs such as mixing components, circulating liquid pipelines and anti-vortex baffles, a full neutralization reaction between tail gas and nitric acid is achieved, thereby improving the utilization rate of ammonia.
The complete neutralization reaction of tail gas is achieved, more ammonium nitrate solution is produced stably and economically, production costs are reduced, and the market competitiveness of triamine products is improved.
Smart Images
Figure CN223454019U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of melamine tail gas treatment, in particular to a device for producing ammonium nitrate solution based on melamine tail gas. BACKGROUND
[0002] At present, about 1028-1078 kg of ammonia and about 1137 kg of carbon dioxide are produced in the tail gas for every ton of melamine produced, so the comprehensive utilization of melamine tail gas is an important part of melamine device, and the selection of tail gas treatment method will have an important impact on the comprehensive energy consumption and manufacturing cost of melamine unit product. At present, the market competition is fierce, the comprehensive utilization of melamine tail gas can even determine the market competitiveness of melamine product, which is an important link for the whole melamine industry to improve economic efficiency.
[0003] Generally speaking, there are the following process methods for the recovery of melamine tail gas: 1. Directly returned to the urea production system; 2. Separated by ammonia and carbon and then returned to the urea system; 3. Tail gas co-production of ammonium bicarbonate or carbonated ammonia water; 4. Melamine tail gas production of soda and ammonium chloride; 5. Utilization of melamine tail gas to produce ammonium nitrate.
[0004] From the actual situation of the factory, melamine tail gas co-production of ammonium nitrate is the best choice for tail gas treatment, which has high ammonia gas utilization rate and can realize ammonia and carbon separation without heat and electricity consumption. From the production point of view, it can greatly reduce the production cost and highlight the economic benefit.
[0005] For the related technology in the above, the inventors found that different neutralization technologies have great difference in the production of ammonium nitrate solution, and it is a current problem to adopt a more optimal form of neutralization technology device to better utilize melamine tail gas. CONTENT OF THE INVENTION
[0006] In order to improve the problem of utilization of melamine tail gas, the present application provides a device for producing ammonium nitrate solution based on melamine tail gas.
[0007] The application provides a device for producing an ammonium nitrate solution based on melamine tail gas, which adopts the following technical scheme: a device for producing an ammonium nitrate solution based on melamine tail gas, comprising a neutralization reactor and a neutralization flash tank, the neutralization reactor and the neutralization flash tank being communicated, the neutralization reactor being tubular and arranged transversely, one end of the neutralization reactor being an ammonium nitrate solution inlet and the other end being a reaction liquid outlet, a main tail gas inlet for melamine tail gas being formed on the side wall of the neutralization reactor near the ammonium nitrate solution inlet; a reaction liquid inlet being formed on the side wall of the neutralization flash tank at a position corresponding to the position where the neutralization reactor is communicated, a process steam outlet for steam generated by neutralization heat being formed on the top of the neutralization flash tank, and an ammonium nitrate solution outlet being formed on the bottom of the neutralization flash tank; the neutralization reactor and the neutralization flash tank being communicated along the tangent direction of the inner wall of the neutralization flash tank.
[0008] Preferably, a secondary tail gas inlet is formed on the side wall of the neutralization reactor near the main tail gas inlet.
[0009] Preferably, a mixing assembly is arranged in the neutralization reactor, the mixing assembly comprising a pipe joint and an impeller arranged in the pipe joint, the pipe joint being arranged between the main tail gas inlet and the secondary tail gas inlet on the neutralization reactor.
[0010] Preferably, a flow discharge hole is formed in the center of the impeller, and a flow distribution slot is formed on the outer edge of the impeller along the circumferential direction.
[0011] Preferably, the flow distribution slot is arc-shaped, and the arc directions of all the flow distribution slots are the same; the inlet directions of the main tail gas inlet and the secondary tail gas inlet are consistent with the tangent directions of the arc of the flow distribution slot.
[0012] Preferably, a central flow collection area is arranged on one side of the impeller near the main tail gas inlet, the central flow collection area is an annular area, the inner circle of the annular area is the outer edge of the flow discharge hole, and the outer circle of the annular area is close to one end of the flow distribution slot near the center of the impeller; at the same time, the central flow collection area is recessed towards the inside of the impeller.
[0013] Preferably, the neutralization flash tank comprises a cylinder and a lower head, the reaction liquid inlet is arranged in the middle of the cylinder, and the process steam outlet is arranged on the top of the cylinder; the head and the cylinder are communicated, and the ammonium nitrate solution outlet is arranged on the bottom of the head; a circulating liquid pipeline is further arranged on the cylinder, two ends of the circulating liquid pipeline are a circulating liquid inlet and a circulating liquid outlet, respectively, the circulating liquid inlet is arranged outside the cylinder and is communicated with a circulating pump, the circulating pump is communicated with the ammonium nitrate solution outlet pipeline, the circulating liquid outlet is arranged inside the cylinder and is located lower than the reaction liquid inlet and higher than the ammonium nitrate solution liquid level.
[0014] Preferably, an anti-vortex baffle is arranged in the head, the anti-vortex baffle comprises a flow guide cylinder and a cross-shaped flow distribution plate, the flow guide cylinder is tightly fitted in the head, the axis of the flow guide cylinder is coincident with the axis of the head, the cross-shaped flow distribution plate has a cross-shaped cross section and is vertically fixed inside the flow guide cylinder.
[0015] Preferably, a plurality of baffle plates are fixedly arranged on the cross distribution plate.
[0016] Preferably, a demister is arranged on the top of the neutralization flash tank.
[0017] In summary, the present application has at least one of the following beneficial technical effects:
[0018] 1. Firstly, the melamine tail gas and nitric acid can be more fully neutralized by the neutralization reactor and the neutralization flash tank, and more nitramine solution can be produced stably and economically by better use of the melamine tail gas;
[0019] 2. Secondly, by arranging the mixing assembly, the melamine tail gas and nitric acid are blocked by the impeller after quickly entering the neutralization reactor, and are more effectively mixed and the reaction time is prolonged. After the reaction in this stage, the solution can enter the subsequent stage of the neutralization reactor through the leakage hole and the shunt slit to continue the reaction, so that the neutralization reaction is more sufficient;
[0020] 3. Further, by arranging the circulating liquid pipeline, the circulation pump can make the nitramine solution circulate. The nitric acid in the circulating liquid maintains the solution acidic, and a large amount of ammonia is further absorbed and neutralized in the acidic circulating liquid, so that the neutralization reaction is more thorough. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 is a process flow diagram of the embodiment of the present application;
[0022] Figure 2 is a structural diagram of the neutralization reactor of the embodiment of the present application;
[0023] Figure 3 is a structural diagram of the impeller of the embodiment of the present application;
[0024] Figure 4 is a structural diagram of the neutralization flash tank of the embodiment of the present application;
[0025] Figure 5 is a structural diagram of the vortex-preventing liquid baffle of the embodiment of the present application.
[0026] In the figure, 1, neutralization reactor; 11, nitric acid solution inlet; 12, main tail gas inlet; 13, reaction liquid outlet; 14, mixing assembly; 141, pipe joint; 142, impeller; 1421, discharge hole; 1422, shunt slit; 1423, central collection area; 15, secondary tail gas inlet; 2, neutralization flash tank; 21, cylinder; 211, reaction liquid inlet; 212, process steam outlet; 22, head; 221, ammonium nitrate solution outlet; 222, anti-vortex liquid baffle; 2221, flow guide cylinder; 2222, cross-shaped liquid distribution plate; 2223, rib plate; 23, circulating liquid pipeline; 231, circulating liquid inlet; 232, circulating liquid outlet; 233, circulating pump; 24, demister. DETAILED DESCRIPTION
[0027] The following will be described in detail with reference to the accompanying drawings. Figure 1 - the accompanying drawings Figure 5 The present application will be further described in detail.
[0028] A device for producing ammonium nitrate solution based on melamine tail gas, referring to Figure 1 、 Figure 2 , includes two parts of neutralization reactor 1 and neutralization flash tank 2, and the neutralization reactor 1 and the neutralization flash tank 2 are communicated; the neutralization reactor 1 is tubular and arranged transversely, one end is the ammonium nitrate solution inlet 11 and the other end is the reaction liquid outlet 13, and the main tail gas inlet 12 for melamine tail gas to enter is arranged on the side wall of the neutralization reactor 1 near the ammonium nitrate solution inlet 11; the reaction liquid inlet 211 is arranged on the middle part of the side wall of the neutralization flash tank 2 corresponding to the position where the neutralization reactor 1 is communicated, the process steam outlet 212 for steam generated by neutralization heat to be discharged is arranged on the top of the neutralization flash tank 2, and the ammonium nitrate solution outlet 221 is arranged on the bottom of the neutralization flash tank 2; the neutralization reactor 1 and the neutralization flash tank 2 are communicated along the tangent direction of the inner wall of the neutralization flash tank 2.
[0029] Through the above arrangement, in the production process, the melamine tail gas is filtered to remove the dust in the tail gas, the main component of the dust is melamine, and is sent to the neutralization reactor 1, the dilute nitric acid is also sent to the neutralization reactor 1 through the pipeline, the melamine tail gas and the nitric acid solution enter the neutralization reactor 1 at a certain ratio at the same time, are mixed and react, and release heat to generate steam; the reaction liquid and the steam continue to enter the neutralization flash tank 2, the process steam is separated from the ammonium nitrate solution in the neutralization flash tank 2 through flash evaporation, enters the system steam pipe network through the process steam outlet 212, and the ammonium nitrate solution remains at the bottom of the neutralization flash tank 2, the concentration is generally about 75-80%, and when the ammonium nitrate solution reaches a certain amount, it can be sent to the storage tank or the subsequent washing / concentration process pipeline through the pipeline through the ammonium nitrate solution outlet 221.
[0030] Furthermore, because the neutralization reactor 1 and the neutralization flash tank 2 are connected along the tangential direction of the inner wall of the neutralization flash tank 2, compared with the common vertical connection, the reaction liquid and steam in the present application can enter the neutralization flash tank 2 at a certain ejection speed through the neutralization reactor 1, rotate and spread on the inner wall of the neutralization flash tank 2, have a larger surface area and are more dispersed, so that the reaction liquid and steam can be flash-separated faster.
[0031] A secondary tail gas inlet 15 is provided on the side wall of the neutralization reactor 1, near the main tail gas inlet 12. When the pH value of the subsequent ammonium nitrate solution is detected to be acidic, the secondary tail gas inlet 15 can be opened to replenish the incoming melamine tail gas. A flow valve can also be provided on the secondary tail gas inlet 15 for more accurate regulation.
[0032] Reference Figure 2 、 Figure 3 A mixing assembly 14 is also provided in the neutralization reactor 1 to improve the mixing efficiency of melamine tail gas and nitric acid. The mixing assembly 14 includes a pipe segment 141 and an impeller 142 installed in the pipe segment 141. The diameter of the pipe segment 141 is larger than the diameter of the neutralization reactor 1, and the central axis of the pipe segment 141 coincides with the central axis of the neutralization reactor 1. The pipe segment 141 is fixed to and connected to the neutralization reactor 1 via flanges at both ends. The pipe segment 141 is preferably located between the main tail gas inlet 12 and the secondary tail gas inlet 15. The central axis of the impeller 142 coincides with the central axis of the neutralization reactor 1, and the diameter of the impeller 142 is slightly larger than the inner diameter of the neutralization reactor 1. The impeller 142 fits tightly within the pipe segment 141. A drain hole 1421 is provided in the center of the impeller 142, and diverter slits 1422 are spaced circumferentially on the outer edge.
[0033] Through the above arrangement, the melamine tail gas and nitric acid will be blocked by the impeller 142 after quickly entering the neutralization reactor 1, so as to achieve more effective mixing and extend the reaction time. After the reaction in this stage, they can enter the subsequent stage of the neutralization reactor 1 through the leakage hole 1421 and the diversion seam 1422 to continue the reaction, thereby making the neutralization reaction more complete.
[0034] Furthermore, the diverter slits 1422 are arc-shaped, and all diverter slits 1422 have the same arc direction, i.e., arranged counterclockwise or clockwise. Furthermore, the inlet directions of the exhaust main inlet 12 and the exhaust secondary inlet 15 are aligned with the arc tangent direction of the diverter slits 1422. This arrangement facilitates swirling of the melamine exhaust gas and nitric acid at the impeller 142, resulting in better mixing.
[0035] Further, a central collection area 1423 is arranged on the impeller 142 near the side of the main exhaust gas inlet 12, the central collection area 1423 is an annular area, with the center of the impeller 142 as the center, the annular inner circle is the outer edge of the discharge hole 1421, and the annular outer circle is close to the end of the shunt slit 1422 near the center of the impeller 142; At the same time, the central collection area 1423 is recessed towards the inside of the impeller 142. Through the above arrangement, the melamine exhaust gas and nitric acid can more easily generate a cyclone at the impeller 142, and the reaction can be better carried out in the process of further concentrating into the discharge hole 1421.
[0036] With reference to Figure 1 , Figure 4 The neutralization flash tank 2 includes a cylinder 21 and a lower head 22, the reaction liquid inlet 211 is arranged in the middle of the cylinder 21 and is oval-shaped to better disperse the reaction liquid and steam, and the process steam outlet 212 is arranged at the top of the cylinder 21. The head 22 is in communication with the cylinder 21, and the ammonium nitrate solution outlet 221 is arranged at the bottom of the head 22.
[0037] A circulating liquid pipeline 23 is further arranged on the cylinder 21, and the two ends of the circulating liquid pipeline 23 are respectively the circulating liquid inlet 231 and the circulating liquid outlet 232. The circulating liquid inlet 231 is arranged outside the cylinder 21 and is in communication with the circulating pump 233, and the circulating pump 233 is in communication with the ammonium nitrate solution outlet 221 pipeline; the circulating liquid outlet 232 is arranged inside the cylinder 21 and is lower than the reaction liquid inlet 211 and higher than the ammonium nitrate solution liquid level.
[0038] Through the above arrangement, the circulating pump 233 can circulate the ammonium nitrate solution, and the nitric acid in the circulating liquid can maintain the solution to be acidic, and a large amount of ammonia can be further absorbed and neutralized in the acidic circulating liquid, so that the neutralization reaction is more complete.
[0039] The process steam after flash evaporation also contains a small amount of ammonium nitrate mist, and a mist eliminator 24 is arranged at the position near the process steam outlet 212 at the top of the neutralization flash tank 2; the mist eliminator 24 includes a support and a wire mesh / blade, the support is fixed to the inner wall of the neutralization flash tank 2, and the wire mesh / blade is fixed to the support, so that the mist carried in the process steam can be removed through the wire mesh / blade, the mist droplets of the ammonium nitrate solution are recovered, the separated liquid returns to the neutralization flash tank 2, and the process steam enters the system steam pipeline network.
[0040] With reference to Figure 4 , Figure 5A vortex-preventing baffle 222 is further arranged in the cover 22, and the vortex-preventing baffle 222 comprises a flow guide cylinder 2221 and a cross-shaped liquid distribution plate 2222, the flow guide cylinder 2221 is tightly fitted in the cover 22, the axis of the flow guide cylinder 2221 coincides with the axis of the cover 22, the cross-shaped liquid distribution plate 2222 has a cross-shaped cross section and is vertically fixed to the inside upper side of the flow guide cylinder 2221, and a plurality of baffle plates 2223 are further fixed to the cross-shaped liquid distribution plate 2222 at intervals. Through the above arrangement, the vortex of the ammonium nitrate solution can be prevented, which can prevent the ammonium nitrate solution from being atomized on one hand and can prevent the circulating pump from being steamy on the other hand.
[0041] The implementation principle of the embodiment of the present application is that the melamine tail gas and nitric acid can be more fully neutralized in the neutralization reactor and the neutralization flash tank, the tail gas of melamine can be better utilized, and more stable and economical ammonium nitrate solution can be produced.
[0042] The embodiments of the specific implementation are the preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, wherein the same parts are denoted by the same reference numerals. Therefore, equivalent changes made according to the structure, shape, principle of the present application should be covered in the protection scope of the present application.
Claims
1. A device for producing an ammonium nitrate solution based on melamine off-gas, comprising a neutralization reactor (1) and a neutralization flash tank (2), the neutralization reactor (1) and the neutralization flash tank (2) being in communication, characterized in that, The neutralization reactor (1) is tubular and arranged transversely, with one end being an ammonium nitrate solution inlet and the other end being a reaction liquid outlet (13); a tail gas main inlet (12) for tail gas of melamine is arranged on the side wall of the neutralization reactor (1) near the ammonium nitrate solution inlet; The neutralization flash tank (2) is provided with a reaction liquid inlet (211) in the middle of the side wall and corresponding to the position of the neutralization reactor (1); a process steam outlet (212) for steam generated by neutralization is arranged on the top of the neutralization flash tank (2); and an ammonium nitrate solution outlet (221) is arranged on the bottom of the neutralization flash tank (2); The neutralization reactor (1) and the neutralization flash tank (2) are communicated along the tangential direction of the inner wall of the neutralization flash tank (2).
2. A device for producing an ammonium nitrate solution from a melamine-based exhaust gas according to claim 1, characterized in that The neutralization reactor (1) is provided with a tail gas secondary inlet (15) on the side wall near the tail gas main inlet (12).
3. A device for producing an ammonium nitrate solution from melamine-based exhaust gases according to claim 2, characterized in that, The neutralization reactor (1) is provided with a mixing assembly (14), which comprises a pipe joint (141) and an impeller (142) arranged in the pipe joint (141); the pipe joint (141) is arranged between the tail gas main inlet (12) and the tail gas secondary inlet (15) on the neutralization reactor (1).
4. A device for producing an ammonium nitrate solution from a melamine-based exhaust gas according to claim 3, characterized in that The center of the impeller (142) is provided with a flow discharge hole (1421), and the outer edge is provided with a flow distribution slot (1422) which is spaced apart along the circumference.
5. A device for producing an ammonium nitrate solution from melamine-based exhaust gases according to claim 4, characterized in that The flow distribution slot (1422) is arc-shaped, and the arc directions of all the flow distribution slots (1422) are the same; the inlet directions of the tail gas main inlet (12) and the tail gas secondary inlet (15) are consistent with the tangential directions of the arc-shaped flow distribution slots (1422).
6. A device for producing an ammonium nitrate solution from melamine-based exhaust gas according to claim 5, characterized in that The impeller (142) is provided with a central flow collection area (1423) on one side near the tail gas main inlet (12); the central flow collection area (1423) is an annular area, the inner circle of which is the outer edge of the flow discharge hole (1421), and the outer circle of which is close to one end of the flow distribution slot (1422) near the center of the impeller (142); at the same time, the central flow collection area (1423) is recessed towards the inside of the impeller (142).
7. A device for producing an ammonium nitrate solution from a melamine-based exhaust gas according to claim 1 or 6, characterized in that The neutralization flash tank (2) comprises a cylinder (21) and a lower head (22); the reaction liquid inlet (211) is arranged in the middle of the cylinder (21), and the process steam outlet (212) is arranged on the top of the cylinder (21); the head (22) is communicated with the cylinder (21), and the ammonium nitrate solution outlet (221) is arranged on the bottom of the head (22); a circulating liquid pipeline (23) is further arranged on the cylinder (21), and the two ends of the circulating liquid pipeline (23) are respectively a circulating liquid inlet (231) and a circulating liquid outlet (232); the circulating liquid inlet (231) is arranged outside the cylinder (21) and is communicated with a circulating pump (233); the circulating pump (233) is communicated with the ammonium nitrate solution outlet (221) pipeline; the circulating liquid outlet (232) is arranged inside the cylinder (21) and is lower than the reaction liquid inlet (211) and higher than the ammonium nitrate solution liquid level.
8. A device for producing an ammonium nitrate solution from a melamine-based exhaust gas according to claim 7, characterized in that The head (22) is provided with an anti-vortex baffle, which comprises a flow guide cylinder (2221) and a cross-shaped liquid distribution plate (2222). The flow guide cylinder (2221) is tightly fitted in the head (22), and the axis of the flow guide cylinder (2221) coincides with the axis of the head (22). The cross-shaped liquid distribution plate (2222) has a cross-shaped cross section, and is vertically fixed to the inside upper side of the flow guide cylinder (2221).
9. A device for producing an ammonium nitrate solution from melamine-based exhaust gas according to claim 8, characterized in that A plurality of baffle plates (2223) are also fixed on the cross-shaped liquid distribution plate (2222) at intervals.
10. A device for producing an ammonium nitrate solution from a melamine-based exhaust gas according to claim 1, characterized in that A demister (24) is installed on the top of the neutralization flash tank (2) near the position of the process steam outlet (212).