Device for improving safety of neutralization system in ammonium nitrate production process

Abstract

The utility model discloses a device for improving the safety of a neutralization system in an ammonium nitrate production process, which solves the problem that an ammonium nitrate device must be stopped when a melamine device breaks down or is overhauled, and comprises a CO2 pipeline, an ammonia gas pipeline, a triamine tail gas pipeline, a nitric acid pipeline and a neutralizer, a carbon dioxide pipeline is arranged on the triamine tail gas pipeline in front of the filter, an inlet of the carbon dioxide pipeline is connected with a CO2 compressor outlet pipeline of the urea device to provide CO2 for simulating the triamine tail gas working condition, and an ammonia gas pipeline is further arranged on the triamine tail gas pipeline. According to the utility model, NH3 is supplemented, a proper amount of CO2 is matched, the working condition of triamine tail gas during normal production is simulated, seamless switching in operation can be realized, and when the triamine device has an abnormal condition or stops, abnormal stop or load reduction of upstream and downstream related devices is avoided, and meanwhile, the safety of the ammonium nitrate device is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of ammonium nitrate production, in particular to a device for improving the safety of a neutralization system in an ammonium nitrate production process. Background Art

[0002] In the field of ammonium nitrate production, traditional production methods mostly use neutralization reactions under high or medium pressure conditions. Due to the large amount of materials in the atmospheric pressure reactor, the slow and uneven reaction speed, and the large amount of exhaust gas leakage, there are certain safety risks. Therefore, the atmospheric pressure neutralization method for ammonium nitrate production (except for the melamine exhaust gas comprehensive utilization project) has been explicitly eliminated by the state; the existing ammonium nitrate plant is a melamine exhaust gas atmospheric pressure co-production process (belonging to the melamine exhaust gas comprehensive utilization project).

[0003] However, in the melamine tail gas atmospheric pressure co-production process, the ammonium nitrate unit and the melamine unit are highly correlated, and the two usually need to be started and stopped at the same time. Once the melamine unit fails or needs to be repaired, the ammonium nitrate unit must also be shut down. This not only affects the normal production of ammonium nitrate, but may also cause a chain reaction to upstream and downstream units, resulting in unplanned shutdowns or abnormal operating conditions of the entire production system. In this case, not only does it increase the workload of operators and reduce the economic benefits of the enterprise, but it also increases the safety risks of chemical plants when starting and stopping. Utility Model Content

[0004] The utility model provides a device for improving the safety of a neutralization system in an ammonium nitrate production process, so as to solve the technical problem that the ammonium nitrate device must be stopped when the melamine device fails or is under maintenance.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present application provides a device for improving the safety of the neutralization system in the ammonium nitrate production process, comprising a triamine tail gas pipeline, a nitric acid pipeline and a neutralizer, wherein a filter is provided on the triamine tail gas pipeline, a carbon dioxide pipeline is provided on the triamine tail gas pipeline in front of the filter, the inlet of the carbon dioxide pipeline is connected to the CO2 compressor outlet pipeline of the urea device, and an ammonia pipeline is also provided on the triamine tail gas pipeline to provide an ammonia source for the production of ammonium nitrate; when the triamine device fails or is under maintenance, CO2 and NH3 are added to the neutralizer through the triamine tail gas pipeline to simulate the working condition of the triamine tail gas.

[0007] Furthermore, a flow control valve is provided on the carbon dioxide pipeline to control the amount of carbon dioxide introduced to ensure that the gas components added to the neutralizer under simulated working conditions are similar to the gas components in the triamine tail gas during normal production.

[0008] Furthermore, the neutralizer is provided with a nitric acid distribution pipe and an ammonia distribution pipe, the triamine tail gas pipeline is connected to the ammonia distribution pipe, the nitric acid pipeline is connected to the nitric acid distribution pipe, and the nitric acid distribution pipe is located above the ammonia distribution pipe.

[0009] Beneficial effects achieved by the utility model:

[0010] The utility model provides a device for improving the safety of the neutralization system in the ammonium nitrate production process. When a melamine device fails or stops, CO2 and NH3 are added to the neutralizer through a triamine tail gas pipeline to simulate the working conditions of the triamine tail gas during normal production. Due to the presence of gaseous carbon dioxide, the carbon dioxide is evenly distributed in the neutralizer through gas agitation, and no hot spots or dead corners appear in the neutralizer. The neutralizing liquid is a gas-liquid mixture, and the material does not increase compared with the normal production of the melamine tail gas atmospheric pressure method co-production process. The neutralization temperature and the concentration of the neutralizing liquid remain unchanged. By utilizing the existing supplementary ammonia and matching it with appropriate carbon dioxide, seamless switching can be achieved in operation, and abnormal shutdown of related upstream and downstream devices is avoided, so that when an abnormal situation occurs in the ammonium nitrate device of the melamine tail gas atmospheric pressure method co-production process, the safety of the ammonium nitrate device is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of an embodiment of the utility model;

[0012] Reference numerals:

[0013] 1. Triamine tail gas pipeline; 2. Nitric acid pipeline; 3. Neutralizer; 4. Filter; 5. Carbon dioxide pipeline; 6. Ammonia pipeline; 7. Nitric acid distribution pipe; 8. Ammonia distribution pipe; 9. Flow control valve.

[0014] The drawings are only used for illustrative purposes and should not be construed as limitations on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The same or similar numbers correspond to the same or similar parts. The terms describing the positional relationship in the drawings are only used for illustrative purposes and should not be construed as limitations on this patent. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0016] The technical solution of the present utility model is described in detail below in conjunction with the specific drawings.

[0017] A device for improving the safety of the neutralization system in the ammonium nitrate production process comprises a triamine tail gas pipeline 1, a nitric acid pipeline 2 and a neutralizer 3, wherein the triamine tail gas pipeline 1 is provided with a filter 4, the triamine tail gas pipeline 1 before the filter 4 is provided with a carbon dioxide pipeline 5, the inlet of the carbon dioxide pipeline 5 is connected to the CO2 compressor outlet pipeline of the urea device, and the carbon dioxide pipeline 5 is provided with a flow control valve 9 to control the amount of carbon dioxide introduced to ensure that the gas components added to the neutralizer under the simulated working condition are the same as the gas components in the triamine tail gas during normal production. The triamine tail gas pipeline 1 is also provided with an ammonia pipeline 6 to provide a supplementary ammonia source for ammonium nitrate production; when the triamine device fails or is overhauled, CO2 and NH3 are added to the neutralizer 3 through the carbon dioxide pipeline 5 and the ammonia pipeline 6 to simulate the working conditions of the triamine tail gas during normal production. The neutralizer of this device is an improved internal circulation neutralization reactor, which is composed of two sections, the upper section is a separation section, and the lower section is a reaction section. The lower section is composed of an inner tube and an outer tube. The neutralization reaction occurs in the inner tube. Nitric acid and triamine tail gas are sprayed from the nozzle, contact each other, react violently and release a large amount of heat, so that the solution temperature rises sharply and part of the water evaporates. The solution is a gas-liquid mixture with a lighter specific gravity and rises to the upper section of the neutralizer; the gas-liquid mixture obtained by the reaction is separated in the upper section of the neutralizer, and the process steam is washed in the scrubber. Except for part of the acidic ammonium nitrate liquid of about 76%-78% flowing out through the outlet of the neutralizer, most of the solution circulates along the outer tube to the lower section and enters the neutralization inner tube; in addition, the triamine tail gas contains gaseous carbon dioxide. Through the stirring of the gas, the contact area of ​​ammonia and nitric acid is large, which can ensure a fast and uniform reaction speed, and the reactor tail gas does not leak, ensuring that there are no hot spots or dead corners in the neutralizer; the operation flexibility is large, and it can be operated at 40%-110%; and due to the presence of carbon dioxide, the neutralizer is a gas-liquid mixture, and the amount of ammonium nitrate online material is small. At the same time, in order to reduce the storage of ammonium nitrate liquid in the reactor, during the start-up and shutdown period, a certain amount of nitrogen (inert gas) is added to the melamine tail gas distributor at the bottom of the ammonium nitrate neutralizer to replace the carbon dioxide in the melamine tail gas to stir the neutralizer solution.

[0018] In the melamine tail gas atmospheric pressure co-production process (melamine tail gas comprehensive utilization project), the ammonium nitrate unit is mostly in the key intermediate link of the circular economy industrial chain, while the triamine unit is shut down for maintenance 2-3 times a year, which takes about 12-16 days. If the ammonium nitrate unit and the triamine unit are started and shut down at the same time, the shutdown of the triamine unit will lead to the shutdown of the ammonium nitrate unit, the shutdown of the upstream nitric acid unit, the reduction of production of the synthetic ammonia unit, and the shutdown of the downstream compound fertilizer unit. Such large-scale unplanned shutdown or abnormal operation of the units not only increases the workload of the operators and reduces the social and economic benefits of the enterprise, but also increases the safety risks of starting and shutting down certain chemical units (generally, most operational safety accidents occur under abnormal conditions, especially during the start-up and shutdown of the units).

[0019] Accordingly, in order to avoid abnormal shutdown of upstream and downstream devices due to failure or maintenance of the triamine device and to improve the intrinsic safety of the melamine tail gas atmospheric pressure method co-production of ammonium nitrate device, a CO2 supply system is added, and a carbon dioxide pipeline 5 is provided on the triamine tail gas pipeline 1 in front of the filter 4. The inlet of the carbon dioxide pipeline 5 is connected to the CO2 compressor outlet pipeline of the urea device. When the triamine device is shut down, hot CO2 gas is added to the neutralizer 3 through the carbon dioxide pipeline 5, and NH3 is added through the original supplementary ammonia pipeline (6) to simulate the working condition of the triamine tail gas.

[0020] The CO2 required for simulating triamine tail gas is directly provided by the urea unit without external purchase, and its temperature is about 130°C, which is close to the temperature of triamine tail gas. The CO2 addition point is set in front of the existing triamine tail gas filter to ensure that no impurities are brought into the ammonium nitrate neutralizer.

[0021] Regularly analyze the content of NH3 and CO2 under simulated working conditions to ensure that it is similar to the content in the triamine tail gas under normal working conditions. At the same time, determine the amount of CO2 added according to the operating load range of the ammonium nitrate neutralizer to avoid crystallization problems caused by too little CO2 addition.

[0022] Due to the presence of gaseous CO2, the material distribution in the neutralizer is more uniform through gas agitation, avoiding the occurrence of hot spots and dead corners. The neutralizing liquid is a gas-liquid mixture. Compared with the melamine tail gas atmospheric pressure co-production process, the material volume has not increased, and the neutralization temperature and neutralization liquid concentration remain unchanged. By using the existing supplementary ammonia and CO2 in an appropriate ratio, seamless switching operation is achieved, avoiding abnormal shutdown of upstream and downstream related devices, thereby improving the safety of the ammonium nitrate device.

[0023] The serial numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments. The above are only preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A device for improving the safety of a neutralization system in an ammonium nitrate production process, characterized in that: The invention comprises a triamine tail gas pipeline (1), a nitric acid pipeline (2) and a neutralizer (3), wherein the triamine tail gas pipeline (1) is provided with a filter (4), the triamine tail gas pipeline (1) before the filter (4) is provided with a carbon dioxide pipeline (5), the inlet of the carbon dioxide pipeline (5) is connected to the outlet pipeline of the CO2 compressor of the urea device, and the triamine tail gas pipeline (1) is also provided with an ammonia pipeline (6) to provide a supplementary ammonia source for ammonium nitrate production; when the triamine device fails or is under maintenance, CO2 and NH3 are added to the neutralizer (3) through the carbon dioxide pipeline (5) and the ammonia pipeline (6) to simulate the working condition of the triamine tail gas.

2. A device for improving the safety of a neutralization system in an ammonium nitrate production process according to claim 1, characterized in that: The carbon dioxide pipeline (5) is provided with a flow control valve (9) to control the amount of carbon dioxide introduced, thereby ensuring that the gas components added to the neutralizer under simulated working conditions are similar to the gas components in the triamine tail gas during normal production.

3. A device for improving the safety of a neutralization system in an ammonium nitrate production process according to claim 1, characterized in that: The neutralizer (3) is provided with a nitric acid distribution pipe (7) and an ammonia distribution pipe (8), the triamine tail gas pipeline (1) is connected to the ammonia distribution pipe (8), the nitric acid pipeline (2) is connected to the nitric acid distribution pipe (7), and the nitric acid distribution pipe (7) is located above the ammonia distribution pipe (8).

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