Melamine production and tail gas treatment system

Abstract

The utility model relates to the technical field of melamine production processes, and particularly discloses a melamine production and tail gas treatment system aiming at the problems of complicated process and high cost of the existing melamine production tail gas treatment mode, which comprises a reaction system and a tail gas treatment system arranged at the tail end of the reaction system, the reaction system comprises a reaction fluidized bed and a crystallizer; the tail gas treatment system comprises a washing tower, a cold air pipeline, a backflow pipeline and a tail gas pipeline are arranged at the discharging end of the washing tower, the cold air pipeline is communicated with the crystallizer, the backflow pipeline is communicated with the feeding end of the reaction fluidized bed, and the tail gas pipeline is communicated with a chemical fertilizer tank. The melamine production tail gas is respectively used for recycling and resource reutilization in the system, so that the direct emission of the tail gas is reduced, the pollution to the environment is reduced, meanwhile, the tail gas treatment process is simplified, the tail gas treatment cost is reduced, and the whole production system can realize continuous coordinated operation.

Description

Technical Field

[0001] This utility model relates to the field of melamine production technology, and more specifically, to a melamine production and exhaust gas treatment system. Background Technology

[0002] In the industrial production of melamine, urea and ammonia are generally used as raw materials. Under the action of a catalyst, a high-temperature reaction is carried out to decompose urea molecules into cyanic acid, which then undergoes a condensation reaction to finally synthesize melamine. The main chemical reaction processes involved are as follows:

[0003] 6(NH2)2CO → C3H6N6 + 6NH3 + 3CO2 (1).

[0004] The melamine produced by the above reaction can be cooled, collected, and purified to obtain the final melamine product.

[0005] In traditional industrial melamine production, the resulting exhaust gases typically require complex and cumbersome treatment before they can be discharged or reused, leading to high treatment costs and environmental pollution risks. Therefore, there is an urgent need for a low-cost, high-efficiency method to treat melamine production exhaust gases, thereby improving production efficiency, reducing costs, minimizing pollution, and increasing resource utilization. Utility Model Content

[0006] The purpose of this invention is to solve the problems of cumbersome and costly processes in existing melamine production tail gas treatment methods. This application provides a melamine production and tail gas treatment system, which can achieve the following technical effects.

[0007] This utility model is achieved through the following technical solution:

[0008] This utility model provides a melamine production and tail gas treatment system, including a reaction system and a tail gas treatment system configured at the tail end of the reaction system. The reaction system includes a fluidized bed and a crystallizer; and the tail gas treatment system includes a scrubbing tower. The discharge end of the scrubbing tower is respectively configured with a cold air pipe, a reflux pipe and a tail gas pipe. The cold air pipe is connected to the crystallizer, the reflux pipe is connected to the feed end of the fluidized bed, and the tail gas pipe is connected to a fertilizer tank.

[0009] Preferably, the reaction system includes the reaction fluidized bed, the cooling and filtration system, the crystallizer, and the product collection system connected in sequence. The product collection system includes a multi-stage collector and a hopper disposed at the discharge end of the collector at the end, and the discharge end of the collector at the end is also connected to the washing tower.

[0010] Preferably, the cooling and filtration system includes a hot gas cooler and a filter connected end to end, the feed end of the hot gas cooler being connected to the discharge end of the reaction fluidized bed, and the discharge end of the filter being connected to the feed end of the crystallizer.

[0011] Preferably, the filter is provided with a slag discharge port at the bottom.

[0012] Preferably, a circulation pump is connected to the bottom of the washing tower, and the discharge end of the circulation pump is connected to the top of the washing tower.

[0013] Preferably, the cold air duct is equipped with a cold air fan, and the outlet end of the cold air fan is connected to the crystallizer.

[0014] Preferably, the reflux pipe is equipped with a compressor, and the discharge end of the compressor is connected to the feed end of the reaction fluidized bed.

[0015] The technical solution of this utility model has the following beneficial effects:

[0016] This utility model discloses a melamine production and tail gas treatment system that allows melamine production tail gas to be used for internal system recycling and resource reuse, reducing direct emissions and environmental pollution. It also simplifies the tail gas treatment process, lowers treatment costs, and enables continuous and coordinated operation of the entire production system. Specifically, the tail gas used for internal system recycling can be used for fluidized bed carrier gas recycling and crystallizer auxiliary cooling circulation. The remaining tail gas, which cannot be used or absorbed within the system, can be sent to a fertilizer tank for treatment. Under high temperature and high pressure conditions, urea can be synthesized, thus effectively improving resource utilization and solving the problem of cumbersome melamine production tail gas treatment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the melamine production and exhaust gas treatment system in Example 1.

[0018] Figure reference numerals: 11-Reaction fluidized bed, 121-Hot gas cooler, 122-Filter, 123-Slag discharge port, 13-Crystallizer, 14-Collector, 15-Hoarder, 21-Scrubber, 22-Cold air pipe, 23-Reflux pipe, 24-Tail gas pipe, 25-Circulating pump, 26-Cold air fan, 27-Compressor, 3-Fertilizer tank. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of instruments, equipment, reagents, or raw materials are not specified, they are all conventional products that can be purchased commercially. The following are specific embodiments in conjunction with the accompanying drawings.

[0020] like Figure 1 As shown, this embodiment provides a melamine production and tail gas treatment system, including a reaction system and a tail gas treatment system configured at the tail end of the reaction system. The reaction system includes a reaction fluidized bed 11, a cooling and filtration system, a crystallizer 13, and a product collection system connected in sequence. The cooling and filtration system includes a hot gas cooler 121 and a filter 122 connected at both ends. The feed end of the hot gas cooler 121 is connected to the discharge end of the reaction fluidized bed 11, and the discharge end of the filter 122 is connected to the feed end of the crystallizer 13. The bottom of the filter 122 is provided with a slag discharge port 123 to collect and discharge high-boiling-point impurities and catalyst particles in the cooled and filtered reaction gas.

[0021] In this embodiment, the exhaust gas treatment system includes a scrubbing tower 21. The discharge end of the scrubbing tower 21 is equipped with a cold air pipe 22, a reflux pipe 23, and an exhaust gas pipe 24. The cold air pipe 22 is connected to the crystallizer 13, the reflux pipe 23 is connected to the feed end of the reaction fluidized bed 11, and the exhaust gas pipe 24 is connected to the fertilizer tank 3. A circulating pump 25 is connected to the bottom of the scrubbing tower 21, and the discharge end of the circulating pump 25 is connected to the top of the scrubbing tower 21. A cold air fan 26 is installed in the cold air pipe 22, and the discharge end of the cold air fan 26 is connected to the crystallizer 13. A compressor 27 is installed in the reflux pipe 23, and the discharge end of the compressor 27 is connected to the feed end of the reaction fluidized bed 11.

[0022] In this embodiment, the product collection system includes a multi-stage collector 14 and a hopper 15 disposed at the discharge end of the collector 14 at the end, and the discharge end of the collector 14 at the end is also connected to the washing tower 21.

[0023] The melamine production and tail gas treatment system of this embodiment has the following specific process: urea, the raw material, is fed into the fluidized bed 11 and heated to a high temperature of about 380-400°C under the action of a catalyst. The reaction produces melamine and other byproducts. The reaction product system is then sent to a cooling and filtration system to remove high-boiling-point impurities and catalyst particles from the reaction gas, such as melamine deammoniation products, melamine, melamine amine, and melamine amine, to improve the purity of the melamine gas and ensure the normal operation of the subsequent system. The cooled and filtered gas is sent to the crystallizer 13, where the temperature is reduced by cold air convection, causing the melamine to sublimate and crystallize into a solid product. The remaining tail gas is then treated by washing and compression.

[0024] In the exhaust gas treatment, the crystallized process gas is washed and cooled to remove impurities and harmful components such as fine melamine crystals. The washed gas is processed through three channels: one part enters the compressor 27 for pressurization and can be used as a fluidized bed carrier gas for circulation; another part is sent to the crystallizer 13 via the cold air pipe 22 and the cold air fan 26 to assist in cooling the crystallizer 13; the remaining exhaust gas that cannot be used or absorbed can be directly sent to the fertilizer tank 3 for absorption, realizing resource reuse. Among them, the first two parts of the gas can be recycled within the process system, while the exhaust gas sent to the fertilizer tank 3 is mainly ammonia and carbon dioxide, which are decomposition products of urea, and the volume ratio of the two is about 1-2:3. It can be used to synthesize urea in the fertilizer tank 3 under high temperature and high pressure, which can improve the resource utilization rate and solve the problem of troublesome exhaust gas treatment in melamine production.

[0025] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A melamine production and tail gas treatment system, characterized in that, It includes a reaction system and a tail gas treatment system disposed at the tail end of the reaction system, the reaction system including a reaction fluidized bed (11) and a crystallizer (13); The exhaust gas treatment system includes a scrubbing tower (21), and the discharge end of the scrubbing tower (21) is respectively equipped with a cold air pipe (22), a reflux pipe (23) and an exhaust gas pipe (24). The cold air pipe (22) is connected to the crystallizer (13), the reflux pipe (23) is connected to the feed end of the reaction fluidized bed (11), and the exhaust gas pipe (24) is connected to the fertilizer tank (3).

2. The melamine production and tail gas treatment system according to claim 1, characterized in that, The reaction system includes the reaction fluidized bed (11), the cooling and filtration system, the crystallizer (13), and the product collection system connected in sequence. The product collection system includes a multi-stage collector (14) and a hopper (15) disposed at the discharge end of the collector (14) at the end. The discharge end of the collector (14) at the end is also connected to the washing tower (21).

3. The melamine production and tail gas treatment system according to claim 2, characterized in that, The cooling and filtration system includes a hot gas cooler (121) and a filter (122) connected end to end. The feed end of the hot gas cooler (121) is connected to the discharge end of the reaction fluidized bed (11), and the discharge end of the filter (122) is connected to the feed end of the crystallizer (13).

4. The melamine production and tail gas treatment system according to claim 3, characterized in that, The filter (122) is provided with a slag discharge port (123) at the bottom.

5. The melamine production and tail gas treatment system according to claim 1, characterized in that, The bottom of the washing tower (21) is connected to a circulation pump (25), and the discharge end of the circulation pump (25) is connected to the top of the washing tower (21).

6. The melamine production and tail gas treatment system according to claim 1, characterized in that, The cold air duct (22) is equipped with a cold air fan (26), and the discharge end of the cold air fan (26) is connected to the crystallizer (13).

7. The melamine production and tail gas treatment system according to claim 1, characterized in that, The reflux pipe (23) is equipped with a compressor (27), and the discharge end of the compressor (27) is connected to the feed end of the reaction fluidized bed (11).

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