Treatment method and system for preventing ammonium sulfate blockage in caprolactam production
By adding benzene and amide oil to the production of caprolactam, the problem of ammonium sulfate blockage is solved by using its mutual solubility and insolubleness with water, and the amount of benzene extraction and equipment size are reduced, energy consumption is reduced, and operation is achieved. Economic benefits.
Patent Information
- Application Number
- CN202410847779.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2024-12-31
AI Technical Summary
In the existing caprolactam production process, ammonium sulfate can easily cause pipeline blockage and deposition after cooling, resulting in inconvenience in operation. When adding water to solve the blockage problem, the amount of benzene extraction and equipment size are increased, and energy consumption is increased.
After the caprolactam crystallization, benzene is added to mix with amide oil. By controlling the amount and proportion of benzene, benzene and water are used to dissolve ammonium sulfate and prevent ammonium sulfate from precipitating out and blocking the pipeline, while reducing the amount of benzene extraction and equipment size.
It effectively solves the problem of ammonium sulfate blockage, reduces the amount of benzene extraction and equipment size, reduces the energy consumption of debenzene, and has economic advantages.
Smart Images
Figure CN119215465A_ABST
Abstract
Description
Technical Field
[0001] This patent relates to a caprolactam production process, and more particularly to a method and treatment system for ammonium sulfate blockage in caprolactam production. Background Art
[0002] Caprolactam is an important raw material for chemical fiber and engineering plastics. At present, the main production process for caprolactam is the cyclohexanone-hydroxylamine route based on the Beckmann rearrangement of cyclohexanone oxime, that is, benzene is hydrogenated to produce cyclohexane, cyclohexane is oxidized to produce cyclohexanone, and then hydroxylamine is oximated to produce cyclohexanone oxime, and then caprolactam is obtained by Beckmann rearrangement. After the Beckmann rearrangement reaction, ammonia is added to neutralize the fuming sulfuric acid in the rearrangement liquid. In the crystallizer, water is evaporated by the heat of the neutralization reaction. The neutralization product ammonium sulfate forms a slurry in the crystallizer. The caprolactam solution and the ammonium sulfate slurry are separated. The amide oil (caprolactam aqueous solution is called amide oil) containing a large amount of ammonium sulfate solution is extracted at the interface of the crystallizer by the P2 pump. After the conventional method of solving the blockage: the phase separation of the decomposition device (phase separator) is followed by the amide oil storage tank buffer for static separation, and the extraction tower is pumped by the P4 pump. After benzene extraction, it enters the subsequent process. The ammonium sulfate mother liquor at the bottom of the amide oil storage tank is returned to the inlet of the crystallizer circulation pump P1 through the P3 pump. Generally, the crystallizer evaporation temperature is 56-58℃, the caprolactam concentration in the amide oil is 75%-76%, and the extracted amide oil contains saturated ammonium sulfate solution. When the temperature drops, ammonium sulfate will precipitate and block the pipeline. Ammonium sulfate will also deposit at the bottom of the amide oil storage tank. These problems need to be cleaned regularly by operators, which brings great inconvenience to the operation. At present, the solution to the problem of ammonium sulfate precipitation blocking the pipeline and deposition is mainly to add water to the pipeline between the P2 pump and the crystallizer (see Figure 1 ), dissolving ammonium sulfate avoids pipeline blockage, and also reduces the caprolactam concentration of the extracted amide oil to 72.5%. Although adding water has solved the problem of ammonium sulfate blocking the pipeline when amide oil is extracted, since the subsequent amide oil needs to be extracted by benzene extraction tower, adding water increases the amount of benzene added during benzene extraction. Basically, 0.034 tons of water are needed for 1 ton of amide oil, and 0.37 tons of benzene are needed for benzene extraction, which increases the size of the benzene extraction tower equipment, increases the energy consumption of debenzening in the later stage, and increases the amount of wastewater. Summary of the invention
[0003] The invention provides a method and system for preventing ammonium sulfate from clogging in caprolactam production, which solves the problem of pipeline clogging when amide oil is extracted and reduces the amount of benzene added and the size of equipment for benzene extraction.
[0004] The technical solution to the above problem is a treatment method for preventing ammonium sulfate from clogging in caprolactam production. After crystallization, caprolactam is transported to an amide oil storage tank for separation. The method includes adding benzene before caprolactam enters the amide oil storage tank after crystallization.
[0005] Preferably, the mass ratio of the added benzene to the amide oil is 1:0.5-100, and the amount of benzene added in the subsequent benzene extraction is reduced by at least 1:10.
[0006] A processing system for preventing ammonium sulfate from clogging in caprolactam production. The caprolactam production system includes a conventional method for solving the clogging: a separator, an amide oil storage tank, and a benzene extraction tower. The crystallizer is connected to the upper part of the amide oil storage tank through a second delivery pump, the amide oil storage tank is connected to the benzene extraction tower through a fourth delivery pump, and the lower part of the amide oil storage tank is connected to the separator through a third delivery pump. The processing system includes a first benzene injection pipe between the separator and the second delivery pump and / or a second benzene injection pipe between the second delivery pump and the amide oil storage tank, benzene enters the second delivery pump through the first benzene injection pipe and / or benzene enters the amide oil storage tank through the second injection pipe.
[0007] Preferably, a first control valve is provided on the first benzene injection pipe.
[0008] Preferably, the second benzene injection pipe is inserted into the second control valve.
[0009] Preferably, the processing system further comprises a controller, the first control valve is an electrically controlled valve, and the controller is electrically connected to the first control valve.
[0010] Preferably, the processing system further comprises a controller, the second control valve is an electrically controlled valve, and the controller is electrically connected to the second control valve.
[0011] The advantages of the present invention are: 1) benzene is miscible with caprolactam and water, and after adding benzene, the water in the amide oil dissolves the ammonium sulfate, thus solving the problem of pipeline blockage when the amide oil is extracted.
[0012] 2) After adopting this scheme, at least 0.1 tons of benzene is added to the benzene extraction tower during extraction, the size of the benzene extraction tower equipment is reduced by 2-5%, the equipment investment is reduced, and the energy consumption for debenzening in the later stage is reduced by more than 1% accordingly, which has great economic advantages for industrialized amine ammonia projects. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 This is a prior art diagram.
[0014] Figure 2 This is a schematic diagram of the structure of this patent.
[0015] Figure 3 This is a schematic diagram of the preferred structure of this patent.
[0016] As shown in the figure: separator 1, amide oil storage tank 2, benzene extraction tower 3, second delivery pump 4, fourth delivery pump 5, third delivery pump 6, first benzene injection pipe 7, second benzene injection pipe 8, first control valve 9, second control valve 10, controller 11. DETAILED DESCRIPTION
[0017] A treatment method for preventing ammonium sulfate from clogging in caprolactam production. Caprolactam is transported to an amide oil storage tank for separation after passing through a separator. The method comprises adding benzene after the caprolactam separator and before entering the amide oil storage tank. The mass ratio of the added benzene to the mass of the amide oil is 1:0.5-100.
[0018] like Figure 2 As shown, a treatment system for preventing ammonium sulfate from being blocked in caprolactam production, the caprolactam production system includes a separator 1, an amide oil storage tank 2, and a benzene extraction tower 3, the separator 1 is connected to the upper part of the amide oil storage tank 2 through a second delivery pump 4, the amide oil storage tank 2 is connected to the benzene extraction tower 3 through a fourth delivery pump 5, and the lower part of the amide oil storage tank 2 is connected to the separator 1 through a third delivery pump 6, the treatment system includes a first benzene injection pipe 7 between the separator 1 and the second delivery pump 4 and / or a second benzene injection pipe 8 between the second delivery pump 4 and the amide oil storage tank 2, benzene enters the second delivery pump 4 through the first benzene injection pipe 7 and / or benzene enters the amide oil storage tank 2 through the second injection pipe 8.
[0019] Working principle: Taking advantage of the physical properties that benzene and water are immiscible, benzene and water are miscible with caprolactam, benzene does not tolerate ammonium sulfate, and caprolactam does not dissolve ammonium sulfate, the amount of water dissolved in caprolactam is reduced by adding benzene, so that the ammonium sulfate in the water phase changes from a saturated state to an unsaturated state, thereby preventing the precipitation of ammonium sulfate and clogging the pipeline.
[0020] The amide oil (caprolactam aqueous solution is called amide oil) extracted from the decanter by the second delivery pump 4 is buffered in the amide oil storage tank 2 for static separation, and is pumped into the extraction tower 3 by the fourth delivery pump 5. After adding benzene at the output port of the decanter, it enters the amide oil storage tank 2 and the ammonium sulfate mother liquor at the bottom is returned to the decanter 1 through the third delivery pump 6; benzene enters the second delivery pump 4 through the first benzene injection pipe 7 and finally enters the amide oil storage tank 2, and / or the second benzene injection pipe 8 enters the amide oil storage tank 2. The mass ratio of amide oil to benzene added is 0.01-1 ton. The amide oil after adding benzene enters the amide oil storage tank 2. After being buffered in the amide oil storage tank 2, the amide oil is pumped into the benzene extraction tower 3 through the fourth delivery pump 5. The mother liquor containing sodium sulfate enters the decanter (phase separator) 1 through the third delivery pump 6, and can also be sent to the ammonium sulfate crystallizer. There is no ammonium sulfate blockage in the entire pipeline.
[0021] Preferred as Figure 3As shown, the first benzene injection pipe 7 is provided with a first control valve 9.
[0022] Preferably, the second benzene injection pipe 8 is inserted into the second control valve 10 , the treatment system further comprises a controller 11 , the first control valve 9 is an electrically controlled valve, and the controller 11 is electrically connected to the first control valve 9 .
[0023] Preferably, the processing system further includes a controller 11 , the second control valve 10 is an electrically controlled valve, and the controller 11 is electrically connected to the second control valve 10 .
[0024] During operation, the controller 11 controls the opening of the first control valve 9 and the second control valve 10 according to the set parameters, thereby controlling the benzene injection amount. The set parameters of the controller 11 are related to the working power of the third delivery pump 3.
Claims
1. A method for preventing ammonium sulfate from clogging in caprolactam production, wherein the caprolactam is separated by phase separation in a separator and then transported to an amide oil storage tank for separation, wherein: The method comprises adding benzene after the caprolactam separator and before entering the amide oil storage tank.
2. A method for preventing ammonium sulfate from clogging in caprolactam production according to claim 1, characterized in that: The mass ratio of the added mass of benzene to the mass of the amide oil is 1:0.5-100.
3. A treatment system for preventing ammonium sulfate from clogging in caprolactam production, the caprolactam production system comprising a separator and an amide oil storage tank, the separator is connected to the upper part of the amide oil storage tank through a second delivery pump, the lower part of the amide oil storage tank is connected to the benzol extraction tower through a fourth delivery pump, and the lower part of the amide oil storage tank is connected to the separator through a third delivery pump, characterized in that: The processing system includes a first benzene injection pipe between the filter and the second delivery pump and / or a second benzene injection pipe between the second delivery pump and the amide oil storage tank, and benzene enters the second delivery pump through the first benzene injection pipe and / or benzene enters the amide oil storage tank through the second injection pipe.
4. A treatment system for preventing ammonium sulfate from clogging in caprolactam production according to claim 3, characterized in that: The first benzene injection pipe is provided with a first control valve.
5. A treatment system for preventing ammonium sulfate from clogging in caprolactam production according to claim 3, characterized in that: The second benzene injection pipe is inserted into the second control valve.
6. A treatment system for preventing ammonium sulfate from clogging in caprolactam production according to claim 4, characterized in that: The processing system further includes a controller, the first control valve is an electrically controlled valve, and the controller is electrically connected to the first control valve.
7. A treatment system for preventing ammonium sulfate from clogging in caprolactam production according to claim 5, characterized in that: The processing system further comprises a controller, wherein the second control valve The door is an electrically controlled valve, and the controller is electrically connected to the second control valve.