Pretreatment device for caprolactam refining raffinate

Abstract

The utility model provides a pretreatment device for caprolactam refining raffinate, which is characterized in that a raffinate tank is communicated with the middle part of a solvent recovery tower through a raffinate tank discharge pump by a pipeline, the top of the solvent recovery tower is communicated with a solvent recovery tower top condenser and a solvent recovery tower reflux tank through pipelines, and the solvent recovery tower reflux pump is circularly communicated with the upper part of the solvent recovery tower; the bottom of the solvent recovery tower is communicated with the middle of the concentration tower through a solvent recovery tower kettle pump by a pipeline; the top of the concentration tower is circularly communicated with a concentration tower top condenser, a concentration tower reflux tank, a concentration tower reflux pump and the upper part of the concentration tower through pipelines; the bottom of the concentration tower is communicated with the upper part of the benzene extraction tower through a concentration tower kettle pump through a pipeline. The caprolactam refining raffinate recycling device solves the problem of high energy consumption caused by the fact that a large amount of caprolactam refining raffinate returns to an ammonium sulfate crystallization process, greatly reduces the circulation volume of the caprolactam refining raffinate, and greatly reduces accumulation of impurities in the device as the impurities and sewage are discharged to the sewage treatment device.

Description

TECHNICAL FIELD

[0001] The utility model relates to caprolactam production technical field relates to a kind of caprolactam refining residual liquid's pretreatment device. BACKGROUND

[0002] Caprolactam (CPL) is an important organic chemical raw material, mainly used for producing polyamide 6 engineering plastics and polyamide 6 fiber. Caprolactam refining generally through neutralization, extraction (including solvent distillation), back extraction, ion exchange, hydrogenation, evaporation concentration, pre-distillation, distillation and other processes to refine finished caprolactam. In the caprolactam refining process, most of the inorganic impurities and water-soluble organic impurities are discharged with the raffinate phase (aqueous phase residual liquid), and then most of the oil-soluble organic impurities are carried out with the raffinate phase (organic solvent phase) in the back extraction process. The subsequent ion exchange unit further removes inorganic impurities and adsorbs a small amount of organic impurities, and the remaining impurities are further removed in the evaporation concentration, pre-distillation and distillation units. The impurities with lower boiling point and azeotropic with water are returned to the previous ammonium sulfate neutralization crystallization process with a small amount of caprolactam in the multi-effect evaporation condensate water, flash condensate water and pre-distillation condensate water to reduce the loss of caprolactam. The impurities with higher boiling point are left in the residual liquid of multi-stage distillation and are also returned to the previous ammonium sulfate neutralization crystallization process to recover caprolactam therein. Although the above-mentioned traditional refining process can obtain high-purity caprolactam product, it has the problems of large residual liquid circulation amount, high energy consumption and impurities accumulation in the system affecting product quality. For example, a 200,000 tons / year caprolactam device, the residual liquid circulation amount reaches 10 tons / hour, the residual liquid contains about 25% organic solvent, 20% caprolactam, 55% water and numerous impurities. Under the current situation of advocating "high efficiency, high quality, low consumption and environmental protection", it is urgent to make appropriate improvements and upgrades to reduce the energy consumption of caprolactam production device. Patent CN209997226U discloses a kind of caprolactam residual liquid recovery device, which comprises: residual liquid input pipeline, residual liquid buffer tank, vacuum pump, residual liquid output pipeline and residual liquid conveying pipeline. The residual liquid buffer tank is provided, and the residual liquid buffer tank is pumped into vacuum by vacuum pump, the flowability of residual liquid in pipeline is enhanced, the amount of residual liquid is reduced and the instantaneous yield is improved, and the efficiency of distillation system is improved, the circulation amount of residual liquid in the system is reduced. The patent technology does not completely remove the impurities in the residual liquid. Patent CN222064295U discloses a kind of caprolactam refining residual liquid's processing device, through a series of processes such as alkali washing, desolventizing, benzene washing, water washing and distillation, caprolactam product is recovered from caprolactam residual liquid. The patent technology is suitable for large-scale caprolactam production device. SUMMARY

[0003] In view of the above technical problems, the utility model provides a kind of caprolactam refining residual liquid's pretreatment device.

[0004] The utility model discloses a technical scheme as follows:

[0005] A kind of pre-treatment device of caprolactam refining residual liquid, the device includes residual liquid tank, residual liquid tank is communicated with middle part of solvent recovery column by pipeline through residual liquid tank discharge pump, solvent recovery column and solvent recovery column reboiler circulation communication, solvent recovery column top is communicated with solvent recovery column top condenser, solvent recovery column reflux tank, solvent recovery column reflux pump and solvent recovery column upper portion circulation by pipeline, solvent recovery column bottom is communicated with middle part of concentration column by pipeline through solvent recovery column kettle pump, concentration column and concentration column reboiler circulation communication, concentration column top is communicated with concentration column top condenser, concentration column reflux tank, concentration column reflux pump and concentration column upper portion circulation by pipeline, concentration column bottom is communicated with benzene extraction column upper portion by pipeline through concentration column kettle pump, benzene extraction column and benzene extraction column reboiler circulation communication, benzene extraction column kettle is also provided with extractant access pipe, benzene extraction column top is communicated with benzene extraction column circulation by pipeline through extraction column top condenser, benzene extraction column reflux tank, benzene extraction column reflux pump and benzene extraction column.

[0006] Preferably, the solvent recovery column reboiler, concentration column reboiler, benzene extraction column reboiler are respectively communicated with factory steam pipeline. The residual liquid generated in the caprolactam refining production process is collected by pipeline and then introduced into the residual liquid tank. The residual liquid is transported to the middle part of the solvent recovery column by the residual liquid tank discharge pump. The organic solvent entrained part of light component impurities is collected from the top of the column and sent to the solvent treatment process for further treatment and recovery of the solvent. The column kettle collected residual liquid is transported to the middle part of the concentration column by the solvent recovery column kettle pump. The water entrained part of light component impurities is collected from the top of the column and sent to the sewage treatment process for further treatment. The column kettle concentrated residual liquid is transported to the upper part of the benzene extraction column by the concentration column kettle pump. The extractant preferably uses benzene which has good extraction effect. Benzene is introduced from the column kettle, and the residual liquid flows from the top of the benzene washing column downward. Benzene flows from the bottom of the column upward. The residual liquid and benzene are countercurrently contacted in the benzene washing column. Benzene extracts caprolactam from the residual liquid and is collected from the top of the column. The heavy fraction impurities collected from the benzene extraction column kettle are transported to the sewage treatment section for further treatment by the benzene extraction column kettle pump.

[0007] Preferably, the solvent recovery column reflux pump is also communicated with the solvent treatment device by pipeline, the concentration column reflux pump is also communicated with the sewage treatment device by pipeline, the benzene extraction column reflux pump is also communicated with the ammonium sulfate crystallization device by pipeline, and the benzene extraction column bottom is communicated with the sewage treatment device by the benzene extraction column kettle pump.

[0008] Preferably, the residual liquid tank, solvent recovery column reflux tank, concentration column reflux tank and benzene extraction column reflux tank are communicated with the tail gas treatment device by pipeline.

[0009] Preferably, the solvent recovery column and concentration column use atmospheric column, the tray packing is wire mesh packing, 4-7 layers of packing are provided, liquid sprays are provided in the reflux layer and the feed layer, liquid distributors are provided above each layer of packing, and a mist eliminator is provided at the top of the column.

[0010] Preferably, the benzene extraction column is a rotating disc column with 5-8 trays.

[0011] The caprolactam refining residual liquid pretreatment device of the utility model, through solvent recovery, concentration, extraction and other processes in turn to the caprolactam refining residual liquid pretreatment, the organic solvent in the residual liquid is recovered, and the caprolactam crude product is extracted and returned to the ammonium sulfate neutralization crystallization process and mixed with amide oil, and then refined and purified through the caprolactam refining system, and the sewage containing a large amount of impurities and heavy component impurities are discharged to the sewage treatment device.

[0012] The utility model has the advantages that:

[0013] The caprolactam refining residual liquid pretreatment device of the utility model, through solvent recovery, concentration, extraction and other processes in turn to the caprolactam refining residual liquid pretreatment, the organic solvent in the residual liquid is recovered, and the caprolactam crude product is extracted and returned to the ammonium sulfate neutralization crystallization process and mixed with amide oil, and then refined and purified through the caprolactam refining system, and the sewage containing a large amount of impurities and heavy component impurities are discharged to the sewage treatment device. BRIEF DESCRIPTION OF DRAWINGS

[0014] The utility model will be further described below in combination with the drawings.

[0015] Figure 1 The utility model is specific implementation process diagram.

[0016] Figure 2 The utility model is schematic diagram.

[0017] In the drawing, residual liquid tank 1, residual liquid tank discharge pump 2, solvent recovery tower 3, solvent recovery tower top condenser 4, solvent recovery tower backflow tank 5, solvent recovery tower backflow pump 6, solvent recovery tower reboiler 7, solvent recovery tower kettle discharge pump 8, concentration tower 9, concentration tower condenser 10, concentration tower backflow tank 11, concentration tower backflow pump 12, concentration tower reboiler 13, concentration tower kettle discharge pump 14, benzene extraction column 15, benzene extraction column condenser 16, benzene extraction column backflow tank 17, benzene extraction column backflow pump 18, benzene extraction column reboiler 19, benzene extraction column kettle discharge pump 20, solvent treatment device 21, sewage treatment device 22, ammonium sulfate crystallization device 23, tail gas treatment device 24. DETAILED DESCRIPTION

[0018] The technical scheme of the utility model is further described below in combination with the drawings and examples, but the protection scope of the utility model is not limited to this. The specific embodiment described herein is only used for illustrating and explaining the present disclosure, and is not used for limiting the present disclosure. The equivalent replacement or corresponding improvement made to the content of the utility model still belongs to the protection scope of the utility model.

[0019] Example 1

[0020] As Figure 1 shown. A kind of caprolactam refining residual liquid pre-treatment device, residual liquid generated in caprolactam refining production process is gathered after being passed through pipeline and is passed into residual liquid tank 1, residual liquid is transported to the middle part of solvent recovery column 3 by residual liquid tank discharge pump 2, 0.5MPa factory steam is passed through pipeline and is passed into solvent recovery column reboiler 7 as the heat source of solvent recovery column 3, mass transfer and heat transfer occur in the mixture material on packing in solvent recovery column 3, light component solvent entrains part of impurities and flows from bottom to top, after cooling by solvent recovery column top condenser 4, it flows into solvent recovery column reflux tank 5 by itself, part of solvent returns to solvent recovery column 3 by solvent recovery column reflux pump 6 to control tower top temperature, part of solvent containing impurities is extracted from the top and is sent to solvent treatment process 21 for further treatment and recycling, residual liquid after desolventizing is extracted from the bottom of column and is transported to the middle part of concentration column 9 by solvent recovery column bottom pump 8;0.5MPa factory steam is passed through pipeline and is passed into concentration column reboiler 13 as the heat source of concentration column 9, mass transfer and heat transfer occur in the mixture material on packing in concentration column 9, water entrains part of light component impurities and flows from bottom to top, after cooling by concentration column top condenser 10, it flows into concentration column reflux tank 11 by itself, part of solvent returns to concentration column 9 by concentration column reflux pump 12 to control tower top temperature, part of sewage containing impurities is extracted from the top and is sent to sewage treatment process 22 for treatment, concentrated residual liquid is extracted from the bottom of column and is transported to the upper part of benzene extraction column 15 by concentration column bottom pump 14;0.5MPa factory steam is passed through pipeline and is passed into benzene extraction column reboiler 19 as the heat source of benzene extraction column 15, extractant benzene is passed through pipeline and is passed into the bottom of benzene extraction column 15, mass transfer and heat transfer occur in the mixture material on packing in benzene extraction column 15, extractant benzene extracts caprolactam in residual liquid and flows from bottom to top, after cooling by extraction column top condenser 16, it flows into benzene extraction column reflux tank 17 by itself, part of benzene caprolactam solution returns to the upper part of benzene extraction column 15 by benzene extraction column reflux pump 18 to control tower top temperature, part of benzene caprolactam solution is extracted from the top and is recycled to sulfur ammonium crystallization process 23, is mixed with amide oil and then is sent to caprolactam refining process for further refining to obtain caprolactam product, heavy component impurities are extracted from the bottom of column and are transported to sewage treatment process by benzene extraction column bottom pump 20 for treatment;

[0021] Preferably, residual liquid generated in caprolactam refining production process is gathered after being passed through pipeline and is collected into residual liquid tank 1.

[0022] Preferably, the solvent recovery tower 1 adopts a normal pressure packed tower, the tank is provided with a solvent recovery tower reboiler 7, 0.5 MPa steam produced in the factory is used as a heat source, the temperature of the tank and the top of the tower is determined according to the boiling point of the organic solvent used in the caprolactam refining system, the tray packing is preferably silk screen packing with good mass transfer and heat transfer effect, 4-7 layers of packing are arranged according to the residual liquid amount, liquid sprayers are arranged in the reflux layer and the feed layer, which can uniformly spray liquid onto the liquid distributor, liquid distributors are arranged above each layer of packing, so that the liquid can be uniformly distributed onto the packing, and a mist eliminator is arranged at the top of the tower to trap the liquid entrained in the rising gas phase.

[0023] Preferably, the concentration tower 9 adopts a normal pressure tower, the tank is provided with a concentration tower reboiler 13, 0.5 MPa steam produced in the factory is used as a heat source to control the temperature of the tank at 140 DEG C, the temperature of the top of the tower is controlled at 105 DEG C through reflux, the tray packing is preferably silk screen packing with good mass transfer and heat transfer effect, 4-7 layers of packing are arranged according to the residual liquid amount, liquid sprayers are arranged in the reflux layer and the feed layer, which can uniformly spray liquid onto the liquid distributor, liquid distributors are arranged above each layer of packing, so that the liquid can be uniformly distributed onto the packing, and a mist eliminator is arranged at the top of the tower to trap the liquid entrained in the rising gas phase.

[0024] Preferably, the benzene extraction tower 15 adopts a normal pressure tower, the tank is provided with a benzene extraction tower reboiler 10, 0.5 MPa steam produced in the factory is used as a heat source to control the temperature of the tank at 100 DEG C, the temperature of the top of the tower is controlled at 70 DEG C through reflux, the benzene extraction tower 15 is arranged as a special structure "rotary disc tower", the rotation of the rotating disc on the vertical shaft is driven by the motor arranged at the top of the tower, 5-8 layers of trays are arranged, so that the residual liquid and benzene are uniformly dispersed and fully contacted on the trays to improve the extraction efficiency. The mass flow ratio of the extractant benzene and the residual liquid entering the benzene extraction tower is 3:1.

[0025] Preferably, the residual liquid tank 1, the solvent recovery reflux tank 5, the concentration reflux tank 11 and the benzene extraction reflux tank 17 are all provided with tail gas discharge pipelines, the discharged tail gas is collected through a tail gas collecting pipe and then discharged to a tail gas treatment device 24 for unified treatment.

[0026] The above-mentioned embodiments are only preferred technical solutions of the present application, and should not be regarded as limiting the present application. The embodiments in the present application and the features in the embodiments can be combined with each other as long as there is no conflict. The protection scope of the present application should be based on the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features recorded in the claims. That is, equivalent replacement improvements within this range are also within the protection scope of the present application.

Claims

1. A pre-treatment device for caprolactam refining raffinate, said device comprising a raffinate tank (1), characterized in that, The raffinate tank (1) is communicated with the middle part of the solvent recovery column (3) through a pipeline via a raffinate tank discharge pump (2), the solvent recovery column (3) is circularly communicated with a solvent recovery column reboiler (7), the top of the solvent recovery column (3) is circularly communicated with a solvent recovery column top condenser (4), a solvent recovery column reflux tank (5), a solvent recovery column reflux pump (6) and the upper part of the solvent recovery column (3) through a pipeline, the bottom of the solvent recovery column (3) is communicated with the middle part of a concentration column (9) through a solvent recovery column kettle pump (8); the concentration column (9) is circularly communicated with a concentration column reboiler (13), the top of the concentration column (9) is circularly communicated with a concentration column top condenser (10), a concentration column reflux tank (11), a concentration column reflux pump (12) and the upper part of the concentration column (9) through a pipeline, the bottom of the concentration column (9) is communicated with the upper part of a benzene extraction column (15) through a concentration column kettle pump (14); the benzene extraction column (15) is circularly communicated with a benzene extraction column reboiler (19), and the column kettle of the benzene extraction column (15) is further provided with an extractant access pipe, the top of the benzene extraction column (15) is circularly communicated with the benzene extraction column (15) through a benzene extraction column top condenser (16), a benzene extraction column reflux tank (17), a benzene extraction column reflux pump (18) and a pipeline.

2. The pretreatment device for the caprolactam refining residual liquid according to claim 1, characterized by The solvent recovery column reboiler (7), the concentration column reboiler (13) and the benzene extraction column reboiler (19) are respectively communicated with a factory steam pipeline.

3. The pretreatment device for the caprolactam refining residual liquid according to claim 1, characterized by, The solvent recovery column reflux pump (6) is further communicated with a solvent treatment device (21) through a pipeline, the concentration column reflux pump (12) is further communicated with a sewage treatment device (22) through a pipeline, the benzene extraction column reflux pump (18) is further communicated with an ammonium sulfate crystallization device (23) through a pipeline, and the bottom of the benzene extraction column (15) is communicated with the sewage treatment device (22) through a benzene extraction column kettle pump (20).

4. The pretreatment device for the caprolactam refining residual liquid according to claim 1, characterized by, The raffinate tank (1), the solvent recovery column reflux tank (5), the concentration column reflux tank (11) and the benzene extraction column reflux tank (17) are communicated with a tail gas treatment device (24) through a pipeline.

5. The pretreatment device for the caprolactam refining residual liquid according to claim 1, wherein The solvent recovery column (3) and the concentration column (9) adopt an atmospheric column, the tray packing is wire mesh packing, 4-7 layers of packing are arranged, liquid nozzles are arranged on the reflux layer and the feed layer, liquid distributors are arranged above each layer of packing, and a mist eliminator is arranged on the top of the column.

6. The apparatus for pre-treating a caprolactam refining raffinate according to claim 1, wherein The benzene extraction column (15) is a rotating disc column and is provided with 5-8 layers of trays.

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