Device for refining and back-extracting caprolactam

Abstract

The utility model discloses a device for refining and back-extracting caprolactam. The device comprises a tower body and a sieve tray positioned in the tower body, wherein the sieve tray is not provided with a weir height; the tower body is sequentially provided with a water phase inlet, a crude benzene outlet, a caprolactam crude solution feeding hole and a caprolactam refined solution discharging hole from top to bottom; a crude solution feeding distributor is arranged at the caprolactam crude solution feeding hole, and the crude solution feeding distributor is a dendritic distributor. The device disclosed by the utility model adopts a sieve plate form, and has the characteristics of less accessory equipment, simplicity in operation, low investment, low energy consumption, stability in operation, high caprolactam yield and the like compared with the traditional pulse ceramic packing.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of chemical equipment, concretely relates to a device and method for caprolactam refining back extraction. BACKGROUND

[0002] Caprolactam is an important organic chemical raw material, and is mainly used for manufacturing nylon 6 as a chemical fiber monomer. There are various production methods of caprolactam, and at present, the mainstream is the cyclohexanone-hydroxylamine method and the cyclohexanone ammonium oxime method taking benzene as a raw material. The existing caprolactam separation and refining process generally comprises benzene extraction, water back extraction and the like. Most of the impurities are removed in benzene extraction, and water back extraction is used to realize the circulation of the extraction agent benzene.

[0003] At present, the back extraction tower in the industry mainly adopts a pulse ceramic saddle ring filler tower, which is divided into two sections of fillers, and is provided with a set of pulse rotary valves, four buffer tanks and two circulating pumps at the bottom. The rotary valve machine is sealed with water, the pulse rotary valve and the circulating pump are started, and a certain liquid level in the pulse buffer tank is maintained, so that periodic liquid level rise and fall in the tower are generated, and the rise and fall amplitude is controlled within 10-20mm, so as to strengthen the extraction effect. The benzene-caprolactam solution is added from the bottom of the back extraction tower, the extraction process water is added from the top of the back extraction tower, the benzene-caprolactam solution and the process condensate are countercurrently extracted under the action of the pulse device, the caprolactam-water solution flows out from the bottom of the tower, and the benzene overflows from the top of the tower into the product tank area crude benzene tank.

[0004] The existing process has the following shortcomings: ①complicated operation, many auxiliary equipment, large investment; ②high energy consumption and material consumption, large power consumption and process water consumption, and high content of caprolactam in benzene at the top; ③unstable operation, ceramic fillers are easy to break, causing the rotary valve machine to leak, the circulating pump filter to be blocked, and the pump to be damaged, etc. UTILITY MODEL CONTENTS

[0005] The utility model aims at overcoming the problems of complicated operation, many auxiliary equipment, large investment, high energy consumption and low caprolactam yield in the prior art, and provides a device for caprolactam refining back extraction, which has the characteristics of less auxiliary equipment, simple operation, small investment, low energy consumption, stable operation and high caprolactam yield.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a device for caprolactam refining back extraction, which comprises a tower body and a sieve plate tray located in the interior of the tower body, wherein the sieve plate tray is not provided with a weir; the tower body is sequentially provided with a water phase inlet, a crude benzene outlet, a caprolactam crude solution feeding port and a caprolactam refined solution discharging port from top to bottom; a crude solution feeding distributor is arranged at the caprolactam crude solution feeding port, and the crude solution feeding distributor is a dendritic distributor.

[0007] The beneficial technical effects achieved by the technical scheme are as follows:

[0008] (1) The device for refining and back-extracting caprolactam provided by the utility model adopts sieve plate tower as benzene hexyl liquid back-extraction tower, the crude solution feed distributor is set as dendritic shape, the contact area of caprolactam crude solution and water phase is increased, and the extraction efficiency is better achieved.

[0009] (2) The device has the characteristics of less auxiliary equipment, simple operation, small investment, low energy consumption, stable operation, high caprolactam yield and the like. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a structure schematic view of a device for refining and back-extracting caprolactam provided by an embodiment of the utility model;

[0011] Figure 2 is a structure schematic view of a sieve plate tray provided by an embodiment of the utility model;

[0012] Figure 3 is a structure schematic view of a dendritic distributor provided by an embodiment of the utility model.

[0013] BRIEF DESCRIPTION OF DRAWINGS

[0014] 1 tower body 2 sieve plate tray 3 crude solution feed distributor

[0015] 21 rectangular plate one 22 rectangular plate two 23 arcuate plate

[0016] 24 channel plate one 25 channel plate two 26 handle

[0017] 31 main pipe 32 branch pipe 33 main pipe blanking plate

[0018] 34 branch pipe blanking plate 35 connecting plate 36 flange

[0019] A water phase inlet B crude benzene outlet C caprolactam crude solution feed port

[0020] D caprolactam refined solution discharge port DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not to be construed as limited. The ranges and values are to be understood as approximations. The endpoints of the ranges and values are provided as a separate point for purposes of clarity. The ranges and values are understood to encompass any and all sub-ranges that fall within the given range or value. For example, every range of values between about 1 and about 10, is understood to include the value of 1 or 10, or any other value or sub-range between about 1 and about 10, even though these values and sub-ranges are not expressly stated.

[0022] The utility model discloses a device for the counter-extraction of caprolactam refining, as Figure 1 shown. The device comprises: a tower body 1 and a sieve tray 2 located inside the tower body; the sieve tray 2 is not provided with a weir height; the tower body 1 is sequentially provided with an aqueous phase inlet A, a crude benzene outlet B, a crude caprolactam solution feed inlet C and a refined caprolactam solution discharge outlet D from top to bottom; a crude solution feed distributor 3 is arranged at the crude caprolactam solution feed inlet C, and the crude solution feed distributor 3 is a dendritic distributor.

[0023] In the utility model, the discharge outlet of the crude solution feed distributor 3 is arranged upward.

[0024] The utility model first changes the benzene-caprolactam solution counter-extraction tower from traditional pulsed ceramic packing to a sieve tray tower. This tray does not need to set a weir height to avoid liquid accumulation; and by setting the crude solution feed distributor at the crude caprolactam solution feed inlet as a dendritic distributor, the contact area between the crude caprolactam solution and the aqueous phase is increased to better achieve the extraction efficiency.

[0025] The device of the utility model adopts a sieve tray form, without causing periodic liquid level rise and fall in the tower. The benzene-caprolactam solution is added from the bottom of the tower, and the extraction process water is added from the top of the tower. The benzene-caprolactam solution and the process water perform countercurrent extraction in the sieve tray tower. The caprolactam-aqueous solution flows out from the bottom of the tower, and benzene overflows from the top of the tower and enters the crude benzene tank in the product tank area (as Figure 1 shown).

[0026] A schematic structural view of a sieve tray proposed by an embodiment of the utility model, as Figure 2 shown. Among them, the sieve tray comprises a rectangular plate one 21, a rectangular plate two 22, an arched plate 23, a channel plate one 24, a channel plate two 25 and a handle 26.

[0027] A schematic structural view of a dendritic distributor proposed by an embodiment of the utility model, as Figure 3 shown. Among them, the dendritic distributor comprises a main pipe 31, branch pipes 32, a main pipe blanking plate 33, branch pipe blanking plates 34, a connecting plate 35 and a flange 36; the main pipe 31 and the branch pipes 32 are arranged in a "rich" shape, with the main pipe 31 in the middle and the branch pipes 32 symmetrically arranged on both sides of the main pipe 31.

[0028] According to the utility model, since the solubility of caprolactam in water is greater than that in benzene, after multiple extractions through multiple tower plates, caprolactam is almost completely concentrated in the water solvent, and benzene almost does not contain caprolactam, achieving efficient extraction.

[0029] According to some embodiments of the utility model, the tower liquid flow number of the device is set to single liquid flow.

[0030] According to some embodiments of the present application, the number of sieve trays 2 is 30-60.

[0031] According to the present application, the number of sieve trays 2 is within the above range, which can ensure the stripping yield.

[0032] According to some preferred embodiments of the present application, the number of sieve trays 2 is 45-55.

[0033] According to the present application, the number of sieve trays 2 is within the above range, which can further improve the stripping yield.

[0034] According to some embodiments of the present application, the opening rate of the sieve trays 2 is 3-10%.

[0035] According to some preferred embodiments of the present application, the opening rate of the sieve trays 2 is 4-8%.

[0036] According to the present application, the opening rate of the sieve trays 2 is within the above range, which can ensure the stripping efficiency, and too large or too small opening rate will directly affect the stripping efficiency.

[0037] According to some embodiments of the present application, the opening diameter of the sieve trays 2 is 2-10mm.

[0038] According to some preferred embodiments of the present application, the opening diameter of the sieve trays 2 is 4-8mm.

[0039] According to the present application, the opening diameter of the sieve trays 2 is within the above range, which can ensure the entrainment efficiency, and too large or too small opening diameter will easily cause serious entrainment at the top and excessive loss of caprolactam, thus the opening rate needs to be controlled.

[0040] According to some embodiments of the present application, the height-diameter ratio of the tower body 1 is 7-16:1.

[0041] According to the present application, the height-diameter ratio of the tower body 1 is within the above range, which can ensure the processing capacity of the tower body device and the fluid distribution and mass transfer efficiency.

[0042] According to some preferred embodiments of the present application, the height-diameter ratio of the tower body 1 is 10-13:1.

[0043] According to the present application, the height-diameter ratio of the tower body 1 is within the above range, which can further improve the processing capacity of the tower body device and ensure the fluid distribution and mass transfer efficiency.

[0044] According to some preferred embodiments of the present application, the tower height of the tower body 1 is 25-40m, and the diameter is 2.5-3.5m.

[0045] In some particularly preferred embodiments, the refining of caprolactam is carried out by using the device shown in Figure 1 The device for refining caprolactam by reverse extraction is shown in the figure, which comprises a tower body 1 and sieve trays 2 inside the tower body, wherein the height of the tower body is 25-40 m, the diameter is 2.5-3.5 m, the number of trays is 30-60 layers, the opening diameter of the trays is 2-10 mm, and the opening rate is 3-10%. The tower liquid flow number is single liquid flow, and the trays do not need to be provided with weir heights. The benzene-caprolactam solution feeding distributor is provided as a dendritic distributor with an opening diameter of 10 mm. The mass ratio of the extractant (water) to the benzene-caprolactam solution is controlled to be 1:2-1:10, the extraction temperature is 25-50°C, and the extraction time is 30-60 minutes, so as to carry out liquid-liquid extraction of the extractant and the benzene-caprolactam solution. Since the solubility of caprolactam in water is greater than that in benzene, after multiple extractions through multiple trays, caprolactam is almost completely concentrated in the water solvent, and benzene almost does not contain caprolactam. Finally, the discharge indicators are measured, and the average content of caprolactam in the top benzene is less than 0.005 wt%, and the average content of benzene in the bottom caprolactam water solution is less than or equal to 2 wt%.

[0046] In the above scheme, the mass ratio of the extractant (water) to the benzene-caprolactam solution is 1:2-1:10, preferably 1:3.5.

[0047] In the above scheme, the extraction temperature is 25-50°C, preferably 40°C.

[0048] In the above scheme, the extraction time is 30-60 minutes, preferably 45 minutes.

[0049] In the above scheme, the height of the plate extraction tower is 25-40 m, preferably 33-37 m.

[0050] In the above scheme, the diameter of the plate extraction tower is 2.5-3.5 m, preferably 2.8-3.3 m.

[0051] In the above scheme, the number of trays of the plate extraction tower is 30-60 layers, preferably 45-55 layers.

[0052] In the above scheme, the opening diameter of the plate extraction tower is 2-10 mm, preferably 4-8 mm.

[0053] In the above scheme, the opening rate of the plate extraction tower is 3-10%, preferably 4-8%.

[0054] Compared with the commonly used pulse ceramic matrix saddle ring packed column as a reverse extraction tower, the device has the following advantages:

[0055] ① Simple operation, less auxiliary equipment, small investment;

[0056] ②Consumption is low, and the original power consumption and machine seal water consumption are large, wherein the power of the pulser is 4kw / h, the power of the circulating pump is 75kw / h, the machine seal water consumption of the rotary valve is 1t / h, the original ceramic filler is easy to break, causing the machine seal leakage of the rotary valve, and the filter of the circulating pump is blocked;

[0057] ③The index is excellent, the benzene in the top of the back-extraction tower contains about 1000ppm of hexyl, which is reduced to less than 100ppm, the benzene in the hexyl water contains the same as the original form, and the product yield is greatly improved;

[0058] ④The operation is stable, the original ceramic filler is easy to break, causing the machine seal leakage of the rotary valve, and the filter of the circulating pump is blocked, causing the pump damage.

[0059] In the caprolactam refining unit, the sieve plate type back-extraction tower of the utility model is used in the benzene-hexyl liquid back-extraction tower, instead of the original ceramic filler pulse tower, the extraction effect is obviously higher than that of the original traditional ceramic filler pulse tower, the average value of the benzene in the top is reduced, about 1164t of caprolactam is saved per year, the circulating pump and the pulse rotary valve stop running, 1.28 million KWh of electricity fee is saved per year, 157t of standard coal is saved, through more than one year of operation, the economic benefit is very considerable.

[0060] The device of the utility model avoids the problems of the traditional pulse ceramic filler, such as easy to break, causing the machine seal leakage of the rotary valve, the filter of the circulating pump is blocked, and the pump is damaged; compared with the traditional pulse ceramic filler, the device has the characteristics of less auxiliary equipment, simple operation, small investment, low energy consumption, stable operation, and high caprolactam yield.

[0061] The preferred embodiments of the utility model are described in detail above, but the utility model is not limited to this. Within the technical concept range of the utility model, the technical scheme of the utility model can be variously modified, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the utility model, and all belong to the protection range of the utility model.

Claims

1. An apparatus for caprolactam purification back extraction, characterized by, The device comprises a tower body and sieve trays located inside the tower body; wherein the sieve trays are not provided with weir height; the tower body is sequentially provided with water phase inlet, crude benzene outlet, caprolactam crude solution feeding port and caprolactam refined solution discharge port from top to bottom; the crude solution feeding distributor is provided at the caprolactam crude solution feeding port, and the crude solution feeding distributor is a dendritic distributor.

2. The apparatus of claim 1, wherein, The number of tower liquid flow processes of the device is set as single liquid flow.

3. The apparatus of claim 1, wherein, The number of the sieve trays is 30-60 layers.

4. The apparatus of claim 3, wherein, The number of the sieve trays is 45-55 layers.

5. The apparatus of claim 1, wherein, The open hole rate of the sieve trays is 3-10%.

6. The apparatus of claim 5, wherein, The open hole rate of the sieve trays is 4-8%.

7. The apparatus of claim 1, wherein, The open hole diameter of the sieve trays is 2-10mm.

8. The apparatus of claim 7, wherein, The open hole diameter of the sieve trays is 4-8mm.

9. The apparatus of claim 1, wherein, The height-diameter ratio of the tower body is 7-16:

1.

10. The apparatus of claim 9, wherein, The height-diameter ratio of the tower body is 10-13:1.

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