CN111686477A - Caprolactam extraction liquid washing tower, system and process - Google Patents

Caprolactam extraction liquid washing tower, system and process Download PDF

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Publication number
CN111686477A
CN111686477A CN202010613786.XA CN202010613786A CN111686477A CN 111686477 A CN111686477 A CN 111686477A CN 202010613786 A CN202010613786 A CN 202010613786A CN 111686477 A CN111686477 A CN 111686477A
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CN
China
Prior art keywords
caprolactam
tower
water
extraction
extraction liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010613786.XA
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Chinese (zh)
Inventor
蒋加新
楚守宾
付衍胜
耿维绪
肖杨
张晓辉
李国华
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Liaocheng Luxi Polyamide New Material Technology Co ltd
Original Assignee
Liaocheng Luxi Polyamide New Material Technology Co ltd
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Application filed by Liaocheng Luxi Polyamide New Material Technology Co ltd filed Critical Liaocheng Luxi Polyamide New Material Technology Co ltd
Priority to CN202010613786.XA priority Critical patent/CN111686477A/en
Publication of CN111686477A publication Critical patent/CN111686477A/en
Pending legal-status Critical Current

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D11/00Solvent extraction
    • B01D11/04Solvent extraction of solutions which are liquid
    • B01D11/0492Applications, solvents used

Abstract

The invention discloses a caprolactam extract washing tower, a system and a process, wherein the washing tower comprises a vertically arranged tower body, the inside of the tower body sequentially comprises an oil phase feeding distributor, a random packing layer, a water phase feeding distributor and a regular packing layer from bottom to top, a discharge hole of the oil phase feeding distributor is arranged upwards, a water outlet hole of the water phase feeding distributor is arranged downwards, the water phase feeding distributor is of a 'feng' shaped structure formed by a main water pipe and branch water pipes, the branch water pipes are provided with a plurality of water outlet holes, the bottom of the tower body is provided with a water phase outlet, and the top of the tower body is provided with an oil phase outlet. The invention can effectively remove inorganic salts and free acid in the caprolactam extraction liquid, reduce the conductivity of the caprolactam water solution and improve the quality of the caprolactam product.

Description

Caprolactam extraction liquid washing tower, system and process
Technical Field
The invention relates to a caprolactam extraction liquid washing tower, a system and a process.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
The traditional caprolactam refining process is that the caprolactam water solution with lower conductivity (generally less than 30 mus/cm) is obtained after benzene extraction and back extraction of the crude caprolactam water solution neutralized by ammonia water. At present, most caprolactam manufacturers adopt a neutralization crystallization process for saving energy and reducing consumption, the re-discharged liquid of a reaction unit directly reacts with gaseous ammonia to be separated to obtain a crude caprolactam water solution, and then benzene extraction and back extraction are carried out. However, the production practice of the inventor of the present invention finds that the crude caprolactam obtained by neutralization and crystallization has high inorganic salts and free acid, which seriously affect the extraction effect and the product quality and cause corrosion to equipment, and the conductivity of the aqueous caprolactam solution after back extraction is high.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a caprolactam extraction liquid washing tower, a system and a process, which can effectively remove inorganic salts and free acid in caprolactam extraction liquid, reduce the conductivity of a caprolactam water solution and improve the quality of a caprolactam product.
In order to achieve the purpose, the technical scheme of the invention is as follows:
on the one hand, a caprolactam extract scrubbing tower, including the tower body of vertical setting, by supreme oil phase feeding distributor, random packing layer, aqueous phase feeding distributor and the regular packing layer of including in proper order down in the tower body, the discharge gate of oil phase feeding distributor upwards sets up, and the apopore of aqueous phase feeding distributor sets up downwards, aqueous phase feeding distributor forms "rich" font structure by main water pipe and water pipe, and a plurality of apopores are seted up to the water pipe, and the tower body bottom sets up the aqueous phase export, and the tower body top sets up the oil phase export.
The invention provides a water phase feeding distributor, which enables the distribution of washing water to be more uniform, reduces the using amount of the washing water and reduces the loss of caprolactam. In order to effectively remove inorganic salts and free acid in the caprolactam extraction liquid, a random packing layer is arranged between an oil phase feeding distributor and a water phase feeding distributor to increase the oil-water mixing efficiency, so that the inorganic salts and the free acid are washed and removed, and in order to increase the separation of the waste water containing the inorganic salts and the free acid after washing from the oil phase, a regular packing layer is added on the upper part of the water phase feeding distributor to separate the oil from the water, so that the purposes of effectively removing the inorganic salts and the free acid in the caprolactam extraction liquid and reducing the conductivity of the caprolactam water solution are achieved.
On the other hand, the caprolactam extract washing system comprises a neutralization crystallizer, a benzene extraction tower, a back extraction tower and the caprolactam extract washing tower, wherein a liquid phase outlet of the neutralization crystallizer is connected with a product inlet of a benzene extraction tank, an oil phase outlet of the benzene extraction tank is connected with a feed inlet of an oil phase feeding distributor of the caprolactam extract washing tower, and a feed inlet of the back extraction tower is connected with an oil phase outlet of the caprolactam extract washing tower.
And a third aspect is a caprolactam extraction liquid washing process, which provides the caprolactam extraction liquid washing tower, wherein the caprolactam solution after the neutralization and crystallization is subjected to benzene extraction, the caprolactam extraction liquid after the benzene extraction enters the caprolactam extraction liquid washing tower to be washed by water to obtain the caprolactam extraction liquid after the water washing, and the caprolactam extraction liquid after the water washing is subjected to back extraction.
The invention has the beneficial effects that:
1. the regular packing layer and the random packing layer arranged in the washing tower are respectively positioned on the upper side and the lower side of the water phase feeding distributor, so that the conductivity of the caprolactam water solution can be effectively reduced, and the quality of caprolactam is improved.
2. The washing tower provided by the invention effectively reduces the acidity of an extraction system and reduces the corrosion to equipment.
3. The washing tower provided by the invention can automatically operate, and has the advantages of stronger operability, large load elasticity and stable operation.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of a caprolactam extraction liquid washing column of example 1 of the present invention;
wherein, the device comprises an oil phase feeding distributor, 2, a sieve plate, 3, a random packing layer, 4, a water phase feeding distributor, 5, a regular packing layer, 6 and a silk screen coalescer.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The invention provides a caprolactam extraction liquid washing tower, a system and a process, aiming at solving the problem of high inorganic salts and free acid in crude caprolactam caused by neutralization and crystallization.
The invention provides a caprolactam extract washing tower, which comprises a vertically arranged tower body, wherein the tower body sequentially comprises an oil phase feeding distributor, a random packing layer, a water phase feeding distributor and a regular packing layer from bottom to top, a discharge hole of the oil phase feeding distributor is upwards arranged, a water outlet hole of the water phase feeding distributor is downwards arranged, the water phase feeding distributor is in a 'feng' shaped structure formed by a main water pipe and branch water pipes, the branch water pipes are provided with a plurality of water outlet holes, the bottom of the tower body is provided with a water phase outlet, and the top of the tower body is provided with an oil phase outlet.
The invention provides a water phase feeding distributor, which enables the distribution of washing water to be more uniform, reduces the using amount of the washing water and reduces the loss of caprolactam. In order to effectively remove inorganic salts and free acid in the caprolactam extraction liquid, a random packing layer is arranged between an oil phase feeding distributor and a water phase feeding distributor to increase the oil-water mixing efficiency, so that the inorganic salts and the free acid are washed and removed, and in order to increase the separation of the waste water containing the inorganic salts and the free acid after washing from the oil phase, a regular packing layer is added on the upper part of the water phase feeding distributor to separate the oil from the water, so that the purposes of effectively removing the inorganic salts and the free acid in the caprolactam extraction liquid and reducing the conductivity of the caprolactam water solution are achieved.
In some examples of this embodiment, at least one screen plate is installed in the tower between the oil phase feed distributor and the random packing layer. Can provide mass transfer efficiency and increase the efficiency of removing inorganic salts and free acid in caprolactam extraction liquid.
In some embodiments of this embodiment, a wire mesh coalescer is mounted above the layer of structured packing. The water content in the oil phase can be reduced.
In some examples of this embodiment, the aqueous phase outlet at the bottom of the column is fitted with an in-line pH meter. The adjustment is convenient.
In some examples of this embodiment, a 38# intalox annular random packing is used in the random packing layer.
In some examples of this embodiment, the diameter of the outlet holes of the aqueous feed distributor is 1 to 2 mm.
The invention provides a caprolactam extraction liquid washing system, which comprises a neutralization crystallizer, a benzene extraction tower, a back extraction tower and the caprolactam extraction liquid washing tower, wherein a liquid phase outlet of the neutralization crystallizer is connected with a product inlet of a benzene extraction tank, an oil phase outlet of the benzene extraction tank is connected with a feed inlet of an oil phase feeding distributor of the caprolactam extraction liquid washing tower, and a feed inlet of the back extraction tower is connected with an oil phase outlet of the caprolactam extraction liquid washing tower.
Some examples of this embodiment include a stripping pump having an inlet connected to the oil phase outlet of the caprolactam extract scrubber and an outlet connected to the feed inlet of the stripping column.
In some examples of this embodiment, the aqueous phase outlet of the caprolactam extract wash column is connected to the product inlet of the benzene extraction column.
In a third embodiment of the present invention, a caprolactam extraction liquid washing process is provided, in which the caprolactam solution after neutralization and crystallization is subjected to benzene extraction in the caprolactam extraction liquid washing tower, the caprolactam extraction liquid after benzene extraction is fed into the caprolactam extraction liquid washing tower to be washed with water to obtain washed caprolactam extraction liquid, and the washed caprolactam extraction liquid is subjected to back extraction.
In some examples of this embodiment, the feed distributor has a water inlet pressure of 0.5 to 0.6MPa in the caprolactam extraction liquid washing column.
In some examples of this embodiment, the ratio of the washing water to the caprolactam extraction liquid in the caprolactam extraction liquid washing tower is 0.01-0.05: 1 by volume. According to the characteristics of caprolactam, the caprolactam is soluble in water and benzene (the solubility of the water is slightly larger than that of the benzene), but in the washing process of a washing tower, the water quantity is small, and the caprolactam is not dissolved after being saturated (the content of the caprolactam is 30-40 wt%). Meanwhile, the washing liquid is partially returned to the caprolactam extraction tower to recover caprolactam, so that the loss of caprolactam can be prevented.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.
Example 1
A caprolactam extract washing tower is shown in figure 1 and comprises a vertically arranged tower body, wherein the tower body sequentially comprises an oil phase feeding distributor 1, a plurality of sieve plates 2, a random packing layer 3, a water phase feeding distributor 4, a structured packing layer 5 and a silk screen coalescer 6 from bottom to top.
The discharge gate of oil phase feeding distributor 1 upwards sets up, and the apopore of aqueous phase feeding distributor 4 sets up downwards, and aqueous phase feeding distributor 4 forms "feng" font structure by main water pipe and a water pipe, and a plurality of diameters are 1 ~ 2 mm's apopore seted up to a water pipe, and the tower body bottom sets up the aqueous phase export, and the aqueous phase export is installed at the online pH meter, and the tower body top sets up the oil phase export. A38 # intalox saddle ring random packing is adopted in the random packing layer 3.
A caprolactam extraction liquid washing tower is arranged between a benzene extraction tower and a reverse extraction tower, the caprolactam extraction liquid of the caprolactam extraction tower is conveyed to the lower part of the caprolactam extraction liquid washing tower through a reverse extraction feed pump, desalted water is added in the upper half part of the tower, water distribution is carried out in a high-resistance water distribution mode, and the water inlet pressure is 0.5-0.6 Mpa; taking an extraction liquid (oil phase) as a dispersed phase in a caprolactam extraction liquid washing tower, and taking a washing liquid (water phase) as a continuous phase; the top discharge is refined extract liquid which enters a stripping tower, and the washing liquid at the bottom enters a benzene extraction tower to extract caprolactam.
When the washing tower operates, the water phase is a continuous phase, and the oil phase is a dispersed phase; the proportion of the water phase and the oil phase is controlled to be 0.01-0.05, the bottom extraction amount is controlled through a boundary position at the top of the washing tower, and the alkali adding amount of the front system is controlled through a pH value (5.5-10). The conductance of the washing tower after treatment is 10-15 mu s/cm; the acidity is controlled to be about 5 mmol/kg.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a caprolactam extract scrubbing tower, characterized by, includes the tower body of vertical setting, by supreme oil phase feeding distributor, random packing layer, aqueous phase feeding distributor and the regular packing layer of including in proper order down in the tower body, the discharge gate of oil phase feeding distributor upwards sets up, and the apopore of aqueous phase feeding distributor sets up downwards, aqueous phase feeding distributor forms "rich" font structure by main water pipe and water pipe, and a plurality of apopores are seted up to the water pipe, and the tower body bottom sets up the aqueous phase export, and the tower body top sets up the oil phase export.
2. The caprolactam extraction liquid washing column as claimed in claim 1, wherein at least one sieve plate is arranged in the column body between the oil phase feed distributor and the random packing layer.
3. The caprolactam extraction liquid washing column as claimed in claim 1, characterized in that a wire mesh coalescer is arranged above the layer of structured packing.
4. The caprolactam extraction liquid washing column as claimed in claim 1, wherein the aqueous phase outlet at the bottom of the column body is provided with an in-line pH meter.
5. The caprolactam extraction liquid washing column as claimed in claim 1, characterized in that a 38# intalox saddle ring random packing is used in the random packing layer.
6. The caprolactam extraction liquid washing column of claim 1, wherein the diameter of the water outlet of the water phase feed distributor is 1 to 2 mm.
7. A caprolactam extraction liquid washing system is characterized by comprising a neutralization crystallizer, a benzene extraction tower, a back extraction tower and the caprolactam extraction liquid washing tower as claimed in any one of claims 1 to 6, wherein a liquid phase outlet of the neutralization crystallizer is connected with a product inlet of a benzene extraction tank, an oil phase outlet of the benzene extraction tank is connected with a feed inlet of an oil phase feeding distributor of the caprolactam extraction liquid washing tower, and a feed inlet of the back extraction tower is connected with an oil phase outlet of the caprolactam extraction liquid washing tower.
8. The caprolactam extraction wash system of claim 7 wherein the aqueous phase outlet of the caprolactam extraction wash column is connected to the product inlet of the benzene extraction column.
9. A caprolactam extraction liquid washing process is characterized in that a caprolactam extraction liquid washing tower of any one of claims 1 to 6 is provided, benzene extraction is carried out on a caprolactam solution after neutralization and crystallization, the caprolactam extraction liquid after benzene extraction enters the caprolactam extraction liquid washing tower to be washed with water, a caprolactam extraction liquid after washing with water is obtained, and the caprolactam extraction liquid after washing with water is subjected to back extraction.
10. The process of claim 9, wherein the water inlet pressure of the distributor for feeding the aqueous phase into the washing column is 0.5-0.6 MPa.
CN202010613786.XA 2020-06-30 2020-06-30 Caprolactam extraction liquid washing tower, system and process Pending CN111686477A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010613786.XA CN111686477A (en) 2020-06-30 2020-06-30 Caprolactam extraction liquid washing tower, system and process

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Application Number Priority Date Filing Date Title
CN202010613786.XA CN111686477A (en) 2020-06-30 2020-06-30 Caprolactam extraction liquid washing tower, system and process

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Publication Number Publication Date
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Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013640A (en) * 1974-04-11 1977-03-22 Union Carbide Corporation Process for the recovery of amides
CN1216528A (en) * 1996-02-23 1999-05-12 Dsm有限公司 Process to prepare 'epsilon'-caprolactam from 6-aminocaproic acid
CN1535263A (en) * 2001-03-01 2004-10-06 Dsm Ip 财产有限公司 Process for recovering and purifying caprolactam from organic solvent
CN102143945A (en) * 2008-09-04 2011-08-03 帝斯曼知识产权资产管理有限公司 Washing of an organic phase comprising caprolactam
CN102755823A (en) * 2012-08-10 2012-10-31 江山市泰格化工有限公司 Method for desulfurizing high-sulphur boiler flue gas to prepare high-purity ammonium bisulfite
CN103379948A (en) * 2011-01-18 2013-10-30 荷兰能源建设基金中心 Heat integrated distillation column using structured packing
CN104072419A (en) * 2013-10-28 2014-10-01 中国石油化工股份有限公司 Purification method and purification device of caprolactam
CN105498284A (en) * 2015-12-04 2016-04-20 中国天辰工程有限公司 Extracting tower for liquid-liquid heterogeneous separation
CN107216274A (en) * 2017-05-31 2017-09-29 湖北三宁化工股份有限公司 The system and method for the continuous removing impurities of solvent benzol in a kind of caprolactam extraction process
CN107556240A (en) * 2016-08-24 2018-01-09 沧州旭阳化工有限公司 A kind of system of caprolactam refining method and refined caprolactam
CN109157866A (en) * 2018-10-22 2019-01-08 上海灿越化工科技有限公司 To the method and apparatus of caprolactam crude oil extraction
CN109621466A (en) * 2018-12-17 2019-04-16 宋心红 A kind of system and method for new caprolactam water solution evaporation production caprolactam
CN109694349A (en) * 2017-10-24 2019-04-30 中国石油化工股份有限公司 A kind of method of caprolactam refining

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013640A (en) * 1974-04-11 1977-03-22 Union Carbide Corporation Process for the recovery of amides
CN1216528A (en) * 1996-02-23 1999-05-12 Dsm有限公司 Process to prepare 'epsilon'-caprolactam from 6-aminocaproic acid
CN1535263A (en) * 2001-03-01 2004-10-06 Dsm Ip 财产有限公司 Process for recovering and purifying caprolactam from organic solvent
CN102143945A (en) * 2008-09-04 2011-08-03 帝斯曼知识产权资产管理有限公司 Washing of an organic phase comprising caprolactam
CN103379948A (en) * 2011-01-18 2013-10-30 荷兰能源建设基金中心 Heat integrated distillation column using structured packing
CN102755823A (en) * 2012-08-10 2012-10-31 江山市泰格化工有限公司 Method for desulfurizing high-sulphur boiler flue gas to prepare high-purity ammonium bisulfite
CN104072419A (en) * 2013-10-28 2014-10-01 中国石油化工股份有限公司 Purification method and purification device of caprolactam
CN105498284A (en) * 2015-12-04 2016-04-20 中国天辰工程有限公司 Extracting tower for liquid-liquid heterogeneous separation
CN107556240A (en) * 2016-08-24 2018-01-09 沧州旭阳化工有限公司 A kind of system of caprolactam refining method and refined caprolactam
CN107216274A (en) * 2017-05-31 2017-09-29 湖北三宁化工股份有限公司 The system and method for the continuous removing impurities of solvent benzol in a kind of caprolactam extraction process
CN109694349A (en) * 2017-10-24 2019-04-30 中国石油化工股份有限公司 A kind of method of caprolactam refining
CN109157866A (en) * 2018-10-22 2019-01-08 上海灿越化工科技有限公司 To the method and apparatus of caprolactam crude oil extraction
CN109621466A (en) * 2018-12-17 2019-04-16 宋心红 A kind of system and method for new caprolactam water solution evaporation production caprolactam

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