阅读说明：本技术 液液分离系统及分离方法 (Liquid-liquid separation system and separation method ) 是由 路冬永 孔利丰 王仕超 常仕雷 孙程远 张连庆 穆志刚 于 2019-10-11 设计创作，主要内容包括：本发明实施例提供一种液液分离系统及分离方法,液液分离系统包括串联的一级分离装置和二级分离装置,所述二级分离装置包括第一分离器、第二分离器、第三分离器和第四分离器,其中,所述第一分离器和第三分离器串联,所述第二分离器和第四分离器串联,且串联后的所述第一分离器和第三分离器与串联后的所述第二分离器和第四分离器并联。本发明能够实现三级分离,提高分离效果,解决了工艺生产中有机相带碱的问题,防止后续工序的设备结垢,延长生产周期,提高经济效益。(The embodiment of the invention provides a liquid-liquid separation system and a separation method, wherein the liquid-liquid separation system comprises a first-stage separation device and a second-stage separation device which are connected in series, the second-stage separation device comprises a first separator, a second separator, a third separator and a fourth separator, the first separator and the third separator are connected in series, the second separator and the fourth separator are connected in series, and the first separator and the third separator which are connected in series are connected in parallel with the second separator and the fourth separator which are connected in series. The invention can realize three-stage separation, improve the separation effect, solve the problem of alkali carried in an organic phase in the process production, prevent equipment scaling of subsequent procedures, prolong the production period and improve the economic benefit.)

1. The liquid-liquid separation system is characterized by comprising a first-stage separation device and a second-stage separation device which are connected in series, wherein the second-stage separation device comprises a first separator, a second separator, a third separator and a fourth separator, the first separator and the third separator are connected in series, the second separator and the fourth separator are connected in series, and the first separator and the third separator are connected in series and the second separator and the fourth separator are connected in parallel.

2. The liquid-liquid separation system of claim 1, wherein the primary separation device is a separator, the primary separation device has a liquid inlet, an oil phase outlet and a water phase outlet, and the liquid inlet is connected with the liquid outlet of the decomposition reaction kettle; the oil phase outlet is respectively connected with the first separator and the second separator through oil phase pipelines; and the water phase outlet is respectively connected with the decomposition reaction kettle and the waste alkali evaporation system.

3. The liquid-liquid separation system of claim 1, wherein the first separator and the second separator have an inlet, an oil phase outlet and an aqueous phase outlet, respectively, the inlet being connected to the oil phase outlet of the primary separation device; the oil phase outlet of the first separator is communicated with the liquid inlet of the third separator; the oil phase outlet of the second separator is communicated with the liquid inlet of the fourth separator; and the water phase outlet of the first separator and the water phase outlet of the second separator are respectively connected to a decomposition reaction kettle, a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series.

4. The liquid-liquid separation system of claim 1, wherein the third separator and the fourth separator have an oil phase outlet and an aqueous phase outlet, respectively, and the oil phase outlet of the third separator and the oil phase outlet of the fourth separator are both connected to an alkane column; the water phase outlet of the third separator is respectively connected to a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series; and a water phase outlet of the fourth separator is respectively connected to a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series.

5. The liquid-liquid separation system according to claim 1, further comprising a primary water washing pump disposed on a first circulation pipeline, wherein one end of the first circulation pipeline is connected to the water phase outlet of the third separator and the water phase outlet of the fourth separator, and the other end of the first circulation pipeline is connected to a pipeline for connecting the primary separation device and the secondary separation device in series.

6. The liquid-liquid separation system according to claim 1, further comprising a secondary water washing pump disposed on a second circulation line, one end of the second circulation line being connected to the aqueous phase outlet of the first separator and the aqueous phase outlet of the second separator, and the other end of the second circulation line being connected to a line for connecting the primary separation device and the secondary separation device in series.

7. The liquid-liquid separation system according to claim 1, further comprising a primary washing pump and a secondary washing pump, wherein an inlet of the primary washing pump is connected with the water phase outlets of the third separator and the fourth separator, an outlet of the primary washing pump is connected with an inlet of the secondary washing pump, the water phase outlets of the first separator and the second separator are respectively connected with an inlet of the secondary washing pump, and an outlet of the secondary washing pump is connected with a pipeline for connecting the primary separating device and the secondary separating device in series.

8. The liquid-liquid separation system of claim 1, wherein a water inlet pipeline is provided on the pipeline connecting the first separator and the third separator in series and the pipeline connecting the second separator and the fourth separator in series.

9. the liquid-liquid separation system of claim 8 wherein a mixer is disposed on the pipeline connecting the first-stage separator and the second-stage separator in series, the pipeline connecting the first separator and the third separator in series, and the pipeline connecting the second separator and the fourth separator in series, respectively, wherein the mixer on the pipeline connecting the first separator and the third separator in series is located downstream of the water inlet pipeline connected thereto, and the mixer on the pipeline connecting the second separator and the fourth separator in series is located downstream of the water inlet pipeline connected thereto.

10. A liquid-liquid separation method comprising:

The method comprises the following steps that a to-be-separated liquid containing a water phase and an oil phase from a decomposition reaction kettle firstly enters a first-stage separation device for primary separation, the water phase and the oil phase are separated, wherein one part of the water phase enters a waste alkali evaporation system, the other part of the water phase circulates back to the decomposition reaction kettle, and the oil phase enters a second-stage separation device connected with the first-stage separation device in series for secondary separation;

the oil phase separated by the first-stage separation device is divided into two paths to respectively enter a first separator and a second separator which are connected in parallel of the second-stage separation device;

The oil phase separated by the first separator enters a third separator connected in series with the first separator, and the oil phase separated by the second separator enters a fourth separator connected in series with the second separator; the water phase separated by the first separator and the second separator is divided into three parts, one part enters a waste alkali evaporation system, the other part is circulated back to the decomposition reaction kettle, and the other part is circulated back to a pipeline which is used for connecting the first-stage separation device and the second-stage separation device in series so as to be divided into two paths again and respectively enter the first separator and the second separator for separation;

And the oil phase separated by the third separator and the fourth separator enters an alkane tower, the separated water phase is divided into two parts, one part enters a waste alkali evaporation system, and the other part is recycled and used for being connected with a pipeline for connecting the first-stage separation device and the second-stage separation device in series so as to be separated by being divided into two paths again and then respectively enter the first separator and the second separator for separation.

Technical Field

The invention belongs to the field of chemical industry, and particularly relates to a liquid-liquid separation system and a separation method.

background

liquid-liquid separation is a common process in the chemical field, and substances achieve the effect of two-phase separation through a separator.

At present, in the domestic process for producing cyclohexanone by an oxidation method, cyclohexane oxidation liquid is directionally decomposed under an alkaline condition to generate cyclohexanone and cyclohexanol, and organic matters and inorganic matters are subjected to liquid-liquid separation and then enter an alkane distillation system to obtain crude alcohol ketone. Because cyclohexane can dissolve a certain amount of saturated water, the decomposition liquid carries a small amount of alkali liquor, so that the reboiler of the alkane-one tower is scaled, and the reboiler needs to be shut down to clean the alkali scale after the operation for a period of time. The problems of poor waste alkali separation effect, scaling of an alkane tower reboiler and the like exist in the industrial production of cyclohexanone. In order to solve the problems, in the prior art, organic phase is washed once in the tail separation section, but trace inorganic metal ions are still carried into the next procedure (alkane tower procedure) along with saturated water after washing, so that the tube nest of a reboiler of the alkane tower is scaled, and the requirement of long-period operation of the device cannot be met.

disclosure of Invention

in view of the above problems in the prior art, an object of the embodiments of the present invention is to provide a method for reducing the content of water phase in the separated oil phase with high separation efficiency.

The liquid-liquid separation system is characterized by comprising a first-stage separation device and a second-stage separation device which are connected in series, wherein the second-stage separation device comprises a first separator, a second separator, a third separator and a fourth separator, the first separator and the third separator are connected in series, the second separator and the fourth separator are connected in series, and the first separator and the third separator which are connected in series are connected in parallel with the second separator and the fourth separator which are connected in series.

In some embodiments, the first-stage separation device is a separator, the first-stage separation device has a liquid inlet, an oil phase outlet and a water phase outlet, and the liquid inlet is connected with the liquid outlet of the decomposition reaction kettle; the oil phase outlet is respectively connected with the first separator and the second separator through oil phase pipelines; and the water phase outlet is respectively connected with the decomposition reaction kettle and the waste alkali evaporation system.

In some embodiments, the first separator and the second separator have a liquid inlet, an oil phase outlet and a water phase outlet, respectively, the liquid inlets being connected with the oil phase outlet of the primary separation device; the oil phase outlet of the first separator is communicated with the liquid inlet of the third separator; the oil phase outlet of the second separator is communicated with the liquid inlet of the fourth separator; and the water phase outlet of the first separator and the water phase outlet of the second separator are respectively connected to a decomposition reaction kettle, a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series.

In some embodiments, the third separator and the fourth separator have an oil phase outlet and an aqueous phase outlet, respectively, both of which are connected to an alkane column; the water phase outlet of the third separator is respectively connected to a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series; and a water phase outlet of the fourth separator is respectively connected to a waste alkali evaporation system and a pipeline for connecting the primary separation device and the secondary separation device in series.

In some embodiments, the liquid-liquid separation system further includes a primary water washing pump disposed on a first circulation pipeline, one end of the first circulation pipeline is connected to the water phase outlet of the third separator and the water phase outlet of the fourth separator, and the other end of the first circulation pipeline is connected to a pipeline for connecting the primary separation device and the secondary separation device in series.

In some embodiments, the liquid-liquid separation system further comprises a secondary water washing pump, the secondary water washing pump is disposed on a second circulation pipeline, one end of the second circulation pipeline is connected with the water phase outlet of the first separator and the water phase outlet of the second separator, and the other end of the second circulation pipeline is connected with a pipeline for connecting the primary separation device and the secondary separation device in series.

In some embodiments, the liquid-liquid separation system further comprises a primary water washing pump and a secondary water washing pump, an inlet of the primary water washing pump is connected with water phase outlets of the third separator and the fourth separator, an outlet of the primary water washing pump is connected with an inlet of the secondary water washing pump, water phase outlets of the first separator and the second separator are respectively connected with an inlet of the secondary water washing pump, and an outlet of the secondary water washing pump is connected with a pipeline for connecting the primary separating device and the secondary separating device in series.

In some embodiments, a water inlet pipeline is respectively arranged on the pipeline in series connection with the first separator and the third separator and the pipeline in series connection with the second separator and the fourth separator.

In some embodiments, a pipeline of the first-stage separation device connected in series with the second-stage separation device, a pipeline of the first separator and the third separator connected in series, and a pipeline of the second separator and the fourth separator connected in series are respectively provided with a mixer, the mixer on the pipeline of the first separator and the third separator connected in series is located downstream of the water inlet pipeline connected thereto, and the mixer on the pipeline of the second separator and the fourth separator connected in series is located downstream of the water inlet pipeline connected thereto.

The embodiment of the invention also provides a liquid-liquid separation method, which comprises the following steps:

The method comprises the following steps that a to-be-separated liquid containing a water phase and an oil phase from a decomposition reaction kettle firstly enters a first-stage separation device for primary separation, the water phase and the oil phase are separated, wherein one part of the water phase enters a waste alkali evaporation system, the other part of the water phase circulates back to the decomposition reaction kettle, and the oil phase enters a second-stage separation device connected with the first-stage separation device in series for secondary separation;

The oil phase separated by the first-stage separation device is divided into two paths to respectively enter a first separator and a second separator which are connected in parallel of the second-stage separation device;

the oil phase separated by the first separator enters a third separator connected in series with the first separator, and the oil phase separated by the second separator enters a fourth separator connected in series with the second separator; the water phase separated by the first separator and the second separator is divided into three parts, one part enters a waste alkali evaporation system, the other part is circulated back to the decomposition reaction kettle, and the other part is circulated back to a pipeline which is used for connecting the first-stage separation device and the second-stage separation device in series so as to be divided into two paths again and respectively enter the first separator and the second separator for separation;

And the oil phase separated by the third separator and the fourth separator enters an alkane tower, the separated water phase is divided into two parts, one part enters a waste alkali evaporation system, and the other part is recycled and used for being connected with a pipeline for connecting the first-stage separation device and the second-stage separation device in series so as to be separated by being divided into two paths again and then respectively enter the first separator and the second separator for separation.

Compared with the prior art, the liquid-liquid separation system and the separation method provided by the embodiment of the invention adopt a two-section series connection separation mode, the latter section series connection comprises two-section parallel connection separation, each section parallel connection comprises two series connection separation respectively, three-stage separation is realized, the separation effect is improved, the problem that cyclohexane carries alkali in industrial production of cyclohexanone is solved, the fouling of a column pipe of an alkane tower reboiler is prevented, the production period is prolonged, and the economic benefit is improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

the summary of various implementations or examples of the technology described in this disclosure is not a comprehensive disclosure of the full scope or all features of the disclosed technology.

Drawings

In the drawings, which are not necessarily drawn to scale, like reference numerals may describe similar components in different views. Like reference numerals having letter suffixes or different letter suffixes may represent different instances of similar components. The drawings illustrate various embodiments, by way of example and not by way of limitation, and together with the description and claims, serve to explain the inventive embodiments. The same reference numbers will be used throughout the drawings to refer to the same or like parts, where appropriate. Such embodiments are illustrative, and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

Fig. 1 is a schematic structural view of a liquid-liquid separation system according to an embodiment of the present invention.

Reference numerals:

1-a first stage separation device; 2-a first separator; 3-a second separator; 4-a third separator; 5-a fourth separator; 6-first oil phase pipeline; 7-a first aqueous phase line; 8-a second aqueous phase line; 9-a second oil phase pipeline; 10-a third oil phase line; 11-a third aqueous phase line; 12-a fourth aqueous phase line; 13-a fifth aqueous phase line; 14-a sixth aqueous phase line; 15-a seventh aqueous phase line; 16-an eighth aqueous phase line; 17-a ninth aqueous phase line; 18-tenth aqueous phase line; 19-an eleventh aqueous phase line; 20-a twelfth aqueous phase line; 21-first-stage water washing pump; 22-a secondary water washing pump; 23-a first circulation line; 24-a second circulation line; 25-a water inlet pipeline; 26-a first mixer; 27-a second mixer; 28-third mixer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first" and "second" herein does not denote any order, quantity, or importance, but rather the terms first and second are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

To maintain the following description of the embodiments of the present invention clear and concise, a detailed description of known functions and known components of the invention have been omitted.

The embodiment of the invention discloses a liquid-liquid separation system, which can be used for separating a water phase and an oil phase of mixed liquid before entering an alkane tower in a process for producing cyclohexanone by an oxidation method, for example. As shown in fig. 1, the liquid-liquid separation system according to the embodiment of the present invention includes a first-stage separation device 1 and a second-stage separation device connected in series, where the second-stage separation device includes a first separator 2, a second separator 3, a third separator 4, and a fourth separator 5, where the first separator 2 and the third separator 4 are connected in series, the second separator 3 and the fourth separator 5 are connected in series, and the first separator 2 and the third separator 4 connected in series are connected in parallel with the second separator 3 and the fourth separator 5 connected in series.

the liquid-liquid separation system of the embodiment of the invention combines a plurality of separators together in two connection modes of series connection and parallel connection, realizes three-stage separation, improves the separation efficiency, and reduces the content of a water phase (such as sodium ions) in an oil phase; the cyclohexanone production process is beneficial to the subsequent procedures, protects the alkane tower, reduces the scaling possibility of the alkane tower and prolongs the service life.

in some embodiments, the first-stage separation device 1 is a separator, and the specific structure of the separator is not limited as long as separation of the oil phase and the water phase can be achieved. As shown in fig. 1, the first-stage separation device 1 has a liquid inlet, an oil phase outlet and a water phase outlet, the liquid inlet is connected to the liquid outlet of the decomposition reaction kettle, and the oil phase outlet is connected to the first separator 2 and the second separator 3 through oil phase pipelines, so that the oil phase separated by the first-stage separation device 1 enters the first separator 2 and the second separator 3 in two ways to continuously separate the water phase from the oil phase; the water phase outlet is connected with the decomposition reaction kettle through a first water phase pipeline 7 so that a part of decomposed water phase circulates back to the decomposition reaction kettle for reaction and enters the first-stage separation device 1, and the water phase outlet is also connected with the alkali waste evaporation system through a second water phase pipeline 8 so that the other part of decomposed water phase enters the alkali waste evaporation system for evaporation and recovery. It should be noted that: the separator is equipped with remote and on-site level meter, when the level rises, the water phase is firstly returned to the decomposing kettle to provide phase ratio (controlling the ratio of organic phase and inorganic phase), and the excessive water phase is automatically pumped to the waste alkali evaporating system.

In some embodiments, as shown in fig. 1, the first separator 2 and the second separator 3 respectively have a liquid inlet, an oil phase outlet and a water phase outlet, and the liquid inlets of the first separator 2 and the second separator 3 are connected to the oil phase outlet of the first-stage separation device 1 through a first oil phase pipeline 6, so that the oil phase separated by the first-stage separation device 1 enters the first separator 2 and the second separator 3 respectively in two paths; the oil phase outlet of the first separator 2 is communicated with the liquid inlet of the third separator 4 through a second oil phase pipeline 9, so that the oil phase separated from the first separator 2 enters the third separator 4 to continuously separate the water phase from the oil phase; an oil phase outlet of the second separator 3 is communicated with a liquid inlet of the fourth separator 5 through a third oil phase pipeline 10, so that the oil phase separated by the second separator 3 enters the fourth separator 5 to continuously separate the water phase from the oil phase; the water phase outlet of the first separator 2 and the water phase outlet of the second separator 3 are respectively connected to the decomposition reaction kettle, the waste alkali evaporation system and the first oil phase pipeline 6, wherein the first oil phase pipeline 6 is a pipeline for connecting the first-stage separation device 1 and the second-stage separation device in series so as to circularly separate the water phase, further separate the oil phase contained in the water phase and improve the separation efficiency. That is, the pipeline connected with the water phase outlet of the first separator 2 is divided into three paths, one path is connected with the decomposition reaction kettle through a third water phase pipeline 11, the other path is connected with the waste alkali evaporation system through a fourth water phase pipeline 12, and the other path is connected with the first oil phase pipeline 6 through a fifth water phase pipeline 13; the pipeline connected with the water phase outlet of the second separator 3 is also divided into three paths, one path is connected with the decomposition reaction kettle through a sixth water phase pipeline 14, the other path is connected with the waste alkali evaporation system through a seventh water phase pipeline 15, and the other path is connected with the first oil phase pipeline 6 through an eighth water phase pipeline 16. It should be noted that: the separator is equipped with remote and on-site level meter, when the level rises, the water phase is firstly returned to the decomposing kettle to provide phase ratio (controlling the ratio of organic phase and inorganic phase), and the excessive water phase is automatically pumped to the waste alkali evaporating system. The oil phase enters a first oil phase pipeline when the device is fed for circulation, firstly, organic phase circulation is established, then inorganic phase circulation is established, and excessive inorganic phase enters the waste alkali for evaporation under self pressure.

In some embodiments, the third separator 4 and the fourth separator 5 respectively have an oil phase outlet and a water phase outlet, and the oil phase outlet of the third separator 4 and the oil phase outlet of the fourth separator 5 are both connected to the alkane tower, so that the separated oil phase with higher purity can be subjected to subsequent processes; the water phase outlet of the third separator 4 and the water phase outlet of the fourth separator 5 are respectively connected to the waste alkali evaporation system and a pipeline for connecting the first-stage separation device 1 and the second-stage separation device in series, so that the water phase is circularly separated by the second-stage separation device, and the recovery amount of the oil phase is improved, specifically, referring to fig. 1, the pipeline connected with the water phase outlet of the third separator 4 is divided into two paths, one path is connected with the waste alkali evaporation system through a ninth water phase pipeline 17, and the other path is connected with the first oil phase pipeline 6 through a tenth water phase pipeline 18; the pipeline connected with the water phase outlet of the fourth separator 5 is also divided into two paths, one path is connected with the waste alkali evaporation system through an eleventh water phase pipeline 19, and the other path is connected with the first oil phase pipeline 6 through a twelfth water phase pipeline 20.

It should be noted that: the specific structure of the first separator 2, the second separator 3, the third separator 4 and the fourth separator 5, which are used as the separator of the first-stage separation device 1 and the second-stage separation device, is not limited as long as the separation of the water phase and the oil phase can be achieved, the present embodiment shows a horizontal separator, and the tank body of the separator is internally provided with a filler, and the form of the filler can be selected according to actual needs, for example, one or a combination of a plurality of coalescing fillers, inclined plate fillers, corrugated plate fillers and the like is adopted.

In order to facilitate recycling of the part of the aqueous phase separated by the third separator 4 and the fourth separator 5 back to the line connecting the primary separation device 1 and the secondary separation device in series, i.e., the first oil phase pipeline 6, as shown in fig. 1, the liquid-liquid separation system of the embodiment of the present invention further includes a first-stage water washing pump 21, the first-stage water washing pump 21 is disposed on a first circulation pipeline 23 where the tenth water phase pipeline 18 and the twelfth water phase pipeline 20 are merged, that is, one end of the first circulation pipeline 23 is connected to the water phase outlet of the third separator 4 and the water phase outlet of the fourth separator 5, the other end of the first circulation pipeline 23 is connected to a pipeline for connecting the first-stage separation device 1 and the second-stage separation device in series, so that part of the water phase separated by the third separator 4 and the fourth separator 5 can be smoothly circulated back into the first oil phase pipeline 6 and separated again by the second-stage separation device.

In some embodiments, the liquid-liquid separation system further includes a secondary water washing pump 22, the secondary water washing pump 22 is disposed on a second circulation pipeline 24 after the fifth aqueous phase pipeline 13 and the eighth aqueous phase pipeline 16 are merged, one end of the second circulation pipeline 24 is connected to the aqueous phase outlet of the first separator 2 and the aqueous phase outlet of the second separator 3, and the other end of the second circulation pipeline 24 is connected to a pipeline for connecting the primary separation device 1 and the secondary separation device in series. So that part of the water phase separated by the first separator 2 and the second separator 3 is smoothly sent to the first oil phase pipeline 6 through the secondary water washing pump 22, thereby facilitating the circular separation of the water phase by the secondary separation device and improving the separated oil phase quantity.

except for the case that the first separator 2 and the second separator 3, and the third separator 4 and the fourth separator 5 are provided with water washing pumps, the first-stage water washing pump 21 and the second-stage water washing pump 22 may be connected in series, so that the whole system forms a large circulation and the separation efficiency is improved, specifically, as shown in fig. 1, an inlet of the first-stage water washing pump 21 is connected to water phase outlets of the third separator 4 and the fourth separator 5, an outlet of the first-stage water washing pump 21 is connected to an inlet of the second-stage water washing pump 22, water phase outlets of the first separator 2 and the second separator 3 are connected to an inlet of the second-stage water washing pump 22, and an outlet of the second-stage water washing pump 22 is connected to a pipeline for connecting the first-stage separation device 1 and the second-stage separation device in series. In order to facilitate the water phase circulation separation of the whole system, the power of the secondary water washing pump 22 can be set to be larger than that of the primary water washing pump 21.

In some embodiments, with continued reference to fig. 1, the pipelines in series connection of the first separator 2 and the third separator 4, i.e. the second oil phase pipeline 9, and the pipelines in series connection of the second separator 3 and the fourth separator 5, i.e. the third oil phase pipeline 10, are respectively provided with water inlet pipelines 25 for increasing the content of water in the water phase separated in the first separator 2 and the second separator 3, so as to facilitate easier subsequent separation of the oil phase in the third separator 4 and the fourth separator 5, so as to improve the separation efficiency, and the water in the water inlet pipelines 25 may be process water, so as to reduce the cost, and of course, tap water may also be used.

Further, as shown in fig. 1, a first mixer 26 is arranged on a pipeline in which the first-stage separation device 1 and the second-stage separation device are connected in series, i.e., the first oil phase pipeline 6; a second mixer 27 is arranged on the second oil phase pipeline 9; a third mixer 28 is arranged on the third oil phase pipeline 10; a first mixer 26 is located downstream of the inlet 5 for the recycled aqueous phase connected to the first oil phase line 6 for thoroughly mixing the recycled aqueous phase separated by the first separator 2, the second separator 3, the third separator 4 and the fourth separator 5 with the oil phase from the primary separation device 1 to facilitate subsequent separation of the aqueous phase and the oil phase in the secondary separation device; a second mixer 27 is located downstream of the water inlet line 25 connected to the second oil phase line 9 for thoroughly mixing the water fed from the water inlet line 25 with the oil phase from the first separator 2 to facilitate oil-water separation thereof in the third separator 4, and likewise, a third mixer 28 is located downstream of the water inlet line 25 connected to the third oil phase line 10 for thoroughly mixing the water fed from the water inlet line 25 with the oil phase from the second separator 3 to facilitate oil-water separation thereof in the fourth separator 5, thereby improving separation efficiency.

The liquid-liquid separation system of the embodiment of the invention adopts a two-section series connection separation mode integrally, the latter section series connection comprises two-section parallel connection separation, each section parallel connection comprises two series connection separation respectively, three-stage separation is realized, the separation effect is improved, and the content of sodium ions in an oil phase (organic matter) is reduced from 30-50ppm to 0.5-1.0 ppm; the problem of alkali in cyclohexane in industrial production of cyclohexanone is solved, the fouling of the tubes of the reboiler of the alkane tower is prevented, the production period is prolonged, and the economic benefit is improved.

the embodiment of the invention also provides a liquid-liquid separation method, which comprises the following steps:

The liquid to be separated containing water phase and oil phase from the decomposition reaction kettle firstly enters a first-stage separation device 1 for primary separation, the water phase and the oil phase are separated, wherein one part of the water phase enters a waste alkali evaporation system, the other part of the water phase circulates back to the decomposition reaction kettle, and the oil phase enters a second-stage separation device connected with the first-stage separation device 1 in series for secondary separation;

The oil phase separated by the first-stage separation device 1 is divided into two paths and respectively enters a first separator 2 and a second separator 3 which are connected in parallel of the second-stage separation device;

The oil phase separated by the first separator 2 enters a third separator 4 connected in series with the first separator, and the oil phase separated by the second separator 3 enters a fourth separator 5 connected in series with the second separator; the water phase separated by the first separator 2 and the second separator 3 is divided into three parts, one part enters a waste alkali evaporation system for evaporation and recovery, the other part circulates back to the decomposition reaction kettle, enters the first-stage separation device 1 again for separation after the circulation reaction, and the other part circulates back to a pipeline for connecting the first-stage separation device 1 and the second-stage separation device in series, namely, circulates back to the first oil phase pipeline 6 to be divided into two paths again and then enters the first separator 2 and the second separator 3 respectively for separation;

The oil phase separated by the third separator 4 and the fourth separator 5 enters an alkane tower, the separated water phase is divided into two parts, one part enters a waste alkali evaporation system, and the other part is recycled and used for a pipeline connecting the first-stage separator 1 and the second-stage separator in series, so that the two parts are divided into two paths again and respectively enter the first separator 2 and the second separator 3 for separation.

The above description is intended to be illustrative and not restrictive. For example, the above-described examples (or one or more versions thereof) may be used in combination with each other, and it is contemplated that the embodiments may be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.