阅读说明：本技术 从永固紫离心母液中回收邻二氯苯的方法和装置 (Method and device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor ) 是由 王正贤 王彬彬 吴声 李泽荣 孙涛 宁亮 马飞 王聪 于 2020-08-27 设计创作，主要内容包括：本发明提供一种从永固紫离心母液中回收邻二氯苯的方法和装置,属于永固紫生产技术领域。方法包括减压蒸馏、水蒸气蒸馏及排渣步骤,采用水蒸气蒸馏法替代传统的高温熬渣法,一方面,将水蒸气通入蒸馏残渣中,形成水蒸气与邻二氯苯的共沸体系,故而在较低温度状态下,实现从蒸馏残渣中,进一步回收邻二氯苯,降低的设备损耗,延长了设备的使用寿命,且有效节约了能源,降低了生产成本。另一方面,部分水蒸气在体系内凝结成凝液,蒸馏残渣中的盐类溶解于凝液中,并与蒸馏残渣中不溶解的组分形成浆液,使得蒸馏残渣能够在低温下被顺利排出,降低了高温排渣的安全风险,降低了尾气处理压力,降低了环境风险。(The invention provides a method and a device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor, belonging to the technical field of permanent violet production. The method comprises the steps of reduced pressure distillation, steam distillation and slag discharge, and adopts the steam distillation method to replace the traditional high-temperature slag boiling method, on one hand, the steam is introduced into the distillation residues to form an azeotropic system of the steam and the o-dichlorobenzene, so that the o-dichlorobenzene is further recovered from the distillation residues at a lower temperature, the equipment loss is reduced, the service life of the equipment is prolonged, the energy is effectively saved, and the production cost is reduced. On the other hand, part of the steam is condensed into condensate in the system, the salt in the distillation residue is dissolved in the condensate and forms slurry with insoluble components in the distillation residue, so that the distillation residue can be smoothly discharged at low temperature, the safety risk of high-temperature slag discharge is reduced, the tail gas treatment pressure is reduced, and the environmental risk is reduced.)

1. A method for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor is characterized by comprising the following steps:

a. distilling under reduced pressure to extract o-dichlorobenzene and obtain distillation residue;

b. steam distillation, namely introducing steam into the distillation residue to perform steam distillation, extracting residual o-dichlorobenzene and simultaneously obtaining a residue-water mixture;

c. discharging slag, cooling the slag-water mixture, and discharging slag at low temperature.

2. The method for recovering ortho-dichlorobenzene from permanent violet centrifuge mother liquor according to claim 1, wherein in step b, the temperature of the vapor is 120-150 ℃.

3. The method for recovering ortho-dichlorobenzene from permanent violet centrifuge mother liquor as in claim 1, wherein in step c, the temperature of the slag-water mixture is reduced to below 70 ℃.

4. The device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor is characterized by comprising a distillation kettle, an o-dichlorobenzene recovery assembly and a slag discharging water tank, wherein a centrifugal mother liquor feeding pipe is arranged on the distillation kettle, a slag-water mixture discharging pipe is arranged at the kettle bottom of the distillation kettle, and the slag-water mixture discharging pipe is connected with the slag discharging water tank;

the ortho-dichlorobenzene recycling assembly comprises a recycling condenser and a first condensate receiving tank, the feeding end of the hot side of the recycling condenser is connected with the distillation kettle, the first condensate receiving tank is connected with the condensate discharging end of the recycling condenser, and the first condensate receiving tank is also connected with a negative pressure generating piece;

and the distillation kettle is also connected with a steam feeding pipe.

5. The apparatus for recovering ortho-dichlorobenzene from permanent violet centrifuge mother liquor according to claim 4, wherein said vapor feed pipe extends into the bottom of said distillation still.

6. The apparatus according to claim 5, wherein a vapor distribution coil is connected to the end of the vapor feed pipe located in the distillation still, and the vapor distribution coil is provided with a plurality of vapor distribution holes.

7. The apparatus for recovering o-dichlorobenzene from permanent violet centrifuge mother liquor according to claim 4, wherein a heating jacket is arranged on the outer side of the distillation still, and a conduction oil feeding pipe and a conduction oil discharging pipe are connected to the heating jacket.

8. The apparatus for recovering ortho-dichlorobenzene from permanent violet centrifuge mother liquor according to claim 4, wherein the ortho-dichlorobenzene recovery module further comprises a second condensate receiving tank, and the second condensate receiving tank is provided with an oil-water separation tank.

9. The apparatus for recovering ortho-dichlorobenzene from permanent violet centrifuge mother liquor according to claim 4, wherein the residue discharge water tank is provided with an exhaust gas collecting pipe.

Technical Field

The invention belongs to the technical field of permanent violet production, and particularly relates to a method and a device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor.

Background

The permanent violet RL is a high-grade organic pigment of dioxazine class, has outstanding tinting strength and brightness, excellent heat resistance and penetration resistance and good light fastness, has wide application range, and is popular in the fields of paint, plastics, organic glass, rubber, textile printing, solvent ink, water-based ink, packaging printing and the like.

The permanent violet RL is produced by the following main processes: dissolving carbazole in alkali solution for alkylation to obtain N-ethyl carbazole, nitrating N-ethyl carbazole in nitric acid, and then H₂Reducing, condensing in tetrachlorobenzoquinone, ring-closing in benzene sulfonyl chloride, oxidizing to obtain crude permanent violet liquid, filtering, drying, crushing and other steps. Filtering (or centrifuging) the crude permanent violet solution to obtain filtrate (or centrifuging mother liquor) containing a large amount of o-dichlorobenzene as solvent, wherein the chlorobenzene is required to be recycled

Traditionally, the method for recovering the o-dichlorobenzene in the centrifugal mother liquor by adopting a negative pressure distillation mode is divided into two stages, wherein the first stage is a low-temperature distillation stage, most of the o-dichlorobenzene is distilled out of the centrifugal mother liquor, and residues at the bottom of a distillation kettle mainly contain permanent violet, triethylamine benzenesulfonate, tetrachlorobenzoquinone and o-dichlorobenzene components. The second stage is a high-temperature slag boiling stage, namely, the temperature of the system is increased to more than 250 ℃, so that the slag is in a molten state, and the o-dichlorobenzene is evaporated. Although the method for recovering o-dichlorobenzene from the centrifugal mother liquor can recover o-dichlorobenzene, the method has the following problems in the residue boiling stage:

firstly, the equipment for recycling the o-dichlorobenzene is a glass lined kettle, and the distillation kettle is seriously worn and short in service life due to long-time slag boiling operation at the high temperature of 250 ℃;

secondly, the slag is discharged at high temperature in a molten state, so that high safety risk exists, and the high-temperature slag is discharged into a cooling water pool to generate a large amount of waste gas, so that the requirement on a waste gas absorption treatment system is high, and the risk of environmental pollution is high;

thirdly, the high temperature slag melting process needs higher heat, which causes energy waste and increases the cost.

Disclosure of Invention

In view of the above, the invention provides a method for recovering o-dichlorobenzene from permanent violet centrifugation mother liquor, so as to solve the technical problems of large equipment loss, high safety risk and high energy cost caused by high-temperature slag boiling in the prior art.

The invention also provides a device for recovering o-dichlorobenzene from the permanent violet centrifugal mother liquor, so as to reduce equipment loss, reduce safety risk and reduce production cost.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a method for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor comprises the following steps:

a. distilling under reduced pressure to extract o-dichlorobenzene and obtain distillation residue;

b. steam distillation, namely introducing steam into the distillation residue to perform steam distillation, extracting residual o-dichlorobenzene and simultaneously obtaining a residue-water mixture;

c. discharging slag, cooling the slag-water mixture, and discharging slag at low temperature.

Preferably, in step b, the temperature of the vapor is 120 ℃ to 150 ℃.

Preferably, in step c, the temperature of the slag-water mixture is reduced to below 70 ℃.

A device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor comprises a distillation kettle, an o-dichlorobenzene recovery assembly and a slag discharge water tank, wherein a centrifugal mother liquor feeding pipe is arranged on the distillation kettle, a slag-water mixture discharge pipe is arranged at the kettle bottom of the distillation kettle, and the slag-water mixture discharge pipe is connected with the slag discharge water tank; the ortho-dichlorobenzene recycling assembly comprises a recycling condenser and a first condensate receiving tank, the feeding end of the hot side of the recycling condenser is connected with the distillation kettle, the first condensate receiving tank is connected with the condensate discharging end of the recycling condenser, and the first condensate receiving tank is also connected with a negative pressure generating piece; and the distillation kettle is also connected with a steam feeding pipe.

Preferably, the vapor feed pipe extends into the bottom of the still.

Preferably, one end of the steam feed pipe, which is positioned in the distillation still, is connected with a steam distribution coil pipe, and a plurality of steam distribution holes are formed in the steam distribution coil pipe.

Preferably, a heating jacket is arranged on the outer side of the distillation kettle, and a heat conduction oil feeding pipe and a heat conduction oil discharging pipe are connected to the heating jacket.

Preferably, the ortho-dichlorobenzene recycling assembly further comprises a second condensate receiving tank, and an oil-water separation tank is arranged on the second condensate receiving tank.

Preferably, the slag discharging water tank is provided with a tail gas collecting pipe.

According to the technical scheme, the invention provides a method and a device for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor, and the method and the device have the beneficial effects that: in the process of recovering o-dichlorobenzene from permanent violet centrifugal mother liquor, a steam distillation method is adopted to replace the traditional high-temperature residue boiling method, and the method has the following advantages in several aspects: firstly, steam is introduced into distillation residues to form an azeotropic system of the steam and the o-dichlorobenzene, so that the o-dichlorobenzene can be further recovered from the distillation residues at a lower temperature (the system temperature is less than 100 ℃). Meanwhile, the equipment loss is greatly reduced due to the lower system temperature, the service life of the equipment is prolonged, the energy is effectively saved, and the production cost is reduced. And secondly, partial steam is condensed into condensate in the system, salts (such as triethylamine benzenesulfonate) in the distillation residues are dissolved in the condensate and form slurry with insoluble components (such as permanent violet) in the distillation residues, so that the distillation residues can be smoothly discharged at low temperature, the safety risk of high-temperature slag discharge is reduced, and meanwhile, a large amount of diffused gas cannot be generated after the low-temperature slag-water mixture is contacted with cooling water, so that the tail gas treatment pressure is reduced, and the environmental risk is reduced.

Drawings

FIG. 1 is a process flow diagram of a method for recovering ortho-dichlorobenzene from permanent violet centrifugation mother liquor.

FIG. 2 is a line flow diagram of an apparatus for recovering ortho-dichlorobenzene from permanent violet centrifugation mother liquor.

In the figure: the device for recovering ortho-dichlorobenzene from permanent violet centrifugal mother liquor comprises a device 10 for recovering ortho-dichlorobenzene from permanent violet centrifugal mother liquor, a distillation still 100, a centrifugal mother liquor feeding pipe 110, a slag-water mixture discharging pipe 120, a steam feeding pipe 130, a steam distribution coil pipe 131, a heating jacket 140, a heat conduction oil feeding pipe 141, a heat conduction oil discharging pipe 142, an ortho-dichlorobenzene recovering assembly 200, a recovering condenser 210, a first condensate receiving groove 220, a negative pressure generating piece 221, a second condensate receiving groove 230, an oil-water separation groove 231, a slag discharging water tank 300 and a tail gas collecting pipe 310.

Detailed Description

The technical scheme and the technical effect of the invention are further elaborated in the following by combining the drawings of the invention.

Referring to fig. 1, in an embodiment, a method for recovering ortho-dichlorobenzene from permanent violet centrifugation mother liquor, comprises the following steps:

s10 distillation under reduced pressure is carried out to extract o-dichlorobenzene and obtain distillation residue at the same time.

And (3) feeding the permanent violet centrifugal mother liquor into a reduced pressure distillation kettle, controlling the vacuum degree of the distillation kettle to be 40 KPaA-60 KPaA (KPaA represents absolute pressure unit), and controlling the kettle temperature of the distillation kettle to be 80-100 ℃ for reduced pressure distillation. The o-dichlorobenzene component in the permanent violet centrifugal mother liquor is evaporated, extracted from a distillation still and recycled. Other components (mainly comprising about 35 percent of permanent violet, about 25 percent of benzenesulfonic acid triethylamine salt and about 20 percent of chloranil) in the permanent violet centrifugal mother liquor are gradually separated out at the bottom of the distillation kettle. When most of the o-dichlorobenzene was distilled out of the system, the remaining components were present in the still pot as distillation residue.

S20, steam distillation, namely introducing steam into the distillation residue to perform steam distillation, extracting residual o-dichlorobenzene, and simultaneously obtaining a residue-water mixture.

Steam is introduced into the distillation residue under normal pressure or slightly negative pressure, preferably, steam with a temperature of 120 to 150 ℃ (i.e., steam with a pressure of 0.2 to 0.5 MPa) is introduced into the distillation residue. On one hand, the introduction of the steam forms an azeotropic system of the steam and the o-dichlorobenzene, so that the o-dichlorobenzene can be further recovered from the distillation residue at a lower temperature (the system temperature is less than 100 ℃). Meanwhile, the recovery efficiency of the o-dichlorobenzene is improved by using steam stripping, and experimental detection data show that the o-dichlorobenzene in the system can be fully recovered by using a steam distillation method, and the recovery rate reaches more than 97%. Meanwhile, steam is condensed in the distillation kettle to form condensate, after the permanent violet centrifugal mother liquor is subjected to reduced pressure distillation, salts (such as triethylamine benzenesulfonate) contained in distillation residues are dissolved in the condensate and form slurry with insoluble components (such as permanent violet) in the distillation residues, so that the distillation residues can be smoothly discharged at low temperature, the safety risk of high-temperature slag discharge is reduced, and meanwhile, after a low-temperature slag-water mixture is contacted with cooling water, a large amount of diffused gas cannot be generated, so that the tail gas treatment pressure is reduced, and the environmental risk is reduced.

And S30, discharging slag, cooling the slag-water mixture, and discharging slag at low temperature.

After the steam distillation is finished, the system is naturally cooled or actively cooled by using a cooling medium, for example, after the temperature of the slag-water mixture is reduced to below 70 ℃, slag begins to be discharged into a cooling water tank (or a slag tank). Because in the stills, distillation residue and steam condensate water intensive mixing form the slag-water mixture of emulsion form for distillation residue can be discharged smoothly at low temperature, has reduced the safe risk of high temperature row sediment, and simultaneously, microthermal slag-water mixture can not produce a large amount of diffused gas with the cooling water back of contacting, thereby has reduced tail gas treatment pressure, has reduced the environmental risk.

Referring to fig. 2, in another embodiment, an apparatus 10 for recovering ortho-dichlorobenzene from permanent violet centrifugal mother liquor adopts reduced pressure distillation and steam distillation to recover ortho-dichlorobenzene from permanent violet centrifugal mother liquor. The device 10 for recovering o-dichlorobenzene from permanent violet centrifugal mother liquor comprises a distillation kettle 100, an o-dichlorobenzene recovery assembly 200 and a slag discharge water tank 300, wherein the distillation kettle 100 is provided with a centrifugal mother liquor feeding pipe 110, the kettle bottom of the distillation kettle 100 is provided with a slag-water mixture discharge pipe 120, and the slag-water mixture discharge pipe 120 is connected with the slag discharge water tank 300. Ortho-dichlorobenzene retrieves subassembly 200 receives groove 220 including retrieving condenser 210 and first lime set, the hot side feed end of retrieving condenser 210 is connected stills 100, first lime set receives groove 220 to be connected retrieve condenser 210's lime set discharge end, first lime set receives still to be connected with negative pressure generator 221 on the groove. The still 100 is also connected to a vapor feed line 130.

The permanent violet centrifugal mother liquor is conveyed into the distillation still 100 through the centrifugal mother liquor feeding pipe 110, and is firstly subjected to reduced pressure distillation. Controlling the vacuum degree of the distillation kettle to be 40 KPaA-60 KPaA (KPaA represents absolute pressure unit), and the temperature of the distillation kettle to be 80-100 ℃ to carry out reduced pressure distillation. And (3) evaporating the ortho-dichlorobenzene component in the permanent violet centrifugal mother liquor, condensing an evaporated gas phase by using the recovery condenser 210, collecting the ortho-dichlorobenzene with the mass concentration of 70-80% in the condensate into the first condensate receiving tank 220, and recycling the ortho-dichlorobenzene component. Other components (mainly comprising about 35% of the permanent violet, about 25% of the triethylamine benzenesulfonate and about 20% of chloranil) in the permanent violet centrifugal mother liquor are gradually separated out at the bottom of the distillation kettle 100. When most of the o-dichlorobenzene was distilled out of the system, the remaining components were present in the distillation still 100 in the form of distillation residue.

After the reduced pressure distillation is finished, the distillation residue mainly contains permanent violet, benzene sulfonic acid triethylamine salt, tetrachlorobenzoquinone and a small amount of o-dichlorobenzene components, and steam with the temperature of 120-150 ℃ (namely steam with the pressure of 0.2-0.5 MPa) is introduced into the steam inlet pipe 130 through the steam inlet pipe 130 for steam distillation. In the distillation process, an azeotropic system of steam and o-dichlorobenzene is formed, the steam is assisted to be stripped by steam, the steam carrying the o-dichlorobenzene steam is discharged from the gas phase of the distillation kettle 100 and condensed by the recovery condenser 210, condensate mainly comprises water and o-dichlorobenzene and is collected in the first condensate receiving tank 220, and the o-dichlorobenzene is recycled after oil-water separation. Meanwhile, steam is condensed, salts (such as triethylamine benzenesulfonate) contained in distillation residues are dissolved in condensate and form slurry with insoluble components (such as permanent violet) in the distillation residues, so that the distillation residues can be smoothly discharged from the residue-water mixture discharge pipe 120 at a low temperature, the safety risk of high-temperature slag discharge is reduced, and simultaneously, a large amount of diffused gas cannot be generated after the low-temperature residue-water mixture is contacted with cooling water, so that the tail gas treatment pressure is reduced, and the environmental risk is reduced.

In one embodiment, the vapor feed line 130 extends into the bottom of the still 100 to allow for sufficient aeration. Further, for increasing the steam aeration area and improving the steam distillation efficiency and the gas stripping efficiency, the steam feed pipe 130 is located one end in the distillation still 100 is connected with a steam distribution coil pipe 131, and a plurality of steam distribution holes are formed in the steam distribution coil pipe 131. High pressure steam enters the vapor distribution coil 131 from the vapor feed pipe 130 and is diffused out of the vapor distribution holes to fully contact the distillation residue.

In a specific embodiment, a heating jacket 140 is disposed outside the distillation still 100, and a heat conduction oil feeding pipe 141 and a heat conduction oil discharging pipe 142 are connected to the heating jacket 140, so as to provide a heat source for the distillation still 100 by using heat conduction oil.

In another embodiment, the ortho-dichlorobenzene recycling assembly 200 further comprises a second condensate receiving tank 230, the second condensate receiving tank 230 is connected with the condensate outlet of the recycling condenser 210, and an oil-water separation tank 231 is arranged on the second condensate receiving tank 230. The second condensate collecting tank 230 is used for collecting vapor gas, and the gas phase condensate of the distillation still 100 is obtained, and simultaneously oil-water separation is realized, and ortho-dichlorobenzene is recovered.

In one embodiment, the slag discharging water tank 300 is provided with an exhaust gas collecting pipe 310 for collecting the off-flavor gas generated in the slag discharging water tank 300.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.