阅读说明：本技术 一种煤焦油提酚及含酚水处理的耦合装置及耦合工艺 (Coupling device and coupling process for coal tar phenol extraction and phenol-containing water treatment ) 是由 王庆元 严朕 潘越 侯向楠 黄云 于 2021-10-18 设计创作，主要内容包括：本发明提供了一种煤焦油提酚及含酚水处理的耦合装置及耦合工艺,所述耦合装置通过多个分馏工段与2级萃取工段的设计结合,再辅以水洗工段以及低温分离工段,同时解决了煤焦油提酚以及焦油蒸馏过程中的环保问题；所述耦合工艺通过萃取精馏和液液萃取相结合的工艺,提高了粗酚产品的品质,降低了杂质中性油的含量,并且还通过低温预分离粗酚溶液的操作,大幅度降低了粗酚精馏脱水工段的能耗,具有较好的工业应用前景。(The invention provides a coupling device and a coupling process for treating coal tar phenol extraction and phenol-containing water, wherein the coupling device is combined with a 2-stage extraction section through the design of a plurality of fractionation sections, and is assisted by a water washing section and a low-temperature separation section, so that the environmental protection problem in the coal tar phenol extraction and tar distillation process is solved; the coupling process improves the quality of crude phenol products and reduces the content of impurity neutral oil by a process combining extractive distillation and liquid-liquid extraction, and greatly reduces the energy consumption of a crude phenol rectification dehydration working section by the operation of pre-separating a crude phenol solution at low temperature, thereby having better industrial application prospect.)

1. A coupling device for coal tar phenol extraction and phenol-containing water treatment is characterized by comprising a coal tar fractionation unit, a first extraction unit, a second extraction unit, a light oil recovery unit, a first extractant recovery unit, a water washing unit, a dephenolized oil fractionation unit, a separation unit and a crude phenol dehydration unit;

the coal tar fractionation unit is connected with an extract liquid inlet of the first extraction unit;

an extract phase outlet of the first extraction unit is connected with an extract liquid inlet of the second extraction unit; a raffinate phase outlet of the first extraction unit is connected with the water washing unit; the water washing unit is connected with the dephenolized oil fractionation unit;

an extract phase outlet of the second extraction unit is connected with the light oil recovery unit; a raffinate phase outlet of the second extraction unit is connected with the first extractant recovery unit;

a heavy component outlet of the light oil recovery unit is connected with the dephenolized oil fractionation unit;

a heavy component outlet of the first extractant recovery unit is connected with the separation unit; the separation unit is connected with the crude phenol dehydration unit;

a light component outlet of the dephenolized oil fractionating unit is connected with a first side line inlet of the coal tar fractionating unit; and a heavy component outlet of the dephenolized oil fractionating unit is connected with a second side inlet of the coal tar fractionating unit.

2. The coupling device of claim 1, wherein the coal tar fractionation unit comprises a packed rectification column;

preferably, the packed rectifying tower at least comprises 4 packing sections, and the packing section close to the top is defined as a first packing section;

preferably, a coal tar inlet is arranged at the bottom end of the side wall of the packing rectification tower;

preferably, the top end of the packed rectifying tower is provided with a first light component outlet;

preferably, a first side line inlet is arranged between the first packing section and the second packing section of the packing rectification column;

preferably, a side draw outlet is arranged between the third packing section and the fourth packing section of the packing rectification tower;

preferably, a second side draw inlet is provided between the first side draw inlet and the side draw outlet;

preferably, the first light component outlet and the side draw outlet are both connected with an extract inlet of the first extraction unit.

3. The coupling device according to claim 1 or 2, wherein the first extraction unit comprises a first extraction column;

preferably, an extract liquid inlet is formed at the top end of the side wall of the first extraction tower;

preferably, the bottom end of the side wall of the first extraction tower is provided with a first extractant inlet;

preferably, the second extraction unit comprises a second extraction column;

preferably, an extract liquid inlet is formed at the top end of the side wall of the second extraction tower;

preferably, the bottom end of the side wall of the second extraction tower is provided with a second extractant inlet.

4. The coupling device according to any one of claims 1 to 3, wherein the light oil recovery unit comprises a first rectification column;

preferably, the light component outlet of the light oil recovery unit is connected to the second extractant inlet;

preferably, the first extractant recovery unit comprises a second rectification column;

preferably, the light fraction outlet of the first extractant recovery unit is connected to the first extractant inlet.

5. The coupling device according to any one of claims 1-3, wherein the water wash unit comprises a water wash tower;

preferably, a washing water inlet is formed at the top end of the side wall of the water washing tower;

preferably, the bottom end of the side wall of the water washing tower is provided with an inlet for water to be washed;

preferably, the water washing unit is further connected to the first extractant inlet;

preferably, the dephenolized oil fractionation unit comprises a third rectification column.

6. The coupling device according to any one of claims 1-5, wherein the separation unit comprises a separation tank;

preferably, the separation unit is also connected with the first extractant inlet and the water washing unit respectively and independently;

preferably, the crude phenol dehydration unit comprises a fourth rectification column;

preferably, the light component outlet of the crude phenol dehydration unit is also independently connected with the first extractant inlet and the water washing unit respectively.

7. A coupling process for extracting phenol from coal tar and treating phenol-containing water, which is characterized in that the coupling process is carried out by using the coupling device of any one of claims 1 to 6, and the coupling process comprises the following steps:

(1) performing extraction rectification on the coal tar to obtain phenol-containing oil;

(2) performing primary extraction on the phenol-containing oil obtained in the step (1) by using a first extracting agent, and performing secondary extraction on the obtained primary extract phase by using a second extracting agent to obtain a secondary extract phase and a secondary raffinate phase;

washing the obtained first-stage raffinate phase with water to obtain a first extracting agent and dephenolized oil;

(3) performing first rectification on the secondary extract phase obtained in the step (2) to obtain a second extractant and neutral oil; performing second rectification on the secondary raffinate phase obtained in the step (2) to obtain a first extracting agent and a crude phenol solution;

mixing the neutral oil with the dephenolized oil obtained in the step (2) and then dividing the mixture into two parts, wherein one part is used for obtaining a dephenolized oil product; performing third rectification on the other part of the distillate to obtain dephenolized light oil and dephenolized heavy oil, wherein the dephenolized light oil and the dephenolized heavy oil are respectively and independently returned to the step (1) for utilization;

and (4) sequentially carrying out low-temperature separation and fourth rectification on the crude phenol solution to obtain a crude phenol product.

8. The coupling process of claim 7, wherein the primary extractant of step (2) comprises an aqueous alcohol solution;

preferably, the alcohol aqueous solution comprises any one of methanol aqueous solution, ethanol aqueous solution or propanol aqueous solution;

preferably, the mass ratio of the primary extractant to the phenolic oil is (0.2-2) to 1;

preferably, the temperature of the primary extraction in the step (2) is 20-60 ℃;

preferably, the pressure of the primary extraction in the step (2) is 100-800 kPa.

9. The coupling process of claim 7 or 8, wherein the secondary extractant of step (2) comprises an alkane solvent;

preferably, the alkane solvent comprises hydrogenated light gasoline or cyclohexane;

preferably, the mass ratio of the second extractant to the primary extractant phase is (0.2-2): 1;

preferably, the temperature of the secondary extraction in the step (2) is 20-60 ℃;

preferably, the pressure of the secondary extraction in the step (2) is 100-800 kPa.

10. The coupling process according to any one of claims 7 to 9, wherein the temperature of the water washing in step (2) is 20 to 60 ℃;

preferably, the pressure of the water washing in the step (2) is 100-800 kPa;

preferably, the first extractant obtained after the water washing in the step (2) is returned for recycling.

Technical Field

The invention belongs to the technical field of coal tar production, and relates to a coupling device and a coupling process for extracting phenol from coal tar and treating phenol-containing water.

Background

The medium-low temperature coal tar is used as an important raw material in the field of coal chemical industry, and has the characteristics of high phenol content and high water content. Therefore, in the process of producing fuel oil by hydrogenation of coal tar, due to the existence of the phenolic compound, not only is the hydrogen consumption high, but also the yield of the product is reduced due to the water generated by hydrodeoxygenation; however, due to the high added value of the phenolic compounds, if the phenol in the coal tar can be separated, the economy of the hydrogenation process can be inevitably improved.

At present, various coal tar phenol extraction processes mainly comprise an acid-base method and a solvent selection method; in industrial production, an acid-base phenol extraction process is mainly adopted, but the process generates a large amount of acid-base-containing wastes which are corrosive and have great harm to the environment, so the acid-base phenol extraction process is gradually limited by environmental regulations; the selective solvent method leads to the inclusion of neutral oil with higher impurity content in the extraction phase due to the poor selectivity of the used extractant, thus causing the quality reduction of crude phenol products.

In addition, in the distillation process of the coal tar, a large amount of phenol-containing sewage is generated due to the fact that raw materials carry water and steam is injected (steamed) at the bottom of a tower, the phenol-containing sewage is required to be subjected to dephenolizing treatment before biochemical treatment at present, common methods include an ether and ketone extraction process, a steam dephenolizing method, a chemical precipitation method and the like, but the problems of long treatment process flow, high energy consumption and high treatment cost exist. In the prior art, partial coal tar processing products are returned to reduce the phenol content in phenol-containing sewage in the coal tar distillation process, but the overall energy consumption is increased, and the yield of the processed products is reduced.

CN102219649A discloses a method for extracting phenolic compounds from coal liquefied oil or coal tar, which comprises 1) distilling coal liquefied oil or coal tar, and cutting the fraction at <260 ℃; 2) mixing an extracting agent with the phenol oil fraction section and then layering; 3) separating and collecting the extractant layer containing phenolic compounds; 4) performing multi-stage back extraction on the phenolic compound in the extractant layer to obtain a back extractant-phenolic solution and an extractant; 5) separating the stripping agent-phenol solution by rectification, recovering the stripping agent, recycling, and separating to obtain crude phenol; 6) removing neutral oil carried in the phenolic compounds by steam stripping to finally obtain a crude phenol product.

CN108484368A discloses a method for extracting phenolic compounds from coal tar by using ethanolamine, which comprises the following specific steps: (1) distilling coal tar or coal liquefaction oil, and cutting fractions at the temperature of 170-230 ℃; (2) mixing an extracting agent with the phenol oil fraction section and then layering; (3) separating and collecting the lower phenolic oil layer containing phenolic compounds; (4) performing multi-stage extraction on the upper layer of the phenol oil, and mixing the extracted phenol oil layer with the lower layer of the phenol oil; (5) and (3) separating the extractant-phenol solution by rectification, recovering the extractant, recycling, and separating to obtain crude phenol.

When the method is used for extracting phenol, multistage extraction is needed, the equipment cost is high, a large amount of phenol-containing sewage is generated in the distillation process, the treatment is difficult, the subsequent treatment cost is high, and the quality of the obtained crude phenol product is poor.

In summary, aiming at solving the environmental protection problem caused by phenol-containing water generated in the distillation process of coal tar phenol extraction and tar, how to provide a coupling process for coal tar phenol extraction and phenol-containing water treatment is a problem to be solved urgently at present, which reduces the phenol content in the sewage of coal tar in the distillation process and improves the quality of crude phenol products.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a coupling device and a coupling process for treating coal tar phenol extraction and phenol-containing water, wherein the coupling device simultaneously solves the environmental protection problems in the coal tar phenol extraction and coal tar distillation process through an optimized treatment route; the coupling process improves the quality of crude phenol products and reduces the content of impurity neutral oil through extractive distillation and liquid-liquid extraction processes, and has good industrial application prospect.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a coupling device for coal tar phenol extraction and phenol-containing water treatment, which comprises a coal tar fractionation unit, a first extraction unit, a second extraction unit, a light oil recovery unit, a first extractant recovery unit, a water washing unit, a dephenolized oil fractionation unit, a separation unit and a crude phenol dehydration unit;

the coal tar fractionation unit is connected with an extract liquid inlet of the first extraction unit;

an extract phase outlet of the first extraction unit is connected with an extract liquid inlet of the second extraction unit; a raffinate phase outlet of the first extraction unit is connected with the water washing unit; the water washing unit is connected with the dephenolized oil fractionation unit;

an extract phase outlet of the second extraction unit is connected with the light oil recovery unit; a raffinate phase outlet of the second extraction unit is connected with the first extractant recovery unit;

a heavy component outlet of the light oil recovery unit is connected with the dephenolized oil fractionation unit;

a heavy component outlet of the first extractant recovery unit is connected with the separation unit; the separation unit is connected with the crude phenol dehydration unit;

a light component outlet of the dephenolized oil fractionating unit is connected with a first side line inlet of the coal tar fractionating unit; and a heavy component outlet of the dephenolized oil fractionating unit is connected with a second side inlet of the coal tar fractionating unit.

In the invention, the coupling device solves the environmental protection problem in the processes of extracting phenol from coal tar and distilling tar by combining the design of a plurality of fractionation sections and 2-stage extraction sections and assisting a water washing section and a low-temperature separation section, greatly reduces the energy consumption and is beneficial to industrial application.

In the present invention, the recovery of light oil refers to the recovery of "neutral oil".

The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.

As a preferable technical scheme of the invention, the coal tar fractionating unit comprises a filler rectifying tower.

Preferably, the packed rectification column comprises at least 4 packing sections, such as 4, 5, 6, 7, 8 or 9, etc., but not limited to the recited values, and other values not recited in this range of values are equally applicable, and the packing section near the top is defined as the first packing section.

Preferably, a coal tar inlet is arranged at the bottom end of the side wall of the packing rectification tower.

Preferably, the top end of the packed rectification column is provided with a first light component outlet.

Preferably, a first side inlet is arranged between the first packing section and the second packing section of the packing rectification column.

Preferably, a side draw outlet is arranged between the third packing section and the fourth packing section of the packing rectification column.

Preferably, a second side entry port is provided between the first side entry port and the side take-off port.

Preferably, the first light component outlet and the side draw outlet are both connected with an extract inlet of the first extraction unit.

Hereinafter, as a preferred embodiment of the present invention, the first extraction unit includes a first extraction column.

Preferably, the top end of the side wall of the first extraction tower is provided with an extract liquid inlet.

Preferably, the bottom end of the side wall of the first extraction tower is provided with a first extractant inlet.

Preferably, the second extraction unit comprises a second extraction column.

Preferably, the top end of the side wall of the second extraction tower is provided with an extract liquid inlet.

Preferably, the bottom end of the side wall of the second extraction tower is provided with a second extractant inlet.

Hereinafter, as a preferable embodiment of the present invention, the light oil recovery unit includes a first rectifying tower.

Preferably, the light component outlet of the light oil recovery unit is connected to the second extractant inlet.

Preferably, the first extractant recovery unit comprises a second rectification column.

Preferably, the light fraction outlet of the first extractant recovery unit is connected to the first extractant inlet.

In the following, as a preferred embodiment of the present invention, the water washing unit includes a water washing tower.

Preferably, the top end of the side wall of the water washing tower is provided with a washing water inlet.

Preferably, the bottom end of the side wall of the water washing tower is provided with an inlet for water to be washed.

Preferably, the water wash unit is further connected to the first extractant inlet.

Preferably, the dephenolized oil fractionation unit comprises a third rectification column.

In the following, as a preferred embodiment of the present invention, the separation unit comprises a separation tank.

Preferably, the separation unit is further independently connected to the first extractant inlet and the water washing unit, respectively. Preferably, the crude phenol dehydration unit comprises a fourth rectification column.

Preferably, the light component outlet of the crude phenol dehydration unit is also independently connected with the first extractant inlet and the water washing unit respectively.

In a second aspect, the invention provides a coupling process for phenol extraction from coal tar and phenol-containing water treatment, wherein the coupling process is carried out by using the coupling device of the first aspect, and comprises the following steps:

(1) performing extraction rectification on the coal tar to obtain phenol-containing oil;

(2) performing primary extraction on the phenol-containing oil obtained in the step (1) by using a first extracting agent, and performing secondary extraction on the obtained primary extract phase by using a second extracting agent to obtain a secondary extract phase and a secondary raffinate phase;

washing the obtained first-stage raffinate phase with water to obtain a first extracting agent and dephenolized oil;

(3) performing first rectification on the secondary extract phase obtained in the step (2) to obtain a second extractant and neutral oil; performing second rectification on the secondary raffinate phase obtained in the step (2) to obtain a first extracting agent and a crude phenol solution;

mixing the neutral oil with the dephenolized oil obtained in the step (2) and then dividing the mixture into two parts, wherein one part is used for obtaining a dephenolized oil product; performing third rectification on the other part of the distillate to obtain dephenolized light oil and dephenolized heavy oil, wherein the dephenolized light oil and the dephenolized heavy oil are respectively and independently returned to the step (1) for utilization;

and (4) sequentially carrying out low-temperature separation and fourth rectification on the crude phenol solution to obtain a crude phenol product.

In the invention, the first rectification, the second rectification, the third rectification and the fourth rectification do not refer to the rectification sequence, do not imply the relation of gradual progression, and only play a distinguishing role.

In the invention, the coupling process adopts extractive distillation and liquid-liquid extraction processes, so that the phenol content of the phenol-containing sewage is reduced while the phenol substances in the coal tar are extracted; furthermore, a two-stage extraction process is adopted, so that the quality of a crude phenol product is improved, and the content of impurities (neutral oil) is reduced; in addition, the characteristic that the solubility of the phenolic compound in water is reduced along with the reduction of temperature is utilized, low-temperature separation dehydration is firstly carried out, and then rectification dehydration is carried out, so that the dehydration energy consumption is greatly reduced, and the resource utilization is realized.

In the invention, if the conventional rectification process and the liquid-liquid extraction process are combined, the phenol content in the gas phase at the top of the coal tar fractionating unit can be increased, so that the phenol content in the phenol-containing sewage in the reflux tank of the fractionating unit can be increased.

In the invention, the density of the first extracting agent is less than that of the phenol-containing oil, so that the first extracting agent can upwards depend on buoyancy to achieve the effect of countercurrent extraction; and when the secondary extraction is carried out, the neutral oil in the first extractant is extracted by the second extractant due to the principle of similar compatibility, and the neutral oil in the second extractant is recovered through a light oil recovery unit.

In the invention, the primary extraction phase contains phenolic substances, a first extractant and a small amount of neutral oil; the first-stage raffinate phase contains dephenolized oil and a small amount of first extractant; the secondary extraction phase comprises a secondary extraction and a small amount of neutral oil; the secondary raffinate phase contains a first extracting agent and phenolic substances.

In the invention, the dephenolized light oil obtained in the step (3) flows in from a first side inlet of a coal tar fractionating unit and is extracted and rectified; dephenolized heavy oil flows in from a second side inlet of the coal tar fractionating unit and is mixed with the phenol oil fraction of the corresponding fraction in the packed rectifying tower.

In the following, as a preferred embodiment of the present invention, the primary extractant in step (2) comprises an aqueous alcohol solution.

Preferably, the alcohol aqueous solution includes any one of a methanol aqueous solution, an ethanol aqueous solution, or a propanol aqueous solution.

Preferably, the mass ratio of the first extractant to the phenolic oil is (0.2-2: 1), for example 0.2:1, 0.5:1, 1:1, 1.2:1, 1.5:1 or 2:1, but not limited to the recited values, and other values not recited within this range of values are equally applicable.

Preferably, the temperature of the first extraction in step (2) is 20-60 ℃, such as 20 ℃, 30 ℃, 40 ℃, 50 ℃ or 60 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the pressure of the first extraction in step (2) is 100-800kPa, such as 100kPa, 200kPa, 300kPa, 400kPa, 500kPa, 600kPa, 700kPa, 800kPa, or the like, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

As a preferable technical scheme of the invention, the secondary extracting agent in the step (2) comprises an alkane solvent.

Preferably, the alkane solvent comprises hydrogenated light gasoline or cyclohexane.

In the invention, the distillation range of the hydrogenated light gasoline is 65-130 ℃.

Preferably, the mass ratio of the second extractant to the first extractant phase is (0.2-2):1, for example 0.2:1, 0.5:1, 1:1, 1.2:1, 1.5:1 or 2:1, but not limited to the recited values, and other values not recited within this range of values are equally applicable.

Preferably, the temperature of the secondary extraction in step (2) is 20-60 ℃, such as 20 ℃, 30 ℃, 40 ℃, 50 ℃ or 60 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the pressure of the secondary extraction in step (2) is 100-800kPa, such as 100kPa, 200kPa, 300kPa, 400kPa, 500kPa, 600kPa, 700kPa, 800kPa, or the like, but is not limited to the recited values, and other values not recited within the range are equally applicable.

Hereinafter, as a preferred embodiment of the present invention, the temperature of the water washing in the step (2) is 20 to 60 ℃, for example, 20 ℃, 30 ℃, 40 ℃, 50 ℃ or 60 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the pressure of the water wash in step (2) is 100-800kPa, such as 100kPa, 200kPa, 300kPa, 400kPa, 500kPa, 600kPa, 700kPa, 800kPa, or the like, but is not limited to the recited values, and other non-recited values within this range are equally applicable.

Preferably, the first extractant obtained after the water washing in the step (2) is returned for recycling.

Compared with the prior art, the invention has the following beneficial effects:

(1) the coupling device provided by the invention combines the design of a plurality of fractionation sections and a 2-stage extraction section, and is assisted by a water washing section and a low-temperature separation section, so that the environmental protection problems in the processes of extracting phenol from coal tar and distilling tar are solved, and the phenol content and the treatment cost in phenol-containing sewage are reduced;

(2) the coupling process improves the quality of a crude phenol product and reduces the content of impurity neutral oil by combining extractive distillation and liquid-liquid extraction, and the purity of phenol in the obtained crude phenol product reaches over 90.24 percent and the content of neutral oil (impurity) is below 0.85 percent by weight; the yield of the dephenolized oil is more than 89.60 percent, wherein the phenol content is less than 7.51 percent by weight, and the content of the first extractant is less than 0.86 percent by weight;

(3) the coupling process also greatly reduces the energy consumption of the rectification dehydration working section through low-temperature separation operation, and is beneficial to industrial application.

Drawings

Fig. 1 is a schematic connection structure diagram of a coal tar phenol-extracting and phenol-containing water treatment coupling device provided in embodiment 1 of the present invention.

FIG. 2 is a process flow diagram of a coal tar phenol extraction and phenol-containing water treatment coupling process provided in example 1 of the present invention;

FIG. 3 is a process flow diagram of a coal tar phenol extraction and phenol-containing water treatment coupling process provided by comparative example 1 of the present invention.

The method comprises the following steps of 1-coal tar fractionation unit, 2-first extraction unit, 3-second extraction unit, 4-light oil recovery unit, 5-first extractant recovery unit, 6-water washing unit, 7-dephenolized oil fractionation unit, 8-separation unit and 9-crude phenol dehydration unit.

Wherein the direction of the arrows represents the direction of material flow.

Detailed Description

It is to be understood that in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be taken as limiting the present invention. Furthermore, the terms "first," "second," "primary," "secondary," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first," "second," "primary," "secondary," etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

In one embodiment, the invention provides a coupling device for coal tar phenol extraction and phenol-containing water treatment, which comprises a coal tar fractionation unit 1, a first extraction unit 2, a second extraction unit 3, a light oil recovery unit 4, a first extractant recovery unit 5, a water washing unit 6, a dephenolized oil fractionation unit 7, a separation unit 8 and a crude phenol dehydration unit 9;

the coal tar fractionating unit 1 is connected with an extract liquid inlet of the first extraction unit 2;

an extract phase outlet of the first extraction unit 2 is connected with an extract liquid inlet of the second extraction unit 3; a raffinate phase outlet of the first extraction unit 2 is connected with the water washing unit 6; the water washing unit 6 is connected with the dephenolized oil fractionation unit 7;

an extract phase outlet of the second extraction unit 3 is connected with the light oil recovery unit 4; a raffinate phase outlet of the second extraction unit 3 is connected with the first extractant recovery unit 5;

a heavy component outlet of the light oil recovery unit 4 is connected with the dephenolized oil fractionation unit 7;

the heavy component outlet of the first extractant recovery unit 5 is connected with the separation unit 8; the separation unit 8 is connected with the crude phenol dehydration unit 9;

a light component outlet of the dephenolized oil fractionating unit 7 is connected with a first side inlet of the coal tar fractionating unit 1; and a heavy component outlet of the dephenolized oil fractionating unit 7 is connected with a second side inlet of the coal tar fractionating unit 1.

Further, the coal tar fractionation unit 1 comprises a packed rectification column; the packing rectifying tower at least comprises 4 packing sections, and the packing section close to the top is specified as a first packing section; a coal tar inlet is formed in the bottom end of the side wall of the filler rectifying tower; the top end of the packing rectifying tower is provided with a first light component outlet; a first side line inlet is arranged between the first packing section and the second packing section of the packing rectifying tower; a lateral line extraction port is arranged between the last two adjacent filler sections of the filler rectifying tower; a second side inlet is arranged between the first side inlet and the side outlet; the first light component outlet and the side draw outlet are both connected with an extract liquid inlet of the first extraction unit 2.

Further, the first extraction unit 2 comprises a first extraction column; an extract liquid inlet is formed in the top end of the side wall of the first extraction tower; a first extracting agent inlet is formed in the bottom end of the side wall of the first extracting tower; the second extraction unit 3 comprises a second extraction column; an extract liquid inlet is formed in the top end of the side wall of the second extraction tower; and a second extractant inlet is formed in the bottom end of the side wall of the second extraction tower.

Further, the light oil recovery unit 4 includes a first rectification column; the light component outlet of the light oil recovery unit 4 is connected with the second extractant inlet; the first extractant recovery unit 5 comprises a second rectification column; the light component outlet of the first extractant recovery unit 5 is connected with the first extractant inlet.

Further, the water washing unit 6 includes a water washing tower; a washing water inlet is formed in the top end of the side wall of the washing tower; an inlet for water to be washed is formed in the bottom end of the side wall of the water washing tower; the water washing unit 6 is also connected with the first extractant inlet; the dephenolized oil fractionation unit 7 comprises a third rectifying tower.

Further, the separation unit 8 comprises a separation tank; the separation unit 8 is also independently connected with the first extractant inlet and the water washing unit 6 respectively; the crude phenol dehydration unit 9 comprises a fourth rectifying tower; the light component outlet of the crude phenol dehydration unit 9 is also independently connected with the first extractant inlet and the water washing unit 6.

The following are typical but non-limiting examples of the invention:

example 1:

the embodiment provides a coupling device and a coupling process for phenol extraction from coal tar and phenol-containing water treatment, and the coupling device is based on the following specific implementation modes:

wherein, the filler rectifying tower is provided with 4 filler sections. Fig. 1 is a schematic diagram of a connection structure of the coupling device according to this embodiment.

The coupling process using the above coupling device includes the following steps, the process flow of which is shown in fig. 2,

(1) extracting and rectifying coal tar to obtain phenol-containing oil<230 ℃ phenolic oil with a density of 964.2kg/m at 40 DEG³Crude phenol content 36.7 wt%); when the extractive distillation is carried out, the extractant used is dephenolized light oil obtained after the third distillation in the step (3);

(2) performing primary extraction on the phenol-containing oil obtained in the step (1) by using a methanol-added aqueous solution (the mass ratio of the methanol aqueous solution to the phenol-containing oil is 1.4:1), and performing secondary extraction on the obtained primary extract phase by using cyclohexane (the mass ratio of the cyclohexane to the primary extract phase is 1:1) to obtain a secondary extract phase and a secondary raffinate phase;

washing the obtained first-stage raffinate phase with water to obtain a methanol aqueous solution and dephenolized oil; the methanol aqueous solution obtained after washing is returned to the first-stage extraction for recycling;

(3) performing first rectification on the secondary extract phase obtained in the step (2) to obtain cyclohexane and neutral oil; performing second rectification on the secondary raffinate phase obtained in the step (2) to obtain a methanol water solution and a crude phenol solution;

the obtained cyclohexane returns to the secondary extraction for recycling; mixing the neutral oil with the dephenolized oil obtained in the step (2) and then dividing the mixture into two parts, wherein one part obtains a dephenolized oil product, the other part obtains dephenolized light oil and dephenolized heavy oil after third rectification, and the dephenolized light oil and the dephenolized heavy oil are respectively returned to the step (1) for utilization;

the methanol aqueous solution obtained after the second rectification is returned to the first-stage extraction in the step (2) for recycling; the crude phenol solution is subjected to low-temperature separation and fourth rectification in sequence to obtain a crude phenol product; and (3) dividing the water obtained after the low-temperature separation and the fourth rectification into two parts, returning one part to the step (2) for primary extraction, and returning the other part to the step (2) for water washing.

The process parameters designed in the above coupling process are shown in table 1.

TABLE 1

Example 2:

the embodiment provides a coupling device and a coupling process for phenol extraction from coal tar and phenol-containing water treatment, and the coupling device is based on the following specific implementation modes:

wherein, the filler rectifying tower is provided with 4 filler sections.

The coupling process performed by adopting the coupling device comprises the following steps:

(1) performing extraction rectification on the coal tar to obtain phenol-containing oil; when the extractive distillation is carried out, the extractant used is dephenolized light oil obtained after the third distillation in the step (3);

(2) performing primary extraction on the phenol-containing oil obtained in the step (1) by using a methanol-added aqueous solution (the mass ratio of the methanol aqueous solution to the phenol-containing oil is 1:1), and performing secondary extraction on the obtained primary extract phase by using cyclohexane (the mass ratio of the cyclohexane to the primary extract phase is 0.7:1) to obtain a secondary extract phase and a secondary raffinate phase;

washing the obtained first-stage raffinate phase with water to obtain a methanol aqueous solution and dephenolized oil; the methanol aqueous solution obtained after washing is returned to the first-stage extraction for recycling;

(3) performing first rectification on the secondary extract phase obtained in the step (2) to obtain cyclohexane and neutral oil; performing second rectification on the secondary raffinate phase obtained in the step (2) to obtain a methanol water solution and a crude phenol solution;

the obtained cyclohexane returns to the secondary extraction for recycling; mixing the neutral oil with the dephenolized oil obtained in the step (2) and then dividing the mixture into two parts, wherein one part obtains a dephenolized oil product, the other part obtains dephenolized light oil and dephenolized heavy oil after third rectification, and the dephenolized light oil and the dephenolized heavy oil are respectively returned to the step (1) for utilization;

the methanol aqueous solution obtained after the second rectification is returned to the first-stage extraction in the step (2) for recycling; the crude phenol solution is subjected to low-temperature separation and fourth rectification in sequence to obtain a crude phenol product; and (3) dividing the water obtained after the low-temperature separation and the fourth rectification into two parts, returning one part to the step (2) for primary extraction, and returning the other part to the step (2) for water washing.

The process parameters designed in the above coupling process are shown in table 2.

TABLE 2

Comparative example 1:

this comparative example provides an apparatus and process for phenol extraction from coal tar and phenol-containing water treatment, the apparatus being referenced to the coupling apparatus of example 1, except that: the second extraction unit 3 and the light oil recovery unit 4 are not included.

Accordingly, the connection relationship is changed as follows:

the extract phase outlet of the first extraction unit 2 is connected with the first extractant recovery unit 5.

The process for extracting phenol from coal tar and treating phenol-containing water by adopting the device refers to the coupling process in the embodiment 1, and the difference is that: not only the second extraction and the first rectification are carried out. The process flow diagram of this comparative example is shown in fig. 3.

Comparative example 2:

this comparative example provides an apparatus and process for phenol extraction from coal tar and phenol-containing water treatment, the apparatus being referenced to the coupling apparatus of example 1, except that: a light component outlet of the dephenolized oil fractionating unit 7 is not connected with a first side inlet of the coal tar fractionating unit 1; and a heavy component outlet of the dephenolized oil fractionating unit 7 is not connected with a second side inlet of the coal tar fractionating unit 1.

The process flow using the above apparatus is referred to the coupling process in example 1, with the difference that: and (4) the dephenolized light oil and the dephenolized heavy oil obtained after the third rectification in the step (3) are not returned to the step (1).

The purity and neutral oil content of the phenol in the crude phenol products obtained in examples 1-2 and comparative example 1 were measured; and the content of the first extractant in the obtained dephenolized oil, the yield of the dephenolized oil and the phenol content, and the results are shown in table 3.

The recovery rate of phenol and the content of neutral oil in the crude phenol products obtained in examples 1-2 and comparative example 2 were measured; and the content of the first extractant in the obtained dephenolized oil, the yield of the dephenolized oil and the phenol content, and the results are shown in table 4.

TABLE 3

TABLE 4

In the comparative example 1, only the first-stage extraction is carried out, so that the content of neutral oil (impurities) in the finally obtained crude phenol product is up to 17.98 wt%, and the product quality is seriously reduced; in comparative example 2, conventional rectification was combined with the second-stage extraction, resulting in a higher phenol content in the resulting dephenolized oil.

It can be seen from the above examples and comparative examples that the coupling device of the present invention combines the design of multiple fractionation sections and 2-stage extraction sections, and is assisted by a water washing section and a low temperature separation section, thereby solving the environmental protection problem in the processes of phenol extraction from coal tar and distillation of tar, and effectively reducing the treatment cost; the coupling process improves the quality of a crude phenol product and reduces the content of impurity neutral oil by combining extractive distillation and liquid-liquid extraction, and the purity of phenol in the obtained crude phenol product reaches over 90.24 percent and the content of neutral oil (impurity) is below 0.85 percent by weight; the yield of the dephenolized oil is more than 89.60 percent, wherein the phenol content is less than 7.51 percent by weight, and the content of the first extractant is less than 0.86 percent by weight; in addition, the energy consumption of crude phenol dehydration is greatly reduced through low-temperature separation operation, and the method is favorable for industrial application.

The applicant states that the present invention is illustrated by the above embodiments of the present invention, but the present invention is not limited to the above embodiments, i.e. it is not meant to imply that the present invention must be implemented by means of the above embodiments. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents thereof, additions of additional operations, selection of specific ways, etc., are within the scope and disclosure of the present invention.