Device and method for extracting crude phenol from phenol-containing distillate oil and performing zero discharge treatment on wastewater

Abstract

The invention relates to a device and a method for extracting crude phenol from phenol-containing distillate oil and performing zero discharge treatment on wastewater. The device comprises an alkaline washing tower, a stripping tower, a decomposition tower, an extraction machine, a regenerator, an adsorption tower, a complexing tank, an alkali preparation tank and a crystallizer, the method comprises the following steps: S1, preparing dilute alkali; s2, carbolic oil alkali washing; s3, stripping to remove impurities; s4, acidizing and decomposing; s5, extracting and dephenolizing; s6, regenerating the extracting agent; s7, adsorption and dephenolization; s8, complexing and removing impurities; and S9, crystallizing and desalting. The method provided by the invention can realize extraction of crude phenol from carbolic oil and zero discharge of wastewater, and thoroughly solves the problem of environmental protection in acid-base phenol extraction of coal tar.

Description

Technical Field

[0001] The invention relates to the technical field of coal chemical industry and comprehensive utilization of coal tar, and in particular to a device and method for extracting crude phenol from phenol-containing fraction oil and treating wastewater with zero discharge. Background Art

[0002] Coal tar is a black or dark brown viscous liquid with a pungent odor. It is a liquid product produced during the pyrolysis of coal. Coal tar is an important raw material for coal chemical industry. It has rich chemical composition and a wide range of uses. The coal tar industry should continue to develop and contribute to the economy and the environment. However, the production process of coal tar will produce a large amount of pollutants such as waste gas, wastewater and waste residue, which will have a certain impact on the environment and ecology. Therefore, in the production and use of coal tar, effective environmental protection measures need to be taken to reduce the emission of pollutants and protect the environment and ecology.

[0003] Phenol is one of the important chemical raw materials. In recent years, with the development of phenol downstream products, the demand for phenol is increasing year by year. At present, the domestic supply is in short supply and imports are required every year. In coal tar, 86% of phenol is mainly concentrated in phenol oil, naphthalene oil, and phenol fraction oil in washing oil fraction. With the extension of the downstream industrial chain, the market demand for crude phenol increases year by year. At present, the acid-base method is one of the main ways to extract crude phenol from coal tar. The process has the advantages of high efficiency, high yield, fast reaction and low cost. However, the acid-base method for extracting phenol will produce salt-containing and phenol-containing wastewater, which will cause harm to the environment. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and provides a device and method for extracting crude phenol from phenol-containing distillate oil and for treating wastewater with zero discharge.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, comprising an alkali washing tower, a stripping tower, a decomposition tower, an extractor, a regenerator, an adsorption tower, a complexing tank, an alkali preparation tank and a crystallizer;

[0007] The alkali preparation tank is connected with a solid alkali supply pipeline, the production pipeline at the top of the crystallizer is connected with the alkali preparation tank, the diluted alkali outlet of the alkali preparation tank is respectively connected with the upper part of the alkali washing tower, the upper part of the regenerator and the upper part of the adsorption tower through pipelines, the lower part of the alkali washing tower is connected with a phenol fraction oil pipeline, the bottom of the alkali washing tower is connected with the upper part of the stripping tower through a pipeline, the bottom of the stripping tower is connected with the decomposition tower through a pipeline, the decomposition tower is connected with an acidic substance supply pipeline, the sodium salt solution outlet of the decomposition tower is connected with the upper part of the extractor through a pipeline, the lower part of the extractor is connected with an extractant supply pipeline, the production pipeline at the top of the extractor is connected with the lower part of the regenerator, the production pipeline at the bottom of the extractor is connected with the top of the adsorption tower, the production pipeline at the top of the regenerator is connected with the extractant supply pipeline, the production pipeline at the bottom of the regenerator is connected with the decomposition tower, the production pipeline at the bottom of the adsorption tower is connected with the upper part of the complexing tank, the regeneration outlet of the adsorption tower is connected with the decomposition tower, the complexing tank is connected with a complexing agent pipeline, and the complexing tank is connected with the crystallizer.

[0008] The alkali washing tower is operated as a single unit or as multiple units in cascade, and the number of stages of the alkali washing tower is 1-6.

[0009] The extractor is operated as a single unit or in series, and the number of stages of the extractor is 1-6; when the extractor is operated as a single unit, the extractor is any one of a tower, a stirring tank, and a centrifuge; when the extractor is operated as a multiple unit, the extractor is any one of a tower, a stirring tank, and a centrifuge in series or in any combination of towers, stirring tanks, and centrifuges.

[0010] The regenerator is operated as a single unit or in cascade, and the number of stages of the regenerator is 1-6; when the regenerator is operated as a single unit, the regenerator is any one of a tower, a stirring tank, and a centrifuge; when the regenerator is operated as a multiple unit, the regenerator is any one of a tower, a stirring tank, and a centrifuge in cascade alone or in any combination of towers, stirring tanks, and centrifuges.

[0011] A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, using the above-mentioned device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, and the specific steps are:

[0012] S1. Preparation of dilute alkali:

[0013] The desalted wastewater from the subsequent crystallizer and the solid alkali are used to prepare the diluted alkali in the alkali preparation tank, the concentration of the diluted alkali is 2%-50%, the operating temperature in the alkali preparation tank is 25℃-100℃, and the pressure is 0MPa(g)-0.6MPa(g);

[0014] S2, phenol oil alkali washing:

[0015] The phenol-containing distillate oil enters the alkali washing tower from the lower part, and contacts with the dilute alkali entering from the upper part of the alkali washing tower in countercurrent, the volume ratio of the dilute alkali washing tower to the phenol-containing distillate oil is 1:100, the operating temperature is 25°C-100°C, the operating pressure is 0MPa(g)-0.6MPa(g), the dephenolized oil is produced at the top of the alkali washing tower, and the phenol sodium salt solution is produced at the bottom of the alkali washing tower;

[0016] S3, stripping and impurity removal:

[0017] The sodium phenol salt solution enters from the upper part of the stripping tower. The stripping tower kettle adopts indirect or direct heating, the operating temperature is 100℃-180℃, the operating pressure is 0MPa(g)-0.6MPa(g), the neutral oil rises to the top of the tower after being vaporized in the tower kettle, the liquid neutral oil is produced after condensation and cooling at the top of the tower, and the clean sodium phenol salt solution with the neutral oil removed is produced in the tower kettle, and the clean sodium phenol salt solution is sent to the decomposition tower after the temperature is reduced by the cooler;

[0018] S4. Acidification and decomposition:

[0019] An acidic substance with stronger acidity than phenol is added into a decomposition tower, and sodium phenolate reacts with the acidic substance to undergo a decomposition reaction, wherein the concentration of the acidic substance is 10%-100%, the volume ratio of the acidic substance to the sodium phenolate solution is 1:1000, the operating temperature is 100°C-180°C, and the operating pressure is 0MPa(g)-0.6MPa(g). After the reaction is completed, crude phenol and a sodium salt solution are produced, the crude phenol and the sodium salt solution are separated into layers, the upper layer is the crude phenol, and the lower layer is the sodium salt solution, and the sodium salt solution enters an extractor for extraction and dephenolization;

[0020] S5, extraction and dephenolization:

[0021] The sodium salt solution enters from the upper part of the extractor and contacts with the extractant entering from the lower part of the extractor in countercurrent. The volume ratio of the extractant to the sodium salt solution is 1:100. The operating temperature is 100°C-180°C. The operating pressure is 0MPa(g)-0.6MPa(g). The phenol-containing extractant is extracted from the top of the extractor and used as the feed of the regenerator. The extraction dephenolization wastewater is extracted from the bottom of the extractor and used as the feed of the adsorption tower.

[0022] S6. Extractant regeneration:

[0023] The phenol-containing extractant enters from the lower part of the regenerator and contacts with the dilute alkali entering from the upper part of the regenerator in countercurrent. The volume ratio of the dilute alkali to the phenol-containing distillate oil is 1:100. The operating temperature is 25°C-100°C and the operating pressure is 0MPa(g)-0.6MPa(g). The extractant is taken out from the top of the regenerator and returned to the extractant for recycling. The sodium phenol salt solution is taken out from the bottom of the regenerator and sent to the decomposition tower as the feed for acidification decomposition.

[0024] S7, adsorption dephenolization:

[0025] The extraction dephenolization wastewater enters from the top of the adsorption tower, and the adsorption tower is equipped with an adsorption filler. The extraction dephenolization wastewater passes through the adsorption filler, and the phenolic substances in the wastewater are adsorbed by the adsorption filler. The adsorption dephenolization wastewater is extracted at the bottom of the adsorption tower, and the adsorption dephenolization wastewater is used as the feed of the complexing tank. When the adsorption filler is saturated, a dilute alkali is introduced into the adsorption tower, and the dilute alkali reacts with the phenol on the surface of the adsorption filler to produce a sodium phenolate solution. The sodium phenolate solution is extracted at the bottom of the adsorption column, and the sodium phenolate solution is sent to a decomposition tower. After the sodium phenolate is drained, the regenerated adsorption column is recycled, and the operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g);

[0026] S8, complexation and decontamination:

[0027] The adsorption dephenolization wastewater enters from the upper part of the complexing tank, and a complexing agent is added into the complexing tank. The complexing agent adopts a 0.1%-30% dilute solution, and the mass ratio of the complexing agent to the adsorption dephenolization wastewater is: 1:1000. The operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g). The coloring substance in the adsorption dephenolization wastewater reacts with the complexing agent to form a precipitate. The complexing precipitate is separated from the bottom of the complexing tank to obtain decolorized wastewater, and the decolorized wastewater is used as the feed of the crystallizer;

[0028] S9, Crystallization Desalination:

[0029] The decolorized wastewater is sent to the crystallizer, which uses heating or freezing to perform desalination. The operating temperature of the crystallization desalination is -25℃-200℃, and the operating pressure is -0.1MPa(g)-0.6MPa(g). Finally, inorganic salts are obtained at the bottom of the crystallizer, and circulating water is obtained at the top of the crystallizer. The circulating water returns to the alkali preparation tank and is used as raw material for the preparation of dilute alkali, thereby achieving zero wastewater discharge in the entire process.

[0030] In step S4, the acidic substance is carbon dioxide, sulfuric acid, or a combination of carbon dioxide and sulfuric acid in any ratio.

[0031] In step S5, the extractant is one of toluene, xylene, methyl isobutyl ketone, methyl tert-butyl ketone, diisopropyl ether, methyl tert-amyl ether, butyl acetate, sec-butyl acetate, dimethyl carbonate, 2-ethylhexyl phosphate-2-ethylhexyl ester, methyldiethanolamine, N,N-bis(1-methylheptyl)acetamide, dihexylpropanolamine, cyclopentane sulfone, and petroleum ether, or a combination of any of the above.

[0032] In step S7, the adsorption filler is one or any combination of activated carbon, resin, coke, blue charcoal, and membrane.

[0033] In step S8, the complexing agent is a compound containing any one or more combinations of sodium ions, calcium ions or molecules, magnesium ions or molecules, copper ions or molecules, iron ions or molecules, aluminum ions or molecules, zinc ions or molecules, thiosulfate, carbonate, sulfate, hydroxyl, and carbon chain groups.

[0034] In step S9, crystallization desalination includes one or any combination of single-effect evaporation, multiple-effect evaporation, MVR, and freezing crystallization.

[0035] The beneficial effects of the present invention are as follows: the present invention can realize the extraction of crude phenol from phenol oil and zero discharge of waste water, and completely solves the environmental protection problem of the acid-base phenol extraction process from coal tar. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a connection diagram of the processing device in the present invention;

[0037] In the figure: 1-alkali washing tower; 2-stripping tower; 3-decomposition tower; 4-extractor; 5-regenerator; 6-adsorption tower; 7-complexation tank; 8-alkali preparation tank; 9-crystallizer; 10-solid alkali supply pipeline; 11-phenol fraction oil pipeline; 12-acidic substance supply pipeline; 13-extractant supply pipeline; 14-complexing agent pipeline;

[0038] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The embodiments are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0042] A device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, such as Figure 1 As shown, it includes an alkali washing tower 1, a stripping tower 2, a decomposition tower 3, an extractor 4, a regenerator 5, an adsorption tower 6, a complexing tank 7, an alkali preparation tank 8 and a crystallizer 9.

[0043] The alkali preparation tank 8 is connected to a solid alkali supply pipeline 10, the extraction pipeline at the top of the crystallizer 9 is connected to the alkali preparation tank 8, the dilute alkali outlet of the alkali preparation tank 8 is connected to the upper part of the alkali washing tower 1, the upper part of the regenerator 5, and the upper part of the adsorption tower 6 through pipelines, the lower part of the alkali washing tower 1 is connected to a phenol fraction oil pipeline 11, the bottom of the alkali washing tower 1 is connected to the upper part of the stripping tower 2 through a pipeline, the bottom of the stripping tower 2 is connected to the decomposition tower 3 through a pipeline, the decomposition tower 3 is connected to an acidic substance supply pipeline 12, and the sodium salt solution outlet of the decomposition tower 3 is connected to the extraction machine through a pipeline. 4, the lower part of the extractor 4 is connected with the extractant supply pipeline 13, the top extraction pipeline of the extractor 4 is connected with the lower part of the regenerator 5, the bottom extraction pipeline of the extractor 4 is connected with the top of the adsorption tower 6, the top extraction pipeline of the regenerator 5 is connected with the extractant supply pipeline 13, the bottom extraction pipeline of the regenerator 5 is connected with the decomposition tower 3, the bottom extraction pipeline of the adsorption tower 6 is connected with the upper part of the complexing tank 7, the regeneration outlet of the adsorption tower 6 is connected with the decomposition tower 3, the complexing tank 7 is connected with the complexing agent pipeline 14, and the complexing tank 7 is connected with the crystallizer 9.

[0044] The alkali washing tower 1 is operated as a single unit or as a plurality of units in cascade, and the number of stages of the alkali washing tower 1 is 1 to 6. When the alkali washing tower 1 is multi-stage, the dilute alkali enters from the upper part of the first tower and contacts with the phenol-containing fraction oil entering from the lower part of the last tower in countercurrent, and finally the dephenolized oil is produced at the top of the first tower, and the sodium phenol salt solution is produced at the bottom of the last tower.

[0045] The extractor 4 is operated as a single unit or as a plurality of units in cascade, and the number of stages of the extractor 4 is 1-6; when the extractor 4 is operated as a single unit, the extractor 4 is any one of a tower, a stirring tank, and a centrifuge; when the extractor 4 is operated as a plurality of units in cascade, the extractor 4 is any one of a tower, a stirring tank, and a centrifuge in cascade alone or in any combination of the tower, the stirring tank, and the centrifuge.

[0046] The regenerator 5 is operated as a single unit or as a plurality of units in cascade, and the number of stages of the regenerator 5 is 1-6; when the regenerator 5 is operated as a single unit, the regenerator 5 is any one of a tower, a stirring tank, and a centrifuge; when the regenerator 5 is operated as a plurality of units in cascade, the regenerator 5 is any one of a tower, a stirring tank, and a centrifuge in cascade alone or in any combination of the tower, the stirring tank, and the centrifuge.

[0047] A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, using the above-mentioned device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, and the specific steps are:

[0048] S1. Preparation of dilute alkali:

[0049] The desalted wastewater from the subsequent crystallizer 9 and the solid alkali are used to prepare the diluted alkali in the alkali preparation tank 8, the concentration of the diluted alkali is 2%-50%, the operating temperature in the alkali preparation tank 8 is 25°C-100°C, and the pressure is 0MPa(g)-0.6MPa(g);

[0050] Dilute alkali is used as the raw material for phenol oil alkaline washing, extractant regeneration and adsorption regeneration.

[0051] S2, phenol oil alkali washing:

[0052] The phenol-containing distillate oil enters the alkali washing tower 1 from the lower part, and contacts with the dilute alkali entering from the upper part of the alkali washing tower 1 in countercurrent. The volume ratio of the dilute washing tower 1 to the phenol-containing distillate oil is 1:100. The operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g). The phenol-containing distillate oil consists of phenol oil and neutral oil. The phenol oil reacts with the dilute alkali to generate a sodium phenol salt solution. The remaining fraction is dephenolized oil. The sodium phenol salt solution has a higher specific gravity than the dephenolized oil and is insoluble in the dephenolized oil. Thus, the dephenolized oil is extracted from the top of the alkali washing tower 1 and sold as a by-product. The sodium phenol salt solution is extracted from the bottom of the alkali washing tower 1. The sodium phenol salt solution is used as a raw material for crude phenol production.

[0053] S3, stripping and impurity removal:

[0054] The sodium phenol salt solution enters from the upper part of the stripping tower 2. The bottom of the stripping tower 2 is heated indirectly or directly. The operating temperature is 100°C-180°C and the operating pressure is 0MPa(g)-0.6MPa(g). The sodium phenol salt solution contains a small amount of neutral oil. The neutral oil impurities are removed by stripping to obtain a clean sodium phenol salt solution without neutral oil impurities. The neutral oil rises to the top of the tower after being vaporized in the bottom of the tower. The liquid neutral oil is extracted after condensation and cooling at the top of the tower. The neutral oil is sold as a by-product. The clean sodium phenol salt solution with the neutral oil removed is extracted in the bottom of the tower. The clean sodium phenol salt solution is sent to the decomposition tower 3 after the temperature is reduced by the cooler.

[0055] S4. Acidification and decomposition:

[0056] Sodium phenolate can decompose with a substance stronger than phenol acid. In the decomposition tower 3, an acidic substance stronger than phenol acid is added. Sodium phenolate decomposes with the acidic substance. The concentration of the acidic substance is 10%-100%. The volume ratio of the acidic substance to the sodium phenolate solution is 1:1000. The operating temperature is 100°C-180°C, and the operating pressure is 0MPa(g)-0.6MPa(g). After the reaction is completed, crude phenol and sodium salt solution (sodium carbonate or sodium sulfate) are produced. Since the crude phenol is relatively small, and the crude phenol is insoluble in the sodium salt solution, the crude phenol and the sodium salt solution are layered. The upper strata are crude phenol, and the lower strata are sodium salt solution. The crude phenol is sold as a product. The sodium salt solution contains a small amount of phenolic substances, and the sodium salt solution enters an extractor 4 for extraction and dephenolation.

[0057] The acidic substance is carbon dioxide, sulfuric acid or a combination of carbon dioxide and sulfuric acid in any ratio.

[0058] S5, extraction and dephenolization:

[0059] The sodium salt solution contains a small amount of phenolic compounds and needs to be dephenolized. The sodium salt solution enters from the upper part of the extractor 4 and contacts with the extractant entering from the lower part of the extractor 4 in countercurrent. The volume ratio of the extractant to the sodium salt solution is 1:100. The operating temperature is 100° C.-180° C., and the operating pressure is 0 MPa(g)-0.6 MPa(g). The phenol-containing extractant is extracted from the top of the extractor 4 and used as the feed of the regenerator 5. The extracted dephenolized wastewater is extracted from the bottom of the extractor 4 and used as the feed of the adsorption tower 6.

[0060] The extractant is one of toluene, xylene, methyl isobutyl ketone, methyl tert-butyl ketone, diisopropyl ether, methyl tert-amyl ether, butyl acetate, sec-butyl acetate, dimethyl carbonate, 2-ethylhexyl phosphate-2-ethylhexyl ester, methyldiethanolamine, N,N-bis(1-methylheptyl)acetamide, dihexylpropanolamine, cyclopentane sulfone, and petroleum ether, or a combination of any of the above.

[0061] S6. Extractant regeneration:

[0062] The phenol-containing extractant enters from the lower part of the regenerator 5 and contacts with the dilute alkali entering from the upper part of the regenerator 5 in countercurrent. The volume ratio of the dilute alkali to the phenol-containing distillate oil is 1:100. The operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g). The extractant is extracted from the top of the regenerator 5 and returned to the extractor 4 for recycling. The sodium phenol salt solution is extracted from the bottom of the regenerator 5 and is sent to the decomposition tower 3 as a feed for acidification decomposition.

[0063] S7, adsorption dephenolization:

[0064] The extraction dephenolation wastewater enters from the top of the adsorption tower 6, and the adsorption tower 6 is equipped with an adsorption filler. The extraction dephenolation wastewater passes through the adsorption filler, and the phenolic substances in the wastewater are adsorbed by the adsorption filler. The adsorption dephenolation wastewater is extracted at the bottom of the adsorption tower 6, and the adsorption dephenolation wastewater is used as the feed of the complexing tank 7. When the adsorption filler is saturated, a dilute alkali is introduced into the adsorption tower 6, and the dilute alkali reacts with phenol on the surface of the adsorption filler to produce a sodium phenolate solution. The sodium phenolate solution is extracted at the bottom of the adsorption column, and the sodium phenolate solution is sent to the decomposition tower 3. After the sodium phenolate is drained, the adsorption tower is regenerated, and the regenerated adsorption column is recycled. The operating temperature is 25° C.-100° C., and the operating pressure is 0 MPa(g)-0.6 MPa(g);

[0065] The adsorption filler is one of activated carbon, resin, coke, blue carbon, and membrane, or any combination of several of them.

[0066] S8, complexation and decontamination:

[0067] The adsorption dephenolation wastewater contains color-developing ions, molecules, etc. The adsorption dephenolation wastewater enters from the upper part of the complexing tank 7, and a complexing agent is added into the complexing tank 7. The complexing agent adopts a 0.1%-30% dilute solution, and the mass ratio of the complexing agent to the adsorption dephenolation wastewater is: 1:1000. The operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g). The color-developing substance in the adsorption dephenolation wastewater reacts with the complexing agent to form a precipitate, and the complexed precipitate is separated from the bottom of the complexing tank 7 to obtain decolorized wastewater, and the decolorized wastewater is used as the feed of the crystallizer 9;

[0068] The complexing agent is a compound containing any one or more combinations of sodium ions, calcium ions or molecules, magnesium ions or molecules, copper ions or molecules, iron ions or molecules, aluminum ions or molecules, zinc ions or molecules, thiosulfate, carbonate, sulfate, hydroxyl, and carbon chain groups.

[0069] S9, Crystallization Desalination:

[0070] The decolorized wastewater is sent to the crystallizer 9, which uses heating or freezing to perform desalination. The operating temperature of crystallization desalination is -25°C-200°C, and the operating pressure is -0.1MPa(g)-0.6MPa(g). Crystallization desalination includes one or any combination of single-effect evaporation, multiple-effect evaporation, MVR, and freezing crystallization. Finally, inorganic salts are obtained at the bottom of the crystallizer 9, and device circulating water is obtained at the top of the crystallizer 9. The device circulating water is low-concentration wastewater. The device circulating water returns to the alkali preparation tank 8 and is used as a raw material for the preparation of dilute alkali, thereby achieving zero wastewater discharge in the entire process.

[0071] The invention can realize the extraction of crude phenol from phenol oil and zero discharge of waste water, and completely solves the environmental protection problem in the acid-base phenol extraction process of coal tar.

[0072] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, characterized in that: It comprises an alkali washing tower (1), a stripping tower (2), a decomposition tower (3), an extractor (4), a regenerator (5), an adsorption tower (6), a complexing tank (7), an alkali preparation tank (8) and a crystallizer (9); The alkali preparation tank (8) is connected to a solid alkali supply pipeline (10), the extraction pipeline at the top of the crystallizer (9) is connected to the alkali preparation tank (8), the diluted alkali outlet of the alkali preparation tank (8) is respectively connected to the upper part of the alkali washing tower (1), the upper part of the regenerator (5), and the upper part of the adsorption tower (6) through pipelines, the lower part of the alkali washing tower (1) is connected to a phenol fraction oil pipeline (11), the bottom of the alkali washing tower (1) is connected to the upper part of the stripping tower (2) through a pipeline, the bottom of the stripping tower (2) is connected to the decomposition tower (3) through a pipeline, the decomposition tower (3) is connected to an acidic substance supply pipeline (12), and the sodium salt solution outlet of the decomposition tower (3) is connected to the extraction machine (4) through a pipeline. ), the lower part of the extractor (4) is connected to an extractant supply pipeline (13), the top extraction pipeline of the extractor (4) is connected to the lower part of the regeneration machine (5), the bottom extraction pipeline of the extractor (4) is connected to the top of the adsorption tower (6), the top extraction pipeline of the regeneration machine (5) is connected to the extractant supply pipeline (13), the bottom extraction pipeline of the regeneration machine (5) is connected to the decomposition tower (3), the bottom extraction pipeline of the adsorption tower (6) is connected to the upper part of the complexing tank (7), the regeneration outlet of the adsorption tower (6) is connected to the decomposition tower (3), the complexing tank (7) is connected to a complexing agent pipeline (14), and the complexing tank (7) is connected to a crystallizer (9).

2. The device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 1, characterized in that: The alkali washing tower (1) is operated as a single unit or as a plurality of units in cascade, and the number of stages of the alkali washing tower (1) is 1-6.

3. The device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 1, characterized in that: The extractor (4) is operated as a single unit or as a plurality of units in cascade, and the number of stages of the extractor (4) is 1-6; when the extractor (4) is operated as a single unit, the extractor (4) is any one of a tower, a stirring tank, and a centrifuge; when the extractor (4) is operated as a plurality of units in cascade, the extractor (4) is any one of a tower, a stirring tank, and a centrifuge in cascade alone or in any combination of the tower, the stirring tank, and the centrifuge.

4. The device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 1, characterized in that: The regenerator (5) is operated as a single unit or as a plurality of units in cascade, and the number of stages of the regenerator (5) is 1-6; when the regenerator (5) is operated as a single unit, the regenerator (5) is any one of a tower, a stirring tank, and a centrifuge; when the regenerator (5) is operated as a plurality of units in cascade, the regenerator (5) is any one of a tower, a stirring tank, and a centrifuge in cascade alone or in any combination of the tower, the stirring tank, and the centrifuge.

5. A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge, using the device for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge as claimed in any one of claims 1 to 4, characterized in that: The specific steps are: S1. Preparation of dilute alkali: The desalted wastewater from the subsequent crystallizer (9) and the solid alkali are used to prepare the diluted alkali in the alkali preparation tank (8), the concentration of the diluted alkali is 2%-50%, the operating temperature in the alkali preparation tank (8) is 25°C-100°C, and the pressure is 0MPa(g)-0.6MPa(g); S2, phenol oil alkali washing: The phenol-containing fraction oil enters the alkali washing tower (1) from the lower part and is countercurrently contacted with the dilute alkali entering from the upper part of the alkali washing tower (1). The volume ratio of the dilute alkali to the phenol-containing fraction oil is 1:

100. The operating temperature is 25° C.-100° C., and the operating pressure is 0 MPa(g)-0.6 MPa(g). The dephenolized oil is produced at the top of the alkali washing tower (1), and the sodium phenol salt solution is produced at the bottom of the alkali washing tower (1). S3, stripping and impurity removal: The sodium phenol salt solution enters the stripping tower (2) from the upper part. The bottom of the stripping tower (2) is heated indirectly or directly. The operating temperature is 100° C.-180° C. and the operating pressure is 0 MPa(g)-0.6 MPa(g). The neutral oil is vaporized in the bottom of the tower and rises to the top of the tower. The liquid neutral oil is extracted after condensation and cooling at the top of the tower. The clean sodium phenol salt solution with the neutral oil removed is extracted in the bottom of the tower. The clean sodium phenol salt solution is sent to the decomposition tower (3) after the temperature is reduced by a cooler. S4. Acidification and decomposition: An acidic substance with stronger acidity than phenol is added into a decomposition tower (3), and sodium phenolate reacts with the acidic substance to undergo a decomposition reaction. The concentration of the acidic substance is 10%-100%, the volume ratio of the acidic substance to the sodium phenolate solution is 1:1000, the operating temperature is 100° C.-180° C., and the operating pressure is 0 MPa(g)-0.6 MPa(g). After the reaction is completed, crude phenol and a sodium salt solution are produced. The crude phenol and the sodium salt solution are separated into layers, the upper layer is the crude phenol, and the lower layer is the sodium salt solution. The sodium salt solution enters an extractor (4) for extraction and dephenolization; S5, extraction and dephenolization: The sodium salt solution enters from the upper part of the extractor (4) and contacts with the extractant entering from the lower part of the extractor (4) in countercurrent, the volume ratio of the extractant to the sodium salt solution is 1:100, the operating temperature is 100° C.-180° C., the operating pressure is 0 MPa(g)-0.6 MPa(g), the phenol-containing extractant is extracted from the top of the extractor (4), and the phenol-containing extractant is used as the feed of the regeneration machine (5), and the extraction dephenolization wastewater is extracted from the bottom of the extractor (4), and the extraction dephenolization wastewater is used as the feed of the adsorption tower (6); S6. Extractant regeneration: The phenol-containing extractant enters from the lower part of the regenerator (5) and is countercurrently contacted with the diluted alkali entering from the upper part of the regenerator (5). The volume ratio of the diluted alkali to the phenol-containing fraction oil is 1:

100. The operating temperature is 25° C.-100° C. and the operating pressure is 0 MPa(g)-0.6 MPa(g). The extractant is extracted from the top of the regenerator (5) and returned to the extractant (4) for recycling. The sodium phenol salt solution is extracted from the bottom of the regenerator (5) and is sent to the decomposition tower (3) as a feed for acidification decomposition. S7, adsorption dephenolization: The extraction dephenolization wastewater enters from the top of the adsorption tower (6), and the adsorption tower (6) is equipped with an adsorption filler. The extraction dephenolization wastewater passes through the adsorption filler, and the phenolic substances in the wastewater are adsorbed by the adsorption filler. The adsorption dephenolization wastewater is sampled at the bottom of the adsorption tower (6), and the adsorption dephenolization wastewater is used as the feed of the complexing tank (7). When the adsorption filler is saturated, a dilute alkali is introduced into the adsorption tower (6), and the dilute alkali reacts with the phenol on the surface of the adsorption filler to produce a sodium phenolate solution. The sodium phenolate solution is sampled at the bottom of the adsorption column, and the sodium phenolate solution is sent to the decomposition tower (3). After the sodium phenolate is drained, the regenerated adsorption column is recycled, and the operating temperature is 25° C.-100° C., and the operating pressure is 0 MPa(g)-0.6 MPa(g); S8, complexation and decontamination: The adsorption dephenolization wastewater enters from the upper part of the complexing tank (7), and a complexing agent is added into the complexing tank (7). The complexing agent adopts a 0.1%-30% dilute solution, and the mass ratio of the complexing agent to the adsorption dephenolization wastewater is 1:1000. The operating temperature is 25°C-100°C, and the operating pressure is 0MPa(g)-0.6MPa(g). The coloring substance in the adsorption dephenolization wastewater reacts with the complexing agent to form a precipitate. The complexing precipitate is separated from the bottom of the complexing tank (7) to obtain decolorized wastewater, and the decolorized wastewater is used as the feed of the crystallizer (9); S9, Crystallization Desalination: The decolorized wastewater is sent to the crystallizer (9), and the crystallizer (9) is desalinated by heating or freezing. The crystallization desalination operating temperature is -25°C-200°C, and the operating pressure is -0.1MPa(g)-0.6MPa(g). Finally, inorganic salts are obtained at the bottom of the crystallizer (9), and device circulating water is obtained at the top of the crystallizer (9). The device circulating water returns to the alkali preparation tank (8) and is used as a raw material for the preparation of dilute alkali, thereby achieving zero wastewater discharge in the entire process.

6. A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 5, characterized in that: In step S4, the acidic substance is carbon dioxide, sulfuric acid, or a combination of carbon dioxide and sulfuric acid in any ratio.

7. A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 6, characterized in that: In step S5, the extractant is one of toluene, xylene, methyl isobutyl ketone, methyl tert-butyl ketone, diisopropyl ether, methyl tert-amyl ether, butyl acetate, sec-butyl acetate, dimethyl carbonate, 2-ethylhexyl phosphate-2-ethylhexyl ester, methyldiethanolamine, N,N-bis(1-methylheptyl)acetamide, dihexylpropanolamine, cyclopentane sulfone, and petroleum ether, or a combination of any of the above.

8. The method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 7, characterized in that: In step S7, the adsorption filler is one or any combination of activated carbon, resin, coke, blue charcoal, and membrane.

9. A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 8, characterized in that: In step S8, the complexing agent is a compound containing any one or more combinations of sodium ions, calcium ions or molecules, magnesium ions or molecules, copper ions or molecules, iron ions or molecules, aluminum ions or molecules, zinc ions or molecules, thiosulfate, carbonate, sulfate, hydroxyl, and carbon chain groups.

10. A method for extracting crude phenol from phenol-containing distillate oil and treating wastewater with zero discharge according to claim 9, characterized in that: In step S9, crystallization desalination includes one or any combination of single-effect evaporation, multiple-effect evaporation, MVR, and freezing crystallization.

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