A method for separating phenol and acetophenone from tar

Abstract

The present invention relates to a method for separating phenol and acetophenone from tar, comprising: a deweighting tower for removing heavy components from tar, the tower bottom of the deweighting tower extracts tar heavy components; a coarse fractionation tower, whose feed port is connected to the tower top discharge of the deweighting tower through a pipeline, and the material is roughly separated; a phenol recovery tower, whose feed port is connected to the tower top discharge of the coarse fractionation tower through a pipeline, and phenol is extracted from the tower top of the phenol recovery tower; the tower bottom material of the phenol recovery tower is refluxed to the coarse fractionation tower; and an acetophenone recovery tower, whose feed port is connected to the tower bottom discharge of the coarse fractionation tower through a pipeline, and acetophenone is extracted from the tower top of the acetophenone recovery tower; the tower bottom material of the acetophenone recovery tower is refluxed to the coarse fractionation tower. The system of the present invention reduces the harmful substances in tar to a relatively safe residual amount, achieves the goal of harmless treatment, and at the same time reduces the three wastes and improves the utilization value of tar.

Description

Technical Field

[0001] The invention belongs to the fields of coal chemical industry, petrochemical industry and environmental protection chemical industry, and specifically relates to a method for separating phenol and acetophenone from tar. Background Art

[0002] Phenol tar is included in the national hazardous waste list. Many companies do not have a good way to deal with it. Tar contains a lot of chemicals, such as phenol and acetophenone, which has a high recycling value and can be used in the fine chemical products industry. The treated tar can be used in oil refining equipment or incinerated for heat recovery, which can achieve significant economic benefits and has good environmental friendliness.

[0003] Patent CN108441250A discloses a phenol tar processing system and a processing method thereof, the system includes a phenol cutting tower and a coking unit, the bottom material outlet of the phenol cutting tower is connected to the coking unit, the invention adds a pretreatment device (i.e., a phenol cutting tower) on the basis of the existing coking method for treating phenol tar, separates phenol from the phenol tar, reduces the phenol in the tar to below 500 ppm, and solves the safety problems existing in the coking method for treating phenol tar, however, the phenol content is still high and corrosive.

[0004] Patent CN205076984U discloses a device for recovering useful substances from phenol tar. The device uses phenol tar, a by-product of the process of synthesizing phenol and acetone by the isopropylbenzene method in the petrochemical industry, as a raw material. Through the continuous operation of multiple distillation devices, the useful components phenol and acetophenone in the phenol tar are recovered. However, their separation effect on tar is still not ideal, and the purity of the product is not high. The patent uses up to 7 tower devices to achieve product separation, and its process is complicated and the investment cost is high. Summary of the invention

[0005] The purpose of the present invention is to provide a method for separating phenol and acetophenone from tar in order to solve the above problems. Through the pressure swing distillation method, the separation effect is improved, the purity of the product is guaranteed, the harmful substances in the tar can be removed, the three wastes are reduced, and the utilization value of the tar is improved.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A system for separating phenol and acetophenone from tar, comprising:

[0008] a de-weighting tower, used to remove heavy components from tar, wherein the heavy components of tar are extracted from the bottom of the de-weighting tower;

[0009] a coarse separation tower, whose feed port is connected to the top discharge of the deweighting tower through a pipeline to perform coarse separation on the materials;

[0010] a phenol recovery tower, whose feed port is connected to the top discharge of the crude fraction tower through a pipeline, and phenol is extracted from the top of the phenol recovery tower; the bottom material of the phenol recovery tower is refluxed to the crude fraction tower; and

[0011] An acetophenone recovery tower, whose feed port is connected to the bottom discharge of the crude fraction tower through a pipeline, and acetophenone is extracted from the top of the acetophenone recovery tower; the bottom material of the acetophenone recovery tower is refluxed to the crude fraction tower.

[0012] Furthermore, the system also includes a pretreatment unit, which is arranged at the front end of the de-weighting tower to pre-treat the tar entering the de-weighting tower. The pretreatment unit is a two-stage water washing and filtering system for removing impurities, and the feed is treated and separated to prevent impurities from entering the de-weighting tower.

[0013] Furthermore, the tops of the deweighting tower, crude fraction tower, phenol recovery tower and acetophenone recovery tower are all provided with condensers and reflux tanks, and the discharge from the top of the tower enters the reflux tank through the condenser, a part of the material refluxes into the tower, and the remaining material enters the next process.

[0014] Furthermore, the tower bottoms of the deweighting tower, the crude fraction tower, the phenol recovery tower and the acetophenone recovery tower are all provided with reboilers.

[0015] Furthermore, a preheater is provided in the feed pipeline of the deweighting tower, the crude fractionation tower, the phenol recovery tower and the acetophenone recovery tower.

[0016] Furthermore, the top operating pressure of the deweighting tower is 0.5 kPa(A) to 58 kPa(A), the top temperature is 130 to 220°C, and the bottom temperature is 160-330°C.

[0017] Furthermore, the top operating pressure of the crude fraction tower is 20 kPa (A) to 250 kPa (G), the top temperature is 130 to 220°C, and the bottom temperature is 160-250°C.

[0018] Furthermore, the top operating pressure of the phenol recovery tower is 5 kPa (A) to 68 kPa (G), the top temperature is 110 to 180°, and the bottom temperature is 150-220°C.

[0019] Furthermore, the top operating pressure of the acetophenone recovery tower is 0.5 kPa (A) to 8 kPa (G), the top temperature is 70 to 135°, and the bottom temperature is 110-175°C.

[0020] Since phenol and acetophenone are azeotropes, the tower pressure of each tower needs to be optimized to separate phenol and acetophenone more simply. The present invention adjusts the tower bottom reboiler temperature by controlling the tower pressure, thereby reducing the tower bottom reboiler temperature and lowering the steam grade requirement. At the same time, by lowering the temperature of the deweighting tower, the possibility of coking at the tower bottom is reduced, thereby optimizing the continuous operation of the tower.

[0021] Furthermore, the treated tar is heated to steam or hot oil after being incinerated in a hot oil furnace and supplied as a heat source for a reboiler or comprehensively utilized; the bottom discharge of the deweighting tower is used for preheating the tar feed; the bottom discharge of the coarse fractionation tower is used for preheating the coarse fractionation tower feed.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The system for separating phenol and acetophenone from tar provided by the present invention improves the separation effect and ensures the purity of the product through the pressure swing distillation method. Compared with CN108441250A, the phenol content can be reduced to below 100ppm after treatment in this patent, which can reduce the phenol content in the tar as much as possible, reduce corrosion, and further treat the tar to separate phenol and acetophenone products; compared with patent CN205076984U, the present invention is based on 4-tower separation, which is simpler than 7-tower separation, has a simpler process and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the tar purification system of the present invention;

[0025] In the figure: deweighting tower 1, crude fraction tower 2, phenol recovery tower 3, acetophenone recovery tower 4, condensers 5 / 6 / 7 / 8, reflux tanks 9 / 10 / 11 / 12, reboilers 13 / 14 / 15 / 16, and pretreatment unit 17. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example

[0028] like Figure 1A system for separating phenol and acetophenone from tar comprises: a deweighting tower 1 for removing heavy components from tar, and the bottom of the deweighting tower 1 produces heavy components of tar; a coarse fractionation tower 2, whose feed port is connected to the top discharge of the deweighting tower 1 through a pipeline, and performs coarse separation on the materials; a phenol recovery tower 3, whose feed port is connected to the top discharge of the coarse fractionation tower 2 through a pipeline, and phenol is produced from the top of the phenol recovery tower 3; the bottom materials of the phenol recovery tower 3 are refluxed to the coarse fractionation tower 2; and an acetophenone recovery tower 4, whose feed port is connected to the bottom discharge of the coarse fractionation tower 2 through a pipeline, and acetophenone is produced from the top of the acetophenone recovery tower 4; the bottom materials of the acetophenone recovery tower 4 are refluxed to the coarse fractionation tower 2.

[0029] The system also includes a pretreatment unit, which is arranged at the front end of the deweighting tower 1 to pretreat the tar entering the deweighting tower 1. The pretreatment unit is a two-stage water washing and filtering system for removing impurities. The feed is treated and separated to prevent impurities from entering the deweighting tower 1.

[0030] The tops of the de-weighting tower 1, the crude fraction tower 2, the phenol recovery tower 3 and the acetophenone recovery tower 4 are all provided with condensers and reflux tanks. The discharge from the top of the tower enters the reflux tank through the condenser, a part of the material refluxes into the tower, and the remaining material enters the next process. The bottoms of the de-weighting tower 1, the crude fraction tower 2, the phenol recovery tower 3 and the acetophenone recovery tower 4 are all provided with reboilers. The feed lines of the de-weighting tower 1, the crude fraction tower 2, the phenol recovery tower 3 and the acetophenone recovery tower 4 are provided with preheaters.

[0031] The top operating pressure of the deweighting tower 1 is 0.5 kPa (A) ~ 58 kPa (A), the top temperature is 130 ~ 220 ° C, and the bottom temperature is 160-330 ° C. The top operating pressure of the crude fraction tower 2 is 20 kPa (A) ~ 250 kPa (G), the top temperature is 130 ~ 220 ° C, and the bottom temperature is 160-250 ° C. The top operating pressure of the phenol recovery tower 3 is 5 kPa (A) ~ 68 kPa (G), the top temperature is 110 ~ 180 ° C, and the bottom temperature is 150-220 ° C. The top operating pressure of the acetophenone recovery tower 4 is 0.5 kPa (A) ~ 8 kPa (G), the top temperature is 70 ~ 135 ° C, and the bottom temperature is 110-175 ° C.

[0032] The treated tar is heated to steam or hot oil after being burned in a hot oil furnace and is supplied as a heat source for the reboiler or comprehensively utilized; the bottom discharge of deweighting tower 1 is used for preheating the tar feed; the bottom discharge of coarse fraction tower 2 is used for preheating the feed of coarse fraction tower 2.

[0033] The specific treatment process is as follows: the tar is treated by the pretreatment unit 17 and then enters the de-weighting tower. The top discharge of the de-weighting tower 1 is cooled by the condenser 5 and then enters the reflux tank 9, and then enters the coarse fraction tower 2. The bottom of the de-weighting tower 1 is provided with a heat source by the reboiler 13. The top discharge of the coarse fraction tower 2 is cooled by the condenser 6 and then enters the reflux tank 10, and then sent to the phenol recovery tower 3. The bottom of the coarse fraction tower 2 is provided with a heat source by the reboiler 14. The bottom discharge is sent to the acetophenone recovery tower 4. The top discharge of the acetophenone tower 4 is cooled by the condenser 8 and then enters the reflux tank 12, and is output as an acetophenone product. The bottom of the acetophenone tower 4 is provided with a heat source by the reboiler 16. The bottom discharge of the acetophenone tower 4 is sent to the coarse fraction tower 2. The top discharge of the phenol recovery tower 3 is cooled by the condenser 7 and then enters the reflux tank 11, as a phenol product. The bottom of the phenol recovery tower 3 is provided with a heat source by the reboiler 15. The bottom discharge of phenol recovery tower 3 is sent to the coarse fractionation tower.

[0034] This system takes the pilot test of phenol acetone tar treatment system as an example. The project aims to recover phenol and acetophenone. The purity of the recovered phenol and acetophenone can reach 99% (mass) and 95% (mass) respectively, which can initially meet the downstream market demand.

[0035] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for separating phenol and acetophenone from tar, characterized in that: The method uses a system for separating phenol and acetophenone from tar, and the system comprises: A deweighting tower (1) is used to remove heavy components from tar, and the tar heavy components are extracted from the bottom of the deweighting tower (1); a coarse separation tower (2), the feed inlet of which is connected to the top discharge of the deweighting tower (1) through a pipeline to perform coarse separation on the material; a phenol recovery tower (3), whose feed port is connected to the top discharge of the crude fraction tower (2) through a pipeline, and phenol is extracted from the top of the phenol recovery tower (3); the bottom material of the phenol recovery tower (3) is refluxed to the crude fraction tower (2), and the purity of the recovered phenol reaches more than 99%; and an acetophenone recovery tower (4), the feed port of which is connected to the bottom discharge of the crude fraction tower (2) through a pipeline, and acetophenone is extracted from the top of the acetophenone recovery tower (4); the bottom material of the acetophenone recovery tower (4) is refluxed to the crude fraction tower (2), and the purity of the recovered acetophenone reaches more than 95%; The deweighting tower (1) has a top operating pressure of 0.5 kPa(A) to 58 kPa(A), a top temperature of 130 to 220°C, and a bottom temperature of 160 to 330°C; The top operating pressure of the crude fraction tower (2) is 20 kPa (A) to 250 kPa (G), the top temperature is 130 to 220°C, and the bottom temperature is 160-250°C; The top operating pressure of the phenol recovery tower (3) is 5 kPa (A) to 68 kPa (G), the top temperature is 110 to 180°C, and the bottom temperature is 150-220°C; The system also includes a pre-processing unit (17); The tops of the deweighting tower (1), the crude fraction tower (2), the phenol recovery tower (3) and the acetophenone recovery tower (4) are all provided with a condenser and a reflux tank; The method comprises: The tar is treated in the pretreatment unit (17) and then enters the de-weighting tower. The top discharge of the de-weighting tower (1) is cooled in a condenser and then enters a reflux tank, and then enters a coarse fractionation tower (2). The top discharge of the crude fraction tower (2) is cooled by a condenser and then sent to a reflux tank, and then sent to a phenol recovery tower (3), and the bottom discharge is sent to an acetophenone recovery tower (4); The top discharge of the acetophenone tower (4) is cooled by a condenser and then enters a reflux tank to be output as an acetophenone product; the bottom discharge of the acetophenone tower (4) is sent to a coarse fractionation tower (2); The top discharge of the phenol recovery tower (3) is cooled by a condenser and then enters a reflux tank as a phenol product; the bottom discharge of the phenol recovery tower (3) is sent to a coarse fractionation tower (2).

2. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: The pretreatment unit is arranged at the front end of the deweighting tower (1) to pretreat the tar entering the deweighting tower (1).

3. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: The material discharged from the top of the tower enters the reflux tank through the condenser, a part of the material flows back into the tower, and the remaining material enters the next process.

4. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: The tower kettles of the deweighting tower (1), the crude fraction tower (2), the phenol recovery tower (3) and the acetophenone recovery tower (4) are all provided with reboilers.

5. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: Preheaters are provided in the feed pipelines of the deweighting tower (1), the crude fraction tower (2), the phenol recovery tower (3) and the acetophenone recovery tower (4).

6. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: The top operating pressure of the acetophenone recovery tower (4) is 0.5 kPa (A) to 8 kPa (G), the top temperature is 70 to 135°C, and the bottom temperature is 110-175°C.

7. A method for separating phenol and acetophenone from tar according to claim 1, characterized in that: The treated tar is burned in a hot oil furnace and then heated to steam or hot oil, which is then supplied as a heat source for a reboiler or used comprehensively; the bottom discharge of the deweighting tower (1) is used to preheat the tar feed; the bottom discharge of the coarse fractionation tower (2) is used to preheat the feed of the coarse fractionation tower (2).

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