CN110759804B - Device and method for extracting, rectifying and concentrating dimethylnaphthalene through lower side line - Google Patents

Abstract

The invention discloses a device for extracting, rectifying and concentrating dimethylnaphthalene on a lower side line, which comprises a rectifying tower and a recovery tower communicated with the rectifying tower; the rectifying tower comprises a first inlet for raw materials to enter, a second inlet for an extracting agent to enter, a first outlet arranged at the bottom end of the rectifying tower, a second outlet arranged at the top end of the rectifying tower and a third outlet arranged at the side edge of the rectifying tower; the recovery tower is provided with a third inlet communicated with the second outlet, a fourth outlet arranged at the top end of the recovery tower and communicated with the second inlet, and a fifth outlet arranged at the bottom end of the recovery tower. The device has simple structure, and the device can effectively save investment cost and reduce energy consumption by concentrating dimethylnaphthalene in the catalytic cracking light cycle oil LCO.

Description

A kind of device and method for concentrating dimethylnaphthalene by extraction, rectification of lower side line

technical field

The invention relates to a chemical extraction and rectification separation device and a separation method, in particular to a device and a method for concentrating dimethylnaphthalene by extraction, rectification and concentration of dimethylnaphthalene in a lower side line.

Background technique

The annual processing capacity of catalytic cracking (FCC) units in China exceeds 100 million tons, and the annual production of light cycle oil (LCO) exceeds 10 million tons. In the refining process, light cycle oil, as its name implies, is used as oil for circulation, and is generally not released. Catalytic cracked light cycle oil (LCO) varies with the cracking feedstock, cracking depth and cracking process, with extremely complex composition, wide distillation range, dark color and strong odor. At present, catalytic cracking light cycle oil (LCO) is mainly used in the following aspects: as diesel blending oil or directly as fuel oil; UOP's LCO Unicracking process adopts one-pass, one-pass, partially converted hydrocracking process , to produce ultra-low sulfur gasoline (ULSG) and ultra-low sulfur diesel (ULSD); the FD2G technology developed by Sinopec Fushun Petrochemical Research Institute uses LCO as raw material to produce high-octane (RON>90) gasoline fractions and sulfur mass fraction less than 10μg/g ultra-low-sulfur high-quality diesel oil with a cetane number that is 10-30 units higher than crude oil; RLG technology can use one-pass, integrated two-stage method, partial distillate circulation and other technological processes according to the nature of raw oil and product target requirements. , the technology includes the scheme of maximizing the production of gasoline and the production of xylene (BTX), and can also take into account the production of low-sulfur clean diesel blending components; the main processing purpose of the LCO-X process is to convert the materials in the range of petroleum naphtha into two by cracking. Toluene and benzene, while cracking the unconverted non-aromatics into LPG, the unconverted LCO mass fraction is less than 5%, the material from hydroprocessing conversion and aromatics maximization is carried out through the stripper and fractionator separation. It can be seen that the comprehensive utilization of catalytic cracking light cycle oil (LCO) has become the focus of deep processing of petrochemical enterprises, which will produce huge economic and environmental benefits, and will have a profound impact on the improvement and development of catalytic cracking (FCC) diesel production processes. .

The traditional production process mainly converts heavy aromatics into gasoline, diesel or BTX through catalytic cracking and disproportionation of circulating oil (LCO), which wastes the high value-added naphthalene compounds in LCO, especially methylnaphthalene and dimethylnaphthalene. Base naphthalene and dimethylnaphthalene have a variety of isomers, and the boiling point ranges from 262 °C to 270 °C. Among them, the boiling point of 2-ethylnaphthalene is 258 °C. Due to the small difference in boiling point, it is difficult to remove 2 by ordinary rectification. -Ethylnaphthalene. Currently reported dimethylnaphthalene concentration methods include cryogenic crystallization, extractive extraction/alkylation, cyclodehydrogenation and combination of extraction and rectification. The above method has problems such as complicated process or low purity and yield.

SUMMARY OF THE INVENTION

Purpose of the invention: The purpose of the present invention is to provide a device and method capable of effectively concentrating dimethylnaphthalene in LCO bicyclic aromatic hydrocarbons, and the content and yield of the concentrated dimethylnaphthalene are high.

Technical scheme: a device for concentrating dimethylnaphthalene by lower side-line extractive distillation according to the present invention comprises a rectifying tower and a recovery tower communicated with the rectifying tower;

The rectifying column comprises a first inlet for entering the raw material, a second inlet for entering the extractant, a first outlet arranged at the bottom of the rectifying column, and a second outlet arranged at the top of the rectifying column And the third outlet that is arranged on the side of the rectifying column;

The recovery tower is provided with a third inlet communicated with the second outlet, a fourth outlet at the top of the recovery tower communicated with the second inlet, and a fifth outlet at the bottom of the recovery tower.

The third outlet of the rectification tower is provided with a collection tank, a number of steam guide pipes and overflow pipes are distributed in the collection tank, and the air guide pipes and the overflow pipes are evenly distributed across, and the bottom of the collection tank is connected to the side line discharge. mouth.

Utilize the method for extracting, rectifying and concentrating dimethylnaphthalene of above-mentioned device, comprises the following steps:

(a) raw material enters rectifying tower from the first inlet of rectifying tower (1), feeds extraction agent from the second inlet, and the tower top bottom pressure of control rectifying tower is 0.005MPa and the tower bottom pressure of control rectifying tower is 0.010MPa, and the reflux ratio is 3 to 5:1;

(b) enter the extraction agent from the third inlet of the recovery tower, control the tower top pressure of the recovery tower to be 0.1 to 0.105MPa, the tower bottom pressure of the recovery tower (2) to be 0.105 to 0.115MPa, and the tower top temperature of the recovery tower to be 80.1 ~82.5℃, and the bottom temperature of the recovery tower is 253.2 ~ 255.6℃.

In step (a), the temperature at the top of the rectifying tower (1) is 93.4-95.8°C, the temperature at the side of the rectifying tower is 161.2-163.5°C, and the temperature at the bottom of the rectifying tower is 176.3-178.7°C.

In step (a), the plate extraction of the rectifying column is 90-110 pieces.

In step (a), the extractant is acetonitrile.

The first inlet is higher than the second inlet.

The height of the third outlet is lower than the height of the second inlet.

Beneficial effects: (1) the structure of the device of the present invention is simple, and the use of the device to concentrate dimethylnaphthalene in the catalytic cracking light cycle oil LCO can effectively save investment costs and reduce energy consumption; (2) the lower side line of the present invention is extracted, rectified and concentrated. The dimethylnaphthalene achieves the purpose of simplifying the separation process and simultaneously improving the purity and yield of the dimethylnaphthalene.

Description of drawings

Fig. 1 is the structural representation of the device of the lower side line extraction rectification concentrating dimethylnaphthalene in the present invention;

FIG. 2 is a schematic structural diagram of a collecting tank of the present invention.

Detailed ways

Embodiment 1: as shown in Figure 1, the device of the lower side-line extractive rectification concentrated dimethylnaphthalene of the present invention comprises a rectifying tower 1 and a recovery tower 2 communicated with the rectifying tower 1;

The rectification column 1 includes a first inlet 101 for entering raw materials, a second inlet 102 for entering an extractant, a first outlet 103 arranged at the bottom end of the rectification column 1, and a second outlet 104 arranged at the top of the rectification column 1 And the third outlet 105 arranged on the side of the rectifying tower 1, the first inlet 101 is higher than the height of the second inlet 102, the third outlet 105 is located in the middle and lower part of the rectifying tower 1, and the height of the third outlet 105 is low At the height of the second inlet 102, a collection tank 3 is provided at the third outlet 105 of the rectification tower 1. As shown in FIG. 2, a plurality of steam guide pipes 301 and overflow pipes 302 are distributed in the collection tank 3. The gas guide pipes 301 It is evenly distributed across the overflow pipe 302, and the bottom of the collecting tank 3 is connected to the side line outlet 303.

The recovery tower 2 is provided with a third inlet 201 connected to the second outlet 104 , a fourth outlet 202 connected to the second inlet 102 at the top of the recovery tower 2 , and a fifth outlet 203 at the bottom of the recovery tower 2 .

Utilize the method for extracting, rectifying and concentrating dimethyl by the device of embodiment 1, comprising the following steps:

(a) raw material enters rectifying tower 1 from the first inlet 101 of rectifying tower 1, feeds extraction agent from the second inlet 102, and controls the top and bottom pressure of rectifying tower 1 to be 0.005MPa and control the pressure of rectifying tower 1. The bottom pressure of the column is 0.010MPa, the plate extraction of the rectifying column 1 is 90～110 pieces, the reflux ratio is 3～5:1, the top temperature of the rectifying column 1 is 93.4～95.8 ℃, the side temperature of the rectifying column 1 is 93.4～95.8 ℃ It is 161.2～163.5 ℃, and the bottom temperature of rectifying tower 1 is 176.3～178.7 ℃;

(b) enter extractant acetonitrile from the third inlet 201 of recovery tower 2, the tower top pressure of control recovery tower 2 is 0.1～0.105MPa MPa, the bottom pressure of recovery tower 2 is 0.105～0.115MPa, the tower of recovery tower 2 The top temperature is 80.1-82.5°C, and the bottom temperature of the recovery tower 2 is 253.2-255.6°C. After the extraction agent is recovered by the recovery tower 2, it is sent to the rectification tower 1 from the fourth outlet 202.

Application example 1: take the residual fraction that the mass content of dimethylnaphthalene is 62.45%, the mass content of 2-ethylnaphthalene is 16.85%, and the mass content of trimethylnaphthalene is 5.99% as the raw material, from the upper part of the rectifying tower 1. The first inlet 101 enters the rectification tower 1 .

The first outlet 103 at the top of the rectifying tower 1 is a discharge port for 2-ethylnaphthalene and the above light components, and the second inlet 102 arranged in the middle of the rectifying tower 1 is used as the feed port of the extractant acetonitrile, and is set On the side of rectifying tower 1, the third outlet 105 located in the middle and lower part of rectifying tower 1 is a side line discharge section, and the bottom end of rectifying tower 1 is provided with the first outlet 103 that is used as the following heavy component of trimethylnaphthalene to send out, The bottom of the collection tank 3 is connected to the third outlet 105 of the side wire.

The top of the recovery tower is provided with the fourth outlet 202 used as the extraction agent acetonitrile discharge port, the middle is provided with the third inlet 201 for solvent recovery, and the bottom end is provided with the fifth outlet 203 for discharging heavy components such as 2-ethylnaphthalene;

The lower side line extractive distillation column 1 is used to further concentrate dimethylnaphthalene, a small amount of light components is discharged from the top of the lower side line extractive distillation column 1, and the high concentration dimethylnaphthalene is obtained from the lower side line discharge port, and the rectification column 1 is controlled. The top and bottom pressures of the column are 0.005MPa and 0.010MPa respectively, the top and bottom temperatures of the rectifying column 1 are 93.4-95.8℃ and 176.3-178.7℃, the side line temperature of the rectifying column 1 is 161.2-163.5℃, and the reflux ratio is 3:1 , Under the condition of stable operation, the content of dimethylnaphthalene in the side discharge of the lower side extraction distillation column 1 reaches 86.76%, and the yield reaches 95.72%.

The top and bottom pressures of solvent recovery tower 2 are controlled to be 0.1 MPa and 0.105 MPa, respectively, the top and bottom temperatures of recovery tower 2 are 80.1 to 82.5 °C and 253.2 to 255.6 °C, respectively, and the reflux ratio is 2. Recycling, under the condition of stable operation, the content of the extractant in the solvent recovery tower T2 reaches 99.98%, and the yield reaches 99.94%.

Table 1 Process conditions of separation process

The results of the concentrated dimethyl naphthalene in the catalytic cracking light cycle oil LCO of table 2

Application Example 2: Utilizing the device of Example 1, the remaining fractions with a mass content of dimethylnaphthalene of 62.45%, a mass content of 2-ethylnaphthalene of 16.85%, and a mass content of trimethylnaphthalene of 5.99% were used as raw materials. Rectifying tower 1 further concentrates dimethylnaphthalene, a small amount of light components is discharged from the top of rectifying tower 1, and the lower side line outlet obtains high-concentration dimethylnaphthalene, and the top and bottom pressures of rectifying tower 1 are controlled to be respectively: 0.005MPa and 0.010MPa, the top and bottom temperatures of rectifying column 1 are 93.4-95.8℃ and 176.3-178.7℃ respectively, the side line temperature of rectifying column 1 is 161.2-163.5℃, and the reflux ratio is 4:1, under the condition of stable operation , The content of dimethylnaphthalene in the rectification tower 1 side line discharge reaches 87.16%, and the yield reaches 96.21%. The top discharge of rectifying tower 1 is processed by recovery tower 2 for solvent recovery, the bottom fraction of recovery tower 2 is used as C10 solvent oil, and the extraction agent at the top of the tower can be recycled. Control the pressure at the top and bottom of recovery tower 2 to be 0.1 MPa and 0.105MPa, the top and bottom temperatures of the recovery tower 2 are 80.1 to 82.5 °C and 253.2 to 255.6 °C, respectively, the reflux ratio is 2, and the extractant in the discharge from the top of the recovery tower 2 is recycled. Under the condition of stable operation, The content of the extractant in the recovery tower 2 reaches 99.98%, and the yield reaches 99.94%.

Application example 3:

Utilize the device of embodiment 1, take the residual fraction that the mass content of dimethylnaphthalene is 62.45%, the mass content of 2-ethylnaphthalene is 16.85%, and the mass content of trimethylnaphthalene is 5.99% as raw materials, and the rectifying tower 1 is used to further Dimethyl naphthalene is concentrated, a small amount of light components is discharged from the top of rectifying tower 1, and high-concentration dimethyl naphthalene is obtained from the discharge port of the lower side line, and the top and bottom pressures of rectifying tower 1 are controlled to be 0.005MPa and 0.010MPa respectively. , the top and bottom temperatures of the tower are respectively 93.4～95.8℃ and 176.3～178.7℃, the side line temperature is 161.2～163.5℃, and the reflux ratio is 5:1. Under the condition of stable operation, in the rectification tower 1 side line discharge, dimethyl The content of naphthalene reaches 87.86%, and the yield reaches 96.75%. The top discharge of rectification tower 1 is processed by recovery tower 2, the bottom fraction of recovery tower 2 is used as C ₁₀ solvent oil, and the extraction agent at the top of the tower can be recycled. , The temperature at the top and bottom of the recovery tower 2 is 80.1～82.5℃ and 253.2～255.6℃ respectively, and the reflux ratio is 2. The extraction agent in the discharge at the top of the tower is recycled. Under the condition of stable operation, the extraction agent of the solvent recovery tower T2 The content reaches 99.98%, and the yield reaches 99.94%.

Claims (5)

1. a method for extracting and rectifying concentrated dimethylnaphthalene, is characterized in that, comprises the following steps: (a) The remaining fractions with a mass content of dimethylnaphthalene of 62.45%, a mass content of 2-ethylnaphthalene of 16.85%, and a mass content of trimethylnaphthalene of 5.99% are used as raw materials. The first inlet (101) that enters, the second inlet (102) for the extraction agent to enter, the first outlet (103) arranged at the bottom of the rectification column (1), and the first outlet (103) arranged at the rectification column (1) ) at the top of the second outlet (104) and the third outlet (105) at the side of the rectification tower (1); the raw material enters the rectification tower (101) from the first inlet (101) of the rectification tower (1). 1), feed the extraction agent from the second inlet (102), control the top and bottom pressure of the rectifying tower (1) to be 0.005MPa and control the bottom pressure of the rectifying tower (1) to be 0.010MPa, and the reflux ratio is 3 ~5:1; the column top temperature of the rectification column (1) is 93.4 ~ 95.8 ℃, the side line temperature of the rectification column (1) is 161.2 ~ 163.5 ℃, and the column bottom temperature of the rectification column (1) is 176.3 ~178.7°C; the extractant is acetonitrile; the rectification column (1) is a lower side-line extractive rectification column; (b) The recovery tower (2) is provided with a third inlet (201) in communication with the second outlet (104), and a third inlet (201) in communication with the second inlet (102) provided at the top of the recovery tower (2) The fourth outlet (202) and the fifth outlet (203) arranged at the bottom end of the recovery tower (2); enter the extractant from the third inlet (201) of the recovery tower (2) to control the tower of the recovery tower (2) The top pressure is 0.1~0.105MPa, the bottom pressure of the recovery tower (2) is 0.105~0.115MPa, the top temperature of the recovery tower (2) is 80.1~82.5℃, and the bottom temperature of the recovery tower (2) is 253.2~ 255.6°C. 2. The method for extracting, rectifying and concentrating dimethylnaphthalene according to claim 1, wherein the third outlet (105) of the rectifying tower (1) is provided with a collecting tank (3), and the A plurality of steam guide pipes (301) and overflow pipes (302) are distributed in the collection tank (3), and the air guide pipes and the overflow pipes are evenly distributed in cross, and the bottom of the collection tank (3) is connected to the side line outlet (303). The method for extracting, rectifying and concentrating dimethylnaphthalene according to claim 1, wherein in step (a), the number of theoretical plates of the rectifying tower (1) is 90-110. The method for extracting, rectifying and concentrating dimethylnaphthalene according to claim 2, characterized in that, the height of the first inlet (101) is higher than the height of the second inlet (102). The method for extracting, rectifying, and concentrating dimethylnaphthalene according to claim 2, characterized in that, the height of the third outlet (105) is lower than the height of the second inlet (102).

Images