Apparatus and method for recovering water washed toluene

Abstract

The present application relates to the field of toluene recovery, and discloses a device and method for recovering water-washed toluene. The device comprises a filter and a rectifying tower; the filter comprises a filter screen cylinder and two carbon steel pipes with lodestones at the ends and located at the central position of the filter screen cylinder; the rectifying tower comprises a feed inlet and side-line discharge outlets located at different sides of the feed inlet; and the feed inlet is located above the side-line discharge outlets. The filter can prevent solid particles and rust in the material from blocking the device. The feed inlet of the rectifying tower is located above the side-line discharge outlets and at different sides, and the on-line densimeter is located on the side wall of the reflux tank at the top of the rectifying tower. The volatile substances are intermittently collected at the top of the rectifying tower, the toluene is continuously collected from the side line of the rectifying tower, and the non-volatile substances are intermittently collected from the tower kettle. The process can effectively remove impurities such as hexane and chloroethane, reduce the content of toluene in the tower top distillate, reduce the discharge, and cause waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of toluene recovery, in particular to a device and method for recovering water-washed toluene. BACKGROUND

[0002] Toluene, as a main solvent and washing agent in the production of polyolefin catalyst, is involved in the whole process of catalyst synthesis. In the production process, toluene filtrate mixture is generated. In order to reduce the production cost, toluene in the toluene filtrate is recovered and utilized. The process steps of the recovery and utilization are as follows: toluene filtrate-crude toluene obtained by separation in a rectification tower-water-washed crude toluene-rectification tower for deep impurity removal-molecular sieve activation-qualified toluene.

[0003] In the process of water-washing crude toluene, a certain amount of titanium tetrachloride and hexane impurities are still contained in the crude toluene. The water-washing method is adopted to decompose the titanium tetrachloride. After the reaction, titanium dioxide solid particles are generated. The storage tank and the pressure pipeline for storing the water-washed toluene are made of carbon steel material. The carbon steel material is slowly oxidized to form rust when it is in contact with water. The solid particles and rust are mixed with the water-washed toluene and then enter the water-washed toluene rectification tower for deep impurity removal. The solid particles and rust can cause the blockage of the feed distributor of the water-washed toluene tower, increase the frequency of disassembling the tower, interfere with the feed flow meter, and cause the instability of the feed flow, thereby affecting the stability of the tower start-up and delaying the production.

[0004] The water-washed toluene rectification tower adopts conventional rectification technology for impurity removal, which has low recovery efficiency, causes a large amount of toluene to be discharged, increases the consumption of toluene, and increases the production cost of the catalyst.

[0005] Therefore, there is an urgent need for a new device and method for recovering toluene. SUMMARY

[0006] The present application aims to overcome the problems of the prior art, such as the complexity of the device for recovering water-washed toluene, the discharge of a large amount of toluene, and the blockage of the device caused by solid particles and rust, and provides a device and method for recovering water-washed toluene.

[0007] In order to achieve the above-mentioned purpose, the present application provides a device for recovering water-washed toluene, wherein the device comprises a filter and a rectification tower.

[0008] The filter comprises a filter screen cylinder and two carbon steel pipes with magnetite at the ends located at the center position of the filter screen cylinder.

[0009] The rectification tower comprises a feed inlet and a side-line discharge port located at different sides of the feed inlet.

[0010] The feed inlet is located above the side-line discharge port.

[0011] The second aspect of the present application provides a method for recycling water-washed toluene, wherein the method comprises recycling toluene from a material using the device for recycling water-washed toluene according to the first aspect of the present application, and the method comprises: feeding the material into a filter included in the device for filtration, feeding the filtered product into a rectifying column included in the device, intermittently collecting volatile substances from the top of the rectifying column, continuously collecting toluene from the side line of the rectifying column, and intermittently collecting non-volatile substances from the bottom of the rectifying column.

[0012] Through the above technical solutions, the present application achieves the following technical effects:

[0013] The filter includes a filter screen cylinder and two carbon steel pipes with magnetite at the ends, which are located at the center position of the filter screen cylinder, so that the solid particles and rust in the material can be prevented from blocking the device, the feed inlet of the rectifying column is located above the side line discharge port and at different sides, and the on-line densimeter is located on the side wall of the reflux tank at the top of the rectifying column, the volatile substances are intermittently collected from the top of the rectifying column, the toluene is continuously collected from the side line of the rectifying column, and the non-volatile substances are intermittently collected from the bottom of the rectifying column, so that the impurities such as hexane and chloroethane can be effectively removed, the content of toluene in the overhead distillate can be reduced, and the waste caused by discharge can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 FIG. 1 is a structural schematic diagram of the device for recycling water-washed toluene provided by the present application;

[0015] Figure 2 FIG. 2 is a structural schematic diagram of the filter in Example 1 provided by the present application.

[0016] REFERENCE NUMERALS

[0017] 1 feed tank 2 filter 3 rectifying column

[0018] 4 side line condenser 5 side line reflux tank 6 overhead condenser

[0019] 7 overhead reflux tank 8 on-line densimeter 9 reboiler

[0020] 10 filter screen 11 carbon steel pipe with magnetite DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical value, however, can include values up to and including the value of the lower limit, if stated, and values up to and including the value of the upper limit, if stated. Any numerical value, however, can include values up to and including the value of the lower limit, if stated, and values up to and including the value of the upper limit, if stated. For ranges including upper and lower limits, the range includes all values between the upper and lower limits. In some embodiments, the ranges of "from about lower limit / value to about upper limit / value" includes the value of the lower limit / value and the value of the upper limit / value. In some embodiments, the ranges of "from lower limit / value to upper limit / value" excludes the values of the lower limit / value and the value of the upper limit / value. The endpoints of all ranges and any values disclosed herein are included within the scope of the present application, unless specifically indicated otherwise. Any value, including any numerical value, can be combined with any other value, including any numerical value, to form a new value, unless otherwise indicated.

[0022] In order to achieve the above object, the present application provides a device for recycling water washing toluene, wherein the device comprises a filter and a rectifying tower;

[0023] The filter comprises a filter screen cylinder and two carbon steel pipes with magnetite at the ends and located at the central position of the filter screen cylinder.

[0024] The rectifying tower comprises a feeding port and side-line discharge ports located at different sides of the feeding port.

[0025] The feeding port is located above the side-line discharge ports.

[0026] In the present application, the filter comprises a filter screen cylinder and two carbon steel pipes with magnetite at the ends and located at the central position of the filter screen cylinder, which can prevent solid particles and rust in the material from blocking the device and avoid multiple disassembly and cleaning of the device.

[0027] In the present application, the feeding port of the rectifying tower is located above the side-line discharge ports and at different sides, and the material contains water, the boiling point of which is lower than that of toluene. Therefore, the side-line discharge ports are arranged below the feeding port to ensure that the water vapor is above the side-line discharge ports and the water content in the side-line discharged toluene is less than 50 ppm by mass.

[0028] According to the present application, a tower top reflux tank is arranged at the top of the rectifying tower, and an online densimeter is arranged on the side wall of the tower top reflux tank, which is used to measure the density of the liquid in the tower top reflux tank to reach 0.7-0.75 g / cm 3 , and the tower top discharge port of the rectifying tower is controlled.

[0029] In the present application, when the value of the online densimeter reaches 0.7-0.75 g / cm 3 , the tower top discharge of the rectifying tower is automatically opened, and when the discharge amount reaches 30%-50% of the tower top reflux tank, the automatic interlocking control is switched to manual mode, and the tower top discharge of the rectifying tower is closed to prevent a large amount of toluene from flowing out.

[0030] According to the present application, the feeding port is provided with a temperature controller for measuring and controlling the temperature of the feeding port to be 105-110°C, and the feeding port of the rectifying tower is located at the connection between the first tower section and the second tower section in the rectifying tower, and the temperature of the feeding port is the temperature of the second tower section.

[0031] According to the present application, the device further comprises a feeding tank 1, a tower top condenser 6, a tower top reflux tank 7, a side-line condenser 4, a side-line reflux tank 5 and a tower kettle reboiler 9.

[0032] According to the present application, the outlet of the feed tank is connected to the inlet of the filter, the outlet of the filter is connected to the feed inlet of the rectifying tower, the top of the rectifying tower is connected to the overhead condenser, the overhead condenser is connected to the overhead reflux tank, the side line outlet of the rectifying tower is connected to the side line condenser, the side line condenser is connected to the side line reflux tank, and the outlet of the tower kettle of the rectifying tower is connected to the tower kettle reboiler.

[0033] According to the present application, 3-5 tower sections are arranged in the rectifying tower.

[0034] The second aspect of the present application provides a method for recovering water-washed toluene, wherein the method comprises recovering toluene from a material using the device for recovering water-washed toluene according to the first aspect of the present application, and the method comprises: feeding the material into the filter included in the device for filtration, feeding the filtered product into the rectifying tower included in the device, intermittently collecting volatile substances from the top of the rectifying tower, continuously collecting toluene from the side line of the rectifying tower, and intermittently collecting non-volatile substances from the tower kettle of the rectifying tower.

[0035] In the present application, the volatile substances are intermittently collected from the top of the rectifying tower, toluene is continuously collected from the side line of the rectifying tower, and non-volatile substances are intermittently collected from the tower kettle of the rectifying tower, which can effectively remove impurities such as hexane and chloroethane, and reduce the water content of toluene and the content of toluene in the overhead distillate.

[0036] According to the present application, when the density of the liquid in the overhead reflux tank of the rectifying tower is 0.7-0.75 g / cm 3 , the overhead outlet of the rectifying tower is opened to discharge the volatile substances.

[0037] According to the present application, under the condition that the temperature of the tower kettle reboiler included in the device is 110-115 ℃, the filtered product is subjected to total reflux for 0.5-1 h, and when the temperature of the second tower section in the rectifying tower is 105-110 ℃, toluene is collected.

[0038] According to the present application, the material contains toluene, hexane, monochlorobutane, chlorohexane, trimethylheptane, and impurities.

[0039] According to the present application, based on the total weight of the material, the content of toluene is 90-98 wt%, the content of hexane is 2-7 wt%, the content of 1-chlorobutane is 0-1.5 wt%, the content of chloroethane is 0-0.5 wt%, the content of trimethylheptane is 0-0.5 wt%, and the content of the impurities is 0-0.5 wt%.

[0040] According to the present application, the impurities include titanium-containing substances and water.

[0041] According to the present application, the overhead conditions of the rectification tower include: temperature of 60-100℃, pressure of 2-5kPa.

[0042] The present application will be described in detail below through examples.

[0043] Example 1

[0044] The present application provides a method for recycling water-washed toluene. Figure 1 The device shown in the figure is used, Figure 2 The present application provides a structural diagram of a filter, and the specific operation method comprises:

[0045] The material is filtered through the filter screen 10 and the two end carbon steel pipes 11 with magnetite in the center position of the filter screen cylinder in the filter 2, and then enters the rectification tower 3 through the feed inlet, the overhead outlet and the tower kettle outlet are closed, the temperature of the tower kettle reboiler 9 is 113℃, the full reflux is 0.7h, the temperature of the second tower section in the rectification tower 3 is 107℃, the toluene is collected through the side line outlet, the side line condenser 4 and the side line reflux tank 5, and the volatile substances are collected through the overhead condenser 6 and the overhead reflux tank 7, when the value of the on-line densimeter 8 on the side wall of the overhead reflux tank 6 is 0.73g / cm 3 , the overhead collection of the rectification tower 3 is automatically opened, when the collection amount reaches 40% of the volume of the overhead reflux tank 7, the automatic interlocking control is switched to manual mode, the overhead collection of the rectification tower 3 is closed, and after the rectification tower 3 is closed, the tower kettle outlet is opened. Among them, the content of toluene is 94wt%, the content of hexane is 4.5wt%, the content of 1-chlorobutane is 0.75wt%, the content of chloroethane is 0.25wt%, the content of trimethylheptane is 0.25wt%, and the content of impurities is 0.25wt%, the temperature of the feed inlet is 107℃, the temperature of the overhead is 80℃, the pressure of the overhead is 3kPa, the content of toluene collected from the overhead is 19.53wt%, the content of hexane is 65.73wt%, the content of 1-chlorobutane is 7.42wt%, the content of chloroethane is 6.52wt%, the content of trimethylheptane is 0.65wt%, and the content of impurities is 0.15wt%, the content of toluene collected from the overhead is reduced by 79.2% compared with the content of toluene in the raw material.

[0046] Example 2

[0047] The present application provides a method for recycling water-washed toluene. Figure 1 The device shown in the figure is used, and the specific operation method comprises:

[0048] The material is filtered by the filter 2 through the filter screen 10 and the two carbon steel pipes 11 with the end of the filter screen tube center position with magnetite, and then enters the rectifying column 3 through the feed inlet, the overhead take-off and the column bottom take-off are closed, the temperature of the column bottom reboiler 9 is 110 DEG C, full reflux for 0.5h, the temperature of the second column section in the rectifying column 3 is 105 DEG C, the toluene is taken out through the side outlet, the side condenser 4 and the side reflux tank 5, the volatile substances are taken out through the overhead condenser 6 and the reflux tank 7, when the value of the on-line densimeter 8 on the side wall of the overhead reflux tank 6 is 0.7g / cm 3 , the overhead take-off of the rectifying column 3 is automatically opened, when the take-off amount reaches 30% of the volume of the overhead reflux tank 7, the automatic interlocking control is switched to the manual mode, the overhead take-off of the rectifying column 3 is closed, and the column bottom take-off is opened after the rectifying column 3 is closed, wherein the content of toluene in the material is 90wt%, the content of hexane is 7wt%, the content of 1-chlorobutane is 1.5wt%, the content of chloroethane is 0.5wt%, the content of trimethylheptane is 0.5wt% and the content of impurities is 0.5wt%, the temperature of the feed inlet is 105 DEG C, the temperature of the overhead is 60 DEG C, the pressure of the overhead is 2kPa, the content of toluene taken out from the overhead intermittently is 27.50wt%, the content of hexane is 56.82wt%, the content of 1-chlorobutane is 8.68wt%, the content of chloroethane is 5.78wt%, the content of trimethylheptane is 0.54wt% and the content of impurities is 0.68wt%, the content of toluene taken out from the overhead is reduced by 69.4% compared with the content of toluene in the raw material.

[0049] Example 3

[0050] The application provides a method for recycling water-washed toluene. Figure 1 The specific operation method comprises the following steps:

[0051] The material is filtered by the filter 2 through the filter screen 10 and the two carbon steel pipes 11 with the end of the filter screen tube center position with magnetite, and then enters the rectifying column 3 through the feed inlet, the overhead take-off and the column bottom take-off are closed, the temperature of the column bottom reboiler 9 is 115 DEG C, full reflux for 1h, the temperature of the second column section in the rectifying column 3 is 110 DEG C, the toluene is taken out through the side outlet, the side condenser 4 and the side reflux tank 5, the volatile substances are taken out through the overhead condenser 6 and the reflux tank 7, when the value of the on-line densimeter 8 on the side wall of the overhead reflux tank 6 is 0.75g / cm 3, the automatic opening of rectification tower 3 tower top, when the amount of 50% of the volume of tower top reflux tank 7, will automatically interlock control switch to manual mode, close the rectification tower 3 tower top, after closing the rectification tower 3, open the tower bottom outlet. Among them, the material is the content of toluene is 96wt%, the content of hexane is 2wt%, the content of 1-chlorobutane is 1wt%, the content of chloroethane is 0.3wt%, the content of trimethylheptane is 0.3wt% and the content of impurities is 0.4wt%, the temperature of the feed inlet is 110℃, the temperature of the tower top is 100℃, the pressure of the tower top is 5kPa, the content of toluene in the tower top intermittent extraction is 27.09wt%, the content of hexane is 62.35wt%, the content of 1-chlorobutane is 5.73wt%, the content of chloroethane is 3.82wt%, the content of trimethylheptane is 0.76wt% and the content of impurities is 0.25wt%, the content of toluene in the tower top extraction is reduced by 71.8% compared with the content of toluene in the raw material.

[0052] Comparative example 1

[0053] The present application provides a kind of conventional recovery water wash toluene method.The specific operation method includes:

[0054] Material is passed through feed tank 1 into filter 2 through filter screen 10 and the center position of filter screen tube two end carbon steel iron pipe 11 with magnetite filtering, then through feed inlet into rectification tower 3, tower top and side line continuous extraction, the reflux ratio of tower top is 1:1, after closing rectification tower 3, open tower bottom outlet. Among them, the material is the content of toluene is 94wt%, the content of hexane is 4.5wt%, the content of 1-chlorobutane is 0.75wt%, the content of chloroethane is 0.25wt%, the content of trimethylheptane is 0.25wt% and the content of impurities is 0.25wt%, the temperature of the feed inlet is 107℃, the temperature of the tower top is 80℃, the pressure of the tower top is 3kPa, the content of toluene in the tower top continuous extraction is 71.05wt%, the content of hexane is 20.85wt%, the content of 1-chlorobutane is 4.13wt%, the content of chloroethane is 2.68wt%, the content of trimethylheptane is 0.52wt% and the content of impurities is 0.77wt%, the content of toluene in the tower top extraction is reduced by 24.4% compared with the content of toluene in the raw material.

[0055] Comparative example 2

[0056] The present application provides a kind of conventional recovery water wash toluene method.The specific operation method includes:

[0057] The material is fed into the filter 2 through the feed tank 1, filtered by the filter screen 10 and the two carbon steel pipes 11 with magnetite at the end of the center of the filter screen cylinder, and then fed into the rectifying column 3 through the feed port, the overhead and side line are continuously taken out, the reflux ratio of the overhead is 1:2, the column is closed after the rectifying column 3, and the column bottom outlet is opened. Among them, the content of toluene in the material is 94wt%, the content of hexane is 4.5wt%, the content of 1-chlorobutane is 0.75wt%, the content of chloroethane is 0.25wt%, the content of trimethylheptane is 0.25wt%, and the content of impurities is 0.25wt%, the temperature of the feed port is 107℃, the temperature of the overhead is 80℃, the pressure of the overhead is 3kPa, the content of toluene taken out continuously from the overhead is 84.07wt%, the content of hexane is 11.18wt%, the content of 1-chlorobutane is 1.41wt%, the content of chloroethane is 2.84wt%, the content of trimethylheptane is 0.47wt%, and the content of impurities is 0.03wt%, the content of toluene taken out from the overhead is reduced by 10.6% compared with the content of toluene in the raw material.

[0058] As can be seen from Examples 1-3 and Comparative Examples 1-2, the content of toluene taken out from the overhead of Examples 1-3 is reduced by 79.2%, 69.4% and 71.8% respectively compared with the content of toluene in the raw material, and the content of toluene taken out from the overhead of Comparative Examples 1-2 is only reduced by 24.4% and 10.6% respectively compared with the content of toluene in the raw material, therefore, by using the method of the present application, the content of toluene in the overhead distillate can be reduced, and the waste caused by discharge can be reduced.

[0059] In summary, by using the method of the present application, the filter is provided with the filter screen cylinder and the two carbon steel pipes with magnetite at the end of the center, which can prevent the solid particles and rust in the material from blocking the device, the feed port of the rectifying column is located above the side line outlet and at different sides, and the online densitometer is provided on the side wall of the overhead reflux tank, and the volatile substances are intermittently taken out from the overhead of the rectifying column, toluene is continuously taken out from the side line of the rectifying column, and the non-volatile substances are intermittently taken out from the column bottom of the rectifying column, which can effectively remove the impurities such as hexane and chloroethane, and reduce the content of toluene in the overhead distillate.

[0060] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all belong to the protection scope of the present application.

Claims

1. A method of recovering water scrubbed toluene, characterized by, The method comprises: feeding the material into a filter of the device for filtration, feeding the filtered product into a rectifying column of the device, intermittently collecting volatile substances from the top of the rectifying column, continuously collecting toluene from the side line of the rectifying column, and intermittently collecting non-volatile substances from the bottom of the rectifying column. The filter comprises a filter screen cylinder and two carbon steel pipes with magnetite at the ends located at the center of the filter screen cylinder. The rectifying column comprises a feed inlet and a side line outlet located at different sides of the feed inlet. The feed inlet is located above the side line outlet.

2. The method of claim 1, wherein, The overhead of the rectifying tower is provided with an overhead reflux tank, a sidewall of the overhead reflux tank is provided with an online densimeter, which is used to determine the density of the liquid in the overhead reflux tank to reach 0.7-0.75 g / cm 3 When the density reaches 0.7-0.75 g / cm 3 , the overhead outlet of the rectifying tower is controlled.

3. The method of claim 1, wherein, The feed inlet is provided with a temperature controller for measuring and controlling the temperature of the feed inlet to be 105-110℃.

4. The method of claim 1, wherein, The device further comprises a feed tank, a top condenser, a top reflux tank, a side line condenser, a side line reflux tank, and a column bottom reboiler.

5. The method of claim 4, wherein, The outlet of the feed tank is connected to the inlet of the filter, the outlet of the filter is connected to the feed inlet of the rectifying column, the top of the rectifying column is connected to the top condenser, the top condenser is connected to the top reflux tank, the side line outlet of the rectifying column is connected to the side line condenser, the side line condenser is connected to the side line reflux tank, and the outlet of the bottom of the rectifying column is connected to the column bottom reboiler.

6. The method of claim 1, wherein, The interior of the rectifying column is provided with 3-5 column sections.

7. The method of claim 1, wherein, The process for intermittently taking off volatile substances from the top of the rectifying column includes: when the density of liquid in the top reflux tank of the rectifying column is 0.7-0.75 g / cm 3 , the top take-off outlet of the rectifying column is opened to discharge volatile substances.

8. The method of claim 1, wherein, The process of continuously collecting toluene from the side line of the rectifying column comprises: under the condition that the temperature of the column bottom reboiler included in the device is 110-115℃, the filtered product is subjected to total reflux for 0.5-1h, and when the temperature of the second column section in the rectifying column is 105-110℃, toluene is collected.

9. The method of claim 1, wherein, The material contains toluene, hexane, monochlorobutane, chloroethane, trimethylheptane, and impurities.

10. The method of claim 9, wherein, Based on the total weight of the material, the content of toluene is 90-98wt%, the content of hexane is 2-7wt%, the content of monochlorobutane is 0-1.5wt%, the content of chloroethane is 0-0.5wt%, the content of trimethylheptane is 0-0.5wt%, and the content of the impurities is 0-0.5wt%.

11. The method of claim 9, wherein, The impurities include titanium-containing substances and water.

12. The method of claim 1, wherein, The top conditions of the rectifying column include: temperature of 60-100℃ and pressure of 2-5kPa.

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