A system and method for extracting acetophenone from tar of pyrolysis of domestic waste

Abstract

The present application relates to the field of green environmental protection and resource utilization, and specifically discloses a system and method for extracting acetophenone from pyrolysis tar of domestic waste. The system includes a light component removal tower, a heavy component removal tower, and a pressure-swing distillation tower; the bottom discharge port of the light component removal tower is connected to the middle feed port of the heavy component removal tower, the top discharge port of the heavy component removal tower is connected to the middle feed port of the pressure-swing distillation tower, the top discharge port of the pressure-swing distillation tower is connected to the upper feed port of the heavy component removal tower, the bottom discharge port of the pressure-swing distillation tower is connected to the lower feed port of the heavy component removal tower, and the upper part of the pressure-swing distillation tower is connected to a pressure control device. Realize resource utilization of domestic waste. In the process, the pyrolysis tar has been separated into light and heavy components to achieve preliminary refining of the pyrolysis tar. The light component is a takeaway product after decolorization and deodorization. The heavy component can be secondary pyrolyzed or burned for heat supply. Improve the value of pyrolysis tar and realize resource utilization of domestic waste.

Description

Technical Field

[0001] The invention belongs to the technical field of green environmental protection and resource utilization, and relates to a system and method for extracting acetophenone from tar produced by pyrolysis of domestic waste. Background Art

[0002] With the improvement of the technical standards for the treatment of domestic waste in my country, the defects of the three traditional methods of domestic waste treatment, namely landfill, composting and incineration, are increasingly highlighted. The development of domestic waste pyrolysis technology with low secondary pollution, complete harmlessness and high degree of resource utilization has become a hot topic of research. While achieving the harmlessness, reduction and resource utilization of waste, the pyrolysis technology of domestic waste can effectively overcome the problem of dioxin pollution caused by incineration, so it has become an emerging treatment technology with great development prospects. Pyrolysis is an oxygen-deficient decomposition process, and the tar components produced are mainly olefins and aromatic hydrocarbons, which have high utilization value. However, the tar produced by the pyrolysis process is generally returned to the pyrolysis furnace as a fuel and used as a heat source, which seriously underestimates the value of pyrolysis oil and causes waste of resources. Therefore, extracting acetophenone with high content and easy purification from the pyrolysis tar of domestic waste can greatly improve the economy of the waste pyrolysis process, improve the resource utilization of domestic waste, and enhance the competitiveness of waste pyrolysis treatment enterprises.

[0003] At present, the methods for producing acetophenone in China mainly include: direct plant extraction, acylation reaction of benzene, ethylbenzene oxidation reaction, purification of phenol tar produced as a byproduct of cumene oxidation, and bioconversion. Therefore, the method of using garbage pyrolysis tar to purify acetophenone has opened up a new direction for the production of acetophenone.

[0004] With the continuous deepening of environmental protection concepts and the continuous improvement of people's material living standards, how to treat domestic waste in a harmless, resource-based and reduced manner has become a focus of attention. The above methods have low purification accuracy and low efficiency. Therefore, the distillation-pressure swing separation method is used to treat pyrolysis tar, which can efficiently extract high-value-added, high-purity acetophenone, which plays an important role in the development of the waste treatment industry. Summary of the invention

[0005] In order to solve the problem of resource waste caused by using domestic waste pyrolysis oil as fuel to a certain extent, the present application proposes a system and method for extracting acetophenone from domestic waste pyrolysis tar, and to perform high-value treatment on the waste pyrolysis oil, so as to improve the economy of the domestic waste pyrolysis treatment process and improve the resource utilization of domestic waste.

[0006] This application adopts the following technical solutions:

[0007] A system for extracting acetophenone from tar of pyrolysis of domestic waste comprises a light component removal tower, a heavy component removal tower and a pressure-swing distillation tower; a bottom discharge port of the light component removal tower is connected with a middle feed port of the heavy component removal tower, a top discharge port of the heavy component removal tower is connected with a middle feed port of the pressure-swing distillation tower, a top discharge port of the pressure-swing distillation tower is connected with an upper feed port of the heavy component removal tower, a bottom discharge port of the pressure-swing distillation tower is connected with a lower feed port of the heavy component removal tower, and the upper part of the pressure-swing distillation tower is connected with a vacuum device.

[0008] The bottom of the light component removal tower is connected to a first reboiler for adjusting the temperature in the tower, and the top of the light component removal tower is connected to a first condenser for condensation. The bottom of the heavy component removal tower is connected to a second reboiler for adjusting the temperature in the tower, and the top of the heavy component removal tower is connected to a second condenser for condensation. The bottom of the pressure swing distillation tower is connected to a third reboiler for adjusting the temperature in the tower, and the top of the pressure swing distillation tower is connected to a third condenser for condensation.

[0009] A first conveying pipe is connected between the bottom discharge port of the light component removal tower and the middle feed port of the heavy component removal tower, a first reboiler is arranged on the first conveying pipe, and a first reboiler reflux pipe is connected between the first reboiler and the light component removal tower; a second discharge pipe is connected to the bottom of the heavy component removal tower, a second reboiler is arranged on the second discharge pipe, and a second reboiler reflux pipe is connected between the second reboiler and the bottom of the heavy component removal tower; a third bottom discharge pipe is arranged at the bottom discharge port of the pressure swing distillation tower, the third bottom discharge pipe is connected to the third reboiler, and a third reboiler reflux pipe is connected between the third reboiler and the bottom of the pressure swing distillation tower.

[0010] The top discharge port of the light component removal tower is connected with a first discharge pipe, a first condensation reflux pipe is connected between the first discharge pipe and the top of the light component removal tower, and a first condenser is arranged on the first cooling reflux pipe; a second conveying pipe is connected between the top discharge port of the heavy component removal tower and the middle feed port of the pressure swing distillation tower, a second condensation reflux pipe is connected between the second conveying pipe and the top of the heavy component removal tower, and a second condenser is arranged on the second condensation reflux pipe; a third top discharge pipe is arranged at the top discharge port of the pressure swing distillation tower, a third top discharge pipe is connected between the third top discharge pipe and the top of the pressure swing distillation tower, and a third condenser is arranged on the third condensation reflux pipe.

[0011] A second stream pipe is connected between the third tower bottom discharge pipe and the lower feed inlet of the heavy component removal tower; a first stream pipe is connected between the third tower top discharge pipe and the upper feed inlet of the heavy component removal tower.

[0012] The first circulating stream flows from the third tower top outlet through the first stream pipe into the upper feed port of the deheaving component tower; the second circulating stream flows from the third tower bottom outlet through the second stream pipe into the lower feed port of the deheaving component tower.

[0013] The vacuum device is connected to the third tower top discharge pipe and the third tower top discharge pipe through a vacuum pipe, and the vacuum device includes a vacuum pump and a regulating valve arranged on the vacuum pipe, and the vacuum pump outlet is connected to the regulating valve inlet. The size of the regulating valve opening is used to adjust the exhaust gas extraction amount of the system, thereby adjusting the vacuum degree of the tower.

[0014] The light component removal tower, heavy component removal tower and pressure swing distillation tower are all provided with a tower plate assembly, the tower plate assembly includes a sieve plate and a cylinder, the cylinder is vertical and passes through the sieve plate and is connected to the middle of the sieve plate, a plurality of sieve holes are provided on the sieve plate, a filler is provided in the cylinder, an overflow portion and a baffle are provided on the sieve plate, at least two through grooves along the radial direction of the sieve plate are provided on the sieve plate, the overflow portion is connected to one side of the through groove and gradually extends downwardly until it extends to the bottom position on the other side of the through groove, and the baffle is fixedly connected to the upper surface of the sieve plate and is located on the side of the through groove relative to the connection position of the overflow portion.

[0015] Along the radial direction of the screen plate, the middle part of the bottom of the overflow portion is concave downward in an arc shape.

[0016] The gas inside the pressure swing distillation tower passes through the sieve holes and fillers on the sieve plate from bottom to top. A certain liquid level is left on the sieve plate. The liquid flows to the next tower plate through the overflow part and then passes through the next tower plate assembly.

[0017] The overflow part is made into a dustpan shape, which can effectively increase the gas-liquid contact area and flow rate of the overflow part. As well as the "plate-filling combination" form of the pedal assembly, both changes increase the gas-liquid mass transfer area and rate to a certain extent, and increase the separation efficiency of the distillation tower.

[0018] A method for extracting acetophenone from tar produced by pyrolysis of domestic waste comprises the following steps:

[0019] (1) The tar is sent to a light component removal tower, and the light component is discharged. The bottom material of the light component removal tower is a heavy component, an azeotropic component acetophenone and phenol. The bottom material of the light component removal tower is sent to a heavy component removal tower;

[0020] (2) The azeotropic component is distilled from the top of the heavy component removal tower and then enters the pressure swing distillation tower, and the heavy component is extracted from the bottom of the heavy component removal tower;

[0021] (3) The pressure swing distillation tower alternately operates in a low-pressure separation state and a high-pressure separation state;

[0022] The low-pressure separation state is: 110°C, 0.05 bar, the first circulating stream between the top discharge port of the pressure swing distillation tower and the upper feed port of the deheaving component tower is opened, the second circulating stream between the bottom discharge port of the pressure swing distillation tower and the lower feed port of the deheaving component tower is closed, and acetophenone is produced from the bottom discharge port of the pressure swing distillation tower;

[0023] The high-pressure separation state is: the first circulating stream between the top discharge port of the pressure swing distillation tower at 200°C and 1.01 bar and the upper feed port of the deheaving component tower is closed, the second circulating stream between the bottom discharge port of the pressure swing distillation tower and the lower feed port of the deheaving component tower is opened, and phenol is produced from the top discharge port of the pressure swing distillation tower;

[0024] When the purity (molar fraction) of phenol extracted from the third condenser (3a) drops to 98%, switch the pipeline of the pressure-swing distillation tower, close the second circulating stream, and open the first circulating stream. Adjust the operating pressure of the pressure-swing distillation tower from 1.00-1.01 bar to 0.04-0.05 bar, and lower the temperature from 200-210°C to 110-120°C, and extract acetophenone in the third reboiler (3b). When the acetophenone concentration (molar fraction) drops to 99%, close the first circulating stream and open the second circulating stream. At the same time, adjust the temperature to 200-210°C and the pressure to 1.00-1.01 bar to extract phenol.

[0025] Specifically, take the pyrolysis tar of domestic waste as an example:

[0026] Light component removal: In the light component removal tower, light components are extracted from the top of the tower. The components are named with acetophenone and phenol as the dividing points to define light and heavy components. Components with boiling points lower than acetophenone and phenol are light components, and components with boiling points higher than acetophenone and phenol are heavy components. At this time, the temperature of the first reboiler is adjusted according to the different contents of various substances in the pyrolysis tar. The specific conditions are normal pressure and 200-210℃. The light component oil is of good quality and can be used directly or sold after decolorization and deodorization.

[0027] Removal of heavy components: The heavy components in the tower kettle of the light component removal tower, the azeotropic components acetophenone and phenol enter the heavy component removal tower, where the heavy components are extracted from the bottom of the heavy component removal tower, and the heavy components can be subjected to secondary pyrolysis or combustion for heat supply. At this time, the azeotropic components acetophenone and phenol are distilled from the top of the heavy component removal tower and enter the pressure swing distillation tower.

[0028] Pressure swing distillation: The pressure swing distillation tower can change the pressure in the tower body through a vacuum device, so that the pressure swing distillation tower can switch between the high-pressure distillation tower and the low-pressure distillation tower, and at the same time, the temperature in the pressure swing distillation tower can be adjusted through the third reboiler.

[0029] When the azeotropic component enters the pressure-swing distillation tower, the pressure-swing distillation tower is first transformed into a low-pressure distillation tower using a vacuum device. After passing through the low-pressure distillation tower, most of the high-purity acetophenone can be separated, and part of the acetophenone, phenol azeotrope and phenol are circulated back to the de-heavy component tower through the first circulating stream; when the purity (molar fraction) of the distilled acetophenone drops to 99%, the pressure-swing distillation tower is changed to a high-pressure distillation tower and the distillation temperature is changed. At this time, it is necessary to collect the top distillate component phenol, and at the same time close the first circulating stream and open the second circulating stream, so that acetophenone and acetophenone, phenol azeotrope all enter the de-heavy component tower after circulation. The first circulating stream 1 and the second circulating stream are used alternately, and acetophenone and phenol are extracted alternately. This process can simplify the azeotropic separation process. This azeotropic component separation equipment can be designed for separation components with complex components and low component content such as pyrolysis tar.

[0030] Furthermore, the heavy component removal tower realizes the cyclic distillation of the first circulating stream and the second circulating stream in the pressure swing distillation tower by setting different feed positions, thereby ensuring the continuous operation of the entire system.

[0031] The pressure-swing distillation tower realizes the integration of low-pressure distillation tower and high-pressure distillation tower into one, and realizes the pressure-swing distillation operation of a single tower by changing the operating parameters.

[0032] Furthermore, the first condenser, the second condenser and the third condenser are partition-type heat exchangers.

[0033] Furthermore, in the vacuum device, the outlet of the vacuum pump is connected to the inlet of the regulating valve. The opening of the regulating valve is used to adjust the exhaust gas extraction amount of the system, thereby adjusting the vacuum degree of the tower.

[0034] In summary, this application at least includes the following beneficial technical effects:

[0035] (1) The three towers have continuous feeding and discharging, and can be scaled up.

[0036] (2) Maximize the use of useful components in the by-product tar after pyrolysis of domestic waste to realize resource utilization of domestic waste. In the process, the pyrolysis tar has been separated into light and heavy components to achieve the initial refining of the pyrolysis tar. The light component is the takeaway product after decolorization and deodorization. The heavy component can be pyrolyzed again or burned for heat. The value of pyrolysis tar is increased to realize the resource utilization of domestic waste.

[0037] (3) This method is a new method for preparing acetophenone, which has low cost and high product purity, and the molar fraction of acetophenone can be as high as 99% or more. At the same time, high-purity by-product phenol is produced, and the molar purity of phenol is as high as 98% or more.

[0038] (4) The pressure swing distillation tower used in the present method is a multifunctional distillation tower with adjustable temperature and pressure, which integrates two traditional distillation towers. This allows the azeotropic components to be separated and collected separately in one tower, thus reducing energy consumption.

[0039] (5) The tower plates are in the form of a "plate-fill combination" and the overflow portion is in the shape of a dustpan, which increases the gas-liquid mass transfer area and rate to a certain extent and increases the separation efficiency of the distillation tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic flow chart of a system and method for extracting acetophenone from tar from pyrolysis of domestic waste in an embodiment of the present application;

[0041] Figure 2 A schematic diagram of the structure of a tray assembly in an embodiment of the present application.

[0042] Description of reference numerals: 1. light component removal tower; 2. heavy component removal tower; 3. pressure swing distillation tower; 4. vacuum device; 41. vacuum pump; 42. regulating valve;

[0043] 1a, first condenser; 1b, first reboiler; 2a, second condenser; 2b, second reboiler; 3a, third condenser; 3b, third reboiler;

[0044] a. Filler; b. Overflow; c. Sieve plate; d. Sieve hole; e. Baffle. DETAILED DESCRIPTION

[0045] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0046] The embodiments of the present application disclose a system and method for extracting acetophenone from tar produced by pyrolysis of domestic waste.

[0047] A system for extracting acetophenone from tar produced by pyrolysis of domestic waste, such as Figure 1 As shown, it includes a light component removal tower 1, a heavy component removal tower 2, and a pressure swing distillation tower 3; the bottom discharge port of the light component removal tower 1 is connected with the middle feed port of the heavy component removal tower 2, the top discharge port of the heavy component removal tower 2 is connected with the middle feed port of the pressure swing distillation tower 3, the top discharge port of the pressure swing distillation tower 3 is connected with the upper feed port of the heavy component removal tower 2, the bottom discharge port of the pressure swing distillation tower 3 is connected with the lower feed port of the heavy component removal tower 2, and the upper part of the pressure swing distillation tower 3 is connected with a pressure control device.

[0048] A first conveying pipe is connected between the bottom discharge port of the light component removal tower 1 and the bottom discharge port of the light component removal tower 1, a first reboiler 1b is arranged on the first conveying pipe, and a first reboiler 1b is connected to the light component removal tower 1; a first discharge pipe is connected to the top discharge port of the light component removal tower 1, a first condensation reflux pipe is connected between the first discharge pipe and the top of the light component removal tower 1, and a first condenser 1a is arranged on the first cooling reflux pipe. A second discharge pipe is connected to the bottom of the heavy component removal tower 2, a second reboiler 2b is arranged on the second discharge pipe, and a second reboiler 2b is connected to the bottom of the heavy component removal tower 2; a second conveying pipe is connected between the top discharge port of the heavy component removal tower 2 and the middle feed port of the pressure swing distillation tower 3, a second condensation reflux pipe is connected between the second conveying pipe and the top of the heavy component removal tower 2, and a second condenser 2a is arranged on the second condensation reflux pipe. A third bottom discharge pipe is provided at the bottom discharge port of the pressure-swing distillation tower 3, the third bottom discharge pipe is connected to the third reboiler 3b, and a third reboiler reflux pipe is connected between the third reboiler 3b and the bottom of the pressure-swing distillation tower 3; a third top discharge pipe is provided at the top discharge port of the pressure-swing distillation tower 3, a third condensation reflux pipe is connected between the third top discharge pipe and the top of the pressure-swing distillation tower 3, and the third condensation reflux pipe is provided with a third condenser 3a.

[0049] A second stream pipe is connected between the third tower bottom discharge pipe and the lower feed port of the de-heavy component tower 2; a first stream pipe is connected between the third tower top discharge pipe and the upper feed port of the de-heavy component tower 2. The first circulating stream flows from the third tower top discharge port through the first stream pipe into the upper feed port of the de-heavy component tower 2; and the second circulating stream flows from the third tower bottom discharge port through the second stream pipe into the lower feed port of the de-heavy component tower 2.

[0050] The vacuum device 4 is a vacuum pump. The regulating valve of the vacuum device 4 is installed on the reflux pipeline of the vacuum pump. The opening of the regulating valve is used to adjust the exhaust gas extraction amount of the system, thereby adjusting the vacuum degree of the tower.

[0051] A plate assembly is arranged inside the pressure-swing distillation tower 3. The plate assembly includes a sieve plate c and a cylinder. The cylinder is vertical and penetrates the sieve plate c and is connected to the middle of the sieve plate c. A plurality of sieve holes d are provided on the sieve plate c. A filler a is provided inside the cylinder. An overflow portion b and a baffle e are provided on the sieve plate c. At least two through grooves along the radial direction of the sieve plate c are provided on the sieve plate c. The overflow portion b is connected to one side of the through groove and gradually extends downward in an inclined manner until it extends to the bottom position of the other side of the through groove. The baffle e is fixedly connected to the upper surface of the sieve plate c and is located on one side of the through groove relative to the connection position of the overflow portion b. Along the radial direction of the sieve plate c, the middle part of the bottom of the overflow portion b is arc-shaped and concave downward, forming a dustpan shape. In this embodiment, two through grooves are provided, and the two through grooves are evenly distributed around the axis of the sieve plate c.

[0052] This embodiment also discloses a method for extracting acetophenone from pyrolysis tar of domestic waste. Taking pyrolysis tar of domestic waste as an example, the parameters of pyrolysis tar of domestic waste are as follows:

[0053]

[0054] The following steps are involved:

[0055] (1) 4.12 L / h of pyrolysis tar is pumped into the light component removal tower 1. The first reboiler 1b is maintained at a temperature of 203°C and normal pressure. As the reaction proceeds, the light components in the pyrolysis tar are extracted from the first condenser 1a at the top of the tower.

[0056] (2) Subsequently, the heavy components at the bottom of the light component removal tower 1 and phenol and acetophenone are pumped into the heavy component removal tower 2, and the second reboiler 2b is maintained at a temperature of 250°C and normal pressure. In the heavy component removal tower 2, the azeotropic components can be completely separated from the pyrolysis tar, and the light components and the heavy components are also simply separated in this process. The boiling point of the light components is below 250°C and has a high use value; the heavy components can re-enter the pyrolysis reactor for secondary pyrolysis or combustion for heat supply.

[0057] (3) The azeotropic components extracted from the second condenser 2a at the top of the heavy component removal tower 2 enter the pressure swing distillation tower 3. After pipeline switching and adjustment of operating conditions, a high-purity phenol solution of 5.6 mol / h can be extracted from the third condenser 3a at the top of the pressure swing distillation tower 3, and a high-purity acetophenone solution of 9.721 mol / h can be extracted from the third reboiler 3b at the bottom of the tower. The remaining azeotropic substances enter the heavy component removal tower 2 again for circulation separation.

[0058] The pressure-swing distillation tower 3 is divided into two situations: a high-pressure distillation tower and a low-pressure distillation tower. When the azeotropic components enter the pressure-swing distillation tower 3, the temperature is first adjusted by the third reboiler 3b and the pressure is adjusted by the vacuum device 4 so that the pressure-swing distillation tower 3 becomes a low-pressure distillation tower. The temperature of the pressure-swing distillation tower 3 is 110°C and the pressure is 0.05 bar during the low-pressure process. At this time, the first circulating stream is in the open state and the second circulating stream is closed. In this process, acetophenone is mainly separated from pyrolysis tar and taken out from the bottom outlet of the pressure swing distillation tower 3. Part of acetophenone, phenol azeotrope and phenol enter the heavy component removal tower 2 from the upper part of the heavy component removal tower 2 through the first circulating stream. Phenol gradually accumulates in this circulation process. When the molar concentration of acetophenone drops to 99%, the pressure swing distillation tower 3 is switched to become a high-pressure distillation tower. The high-pressure process temperature of the pressure swing distillation tower 3 is 200° C. and the pressure is 1.01 bar. At this time, the first circulating stream is closed and the second circulating stream is opened. Phenol, a distillate component of the third condenser 3a at the top of the tower, is collected. Through the second circulating stream, acetophenone and the azeotrope of acetophenone and phenol all enter the heavy component removal tower 2 from the lower part of the tower.

[0059] When the molar concentration of phenol in the second circulating stream drops to 98%, switch the pipeline of the pressure-swing distillation tower, close the second circulating stream, and open the first circulating stream. Adjust the operating pressure of the pressure-swing distillation tower from 1.01 bar to 0.05 bar, and the temperature from 210°C to 120°C, so that acetophenone is extracted in the third reboiler 3b, and phenol enters the circulation, and the pipeline switching and the operating pressure and temperature of the pressure-swing distillation tower 3 are performed by analogy. This process can simplify the azeotropic separation process. This azeotropic component separation equipment is designed for separation components such as pyrolysis tar, which has complex components and low component content.

[0060] The isolated products were tested as follows:

[0061] The purity of the products phenol and acetophenone was detected by gas chromatography-mass spectrometry.

[0062] The yield and purity of acetophenone and phenol in the pyrolysis tar of domestic waste are as follows:

[0063] Yield / (%) Purity / (mole fraction) Acetophenone >95 99.6 phenol >95 99

[0064] For pyrolysis tar, a substance to be separated with complex ingredients, low content of ingredients and azeotropic components, the traditional pressure swing separation is changed from two distillation towers (high-pressure tower and low-pressure tower) to a variable-pressure separation tower. Only the temperature and pressure of the tower body need to be adjusted to achieve the conversion of the separated substances. At this time, not only high-purity and high-value acetophenone can be separated, but also high-purity by-product phenol solution can be separated. The pyrolysis tar is simply refined so that the light and heavy components can be separated with acetophenone and phenol as the boundary. The light components can be directly sold or used as fuel oil after decolorization, deodorization and other processes. The heavy components are re-entered into the pyrolysis furnace for secondary pyrolysis or combustion for heat supply.

[0065] The above is a preferred embodiment of the present invention. It should be pointed out that in this field, many technicians can make other extraction schemes through appropriate deformation and improvement on the basis of the present invention. These deformation and improved schemes should also be regarded as the protection scope of the invention.

Claims

1. A system for extracting acetophenone from tar from pyrolysis of domestic waste, characterized in that: It comprises a light component removal tower (1), a heavy component removal tower (2), and a pressure swing distillation tower (3); The bottom discharge port of the light component removal tower (1) is connected to the middle feed port of the heavy component removal tower (2), the top discharge port of the heavy component removal tower (2) is connected to the middle feed port of the pressure swing distillation tower (3), the top discharge port of the pressure swing distillation tower (3) is connected to the upper feed port of the heavy component removal tower (2), the bottom discharge port of the pressure swing distillation tower (3) is connected to the lower feed port of the heavy component removal tower (2), and the upper part of the pressure swing distillation tower (3) is connected to a vacuum device (4) for adjusting the pressure in the pressure swing distillation tower (3); The light component removal tower (1), the heavy component removal tower (2) and the pressure swing distillation tower (3) are all provided with a tower plate assembly, the tower plate assembly comprising a sieve plate (c) and a cylinder, the cylinder is vertical and penetrates the sieve plate (c) and is connected to the middle of the sieve plate (c), a plurality of sieve holes (d) are provided on the sieve plate (c), a filler (a) is provided in the cylinder, an overflow portion (b) and a baffle (e) are provided on the sieve plate (c), at least two through grooves along the radial direction of the sieve plate (c) are provided on the sieve plate (c), the overflow portion (b) is connected to one side of the through groove and gradually extends downwardly in an inclined manner until it extends to the bottom position of the other side of the through groove, and the baffle (e) is fixedly connected to the upper surface of the sieve plate (c) and is located on the side of the through groove relative to the connection position of the overflow portion (b).

2. The system for extracting acetophenone from pyrolysis tar of domestic waste according to claim 1, characterized in that: A first conveying pipe is connected between the bottom discharge port of the light component removal tower (1) and the middle feed port of the heavy component removal tower (2), a first reboiler (1b) is arranged on the first conveying pipe, and a first reboiler (1b) is connected to the light component removal tower (1); a second discharge pipe is connected to the bottom of the heavy component removal tower (2), a second reboiler (2b) is arranged on the second discharge pipe, and a second reboiler (2b) is connected to the bottom of the heavy component removal tower (2); a third bottom discharge pipe is arranged at the bottom discharge port of the pressure-swing distillation tower (3), the third bottom discharge pipe is connected to a third reboiler (3b), and a third reboiler (3b) is connected to the bottom of the pressure-swing distillation tower (3).

3. The system for extracting acetophenone from pyrolysis tar of domestic waste according to claim 1, characterized in that: The top discharge port of the light component removal tower (1) is connected to a first discharge pipe, a first condensation reflux pipe is connected between the first discharge pipe and the top of the light component removal tower (1), and a first condenser (1a) is arranged on the first cooling reflux pipe; a second conveying pipe is connected between the top discharge port of the heavy component removal tower (2) and the middle feed port of the pressure-swing distillation tower (3), a second condensation reflux pipe is connected between the second conveying pipe and the top of the heavy component removal tower (2), and a second condenser (2a) is arranged on the second condensation reflux pipe; a third top discharge pipe is arranged at the top discharge port of the pressure-swing distillation tower (3), a third condensation reflux pipe is connected between the third top discharge pipe and the top of the pressure-swing distillation tower (3), and a third condenser (3a) is arranged on the third condensation reflux pipe.

4. The system for extracting acetophenone from pyrolysis tar of domestic waste according to claim 2, characterized in that: A second stream pipe is connected between the third tower bottom discharge pipe and the lower feed inlet of the heavy component removal tower (2); and a first stream pipe is connected between the third tower top discharge pipe and the upper feed inlet of the heavy component removal tower (2).

5. The system for extracting acetophenone from pyrolysis tar of domestic waste according to claim 1, characterized in that: The vacuum device (4) is connected to the third tower top discharge pipe and the third tower top discharge pipe through a vacuum pipe, and the vacuum device (4) comprises a vacuum pump (41) and a regulating valve (42) arranged on the vacuum pipe, and the outlet of the vacuum pump (41) is connected to the inlet of the regulating valve (42).

6. The system for extracting acetophenone from pyrolysis tar of domestic waste according to claim 1, characterized in that: Along the radial direction of the sieve plate (c), the middle part of the bottom of the overflow portion (b) is concave downward in an arc shape.

7. A method for extracting acetophenone from tar from pyrolysis of domestic waste, characterized in that: A system for extracting acetophenone from tar from pyrolysis of domestic waste according to any one of claims 1 to 6 comprises the following steps: (1) The tar is fed into a light component removal tower (1), and the light component is discharged. The bottom material of the light component removal tower (1) is a heavy component and azeotropic components acetophenone and phenol. The bottom material of the light component removal tower (1) is fed into a heavy component removal tower (2); (2) The azeotropic component is distilled from the top of the heavy component removal tower (2) and enters the pressure swing distillation tower (3), and the heavy component is extracted from the bottom of the heavy component removal tower (2); (3) The pressure swing distillation tower (3) alternately performs a low-pressure separation state and a high-pressure separation state; The low-pressure separation state is: the first circulating stream between the top discharge port of the pressure swing distillation tower (3) and the upper feed port of the heavy component removal tower (2) is opened, the second circulating stream between the bottom discharge port of the pressure swing distillation tower (3) and the lower feed port of the heavy component removal tower (2) is closed, and acetophenone is produced from the bottom discharge port of the pressure swing distillation tower (3); The high-pressure separation state is: the first circulating stream between the top discharge port of the pressure-swing distillation tower (3) and the upper feed port of the heavy component removal tower (2) is closed, the second circulating stream between the bottom discharge port of the pressure-swing distillation tower (3) and the lower feed port of the heavy component removal tower (2) is opened, and phenol is produced from the top discharge port of the pressure-swing distillation tower (3); (4) When the purity of phenol extracted from the top outlet of the pressure swing distillation tower (3) drops to 98%, the high-pressure separation state is switched to the low-pressure separation state; when the purity of acetophenone extracted from the bottom outlet of the pressure swing distillation tower (3) drops to 99%, the low-pressure separation state is switched to the high-pressure separation state.

8. The method for extracting acetophenone from pyrolysis tar of domestic waste according to claim 7, characterized in that: The low-pressure separation state is: 110-120°C, 0.04-0.05 bar; the high-pressure separation state is: 200-210°C, 1.00-1.01 bar.

9. The method for extracting acetophenone from pyrolysis tar of domestic waste according to claim 7, characterized in that: In the step (1), the temperature in the light component removal tower (1) is 200-210° C. and normal pressure; in the step (2), the temperature in the heavy component removal tower (2) is 240-250° C. and normal pressure.

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