Tail gas treatment system of PETG (polyethylene terephthalate glycol) device

Abstract

The utility model discloses a tail gas treatment system of a PETG (polyethylene terephthalate glycol) device, which is characterized in that an outlet of a tail gas pipe of the PETG device is connected with a gas inlet of a cyclone separator, a top exhaust port of the cyclone separator is connected with an inlet of an induced draft fan, an outlet of the induced draft fan is connected with a gas inlet of an alkali liquor neutralization tank, and an exhaust port of the alkali liquor neutralization tank is connected with a gas inlet at the lower part of a tail gas leaching tower; an annular gas distribution pipe communicated with the gas inlet is arranged in a liquid phase space at the lower part of the tail gas leaching tower; a plurality of coil gas outlet holes are uniformly distributed at the lower half part of the annular gas distribution pipe; a plurality of filler layers are arranged along the height direction of the tail gas leaching tower, a spraying device is arranged above each filler layer, and a sieve plate is arranged below each filler layer outside the bottom layer; a gas outlet in the top of the tail gas leaching tower is connected with a gas inlet of an activated carbon adsorption tank; an exhaust port of the activated carbon adsorption tank is communicated with the atmosphere through an exhaust fan. The system is low in water consumption, low in activated carbon replacement frequency and capable of ensuring that tail gas can be discharged after reaching the standard.

Description

Technical Field

[0001] The utility model relates to a PETG production device, in particular to a tail gas treatment system for a PETG device, belonging to the technical field of tail gas treatment equipment. Background Art

[0002] PETG is a transparent plastic and an amorphous copolyester. Its full name is polyethylene terephthalate-1,4-cyclohexanedimethanol (CHDM). PETG's commonly used comonomer is 1,4-cyclohexanedimethanol (CHDM). PETG is made from three monomers: terephthalic acid (PTA) or isophthalic acid (IPA), ethylene glycol (EG), and neopentyl glycol (NPG) (or 1,4-cyclohexanedimethanol CHDM). Using an antimony compound or titanium catalyst, it undergoes direct esterification followed by polycondensation. PETG sheet offers high light transmittance, a high-gloss surface, excellent chemical resistance, high impact strength, and is environmentally friendly and non-toxic. It is widely used in industries such as advertising, machinery, food, and packaging. It can be used in medical equipment, advertising signs, high-transparency price tags, machine covers, baffles, observation windows, and photo frames.

[0003] PETG production equipment generates tail gas from equipment such as the slurry mixing system, heat trap, vacuum system, esterification and polycondensation reactors. The main components of the tail gas include acetaldehyde, ethylene glycol, neopentyl glycol (NPG), water vapor, air, dust and solids. The conventional PET tail gas leaching system collects the tail gas through a pipeline, separates the deposited liquid or dust through a cyclone separator, and then enters a conventional leaching tower for water washing to remove water-soluble media in the tail gas.

[0004] The traditional PET plant tail gas treatment system has the following problems: 1. The water consumption of the leaching tower is large, which increases the wastewater treatment load, and the impurity content of the tail gas after treatment is still high;

[0005] 2. The exhaust gas after leaching usually cannot meet the environmental emission standards and can only be processed or burned. The emission of combustion products affects the air quality. Some manufacturers will add activated carbon collection tanks and then discharge them. Since the exhaust gas entering the activated carbon tank exceeds the standard seriously, the activated carbon needs to be replaced frequently, which increases maintenance and use costs.

[0006] 3. In addition to the same exhaust gas components as the PET device, the PETG device also produces an additional NPG component, which has a melting point of 124~130℃ and is easy to crystallize and adhere to the inner wall of the equipment during the exhaust gas treatment process. Utility Model Content

[0007] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and utility model title of this application, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0008] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0009] The purpose of the utility model is to overcome the problems existing in the prior art and provide a PETG device tail gas treatment system to reduce the consumption of rinsing water, improve the spray washing effect, reduce the cost of activated carbon replacement, and ensure that the PETG tail gas can meet the emission standards.

[0010] To solve the above technical problems, the utility model provides a PETG device tail gas treatment system, including a PETG device tail gas pipe, the outlet of the PETG device tail gas pipe is connected to the air inlet of a cyclone separator, the top exhaust port of the cyclone separator is connected to the inlet of an induced draft fan, the outlet of the induced draft fan is connected to the air inlet of an alkali solution neutralization tank, the exhaust port of the alkali solution neutralization tank is connected to the air inlet of a lower part of a tail gas scrubbing tower, an annular air distribution pipe connected to the air inlet is provided in the lower liquid phase space of the tail gas scrubbing tower, and a plurality of coil air outlet holes are evenly distributed on the lower half of the annular air distribution pipe; a plurality of packing layers are provided along the height direction of the tail gas scrubbing tower, a spray device is provided above each packing layer, and a sieve plate is provided below each packing layer other than the bottom layer; the air outlet at the top of the tail gas scrubbing tower is connected to the air inlet of an activated carbon adsorption tank, and the exhaust port of the activated carbon adsorption tank is communicated with the atmosphere or connected to a combustion furnace through an exhaust fan.

[0011] As an improvement of the present invention, a dust removal inner cylinder is provided along the center line of the cyclone separator, the upper end of the dust removal inner cylinder is connected below the top wall of the cyclone separator, and a chilled water coil is provided in the annular space between the dust removal inner cylinder and the inner wall of the cyclone separator cylinder.

[0012] As a further improvement of the present invention, two or more cyclone separators are installed in parallel, and the outer periphery of the cyclone separator is covered with a cooling jacket. The bottom interface of the cooling jacket is connected to the chilled water supply pipe and the condensed water outlet pipe, and the upper interface of the cooling jacket is connected to the chilled water return pipe and the steam inlet pipe.

[0013] As a further improvement of the present invention, the air inlet of the alkali liquid neutralization tank is connected to the alkali washing air inlet pipe through a check valve, the lower end of the alkali washing air inlet pipe extends below the liquid level of the alkali liquid neutralization tank, and the top inlet of the alkali liquid neutralization tank is connected to the bottom outlet of the alkali liquid preparation tank.

[0014] As a further improvement of the present invention, the bottom drain outlet of the tail gas scrubbing tower is connected to the inlet of the wastewater circulation pump, the outlet pipe of the wastewater circulation pump is connected to the hot side inlet of the scrubbing cooler, the hot side outlet of the scrubbing cooler is connected to the spray main pipe, and the spray main pipe is connected to the inlet of the spray device on each layer through the spray branch pipe, and the inlet of the spray device on the top layer is also connected to the clean water pipe.

[0015] As a further improvement of the present invention, each spray branch pipe is further connected to the compressed air deblocking pipe and the air extraction deblocking pipe respectively through a switching valve.

[0016] As a further improvement of the present invention, each screen plate is provided with a plurality of diamond-shaped holes, and a diamond-shaped umbrella cap is provided above each diamond hole. The two corners of the bottom surface of each diamond-shaped umbrella cap are symmetrically connected with downwardly extending umbrella cap support feet, and the lower end of each umbrella cap support foot is bent outward to limit the maximum flying height of the diamond-shaped umbrella cap.

[0017] As a further improvement of the present invention, the area of ​​each diamond-shaped umbrella cap is larger than the diamond-shaped hole below, and the corners of each diamond-shaped hole are symmetrically provided with limiting protrusions that are higher than the plane of the screen plate.

[0018] As a further improvement of the present invention, the top surface of each diamond-shaped umbrella cap is in a cone shape with a high center and low surrounding areas.

[0019] As a further improvement of the present invention, the diameter of the air outlet holes of each coil is 6-8 mm.

[0020] Compared with the existing technology, the utility model has achieved the following beneficial effects: 1. The cyclone separator is added with a jacket, which is connected to cooling water and steam. Normal cooling water cools the exhaust gas and removes part of the condensate. If NPG crystals adhere to the inner wall and block the equipment, the standby unit can be switched during production, and then the cooling water in the jacket of this unit is switched to steam heating to melt and remove the NPG, thereby ensuring the normal operation of production.

[0021] 2. Before entering the leaching tower, the exhaust gas enters the alkali neutralization tank to neutralize the acidic medium. After neutralization, the gas enters the exhaust leaching tower, and the salt generated in the alkali tank enters the sewage treatment device. This not only reduces the amount of water sprayed in the leaching tower and alleviates the load on the leaching tower, but also prevents the exhaust acid from entering the sewage treatment device and reacting with wastewater from other devices throughout the plant to produce hazardous substances.

[0022] 3. Improve the elution effect of the elution tower. Set a gas redistribution coil in the air inlet and open 6~8mm air holes in the lower half of the coil to allow the gas to enter the tower evenly and the elution is more thorough.

[0023] 4. To increase the contact area and residence time between the elution water and the tail gas, diamond-shaped sieve plate holes are set at the bottom of the upper and middle packing layers, and a diamond-shaped umbrella cap with a raised center is set in each hole to facilitate the gas and liquid to be evenly distributed again at the sieve plate, thereby increasing the gas-liquid contact area and time.

[0024] 5. Improve the effect of the elution nozzle. The elution nozzle will be blocked after long-term use. Adding blowing and suction facilities to the elution pipe can successfully eliminate the blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. The drawings are only provided for reference and explanation, and are not intended to limit the present invention. Among them:

[0026] Figure 1 This is a flow chart of the tail gas treatment system of the PETG device of the utility model;

[0027] Figure 2 This is a top view of the sieve plate in the tail gas scrubbing tower;

[0028] Figure 3 It is a partial cross-sectional view of the sieve plate;

[0029] Figure 4 This is a top view of the annular gas distribution pipe in the tail gas scrubbing tower;

[0030] Figure 5 It is a partial view of the annular gas distribution pipe;

[0031] In the figure: 1. Cyclone separator; 1a. Cooling jacket; 1b. Dust removal inner cylinder; 1c. Chilled water coil; 2. Induced draft fan; 3. Alkali solution preparation tank; 4. Alkali solution neutralization tank;

[0032] 5. Tail gas scrubber; 5a. Annular air distribution pipe; 5a1. Coil outlet; 5b. Packing layer; 5c. Sieve plate; 5c1. Diamond-shaped holes; 5c2. Diamond-shaped cap; 5c3. Cap support foot; 5c4. Stopper protrusion;

[0033] 6. Wastewater circulation pump; 7. Leaching cooler; 8. Switching valve; 9. Activated carbon adsorption tank; 10. Exhaust fan; 11. Automatic regulating valve; 12. Sewage treatment station;

[0034] FT. Flow meter; TG. Thermometer; LT. Liquid level gauge;

[0035] G1. PETG unit tail gas pipe; G2. Chilled water supply pipe; G3. Chilled water return pipe; G4. Steam inlet pipe; G5. Condensate outlet pipe; G6. Cyclone separation liquid phase outflow pipe; G7. Cooling water supply pipe; G8. Cooling water return pipe; G9. Clean water pipe; G10. Compressed air deblocking pipe; G11. Exhaust deblocking pipe; G12. Jumper pipe. DETAILED DESCRIPTION

[0036] In the following description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0037] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only a part of the present invention, not all of the embodiments.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] like Figures 1 to 5 As shown, the PETG device tail gas treatment system of the present invention includes a cyclone separator 1, an induced draft fan 2, an alkali solution preparation tank 3, an alkali solution neutralization tank 4, a tail gas elution tower 5, a wastewater circulation pump 6, an elution cooler 7, a switching valve 8, an activated carbon adsorption tank 9 and an exhaust fan 10. The outlet of the PETG device tail gas pipe G1 is connected to the air inlet of the cyclone separator 1, the top exhaust port of the cyclone separator 1 is connected to the inlet of the induced draft fan 2, the outlet of the induced draft fan 2 is connected to the alkali washing air inlet pipe, the alkali washing air inlet pipe is connected to the air inlet of the alkali solution neutralization tank 4 through a check valve, the lower end of the alkali washing air inlet pipe extends below the liquid level of the alkali solution neutralization tank 4, and the top inlet of the alkali solution neutralization tank 4 is connected to the bottom outlet of the alkali solution preparation tank 3.

[0040] The exhaust port of the alkali solution neutralization tank 4 is connected to the air inlet at the bottom of the tail gas washing tower 5, and the air outlet at the top of the tail gas washing tower 5 is connected to the air inlet of the activated carbon adsorption tank 9. The exhaust port of the activated carbon adsorption tank 9 is connected to the atmosphere through the exhaust fan 10 or is connected to the combustion furnace.

[0041] A dust removal inner cylinder 1b is provided along the center line of the cyclone separator 1. The upper end of the dust removal inner cylinder 1b is connected to the bottom of the top wall of the cyclone separator 1. A chilled water coil 1c is provided in the annular space between the dust removal inner cylinder 1b and the inner wall of the cyclone separator 1. The chilled water supply pipe G2 is connected to the inlet of the chilled water coil 1c, and the outlet of the chilled water coil 1c is connected to the chilled water return pipe G3.

[0042] Two or more cyclone separators 1 are installed in parallel. The outer periphery of each cyclone separator 1 is covered with a cooling jacket 1a. The bottom connection of the cooling jacket 1a is connected to the chilled water supply pipe G2 and the condensed water outlet pipe G5. The upper connection of the cooling jacket 1a is connected to the chilled water return pipe G3 and the steam inlet pipe G4. During operation, chilled water from the chilled water supply pipe G2 enters the lower part of the cooling jacket 1a, fills the cooling jacket 1a, and then flows out of the upper connection and back to the refrigeration station through the chilled water return pipe G3.

[0043] Exhaust gas from the PETG unit's tailpipe G1, primarily containing acetaldehyde, ethylene glycol, neopentyl glycol, water vapor, air, and dust solids, enters cyclone separator 1, where it rotates downward in the annular space surrounding the dust removal inner cylinder 1b. Centrifugal force removes some liquid and dust solids while cooling the exhaust gas. The cooled gas then enters the inner cavity of dust removal inner cylinder 1b and is discharged through the gas phase outlet at the top center of cyclone separator 1. Liquid and dust collected at the bottom of cyclone separator 1 are discharged through cyclone liquid phase outlet pipe G6 and sent to sewage treatment station 12 for treatment.

[0044] After a period of operation, NPG crystals will form on the inner wall of cyclone separator 1. At this point, the cyclone separator is switched to standby mode. The valve on steam inlet pipe G4 is opened, allowing fresh steam to enter cooling jacket 1a for indirect heating, melting and removing the NPG. The steam then exchanges heat to form condensate, which is then discharged through condensate outlet pipe G5 for recycling. This ensures long-term, continuous and normal production operation.

[0045] After cyclone dust removal and cooling, exhaust gas is pressurized by induced draft fan 2 and enters alkali neutralization tank 4 to neutralize the acidic medium. After the alkali is consumed, it is replenished by alkali preparation tank 3. The bottom outlet of alkali neutralization tank 4 is connected to sewage treatment station 12 via a sewage pipe. The upper overflow port of alkali neutralization tank 4 is connected to the sewage pipe through a sight glass, allowing the salt generated in alkali neutralization tank 4 to enter sewage treatment station 12 for treatment. This reduces water consumption and load in exhaust scrubber 5; it also prevents acidic substances in the exhaust gas from entering sewage treatment station 12 and reacting with wastewater from other equipment throughout the plant to produce hazardous substances.

[0046] An annular air distribution pipe 5a, connected to the air inlet, is located in the lower liquid phase of the tail gas scrubber 5. The pipe can be formed by two semicircular shapes connected by flanges. Multiple coil outlet holes 5a1 are evenly distributed in the lower half of the pipe, each with a diameter of 6-8 mm. Multiple packing layers 5b are arranged along the height of the tail gas scrubber 5, each with a spray device located above it.

[0047] The bottom drain outlet of the tail gas scrubber 5 is connected to the inlet of a wastewater circulation pump 6. The outlet pipe of the wastewater circulation pump 6 is connected to the hot-side inlet of the scrubber cooler 7. The hot-side outlet of the scrubber cooler 7 is connected to the spray main pipe, which is connected to the inlet of each layer of the spray device via spray branches. The cold-side inlet of the scrubber cooler 7 is connected to the chilled water supply pipe G2 or the cooling water supply pipe G7, and the cold-side outlet of the scrubber cooler 7 is connected to the chilled water return pipe G3 or the cooling water return pipe G8.

[0048] In the tail gas scrubber 5, each packing layer 5b, except the bottom layer, is equipped with a sieve plate 5c. Each sieve plate 5c is uniformly distributed with multiple diamond-shaped holes 5c1. Above each diamond-shaped hole 5c1, a diamond-shaped cap 5c2 is installed. The top surface of each diamond-shaped cap 5c2 is conical, with a high center and low edges, to facilitate the dripping of water droplets. Downward-extending cap support legs 5c3 are symmetrically connected to the two corners of the bottom surface of each diamond-shaped cap 5c2. The lower end of each cap support leg 5c3 is bent outward.

[0049] Driven by the airflow from below, each diamond-shaped umbrella cap 5c2 floats upward until the bent portion of the umbrella cap support leg 5c3 rests against the bottom of the sieve plate 5c. At this time, the diamond-shaped umbrella cap 5c2 reaches its maximum flying height, and the exhaust gas is blown out from the diamond-shaped hole 5c1 and the surrounding areas of the diamond-shaped umbrella cap 5c2.

[0050] Each diamond-shaped cap 5c2 has a larger area than the diamond-shaped hole 5c1 below it. Each diamond-shaped hole 5c1 has symmetrically positioned stopper protrusions 5c4 at its corners, rising above the plane of the sieve plate 5c. When the wind pressure below is low, the diamond-shaped cap 5c2 falls above the stopper protrusion 5c4, creating a minimum gap between the cap 5c2 and the diamond-shaped hole 5c1, preventing water from clogging the sieve plate 5c. This creates a thick water film on the sieve plate 5c, ensuring that water falls along the edge of each diamond-shaped hole 5c1, achieving secondary uniform water distribution. Exhaust gas flows through each diamond-shaped hole 5c1, ensuring uniform rinsing.

[0051] After being neutralized in the alkali neutralization tank 4, the gas enters the annular gas distribution pipe 5a of the tail gas scrubber 5 and is discharged through the coiled outlet holes 5a1 at the bottom of the annular gas distribution pipe 5a, ensuring that the tail gas is distributed as evenly as possible across the tower cross-section. It first comes into contact with water to remove impurities. The tail gas then flows upward through three packing layers 5b, where it fully contacts the liquid water sprayed from above. Water-soluble media enter the water and are removed. The wastewater circulation pump 6 at the bottom of the tower sends the spray water to the scrubber cooler 7. After cooling on the cold side, it is then sent through the spray main pipe to the various spray branches. From these branches, it enters the spray devices on each layer and is sprayed downward. A thermometer TG is installed on the spray main pipe to monitor the circulating water temperature.

[0052] The clean water pipe G9 is connected to the inlet of the top layer spraying device through a valve and a flow meter FT. The top layer can be sprayed with tap water or other relatively clean recycled water to improve the cleanliness of the exhaust gas. Fresh water can also be added and the packing layer 5b can be cleaned.

[0053] A liquid level gauge LT is installed on the side wall of the liquid collecting hopper at the bottom of the tail gas scrubbing tower 5. The outlet of the wastewater circulation pump 6 is also connected to the sewage treatment station 12 through a sewage pipe and an automatic regulating valve 11. The opening of the automatic regulating valve 11 is controlled by the liquid level in the tail gas scrubbing tower 5.

[0054] The wastewater circulation pump 6 sends the washing wastewater to the sewage treatment station 12 for treatment. The gas discharged from the top of the tail gas washing tower 5 enters the activated carbon adsorption tank 9 to remove the remaining medium, and finally meets the air emission standards and can be discharged directly.

[0055] In special cases, the tail gas discharged from the alkali solution neutralization tank 4 can directly enter the activated carbon adsorption tank 9 through the jumper pipe G12 for impurity removal. If the tail gas does not meet the emission standards, it can be sent to the combustion furnace for incineration.

[0056] After running for a long time, the rinse nozzle will be clogged. By changing the direction of the switching valve 8, compressed air can be injected from the compressed air declogging pipe G10, or suction can be performed through the exhaust declogging pipe G11. By alternating these steps, the blockage of the nozzles can be successfully eliminated one by one.

[0057] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation methods without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A PETG device tail gas treatment system, comprising a PETG device tail gas pipe, characterized in that: The outlet of the tail gas pipe of the PETG device is connected to the air inlet of the cyclone separator, the top exhaust port of the cyclone separator is connected to the inlet of the induced draft fan, the outlet of the induced draft fan is connected to the air inlet of the alkali solution neutralization tank, and the exhaust port of the alkali solution neutralization tank is connected to the air inlet at the bottom of the tail gas elution tower. An annular air distribution pipe connected to the air inlet is provided in the lower liquid phase space of the tail gas scrubbing tower, and a plurality of coil air outlet holes are evenly distributed on the lower half of the annular air distribution pipe; a plurality of packing layers are provided along the height direction of the tail gas scrubbing tower, a spray device is provided above each packing layer, and a sieve plate is provided below each packing layer other than the bottom layer; The air outlet at the top of the tail gas washing tower is connected to the air inlet of the activated carbon adsorption tank, and the exhaust port of the activated carbon adsorption tank is connected to the atmosphere through an exhaust fan.

2. The PETG device tail gas treatment system according to claim 1, wherein: A dust removal inner cylinder is provided along the center line of the cyclone separator. The upper end of the dust removal inner cylinder is connected below the top wall of the cyclone separator. A chilled water coil is provided in the annular space between the dust removal inner cylinder and the inner wall of the cyclone separator cylinder.

3. The PETG device tail gas treatment system according to claim 1, wherein: Two or more cyclone separators are installed in parallel. The outer periphery of the cyclone separator is covered with a cooling jacket. The bottom interface of the cooling jacket is connected to the chilled water supply pipe and the condensed water outlet pipe, and the upper interface of the cooling jacket is connected to the chilled water return pipe and the steam inlet pipe.

4. The PETG device tail gas treatment system according to claim 1, wherein: The air inlet of the alkali liquid neutralization tank is connected to the alkali washing air inlet pipe through a check valve, the lower end of the alkali washing air inlet pipe extends below the liquid level of the alkali liquid neutralization tank, and the top inlet of the alkali liquid neutralization tank is connected to the bottom outlet of the alkali liquid preparation tank.

5. The PETG device tail gas treatment system according to claim 1, wherein: The bottom drain outlet of the tail gas scrubbing tower is connected to the inlet of the wastewater circulation pump, the outlet pipe of the wastewater circulation pump is connected to the hot side inlet of the scrubbing cooler, the hot side outlet of the scrubbing cooler is connected to the spray main pipe, and the spray main pipe is connected to the inlet of the spray device on each layer through the spray branch pipe, and the inlet of the spray device on the top layer is also connected to the clean water pipe.

6. The PETG device tail gas treatment system according to claim 5, wherein: Each spray branch pipe is also connected to the compressed air deblocking pipeline and the exhaust deblocking pipeline through a switching valve.

7. The PETG device tail gas treatment system according to claim 1, wherein: Each screen plate is provided with a plurality of diamond-shaped holes, and a diamond-shaped umbrella cap is provided above each diamond-shaped hole. The two corners of the bottom surface of each diamond-shaped umbrella cap are symmetrically connected with downwardly extending umbrella cap support feet, and the lower end of each umbrella cap support foot is bent outward to limit the maximum flying height of the diamond-shaped umbrella cap.

8. The PETG device tail gas treatment system according to claim 7, wherein: The area of ​​each diamond-shaped umbrella cap is larger than the diamond-shaped hole below, and the corners of each diamond-shaped hole are symmetrically provided with limiting protrusions that are higher than the plane of the screen plate.

9. The PETG device tail gas treatment system according to claim 7, wherein: The top surface of each diamond-shaped umbrella cap is in a cone shape with a high center and low surroundings.

10. The PETG device tail gas treatment system according to any one of claims 1 to 9, characterized in that: The diameter of the air outlet holes of each coil is 6-8mm.

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