CN213895682U

CN213895682U - Waste recycling's PET production system

Info

Publication number: CN213895682U
Application number: CN202023091070.2U
Authority: CN
Inventors: 朱昌全; 李立青
Original assignee: Oerlikon Barmag Huitong Yangzhou Engineering Co Ltd
Current assignee: Oerlikon Barmag Huitong Yangzhou Engineering Co Ltd
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2021-08-06
Anticipated expiration: 2030-12-21

Abstract

The utility model relates to a waste recovery PET production system, which comprises a slurry preparation tank, wherein a feed pipe of a PTA powder bin is connected with a powder inlet of the slurry preparation tank; the PET waste bin is connected with a waste inlet at the top of the slurry preparation tank through a waste feeding pipe; the top of the slurry preparation tank is also provided with a spraying column which extends vertically, the top of the spraying column is connected with a preparation tank exhaust pipe, an inner cavity of the spraying column is sequentially provided with an ethylene glycol and a catalyst spray head from top to bottom, the ethylene glycol feed pipe and the catalyst feed pipe are respectively provided with a control valve, and the opening degrees of the ethylene glycol flow control valve, the catalyst flow control valve and the waste material feeding valve are all controlled by the flow of the PTA feeding valve; the bottom export of thick liquids preparation jar links to each other with the entry of thick liquids conveying screw pump, and the export of thick liquids conveying screw pump links to each other with the feed inlet of esterifying a cauldron, and the bottom export of esterifying a cauldron links to each other with the feed inlet of esterifying two kettles. The system has short flow, less fixed investment, small occupied area and good stability.

Description

Waste recycling's PET production system

Technical Field

The utility model relates to a PET production system especially relates to a waste recycling's PET production system, belongs to polyester production technical field.

Background

Polyethylene terephthalate (PET) is a polyester series, and is prepared by exchanging dimethyl terephthalate with ethylene glycol or esterifying terephthalic acid (PTA) with Ethylene Glycol (EG) to synthesize dihydroxy ethyl terephthalate, and then performing polycondensation reaction. The bottle made of PET has the advantages of high strength, good transparency, no toxicity, permeation prevention, light weight, high production efficiency and the like, and is widely applied.

The PET production process always produces some wastes, and the existing PET waste recycling comprises three methods, namely a mechanical method, a homogenization method, a chemical alcoholysis method and the like. The mechanical method comprises the steps of extruding and melting PET solid waste materials by a screw extruder to obtain a PET melt, filtering, and then cutting into granules or spinning. The raw materials recovered by a mechanical method are large in storage occupied area, a certain gradient exists in the radial direction of the melt temperature in the melting and extruding processes of the screw extruder, the ring-knot phenomenon is easily caused by local high temperature, the content of impurities in the generated melt is high, and the material uniformity is poor and the quality is not stable enough. The mechanical recovery has extremely high requirement on the water content of the waste PET raw material, needs a separate drying system such as a rotary drum or a drying tower and the like, and has long drying time and high cost.

The homogenization method is that PET solid waste is firstly changed into PET melt through a screw extruder, the PET melt is sent to a homogenization kettle for further chemical reaction after primary filtration, the viscosity is adjusted and homogenized, the melt after reaction is conveyed through a gear pump, and is sent to be granulated or spun after being filtered again through a melt filter. In the homogenizing method recovery process, a small amount of impurities such as PVC and the like contained in the melt entering the homogenizing kettle can be pumped to a vacuum system and adhered to the inside of a vacuum pipeline, a condenser and the like, so that the vacuum system is polluted greatly; when reaching a certain degree, the vacuum capacity is reduced; the condenser, the filter and the like need to be cleaned regularly, the disassembly and the cleaning are frequent, and the labor intensity is high. The homogenization method also has extremely high requirements on the water content of the waste PET raw material, needs a separate drying system such as a rotary drum or a drying tower and the like, and has long drying time and high cost.

The conventional chemical alcoholysis method is that PET solid waste is subjected to chemical alcoholysis by using ethylene glycol to generate BHET (bis hydroxyethyl terephthalate) containing impurities, the BHET is subjected to processes of filtering, centrifuging, crystallizing and the like to form pure BHET, and the BHET is crushed and metered and then is added into a primary PET production device in a certain proportion. The conventional alcoholysis method has the disadvantages of complex process, more equipment, long flow, large fixed investment of production devices and high unit consumption and energy consumption of ethylene glycol and the like due to the fact that a monomer needs to be filtered, centrifuged and crystallized for many times.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome the problem that exists among the prior art, provide a waste recovery's PET production system, the flow is short, and the fixed investment is few, and area is little, and vacuum system's pollution is few, has improved the stability of production.

In order to solve the technical problem, the utility model discloses a waste recovery's PET production system, including thick liquids preparation jar and PTA feed bin, the bottom export of PTA feed bin is equipped with the PTA feed valve, the export of PTA feed valve passes through the PTA feed pipe with the powder entry at thick liquids preparation jar top links to each other; the PET waste bin is characterized by further comprising a PET waste bin, wherein a waste feeding valve is arranged at the bottom of the PET waste bin, and an outlet of the waste feeding valve is connected with a waste inlet at the top of the slurry preparation tank through a waste feeding pipe; the top of the slurry preparation tank is also provided with a spraying column extending vertically, the top of the spraying column is connected with a preparation tank exhaust pipe, an outlet of the preparation tank exhaust pipe is connected with an air inlet of a cyclone separator, a top exhaust port of the cyclone separator is connected with an induced draft fan, and a bottom outlet of the cyclone separator is connected with a powder inlet at the top of the slurry preparation tank through a separator return valve; the inner cavity of the spraying column is sequentially provided with an ethylene glycol spray head and a catalyst spray head from top to bottom, the ethylene glycol spray head is connected with an ethylene glycol feeding pipe, and the catalyst spray head is connected with the catalyst feeding pipe; the ethylene glycol feed pipe is provided with an ethylene glycol flow control valve, the catalyst feed pipe is provided with a catalyst flow control valve, and the opening degrees of the ethylene glycol flow control valve, the catalyst flow control valve and the waste material feeding valve are controlled by the flow of the PTA feeding valve; the bottom outlet of the slurry preparation tank is connected with the inlet of the slurry conveying screw pump, the outlet of the slurry conveying screw pump is connected with the feeding port of the first esterification kettle through a slurry output pipe, and the bottom outlet of the first esterification kettle is connected with the feeding port of the second esterification kettle.

As an improvement of the utility model, esterify one cauldron with esterify two top gas vents of cauldron all link to each other with the air inlet of esterification process tower, the bottom of esterification process tower is installed mellow wine liquid reflux pump, mellow wine liquid reflux pump's export through process tower back flow with esterify one cauldron and esterify two return ports at cauldron top and link to each other.

As a further improvement of the utility model, the top gas vent of the esterification process tower is connected with the tower top reflux tank through the tower top cooler, the liquid phase outlet of the tower top reflux tank is connected with the top reflux port of the esterification process tower.

As a further improvement of the utility model, the tank level gauge is installed to the bottom of thick liquids preparation jar, the flow of PTA feed valve is controlled by the thick liquids preparation jar liquid level that the tank level gauge surveyed of preparation.

As a further improvement of the utility model, the outlet of the slurry output pipe is connected with the backflow port of the slurry preparation tank through a slurry backflow pipe.

Compared with the prior art, the utility model discloses following beneficial effect has been obtained: 1. raw materials such as PET waste bottle piece fragments, bubble materials and the like with different shapes, sizes and the like are sliced in advance through a screw extruder and a die head, and dried to form PET waste regeneration slices or powder with relatively uniform shapes, so that the PET waste regeneration slices or powder are convenient to store and transport and stored in a PET waste bin, and the occupied area for storing the raw materials is reduced.

2. The low-temperature ethylene glycol enters the spraying column from the ethylene glycol feeding pipe and is sprayed downwards from the ethylene glycol spray head; the high-temperature catalyst enters the spraying column from the catalyst feeding pipe and is sprayed downwards from the catalyst spray head; because the temperature of the catalyst is high and the flow is small, and the temperature of the ethylene glycol is low and the flow is large, the catalyst spray head is closer to the slurry preparation tank, the ethylene glycol spray head is arranged above the catalyst spray head, and the ethylene glycol and the catalyst solution are mixed in the downward spraying process and then fall into the slurry preparation tank together; the PTA powder falls into the slurry preparation tank from a PTA powder bin and a PTA feeding pipe, and the PET waste is discharged from a PET waste bin and a waste feeding pipe and also falls into the slurry preparation tank according to a certain proportion; the evenly mixed slurry enters a slurry conveying screw pump from the bottom of a slurry preparation tank, and the slurry conveying screw pump conveys the prepared slurry into an esterification kettle through a slurry output pipe for esterification reaction.

3. The flow rates of the PET waste regeneration slices, the ethylene glycol and the catalyst are controlled by the flow rate of the PTA, so that the accurate molar ratio of the PET waste, the ethylene glycol, the catalyst and the PTA is kept, and the preparation quality of the slurry is higher.

4. Heating and alcoholysis are carried out on the waste PET particles by utilizing EG in the first esterification kettle to obtain regenerated BHET (BHET), namely dihydroxyethyl terephthalate), the regenerated BHET after alcoholysis and the original BHET are fully mixed in the first esterification kettle and then enter a subsequent second esterification kettle, and then enter a primary polymerization device, such as a pre-polycondensation kettle, a second polycondensation kettle, a final polymerization kettle and the like. The esterification kettle for producing the primary PET is utilized to complete the chemical reaction process of alcoholysis first and polycondensation second, and separate devices such as a homogenizing kettle, an alcoholysis kettle, a centrifugal machine, a crystallizer, ethylene glycol recovery and the like are not needed, so that the investment of fixed assets is greatly reduced, the process flow is shortened, and the quality of the regenerated PET is high.

5. The pollution of a vacuum system is less, and the production stability is improved; and a large amount of alcoholysis EG does not need to be added additionally, so that the consumption of EG is reduced.

6. Under the suction action of a draught fan, a micro-negative pressure state is kept in the slurry preparation tank, so that the blanking of PTA powder is facilitated, the powder is prevented from overflowing outwards due to positive pressure, tail gas upwards enters the spray column, floating PTA powder is sprayed through two stages of a catalyst spray head and an ethylene glycol spray head in the ascending process, most PTA powder is trapped and falls back to the slurry preparation tank, the dust content in the tail gas is reduced, a small amount of PTA powder enters the cyclone separator for separation, the PTA powder deposited at the bottom of the cyclone separator accumulates to a certain amount, a separator material return valve is opened, the PTA powder returns to the slurry preparation tank through a powder return pipe, and the PTA powder can be recycled completely, so that the loss of raw materials is reduced, the field operation environment is improved, and the environmental pollution is avoided.

7. The first esterification kettle and the second esterification kettle share one esterification process tower for rectification, trace EG and water vapor come out from the top of the tower and are cooled to become esterified water and liquid EG, one part of the esterified water and liquid EG flow back to the esterification process tower, and the other part of the esterified water and liquid EG flow over to a sewage treatment system. And the EG at the bottom of the esterification process tower flows back to the first esterification kettle or the second esterification kettle through an alcohol liquid reflux pump.

Drawings

The invention will be described in further detail with reference to the drawings and the detailed description, which are provided for reference and illustration purposes only and are not intended to limit the invention.

FIG. 1 is a flow chart of the PET production system for waste recycling according to the present invention.

In the figure: 1. a slurry preparation tank; 2. a slurry delivery screw pump; 3. a cyclone separator; 4. an induced draft fan; 5, a PTA powder bin; 6, PET waste bin; 7. esterification in a kettle; 8. esterification of the second kettle; 9. an esterification process column; 9a, a tower kettle ethylene glycol pump; 9b. overhead cooler; 9c, a tower top reflux tank; LT. make-up tank level gauge; F1. a glycol flow meter; F2. a catalyst flow meter; v1. a glycol flow control valve; v2. catalyst flow control valve; v3.pta feed valve; v4. waste feed valves; G1. a glycol feed pipe; G2. a catalyst feed pipe; g3.PTA feed pipe; G4. a powder material return pipe; G5. a slurry output pipe; G6. a waste feed pipe; G7. a slurry return pipe.

Detailed Description

As shown in fig. 1, the waste recycling PET production system of the present invention comprises a slurry preparation tank 1, a PTA powder bin 5 and a PET waste bin 6, wherein a PTA feeding valve V3 is disposed at the bottom outlet of the PTA powder bin 5, and the outlet of the PTA feeding valve V3 is connected to the powder inlet at the top of the slurry preparation tank 1 through a PTA feeding pipe G3; the bottom of the PET waste bin 6 is provided with a waste feeding valve V4, and the outlet of the waste feeding valve V4 is connected with a waste inlet at the top of the pulp preparation tank 1 through a waste feeding pipe G6; the top of the slurry preparation tank 1 is also provided with a spraying column extending vertically, the top of the spraying column is connected with a preparation tank exhaust pipe, the outlet of the preparation tank exhaust pipe is connected with the air inlet of the cyclone separator 3, the top exhaust port of the cyclone separator 3 is connected with the induced draft fan 4, and the bottom outlet of the cyclone separator 3 is connected with the powder inlet at the top of the slurry preparation tank 1 through the separator material return valve; the inner cavity of the spraying column is sequentially provided with a glycol spray head and a catalyst spray head from top to bottom, the glycol spray head is connected with a glycol feeding pipe G1, and the catalyst spray head is connected with a catalyst feeding pipe G2.

Under the suction action of the draught fan 4, the slurry preparation tank 1 is kept in a micro-negative pressure state, so that the blanking of PTA powder is facilitated, the phenomenon that powder overflows outwards due to positive pressure is avoided, tail gas upwards enters the spray column, floating PTA powder is sprayed by two stages of a catalyst spray head and an ethylene glycol spray head in the ascending process, most of PTA powder is collected and falls back into the slurry preparation tank 1, the dust content in the tail gas is reduced, a small amount of PTA powder enters the cyclone separator 3 for separation, the PTA powder deposited at the bottom of the cyclone separator 3 is accumulated to a certain amount, a separator return valve is opened, and the PTA powder returns into the slurry preparation tank 1 through a powder return pipe G4, so that the recovery of the raw material is completely achieved, the loss of the raw material is reduced, the field operation environment is improved, and the environmental pollution is avoided.

The bottom of the slurry preparation tank 1 is provided with a preparation tank liquid level meter LT, and the flow of the PTA feeding valve V3 is controlled by the slurry preparation tank liquid level measured by the preparation tank liquid level meter LT. The ethylene glycol feed pipe G1 is provided with an ethylene glycol flow meter F1 and an ethylene glycol flow control valve V1, and the catalyst feed pipe G2 is provided with a catalyst flow meter F2 and a catalyst flow control valve V2. The opening degrees of the ethylene glycol flow control valve V1, the catalyst flow control valve V2, and the waste feed valve V4 are all controlled by the flow rate of the PTA feed valve V3. The flow rates of the PET waste regeneration slices, the ethylene glycol and the catalyst are controlled by the flow rate of the PTA, so that the accurate molar ratio of the PET waste, the ethylene glycol, the catalyst and the PTA is kept, and the preparation quality of the slurry is higher.

The bottom export of thick liquids preparation jar 1 links to each other with the entry of thick liquids conveying screw pump 2, and the export of thick liquids conveying screw pump 2 passes through thick liquids output tube G5 and links to each other with the feed inlet of esterifying one cauldron 7, and the bottom export of esterifying one cauldron 7 links to each other with the feed inlet of esterifying two cauldron 8.

The top exhaust ports of the first esterification kettle 7 and the second esterification kettle 8 are connected with the air inlet of the esterification process tower 9, the bottom of the esterification process tower 9 is provided with an alcohol liquid reflux pump, and the outlet of the alcohol liquid reflux pump is connected with the reflux ports at the tops of the first esterification kettle 7 and the second esterification kettle 8 through a process tower reflux pipe.

The top exhaust port of the esterification process tower 9 is connected with the top reflux tank 9c through the top cooler 9b, and the liquid phase outlet of the top reflux tank 9c is connected with the top reflux port of the esterification process tower 9.

The outlet of the slurry outlet pipe G5 is also connected with the return port of the slurry preparation tank 1 through a slurry return pipe G7, so that the slurry outlet pipe G5 can keep a larger flow rate and prevent blockage.

The low-temperature glycol enters the spraying column from the glycol feed pipe G1 and is sprayed downwards from the glycol spray head; the high-temperature catalyst enters the spray column from the catalyst feed pipe G2 and is sprayed downwards from the catalyst spray head; because the temperature of the catalyst is high and the flow is small, and the temperature of the ethylene glycol is low and the flow is large, the catalyst spray head is closer to the slurry preparation tank 1, the ethylene glycol spray head is arranged above the catalyst spray head, and the ethylene glycol and the catalyst solution are mixed in the downward spraying process and then fall into the slurry preparation tank 1 together; PTA powder falls into the slurry preparation tank 1 from a PTA powder bin 5 and a PTA feed pipe G3, PET waste is discharged from a PET waste bin 6 and a waste feed pipe G6, and also falls into the slurry preparation tank 1 according to a certain proportion; the ethylene glycol and the catalyst which are uniformly distributed along the radius are mixed under the action of a stirrer of a preparation tank, the uniformly mixed slurry enters a slurry conveying screw pump 2 from the bottom of a slurry preparation tank 1, and the slurry conveying screw pump 2 conveys the prepared slurry into an esterification kettle for esterification reaction through a slurry output pipe G5.

The waste PET particles are heated and alcoholyzed by EG in the first esterification kettle 7 to form regenerated BHET (bis-hydroxyethyl terephthalate), and the regenerated BHET after alcoholysis and the primary BHET are fully mixed in the first esterification kettle 7 and then enter a subsequent second esterification kettle 8, and then continue to enter a primary polymerization device, such as a pre-polycondensation kettle, a second polycondensation kettle, a final polymerization kettle and the like. The esterification-kettle 7 for producing the primary PET is utilized to complete the chemical reaction process of alcoholysis and polycondensation, and separate devices such as a homogenizing kettle, an alcoholysis kettle, a centrifugal machine, a crystallizer, ethylene glycol recovery and the like are not needed, so that the investment of fixed assets is greatly reduced, the process flow is shortened, and the quality of the regenerated PET is high.

The first esterification kettle 7 and the second esterification kettle 8 share one esterification process tower 9 for rectification, trace EG and water vapor come out from the top of the tower and are cooled to become esterification water and liquid EG, one part of the esterification water and liquid EG flow back to the esterification process tower 9, and the other part of the esterification water and liquid EG flow back to a sewage treatment system. EG at the bottom of the esterification process tower 9 reflows to the first esterification kettle 7 or the second esterification kettle 8 through a tower kettle ethylene glycol pump 9a.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention. In addition to the above embodiments, the present invention can also have other embodiments, for example, the terephthalic acid supply can be isophthalic acid and adipic acid supply, the ethylene glycol supply pipe can be propylene glycol and butanediol supply pipes, and the waste slice supply pipe can be waste materials such as slices, powder, sheets and blocks. All the technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope claimed by the present invention. The undescribed technical features of the present invention can be realized by or using the prior art, and are not described herein again.

Claims

1. A waste recovery PET production system comprises a slurry preparation tank and a PTA powder bin, wherein a PTA feeding valve is arranged at an outlet at the bottom of the PTA powder bin, and an outlet of the PTA feeding valve is connected with a powder inlet at the top of the slurry preparation tank through a PTA feeding pipe; the method is characterized in that: the PET waste bin is characterized by further comprising a PET waste bin, wherein a waste feeding valve is arranged at the bottom of the PET waste bin, and an outlet of the waste feeding valve is connected with a waste inlet at the top of the slurry preparation tank through a waste feeding pipe; the top of the slurry preparation tank is also provided with a spraying column extending vertically, the top of the spraying column is connected with a preparation tank exhaust pipe, an outlet of the preparation tank exhaust pipe is connected with an air inlet of a cyclone separator, a top exhaust port of the cyclone separator is connected with an induced draft fan, and a bottom outlet of the cyclone separator is connected with a powder inlet at the top of the slurry preparation tank through a separator return valve; the inner cavity of the spraying column is sequentially provided with an ethylene glycol spray head and a catalyst spray head from top to bottom, the ethylene glycol spray head is connected with an ethylene glycol feeding pipe, and the catalyst spray head is connected with the catalyst feeding pipe; the ethylene glycol feed pipe is provided with an ethylene glycol flow control valve, the catalyst feed pipe is provided with a catalyst flow control valve, and the opening degrees of the ethylene glycol flow control valve, the catalyst flow control valve and the waste material feeding valve are controlled by the flow of the PTA feeding valve; the bottom outlet of the slurry preparation tank is connected with the inlet of the slurry conveying screw pump, the outlet of the slurry conveying screw pump is connected with the feeding port of the first esterification kettle through a slurry output pipe, and the bottom outlet of the first esterification kettle is connected with the feeding port of the second esterification kettle.

2. The scrap recycling PET production system according to claim 1, characterized in that: the top exhaust ports of the first esterification kettle and the second esterification kettle are connected with an air inlet of an esterification process tower, an alcohol liquid reflux pump is installed at the bottom of the esterification process tower, and an outlet of the alcohol liquid reflux pump is connected with reflux ports at the tops of the first esterification kettle and the second esterification kettle through a process tower reflux pipe.

3. The scrap recycling PET production system according to claim 2, characterized in that: and a top exhaust port of the esterification process tower is connected with a tower top reflux tank through a tower top cooler, and a liquid phase outlet of the tower top reflux tank is connected with a top reflux port of the esterification process tower.

4. The scrap recycling PET production system according to claim 1, characterized in that: and a preparation tank liquid level meter is installed at the bottom of the slurry preparation tank, and the flow of the PTA feeding valve is controlled by the slurry preparation tank liquid level measured by the preparation tank liquid level meter.

5. The scrap recycling PET production system according to any one of claims 1 to 4, characterized in that: the outlet of the slurry output pipe is also connected with the reflux port of the slurry preparation tank through a slurry reflux pipe.