CN212560068U - Production system of biodegradable polyester - Google Patents

Production system of biodegradable polyester Download PDF

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CN212560068U
CN212560068U CN202020717946.0U CN202020717946U CN212560068U CN 212560068 U CN212560068 U CN 212560068U CN 202020717946 U CN202020717946 U CN 202020717946U CN 212560068 U CN212560068 U CN 212560068U
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esterification
outlet
kettle
tank
port
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曾庆
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Yangzhou Huitong Technology Co ltd
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Yangzhou Huitong Technology Co ltd
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Abstract

The utility model relates to a production system of biodegradable polyester, the esterification reaction kettle comprises an A esterification kettle, a T esterification kettle and an esterification two reaction kettle, a slurry inlet at the top of the A esterification kettle is connected with an outlet of a slurry finished product tank I, a top inlet of the slurry finished product tank I is connected with an outlet of a slurry mixing tank I, and the top of the slurry mixing tank I is connected with a BDO feed pipe and is provided with a PTA feed port; a slurry inlet at the top of the T esterification kettle is connected with an outlet of a slurry finished product tank II, a top inlet of the slurry finished product tank II is connected with an outlet of a slurry mixing tank II, and the top of the slurry mixing tank II is connected with a BDO feeding pipe and is provided with an AA feeding port; the outlets of the esterification kettle A and the esterification kettle T are respectively connected with the inlet of the esterification secondary reaction kettle, the outlet of the esterification secondary reaction kettle is connected with the inlet of the pre-polycondensation reaction kettle, the pre-polycondensation outlet is connected with the inlet of the final polycondensation reaction kettle, and the final polycondensation outlet is connected with the tackifying reaction kettle. The system can reduce BDO consumption, THF generation and manufacturing cost.

Description

Production system of biodegradable polyester
Technical Field
The utility model relates to a polyester production system especially relates to a biodegradable polyester's production system, belongs to polyester production facility technical field.
Background
Polybutylene terephthalate adipate (PBAT) is a biodegradable material, the product waste of which can be quickly degraded in soil or water, and the degradation product of which is non-toxic. PBAT is aliphatic polyester obtained by esterification polymerization of terephthalic acid, adipic acid and 1, 4-butanediol, has wide application, and can be prepared into disposable shopping bags, agricultural films, biomedical polymer materials, packaging bottles and the like. With the white pollution problem and the increasing non-renewable energy crisis, PBAT is used more and more widely.
PBAT is a linear polymer material and is easy to degrade when heated. PBAT is expensive, starch and polylactic acid are usually blended to obtain a low-price degradable plastic product, and the application range of PBAT is widened. At present, the global demand of PBAT is mainly concentrated in Europe and America, the total demand is less, and the market is limited.
In the prior art, terephthalic acid, adipic acid and 1, 4-butanediol are pulped according to a certain proportion, then sent to an esterification first reaction kettle for reaction, sent to an esterification second reaction kettle for further reaction after the reaction, and then subjected to polycondensation I, polycondensation II, final polycondensation, tackifying and granulating (or granulating, chain extending, tackifying and granulating again), and selling downstream customers.
The existing PBAT production systems have the following problems: 1. terephthalic Acid (PTA), Adipic Acid (AA) and 1,4 Butanediol (BDO) are subjected to esterification reaction together, in order to ensure the reaction of terephthalic acid and 1,4 butanediol, the esterification temperature is up to 230-250 ℃, the 1,4 butanediol has serious side reaction and large consumption, the generation amount of Tetrahydrofuran (THF) is large, and the pressure of a tetrahydrofuran treatment device is increased.
2. The esterification reaction kettle has large volume, strong corrosivity of adipic acid in a high-temperature environment with water, high investment cost of the device and poor market competitiveness, and the material requirement of the esterification reaction kettle is over 316L.
3. The esterification catalyst is a titanium catalyst, and is easily hydrolyzed to form a titanium compound when meeting water, so that a pipeline is blocked, and the production stability is influenced.
4. The esterification reaction is provided with an independent liquid ring pump group, so that the water consumption is large, the wastewater quantity is large, the pressure of a tetrahydrofuran recovery system is increased, and the method is not friendly to water resource environment.
5. The pre-polycondensation is divided into a polycondensation system I and a polycondensation system II, so that a plurality of devices and systems are provided, and the equipment investment cost is high.
6. The polycondensation and tackifying vacuum systems are divided into two sets, the BDO evaporators, the BDO jet pumps and the mechanical vacuum pumps are all provided with two sets, and the equipment investment cost is high; the required layout area is also large, and the civil engineering cost is high.
7. The esterification polycondensation vacuum is mutually independent, a plurality of sets of vacuum equipment are needed, and the equipment investment cost is high; the required layout area is also large, and the civil engineering cost is high.
8. The two-step modification increases the intermediate process, thereby not only increasing the possibility of melt degradation, but also increasing the equipment investment.
9. The vacuum spraying system is easy to block, cannot be cleaned on line, and has overhigh cleaning cost and poor system stability.
10. Only PBAT can be produced, the product is single, and the market competitiveness is poor.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome the problem that exists among the prior art, provide a production system of biodegradable polyester, can reduce BDO's consumption by a wide margin, reduce tetrahydrofuran's production, and reduce manufacturing cost.
In order to solve the technical problem, the utility model discloses a production system of biodegradable polyester, including esterification reaction cauldron, pre-polycondensation reaction cauldron and final polycondensation reaction cauldron, esterification reaction cauldron includes A esterification reaction cauldron, T esterification reaction cauldron and two reaction kettles of esterifying, and the thick liquids entry at A esterification reaction cauldron top links to each other with the discharge gate of thick liquids finished product jar one, and the top entry of thick liquids finished product jar one links to each other with the discharge gate of thick liquids blending jar one, and the top of thick liquids blending jar one links to each other with BDO feed pipe and is equipped with the PTA dog-house; a slurry inlet at the top of the T esterification kettle is connected with a discharge hole of a slurry finished product tank II, a top inlet of the slurry finished product tank II is connected with a discharge hole of a slurry mixing tank II, and the top of the slurry mixing tank II is connected with a BDO feed pipe and is provided with an AA feed port; the discharge ports of the esterification kettle A and the esterification kettle T are respectively connected with the feed port of the esterification reaction kettle, the discharge port of the esterification reaction kettle is connected with the feed port of the pre-polycondensation reaction kettle, the discharge port of the pre-polycondensation reaction kettle is connected with the feed port of the final polycondensation reaction kettle, and the discharge port of the final polycondensation reaction kettle is connected with the feed port of the tackifying reaction kettle.
Compared with the prior art, the utility model discloses following beneficial effect has been obtained: 1,4 Butanediol (BDO) and terephthalic acid (PTA) are prepared in a slurry preparation tank I in batches according to a certain molar ratio, are fully and uniformly stirred and then are sent into a slurry finished product tank I by virtue of a liquid level difference, and then enter an esterification kettle A from the slurry finished product tank I to carry out esterification reaction; and the BDO and the adipic acid AA are prepared in a slurry preparation tank II in batches according to a certain molar ratio, are fully and uniformly stirred and then are sent into a slurry finished product tank II by virtue of a liquid level difference, and then enter a T esterification kettle from the slurry finished product tank II to carry out esterification reaction. Because the reaction temperature of adipic acid and 1,4 butanediol is low and the reaction temperature of terephthalic acid and 1,4 butanediol is high, the esterification reaction is separately carried out according to the difference of the temperature and the pressure required by the reaction, thereby greatly reducing the consumption of BDO and reducing the generation of tetrahydrofuran. And respectively feeding the esterified ester T and the esterified ester A into an esterification secondary reaction kettle for mixed esterification, feeding the mixed esterified material into a pre-polycondensation reaction kettle for pre-polycondensation, feeding the pre-polycondensation material into a final polycondensation reaction kettle for final polycondensation, and feeding the final polycondensation material into a tackifying reaction kettle for tackifying. 316L stainless steel is used as the material of the A esterification kettle for the reaction of adipic acid and 1,4 butanediol, 304 stainless steel is used as the material of the T esterification kettle for the reaction of terephthalic acid and 1,4 butanediol, and the manufacturing cost can be reduced.
As the improvement of the utility model, the discharge gate of tackification reation kettle passes through the measuring pump and links to each other with screw extruder, and screw extruder's entry end still is equipped with the modified material input port, and screw extruder's discharge gate links to each other with cutting the grain system. Other modified materials can be directly added into the melt according to a certain proportion through the modified material input port, and the modified materials are melted, mixed, plasticized and extruded in the screw extruder and enter the granulating system for granulating. The system adopts online mixing modification, directly saves a modification production line, and greatly reduces the cost; the market competitiveness is strong; meanwhile, the online modification has short melt line, short residence time, difficult thermal decomposition and good product quality; meanwhile, the system has good compatibility, can produce products with different characteristics, and meets different downstream customers.
As a further improvement of the utility model, the tops of the esterification kettle A, the esterification kettle T and the esterification reaction kettle II are respectively provided with a pressure transmitter, the gas phase ports at the tops of the esterification kettle A, the esterification kettle T and the esterification reaction kettle II are respectively connected with the gas inlet of the process tower through respective vacuum regulating valves, and the opening degree of each vacuum regulating valve is respectively controlled by the pressure in the kettle measured by the corresponding pressure transmitter; the gas phase outlet of the tower top condenser is connected with the gas phase outlet of the tower top condenser, the bottom outlet of the tower top receiving tank is connected with the reflux port at the upper part of the process tower, the overflow port of the tower top receiving tank is connected with the tetrahydrofuran recovery device, the gas phase outlet of the tower top condenser is connected with the extraction port of the mechanical vacuum pump through a vacuum regulating valve IV, the opening degree of the vacuum regulating valve IV is controlled by the pressure measured by a pressure transmitter IV, and the pressure transmitter IV is arranged at the gas phase outlet of the tower top condenser. The esterification kettle A, the esterification kettle T and the esterification reaction kettle II share one process tower, a first pressure transmitter is installed at the top of the esterification kettle A, a gas phase port of the esterification kettle A is connected with a gas inlet of the process tower through a first vacuum regulating valve, and the opening degree of the first vacuum regulating valve is controlled by the pressure in the esterification kettle A measured by the first pressure transmitter; the top of the T esterification kettle is provided with a second pressure transmitter, a gas phase port of the T esterification kettle is connected with a gas inlet of the process tower through a second vacuum regulating valve JV2, and the opening degree of the second vacuum regulating valve JV2 is controlled by the pressure in the T esterification kettle measured by the second pressure transmitter; the top of the esterification secondary reaction kettle is provided with a third pressure transmitter, a gas phase port of the esterification secondary reaction kettle is connected with a gas inlet of the process tower through a third vacuum regulating valve, and the opening degree of the third vacuum regulating valve is controlled by the pressure in the esterification secondary reaction kettle measured by the third pressure transmitter. The esterification reaction generates ester, higher molecular oligomer, water and BDO to generate tetrahydrofuran by cyclization at high temperature. The water and Tetrahydrofuran (THF) generated in the esterification process enter a process tower for rectification, liquid heating medium is adopted at the bottom of the process tower for heating, the recovered BDO discharged at the bottom of the tower is returned to a reflux port of an esterification kettle, water and THF evaporated at the top of the tower are condensed by a condenser at the top of the tower and then enter a receiving tank at the top of the tower, one part of the water and the THF are used as reflux of the process tower, and the rest part of the water and the THF enter a tetrahydrofuran recovery device. Because the tail gas quantity of the tower top condenser is small, the vacuum degree requirement can be met by utilizing a mechanical vacuum pump for subsequent polycondensation, and the system cancels an independent liquid ring pump set, thereby not only saving the investment, but also reducing the consumption of water resources and the treatment and discharge of pollutants.
As a further improvement of the utility model, the centers of the bottoms of the esterification kettles A and the esterification kettles T are respectively connected with a catalyst feed pipe, the inner cavities of the two esterification reaction kettles are divided into an outer esterification kettle chamber and an inner esterification kettle chamber by an annular esterification kettle baffle plate, a discharge port of the esterification kettle is positioned at the bottom of the outer esterification kettle chamber, an inner esterification kettle cylinder is arranged at the center of the lower part of the inner esterification kettle chamber, and esterification kettle heating tubes are distributed in the annular space at the periphery of the inner esterification kettle cylinder; and a nitrogen ring blowing pipe is arranged below the inner cylinder of the esterification kettle, the radius of the nitrogen ring blowing pipe is smaller than that of the inner cylinder of the esterification kettle, the nitrogen ring blowing pipe and the inner cylinder of the esterification kettle share the same axis, spray holes blowing to the bottom of the kettle are uniformly distributed along the circumference of the lower part of the nitrogen ring blowing pipe, and an air source pipeline of the nitrogen ring blowing pipe penetrates through the heating tube array of the esterification kettle and upwards extends out of the top of the esterification reaction kettle. The catalyst tetrabutyl titanate is easy to hydrolyze when meeting water, so the catalyst inlet is arranged at the bottom of the kettle, and the contact of the catalyst and the water is avoided as much as possible; because the esterification reaction can generate a large amount of water in the esterification reaction kettle, the density of the water is low; set up round nitrogen ring blowpipe in the top of catalyst entry, utilize nitrogen partial pressure, in time the desorption moisture plays the bubbling stirring effect simultaneously, makes the catalyst that gets into in the cauldron mix with the ester fast for the dissolving rate of catalyst in the ester avoids contacting with water, reduces the use amount of catalyst.
As the utility model discloses a further improvement, the polycondensation reation kettle in advance includes by the median septum divided last preshrinking the room and preshrinking the room down, two reation kettle's of esterifying discharge gate and last preshrinking the feed inlet of gathering the room and link to each other, go up the discharge gate of preshrinking the room and link to each other through intercommunication return bend and the feed inlet of preshrinking the room down, preshrinking down the discharge gate of gathering the room with the feed inlet of final polycondensation reation kettle links to each other. The pre-polycondensation reaction kettle adopts an upper chamber and a lower chamber, materials in the upper chamber react to a certain degree of polymerization, and enter the lower chamber through a potential difference to perform further polycondensation reaction. The combination of two reaction forms of plug flow and full mixing is realized, the one-time investment cost is saved, and the efficiency of the reactor is improved.
As a further improvement of the utility model, the gas phase port of the pre-polycondensation reaction kettle is connected with the gas inlet of the first scraper condenser, the gas phase port of the final polycondensation reaction kettle is connected with the gas inlet of the second scraper condenser, the gas phase port of the tackifying reaction kettle is connected with the gas inlet of the third scraper condenser, the bottom liquid outlet of each scraper condenser is respectively connected with the corresponding hot well through the atmospheric leg, the first outlet of each hot well is connected with the inlet of the first filter through the first hot well outlet valve, the outlet of the first filter is connected with the inlet of the first circulating pump, the outlet of the first circulating pump is connected with the inlet of the first cooler, the outlet of the first cooler is connected with the first circulating pipe, the outlet of the first circulating pipe is respectively connected with the first spray valve and the first reflux valve, the outlet of the first spray valve is connected with the first spray port on the upper part of the first scraper condenser, the outlet of the first reflux valve is connected with the top reflux, the bottom of the lye tank is connected with a lye tank outlet pipe, and the lye tank outlet pipe is connected with an inlet of the first filter through a first cleaning valve; the second outlet of the hot well is connected with the inlet of the second filter through a second hot well outlet valve, the outlet of the second filter is connected with the inlet of a second circulating pump, the outlet of the second circulating pump is connected with the inlet of a second cooler, the outlet of the second cooler is connected with a second circulating pipe, the outlet of the second circulating pipe is respectively connected with a second spray valve and a second return valve, the outlet of the second spray valve is connected with a second spray port on the upper part of the scraper condenser, the outlet of the second return valve is connected with the BDR return pipe, and the outlet pipe of the alkaline solution tank is connected with the inlet of the second filter through a second cleaning valve. Each scraper condenser is provided with two circulating spraying lines, one is used for standby, a first hot well outlet valve and a first spraying valve are opened, a second hot well outlet valve and a first backflow valve are closed, the discharged liquid of each scraper condenser enters an inner chamber of a hot well through an atmosphere leg, enters an outer chamber of the hot well after being filtered, is pumped out by a first circulating pump, is filtered by a first filter, is cooled by a first cooler and then enters the upper part of the scraper condenser through a first circulating pipe and the first spraying valve for spraying; after the process steam generated by the polycondensation reaction enters the scraper condenser from the polycondensation gas phase pipe, most BDO and entrained oligomer micromolecules are condensed by liquid phase spraying, and the uncaptured process gas is discharged from the top of the scraper condenser and is pumped out. Due to the side reactions of the PBAT polycondensation reaction and the formation of a lot of oligomers, the first circulation spray line will clog up after a period of operation. And at the moment, the first hot well outlet valve and the first spray valve are closed, the second hot well outlet valve and the second spray valve are opened, and the second circulating spray line is directly switched on without stopping, so that the vacuum degree of the PBAT production line is maintained to be not fluctuated, and continuous and stable production is ensured. The first cleaning valve and the first return valve are opened simultaneously, alkali liquor in the alkali liquor tank enters the first circulating pump through the first alkali liquor tank outlet pipe and the first filter, the first circulating pump sends the alkali liquor into the first cooler and the first circulating pipe, the first return valve and the BDR return pipe return to the alkali liquor tank, the alkali liquor tank can supplement the alkali liquor through the alkali liquor supply pipe, the oligomer is effectively dissolved by the alkali liquor, the pipeline is blocked by online cleaning, the cleaning process is pollution-free, the production process is not stopped, the system stability is good, and continuous production is guaranteed.
As a further improvement of the utility model, the top exhaust port of the third scraper condenser is connected with the suction port of the first-level steam jet pump, the top exhaust port of the second scraper condenser is connected with the suction port of the second-level steam jet pump, the top exhaust port of the first scraper condenser is connected with the suction port of the fourth-level steam jet pump, the outlets of the first-level steam jet pump and the second-level steam jet pump are both connected with the air inlet of the first condensing tank, the exhaust port of the first condensing tank is connected with the suction port of the third-level steam jet pump, the outlets of the third-level steam jet pump and the fourth-level steam jet pump are both connected with the air inlet of the second condensing tank, the exhaust port of the second condensing tank is connected with the suction port of the fifth-level steam jet pump, the outlet of the third condensing tank is connected with the suction port of the sixth-level steam jet pump, the exhaust port of the sixth-level steam jet pump is connected with, an exhaust port at the lower part of the vacuum condenser is connected with an inlet of the mechanical vacuum pump through a vacuum-pumping pipe, and an outlet of the mechanical vacuum pump is connected with a middle inlet of the gas-liquid separation tank; the top outlet of the gas-liquid separation tank is connected with the heating medium furnace; and the bottom outlet of the gas-liquid separation tank is connected with the tetrahydrofuran recovery device. The esterification, polycondensation and tackifying share one set of vacuum system, so that a large amount of accessory equipment is reduced, equipment investment and civil engineering investment cost are reduced, the consumption of land resources is reduced, and the efficiency of the vacuum system is improved; the suction force required by the gas phase port of the tackifying reaction kettle is greater than that of the gas phase port of the final polycondensation reaction kettle, and the suction force required by the gas phase port of the final polycondensation reaction kettle is greater than that of the gas phase port of the pre-polycondensation reaction kettle, so that the gas phase port of the tackifying reaction kettle is connected with a first-stage steam jet pump, and the gas phase port of the pre-polycondensation reaction kettle is connected with a fourth-stage steam jet pump; exhaust gas of a third scraper condenser of a tackifying section is pumped out by a first-stage steam jet pump, exhaust gas of a second scraper condenser of a final condensation section is pumped out by a second-stage steam jet pump, the first stage and the second stage jointly enter a first condensation tank for condensation, exhaust gas of the first condensation tank is pumped out by a third-stage steam jet pump, exhaust gas of the first scraper condenser of a pre-condensation section is pumped out by a fourth-stage steam jet pump, the third stage and the fourth stage jointly enter a second condensation tank for condensation, exhaust gas of the second condensation tank is pumped out by a fifth-stage steam jet pump and then enters a third condensation tank for condensation, exhaust gas of the third condensation tank is pumped out by a sixth-stage steam jet pump and enters a tube pass of a vacuum condenser for condensation, and BDO and oligomers in process steam generated by polycondensation reaction are captured by adopting a circulating spraying mode, so that the load of a vacuum system is reduced, full recycling of BD. The shell pass of the vacuum condenser uses chilled water to carry out indirect condensation, can effectively condense water generated by BDO cyclization, reduces the subsequent vacuum pressure, can select a smaller mechanical vacuum pump, and reduces the investment. BDO is easy to generate cyclization reaction to generate tetrahydrofuran which is a low-boiling-point substance and is difficult to capture, and the tetrahydrofuran is easy to accumulate in a liquid ring vacuum pump set to cause the reduction of the vacuum degree of the system. A gas-liquid separator is added at the rear end of the mechanical vacuum pump, condensate enters a tetrahydrofuran recovery device for recycling, and non-condensable gas enters a heating medium furnace for use as fuel, so that the environment is protected, and the energy consumption is reduced.
As a further improvement of the utility model, the power ports of all stages of steam jet pumps are connected with a BDO steam pipe, the pipe pass inlet of the vacuum condenser and the top spray ports of all stages of condensing tanks are connected with a cold BDO pipe, the bottom liquid discharge port of each stage of condensing tank is connected with a condensing tank liquid discharge pipe, the lower end of each condensing tank liquid discharge pipe is inserted into a vacuum liquid seal tank, the bottom liquid discharge port of the vacuum liquid seal tank is connected with the inlet of a circulating pump of the vacuum liquid seal tank, the outlet of the circulating pump of the vacuum liquid seal tank is connected with the inlet of a cooler of a vacuum system, and the outlet of the cooler of the vacuum system is connected with the cold BDO pipe; the tube pass outlet of the vacuum condenser is connected with a condenser discharge pipe, overflow pipes of the condenser discharge pipe, the vacuum liquid seal tank and overflow pipes of the thermal wells are respectively connected with the BDR low-level tank, a liquid discharge port at the bottom of the BDR low-level tank is connected with an inlet of the BDR delivery pump, and an outlet of the BDR delivery pump is connected with a return port in the middle of the process tower and the BDO feeding pipe through a BDR return pipe. The BDO steam pipe provides power for each steam jet pump, cold BDO is sprayed in each stage of condensing tank to capture BDO and low polymers in process steam generated by polycondensation, spray liquid enters a vacuum liquid seal tank through each condensing tank liquid discharge pipe to be collected, BDO on the right side in the vacuum liquid seal tank is pumped out by a vacuum liquid seal tank circulating pump, is cooled by a vacuum system cooler and is sent into the cold BDO pipe to be sprayed circularly. The vacuum liquid seal tank and BDO overflowing from each hot well all enter the BDR low-level tank to be collected, the BDR delivery pump sends the recovered 1, 4-butanediol back to the slurry mixing tank I, the slurry mixing tank II and the process tower through the BDR delivery pipe for recycling, and the complete recycling of the BDR materials is realized.
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 a system for producing biodegradable polyester according to the present invention.
FIG. 2 is a detailed view of the connection between the esterification kettle A and the process tower.
FIG. 3 is a schematic diagram of the structure of the esterification tank A or the esterification tank T in FIG. 1.
FIG. 4 is a cross-sectional view of the portion of the esterification tank ring baffle of FIG. 3.
FIG. 5 is a cross-sectional view of the heated tube array portion of the esterification kettle of FIG. 3.
Fig. 6 is a bottom view of the nitrogen ring torch of fig. 3.
FIG. 7 is a flow diagram of another embodiment of a blade condensation system.
In the figure: 1a, a first slurry mixing tank; 1b, a second slurry mixing tank; 2a, a first slurry finished product tank; 2b, a slurry finished product tank II; 3-1.A esterification kettle; 3-2.T esterification kettle; 3a, an esterification kettle slurry inlet; 3b, a gas phase port of the esterification kettle; 3c, an esterification kettle stirring port; 3d, discharging a material outlet of the esterification kettle; 3e, a catalyst inlet; 3f, an esterification kettle annular baffle; 3f1. discharging the material slot; 3g, a discharging partition plate of the esterification kettle; heating the tube array of the esterification kettle for 3 hours; 3h1. esterification kettle tubular heat medium inlet; 3h2. esterification kettle tubular heat medium outlet; 3j, an inner cylinder of the esterification kettle; 3k, a reflux opening of the esterification kettle; 3m. an esterification kettle jacket; 3m1. esterification kettle jacket heating medium inlet; 3m2. an esterification kettle jacket heat medium outlet; 3n, performing annular blowing on nitrogen; 4. esterification reaction kettle II; 5. a process tower; 5a, a tower top condenser; 5b, a tower top receiving tank; 6. a pre-polycondensation reaction kettle; 7. a final polycondensation reaction kettle; 8. a tackifying reaction kettle; 9. a screw extruder; 9a, a modified material input port; 10. a pelletizing system; 11-1, a first scraper condenser; 11-2, a second scraper condenser; 11-3, a third scraper condenser; atmospheric leg 11 a; 12. a hot well; 13. cleaning the box; 14. an alkali liquor tank; 15. a vacuum condenser; 16. a mechanical vacuum pump; 17. a gas-liquid separation tank; 18. a heat medium furnace; 19. tetrahydrofuran recovery unit.
V1a. a hot well outlet valve i; v1b. hot well outlet valve II; v2a, a first spray valve; v2b. a second spray valve; v3a. a first reflux valve; v3b. a second return valve; v4a. a first purge valve; v4b. a second purge valve; v5a. a first drain valve; v5b. discharge valve II; v6. nitrogen gas valve; v7. refrigerant water regulating valve; v8. high temperature heating medium feed regulating valve; v9. high temperature heating medium return valve; l1, a first filter; l2, a second filter; B1. a first circulating pump; B2. a second circulating pump; B3. a vacuum liquid-sealed tank circulating pump; B4. a heating medium pump of the esterification kettle; C1. a first cooler; C2. a second cooler; C3. a vacuum system cooler; p1, a primary steam jet pump; p2, a secondary steam jet pump; p3, a three-stage steam jet pump; p4. a four-stage steam jet pump; p5. five-stage steam jet pump; p6, a six-stage steam jet pump; J1. a first condensation tank; J2. a second condensation tank; J3. a third condensation tank; J4. vacuum liquid sealing the tank; j5.bdr low-level tank; g1.BDO feed pipe; G2. a catalyst feed pipe; g3a, a first circulating pipe; g3b, circulating pipe II; g4.BDR reflux pipe; G5. an outlet pipe of the lye tank; g6.BDO steam pipe; G7. a cold BDO tube; G8. a liquid discharge pipe of the condensation tank; G9. a condenser discharge pipe; G10. vacuumizing a tube; G11. an alkali liquor supply pipe; G12. a nitrogen gas pipe; g13.BDR delivery pipe; s1, a high-temperature heat medium supply pipe; s2, a high-temperature heat medium return pipe; s3, a refrigerant water supply pipe; s4, a refrigerant return pipe; E1. a first pressure transmitter; E2. a second pressure transmitter; E3. a third pressure transmitter; E4. a pressure transmitter IV; E5. a fifth pressure transmitter; E6. a pressure transmitter six; E7. a seventh pressure transmitter; E8. eighthly, a pressure transmitter; JV1, a first vacuum regulating valve; JV2, a vacuum regulating valve II; JV3, a vacuum regulating valve III; JV4. vacuum regulating valve IV; JV5, a vacuum adjusting valve V; JV6. a vacuum adjusting valve VI; JV7. vacuum regulating valve seventh; t1, an esterification material temperature transmitter; t2, an esterification heat medium temperature transmitter; and T3, a vacuum tube temperature transmitter.
Detailed Description
As shown in fig. 1, the production system of biodegradable polyester of the present invention comprises an esterification reaction kettle, a pre-polycondensation reaction kettle 6 and a final polycondensation reaction kettle 7, wherein the esterification reaction kettle comprises an esterification kettle 3-1, an esterification kettle 3-2 and an esterification secondary reaction kettle 4, the slurry inlet at the top of the esterification kettle 3-1 is connected with the discharge port of a slurry finished product tank I2 a, the top inlet of the slurry finished product tank I2 a is connected with the discharge port of a slurry blending tank I1 a, and the top of the slurry blending tank I1 a is connected with a BDO feed pipe G1 and is provided with a PTA feed port; a slurry inlet at the top of the T esterification kettle 3-2 is connected with a discharge hole of a slurry finished product tank II 2b, a top inlet of the slurry finished product tank II 2b is connected with a discharge hole of a slurry mixing tank II 1b, and the top of the slurry mixing tank II 1b is connected with a BDO feed pipe G1 and is provided with an AA feed port; the discharge ports of the esterification reactor A3-1 and the esterification reactor T3-2 are respectively connected with the feed port of the esterification secondary reaction kettle 4, the discharge port of the esterification secondary reaction kettle 4 is connected with the feed port of the pre-polycondensation reaction kettle 6, the discharge port of the pre-polycondensation reaction kettle 6 is connected with the feed port of the final polycondensation reaction kettle 7, and the discharge port of the final polycondensation reaction kettle 7 is connected with the feed port of the tackifying reaction kettle 8.
1,4 Butanediol (BDO) and terephthalic acid (PTA) are prepared in a slurry preparation tank I1 a in batches according to a certain molar ratio, are conveyed into a slurry finished product tank I2 a by virtue of liquid level difference after being fully and uniformly stirred, and then enter an esterification kettle A3-1 from the slurry finished product tank I2 a to carry out esterification reaction; and the BDO and the adipic acid AA are prepared in the slurry preparation tank II 1b in batches according to a certain molar ratio, are fully and uniformly stirred and then are sent into the slurry finished product tank II 2b by means of liquid level difference, and then enter the T esterification kettle 3-2 from the slurry finished product tank II 2b to carry out esterification reaction. Because the reaction temperature of adipic acid and 1,4 butanediol is low and the reaction temperature of terephthalic acid and 1,4 butanediol is high, the esterification reaction is separately carried out according to the difference of the temperature and the pressure required by the reaction, thereby greatly reducing the consumption of BDO and reducing the generation of tetrahydrofuran. The esterified ester of T and esterified ester of A are sent into esterification two reaction vessel 4 separately and mixed and esterified, the mixed esterified material enters pre-polycondensation reaction vessel 6 to carry on the pre-polycondensation, the pre-polycondensation polymer material enters final polycondensation reaction vessel 7 to carry on the final polycondensation, the final polycondensation polymer material enters tackifying reaction vessel 8 to tackify. 316L stainless steel is used as the material of the A esterification kettle 3-1 for the reaction of adipic acid and 1,4 butanediol, 304 stainless steel is used as the material of the T esterification kettle 3-2 for the reaction of terephthalic acid and 1,4 butanediol, and the manufacturing cost can be reduced.
The discharge port of the tackifying reaction kettle 8 is connected with the screw extruder 9 through a metering pump, the inlet end of the screw extruder 9 is also provided with a modified material inlet 9a, and the discharge port of the screw extruder 9 is connected with a pelletizing system 10. Other modified materials can be directly added into the melt according to a certain proportion through the modified material input port 9a, and the modified materials are melted, mixed, plasticized and extruded in the screw extruder 9 and enter the granulating system 10 for granulating. The system adopts online mixing modification, directly saves a modification production line, reduces intermediate processes and greatly reduces the cost; the market competitiveness is strong; meanwhile, the online modification has short melt line, short residence time, difficult thermal decomposition and good product quality; meanwhile, the system has good compatibility, can produce products with different characteristics, and meets different downstream customers. PBAT belongs to a small amount of products, and once the market is saturated, other products can be immediately produced; the system can produce various high polymer materials, can be used for producing various products such as PET/PBT/PBS/PBSA and the like, and can be quickly adapted to market change. Taking PBT as an example, products with different viscosities can be produced, and engineering plastic grade PBT and fiber grade PBT can be produced.
Pressure transmitters are respectively arranged at the tops of the esterification kettle 3-1, the esterification kettle 3-2 and the esterification secondary reaction kettle 4, gas phase ports at the tops of the esterification kettle 3-1, the esterification kettle 3-2 and the esterification secondary reaction kettle 4 are respectively connected with a gas inlet of the process tower 5 through respective vacuum regulating valves, and the opening degree of each vacuum regulating valve is respectively controlled by the pressure in the kettle measured by the corresponding pressure transmitter; the gas phase port at the top of the process tower 5 is connected with the medium inlet of an overhead condenser 5a, the medium outlet of the overhead condenser 5a is connected with the inlet of an overhead receiving tank 5b, the bottom outlet of the overhead receiving tank 5b is connected with the reflux port at the upper part of the process tower 5, the overflow port of the overhead receiving tank 5b is connected with a tetrahydrofuran recovery device 19, the gas phase outlet of the overhead condenser 5a is connected with the extraction port of a mechanical vacuum pump 16 through a vacuum regulating valve four JV4, the opening degree of the vacuum regulating valve four JV4 is controlled by the pressure measured by a pressure transmitter four E4, and the pressure transmitter four E4 is arranged at the gas phase outlet of the overhead condenser 5a.
The esterification kettle 3-1, the esterification kettle 3-2 and the esterification secondary reaction kettle 4 share one process tower 5, the top of the esterification kettle A is provided with a pressure transmitter I E1, a gas phase port of the esterification kettle A is connected with a gas inlet of the process tower 5 through a vacuum regulating valve I JV1, and the opening degree of the vacuum regulating valve I JV1 is controlled by the pressure in the esterification kettle A measured by the pressure transmitter I E1; the top of the T esterification kettle is provided with a second pressure transmitter E2, a gas phase port of the T esterification kettle is connected with a gas inlet of the process tower 5 through a second vacuum regulating valve JV2, and the opening degree of the second vacuum regulating valve JV2 is controlled by the pressure in the T esterification kettle measured by the second pressure transmitter E2; the top of the second esterification reaction kettle 4 is provided with a pressure transmitter III E3, a gas phase port of the second esterification reaction kettle 4 is connected with a gas inlet of the process tower 5 through a vacuum regulating valve III JV3, and the opening degree of the vacuum regulating valve III JV3 is controlled by the pressure in the second esterification reaction kettle 4 measured by the pressure transmitter III E3.
The esterification reaction generates ester, higher molecular oligomer, water and BDO to generate tetrahydrofuran by cyclization at high temperature. The water and Tetrahydrofuran (THF) generated in the esterification process enter a process tower 5 for rectification, the bottom of the process tower 5 is heated by liquid heating medium, the recovered BDO discharged from the bottom of the tower is sent back to a reflux port of an esterification kettle, the water and the THF evaporated from the top of the tower are condensed by a tower top condenser 5a and then enter a tower top receiving tank 5b, one part of the water and the THF are used as reflux of the process tower 5, and the rest part of the water and the THF enter a tetrahydrofuran recovery device 19. Because the tail gas quantity of the tower top condenser 5a is small, the vacuum degree requirement can be met by utilizing the mechanical vacuum pump 16 of the subsequent polycondensation, and the system cancels an independent liquid ring pump set, thereby not only saving the investment, but also reducing the consumption of water resources and the treatment and discharge of pollutants.
As shown in fig. 3 to 6, the top of the esterification kettle a and the esterification kettle T are provided with an esterification kettle slurry inlet 3a, an esterification kettle gas phase port 3b, an esterification kettle stirring port 3c and an esterification kettle return port 3k, the centers of the bottoms of the esterification kettle a and the esterification kettle T are respectively connected with a catalyst feed pipe G2, the inner cavities of the two esterification reaction kettles are divided into an esterification kettle outer chamber and an esterification kettle inner chamber by an esterification kettle annular baffle 3f, an esterification kettle discharge port 3d is located at the bottom of the esterification kettle outer chamber, the center of the lower part of the esterification kettle inner chamber is provided with an esterification kettle inner cylinder 3j, and an esterification kettle heating array pipe 3h is distributed in the annular space at the periphery of the esterification kettle inner cylinder 3 j; a nitrogen ring blowing pipe 3n is arranged below the esterification kettle inner cylinder 3j, the radius of the nitrogen ring blowing pipe 3n is smaller than that of the esterification kettle inner cylinder 3j, the nitrogen ring blowing pipe and the esterification kettle inner cylinder are coaxial, spray holes blowing to the kettle bottom are uniformly distributed along the circumference of the lower part of the nitrogen ring blowing pipe 3n, and a gas source pipeline of the nitrogen ring blowing pipe 3n penetrates through the esterification kettle heating tube array 3h and upwards extends out of the top of the esterification reaction kettle.
The catalyst tetrabutyl titanate is easy to hydrolyze when meeting water, so the catalyst inlet 3e is arranged at the bottom of the kettle, and the catalyst is prevented from contacting with water as much as possible; because the esterification reaction can generate a large amount of water in the esterification reaction kettle, the density of the water is low; set up round nitrogen ring blowpipe 3n above catalyst entry 3e, utilize nitrogen partial pressure, in time the desorption moisture, play the bubbling stirring effect simultaneously, make the catalyst that gets into in the cauldron mix with the ester fast for the dissolving rate of catalyst in the ester, avoid contacting with water, reduce the use amount of catalyst.
Be equipped with on the circumference of esterification kettle annular baffle 3f along vertical extension's ejection of compact seam 3f1, be equipped with esterification kettle discharge baffle 3g between esterification kettle annular baffle 3f and the esterification kettle inner wall, ejection of compact seam 3f1 and esterification kettle discharge gate 3d are located the both sides of esterification kettle discharge baffle 3g respectively. The material enters the outer space of the esterification kettle annular baffle 3f from the discharge slot 3f1, flows for a circle along the circumference, and flows out from the discharge hole 3d of the esterification kettle, so that the retention time of the material in the esterification reaction kettle can be prolonged.
As shown in fig. 2, esterification kettle jackets 3m are arranged at the peripheries of the bottoms and the upper parts of the two esterification reaction kettles, a high-temperature heat medium supply pipe S1 is connected with an inlet pipe of an esterification kettle heat medium pump B4 through a high-temperature heat medium feed regulating valve V8, an outlet pipe of an esterification kettle heat medium pump B4 is connected with an esterification kettle column pipe heat medium inlet 3h1 at the lower part of an esterification kettle heating column pipe 3h and an esterification kettle jacket heat medium inlet 3m1 at the lower part of the esterification kettle jacket 3m, and an esterification kettle column pipe heat medium outlet 3h2 at the upper part of the esterification kettle heating column pipe 3h and an esterification kettle jacket heat medium outlet 3m2 at the upper part of the esterification kettle jacket 3m are connected with a high-temperature heat medium return pipe S2 through a high-temperature heat medium; an esterification material temperature transmitter T1 for detecting the temperature of the material is arranged at the bottom of the esterification reaction kettle, and a signal line of the esterification material temperature transmitter T1 is in signal connection with the material temperature control unit; an outlet pipe of the esterification kettle heat medium pump B4 is provided with an esterification heat medium temperature transmitter T2 for detecting the temperature of the heat medium, and a signal wire of the esterification heat medium temperature transmitter T2 is connected with a heat medium temperature control unit; the heating medium temperature control unit is controlled by the temperature signal of the material temperature control unit, and the opening degrees of the heating medium adjusting valve and the high-temperature heating medium feeding adjusting valve V8 are controlled by the temperature signal of the heating medium temperature control unit.
When the esterification reaction kettle needs to be heated, the high-temperature heat medium feed regulating valve V8 and the high-temperature heat medium return valve V9 are opened, high-temperature heat conducting oil is sent into an esterification kettle heating array pipe 3h and an esterification kettle jacket 3m by an esterification kettle heat medium pump B4, and after the materials are heated, the materials flow out of a high-temperature heat medium return pipe S2 through the high-temperature heat medium return valve V9. According to the temperature required by the esterification reaction kettle, the temperature of the heating medium entering the heating tube 3h of the esterification kettle and the temperature of the heating medium entering the jacket 3m of the esterification kettle can be accurately adjusted, and the opening degree of the high-temperature heating medium feeding adjusting valve V8 is accurately controlled according to the temperature requirement of the heating medium, so that the temperature of the material in the reaction kettle is strictly changed according to the set temperature rising curve.
The pre-polycondensation reaction kettle 6 comprises an upper pre-polycondensation chamber and a lower pre-polycondensation chamber which are separated by a middle partition plate, the discharge port of the esterification secondary reaction kettle 4 is connected with the feed port of the upper pre-polycondensation chamber, the discharge port of the upper pre-polycondensation chamber is connected with the feed port of the lower pre-polycondensation chamber through a communication elbow, and the discharge port of the lower pre-polycondensation chamber is connected with the feed port of the final polycondensation reaction kettle 7. The pre-polycondensation reaction kettle 6 adopts an upper chamber and a lower chamber, materials in the upper chamber react to a certain degree of polymerization, and enter the lower chamber through a potential difference to perform further polycondensation reaction. The combination of two reaction forms of plug flow and full mixing is realized, the one-time investment cost is saved, and the efficiency of the reactor is improved.
The gas phase port of the pre-polycondensation reaction kettle 6 is connected with the gas inlet of the first scraper condenser 11-1, the gas phase port of the final polycondensation reaction kettle 7 is connected with the gas inlet of the second scraper condenser 11-2, and the gas phase port of the tackifying reaction kettle 8 is connected with the gas inlet of the third scraper condenser 11-3. The bottom liquid discharge ports of the scraper condensers are respectively connected with corresponding hot wells 12 through atmosphere legs 11a, and the discharged liquid at the outlets of the hot wells is pumped out by a circulating pump, cooled by a cooler and then returned to the upper parts of the scraper condensers for circulating spraying.
As shown in fig. 7, taking a scraper condenser as an example, the first outlet of each hot well 12 is connected to the inlet of a first filter L1 through a hot well outlet valve V1a, the outlet of a first filter L1 is connected to the inlet of a first circulation pump B1, the outlet of a first circulation pump B1 is connected to the inlet of a first cooler C1, the outlet of the first cooler C1 is connected to a first circulation pipe G3a, the outlet of the circulation pipe G3a is connected to a first spray valve V2a and a first return valve V3a, respectively, the outlet of the first spray valve V2a is connected to a first spray port at the upper part of the scraper condenser, the outlet of the first return valve V3a is connected to the top return port of the lye tank 14 through a BDR return pipe G4, the bottom of the lye tank 14 is connected to a lye outlet pipe G5, and the lye outlet pipe G5 is connected to the inlet of the first filter L1 through a first cleaning valve V4 58; the second outlet of the hot well is connected with the inlet of a second filter L2 through a second hot well outlet valve V1B, the outlet of a second filter L2 is connected with the inlet of a second circulating pump B2, the outlet of the second circulating pump B2 is connected with the inlet of a second cooler C2, the outlet of the second cooler C2 is connected with a second circulating pipe G3B, the outlet of the second circulating pipe G3B is respectively connected with a second spraying valve V2B and a second return valve V3B, the outlet of the second spraying valve V2B is connected with the second spraying port at the upper part of the scraper condenser, the outlet of the second return valve V3B is connected with a BDR return pipe G4, and an alkali liquor tank outlet pipe G5 is connected with the inlet of the second filter L2 through a second cleaning valve V4B.
Each scraper condenser is provided with two circulating spraying lines which are used for standby, a first hot well outlet valve V1a and a first spraying valve V2a are opened, a second hot well outlet valve V1B and a first backflow valve V3a are closed, discharged liquid of the scraper condenser enters an inner chamber of a hot well through an atmosphere leg 11a, enters an outer chamber of the hot well after being filtered, and is extracted from a first hot well outlet valve V1a through a first circulating pump B1, is filtered by a first filter L1, is cooled by a first cooler C1 and then enters the upper part of the scraper condenser through a first circulating pipe G3a and a first spraying valve V2a for spraying; after the process steam generated by the polycondensation reaction enters the scraper condenser from the polycondensation gas phase pipe, most BDO and entrained oligomer micromolecules are condensed by liquid phase spraying, and the uncaptured process gas is discharged from the top of the scraper condenser and is pumped out. Due to the side reactions of the PBAT polycondensation reaction and the formation of a lot of oligomers, the first circulation spray line will clog up after a period of operation. At the moment, the first hot well outlet valve V1a and the first spray valve V2a are closed, the second hot well outlet valve V1b and the second spray valve V2b are opened, and the second circulating spray line is directly switched on without stopping the vehicle, so that the vacuum degree of the PBAT production line is maintained to be not fluctuated, and continuous and stable production is ensured. Simultaneously, a first cleaning valve V4a and a first reflux valve V3a are opened, alkali liquor in the alkali liquor tank 14 enters a first circulating pump B1 through an alkali liquor tank outlet pipe G5 and a first filter L1, the first circulating pump B1 sends the alkali liquor into a first cooler C1 and a first circulating pipe G3a, the alkali liquor returns to the alkali liquor tank 14 through the first reflux valve V3a and a BDR reflux pipe G4, the alkali liquor tank 14 can be supplemented with the alkali liquor through an alkali liquor supply pipe G11, oligomer is effectively dissolved by the alkali liquor, pipelines are cleaned on line and blocked, the cleaning process is pollution-free, the production process is not stopped, the system stability is good, and continuous production is guaranteed.
The upper part and the lower part of the atmosphere leg 11a are respectively connected with a nitrogen pipe G12 through a nitrogen valve V6, the upper position and the lower position of the atmosphere leg 11a are respectively connected with a nitrogen pipe G12, and the nitrogen valve V6 is opened at regular time, so that high-pressure nitrogen enters the atmosphere leg to form pulse impact, and the blockage of the atmosphere leg can be effectively avoided.
And a third outlet of the hot well is connected with the cleaning box 13, a first discharge valve V5a is installed on an outlet pipeline of the first circulating pump, and a second discharge valve V5b is installed on an outlet pipeline of the second circulating pump. Opening a first discharge valve V5a to barrele the impurities output by the first circulating pump; open two V5b of discharge valve in the same way, can make the cleanliness factor of system higher with the impurity barrelling of two exports of circulating pump, it is more stable to operate.
The top exhaust port of the third scraper condenser 11-3 is connected with the suction port of a first-stage steam jet pump P1, the top exhaust port of the second scraper condenser 11-2 is connected with the suction port of a second-stage steam jet pump P2, the top exhaust port of the first scraper condenser 11-1 is connected with the suction port of a fourth-stage steam jet pump P4, the outlets of the first-stage steam jet pump P1 and the second-stage steam jet pump P2 are connected with the air inlet of a first condensing tank J1, the exhaust port of the first condensing tank J1 is connected with the suction port of a third-stage steam jet pump P3, the outlets of the third-stage steam jet pump P3 and the fourth-stage steam jet pump P4 are connected with the air inlet of a second condensing tank J2, the exhaust port of the second condensing tank J2 is connected with the suction port of a fifth-stage steam jet pump P5, the outlet of the fifth-stage steam jet pump P5 is connected with the air inlet of a third condensing tank J3, the exhaust port of a third condensing, an exhaust port of the six-stage steam jet pump P6 is connected with an upper air inlet of the vacuum condenser 15, a lower exhaust port of the vacuum condenser 15 is connected with an inlet of the mechanical vacuum pump 16 through a vacuum-pumping pipe G10, and an outlet of the mechanical vacuum pump 16 is connected with a middle inlet of the gas-liquid separation tank 17; the top outlet of the gas-liquid separation tank 17 is connected with a heat medium furnace 18; the bottom outlet of the gas-liquid separation tank 17 is connected with a tetrahydrofuran recovery device 19.
The suction force required by the gas phase port of the tackifying reaction kettle is greater than that of the gas phase port of the final polycondensation reaction kettle, and the suction force required by the gas phase port of the final polycondensation reaction kettle is greater than that of the gas phase port of the pre-polycondensation reaction kettle, so that the gas phase port of the tackifying reaction kettle is connected with a first-stage steam jet pump P1, and the gas phase port of the pre-polycondensation reaction kettle is connected with a fourth-stage steam jet pump P4; the exhaust gas of a third scraper condenser 11-3 of a tackifying section is pumped out by a first-stage steam jet pump P1, the exhaust gas of a second scraper condenser 11-2 of a final condensation section is pumped out by a second-stage steam jet pump P2, the first-stage and the second-stage enter a first condensation tank J1 together for condensation, the exhaust gas of the first condensation tank J1 is pumped out by a third-stage steam jet pump P3, the exhaust gas of a first scraper condenser 11-1 of a pre-condensation section is pumped out by a fourth-stage steam jet pump P4, the third-stage and the fourth-stage enter a second condensation tank J2 together for condensation, the exhaust gas of the second condensation tank J2 is pumped out by a fifth-stage steam jet pump P5 and then enters a third condensation tank J3 for condensation, the exhaust gas of the third condensation tank J3 is pumped out by a sixth-stage steam jet pump P6 and enters a pipe pass of a vacuum condenser 15 for condensation, a circulating spray mode is adopted to capture BDO and oligomer in process steam, zero waste discharge guarantees the stable operation of vacuum system.
The shell pass of the vacuum condenser 15 uses chilled water for indirect condensation, so that water generated by BDO cyclization can be effectively condensed, the subsequent vacuum pressure is reduced, a smaller mechanical vacuum pump 16 can be selected, and the investment is reduced. BDO is easy to generate cyclization reaction to generate tetrahydrofuran which is a low-boiling-point substance and is difficult to capture, and the tetrahydrofuran is easy to accumulate in a liquid ring vacuum pump set to cause the reduction of the vacuum degree of the system. A gas-liquid separator is added at the rear end of the mechanical vacuum pump 16, the condensate enters a tetrahydrofuran recovery device 19 for recycling, and the non-condensable gas enters a heating medium furnace 18 for use as fuel, so that the environment is protected, and the energy consumption is reduced.
The power ports of all stages of steam jet pumps are connected with a BDO steam pipe G6, the tube pass inlet of a vacuum condenser 15 and the top spray port of each stage of condensing tank are connected with a cold BDO pipe G7, the bottom liquid discharge port of each stage of condensing tank is connected with a condensing tank liquid discharge pipe G8, the lower end of each condensing tank liquid discharge pipe G8 is inserted into a vacuum liquid seal tank J4, the bottom liquid discharge port of the vacuum liquid seal tank J4 is connected with the inlet of a vacuum liquid seal tank circulating pump B3, the outlet of the vacuum liquid seal tank circulating pump B3 is connected with the inlet of a vacuum system cooler C3, and the outlet of the vacuum system cooler C3 is connected with the cold BDO pipe G7; the tube pass outlet of the vacuum condenser 15 is connected with a condenser discharge pipe G9, the overflow pipes of the condenser discharge pipe G9, the vacuum liquid seal tank J4 and the overflow pipes of the thermal wells are respectively connected with a BDR low-level tank J5, the liquid discharge port at the bottom of the BDR low-level tank J5 is connected with the inlet of a BDR delivery pump, and the outlet of the BDR delivery pump is connected with the return port in the middle of the process tower 5 and a BDO feed pipe G1 through a BDR return pipe G4.
BDO steam pipes G6 provide power for each steam jet pump, cold BDO sprays in each stage of condensing tanks to capture BDO and oligomers in process steam generated by polycondensation, spray liquid enters a vacuum liquid seal tank J4 through each condensing tank liquid discharge pipe G8 to be collected, BDO on the right side in the vacuum liquid seal tank J4 is pumped out by a vacuum liquid seal tank circulating pump B3, is cooled by a vacuum system cooler C3 and is sent into a cold BDO pipe G7 to be sprayed circularly. The vacuum liquid seal tank J4 and BDO overflowed from each hot well all enter a BDR low-level tank J5 to be collected, the BDR delivery pump sends the recovered 1, 4-butanediol back to the slurry mixing tank I1 a, the slurry mixing tank II 1b and the process tower 5 through a BDR delivery pipe G13 for recycling, and the complete recycling of BDR materials is realized.
The suction port of the primary steam jet pump P1 is also connected with a BDO steam pipe G6 through a vacuum adjusting valve seven JV7, the opening degree of the vacuum adjusting valve seven JV7 is controlled by a pressure signal measured by a pressure transmitter seven E7, and a pressure transmitter seven E7 is arranged at the top of the tackifying reaction kettle 8; the suction port of the secondary steam jet pump P2 is also connected with a BDO steam pipe G6 through a vacuum adjusting valve six JV6, the opening degree of the vacuum adjusting valve six JV6 is controlled by a pressure signal measured by a pressure transmitter six E6, and the pressure transmitter six E6 is installed at the top of the final polycondensation reaction kettle 7; the suction port of the four-stage steam jet pump P4 is also connected with a BDO steam pipe G6 through a vacuum adjusting valve five JV5, the opening degree of the vacuum adjusting valve five JV5 is controlled by a pressure signal measured by a pressure transmitter five E5, and the pressure transmitter five E5 is arranged at the top of the pre-polycondensation reaction kettle 6; the shell side inlet of the vacuum condenser 15 is connected with a refrigerant water supply pipe S3, the shell side outlet of the vacuum condenser 15 is connected with a refrigerant water return pipe S4 through a refrigerant water regulating valve V7, the opening degree of the refrigerant water regulating valve V7 is controlled by the temperature of a vacuumizing pipe G10 measured by a vacuumizing pipe temperature transmitter T3, the rotating speed of the mechanical vacuum pump 16 is controlled by a pressure signal measured by a pressure transmitter eight E8, and the pressure transmitter eight E8 is installed on the vacuumizing pipe G10.
When the pressure in the tackifying reaction kettle 8 is low, the vacuum adjusting valve seven JV7 is opened or the opening degree thereof is increased, and when the pressure in the tackifying reaction kettle 8 is high, the vacuum adjusting valve seven JV7 is closed or the opening degree thereof is decreased; when the pressure in the final polycondensation reaction vessel 7 is low, the vacuum adjusting valve six JV6 is opened or the opening degree thereof is increased, and when the pressure in the final polycondensation reaction vessel 7 is high, the vacuum adjusting valve six JV6 is closed or the opening degree thereof is decreased; when the pressure in the pre-polycondensation reaction kettle 6 is low, opening the vacuum adjusting valve five JV5 or increasing the opening of the vacuum adjusting valve five JV5, and when the pressure in the pre-polycondensation reaction kettle 6 is high, closing the vacuum adjusting valve five JV5 or reducing the opening of the vacuum adjusting valve five JV 5; the vacuum degree of each kettle is adjusted by the BDO steam, the caliber of each vacuum adjusting valve can be greatly reduced, the purchase cost is greatly saved, and the installation is convenient. When the pressure of the vacuumizing pipe G10 is higher, the rotating speed of the mechanical vacuum pump 16 is increased; when the pressure of the vacuum pumping pipe G10 is lower, the rotating speed of the mechanical vacuum pump 16 is reduced; when the temperature of the vacuumizing pipe G10 is higher, the opening degree of the chilled water regulating valve V7 is increased; when the temperature of the vacuum tube G10 is lower, the opening degree of the chilled water regulating valve V7 is reduced.
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, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of 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 (8)

1.A production system of biodegradable polyester comprises an esterification reaction kettle, a pre-polycondensation reaction kettle and a final polycondensation reaction kettle, and is characterized in that: the esterification reaction kettle comprises an esterification kettle A, an esterification kettle T and an esterification reaction kettle II, wherein a slurry inlet at the top of the esterification kettle A is connected with a discharge hole of a slurry finished product tank I, a top inlet of the slurry finished product tank I is connected with a discharge hole of a slurry mixing tank I, and the top of the slurry mixing tank I is connected with a BDO feed pipe and is provided with a PTA feed port; a slurry inlet at the top of the T esterification kettle is connected with a discharge hole of a slurry finished product tank II, a top inlet of the slurry finished product tank II is connected with a discharge hole of a slurry mixing tank II, and the top of the slurry mixing tank II is connected with a BDO feed pipe and is provided with an AA feed port; the discharge ports of the esterification kettle A and the esterification kettle T are respectively connected with the feed port of the esterification reaction kettle, the discharge port of the esterification reaction kettle is connected with the feed port of the pre-polycondensation reaction kettle, the discharge port of the pre-polycondensation reaction kettle is connected with the feed port of the final polycondensation reaction kettle, and the discharge port of the final polycondensation reaction kettle is connected with the feed port of the tackifying reaction kettle.
2. The system for producing biodegradable polyester according to claim 1, wherein: the discharge port of the tackifying reaction kettle is connected with the screw extruder through a metering pump, the inlet end of the screw extruder is also provided with a modified material inlet, and the discharge port of the screw extruder is connected with the pelletizing system.
3. The system for producing biodegradable polyester according to claim 1, wherein: the top parts of the esterification kettle A, the esterification kettle T and the esterification secondary reaction kettle are respectively provided with a pressure transmitter, gas phase ports at the top parts of the esterification kettle A, the esterification kettle T and the esterification secondary reaction kettle are respectively connected with a gas inlet of the process tower through respective vacuum regulating valves, and the opening degree of each vacuum regulating valve is respectively controlled by the pressure in the kettle measured by the corresponding pressure transmitter; the gas phase outlet of the tower top condenser is connected with the gas phase outlet of the tower top condenser, the bottom outlet of the tower top receiving tank is connected with the reflux port at the upper part of the process tower, the overflow port of the tower top receiving tank is connected with the tetrahydrofuran recovery device, the gas phase outlet of the tower top condenser is connected with the extraction port of the mechanical vacuum pump through a vacuum regulating valve IV, the opening degree of the vacuum regulating valve IV is controlled by the pressure measured by a pressure transmitter IV, and the pressure transmitter IV is arranged at the gas phase outlet of the tower top condenser.
4. The system for producing biodegradable polyester according to claim 1, wherein: the bottom centers of the esterification kettle A and the esterification kettle T are respectively connected with a catalyst feeding pipe, the inner cavities of the two esterification reaction kettles are divided into an esterification kettle outer chamber and an esterification kettle inner chamber by an esterification kettle annular baffle plate, a discharge hole of the esterification kettle is positioned at the bottom of the esterification kettle outer chamber, the center of the lower part of the esterification kettle inner chamber is provided with an esterification kettle inner cylinder, and an esterification kettle heating array pipe is distributed in an annular space at the periphery of the esterification kettle inner cylinder; and a nitrogen ring blowing pipe is arranged below the inner cylinder of the esterification kettle, the radius of the nitrogen ring blowing pipe is smaller than that of the inner cylinder of the esterification kettle, the nitrogen ring blowing pipe and the inner cylinder of the esterification kettle share the same axis, spray holes blowing to the bottom of the kettle are uniformly distributed along the circumference of the lower part of the nitrogen ring blowing pipe, and an air source pipeline of the nitrogen ring blowing pipe penetrates through the heating tube array of the esterification kettle and upwards extends out of the top of the esterification reaction kettle.
5. The system for producing biodegradable polyester according to claim 1, wherein: the pre-polycondensation reaction kettle comprises an upper pre-polycondensation chamber and a lower pre-polycondensation chamber which are separated by a middle partition plate, the discharge port of the esterification reaction kettle is connected with the feed port of the upper pre-polycondensation chamber, the discharge port of the upper pre-polycondensation chamber is connected with the feed port of the lower pre-polycondensation chamber through a communication elbow pipe, and the discharge port of the lower pre-polycondensation chamber is connected with the feed port of the final polycondensation reaction kettle.
6. The system for producing biodegradable polyester according to claim 3, wherein: the gas phase port of the pre-polycondensation reaction kettle is connected with the gas inlet of the first scraper condenser, the gas phase port of the final polycondensation reaction kettle is connected with the gas inlet of the second scraper condenser, the gas phase port of the tackifying reaction kettle is connected with the gas inlet of the third scraper condenser, the bottom liquid discharge port of each scraper condenser is respectively connected with the corresponding hot well through an atmospheric leg, the first outlet of each hot well is connected with the inlet of the first filter through the first hot well outlet valve, the outlet of the first filter is connected with the inlet of the first circulating pump, the outlet of the first circulating pump is connected with the inlet of the first cooler, the outlet of the first cooler is connected with the first circulating pipe, the outlet of the first circulating pipe is respectively connected with the first spray valve and the first reflux valve, the outlet of the first spray valve is connected with the first spray port at the upper part of the first scraper condenser, the outlet of the first reflux valve is connected with the top, the bottom of the lye tank is connected with a lye tank outlet pipe, and the lye tank outlet pipe is connected with an inlet of the first filter through a first cleaning valve; the second outlet of the hot well is connected with the inlet of the second filter through a second hot well outlet valve, the outlet of the second filter is connected with the inlet of a second circulating pump, the outlet of the second circulating pump is connected with the inlet of a second cooler, the outlet of the second cooler is connected with a second circulating pipe, the outlet of the second circulating pipe is respectively connected with a second spray valve and a second return valve, the outlet of the second spray valve is connected with a second spray port on the upper part of the scraper condenser, the outlet of the second return valve is connected with the BDR return pipe, and the outlet pipe of the alkaline solution tank is connected with the inlet of the second filter through a second cleaning valve.
7. The system for producing biodegradable polyester according to claim 6, wherein: the top exhaust port of the third scraper condenser is connected with the suction port of the first-stage steam jet pump, the top exhaust port of the second scraper condenser is connected with the suction port of the second-stage steam jet pump, the top exhaust port of the first scraper condenser is connected with the suction port of the fourth-stage steam jet pump, the outlets of the first-stage steam jet pump and the second-stage steam jet pump are connected with the air inlet of the first condensing tank, the exhaust port of the first condensing tank is connected with the suction port of the third-stage steam jet pump, the outlets of the third-stage steam jet pump and the fourth-stage steam jet pump are connected with the air inlet of the second condensing tank, the exhaust port of the second condensing tank is connected with the suction port of the fifth-stage steam jet pump, the outlet of the fifth-stage steam jet pump is connected with the air inlet of the third condensing tank, the exhaust port of the third condensing tank is connected with the suction port of the, an exhaust port at the lower part of the vacuum condenser is connected with an inlet of the mechanical vacuum pump through a vacuum-pumping pipe, and an outlet of the mechanical vacuum pump is connected with a middle inlet of the gas-liquid separation tank; the top outlet of the gas-liquid separation tank is connected with the heating medium furnace; and the bottom outlet of the gas-liquid separation tank is connected with the tetrahydrofuran recovery device.
8. The system for producing biodegradable polyester according to claim 7, wherein: the power ports of all stages of steam jet pumps are connected with a BDO steam pipe, the tube pass inlet of the vacuum condenser and the top spray port of all stages of condensing tanks are connected with a cold BDO pipe, the bottom liquid discharge port of each stage of condensing tank is connected with a condensing tank liquid discharge pipe, the lower end of each condensing tank liquid discharge pipe is inserted into a vacuum liquid seal tank, the bottom liquid discharge port of the vacuum liquid seal tank is connected with the inlet of a circulating pump of the vacuum liquid seal tank, the outlet of the circulating pump of the vacuum liquid seal tank is connected with the inlet of a cooler of a vacuum system, and the outlet of the cooler of the vacuum system is connected with the cold BDO pipe; the tube pass outlet of the vacuum condenser is connected with a condenser discharge pipe, overflow pipes of the condenser discharge pipe, the vacuum liquid seal tank and overflow pipes of the thermal wells are respectively connected with the BDR low-level tank, a liquid discharge port at the bottom of the BDR low-level tank is connected with an inlet of the BDR delivery pump, and an outlet of the BDR delivery pump is connected with a return port in the middle of the process tower and the BDO feeding pipe through a BDR return pipe.
CN202020717946.0U 2020-05-06 2020-05-06 Production system of biodegradable polyester Active CN212560068U (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111440301A (en) * 2020-05-06 2020-07-24 扬州惠通化工科技股份有限公司 Multifunctional polyester continuous production system
CN113522198A (en) * 2021-08-16 2021-10-22 华峰集团上海工程有限公司 Esterification device and method for PTA and BDO in PBAT production process
WO2021244193A1 (en) * 2020-06-01 2021-12-09 欧瑞康巴马格惠通（扬州）工程有限公司 System for producing pbs-based biodegradable material
CN115746282A (en) * 2022-10-28 2023-03-07 浙江长鸿生物材料有限公司 Flexible switching production process of PBAT (poly (butylene adipate-co-terephthalate)) and PBT (polybutylene terephthalate) products
WO2023039923A1 (en) 2021-09-14 2023-03-23 珠海万通化工有限公司 Semi-aromatic polyester, and preparation method therefor and application thereof
WO2023040768A1 (en) 2021-09-14 2023-03-23 珠海万通化工有限公司 Polyester, and preparation method therefor and application thereof

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111440301A (en) * 2020-05-06 2020-07-24 扬州惠通化工科技股份有限公司 Multifunctional polyester continuous production system
CN111440301B (en) * 2020-05-06 2023-10-31 扬州惠通科技股份有限公司 Multifunctional polyester continuous production system
WO2021244193A1 (en) * 2020-06-01 2021-12-09 欧瑞康巴马格惠通（扬州）工程有限公司 System for producing pbs-based biodegradable material
CN113522198A (en) * 2021-08-16 2021-10-22 华峰集团上海工程有限公司 Esterification device and method for PTA and BDO in PBAT production process
WO2023039923A1 (en) 2021-09-14 2023-03-23 珠海万通化工有限公司 Semi-aromatic polyester, and preparation method therefor and application thereof
WO2023040768A1 (en) 2021-09-14 2023-03-23 珠海万通化工有限公司 Polyester, and preparation method therefor and application thereof
CN115746282A (en) * 2022-10-28 2023-03-07 浙江长鸿生物材料有限公司 Flexible switching production process of PBAT (poly (butylene adipate-co-terephthalate)) and PBT (polybutylene terephthalate) products

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