CN113813866A

CN113813866A - Flexible production system of polyester products

Info

Publication number: CN113813866A
Application number: CN202010563816.0A
Authority: CN
Inventors: 朱昌全
Original assignee: Oerlikon Barmag Huitong Yangzhou Engineering Co Ltd
Current assignee: Oerlikon Barmag Huitong Yangzhou Engineering Co Ltd
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-12-21
Anticipated expiration: 2040-06-19
Also published as: CN113813866B

Abstract

The invention relates to a flexible production system of polyester products, which comprises a first esterification polycondensation line and a second esterification polycondensation line, wherein the first and second esterification polycondensation lines respectively comprise a slurry preparation tank, a first esterification kettle, a second esterification kettle, a pre-polycondensation kettle, a second polycondensation kettle and a final polycondensation kettle which are sequentially connected in series; the first outlet branch of the first line esterification kettle is connected with the feed inlet of the first line esterification kettle, the second outlet branch of the first line esterification kettle is connected with the feed inlet of the second line esterification kettle together with the outlet of the second line esterification kettle, the second line esterification kettle is of a horizontal multi-chamber structure, each chamber is provided with a stirrer and an auxiliary material injection port respectively, and each auxiliary material injection port is connected with an auxiliary material supply pipe respectively. The system can be used for producing traditional polyester products with luster, semi-dull property and the like, and can also be used for producing special products with cation, flame retardance, high shrinkage or bottle flakes and the like.

Description

Flexible production system of polyester products

Technical Field

The invention relates to a polyester production system, in particular to a flexible production system of a polyester product, and belongs to the technical field of chemical equipment.

Background

The existing polyester production system comprises a slurry preparation device, an esterification device, a polycondensation device and the like, only one product can be produced at the same time, and the product is single. If different polymerization products need to be produced, production conversion is needed; when products are converted, the time consumption is long, a large number of isolated products are produced, and the loss is large. The slurry at normal temperature needs to react for about 4 hours at the reaction temperature of 250-260 ℃ in the esterification kettle for a long time.

In traditional slurry configuration, the feed pipes of EG and catalyst are directly welded with the emptying header pipe of the slurry preparation tank, liquid EG and catalyst directly flow into the slurry preparation tank along the wall of the pipeline, the contact area of the EG and catalyst with raw materials such as granular terephthalic acid is small, and the dispersion effect is poor. The liquid Ethylene Glycol (EG) and the catalyst which flow into the slurry preparation tank and are concentrated in a small local area are dispersed into granular terephthalic acid (PTA) or isophthalic acid (IPA) only by forced stirring of a stirrer, so that the dispersion effect is poor, the power consumption is high, and uniform mixing of the slurry is not facilitated. In addition, the PTA dust content in the tail gas discharged by the slurry preparation tank is high, which not only causes raw material loss, but also pollutes the surrounding environment and has potential safety hazard.

The polycondensation device generally comprises a pre-polycondensation kettle, a polycondensation double-kettle, a final polycondensation kettle and a spraying system, wherein the spraying system is used for removing EG and oligomer generated in the polycondensation process, tail gas from the pre-polycondensation kettle is vacuumized by adopting an independent liquid ring vacuum pump after passing through the spraying system, the tail gas from the polycondensation double-kettle and the final polycondensation kettle is respectively connected into a third-stage jet pump and a first-stage jet pump of a vacuum unit after passing through the spraying system, the vacuum of the reaction kettle is adjusted by controlling the flow of balance steam through an adjusting valve, and the final tail gas is pumped out through a shared liquid ring vacuum pump.

The gas phase outlet of each polycondensation kettle is connected with a scraper condenser, the scraper condenser mainly comprises a horizontal cylinder and a vertical cylinder, the vertical cylinder is connected to the upper part of the tail end of the horizontal cylinder, a condensation spray nozzle is arranged in the inner cavity of the vertical cylinder, the condensation spray nozzle is connected with a spray pipe, and a scraper pumping hole is formed in the top of the vertical cylinder; a scraper rotor is arranged in the inner cavity of the horizontal cylinder, the scraper rotor comprises a rotor shaft and a scraper connected to the rotor shaft, the scraper is matched with the inner wall of the horizontal cylinder, a scraper air inlet is arranged at the upper part of the head end of the horizontal cylinder, and a scraper medium outlet is arranged at the lower part of the tail end of the horizontal cylinder; the scraper plate medium outlet is connected with the hot well through an atmosphere leg, an EG outlet at the bottom of the hot well is connected with an inlet of a spraying circulating pump, and an outlet of the spraying circulating pump is connected with a spraying pipe through an EG circulating pipe.

When the device works, the cold liquid EG sprayed out in an umbrella shape from the condensation spray head is contacted with the gaseous EG, one part of the EG can be absorbed, the EG becomes liquid and flows downwards, meanwhile, the oligomer can be collected by the liquid EG and flows downwards into the horizontal cylinder along with the EG, a certain liquid level is kept in the horizontal cylinder, the oligomer adhered to the inner wall of the horizontal cylinder can be scraped by the scraper, finally, the oligomer and the liquid EG are discharged from a scraper medium outlet, the oligomer and the liquid EG enter a hot well through an atmosphere leg pipe and an atmosphere leg, the EG condensate is pumped out by the spraying circulating pump, and the EG returns to the vertical cylinder through the EG circulating pipe and the spraying pipe to be sprayed.

The above structure has the following disadvantages: 1. two sets of liquid ring vacuum pumps are adopted, so that the investment cost is high, and the occupied area is large; 2. because the requirement on the vacuum degree of the polycondensation kettle II is high, the vacuumizing gas speed is high, so that the oligomer is easy to separate out at the inlet of the second-stage semi-injection pump, and the blockage is frequently caused; high-temperature EG or EG steam is required to be adopted for regular flushing, and the vacuum degree fluctuation of the polycondensation two-kettle is caused when the flushing is carried out every time, so that the product quality is influenced.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a flexible production system of polyester products, which can produce traditional polyester products with luster, semi-dull property and the like and can also produce special products with cation, flame retardance, high shrinkage or bottle flakes and the like.

In order to solve the technical problems, the flexible production system of the polyester product comprises a first esterification polycondensation line and a second esterification polycondensation line, wherein the first esterification polycondensation line comprises a first line slurry preparation tank, a first line esterification first kettle, a first line esterification second kettle, a first line pre-polycondensation kettle, a first line polycondensation second kettle and a first line final polycondensation kettle which are sequentially connected in series, a discharge port of the first line final polycondensation kettle is connected with a first line granulator or first line spinning equipment through a first melt delivery pump, the second esterification polycondensation line comprises a second line slurry preparation tank, a second line esterification first kettle, a second line esterification second kettle, a second line pre-polycondensation kettle, a second line polycondensation kettle and a second line final polycondensation kettle which are sequentially connected in series, and a discharge port of the second line final polycondensation kettle is connected with the second line granulator or second line spinning equipment through a second melt delivery pump; the PTA feeding pipe is connected with the top of the first-line slurry preparation tank, and the IPA feeding pipe is connected with the top of the second-line slurry preparation tank; the first esterification material delivery pump is installed at the bottom outlet of the first esterification kettle, the second esterification material delivery pump is installed at the bottom outlet of the first esterification kettle, the first outlet branch of the first esterification material delivery pump is connected with the feed inlet of the first esterification kettle, the second outlet branch of the first esterification material delivery pump is connected with the feed inlet of the second esterification kettle together with the outlet of the second esterification material delivery pump, the second esterification kettle is of a horizontal multi-chamber structure, and each chamber is provided with an agitator and an auxiliary material injection port respectively, and each auxiliary material injection port is connected with an auxiliary material supply pipe respectively.

Compared with the prior art, the invention has the following beneficial effects: EG. The PTA and the catalyst are uniformly stirred in a first-line slurry preparation tank, and can also be subjected to self-circulation through a first slurry conveying pump, and after being uniformly mixed, the mixture is conveyed into a first-line esterification kettle through the first slurry conveying pump to perform esterification reaction; EG. IPA and catalyst are stirred uniformly in the second-line slurry preparation tank, and self-circulation can be carried out through the second slurry delivery pump, and the IPA and the catalyst are delivered into the first second-line esterification kettle for esterification reaction after being uniformly mixed; the esterified material in the first linear esterification kettle is sent out by the first esterified material conveying pump, the first path enters the first linear esterification kettle and the second linear esterification kettle to continue reacting, and after the first linear pre-polycondensation kettle, the first linear polycondensation kettle and the first linear final polycondensation kettle are polycondensed, the first linear pre-polycondensation kettle is sent to a linear granulator to be cut into granules or sent to a linear spinning device to be spun by the first melt conveying pump, and the traditional polyester products with luster and semi-dull degree can be produced. The esterification product of the first second-line esterification kettle is sent out by the second esterification material delivery pump, mixed with the second path of material at the outlet of the first esterification material delivery pump and then enters the second-line esterification kettle, the auxiliary materials of related special varieties can be added into any chamber of the second-line esterification kettle through the auxiliary material supply pipe, the esterification reaction is further carried out under certain pressure, temperature and stirring conditions, after the polycondensation of the second-line pre-polycondensation kettle, the second-line polycondensation kettle and the second-line final polycondensation kettle, the second melt delivery pump is sent to a second-line granulator for granulation or is sent to second-line spinning equipment for spinning, and special products such as cations, flame retardance, high shrinkage or bottle flakes can be produced. The production proportion of the two lines can be flexibly adjusted by only operating one line or operating one line and two lines simultaneously, and the production of conventional products is not influenced and the production change loss is avoided when special products are produced.

As an improvement of the invention, the outlet of the first esterification material conveying pump is also connected with the top circulation port of the first esterification kettle through a first esterification circulation pipe; and the outlet of the second esterification material conveying pump is also connected with the top circulating port of the second-line first esterification kettle through a second esterification circulating pipe. The esterified substance with qualified esterification rate discharged from the first-line esterification kettle returns to the first-line esterification kettle through the first esterified substance delivery pump and the esterification circulating pipe for circulation, so that the reaction speed in the first-line esterification kettle is accelerated, the reaction time of the first-line esterification is shortened, and the materials are more uniform. In the same way, the esterified substance with qualified esterification rate discharged from the first two-line esterification kettle returns to the first two-line esterification kettle for circulation through the second esterified material conveying pump and the second esterification circulating pipe, so that the reaction rate in the first two-line esterification kettle is accelerated, the reaction time of the second-line esterification is shortened, and the material is more uniform.

As a further improvement of the invention, the exhaust ports of the first-line esterification first kettle, the first-line esterification second kettle and the second-line esterification first kettle are connected with the air inlet of the first process tower, the bottom of the first process tower is provided with a first EG reflux pump, and the outlet of the first EG reflux pump is connected with the top reflux ports of the first-line esterification first kettle, the first-line esterification second kettle and the second-line esterification first kettle through EG reflux pipes; and the gas outlet of the second two-line esterification kettle is connected with the gas inlet of the second process tower, the bottom of the second process tower is provided with a second EG reflux pump, and the outlet of the second EG reflux pump is connected with the top reflux port of the second two-line esterification kettle through an EG reflux pipe. EG and water vapor discharged from exhaust ports of the first line esterification kettle, the first line esterification kettle and the second line esterification kettle enter the first process tower to be rectified, and EG at the bottom of the first process tower flows back to the first line esterification kettle, the first line esterification kettle and the second line esterification kettle through the first EG reflux pump. The second-line esterification kettle is added with special materials, so that the second-line esterification kettle is independently matched with the second process tower, and EG and water vapor discharged from the second-line esterification kettle are rectified.

As a further improvement of the invention, a powder inlet at the top of the second-line slurry preparation tank is connected with an IPA feeding pipe, the top of the second-line slurry preparation tank is also provided with a spraying column extending along the vertical direction, 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 reflux port at the top of the second-line slurry preparation tank through a separator material return valve and a powder reflux pipe; an EG spray head and a catalyst spray head are sequentially arranged in an inner cavity of the spray column from top to bottom, the EG spray head is connected with an EG feed pipe, and the catalyst spray head is connected with a catalyst feed pipe; the lower extreme that sprays the post inserts second line thick liquids and prepares jar inner chamber and is connected with the liquid material distributor, the middle section top of liquid material distributor and the lower port that sprays the post link up mutually and use and spray the post axis and follow the radial symmetry extension of second line thick liquids preparation jar as the center, the vertical cross-section of liquid material distributor is the rhombus, and the well lower part at liquid material distributor both ends is equipped with the distributor shrouding respectively, and the top of bipartition distributor shrouding is equipped with triangle-shaped tail gas respectively and exports, the lower extreme of liquid material distributor is equipped with the strip seam shape discharge gate isometric with the liquid material distributor.

The low-temperature EG enters the spraying column from the EG feed pipe and is sprayed downwards from the EG spray head; the high-temperature catalyst enters the spraying column from the catalyst feeding pipe and is sprayed downwards from the catalyst spray head; the catalyst is high in temperature and small in flow, and the EG is low in temperature and large in flow, so that the catalyst spray head is closer to the two-line slurry preparation tank, the EG spray head is arranged above the catalyst spray head, the EG is mixed with a catalyst solution in the downward spraying process and falls into the middle section of the liquid material distributor together, liquid is distributed downwards along the strip-shaped discharge port in the flowing process towards the two ends of the liquid material distributor, and the liquid level in the liquid material distributor is lower than the sealing plate of the distributor; IPA powder falls into the second-line slurry preparation tank from the IPA feed pipe and the powder inlet, and is easier to mix with EG and catalyst which are uniformly distributed along the radius under the action of a preparation tank stirrer, slurry which is uniformly mixed enters the second-line slurry preparation tank from the bottom of the second-line slurry preparation tank, and the second-line slurry preparation tank sends the prepared slurry into the first-line esterification kettle through the slurry output pipe for esterification reaction. Under the suction action of a draught fan, a micro-negative pressure state is kept in the second-line slurry preparation tank, so that IPA powder can be conveniently discharged, the phenomenon that the powder overflows outwards due to positive pressure is avoided, tail gas enters the upper part of an inner cavity of the liquid material distributor from the two triangular tail gas outlets and upwards enters the spraying column, floating IPA powder is sprayed through the catalyst spray head and the EG spray head in two stages in the ascending process, most IPA powder is collected and falls back to the second-line slurry preparation tank, the dust content in the tail gas is reduced, a small amount of IPA powder enters the cyclone separator for separation, IPA powder deposited at the bottom of the cyclone separator accumulates to a certain amount, a material return valve of the separator is opened and returns to the second-line slurry preparation tank through a powder return pipe, the IPA powder can be completely recycled, the loss of raw materials is reduced, the field operation environment is improved, and the environmental pollution is avoided. The first-line slurry preparation tank can adopt a traditional structure and can also adopt the structure the same as the second-line slurry preparation tank, and a powder inlet at the top of the first-line slurry preparation tank is connected with the PTA feeding pipe.

As a further improvement of the invention, the long diagonal line of the liquid distributor extends along a vertical plane where the axis of the spray column is located, and the included angle between the two top surfaces of the liquid distributor is 30 degrees; the larger the distance from the axis of the spraying column is, the wider the slit opening of the strip slit-shaped discharge port is. Powder falling on the top surface of the liquid distributor can easily slide off, and accumulation on the upper surface of the liquid distributor is avoided; the seam just below the spraying column is easier to discharge, and the seam with longer flowing distance is wider, which is beneficial to uniform radial discharge of the slurry preparation tank.

As a further improvement of the present invention, a preparation tank liquid level meter is installed at the bottom of the second-line slurry preparation tank, a rotary feed valve is installed on the IPA feed pipe, an EG flow meter and an EG flow control valve are installed on the EG feed pipe, a catalyst flow meter and a catalyst flow control valve are installed on the catalyst feed pipe, the opening degrees of the EG flow control valve and the catalyst flow control valve are both controlled by the flow of the rotary feed valve, and the flow of the rotary feed valve is controlled by the second-line slurry preparation tank liquid level measured by the preparation tank liquid level meter. When the flow rate of IPA is increased, the opening degrees of the EG flow control valve and the catalyst flow control valve are increased proportionally, so that the accurate molar ratio of EG, catalyst and IPA can be kept, and the preparation quality of the slurry is higher.

As a further improvement of the invention, a gas phase outlet of the two-wire pre-polycondensation kettle is connected with a gas inlet of a first scraper condenser, a gas phase outlet of the two-wire pre-polycondensation kettle is connected with a gas inlet of a second scraper condenser, a gas phase outlet of the two-wire final polycondensation kettle is connected with a gas inlet of a third scraper condenser, a top exhaust port of the third scraper condenser is connected with a suction port of a first-stage steam jet pump through a first-stage vacuum-pumping pipe, a top exhaust port of the second scraper condenser is connected with a suction port of a second-stage semi-steam jet pump through a second-stage vacuum-pumping pipe, a top exhaust port of the first scraper condenser is connected with a suction port of a liquid ring pump through a third-stage vacuum-pumping pipe and a vacuum regulating valve, an outlet of the first-stage steam jet pump is connected with a gas inlet of a first-stage spray tank, an exhaust port of the first-stage spray tank is connected with a suction port of the second-stage steam jet pump, and outlets of the second-stage semi-steam jet pump are both connected with a gas inlet of the second-stage spray tank, an exhaust port of the second-stage spraying tank is connected with a suction port of the third-stage steam jet pump, an outlet of the third-stage steam jet pump is connected with an air inlet of the third-stage spraying tank, and an exhaust port of the third-stage spraying tank is connected with a suction port of the liquid ring pump; and the top exhaust port of the second scraper condenser is also connected with the first-stage spray tank through a second-stage auxiliary vacuum tube, EG circular tubes are arranged on the inner wall of the second-stage auxiliary vacuum tube at intervals of a certain distance, nozzles are uniformly distributed on the circumference of the EG circular tubes, and each EG circular tube is connected with an EG circulating tube of the second scraper condenser. The vacuum requirement of the second-line prepolycondensation kettle is not high, generally 8-15 KPa (A), the vacuum of the inlet of the liquid ring pump behind the vacuum jet unit can be controlled at 5-20 KPa, and the vacuum requirement of the second-line prepolycondensation kettle can be met, therefore, the exhaust port of the first scraper condenser is directly connected with the liquid ring pump behind the vacuum jet unit through the regulating valve, the original independent liquid ring pump of the second-line prepolycondensation kettle is cancelled, and the equipment investment cost and the occupation of the workshop area are reduced. The vacuum of the second kettle of the second wire polycondensation is generally 0.8-1.5 KPa (A), the vacuum of the first-stage spraying tank is below 0.8KPa (A), the exhaust port of the second scraper condenser is additionally provided with a second-stage auxiliary vacuum pipe which is connected with the first-stage spraying tank, the second-stage vacuum pipe is provided with an adjusting valve, the vacuum degree of the second kettle of the second wire polycondensation is directly adjusted through the opening degree of the adjusting valve, and the vacuum requirement of the second kettle of the second wire polycondensation can be completely met. When the original second-stage vacuum tube is blocked and needs to be washed, the second-stage auxiliary vacuum tube can be switched to, so that the original second-stage vacuum tube and the second-stage auxiliary vacuum tube can be mutually used as a standby, and the stability of the vacuum degree of the second-wire polycondensation kettle is kept. The EG circulating pipe of the second scraper condenser provides EG spraying liquid to the nozzle of the EG ring pipe, online annular spraying is achieved, particles in tail gas and condensable gas can be collected, the load of a vacuum unit is reduced, the blockage of a second-stage auxiliary vacuum pipe is avoided, a vacuum system is made to be more stable, and the spraying liquid of the EG ring pipe flows back to the second scraper condenser by means of the gradient of the second-stage auxiliary vacuum pipe. The vacuum degree of the two-wire final polycondensation kettle is generally 100-200 Pa (A), so that a top exhaust port of the third scraper condenser is connected with a first-stage steam jet pump with the largest suction force through a first-stage vacuum-pumping pipe, and the first-stage vacuum-pumping pipe is large in pipe diameter and not easy to block.

As a further improvement of the invention, the gas phase outlets of the two-wire pre-polycondensation kettle, the two-wire polycondensation kettle and the two-wire final polycondensation kettle are respectively connected with the side wall inlets of corresponding vacuum traps, the top gas phase outlet of each vacuum trap is respectively connected with the gas inlet of the corresponding scraper condenser, the bottom outlet of each vacuum trap is respectively connected with the top inlet of the corresponding vacuum collection tank through an electric cut-off valve, the top gas inlet of each vacuum collection tank is also connected with a nitrogen pipe through a nitrogen valve, and the bottom of each vacuum collection tank is provided with a collection tank discharge valve; the medium outlet of each scraper condenser is respectively connected with the corresponding hot well through an atmospheric leg, the EG outlet of each hot well is respectively connected with the inlet of a spraying circulating pump, the outlet of each spraying circulating pump is connected with the inlet of a cooler, and the outlet of each cooler is respectively connected with the spraying port of the corresponding scraper condenser through an EG circulating pipe. EG. After being discharged from a gas phase outlet of the polycondensation kettle, a mixture of water and oligomers firstly enters a vacuum catcher, because the gas velocity is reduced, the liquid oligomers are remained at the bottom of the vacuum catcher under the action of gravity, EG, water and a small amount of oligomers enter a scraper condenser to be sprayed and collected, the condensed oligomers are discharged from a medium outlet of the scraper condenser along with EG, enter a hot well through an atmosphere leg to be filtered, and the sprayed liquid EG is pumped out by a circulating pump and returns to a spraying port of the scraper condenser to be sprayed circularly after being cooled by a cooler. After accumulating to a certain level gauge in the vacuum trap, opening the electric cut-off valve, allowing nitrogen in the vacuum collection tank to enter the vacuum trap and be discharged from a gas phase outlet of the vacuum trap, allowing liquid oligomer to enter the vacuum collection tank for storage, opening a nitrogen valve of the vacuum collection tank after a certain amount of liquid oligomer is stored, allowing nitrogen to be charged into the vacuum collection tank, simultaneously opening a collection tank discharge valve at the bottom of the vacuum collection tank, discharging the liquid oligomer into the collection tank, continuously introducing nitrogen for about 10 seconds after the discharge is finished, performing nitrogen sealing on the vacuum collection tank, and then closing the nitrogen valve. Because most of the oligomer is collected by the vacuum catcher, the flow of the spraying liquid required by the scraper condenser is greatly reduced, the energy consumption is reduced, and the stability of a vacuum system is greatly improved; in addition, the amount of residue discharged into the hot well from the scraper condenser is greatly reduced, the running stability of the scraper is improved, and the service life of the scraper is greatly prolonged.

As a further improvement of the invention, the top of the hot well is provided with a hot well top cover, a longitudinal clapboard is arranged along the longitudinal axis of the hot well to divide the inner cavity of the hot well into a left half and a right half, a left inner chamber and a right inner chamber are symmetrically arranged at two sides of the middle section of the longitudinal clapboard, the outer side of the transverse wallboard of the left inner chamber is a left outer chamber, the outer side of the transverse wallboard of the right inner chamber is a right outer chamber, the bottoms of the left inner chamber and the right inner chamber are respectively provided with a conical hopper, the lowest part of the two conical hoppers is respectively connected with a hot well slag discharging port, and the two hot well slag discharging ports respectively extend downwards to the outside of the bottom of the hot well; the bottoms of the left outer chamber and the right outer chamber are respectively provided with a hot well EG outlet; the hot well top cover is spliced with two atmospheric legs, the lower ends of the two atmospheric legs are respectively inserted into the lower parts of the inner cavities of the left inner chamber and the right inner chamber, the upper part of each transverse wallboard is respectively provided with an overflow port communicated with the corresponding outer chamber, the inner port of each overflow port is respectively covered with a filter plate, the left side and the right side of each filter plate are respectively spliced in the vertical slots on the inner end surfaces of the transverse wallboards, the outer port of each overflow port is respectively covered with an outward-protruding arc-shaped filter basket, and the left side and the right side of each arc-shaped filter basket are respectively spliced in the vertical slots on the outer end surfaces of the transverse wallboards. EG and a little oligomer flow into the lower part of left inner room through left atmospheric leg through the valve and the pipeline of scraper condenser bottom earlier, play the liquid seal effect simultaneously, EG upwards flows out after the filter plate is filtered for the first time, gets into the inner chamber of arc filter basket, filters the basket secondary filter through the arc, gets into left outer room, flows out from the hot well EG export of left outer room bottom, is taken out by the circulating pump, after the cooling, send to scraper condenser circulation spray again. Impurities such as oligomer and the like are blocked in the left inner chamber, fall into the conical hopper, are discharged from a hot well slag discharge port and enter the cleaning box. If left atmosphere leg takes place to block up, then can switch to the work of the atmosphere leg on right side immediately, hot-well EG export and hot-well slag discharge mouth also switch to the work of right side, so can let spraying system long-term, operate steadily, guarantee polymerization facility's normal operating, avoid causing parking because of the atmosphere leg blocks up and handle, greatly reduce the loss, guarantee production normal operating. The filter plate is used for filtering for the first time and trapping impurities with larger sizes, and the filter plate is close to the top of the hot well, so that the filter plate is convenient to draw out and clean and is also convenient to install and return. The convex arc filter basket not only increases the filter area, but also increases the space for containing the objects; the filter plate and the edges of the left side and the right side of the arc-shaped filter basket are embedded in the vertical slots, so that the filter plate and the arc-shaped filter basket are convenient to pull, insert, clean and assemble.

As a further improvement of the invention, the two atmosphere legs are respectively positioned at two sides of the longitudinal partition plate and respectively penetrate through the central holes of the sealing seats, the two sealing seats are respectively welded on the top cover of the hot well, stuffing is respectively arranged in stuffing boxes between the outer walls of the atmosphere legs and the inner walls of the sealing seats, stuffing glands are respectively arranged at the upper parts of the stuffing, and flanges of the stuffing glands are connected with flanges of the sealing seats through gland screws. The gland screw is tightened, and the packing is tightly pressed in the packing box through the packing gland, so that the atmosphere leg is sealed at the periphery of the atmosphere leg, vertical free sliding of the atmosphere leg can be guaranteed, and the expansion caused by system temperature change can be automatically adapted.

As a further improvement of the invention, the hot well slag discharge port is respectively connected with a cleaning box feed inlet at the top of a cleaning box, the cleaning box comprises a horizontal barrel with one closed end, the front end port of the cleaning box is hinged with a cleaning box sealing cover which can be opened and closed, the periphery of the barrel of the cleaning box is coated with a cleaning box jacket, the inner cavity of the cleaning box is provided with a plurality of square filtering drawers which are sequentially superposed from top to bottom, the frames at the left side and the right side of each square filtering drawer are respectively supported in guiding chutes by rollers, each guiding chute extends along the axial direction of the cleaning box and is respectively fixed at the two sides of the inner wall of the cleaning box, the bottom of the inner cavity of the cleaning box is provided with an arc bottom drawer, the bottom of the arc bottom drawer is supported at the bottom of the inner wall of the cleaning box by rollers, the bottoms of the arc bottom drawer and each square filtering drawer are respectively provided with filtering nets, and the mesh number of the lower filtering net is sequentially larger than that of the upper filtering net, the lower end of the feed inlet of the cleaning box points to the central area of the square filter drawer at the top layer, and the bottom center of the cleaning box is provided with a liquid discharge port of the cleaning box. The frames of the drawers are erected upwards, so that the mixture can be prevented from overflowing from the periphery of the filter screen, the guide sliding grooves are convenient for the square filter drawers to be drawn out, cleaned and put back, and the square filter drawers can be ensured to be in a horizontal state; the drawer at the bottom of the arc is positioned at the bottom of the arc of the cleaning box and is in a stable and balanced state, so that the guide sliding groove can be omitted, and the drawer is directly supported at the bottom of the arc of the cleaning box through the idler wheels. The mixture of oligomer and EG enters the inner cavity of the cleaning box from the feeding hole of the cleaning box, firstly falls on the square filter drawer at the top layer, and is subjected to rough filtration, the mesh of the filter screen at the top layer is large, the liquid permeability is very strong, the overflow caused by blockage is avoided, the largest discharged slag is intercepted, and the slightly smaller discharged slag falls into the next layer for continuous filtration; so successive layer improves filter fineness, and the most tiny row of sediment is held back by arc bottom drawer, and after the multilayer filtered step by step, clear EG discharged from the cleaning box fluid-discharge outlet of cleaning bottom of the case portion. The square filtering drawer or the drawer with the arc-shaped bottom can be pulled out for cleaning by opening the cleaning box sealing cover, and the cleaning frequency can be higher than that of other square filtering drawers because the eyelet of the drawer with the arc-shaped bottom is smallest and is most easily blocked, so that each layer is not required to be pulled out for cleaning every time, the cleaning workload is reduced, and the pollution to the field working environment is reduced; the drawer with the arc-shaped bottom is deepest, and the height of the object to be stored is high, so that the overflow is not easy to cause. Steam can be introduced into the jacket of the cleaning box to improve the temperature of the inner cavity of the cleaning box and avoid blockage caused by medium solidification.

Drawings

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

FIG. 1 is a flow diagram of a flexible production system for polyester products of the present invention.

FIG. 2 is a detailed flow diagram of the two-line slurry dispensing tank of the present invention.

Fig. 3 is a cross-sectional view of the liquid dispenser of fig. 2.

FIG. 4 is a flow chart of the vacuum pumping system of the present invention.

Fig. 5 is a flow diagram of the squeegee spray system of the present invention.

Fig. 6 is a front view of the thermal well of fig. 5.

Figure 7 is a top view of figure 6 with the atmospheric leg removed.

Fig. 8 is a cross-sectional view taken along a-a in fig. 7.

Fig. 9 is a partially enlarged view of fig. 6.

FIG. 10 is a front view of the purge bin of FIG. 5.

Fig. 11 is a left side view of fig. 10.

In the figure: 1-1, a first line slurry preparation tank; 1-2, a second line slurry preparation tank; 1a powder inlet; 1b, spraying a column; 1c, liquid material distributor; 1c1, a distributor seal plate; 1c2. triangular tail gas outlet; 1c3. slit-shaped discharge ports; 1d. a cyclone separator; 1e, a draught fan; 2a, a first-line esterification kettle; 2b, two-line esterification in a kettle; 3a, a first-line esterification second kettle; 3b, a second line esterification second kettle; 4a, a first-line pre-polycondensation kettle; 4b, a second-line pre-polycondensation kettle; 5a, a first-line polycondensation two kettle; 5b, a second kettle for second-line polycondensation; 6a, a first-line final polycondensation kettle; 6b, a second-line final polycondensation kettle; 7. a scraper condenser; 7a, a first scraper condenser; 7b, a scraper condenser II; 7c, a third scraper condenser; 8. a hot well; 8a, a slag discharge port of the hot well; 8b, hot well EG outlet; 8c, a hot well level gauge port; 8d. thermal well temperature gauge mouth; 8e, hot well top cover; 8e1. hot well manhole covers; a longitudinal partition; 8g, transverse wall plates; 8h1. left inner chamber; 8h2. right inner chamber; 8j1. left outer compartment; 8j2. right outer chamber; 8k, a sealing seat; 8k1. filler; 8k2. packing gland; 8m, filtering plates; 8m1. strainer plate handle; 8n. arc-shaped filter basket; 8n1. basket handle; a conical hopper; an atmospheric leg; 9. a vacuum trap; 10. a vacuum collection tank; 11. cleaning the box; 11a, cleaning a box feed inlet; 11b, cleaning a box exhaust port; 11c, cleaning a liquid outlet of the tank; 11d, cleaning a box sealing cover; cleaning a box jacket; 11e1. cleaning box jacket lower interface; 11e2. jacket upper port; a square filter drawer; 11g, an arc-shaped bottom drawer; 11h, rolling wheels; 11j. a guide chute; searchlighting lamp sockets; 11m. glass sight glass viewing port; 11n. a multi-pipeline interface; 12a, a first process tower; 12b, a second process tower; a wire pelletizer; 13b, a two-wire pelletizer; a line spinning apparatus; a second thread spinning apparatus; g1.EG feed pipe; G2. a catalyst feed pipe; g3a.pta supply pipe; g3b.ipa feed tube; g4. auxiliary material supply tube; G5. a third-stage vacuum pumping pipe; g6a. a secondary vacuum tube; g6b, secondary auxiliary vacuum tubes; G7. a first-stage vacuum pumping pipe; g8.EG circulating pipe; g9.EG steam pipe; G10. a nitrogen gas pipe; g11a. heat medium supply pipe; g11b, a heating medium oil return pipe; b1a, a first slurry conveying pump; b1b, a slurry conveying pump II; b2a, a first ester material conveying pump; b2b, an ester material delivery pump II; EG reflux pump I; b3b.EG reflux pump II; b4a, a first melt delivery pump; b4b, a second melt delivery pump; B5. a spray circulation pump; C1. a cooler; p1, a primary steam jet pump; p2, a secondary steam jet pump; p3, a secondary semi-steam jet pump; p4, a three-stage steam jet pump; p5. liquid ring pump; J1. a primary spray tank; J2. a secondary spray tank; J3. a third stage spray tank; LT1. preparing a tank liquid level meter; lt2. trap level gauge; f1.EG flow meter; F2. a catalyst flow meter; v1.eg flow control valve; v2. catalyst flow control valve; v3. rotating the feed valve; v4. electric shut-off valve; v5. nitrogen gas valve; v6. collection tank drain valve; v7. flush the valve.

Detailed Description

As shown in figure 1, the flexible production system of polyester products comprises a first esterification polycondensation line and a second esterification polycondensation line, wherein the first esterification polycondensation line comprises a first line slurry preparation tank 1-1, a first line esterification first kettle 2a, a first line esterification second kettle 3a, a first line pre-polycondensation kettle 4a, a first line polycondensation second kettle 5a and a first line final polycondensation kettle 6a which are sequentially connected in series, a discharge port of the first line final polycondensation kettle 6a is connected with a first line granulator 13a or a first line spinning device 14a through a melt delivery pump B4a, the second esterification polycondensation line comprises a second line slurry preparation tank 1-2 which are sequentially connected in series, a discharge port of the second-line final polycondensation kettle 6B is connected with a second-line granulator 13B or a second-line spinning device 14B through a second melt delivery pump B4B; a PTA feed pipe G3a connected to the top of the first-line slurry preparation tank 1-1, an IPA feed pipe G3b connected to the top of the second-line slurry preparation tank 1-2; the first esterification kettle 2a is provided with a first esterification material delivery pump B2a at the bottom outlet, the second esterification kettle 2B is provided with a second esterification material delivery pump B2B at the bottom outlet, the first esterification material delivery pump B2a is connected with the feed inlet of the first esterification kettle 3a, the second esterification material delivery pump B2a is connected with the second esterification material delivery pump B2B at the outlet and the feed inlet of the second esterification kettle 3B at the two chambers respectively, the second esterification kettle 3B is of a horizontal multi-chamber structure and is provided with a stirrer and an auxiliary material injection port in each chamber, and each auxiliary material injection port is connected with an auxiliary material supply pipe G4.

EG. The PTA and the catalyst are uniformly stirred in a first-line slurry preparation tank 1-1, and can also be self-circulated through a first slurry conveying pump B1a, and after being uniformly mixed, the mixture is conveyed into a first-line esterification kettle 2a through a first slurry conveying pump B1a to carry out esterification reaction; EG. IPA and catalyst are stirred uniformly in the second-line slurry preparation tank 1-2, and self-circulation can be carried out through the second slurry delivery pump B1B, and the IPA and the catalyst are delivered into the first second-line esterification kettle 2B for esterification reaction after being uniformly mixed through the second slurry delivery pump B1B; the esterified substance of the first line esterification kettle 2a is sent out by an esterified material delivery pump B2a, the first line enters a first line esterification second kettle 3a for continuous reaction, and is sent to a first line granulator 13a for granulation or sent to a first line spinning device 14a for spinning by a melt delivery pump B4a after being polycondensed by a first line pre-polycondensation kettle 4a, a first line polycondensation second kettle 5a and a first line final polycondensation kettle 6a, and the traditional polyester products with luster and semi-dull degree can be produced.

The esterification product of the first second-line esterification kettle 2B is sent out by an esterification material delivery pump II B2B, mixed with the second path of material at the outlet of the first esterification material delivery pump II B2a, and then enters the second-line esterification kettle 3B, the related auxiliary materials of special varieties can be added into any chamber of the second-line esterification kettle 3B through an auxiliary material supply pipe G4, further esterification reaction is carried out under certain pressure, temperature and stirring conditions, after polycondensation is carried out by the second-line pre-polycondensation kettle 4B, the second-line polycondensation kettle 5B and the second-line final polycondensation kettle 6B, the second-line esterification kettle is sent to a second-line granulator 13B by a melt delivery pump II B4B for granulation or is sent to a second-line spinning device 14B for spinning, and special products such as cations, flame retardance, high shrinkage or bottle flakes can be produced. The production proportion of the two lines can be flexibly adjusted by only operating one line or operating one line and two lines simultaneously, and the production of conventional products is not influenced and the production change loss is avoided when special products are produced.

The outlet of the first esterification material delivery pump B2a is connected with the top circulation port of the first esterification kettle 2a through the first esterification circulation pipe, and the esterified materials with qualified esterification rate discharged from the first esterification kettle 2a return to the first esterification kettle 2a through the first esterification material delivery pump B2a and the esterification circulation pipe for circulation, so that the reaction rate in the first esterification kettle 2a is accelerated, the reaction time of the first esterification is shortened, and the materials are more uniform.

The outlet of the second esterified material delivery pump B2B is connected with the top circulation port of the first second-line esterification kettle 2B through a second esterified circulation pipe, and esterified materials with qualified esterification rate discharged from the first second-line esterification kettle 2B return to the first second-line esterification kettle 2B for circulation through the second esterified material delivery pump B2B and the second esterified circulation pipe, so that the reaction rate in the first second-line esterification kettle 2B is accelerated, the reaction time of the second-line esterification is shortened, and the materials are more uniform.

The air outlets of the first line esterification kettle 2a, the first line esterification kettle 3a and the second line esterification kettle 2B are connected with the air inlet of the first process tower 12a, the bottom of the first process tower 12a is provided with a first EG reflux pump B3a, and the outlet of the first EG reflux pump B3a is connected with the top reflux ports of the first line esterification kettle 2a, the first line esterification kettle 3a and the second line esterification kettle 2B through EG reflux pipes. EG and water vapor discharged from exhaust ports of the first line esterification first kettle 2a, the first line esterification second kettle 3a and the second line esterification first kettle 2B enter the first process tower 12a for rectification, and EG at the bottom of the first process tower 12a flows back to the first line esterification first kettle 2a, the first line esterification second kettle 3a and the second line esterification first kettle 2B through an EG reflux pump B3a.

The air outlet of the second two-line esterification kettle 3B is connected with the air inlet of a second process tower 12B, the bottom of the second process tower 12B is provided with a second EG reflux pump B3B, and the outlet of the second EG reflux pump B3B is connected with the top reflux port of the second two-line esterification kettle 3B through an EG reflux pipe. The second-line esterification second kettle 3b is independently matched with the second process tower 12b due to the addition of special materials, and the EG and the water vapor discharged from the second-line esterification second kettle 3b are rectified.

As shown in fig. 2 and 3, a powder inlet 1a at the top of the second-line slurry preparation tank 1-2 is connected with an IPA feed pipe G3b, a spray column 1b extending vertically is further installed at the top of the second-line slurry preparation tank 1-2, a preparation tank exhaust pipe is connected to the top of the spray column 1b, an outlet of the preparation tank exhaust pipe is connected with an air inlet of a cyclone separator 1d, an air outlet at the top of the cyclone separator 1d is connected with an induced draft fan 1e, and a bottom outlet of the cyclone separator 1d is connected with a return port at the top of the second-line slurry preparation tank 1-2 through a separator return valve and a powder return pipe; an EG nozzle and a catalyst nozzle are sequentially arranged in the inner cavity of the spraying column 1b from top to bottom, the EG nozzle is connected with an EG feeding pipe G1, and the catalyst nozzle is connected with a catalyst feeding pipe G2; the lower end of the spraying column 1b is inserted into an inner cavity of the second-line slurry preparation tank 1-2 and is connected with a liquid distributor 1c, the top of the middle section of the liquid distributor 1c is communicated with the lower port of the spraying column 1b and symmetrically extends along the radial direction of the second-line slurry preparation tank 1-2 by taking the axis of the spraying column as the center, the vertical section of the liquid distributor 1c is in a diamond shape, distributor seal plates 1c1 are respectively arranged at the middle lower parts of the two ends of the liquid distributor 1c, triangular tail gas outlets 1c2 are respectively arranged above the two distributor seal plates 1c1, and the lower end of the liquid distributor 1c is provided with a strip slit-shaped discharge port 1c3 which is as long as the liquid distributor 1c.

The low-temperature EG enters the spraying column 1b from an EG feed pipe G1 and is sprayed downwards from an EG spray head; the high-temperature catalyst enters the spray column 1b from the catalyst feed pipe G2 and is sprayed downwards from the catalyst spray head; because the temperature of the catalyst is high, the flow rate is small, the temperature of EG is low, and the flow rate is large, the catalyst spray head is closer to the second-line slurry preparation tank 1-2, the EG spray head is arranged above the catalyst spray head, EG is mixed with the catalyst solution in the downward spraying process and falls into the middle section of the liquid material distributor 1c together, liquid is distributed downwards along the strip-shaped discharge port 1c3 in the flowing process towards the two ends of the liquid material distributor, and the liquid level height in the liquid material distributor 1c is lower than the height of the distributor seal plate 1c 1; IPA powder falls into the second-line slurry preparation tank 1-2 from an IPA feeding pipe G3B and a powder inlet 1a, the IPA powder and EG and catalyst which are uniformly distributed along the radius are easier to mix under the action of a preparation tank stirrer, the uniformly mixed slurry enters a second slurry delivery pump B1B from the bottom of the second-line slurry preparation tank 1-2, and the second slurry delivery pump B1B delivers the prepared slurry into a first second-line esterification kettle 2B through a slurry output pipe for esterification. Under the suction action of a draught fan 1e, the second-line slurry preparation tank 1-2 is kept in a micro-negative pressure state, so that IPA powder can be conveniently discharged, the phenomenon that the powder overflows outwards due to positive pressure is avoided, tail gas enters the upper part of an inner cavity of the liquid material distributor 1c from two triangular tail gas outlets 1c2 and upwards enters the spraying column 1b, floating IPA powder is sprayed by a catalyst spray head and an EG spray head in two stages in the ascending process, most IPA powder is trapped and falls back to the second-line slurry preparation tank 1-2, the dust content in the tail gas is reduced, a small amount of IPA powder enters the cyclone separator 1d for separation, the IPA powder deposited at the bottom of the cyclone separator 1d is accumulated to a certain amount, a separator return valve is opened and the IPA powder returns to the second-line slurry preparation tank 1-2 through a powder return pipe, the IPA powder can be completely recycled, the loss of raw materials is reduced, but also improves the field operation environment and avoids environmental pollution.

The long diagonal line of the liquid distributor 1c extends along a vertical plane where the axis of the spraying column is located, and the included angle of two surfaces at the top of the liquid distributor 1c is 30 degrees; so that the powder falling on the top surface of the liquid distributor 1c can easily slide off and can be prevented from accumulating on the top surface of the liquid distributor 1c.

The larger the distance from the axis of the spray column, the wider the slit of the slit-shaped outlet 1c3. The seam just below the spraying column 1b is easier to discharge, and the seam with longer flowing distance is wider, which is beneficial to uniform radial discharge of the slurry preparation tank.

As shown in fig. 2, a preparation tank level meter LT1 is installed at the bottom of the second-line slurry preparation tank 1-2, a rotary feed valve V3 is installed on the IPA feed pipe G3b, an EG flow meter F1 and an EG flow control valve V1 are installed on the EG feed pipe G1, a catalyst flow meter F2 and a catalyst flow control valve V2 are installed on the catalyst feed pipe G2, the opening degrees of the EG flow control valve V1 and the catalyst flow control valve V2 are controlled by the flow rate of the rotary feed valve V3, and the flow rate of the rotary feed valve V3 is controlled by the second-line slurry preparation tank level measured by the preparation tank level meter LT1. When the flow rate of IPA is increased, the opening degrees of the EG flow control valve V1 and the catalyst flow control valve V2 are increased in equal proportion, and thus the exact molar ratio of EG, catalyst, and IPA can be maintained, and the quality of slurry preparation can be improved.

The first-line slurry preparation tank 1-1 can adopt a traditional structure and can also adopt the same structure and flow as the second-line slurry preparation tank 1-2, and a powder inlet at the top of the first-line slurry preparation tank 1-1 is connected with a PTA feeding pipe G3a.

As shown in FIG. 4, the gas phase outlet of the two-wire prepolycondensation reactor 4b is connected with the gas inlet of the first scraper condenser 7a, the gas phase outlet of the two-wire prepolycondensation reactor 5b is connected with the gas inlet of the second scraper condenser 7b, the gas phase outlet of the two-wire final polycondensation reactor 6b is connected with the gas inlet of the third scraper condenser 7c, the top exhaust port of the third scraper condenser 7c is connected with the suction port of the first-stage steam jet pump P1 through a first-stage vacuum tube G7, the top exhaust port of the second scraper condenser 7b is connected with the suction port of the second-stage half steam jet pump P3 through a second-stage vacuum tube G6a, the top exhaust port of the first scraper condenser 7a is connected with the suction port of the liquid ring pump P5 through a third-stage vacuum tube G5 and a vacuum regulating valve, the outlet of the first-stage steam jet pump P1 is connected with the gas inlet of the first-stage spray tank J1, the exhaust port of the first-stage spray tank J1 is connected with the suction port of the second-stage steam jet pump P2, outlets of a second-stage steam jet pump P2 and a second-stage semi-steam jet pump P3 are connected with an air inlet of a second-stage spray tank J2, an air outlet of the second-stage spray tank J2 is connected with a suction port of a third-stage steam jet pump P4, an outlet of the third-stage steam jet pump P4 is connected with an air inlet of a third-stage spray tank J3, and an air outlet of the third-stage spray tank J3 is connected with a suction port of a liquid ring pump P5; the top exhaust port of the second scraper condenser 7b is also connected with a first-level spray tank J1 through a second-level auxiliary vacuum tube G6b, EG circular tubes are arranged on the inner wall of the second-level auxiliary vacuum tube G6b at certain intervals, nozzles are uniformly distributed on the circumference of the EG circular tubes, and each EG circular tube is connected with an EG circular tube G8 of the second scraper condenser 7b.

The vacuum requirement of the second-line prepolycondensation kettle 4b is not high, generally 8-15 KPa (A), the vacuum of the inlet of a liquid ring pump P5 behind a vacuum jet unit can be controlled at 5-20 KPa, and the vacuum requirement of the second-line prepolycondensation kettle 4b can be met, so that the exhaust port of the first scraper condenser 7a is directly connected with the liquid ring pump P5 behind the vacuum jet unit through an adjusting valve, the original independent liquid ring pump of the second-line prepolycondensation kettle 4b is cancelled, and the equipment investment cost and the occupation of the workshop area are reduced. The vacuum of the second-line polycondensation kettle 5b is generally 0.8-1.5 KPa (A), the vacuum of the first-stage spraying tank J1 is below 0.8KPa (A), a second-stage auxiliary vacuum tube G6b is added at an exhaust port of the second scraper condenser 7b and is connected with the first-stage spraying tank J1, an adjusting valve is installed on the second-stage auxiliary vacuum tube G6b, the vacuum degree of the second-line polycondensation kettle 5b is directly adjusted through the opening degree of the adjusting valve, and the vacuum requirement of the second-line polycondensation kettle 5b can be completely met. When the original second-stage vacuumizing tube G6a is blocked and needs to be flushed, the second-stage auxiliary vacuum tube G6b can be switched to, so that the original second-stage vacuumizing tube G6a and the second-stage auxiliary vacuum tube G6b can be mutually used for standby, and the stability of the vacuum degree of the second polycondensation kettle 5b is kept. The EG circulating pipe G8 of the second scraper condenser 7b is used for providing EG spraying liquid for the nozzle of the EG ring pipe, online annular spraying is achieved, particles and condensable gas in tail gas can be further collected, the load of a vacuum unit is reduced, the blockage of a second-stage auxiliary vacuum pipe G6b is avoided, a vacuum system is enabled to be more stable, and the spraying liquid of the EG ring pipe flows back to the second scraper condenser 7b by means of the gradient of the second-stage auxiliary vacuum pipe G6b. The vacuum degree of the two-wire final polycondensation kettle 6b is generally 100-200 Pa (A), so that a top exhaust port of the third scraper condenser 7c is connected with a first-stage steam jet pump P1 with the largest suction force through a first-stage vacuum-pumping pipe G7, and the first-stage vacuum-pumping pipe G7 is large in pipe diameter and not easy to block.

The tail end of the secondary vacuum tube G6a is connected with an EG steam tube G9 through a flushing valve V7, and the flushing valve V7 is opened periodically, so that EG steam can be used for cleaning the secondary vacuum tube G6a and the secondary semi-steam jet pump P3, and blockage is eliminated.

As shown in fig. 5, the gas phase outlets of the second-wire prepolycondensation reactor 4b, the second-wire polycondensation reactor 5b and the second-wire final polycondensation reactor 6b are respectively connected to the side wall inlets of the corresponding vacuum traps 9, the top gas phase outlet of each vacuum trap 9 is respectively connected to the gas inlet of the corresponding scraper condenser 7, the bottom outlet of each vacuum trap 9 is respectively connected to the top inlet of the corresponding vacuum collection tank 10 through an electric cut-off valve V4, the top gas inlet of each vacuum collection tank 10 is further connected to a nitrogen pipe G10 through a nitrogen valve V5, and the bottom of each vacuum collection tank 10 is provided with a collection tank discharge valve V6; the medium outlet of each scraper condenser 7 is respectively connected with the corresponding hot well 8 through an atmosphere leg, the EG outlet of each hot well 8 is respectively connected with the inlet of a spray circulating pump B5, the outlet of each spray circulating pump B5 is connected with the inlet of a cooler C1, and the outlet of each cooler C1 is respectively connected with the spray opening of the corresponding scraper condenser 7 through an EG circulating pipe G8.

EG. After being discharged from a gas phase outlet of the polycondensation kettle, a mixture of water and oligomers firstly enters a vacuum catcher 9, liquid oligomers are remained at the bottom of the vacuum catcher 9 under the action of gravity due to the reduction of gas velocity, EG, water and a small amount of oligomers enter a scraper condenser 7 to be sprayed and collected, the condensed oligomers are discharged from a medium outlet of the scraper condenser 7 along with EG, enter a hot well 8 through an atmospheric leg to be filtered, and the sprayed liquid EG is pumped out by a circulating pump, cooled by a cooler C1 and then returns to a spraying port of the scraper condenser 7 to be sprayed circularly. When a certain liquid level meter is accumulated in the vacuum catcher 9, the electric cut-off valve V4 is opened, nitrogen in the vacuum collection tank 10 enters the vacuum catcher 9 and is discharged from a gas phase outlet of the vacuum catcher 9, liquid oligomer enters the vacuum collection tank 10 for storage, after a certain amount of storage, the nitrogen valve V5 of the vacuum collection tank 10 is opened, the nitrogen is filled into the vacuum collection tank 10, the collection tank discharge valve V6 at the bottom of the vacuum collection tank 10 is opened, the liquid oligomer is discharged into the collection tank, after the discharge is finished, the nitrogen is continuously introduced for about 10 seconds, the vacuum collection tank 10 is subjected to nitrogen sealing, and then the nitrogen valve V5 is closed. Because most of the oligomer is collected by the vacuum catcher 9, the flow of the spraying liquid required by the scraper condenser is greatly reduced, the energy consumption is reduced, and the stability of a vacuum system is greatly improved; in addition, the amount of residue discharged into the hot well 8 from the scraper condenser is greatly reduced, the stability of scraper operation is improved, and the service life of the scraper is greatly prolonged.

The outer walls of the vacuum catcher 9 and the vacuum collecting tank 10 are respectively coiled with a half-pipe heater, the lower end inlets of the two half-pipe heaters are respectively connected with a heating medium oil supply pipe G11a, and the upper end outlets of the two half-pipe heaters are respectively connected with a heating medium oil return pipe G11b. By heating the heating medium, the vacuum catcher 9 and the vacuum collecting tank 10 can be kept above the melting point of various media, so that the various media can be kept in fluidity, and solidification blockage is avoided.

A catcher liquid level meter LT2 is installed in the middle section of the side wall of the vacuum catcher 9, the opening and closing of the electric cut-off valve V4 is controlled by the catcher liquid level meter LT2, and the vacuum collection tank 10 is provided with a pressure sensor. When the liquid level in the vacuum trap 9 reaches the level of the trap level gauge LT2, the electric shut-off valve V4 opens the drain. The pressure of the vacuum collection tank 10 can be observed by the pressure sensor, and the completion of the nitrogen seal and the formation of the negative pressure can be judged.

The first esterification polycondensation line can adopt a traditional vacuum-pumping system, and can also adopt the same vacuum-pumping system as the second esterification polycondensation line.

As shown in fig. 6, 7, 8 and 9, a hot well top cover 8e is arranged at the top of the hot well 8, a longitudinal partition plate 8f is arranged along the longitudinal axis of the hot well 8 to divide the inner cavity of the hot well into a left half and a right half, a left inner chamber 8h1 and a right inner chamber 8h2 are symmetrically arranged at two sides of the middle section of the longitudinal partition plate 8f, transverse wall plates 8g are respectively arranged at the front and the rear of the left inner chamber 8h1 and the right inner chamber 8h2, the outer space of the left inner chamber 8h1 is a left outer chamber 8j1, the outer space of the right inner chamber 8h2 is a right outer chamber 8j2, tapered hoppers 8p are respectively arranged at the bottoms of the left inner chamber 8h1 and the right inner chamber 8h2, the lowest positions of the two tapered hoppers 8p are respectively connected with hot well slag discharge ports 8a, and the two hot well slag discharge ports 8a respectively extend downwards to the bottom of the hot well 8 and are respectively connected with the cleaning box 11.

The bottoms of the left outer chamber 8j1 and the right outer chamber 8j2 are respectively provided with a hot well EG outlet 8 b; two atmospheric legs 8q are inserted on the hot well top cover 8e, the lower ends of the two atmospheric legs 8q are respectively inserted into the lower parts of the inner cavities of the left inner chamber 8h1 and the right inner chamber 8h2, the upper parts of the transverse wall plates 8g are respectively provided with an overflow port communicated with the corresponding outer chamber, the inner ports of the overflow ports are respectively covered with a filter plate 8m, the left side and the right side of each filter plate 8m are respectively inserted into the vertical slots on the inner end surfaces of the transverse wall plates 8g, the outer ports of the overflow ports are respectively covered with an arc filter basket 8n which protrudes outwards, and the left side and the right side of each arc filter basket 8n are respectively inserted into the vertical slots on the outer end surfaces of the transverse wall plates 8g.

EG and a little oligomer flow into the lower part of the left inner chamber 8h1 through a valve and a pipeline at the bottom of the scraper condenser through the left atmospheric leg 8q, and simultaneously play a role of liquid seal, EG flows out after being filtered for the first time by a filter plate 8m upwards, enters the inner cavity of an arc filter basket 8n, enters a left outer chamber 8j1 after being filtered for the second time by the arc filter basket 8n, flows out from a hot well EG outlet 8B at the bottom of the left outer chamber 8j1, is pumped out by a circulating pump B5, is cooled, and then is sent to the scraper condenser for circulating spraying. Impurities such as oligomers are retained in the left interior chamber 8h1, fall into the conical hopper 8p, and are discharged from the hot well slag discharge port 8a into the purge bin 11. If left atmospheric leg 8q takes place to block up, then can switch to the work of the atmospheric leg 8q on right side immediately, hot-well EG export 8b and hot-well slag tap 8a also switch to the work of right side, so can let spraying system long-term, operate steadily, guarantee polymerization facility's normal operating, avoid causing parking because of atmospheric leg 8q blocks up and handle, greatly reduce the loss, guarantee production normal operating.

The filter plate 8m is used for filtering for the first time and intercepting large-size impurities, and the filter plate 8m is close to the top of the vacuum sealing tank, so that the filter plate 8m is convenient to draw out and clean and is also convenient to put back. The convex arc-shaped filter basket 8n not only increases the filtering area, but also increases the containing space; the filter plate 8m and the edges of the left side and the right side of the arc-shaped filter basket 8n are embedded in the vertical slots, so that the filter plate is convenient to pull, insert, clean and assemble.

Each arc-shaped filter basket 8n extends towards the lower part of the corresponding outer chamber, and the cambered surface and the bottom of each arc-shaped filter basket 8n are respectively provided with a filter screen. The filtering area of the arc-shaped filtering basket 8n is further increased, so that the arc-shaped filtering basket 8n only needs to be cleaned once after the system continuously works for several days, and the cleaning workload is reduced.

Two hot well manhole covers 8e1 are symmetrically arranged on the position, far away from the longitudinal partition plate 8f, on the transverse axis of the hot well top cover 8e, and each pair of filter plates 8m and the arc-shaped filter baskets 8n are respectively positioned below the hole openings of the hot well manhole covers 8e1. The hot well manhole cover 8e1 is opened, the filter plate 8m and the arc filter basket 8n can be pulled out for cleaning, the filter plate 8m and the arc filter basket 8n are inserted back after cleaning, and then the hot well manhole cover 8e1 is reset, so that the hot well top cover 8e is prevented from being integrally detached, and the workload during cleaning is reduced.

Handles are respectively arranged at the tops of the filter plates 8m and the arc-shaped filter baskets 8n. The filter plate 8m can be easily inserted and pulled out by the filter plate handle 8m1, and the arc-shaped filter basket 8n can be easily inserted and pulled out by the filter basket handle 8n1.

The left inner chamber 8h1, the right inner chamber 8h2, the left outer chamber 8j1 and the right outer chamber 8j2 are respectively provided with a hot well material level meter port 8c, the material levels of the inner chamber and the outer chamber can be displayed and monitored on the DCS in real time, and when the atmosphere leg 8q is blocked, the DCS sends alarm information in real time, so that DCS personnel can rapidly arrange field personnel for processing.

Thermal well temperature ports 8d are respectively arranged at the bottom of two sides of the thermal well 8, and the temperature of EG can be displayed on DCS in real time.

The two atmospheric legs 8q are respectively positioned at two sides of the longitudinal partition plate 8f and respectively penetrate through central holes of the sealing seats 8k, the two sealing seats 8k are respectively welded on a hot well top cover 8e, packing 8k1 is respectively arranged in a packing box between the outer wall of the atmospheric leg 8q and the inner wall of the sealing seat, a packing gland 8k2 is respectively arranged at the upper part of the packing 8k1, and a flange of the packing gland 8k2 is connected with a flange of the sealing seat 8k through gland screws. The gland screw is tightened, the packing 8k1 is tightly pressed in the stuffing box through the packing gland 8k2, the periphery of the atmospheric leg 8q is sealed, the atmospheric leg 8q can be guaranteed to vertically and freely slide, and the expansion caused by the temperature change of the system can be automatically adapted.

As shown in fig. 10 and 11, the cleaning box 11 includes a horizontal cylinder with a closed end, a cleaning box cover 11d is hinged to the front end of the cleaning box 11, the cleaning box cover 11e is wrapped around the cylinder of the cleaning box 11, a plurality of square filter drawers 11f are sequentially stacked in the inner cavity of the cleaning box 11 from top to bottom, the frames on the left and right sides of each square filter drawer 11f are respectively supported in the guide chutes 11j through rollers 11h, the guide chutes 11j extend along the axial direction of the cleaning box 11 and are respectively fixed on the two sides of the inner wall of the cleaning box 11, an arc bottom drawer 11g is arranged at the bottom of the inner cavity of the cleaning box 11, the bottom of the arc bottom drawer 11g is supported at the bottom of the inner wall of the cleaning box 11 through rollers 11h, the bottoms of the arc bottom drawer 11g and the square filter drawers 11f are respectively provided with filter screens, and the mesh number of the lower filter screen is sequentially larger than that of the upper filter screen, the top of the cleaning box 11 is provided with a cleaning box feed inlet 11a and a cleaning box exhaust port 11b, the upper end of the cleaning box feed inlet 11a is connected with a hot well slag discharge port 23a, the lower end of the cleaning box feed inlet 11a points to the central area of the top square filtering drawer 11f, and the bottom center of the cleaning box 11 is provided with a cleaning box liquid discharge port 11c.

The frames of the drawers are erected upwards, so that the mixture can be prevented from overflowing from the periphery of the filter screen, the guide sliding grooves 11j are convenient for the square filter drawers 11f to be drawn out, cleaned and put back, and the square filter drawers 11f can be ensured to be in a horizontal state; the drawer 11g with the arc bottom is positioned at the arc bottom of the cleaning box 11 and is in a stable and balanced state, a guide chute 11j can be omitted, and the drawer with the arc bottom is directly supported at the arc bottom of the cleaning box 11 through the idler wheels 11h. The mixture of oligomer and EG enters the inner cavity of the cleaning box 11 from the feeding hole 11a of the cleaning box, firstly falls on the square filtering drawer 11f at the top layer, and is subjected to rough filtering, the mesh of the filter screen at the top layer is large, the liquid permeability is strong, the overflow caused by blockage is avoided, the maximum slag discharge is intercepted, and the slightly smaller slag discharge completely falls into the next layer for continuous filtering; so the successive layer improves filtration precision, and the finest row of sediment is held back by arc bottom drawer 11g, filters the back step by step through the multilayer, and clear EG is discharged from cleaning box leakage fluid dram 11c of cleaning box 11 bottom. The square filtering drawer 11f or the arc-shaped bottom drawer 11g can be pulled out for cleaning by opening the cleaning box sealing cover 11d, and the cleaning frequency can be higher than that of other square filtering drawers 11f because the holes of the arc-shaped bottom drawer 11g are smallest and are most easily blocked, so that each layer is not required to be pulled out for cleaning every time, the cleaning workload is reduced, and the pollution to the field working environment is reduced; the drawer 11g with the arc-shaped bottom is deepest, and the height of the contained objects is high, so that overflow is not easy to cause.

A searchlight socket 11k and a glass sight glass observation port 11m are respectively arranged on the left side and the right side of the exhaust port 11b of the cleaning box, light is injected from the searchlight socket 11k, and the inner interception state can be observed from the glass sight glass observation port 11m on the other side, so that the cleaning time can be accurately determined.

The bottom of the cleaning box jacket 11e is connected with a cleaning box jacket lower connector 11e1, the top of the cleaning box jacket 11e is connected with a jacket upper connector 11e2, steam can be introduced into the cleaning box jacket 11e, the steam enters from the jacket upper connector 11e2 at the top, and condensed water is discharged from the cleaning box jacket lower connector 11e1 at the bottom, so that the temperature of the inner cavity of the cleaning box 11 is increased, and blockage caused by medium solidification is avoided.

The top of the cleaning box 11 is also provided with a multi-pipeline interface 11n, and the multi-pipeline interface 11n can be used for pressure measurement, liquid supplement or inert gas protection and the like.

Claims

1. The utility model provides a flexible production system of polyester product, is including esterification polycondensation one line, esterification polycondensation one line is including a line of thick liquids preparation jar, a line of one line of esterification cauldron, a line of two cauldron of esterification, a line of pre-polycondensation cauldron, a line of two cauldron of polycondensation and a line of final polycondensation cauldron that establish ties in proper order, and the discharge gate of a line of final polycondensation cauldron passes through a melt-conveying pump one and a line of pelleter or a line of spinning equipment and links to each other its characterized in that: the device also comprises an esterification polycondensation second line, wherein the esterification polycondensation second line comprises a second-line slurry preparation tank, a second-line esterification first kettle, a second-line esterification second kettle, a second-line pre-polycondensation kettle, a second-line polycondensation second kettle and a second-line final polycondensation kettle which are sequentially connected in series, and a discharge port of the second-line final polycondensation kettle is connected with a second-line granulator or second-line spinning equipment through a second melt delivery pump; the PTA feeding pipe is connected with the top of the first-line slurry preparation tank, and the IPA feeding pipe is connected with the top of the second-line slurry preparation tank; the first esterification material delivery pump is installed at the bottom outlet of the first esterification kettle, the second esterification material delivery pump is installed at the bottom outlet of the first esterification kettle, the first outlet branch of the first esterification material delivery pump is connected with the feed inlet of the first esterification kettle, the second outlet branch of the first esterification material delivery pump is connected with the feed inlet of the second esterification kettle together with the outlet of the second esterification material delivery pump, the second esterification kettle is of a horizontal multi-chamber structure, and each chamber is provided with an agitator and an auxiliary material injection port respectively, and each auxiliary material injection port is connected with an auxiliary material supply pipe respectively.

2. The flexible production system of polyester products according to claim 1, characterized in that: the outlet of the first esterification material conveying pump is also connected with the top circulation port of the first linear esterification kettle through a first esterification circulation pipe; and the outlet of the second esterification material conveying pump is also connected with the top circulating port of the second-line first esterification kettle through a second esterification circulating pipe.

3. The flexible production system of polyester products according to claim 1, characterized in that: the air outlets of the first line esterification kettle, the first line esterification kettle and the second line esterification kettle are connected with an air inlet of a first process tower, the bottom of the first process tower is provided with a first EG reflux pump, and the outlet of the first EG reflux pump is connected with the top reflux ports of the first line esterification kettle, the first line esterification kettle and the second line esterification kettle through EG reflux pipes; and the gas outlet of the second two-line esterification kettle is connected with the gas inlet of the second process tower, the bottom of the second process tower is provided with a second EG reflux pump, and the outlet of the second EG reflux pump is connected with the top reflux port of the second two-line esterification kettle through an EG reflux pipe.

4. The flexible production system of polyester products according to claim 1, characterized in that: a powder inlet at the top of the second-line slurry preparation tank is connected with an IPA feeding pipe, a spraying column extending vertically is further installed at the top of the second-line slurry preparation tank, a preparation tank exhaust pipe is connected to the top of the spraying column, 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 return port at the top of the second-line slurry preparation tank through a separator return valve and a powder return pipe; an EG spray head and a catalyst spray head are sequentially arranged in an inner cavity of the spray column from top to bottom, the EG spray head is connected with an EG feed pipe, and the catalyst spray head is connected with a catalyst feed pipe; the lower extreme that sprays the post inserts second line thick liquids and prepares jar inner chamber and is connected with the liquid material distributor, the middle section top of liquid material distributor and the lower port that sprays the post link up mutually and use and spray the post axis and follow the radial symmetry extension of second line thick liquids preparation jar as the center, the vertical cross-section of liquid material distributor is the rhombus, and the well lower part at liquid material distributor both ends is equipped with the distributor shrouding respectively, and the top of bipartition distributor shrouding is equipped with triangle-shaped tail gas respectively and exports, the lower extreme of liquid material distributor is equipped with the strip seam shape discharge gate isometric with the liquid material distributor.

5. The flexible production system of polyester products according to claim 4, characterized in that: the long diagonal line of the liquid distributor extends along a vertical plane where the axis of the spraying column is located, and the included angle of two surfaces at the top of the liquid distributor is 30 degrees; the larger the distance from the axis of the spraying column is, the wider the slit opening of the strip slit-shaped discharge port is.

6. The flexible production system of polyester products according to claim 4, characterized in that: the bottom of jar is joined in marriage to second-line thick liquids is installed and is joined in marriage the preparation jar level gauge, be equipped with rotatory feed valve on the IPA feed pipe, install EG flowmeter and EG flow control valve on the EG feed pipe, install catalyst flowmeter and catalyst flow control valve on the catalyst feed pipe, the aperture of EG flow control valve and catalyst flow control valve all is controlled by rotatory feed valve's flow, rotatory feed valve's flow is controlled by the jar liquid level is joined in marriage to second-line thick liquids that preparation jar level gauge surveyed.

7. The flexible production system of polyester products according to any of claims 1 to 6, characterized in that: the gas phase outlet of the two-wire pre-polycondensation kettle is connected with the gas inlet of the first scraper condenser, the gas phase outlet of the two-wire pre-polycondensation kettle is connected with the gas inlet of the second scraper condenser, the gas phase outlet of the two-wire final polycondensation kettle is connected with the gas inlet of the third scraper condenser, the top exhaust port of the third scraper condenser is connected with the suction port of the first-stage steam jet pump through the first-stage vacuum tube, the top exhaust port of the second scraper condenser is connected with the suction port of the second-stage semi-steam jet pump through the second-stage vacuum tube, the top exhaust port of the first scraper condenser is connected with the suction port of the liquid ring pump through the third-stage vacuum tube and the vacuum regulating valve, the outlet of the first-stage steam jet pump is connected with the gas inlet of the first-stage spray tank, the exhaust port of the first-stage spray tank is connected with the suction port of the second-stage steam jet pump, and the outlet of the second-stage semi-steam jet pump are both connected with the gas inlet of the second-stage spray tank, an exhaust port of the second-stage spraying tank is connected with a suction port of the third-stage steam jet pump, an outlet of the third-stage steam jet pump is connected with an air inlet of the third-stage spraying tank, and an exhaust port of the third-stage spraying tank is connected with a suction port of the liquid ring pump; and the top exhaust port of the second scraper condenser is also connected with the first-stage spray tank through a second-stage auxiliary vacuum tube, EG circular tubes are arranged on the inner wall of the second-stage auxiliary vacuum tube at intervals of a certain distance, nozzles are uniformly distributed on the circumference of the EG circular tubes, and each EG circular tube is connected with an EG circulating tube of the second scraper condenser.

8. The flexible production system of polyester products according to claim 7, characterized in that: the gas phase outlets of the two-wire pre-polycondensation kettle, the two-wire polycondensation kettle and the two-wire final polycondensation kettle are respectively connected with the side wall inlets of corresponding vacuum catchers, the top gas phase outlet of each vacuum catcher is respectively connected with the gas inlet of the corresponding scraper condenser, the bottom outlet of each vacuum catcher is respectively connected with the top inlet of the corresponding vacuum collection tank through an electric cut-off valve, the top gas inlet of each vacuum collection tank is also connected with a nitrogen pipe through a nitrogen valve, and the bottom of each vacuum collection tank is provided with a collection tank discharge valve; the medium outlet of each scraper condenser is respectively connected with the corresponding hot well through an atmospheric leg, the EG outlet of each hot well is respectively connected with the inlet of a spraying circulating pump, the outlet of each spraying circulating pump is connected with the inlet of a cooler, and the outlet of each cooler is respectively connected with the spraying port of the corresponding scraper condenser through an EG circulating pipe.

9. The flexible production system of polyester products according to claim 8, characterized in that: the top of the hot well is provided with a hot well top cover, a longitudinal clapboard is arranged along the longitudinal axis of the hot well to divide the inner cavity of the hot well into a left half and a right half, a left inner chamber and a right inner chamber are symmetrically arranged at two sides of the middle section of the longitudinal clapboard, the outer side of the transverse wallboard of the left inner chamber is a left outer chamber, the outer side of the transverse wallboard of the right inner chamber is a right outer chamber, the bottoms of the left inner chamber and the right inner chamber are respectively provided with a conical hopper, the lowest part of the two conical hoppers is respectively connected with a hot well slag discharge port, and the two hot well slag discharge ports respectively extend downwards to the outside of the bottom of the hot well; the bottoms of the left outer chamber and the right outer chamber are respectively provided with a hot well EG outlet; the hot well top cover is spliced with two atmospheric legs, the lower ends of the two atmospheric legs are respectively inserted into the lower parts of the inner cavities of the left inner chamber and the right inner chamber, the upper part of each transverse wallboard is respectively provided with an overflow port communicated with the corresponding outer chamber, the inner port of each overflow port is respectively covered with a filter plate, the left side and the right side of each filter plate are respectively spliced in the vertical slots on the inner end surfaces of the transverse wallboards, the outer port of each overflow port is respectively covered with an outward-protruding arc-shaped filter basket, and the left side and the right side of each arc-shaped filter basket are respectively spliced in the vertical slots on the outer end surfaces of the transverse wallboards.

10. The flexible production system of polyester products according to claim 9, characterized in that: the two atmosphere legs are respectively positioned on two sides of the longitudinal partition plate and respectively penetrate through the central holes of the sealing seats, the two sealing seats are respectively welded on the top cover of the hot well, packing is respectively arranged in the packing boxes between the outer walls of the atmosphere legs and the inner walls of the sealing seats, the upper parts of the packing are respectively provided with a packing gland, and the flange of the packing gland is connected with the flange of the sealing seat through gland screws.

11. The flexible production system of polyester products according to claim 9, characterized in that: the hot well slag discharge port is respectively connected with a cleaning box feed inlet at the top of the cleaning box, the cleaning box comprises a horizontal barrel with one end closed, a cleaning box sealing cover capable of being opened and closed is hinged to the front end port of the cleaning box, a cleaning box jacket is coated on the periphery of the barrel of the cleaning box, a plurality of square filtering drawers which are sequentially superposed are arranged in an inner cavity of the cleaning box from top to bottom, frames on the left side and the right side of each square filtering drawer are respectively supported in guide chutes through rollers, each guide chute extends along the axial direction of the cleaning box and is respectively fixed on two sides of the inner wall of the cleaning box, an arc bottom drawer is arranged at the bottom of the inner cavity of the cleaning box, the bottom of the arc bottom drawer is supported at the bottom of the inner wall of the cleaning box through rollers, filter screens are respectively arranged at the bottoms of the arc bottom drawer and the square filtering drawers, and the mesh number of the lower filter screen is sequentially larger than that of the upper filter screen, the lower end of the feed inlet of the cleaning box points to the central area of the square filter drawer at the top layer, and the bottom center of the cleaning box is provided with a liquid discharge port of the cleaning box.