A pta slurry preparation and delivery pipeline flushing device

Abstract

The utility model discloses a PTA slurry preparation and conveying pipeline flushing device, including PTA big storehouse, trousers three ways, screw conveyer, rotary valve, PTA slurry preparation jar, conveying pump, buffer jar, agitator, flush pump and relevant pipeline valve etc., PTA big storehouse sets up nearby, trousers three ways auxiliary powder smooth discharge, and screw conveyer realizes different supplier PTA according to proportion mixing through the adjustment rotating speed, and after the metering, enter the preparation jar with EG and prepare into slurry, and conveying pump sends slurry to esterification reactor, and long distance conveying uses big bending radius elbow pipe to reduce resistance, and pipeline is equipped with multiple flushing import and export, and is washed with the cooperation sequence on -off valve, and buffer jar and agitator prevent powder settlement, and flushing fluid is accurate backflow through frequency conversion pump, reduces the influence to slurry density, solves different supplier PTA mixing and long distance conveying pipeline blockage problem, reduces the cost, guarantees production and product quality.

Description

Technical Field

[0001] This utility model relates to PTA slurry processing equipment in the field of PET production, specifically a PTA slurry preparation and conveying pipeline flushing device, which is used to achieve accurate preparation, stable conveying and efficient pipeline flushing of PTA slurry, ensuring smooth PET production process and product quality. Background Technology

[0002] In the PET production process, PTA, as a core raw material, needs to be mixed with ethylene glycol (EG) in a specific ratio in a slurry preparation tank to form a PTA+EG slurry of a predetermined density, which is then transported to the esterification reactor for chemical reaction. In the traditional model, the slurry preparation system is located within the polyester building. Purchased PTA powder is first transported to the PTA feeding area of ​​the polyester unit, then conveyed via a chain conveyor to the PTA daily feed silo. After precise metering, the PTA powder is added to the preparation tank and mixed with EG. The qualified slurry is then pumped to the esterification reactor via a screw pump. However, this process has significant drawbacks: firstly, the long-distance transportation of PTA powder not only increases the investment and maintenance costs of the chain conveyor, but the dust generated during preparation can also pose safety hazards, threatening the safety of personnel and equipment on the production site. Secondly, while placing the PTA slurry preparation system externally within the polyester production unit can reduce some costs, the distance between the preparation area and the polyester unit varies, resulting in some PTA+EG slurry transport pipelines exceeding 100 meters. To address pipeline blockage, conventional flushing with ethylene glycol (EG) is used. However, during long-distance transport, large-scale EG flushing significantly alters the slurry density, affecting the esterification reaction and leading to product quality fluctuations that fail to meet production demands. Simultaneously, the challenge of properly mixing PTA from different suppliers to prepare the slurry needs to be resolved. Currently, existing patent literature (such as authorization publication numbers CN 215783337 U and CN 213118482 U) does not document solutions to problems such as PTA mixing ratio control and the impact of long-distance pipeline flushing on slurry quality. Summary of the Invention

[0003] This utility model provides a PTA slurry preparation and conveying pipeline flushing device, which aims to solve the problems of high PTA conveying cost, dust hazards, difficulty in controlling the mixing ratio of PTA from different suppliers, and the impact of long-distance pipeline flushing on slurry quality in the prior art.

[0004] To achieve the above objectives, this utility model is implemented through the following technical solution: This utility model discloses a PTA slurry preparation and conveying pipeline flushing device, which includes multiple sets of pipeline equipment. From top to bottom, each set of pipeline equipment includes a large PTA silo, a tee pipe, a screw conveyor, a rotary valve or weighing scale, and a PTA slurry preparation tank. The large silo is located in the PTA feeding area. The PTA silo has a powder outlet at its bottom, which connects to the inlet of a three-way pipe. This three-way pipe has two outlets, each connected to a screw conveyor. The outlets of these screw conveyors are connected to the inlets of a rotary valve. The PTA slurry preparation tank has an EG inlet, a flushing EG inlet I, and two powder inlets at its top. The rotary valve outlets in the same pipeline are connected to the powder inlets of different PTA slurry preparation tanks. The bottom of each PTA slurry preparation tank has at least one slurry outlet, and at least one of these outlets is connected to a PTA and EG slurry delivery pump I. The PTA and EG slurry delivery pump I is connected via a PTA slurry delivery pipeline. The esterification reactor has a slurry inlet, and the top of the esterification reactor is connected to the PTA slurry preparation tank via a PTA slurry return pipe. Multiple flushing EG inlets II with on / off valves are evenly distributed on the PTA slurry delivery pipe and the PTA slurry return pipe, and each flushing EG inlet II is connected to a flushing EG pipe. A flushing EG outlet with an on / off valve is located near the slurry inlet of the esterification reactor. The flushing EG outlet is connected to a PTA and EG slurry buffer tank with a stirrer via a flushing EG return pipe I. At least one flushing liquid delivery pump II is connected to the bottom outlet of the PTA and EG slurry buffer tank, and the flushing liquid delivery pump II is connected to the flushing EG inlet I of the PTA slurry preparation tank via the flushing EG return pipe II.

[0005] Multiple EG flushing inlets are evenly distributed on the PTA and EG slurry conveying pipelines. Each inlet is connected to an external switch valve. Near the slurry inlet of the esterification reactor, there is an EG flushing outlet, which is also connected to an external switch valve, so as to facilitate flexible control of the flushing operation and the discharge of the flushing liquid.

[0006] Preferably, a shut-off valve is connected to the bottom of the discharge port, and an expansion joint is connected to the bottom of the shut-off valve. The screw conveyor 3 is connected to the discharge port of the tee pipe through the expansion joint.

[0007] Preferably, the included angle between the two outlets of the tee tube is less than or equal to the angle of repose of the PTA powder.

[0008] Preferably, each of the discharge ports is provided with a fluidized N2 interface.

[0009] Preferably, two screw conveyors in each group of pipeline equipment are arranged longitudinally in a staggered manner.

[0010] Preferably, the PTA slurry conveying pipeline is equipped with a slurry mass flow meter with remote transmission function, and the slurry mass flow meter is equipped with a density transmitter.

[0011] Preferably, a control valve is provided between the PTA slurry preparation tank and the PTA and EG slurry delivery pump I, and a check valve is provided at the outlet end of the PTA and EG slurry delivery pump I.

[0012] Preferably, the volume of the PTA and EG slurry buffer tank is 3 to 4 times the volume of the PTA slurry conveying pipeline.

[0013] Preferably, the flushing fluid delivery pump II9 is ​​driven by a variable frequency drive to control the flow rate of EG and PTA slurry returning to the PTA slurry preparation tank to maintain 1 cubic meter per hour.

[0014] Preferably, the EG inlet of the PTA slurry preparation tank is simultaneously connected to recycled EG and fresh EG pipelines to introduce EG from different sources. Beneficial effects

[0015] (a) Cost and safety optimization By placing the large PTA silo close to the PTA feeding area, the conveying distance of the chain conveyor is shortened, reducing investment in the chain conveyor (such as a reduction in the number of equipment and installation complexity) and maintenance costs (reduced maintenance frequency and spare parts consumption). At the same time, the amount of dust generated during long-distance transport of PTA powder is reduced, thereby reducing the risk of safety hazards caused by dust accumulation, optimizing the safety environment of the production site, and ensuring the safety of personnel and equipment.

[0016] (ii) Precise control of mixing ratio Each pipeline system consists of two longitudinally staggered screw conveyors. Based on the same conveying capacity per revolution, adjusting the speed allows for precise control of the conveying volume of PTA powder from different suppliers, enabling proportional mixing of PTA from multiple suppliers. Combined with precise metering and dispensing via rotary valves, this ensures a stable proportion of PTA powder entering the PTA slurry preparation tank, laying the foundation for preparing consistent-quality PTA+EG slurry and meeting the raw material stability requirements of PET production.

[0017] (III) Ensuring Stability During Transportation The slurry mass flow meter on the PTA slurry conveying pipeline monitors the slurry flow and density in real time. If any abnormality occurs, such as flow fluctuations or density deviations from the set value, the speed of PTA and EG slurry conveying pump I or related valves can be adjusted in a timely manner to ensure stable conveying parameters. Control valves between the conveying pump and the preparation tank, as well as the check valve at the outlet, prevent slurry backflow and ensure stable conveying direction and flow. For long-distance conveying, reasonable pipeline design, such as the selection of bends, combined with flow monitoring and control, reduces PTA powder settling, ensures slurry conveying efficiency and quality, and provides qualified raw materials for the stable esterification reaction.

[0018] (iv) Pipeline flushing is efficient and has low impact The PTA slurry delivery pipeline and the PTA slurry return pipeline are equipped with flushing EG inlets II and outlets. By sequentially opening the valves, the pipelines are thoroughly flushed to remove residual slurry and prevent blockages. The flushing fluid flows into the PTA and EG slurry buffer tanks for temporary storage. An agitator prevents PTA sedimentation, and a frequency-controlled flushing fluid delivery pump II precisely controls the return flow to the PTA slurry preparation tank at a rate of approximately 1 cubic meter per hour. This allows for the recovery and reuse of EG from the flushing fluid and minimizes its impact on the slurry density in the preparation tank, ensuring stable esterification reaction results and product quality. The buffer tank has a volume 3-4 times that of the delivery pipeline, providing ample buffering capacity to accommodate varying flushing volumes. Attached Figure Description

[0019] Figure 1 This utility model includes a partial schematic diagram of the device structure.

[0020] Figure 2 Top view of part of the device structure of this utility model.

[0021] Figure 3 This utility model presents a schematic diagram of the structure of a three-way pipe for underwear.

[0022] Figure 4 This utility model presents a block diagram illustrating the flushing principle of a PTA slurry conveying pipeline. Detailed Implementation

[0023] The following will refer to the appendix in the embodiments of this utility model. Figure 1-4 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] In the description of the utility model, it should be noted that the terms "upper", "lower", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model.

[0025] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] It includes multiple sets of pipeline equipment, each set consisting of, from top to bottom: PTA silo 1, tee pipe 2, screw conveyor 3, rotary valve 4, and PTA slurry preparation tank 5; it is also equipped with PTA and EG slurry transfer pump I 6, PTA and EG slurry buffer tank with agitator 8 7, flushing fluid transfer pump II 9, esterification reactor 10, PTA slurry transfer pipeline 11, PTA slurry return pipeline 12, slurry mass flow meter with remote transmission function and density transmitter 13, EG flushing pipeline 14, EG flushing return pipeline I 15, and EG flushing return pipeline II 16. Among them, flushing fluid transfer pump II 9 and PTA and EG slurry transfer pump I 6 are both single screw pumps.

[0027] PTA Large Storage Bin 1: As a PTA powder storage unit, it has a powder outlet at the bottom, which is connected to the inlet 2.1 of the tee pipe 2. It is used to temporarily store PTA powder from different suppliers. Multiple units can be flexibly set up according to the production scale and the number of suppliers. They can be arranged close to the PTA feeding area to shorten the chain conveyor distance and reduce conveying costs and dust generation.

[0028] T-joint 2: The inlet 2.1 receives the powder output from the PTA silo 1, and has two outlets 2.2, each connected to a screw conveyor 3; the bottom of the outlet 2.2 is connected to a shut-off valve, and below it is an expansion joint. The screw conveyor 3 is connected to it through the expansion joint, which serves to divert the PTA powder to different conveying channels. The included angle between the two outlets 2.2 is less than or equal to the PTA powder's angle of repose, and the outlet 2.2 is connected to the fluidization N2 interface 2.3 to ensure smooth powder flow and avoid bridging and blockage.

[0029] Screw conveyor 3: Each screw conveyor corresponds to a discharge port 2.2 of the tee pipe 2, which receives powder and then conveys it to the rotary valve 4; In each set of pipeline equipment, two screw conveyors 3 are arranged longitudinally in a staggered manner, and the conveying capacity per revolution is the same. By adjusting the speed (this is a conventional technology, which will not be described in this application), the conveying ratio of PTA powder from different suppliers can be precisely controlled to achieve the mixing of PTA from multiple suppliers as needed.

[0030] Rotary valve 4, also known as a metering scale, has its inlet connected to the outlet of screw conveyor 3, and its outlet connected to the powder inlet 5.1 of different PTA slurry preparation tanks 5. As a precise metering and distribution unit, it controls the amount of PTA powder entering each preparation tank to ensure a stable slurry ratio.

[0031] PTA slurry preparation tank 5: The top is equipped with an EG inlet 5.2, which is connected to recycled EG and fresh EG pipelines to introduce EG from different sources, a flushing EG inlet I 5.3, and two powder inlets 5.1 to receive PTA powder delivered by rotary valve 4; the bottom is equipped with at least one slurry outlet, at least one of which is connected to a PTA and EG slurry delivery pump I 6, which is used to mix PTA powder and EG to form a PTA+EG slurry of a predetermined density, and is the core unit for slurry preparation.

[0032] PTA and EG slurry delivery pump I6: As a power unit, it delivers the slurry in the PTA slurry preparation tank 5 to the slurry inlet of the esterification reactor 10 through the PTA slurry delivery pipeline 11; a control valve is installed between the pump and the PTA slurry preparation tank 5, and a check valve is installed at the outlet end to ensure stable delivery direction, prevent slurry backflow and facilitate pipeline flushing; together with the slurry mass flow meter 13, it achieves accurate and stable slurry delivery.

[0033] Esterification reactor 10: It receives PTA+EG slurry for esterification reaction and is a key reaction equipment in PET production; the top is connected to the PTA slurry preparation tank 5 through PTA slurry return pipe 12, which can realize slurry return regulation and ensure reaction stability.

[0034] PTA slurry conveying pipeline 11 and PTA slurry return pipeline 12: PTA slurry conveying pipeline 11 is used to convey slurry to esterification reactor 10, and PTA slurry return pipeline 12 realizes slurry return; both are evenly distributed with multiple flushing EG inlets II with switch valves, which are connected to flushing EG pipeline 14 for introducing flushing EG; a flushing EG outlet with a switch valve is provided near the slurry inlet of esterification reactor 10, which is connected to flushing EG return pipeline I 15 to form a pipeline flushing passage.

[0035] PTA and EG slurry buffer tank 7: connected to the EG flushing outlet via EG flushing return pipe I15, with a volume 3-4 times that of PTA slurry conveying pipe 11, serving as a temporary storage tank for flushing fluid; top equipped with a stirrer 8 to prevent the temporarily stored PTA slurry from settling; bottom outlet connected to flushing fluid conveying pump II9 to achieve flushing fluid recycling and reuse.

[0036] Rinsing fluid transfer pump II9: It is preferably driven by a variable frequency drive and is connected to the rinsing EG inlet I5.3 of the PTA slurry preparation tank 5 through the rinsing EG return pipeline II16. It can accurately control the flow rate of EG+PTA slurry returning to the preparation tank to stabilize at 1 cubic meter / hour, thereby reducing the impact of rinsing on the slurry density.

[0037] Slurry mass flow meter 13: Installed on PTA slurry conveying pipeline 11, it has remote transmission function and built-in density transmitter to monitor slurry flow and density in real time, provide data support for the control of the conveying process, and ensure the stability of slurry conveying parameters.

[0038] Flushing EG pipeline 14, flushing EG return pipeline I 15, and flushing EG return pipeline II 16: Flushing EG pipeline 14 provides EG medium for pipeline flushing; Flushing EG return pipeline I 15 realizes the transportation of flushing fluid from the delivery / return pipeline to the buffer tank 7; Flushing EG return pipeline II 16 completes the return of flushing fluid from the buffer tank 7 to the preparation tank 5, thus constructing a flushing fluid circulation path.

[0039] Multiple EG flushing inlets are evenly distributed on the PTA and EG slurry conveying pipeline 11. Each inlet is connected to an external switch valve. Near the slurry inlet of the esterification reactor 10, there is an EG flushing outlet, which is also connected to an external switch valve, so as to facilitate flexible control of the flushing operation and the discharge of the flushing liquid.

[0040] The EG flushing outlet is connected via piping to the PTA and EG slurry buffer tank, located near the esterification reactor 10. This buffer tank has a volume approximately 3-4 times that of the slurry delivery pipeline, ensuring ample buffering capacity. The buffer tank has a material inlet at the top and a material outlet at the bottom to meet different operational needs. The PTA and EG slurry buffer tanks are equipped with top-mounted agitators. These agitators have a frame structure that extends deep into the tank to the bottom, and their main function is to effectively prevent PTA powder settling. The slurry buffer tanks are normally kept empty and do not contain any material; the internal agitators are only activated when the tank is filled with PTA slurry.

[0041] like Figure 1 As shown in the figure, this embodiment refers to two different PTA suppliers, denoted as Supplier A and Supplier B, and two polyester production units, denoted as Unit A and Unit B. The specific configuration of the units is as follows: PTA Large Material Bin 1: Two bins are set up to store PTA powder from supplier A and supplier B respectively. They are located in the PTA feeding area with the feeding port adjacent to the large material bin, which reduces the conveying distance of the chain conveyor and reduces dust generation and equipment costs during the conveying process.

[0042] T-joint 2: One t-joint 2 is connected to the outlet of each PTA silo 1, for a total of 2; the inlet 2.1 of each t-joint 2 is seamlessly connected to the outlet of the corresponding silo, and two outlets 2.2 are provided, with the included angle set at 60° to match the repose angle of the PTA powder, which can be adjusted according to the actual powder characteristics; an isolation valve is installed at the bottom of the outlet 2.2, connected to an expansion joint, and each outlet 2.2 is provided with a fluidized N2 interface 2.3 to connect to a nitrogen source to ensure smooth powder flow.

[0043] Screw conveyor 3: Each pair of two discharge ports 2.2 of the thong pipe 2 is connected to one screw conveyor 3, for a total of 4; each set of pipeline equipment corresponds to a large silo and the two screw conveyors 3 of the subsequent equipment are arranged longitudinally in a staggered manner. If the conveying capacity per revolution is set to a fixed value, such as 1 kg / revolution according to the production scale, the speed is adjusted by the frequency converter to control the conveying ratio of PTA powder from different suppliers.

[0044] Rotary valve 4: Four units are set up. The discharge port of each screw conveyor 3 is connected to the inlet of one rotary valve 4. The discharge ports of two rotary valves 4 corresponding to a large silo in the same group of pipeline equipment are respectively connected to the powder inlet 5.1 of the PTA slurry preparation tank 5 corresponding to the two sets of polyester production units, so as to realize the precise distribution of PTA powder to different preparation tanks.

[0045] PTA slurry preparation tank 5: Two tanks are configured, corresponding to the slurry preparation of Unit A and Unit B respectively; each PTA slurry preparation tank 5 has two powder inlets at the top 5.1 to receive PTA powder from the corresponding rotary valve 4 and EG inlet 5.2 to connect to the recycled EG pipeline and the fresh EG pipeline, and the EG source is introduced and the EG flushing inlet I is controlled by switching valves 5.3 to connect to the EG flushing return pipeline II 16; there are two slurry outlets at the bottom, one of which is connected to the PTA and EG slurry delivery pump I 6, and the other can be used as a spare or discharge port; a control valve is installed between the tank and the delivery pump to regulate the slurry output.

[0046] PTA and EG slurry transfer pump I6: Two units are installed. They are single screw pumps, which are respectively connected to the PTA slurry preparation tank 5 and PTA slurry transfer pipeline 11 of Unit A and Unit B. A check valve is installed at the outlet of the transfer pump to prevent slurry backflow and ensure stable conveying direction.

[0047] Esterification reactor 10: Two sets are arranged, corresponding to device A and device B respectively. They receive PTA+EG slurry from PTA slurry delivery pipeline 11 for esterification reaction. The top is connected to the corresponding PTA slurry preparation tank 5 through PTA slurry return pipeline 12. The pipeline is equipped with valves to adjust the amount of return slurry and stabilize the reaction process.

[0048] PTA slurry conveying pipeline 11 and PTA slurry return pipeline 12: Two sets are laid, corresponding to Unit A and Unit B respectively; Multiple flushing EG inlets II with switch valves are evenly arranged on the pipeline, such as one every 5 meters, all connected to flushing EG pipeline 14; A flushing EG outlet with a switch valve is set near the slurry inlet of esterification reactor 10, connected to flushing EG return pipeline I 15; The pipeline adopts a bend with a bending radius of at least 3.5 times the outer diameter of the pipeline to reduce conveying resistance.

[0049] PTA and EG slurry buffer tanks 7: Two are set up and arranged close to the esterification reactors 10 of Unit A and Unit B respectively; the volume is 3-4 times the volume of the corresponding PTA slurry conveying pipeline 11. For example, if the pipeline volume is V, the buffer tank volume is 3V-4V; a frame agitator 8 is installed on the top, and the agitator shaft extends into the bottom of the tank; there are two outlets at the bottom, one of which is connected to the flushing liquid conveying pump II 9, and the other can be used as a drain outlet.

[0050] Flushing fluid transfer pump II9: Two units are installed. They are single screw pumps driven by frequency converter. They are connected to the flushing EG inlet I5.3 of the corresponding PTA slurry preparation tank 5 through the flushing EG return pipeline II16, and the return flow rate is precisely controlled to 1 cubic meter / hour.

[0051] Slurry mass flow meter 13: One unit is installed on each PTA slurry conveying pipeline 11. It has a remote transmission function and a built-in density transmitter to monitor and transmit slurry flow and density data to the control system in real time.

[0052] Flushing EG pipeline 14, Flushing EG return pipeline I 15, Flushing EG return pipeline II 16: Flushing EG pipeline 14 is the main pipeline, supplying EG to the flushing EG inlet II of the two sets of delivery / return pipelines; Flushing EG return pipelines I 15 and II 16 are each provided in 2 sets, which are respectively connected to the corresponding buffer tank 7 and the flushing outlet, and the buffer tank 7 and the preparation tank 5, forming a flushing fluid circulation loop.

[0053] PTA powder conveying and mixing process: PTA powder from suppliers A and B is conveyed via a chain conveyor to the corresponding PTA bulk silo 1 for temporary storage.

[0054] When slurry preparation is required, the bottom powder outlet of the PTA silo 1 is opened, and the powder falls into the inlet 2.1 of the tee pipe 2. Nitrogen gas is introduced through the fluidizing N2 interface 2.3 to assist the powder to smoothly enter the two outlets 2.2, and then enter the screw conveyor 3 through the isolation valve and expansion joint.

[0055] Based on the production requirements for mixing ratios of PTA from different suppliers, such as supplier A:PTA supplier B = 2:3, the speed of the corresponding screw conveyor 3 is adjusted so that the conveying capacity per revolution is fixed. The mass ratio is controlled by the speed ratio, so that the two screw conveyors 3 convey PTA powder to the rotary valve 4 in a proportional manner.

[0056] After precise metering by rotary valve 4, the powder is distributed to the powder inlet 5.1 of the PTA slurry preparation tank 5 of the corresponding polyester production unit, completing the proportional mixing and conveying of PTA powder from multiple suppliers.

[0057] PTA+EG slurry preparation: PTA slurry preparation tank 5 is connected to EG inlet 5.2. Depending on production needs, recycled EG or fresh EG can be introduced and switched via valves to mix with the incoming PTA powder.

[0058] The PTA slurry preparation tank 5 can use a conventional stirring structure to fully stir the PTA and EG, so as to form a PTA+EG slurry with a predetermined density, such as ρ according to the requirements of PET production process, and complete the slurry preparation process.

[0059] PTA+EG slurry delivery: Open the control valve between the PTA slurry preparation tank 5 and the PTA and EG slurry transfer pump I6 to start the transfer process. Slurry transfer: The PTA+EG slurry enters the PTA and EG slurry transfer pump I6 through the bottom outlet of the PTA slurry preparation tank 5, and is then transported by this pump to the top inlet of the esterification reactor 10 through the PTA slurry transfer pipeline 11. During the transfer process, the slurry mass flow meter 13 monitors the flow rate and density in real time. If any abnormalities occur, such as a decrease in flow rate or density fluctuations, the pump speed can be adjusted in a timely manner or the pipeline problem can be investigated. During long-distance slurry transfer, using a bend with a bending radius of at least 3.5 times the outer diameter of the pipe can effectively reduce pipeline resistance.

[0060] Pipeline flushing: When performing pipeline flushing, first activate the flushing EG inlet valve on the side closest to the esterification reactor 10, hold it for a few seconds, and then close it. Then, sequentially open the adjacent flushing EG inlet valves facing away from the esterification reactor 10, holding each valve for a few seconds before closing it. By sequentially operating all the flushing EG inlet valves until a complete cycle of opening and closing is completed, a thorough flushing of the slurry delivery pipeline is achieved.

[0061] Specifically: When it is necessary to flush the PTA slurry delivery pipeline 11 or the PTA slurry return pipeline 12, first activate the flushing EG inlet valve on the side closest to the esterification reactor 10. EG enters the pipeline from the flushing EG pipeline 14, and after a few seconds, close the valve. Then, sequentially open the adjacent flushing EG inlet valves facing away from the esterification reactor 10, opening each valve for a few seconds and then closing it, until all flushing EG inlet valves have completed one round of opening and closing, achieving comprehensive flushing of the pipeline. The flushed EG+PTA mixture can flow into the PTA and G slurry buffer tank 7 through the flushing EG outlet and the flushing EG return pipeline I 15.

[0062] Finally, it should be noted that this utility model is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this utility model should be considered within the protection scope of this utility model.

Claims

1. A PTA slurry preparation and conveying pipeline flushing device, characterized in that, The package includes multiple sets of pipeline equipment. From top to bottom, each set of pipeline equipment includes a large PTA silo (1), a tee pipe (2), a screw conveyor (3), a rotary valve (4), and a PTA slurry preparation tank (5). The large silo (1) is located in the PTA feeding area. The bottom of the PTA silo (1) is provided with a powder outlet, which is connected to the inlet (2.1) of the tee pipe (2). The tee pipe (2) is provided with two outlets (2.2), and each outlet (2.2) is connected to a screw conveyor (3). The outlet of the screw conveyor (3) is connected to the inlet of a rotary valve (4). The top of the PTA slurry preparation tank (5) is provided with an EG inlet (5.2), a flushing EG inlet I (5.3), and two powder inlets (5.1). The outlet of the rotary valve (4) in the same pipeline equipment is connected to the powder inlet (5.1) of different PTA slurry preparation tanks (5). The bottom of the PTA slurry preparation tank (5) is provided with at least one slurry outlet, and at least one of the slurry outlets is connected to a PTA and EG slurry delivery pump I (6). The PTA and EG slurry delivery pump I (6) is connected to the slurry inlet of the esterification reactor (10) through a PTA slurry delivery pipe (11), and the top of the esterification reactor (10) is connected to the PTA slurry preparation tank (5) through a PTA slurry return pipe (12). Multiple flushing EG inlets II with switch valves are evenly distributed on the PTA slurry delivery pipe (11) and the PTA slurry return pipe (12), and the flushing EG inlets II are all connected to the flushing EG pipe (14). A flushing EG outlet with a switch valve is provided near the slurry inlet of the esterification reactor (10). The flushing EG outlet is connected to a PTA and EG slurry buffer tank (7) with a stirrer (8) via a flushing EG return pipe I (15). At least one flushing liquid transfer pump II (9) is connected to the bottom outlet of the PTA and EG slurry buffer tank (7). The flushing liquid transfer pump II (9) is connected to the flushing EG inlet I (5.3) of the PTA slurry preparation tank (5) via a flushing EG return pipe II (16).

2. The PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, The bottom of the discharge port (2.2) is connected to a shut-off valve, and an expansion joint is connected to the shut-off valve. The screw conveyor (3) is connected to the discharge port (2.2) of the tee pipe (2) through the expansion joint.

3. A PTA slurry preparation and conveying pipeline flushing device according to claim 1 or 2, characterized in that, The included angle between the two outlets (2.2) of the tee pipe (2) is less than or equal to the angle of repose of the PTA powder.

4. A PTA slurry preparation and conveying pipeline flushing device according to claim 1 or 2, characterized in that, Each of the discharge ports (2.2) is provided with a fluidized N2 interface (2.3).

5. The PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, Two screw conveyors (3) are arranged longitudinally in a staggered manner in each group of pipeline equipment.

6. The PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, The PTA slurry conveying pipeline (11) is equipped with a slurry mass flow meter (13) with remote transmission function, and the slurry mass flow meter (13) is equipped with a density transmitter.

7. The PTA slurry preparation and conveying pipeline flushing device according to claim 3, characterized in that, A control valve is provided between the PTA slurry preparation tank (5) and the PTA and EG slurry delivery pump I (6), and a check valve is provided at the outlet end of the PTA and EG slurry delivery pump I (6).

8. The PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, The volume of the PTA and EG slurry buffer tank (7) is 3 to 4 times the volume of the PTA slurry conveying pipeline (11).

9. The PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, The flushing fluid delivery pump II (9) is driven by a variable frequency drive to control the flow rate of EG and PTA slurry returning to the PTA slurry preparation tank (5) to be maintained at 1 cubic meter / hour.

10. A PTA slurry preparation and conveying pipeline flushing device according to claim 1, characterized in that, The EG inlet (5.2) of the PTA slurry preparation tank (5) is simultaneously connected to the recycled EG and fresh EG pipelines to introduce EG from different sources.

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