A conveying system for improving the flowability of PVC resin powder during conveying

Abstract

The utility model discloses a conveying system for improving flowability of PVC resin powder in conveying process, which comprises a hopper, a cyclone separator, a blast conveying system connected between the hopper and the cyclone separator, a vibrating screen connected with the cyclone separator through a first material conveying pipeline, and a storage device connected with the vibrating screen through a second material conveying pipeline. A vertical discharge pipe is connected to the discharge end of the hopper, and a first regulating valve is connected to the tank. A first steam humidification system is connected to the material conveying pipe section of the blast conveying system, a second steam humidification system is connected to the first material conveying pipeline, an online moisture analyzer is connected to the first conveying pipeline between the second steam humidification system and the vibrating screen, and an angle less than 90° is formed between the material conveying pipe section of the blast conveying system and the vertical discharge pipe of the hopper. The first steam humidification system and the hopper are arranged in sequence and at intervals along the feeding direction of the blast conveying system. The system can effectively improve the flowability of PVC resin powder in the conveying process.

Description

Technical Field

[0001] This utility model belongs to the field of PVC resin production and processing technology, and specifically relates to a conveying system for improving the flowability of PVC resin powder during the conveying process. Background Technology

[0002] In suspension polymerization, after the slurry undergoes centrifugation and fluidized bed drying, the resulting PVC resin powder exhibits irregular particle morphology and extremely low surface moisture content. This leads to significant static electricity buildup on the resin powder surface, resulting in poor flowability. This poor flowability causes a sharp increase in the pressure difference at the junction of the small hopper rotary discharge valve and the Roots blower's air delivery pipeline, causing a corresponding increase in the Roots blower's current and making the equipment prone to tripping.

[0003] When resin powder is conveyed in the drying system, its poor flowability becomes apparent. For example, frequent flow interruptions occur during packaging, and bags are often overloaded, severely impacting the packaging quality of the finished product. During pipeline transport, the constant friction between the resin powder and the inner wall of the pipe easily leads to plasticization of the powder, increasing the plasticizer content in the finished product and negatively affecting pipe molding. Furthermore, material breaks can occur during pipe processing, easily causing pipe fractures, which not only affects the quality of the final product but also hinders the improvement of product grade. Utility Model Content

[0004] This invention provides a conveying system for improving the flowability of PVC resin powder during the conveying process, thereby solving the technical problem of poor material flowability in existing systems.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A conveying system for improving the flowability of PVC resin powder during transportation includes a hopper, a cyclone separator, a blower conveying system connected between the hopper and the cyclone separator, a vibrating screen connected to the cyclone separator via a first conveying pipeline, and a storage device connected to the vibrating screen via a second conveying pipeline. The hopper discharge end is connected to a vertical discharge pipe, and a first regulating valve is connected to the tank. A first steam humidification system is connected to the conveying pipe section of the blower conveying system, and a second steam humidification system is connected to the first conveying pipeline. An online moisture analyzer is connected to the first conveying pipeline between the second steam humidification system and the vibrating screen. The conveying pipe section of the blower conveying system forms an angle of less than 90° with the vertical discharge pipe of the hopper. The first steam humidification system and the hopper are arranged sequentially and at intervals along the feeding direction of the blower conveying system.

[0006] Furthermore, the first steam humidification system includes a first steam pipeline, a second regulating valve and a steam-water separator connected sequentially along the steam conveying direction to the first steam pipeline, and a steam ejector connected to the end of the first steam pipeline; the steam ejector is connected to the material conveying pipe section of the blower conveying system.

[0007] Furthermore, a first online humidity measuring and analyzing device is connected to the material conveying pipe section of the blower conveying system, and the first online humidity measuring and analyzing device is connected to the material conveying pipe section between the steam ejector and the hopper.

[0008] Furthermore, the second humidification system includes a mixer and a compressed air pipeline, a second steam pipeline, and an exhaust pipeline respectively connected to the mixer; the exhaust pipeline is connected to a steam injection ring at its end, the steam injection ring is connected to a first material conveying pipeline, the exhaust pipeline is provided with a first shut-off valve, the compressed air pipeline is connected with a third regulating valve, and the second steam pipeline is connected with a fourth regulating valve.

[0009] Furthermore, a second online humidity measuring and analyzing device is connected to the exhaust line between the steam injection ring and the first shut-off valve.

[0010] Furthermore, an external discharge line is connected to the exhaust line between the mixer and the first shut-off valve, and a second shut-off valve is connected to the external discharge line.

[0011] Furthermore, a pneumatic air hammer is fitted onto the steam injection ring.

[0012] Furthermore, a discharge valve is connected to the second conveying pipeline.

[0013] Furthermore, the cyclone separator's drain outlet is connected in sequence to a bag filter and an induced draft fan via pipelines.

[0014] Furthermore, the blower delivery system includes a Roots blower, a heat exchanger, and an air filter connected in sequence via pipelines.

[0015] Compared with the prior art, the beneficial effects of this utility model are: During the feeding process from the hopper to the cyclone separator, the system employs a primary steam humidification system to humidify the air supplying the PVC resin powder, increasing its humidity, reducing static electricity buildup, and improving its flowability. Simultaneously, the conveying pipe section of the blower system forms a structural design with an angle of less than 90° between it and the vertical discharge pipe of the hopper, making the material at the hopper discharge end easier to move by the airflow, further increasing its flowability and avoiding the need for Roots blower shutdown. On the primary conveying pipe between the cyclone separator discharge end and the vibrating screen, a secondary steam humidification system further humidifies this section, increasing its flowability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system connection of this utility model.

[0017] Among them, 1-hopper; 2-cyclone separator; 3-vibrating screen; 4-first regulating valve; 5-Roots blower; 6-heat exchanger; 7-air filter; 8-first steam pipeline; 9-second regulating valve; 10-steam-water separator; 11-steam ejector; 12-first online humidity measuring and analyzing device; 13-bag dust collector; 14-induced draft fan; 15-mixer; 16-compressed air pipeline; 17-second steam pipeline; 18-exhaust pipeline; 19-steam injection ring; 20-pneumatic air hammer; 21-third regulating valve; 22-fourth regulating valve; 23-first shut-off valve; 24-second shut-off valve; 25-online moisture analyzer; 26-discharge valve; 27-fifth regulating valve; 28-second online humidity measuring and analyzing device. Detailed Implementation

[0018] The preferred embodiments of this utility model will be described below with reference to the accompanying drawings.

[0019] like Figure 1 As shown, a conveying system for improving the flowability of PVC resin powder during transportation is described. The system includes a hopper 1, a cyclone separator 2, a blower conveying system, a vibrating screen 3, and a storage device 3. The blower conveying system feeds the PVC resin powder from the hopper 1 into the cyclone separator 2. After separation and screening, the cyclone separator 2 feeds the material into the vibrating screen 3. After separation by the vibrating screen 3, the material is fed into the storage device 3, which is typically a silo. The material discharged from the silo is then bagged. The first key improvement of this system is the addition of a first steam humidification system to the conveying pipe section of the blower conveying system to humidify the introduced air, which then blows the material for transportation. The second key improvement is the addition of a second steam humidification system and an online moisture analyzer to the conveying line between the cyclone separator 2 and the vibrating screen 3. The third key improvement is to create an angle of less than 90° between the conveying pipe section of the blower conveying system and the vertical discharge pipe of the hopper 1, increasing the flowability of the pneumatically conveyed material.

[0020] The PVC resin powder after being dried in a fluidized bed is fed into hopper 1 for temporary storage; a vertical discharge pipe is connected to the discharge port at the lower end of hopper 1, and a first regulating valve 4 is connected to the vertical discharge pipe. The first regulating valve 4 is an electric valve.

[0021] The blower conveying system includes a Roots blower 5, a heat exchanger 6, and an air filter 7 connected in sequence via a conveying pipe. The heat exchanger 6 cools the air introduced by the Roots blower 5; the air filter 7 purifies the air, removing any impurities and contaminants that may be present. The conveying pipe leading out of the discharge port of the air filter 7 is connected to the inlet of the cyclone separator 2; the angle between this conveying pipe section and the end of the vertical discharge pipe of the hopper 1 is controlled to be less than 90°, preferably controlled to be 60°.

[0022] The first steam humidification system is connected to the feed pipe section of the blower conveyor system between the air filter 7 and the hopper 1. The steam for the first steam humidification system can be byproduct steam from other production processes or steam provided by an additional steam generator; the supplied steam pressure is controlled between 0.01 and 0.2 MPa. The steam pressure for the second steam humidification system is also selected to be between 0.01 and 0.2 MPa. The first steam humidification system includes a first steam pipeline 8, a second regulating valve 9 and a steam-water separator 10 connected sequentially along the steam conveying direction to the first steam pipeline 8, and a steam ejector 11 connected to the end of the first steam pipeline 8. The steam ejector 11 is connected to the feed pipe section of the blower conveyor system, specifically between the air filter 7 and the hopper 1. The number of steam ejectors 11 used is flexibly set according to requirements. The first steam pipeline 8 is connected to the byproduct steam outlet or the steam generator outlet. The second regulating valve 9 is an automatic regulating valve. It is electrically connected to the first regulating valve 4. When the first regulating valve 4 is closed, the control system controls the second regulating valve 9 to close, thus preventing increased humidity in the conveying air when there is no material being conveyed. The second regulating valve 9 is used to regulate the steam flow rate. A first online humidity analyzer 12 is connected to the conveying pipe section of the blower conveying system. The first online humidity analyzer 12 is connected to the conveying pipe section between the steam ejector 11 and the hopper 1. The first online humidity analyzer 12 continuously monitors the humidity of the humidified air and, within the range of this monitoring, controls the opening of the second regulating valve 9. For example, if the detected air humidity deviates from the set range, the system automatically adjusts the opening of the second regulating valve 9 to stably control the air humidity between 40% and 45%. The steam-water separator 10 is used to remove water, ensuring the steam is dry. A drain pipe is connected to the bottom of the steam-water separator 10, and a control valve is connected to the drain pipe. The drain pipe is connected to an external water collection tank or other water circuit.

[0023] A first conveying pipeline connects the bottom of the cyclone separator 2 to the vibrating screen 3. The drain outlet of the cyclone separator 2 is connected to a bag filter 13 and an induced draft fan 14 via the pipeline. Smaller particles separated by the cyclone separator 2 are captured and collected by the bag filter 13, while the treated exhaust gas is discharged to the external environment via the induced draft fan 14. Powder with the required particle size is conveyed to the vibrating screen 3 through a fifth regulating valve 27 opened on the first conveying pipeline for secondary separation and impurity removal, further improving the purity and quality of the product. The fifth regulating valve 27 is an electric valve.

[0024] The second humidification system includes a mixer 15 and a compressed air line 16, a second steam line 17, and an exhaust line 18, all connected to the mixer 15. The mixer 15 can be a separately installed steam-water separator. The compressed air line 16 and the second steam line 17 can be connected to the air inlet of the mixer 15 via a tee pipe, or they can be connected separately with matching interfaces. A drain line is connected to the bottom of the mixer 15, and a self-regulating valve or an electrically controlled valve is connected to the drain line for drainage control. Alternatively, the mixer 15 can be a single empty tank to create a space for thorough mixing of air and steam. A steam injection ring 19 is connected to the end of the exhaust line 18, and the steam injection ring 19 is connected to the first conveying line. The steam injection ring 19 is a ring-shaped pipe structure with multiple nozzles connected along the ring. During installation, the nozzles are installed obliquely on the outside of the first conveying line, so that the gas is injected into the inside of the first conveying line. The steam injection ring 19 can make the steam relatively uniformly injected into the inside of the first conveying line along the circumference of the pipe, so as to promote the material to fully remove the humid air. A pneumatic air hammer 20 is fitted on the steam injection ring 19 to prevent nozzle clogging. The pneumatic air hammer 20 can be connected and fixed with an external support frame or fixed on the pipeline. The exhaust line 18 is equipped with a first shut-off valve 23, which is an electrically controlled valve. A second online humidity measuring and analyzing instrument 28 is connected to the exhaust line 18 between the steam injection ring 19 and the first shut-off valve 23. This analyzer is used to detect the humidity of the mixed air and feed it back to the control system. A third regulating valve 21 is connected to the compressed air pipeline 16. The third regulating valve 21 is a self-regulating regulating valve. The compressed air pipeline 16 is connected to an external compressed air source, specifically an air pump, blower, or other air supply equipment. The exhaust end of the air pump or other equipment should be connected to a separate air filter 7 to filter and remove impurities from the compressed air. A fourth regulating valve 22 is connected to the second steam pipeline 17. The fourth regulating valve 22 is a self-regulating regulating valve. The steam in the second steam pipeline 17 can be provided by the steam source of the first steam supply system or by other steam sources. An external discharge pipeline is connected to the exhaust pipeline 18 between the mixer 15 and the first shut-off valve 23. A second shut-off valve 24 is connected to the external discharge pipeline. When the humid air supply is stopped, the humid air can be temporarily discharged by closing the first shut-off valve 23 and opening the second shut-off valve 24.

[0025] An online moisture analyzer 25 is connected to the first conveying pipeline between the second steam humidification system and the vibrating screen 3. The online moisture analyzer 25 continuously monitors the humidity of the PVC powder passing through the first conveying pipeline. The control system controls the opening of the third regulating valve 21 and the fourth regulating valve 22, and also controls the first shut-off valve 23 and the second shut-off valve 24 accordingly. The control system also receives feedback from the closing action of the fifth regulating valve 27, and controls the first shut-off valve 23 and the second shut-off valve 24 accordingly.

[0026] The second conveying pipeline is connected to a discharge valve 26, which is used to control the on / off connection between the vibrating screen 3 and the storage device 3.

[0027] The valve components and other components or equipment that need to be regulated in this system are connected to the control system, which performs comprehensive control. The control system is a DCS system.

[0028] The working process and principle of this utility model are as follows: During equipment startup, the Roots blower 5 is turned on first, and outside air immediately enters the air heat exchanger 6. After being cooled in the heat exchanger 6, the air is sent to the filter for purification, removing any impurities and contaminants. After the purification process is complete, the second regulating valve 9 is opened, and steam first passes through the steam-water separator 10 for dehydration. After ensuring the steam is dry, it enters the steam ejector 11, where it is thoroughly mixed with the purified air to humidify it.

[0029] The humidified air then enters the first online humidity analyzer 12 for humidity testing. This analyzer establishes a control linkage with the second regulating valve 9. When the air humidity deviates from the set range, the system automatically adjusts the opening of the second regulating valve 9 to stabilize the air humidity between 40% and 45%. Once the humidity reaches the acceptable standard, the resin powder from the fluidized bed drying process enters the hopper 1 for storage. Subsequently, the resin powder is fed along the vertical discharge pipe under the control of the first regulating valve 4. During this process, the powder is conveyed to the cyclone separator 2 in the packaging process by the power generated by the humidified air. In case of any abnormality, such as the first regulating valve 4 in the hopper 1 stopping feeding, the control system immediately closes the second regulating valve 9 to prevent the resin powder from exceeding the moisture limit due to over-humidification.

[0030] After entering the packaging process, the cyclone separator 2 first performs pretreatment on the resin powder. During this process, smaller particles are captured and collected by a bag filter, while the treated exhaust gas is discharged into the environment through the induced draft fan 14. Powder with the required particle size is conveyed to the vibrating screen 3 through the opening of the fifth regulating valve 27 for secondary separation and impurity removal, further improving the purity and quality of the product.

[0031] During the feeding operation of the cyclone separator 2, the third regulating valve 21 on the compressed air pipeline 16 is opened and adjusted to 40% opening, allowing compressed air to enter the mixer 15. Simultaneously, the first shut-off valve 23 is opened to allow the compressed air to pass smoothly into the online humidity detector 2, where the initial humidity of the compressed air is measured. This humidity detector establishes a control relationship with the fourth regulating valve 22 on the second steam pipeline 17, automatically triggering the opening and closing of the fourth regulating valve 22 based on real-time humidity analysis data. After 10 seconds of operation, the fourth regulating valve 22 switches to automatic adjustment mode, gradually increasing its opening at a rate of 1% per second. At the same time, the drain pipe at the bottom of the mixer 15 is opened to promptly remove condensate generated during steam atomization, ensuring that the mixing effect is not affected.

[0032] After the above operations, the compressed air is humidified by steam in mixer 15. The humidified compressed air is then analyzed by humidity meter 2 to ensure that its humidity is stably maintained between 20-30%. Next, the humidified compressed air acts on the resin powder, and is detected by online moisture analyzer 25. If the resin moisture content is kept below 0.35%, the third regulating valve 21 maintains its current opening; if the resin moisture content further decreases to below 0.1%, the opening of the third regulating valve 21 is adjusted to 55%, and the humidity measurement conditions of the second online humidity analyzer 28 are set to 30-35%. Under such humidity conditions, the compressed air is evenly dispersed on the surface of the resin powder by steam jet ring 19, effectively reducing the electrostatic interaction between the resin powder particles and significantly improving its flowability, thereby improving the efficiency and quality of subsequent processing and packaging. In addition, to prevent the steam jet ring 19 from clogging and affecting the humidification effect, the pneumatic air hammer 20 connected to the spray ring of the cyclone separator 2 pipeline automatically taps 3 times every 300 seconds to ensure the normal operation of the spray ring. In the event of an abnormal situation, such as the fifth regulating valve 27 on the cyclone separator 2 closing and stopping the feeding, the control system immediately closes the first shut-off valve 23 and opens the second shut-off valve 24 at the same time, so that the steam in the mixer 15 can be discharged to the outside, avoiding the accumulation of steam that could cause the resin powder to exceed the moisture limit and affect the product quality.

[0033] The above description is merely a preferred embodiment of this utility model and does not constitute a limitation thereof. Within the technical spirit and principle framework of this utility model, any modifications, equivalent substitutions, and improvements made based on this embodiment should be included within the protection scope of this utility model.

Claims

1. A conveying system for improving the flowability of PVC resin powder during conveying, comprising a hopper, a cyclone separator, a blower conveying system connected between the hopper and the cyclone separator, a vibrating screen connected to the cyclone separator via a first conveying pipeline, and a storage device connected to the vibrating screen via a second conveying pipeline, wherein the discharge end of the hopper is connected to a vertical discharge pipe, and a first regulating valve is connected to the tank body, characterized in that, A first steam humidification system is connected to the conveying pipe section of the blower conveying system, and a second steam humidification system is connected to the first conveying pipe. An online moisture analyzer is connected to the first conveying pipe between the second steam humidification system and the vibrating screen. The conveying pipe section of the blower conveying system forms an angle of less than 90° with the vertical discharge pipe of the hopper. The first steam humidification system and the hopper are arranged sequentially at intervals along the feeding direction of the blower conveying system.

2. The conveying system as described in claim 1, characterized in that, The first steam humidification system includes a first steam pipeline, a second regulating valve and a steam-water separator connected sequentially along the steam conveying direction to the first steam pipeline, and a steam ejector connected to the end of the first steam pipeline; the steam ejector is connected to the material conveying pipe section of the blower conveying system.

3. The conveying system as described in claim 2, characterized in that, The blower conveying system is equipped with a first online humidity measuring and analyzing device on the conveying pipe section between the steam ejector and the hopper.

4. The conveying system as described in claim 1, characterized in that, The second steam humidification system includes a mixer and a compressed air pipeline, a second steam pipeline, and an exhaust pipeline connected to the mixer respectively; the exhaust pipeline is connected to a steam injection ring at its end, the steam injection ring is connected to a first material conveying pipeline, the exhaust pipeline is provided with a first shut-off valve, the compressed air pipeline is connected to a third regulating valve, and the second steam pipeline is connected to a fourth regulating valve.

5. The conveying system as described in claim 4, characterized in that, A second online humidity measuring and analyzing device is connected to the exhaust line between the steam injection ring and the first shut-off valve.

6. The conveying system as described in claim 4, characterized in that, An external discharge line is connected to the exhaust line between the mixer and the first shut-off valve, and a second shut-off valve is connected to the external discharge line.

7. The conveying system as described in claim 4, characterized in that, A pneumatic air hammer is fitted onto the steam injection ring.

8. The conveying system as described in claim 1, characterized in that, A discharge valve is connected to the second material conveying pipeline.

9. The conveying system as claimed in claim 1, characterized in that, The cyclone separator's drain outlet is connected in sequence to a bag filter and an induced draft fan via pipelines.

10. The conveying system as claimed in claim 1, characterized in that, The blower delivery system includes a Roots blower, a heat exchanger, and an air filter connected in sequence via pipelines.

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