Polytetrafluoroethylene PTFE air flow dryer

Polytetrafluoroethylene resin, abbreviated as PTFE, is resistant to almost any concentration of strong bases, acids, oxidizers and solvents, and is known as “King of Plastics”. In recent years, along with the promotion of China's new infrastructure, as well as new energy, semiconductor, BIPV and other industries, the rapid development of the market demand for high-performance fluoropolymers continue to release, for PTFE market development to bring strong momentum. The application of PTFE resin in many fields such as electronic communications, photovoltaic power generation, industrial coatings, agricultural films, aerospace, medical devices, etc. has been expanding and deepening, further promoting the expansion of the market scale. The state attaches great importance to the development of new high-performance chemical materials and policy support, PTFE, as a high-performance fluoropolymer, is expected to benefit from the relevant industrial policies, accelerate the realization of domestic substitution, and further expand the market share.

Suspension method polytetrafluoroethylene (PTFE or F40 for short) is a white powdery material, which is made from tetrafluoroethylene polymer by pounding, grinding, washing and drying. The water content of PTFE after washing is about 35%, the particle size is about 150um, the final moisture must be dried to below 0.04% to meet the production requirements, and PTFE powder has strong adhesion, easy to agglomerate and stick to the wall at high temperatures, and easy to be formed into a ball after extrusion; the whiteness of the product and the cleanliness are required to be higher, and there are special requirements for its drying process.
Jinwang Drying has carried out process improvement and equipment development for the drying of PTFE suspension resin to make the production operation more convenient and simple, minimize the manual operation link, make the drying of PTFE more efficient and energy-saving, reduce the production cost, improve the product quality and production efficiency, reduce the contamination of the drying unit on the PTFE powder, and promote its application in more fields.

Working principle of PTFE suspension resin airflow dryer

PTFE suspension resin airflow dryer is characterized by good operating environment, automatic and continuous feeding and discharging, high cleanliness of products and low temperature of finished products.
The outside air enters into the venturi feeder after heating and purifying, which generates negative pressure suction and sucks the wet material into the air duct. The hot air carries the material into the airflow dryer for drying. The dried material enters the cyclone separator with the airflow for recovery. After the outside air is purified, cooled and de-misted, it enters the cooling section venturi feeder, and the recovered material from the cyclone separator is sucked into the air duct for cooling, and the cooled material is then collected by the cyclone separator to get the finished product.
 Due to the special nature of PTFE suspension resin, the dryer can not accumulate materials, the inner wall of the equipment are polished (roughness of 0.2um), equipment and pipeline connections without sharp corners, the duct turns with a large curvature radius pipe.

Polytetrafluoroethylene PTFE suspension resin air flow dryer performance characteristics

(1)High drying efficiency
Rapid drying: the hot airflow is directly in contact with the material, so that the material is dried instantly in the suspended state, and the drying time is short, generally only 2-3 seconds, which greatly improves the production efficiency. High-efficiency heat and mass transfer: As the material is suspended, it is in full contact with the hot airflow, and the contact area of gas and solid phases is large, which strengthens the process of heat and mass transfer, and it can quickly evaporate the moisture in the material and bring out the moisture, so as to realize high-efficiency drying.
(2)Good product quality
Drying uniformity: hot airflow can uniformly surround the material particles, so that it is heated uniformly, avoiding local overheating or drying insufficient, thus ensuring the quality stability of PTFE suspension resin after drying, to ensure the consistency of the product performance low water content: through the precise control of the drying temperature, wind speed and residence time and other parameters, can be reduced to the water content of PTFE suspension resin below 0.02%, to meet the requirements of the gao-end application fields. The water content of PTFE suspension resin can be reduced to less than 0.02% through precise control of parameters such as drying temperature and air speed.
High purity: Equipped with high efficient filtration system, the hot air and cold air entering the dryer are strictly filtered, which can reach the requirements of 100,000 class or 100 class or even sterile purification, effectively preventing impurities from mixing into the material and ensuring the high purity of the product, so that it can be better used in the field of high purity requirements, such as electronics, pharmaceuticals and so on.
(3)Precise temperature control
Wide temperature range: The heating system can make the temperature of the hot airflow reach a high level, and the zui high temperature is usually up to 280°C, which meets the temperature conditions required for drying PTFE suspension resin, meanwhile, in the cooling stage, it can effectively reduce the temperature of the material to below 30° C, which is convenient for subsequent packaging and storage. Precise que temperature control: Adopting advanced temperature control system, such as PLC or DCS remote control, it can realize precise que control and automatic section of drying temperature and cooling temperature, with high precision of temperature control to ensure that the drying and cooling process is carried out stably within the set temperature range, so as to ensure the stability and reliability of product quality.
(4)High degree of automation
Automatic control: Equipped with perfect automatic control system, it can realize automatic monitoring and precise control of parameters such as feeding volume, air intake, wind speed, temperature, pressure, etc., and can automatically adjust the running status of the equipment according to the preset parameter values, which reduces manual intervention and improves the stability of the production process and the consistency of product quality. Failure warning and protection: with motor overload protection, over-temperature automatic alarm and other functions, it can real-time monitor the operating condition of the equipment, and once the abnormal situation occurs, the system will immediately issue an alarm and take corresponding protective measures to avoid equipment damage and safety accidents, which guarantees the safe and stable operation of the equipment.
(5) High reliability of equipment
High-quality materials and components: the components in contact with materials and hot air are usually made of corrosion-resistant and high-temperature-resistant high-quality materials, such as 316L clean tube, 310S material or Hastelloy, etc., which ensures that the equipment operates stably in a long-term high-temperature, corrosive environment and prolongs the service life of the equipment. Good mechanical design: the structure of the equipment is reasonably designed with mechanically polished sanitary clean pipes and connected by flanges, which are easy to install, dismantle, clean and disinfect and sterilize; at the same time, taking into account the characteristics of PTFE, metal expansion joints are used for mechanical compensation to prevent the equipment from being deformed due to thermal expansion, and wooden brackets are used for fixing to reduce the heat loss, which improves the reliability and stability of the equipment.

Polytetrafluoroethylene PTFE suspension resin air dryer technology improvement

 (1) Purification of drying and cooling media Polytetrafluoroethylene PTFE production plant is a clean room, should be in line with GMP standards, the drying medium must be required to achieve a certain level of cleanliness, so the hot air, cold air are multi-stage purification. 

(2) Feeding system Feeding system is the key equipment of the whole set of PTFE air drying system, domestic air drying common feeding methods are venturi feeding and rotating equipment feeding two kinds of PTFE drying to venturi feeding is common. Due to the ordinary venturi feeder structure is too simple, no adjustment function, pressure loss, feed too much or agglomeration will affect the operation, serious cases in the venturi tube throat diameter of the formation of material, resulting in pipeline clogging, so it is difficult to realize the automation of a single Venturi feeder feeding, and at the same time, due to the nozzle position of the Venturi feeder is fixed, the improper design is easy to cause the feeding port or blocking the material spraying. Aiming at the shortcomings of the venturi feeder, Loncin Drying developed an adjustable feeding system, the nozzle position can be realized by increasing the gasket between the tapering section and the venturi feeder shell. Usually the nozzle position adjustment is only used in the trial stage, and it is basically unchanged after adjustment. Daily operation, when the output, pressure, material erection and so on changes through the adjustment of the bypass valve to adjust can realize the purpose of regulation. 

(3) Airflow drying main machine Air drying host try not to use right-angle elbow, it is appropriate to use the angle is greater than 120 °, large radius elbow, in order to reduce resistance, to prevent the accumulation of material. Material pipeline and equipment wall finish to 0.2um is better, so that the inner wall is not easy to stick material. 

(4) Discharge system Discharge using rotary discharge valve, will lead to lubricant contaminated material, and the rotor and the inner wall friction will produce a lot of lumps and pieces of waste, affecting the performance of the product. Jinwang Drying has developed a new type of automatic flap valve, which can realize sealing and continuous automatic discharging, and no waste material is produced.

 (5) Control system Polytetrafluoroethylene PTFE suspension resin air dryer adopts PLG for control, and at the same time increases two chain protection: ① electric heater and fan chain to protect the electric heater from overheating; ② condenser regulating valve and fan chain to prevent condenser from freezing, cold air, hot air induced draft fan adopts frequency conversion speed regulation, increasing the adjustability of the system.