Fanqun Spray granulation Dryer is an important equipment in the production process of PTC thermal ceramics, which is of high price, complex composition, difficult to use and maintain. The good operation of the equipment can not only ensure the normal production of PTC thermal ceramics, but also prolong the service life of the equipment and reduce the production cost, so it is necessary to operate the equipment correctly and to strengthen the maintenance. 1 Spray granulation dryer principle and composition granulation is a very important process in the production process of PTC thermal ceramics, the quality of the pellet directly affects the appearance, mechanical properties and resistance temperature characteristics of the PTC ceramic sheet. Granulation refers to adding a certain amount of adhesive in the grinding powder, evenly and after the formation of a granular powder, the powder has a good fluidity and ductility, so that in the press process can be a better strength, not easy delamination cracking film. In the industrial production of the use of spray drying granulation, the basic principle is the powder with a binder, spray into the granulation tower atomization, the tower of the droplet is dried into a granular powder tower, and then discharged from the bottom of the drying tower.

The company's pressure-type spray granulation dryer is mainly composed of feeding system, drying system, dust removal system, heating system and electrical system, and each system includes some related equipment. The feeding system consists of mixing barrels, filters, diaphragm pumps and spray guns. The ball mill two times the slurry from the ball mill transferred to the stirring bucket, the filter is pumped and transmitted by the diaphragm pump, and then through the spray gun into the drying tower. Slurry from the spray gun nozzle into the drying tower began the spray granulation drying process, the specific process is divided into three stages: (1) Slurry atomization. Slurry from the feeding system in the diaphragm pump pressure from the nozzle to press into the drying tower, the pressure of energy conversion to kinetic energy, slurry from the bottom up from the nozzle spray, forming a high-speed liquid film, liquid film split into droplets. The droplet size is inversely proportional to the pressure, and the capacity of the nozzle is in direct proportion to the square of the pressure. (2) Dry the particles into a ball. Fog particles and hot air in the way of mixing flow, hot air is through the top cover of the hot air distributor into the tower, the hot-air splitter produces a downward flow of air stream, droplets from the bottom up into the hot air stream. Droplet due to the effect of surface tension formed spherical, at the same time, because the droplet has a large surface area, wherein the water quickly evaporated and dried, and eventually contracted to form a dry spherical granular powder. (3) Particulate powder discharge. The formed spherical granular powder gradually settles in the drying tower, separates from the hot air, and the funnel cavity in the lower part of the tower makes the granular material assemble and unload from the discharging port. The finer particles are drawn together with the dry air by a suction machine connected to the upper funnel to enter the dedusting system. The drying system is composed of a blower, a drying tower and a suction machine for conveying hot air to the drying tower. Dedusting system is composed of high-efficient cyclone separator, bag filter, centrifugal fan and so on. The exhaust fan will feed the finer particles together with the dry air into an efficient cyclone. After effective separation, the finer granular material into the separator bottom of the collection tube recovery, the remaining containing a very small amount of fine particulate material exhaust from the centrifugal fan suction bag dust collector after another dust collection, to achieve the harmless treatment of exhaust gases, the final exhaust from the chimney discharged.

In addition, heating systems, such as electric heaters and gas-fired stoves, provide hot air for drying towers. Electrical control cabinets and sensors installed in the inlet and outlet monitoring temperature of the field sensor and other components of the electrical system to the entire spray granulation dryer monitoring and control of all major aspects to ensure the normal operation of the entire equipment. 2 daily operation and precautions during the daily production process, the necessary preparations should be made before the equipment is activated. First check the bearing and seal part of each device is loose, the lubricating oil condition of each machine part and the water, wind, slurry pipe valve and so on are in the desired position. Then turn on the power to check the voltage and the instrument is normal, and finally check the slurry in the mixing tank slurry quantity and concentration, etc., if there are problems should be promptly ruled out. Then turn on the blower, exhaust fan, and then open the heating switch began to heat up. When the discharge port temperature reaches the set temperature (generally 130 ℃ or so), start the material pump and dust removal system. When the pump pressure reaches 2MPa, open the gun and start granulation. After the equipment operation, should observe the atomization condition and the material pump working condition in time, if appears the blockage gun phenomenon needs to immediately clean or to replace the nozzle. After the normal operation of the equipment, it should also be timed to receive the material, regularly check the operation of each system, record the process parameters, and pay attention to clean the vibration filter sieve. At the end of granulation, the heating device should be shut down first to stop the gas engine running. Then close the gun valve, replace the gun, unscrew the nozzle and rinse it clean. When the inlet temperature is reduced to less than 100 ℃, the operation of the blower and the exhaust fan can be stopped. Then clean the drying tower and dust collector, close the dust collector and air hammer, and finally shut down the total power supply, complete production operation. In case of emergency, must immediately shut down the equipment, should first shut down the air blower and the material pump. If the Tuyu power outage, should pull out the gas machine, so that the tower natural cooling, and then open the sewage valve, drain slurry pipe slurry, and cleaning equipment. 3 Maintenance and Maintenance granulation is an important part of PTC production process, and maintaining the normal operation of equipment is the necessary condition to ensure the stability of PTC production. Regular cleaning, maintenance and maintenance help to identify problems in time, resolve potential failures, reduce downtime and ensure normal production and stability. Equipment for a long time operation or due to improper operation, some of the equipment will appear in the aggregate and affect the normal operation, at this time to stop working to clean. For the cleaning of the aggregate in the drying tower, the cleaning door should be opened, the hopper-shaped bottom aggregate should be removed with a long broom, and the discharge valve should be opened, and the tower should be rinsed with tap water. Cyclone separator in the dust collection, the same need to open the cyclone separator, broom cleaning aggregates, when necessary, also need water rinse. For the bag filter cleaning, should open the control switch, continuous tapping, then open the cleaning door, banging bag filter, and finally replace the bag. For slurry pipeline system cleaning, should open the two-way filter of the sewage valve, cleaning filter strainer and pipeline, and then open the material pump, water substitute, clean the pump tube, voltage regulator package and pipeline. After a period of time (generally around 600h) of the operation, the spray granulation dryer to carry out the necessary inspection and maintenance. For the feeding system, you should check the filter, piping, valves, nozzles, and so on to see if there is no clogging, timed cleaning, check the nozzle wear conditions in order to replace timely. Should check whether the pump oil leakage, suppression is normal, oil level is normal and so on. For fans, you should check whether the shaft and bearing oil is not hot, vibration, noise, etc., when necessary to clean the wind vane and to do balance proofing. For heaters, should check whether the heat pipe is normal, if necessary, clean the tubing, oil pump, nozzle three filter network.

In addition, should pay attention to the motor has no heat, vibration, abnormal sound, such as the control cabinet instrument and electrical work is normal. In addition, the equipment operation around 2 400h (generally while the production period), the maintenance personnel to the equipment for local disintegration and maintenance.