Optimizing Hopper Airflow and Temperature Controls in Plastic Processing
Hopper airflow rates of 0.8 to 1.2 m3/hr per kg/hr combined with a dew point below -40 C prevent hydrolytic degradation and guarantee uniform drying.
Static Pressure Drop
Meaning
Loss of air pressure that occurs as process air moves through a drying system, including filters, hoses, desiccant beds and the resin hopper. Static pressure drop is caused by friction and the resistance of the material to the airflow. It is a fundamental variable in sizing the blowers and fans required to maintain the necessary air volume for drying, as any restriction can significantly reduce the volume of air reaching the material in the vessel.
Airflow Resistance
Fine-grained resins or those with a high percentage of regrind dust create more resistance and increase the static pressure drop. If the pressure loss becomes too great, the air volume delivered to the hopper decreases. This reduction leads to uneven drying and potential moisture defects in the finished product.
System Health
Sudden increases in the value often point to a blocked filter or a compacted resin bed. Monitoring the static pressure drop across different components helps maintenance teams identify which part of the system is failing. A low reading might indicate a leak or a disconnected hose.
Operational Cost
High resistance requires more power from the blower motors to maintain the required flow rate. Optimizing the design of the ducting and the selection of the resin geometry can minimize the static pressure drop and lower the overall energy consumption of the facility.