Circor International (Burlington, Mass.) announced that it recently provided three NTT 250-400 thermal oil pumps with variable frequency drive (VFD) for use on a medical glove production line in Yingke, China.
Installed in the heat-transfer system, the pumps control the temperature while the gloves dry in their molds. At an operating temperature of 280°C and almost atmospheric inlet pressure, the application requires a flow rate of 900 square meters per hour (m3/h) at 55 meters head. The NTT pump’s compact design enables it to operate at 1800 revolutions per minute (rpm), which is necessary to achieve the required flow rate, according to Circor.
NTT pumps are specially designed for thermal oil applications, meaning they can handle high temperature and avoid thermal expansion problems during heat-up and cool-down phases. The mechanical seals are designed to avoid hot oil spills during normal operation or in the event of seal failures. Circor adds high-temperature anti-friction bearings to enable low-maintenance operation.
To control the pump speed, the company includes a VFD to provide the electrical power at the required frequency to the 4-pole induction-motor. The frequency converter also enables a soft start of the motor without the high current peaks typically experienced with direct on-line (DOL) pump starts. The frequency converter allows speed and performance adjustments for process control, which will enable a sensible temperature control of the heat transfer system. Modern VFD use may also result in overall energy savings, typically 10% or more, according to Circor.