In 1862, the United Kingdom Kyu Bell invented a centrifugal fan, the impeller, housings for the round, brick casing, wooden straight after the impeller blades, efficiency was only about 40%, mainly used in mine ventilation.
In 1880, designed for mine drainage air volute casing, and backward curved blade centrifugal fans, structure has been improved.
1892 France cross flow fan developed in 1898, Ireland who designed Siro offset with forward blades centrifugal fans, and is widely used by States in 19th century, axial fans have been applied to mine ventilation and metallurgy blast, but the pressure of only 100~300 PA efficiency is only 15~25%, until the after in the 1940 of the 20th century was a faster development.
Fans often regulate the flow according to the host loads are needed. Currently, stone processing enterprises energy saving of fan adjustment method is relatively old, generally use the throttle. When throttle is used, air flow using the flow adjustment valve or throttle plate to adjust, amount of throttling fans, more than 50% even during low load throttling, due to loss and deviation from the efficient operation, energy is very serious. And if you adjust the fan speed, which can cancel the throttling loss and ensure the fan is always running at high efficiency, so you can significantly save power. Can be said to regulate the speed of the fan to run the blower is an effective way of energy-saving, new trends in industrial production reflects the current building materials.