Submitted to: Journal of Powder Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2014
Publication Date: 12/19/2014
Publication URL: http://handle.nal.usda.gov/10113/60595
Citation: Funk, P.A. 2014. Reducing cyclone pressure drop with evasés. Journal of Powder Technology. 272:276-281.
Interpretive Summary: Dust cyclones are an emissions control and product separation technology prevalent throughout agriculture and industry. The energy required to operate them may be reduced by adding a device that gradually slows down the air leaving the cyclone. This device, called an evasé, would not alter the particulate collection performance of the cyclone, but it might save energy otherwise lost in turbulence formed at the exit. In the U.S. cotton ginning industry there are collectively over 10,000 air streams using one or more cyclones; the potential energy savings may exceed 1.5 million dollars annually.
Technical Abstract: Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection efficiency. Three rectangular evasés and a radial evasé with a variable opening, were tested on two cyclones. Pressure drop was recorded for inlet velocities from about 10 to 20 m s-1. The radial evasé reduced cyclone pressure drop by between 8.7 and 11.9 percent when its exit area was equal to the flow area of the cyclone vortex finder or gas exit. A simple payback based on avoided energy costs was estimated to be between 3600 and 5000 hours, not including installation cost.