Centrifugal Stillage Separation

Posted by Jim Ling on 7/20/20 2:05 PM

8-feathers-Distillery-proucts_600x4488 Feathers Distillery explains how Kason Corporation treats their waste stream to eliminate sewage surcharges, decrease solid waste disposal fees and to provide a “free” food source for local livestock to nearby farmers in an article published across the globe in Filtration + Separation, Industrial Water World, Brewer & Distiller International, and other publications. Using locally sourced grains and water from a nearby artesian well, the distillery was founded in 2004 to produce spirits.

Separation Evaluation – Solving for Efficiencies

8 Feathers could not lauter because their hammer mill grinding process produces fine grains that clogged the filter media. In searching for solutions, filter presses, screw presses and chemical flocculation were investigated and ruled out. The Kason Centri-Sifter proved to be the most cost-effective choice, occupied a small footprint, minimized maintenance, and offered simple cleaning options.

8 Feathers provided a 10-gallon (38-litre) sample of stillage for testing which was conducted on both circular vibratory and centrifugal screeners. In the footprint desired, the vibratory separator could not produce output as dry as the Centri-Sifter or at nearly as high a rate. The 50 gpm (189 l/min) desired with capacity to spare. 8 Feathers Distillery was encouraged by the test run when the sifter processed a sample of 1500-gallons (5678-litres) and pushed 40 GPM (151 l/min) without performance degradation. 8 Feathers purchased a Kason model ‘MO-SS’ Centri-Sifter with a 140 mesh (105 micron) heavy duty reinforced stainless steel screen to provide effective separation and minimize the risk of screen blinding.

Processing over 3000 lbs of grain weekly while distilling, 8 Feathers produced more than 7500 lbs of stillage waste as a by-product. Discharge to the municipal wastewater treatment system requires liquid which is free of solids and within an acceptable pH range to avoid increased sewage surcharges.

To minimize sewer surcharges cost, 8 Feathers needed a solution that would allow them to successfully separate spent grain from the liquid without contaminating solids while neutralizing the liquid waste discharged.

Installing the Sifter

8-feathers-Distillery-Centrifugal-Sifter-side_600x400Once installed, 8 Feathers was to sustainably and economically, dispose of its grain slurry waste by separating the grain from water using a centrifugal sifter and could donate grain to local farmers as livestock feed. The aggressive screening action of the centri-sifter removes liquids to minimize both sewer surcharges and transportation costs associated with the waste while providing a “free” food source to local farmers.

The Centri-Sifter was Installed 8.5 ft (2.6 m) above the plant floor, directly over the vat that receives the water. The unit measures 21 in (533 mm) wide, 33 in (832 mm) tall and 75 in (1899 mm) long, including its 3 hp (2.2 kW) motor.

8-feathers-Distillery-Centrifugal-Sifter-door-open_600x639

The Separation Process

  • The liquid/grain mixture is fed into the centrifugal sifter
  • The liquid is acidic and therefore must have a pH level closer to water
  • The watery/grain mixture passes into the horizontal screen cylinder. Auger and rotating paddles propel the mixture against the screen, this accelerates the passage of liquid through the screen
  • The liquid then passes through a vat and is treated with ash to reduce the pH level before flowing into the public water system
  • Grain solids unable to pass through screen are funneled into a tote

The centrifugal sifter’s end cover plate can be easily hinged opened, allowing tool-free removal of the screen cylinder and paddle assembly from the cantilevered shaft for cleaning. The operators simply backwash the sifter with water, cleaning the pipes and the screens at the same time. This cleaning process only took 8 Feathers two or three minutes.

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Topics: Centrifrugal Sifters, Distillery & Brewery, Case Histories