Written By Christian Pettit (Flottweg)

A decanter centrifuge is an easy and efficient way to recover product that’s usually lost in yeast and hops sludge. The operating principle is simple: a slurry is fed into the horizontal bowl and accelerated to a high speed. Solids are forced onto the walls and liquids are discharged under pressure through the impeller. Inside the bowl, a turning scroll scrapes the solids off the walls and conveys them through the cone-shaped end of the bowl where additional moisture is squeezed out. Solids are then discharged and collected.

The centrifuge isn’t used to process the entire fermentation tank. Only the bo

ttom 10-20 percent of the tank needs to be processed and when no more solids are detected in the feed, the rest of the beer is sent forward to filtration/clarification and then on to packaging.

The machine is sized appropriately to the typical volume of sludge in the tanks. Often, this means the machine is small relative to the total volume of the tank since only a small portion of the contents are processed. A smaller centrifuge is cost effective and uses less energy.

Recovered beer is expelled from the machine under pressure and goes directly back into tank via the racking arm or standpipe.

Here’s an example of what may be achieved with a decanter centrifuge:

• 440-barrel batch
• 3 pounds of hops per bbl
• 10 percent product loss (44 barrels)
• Processing sludge that contains 50 percent solids by volume yields 22 additional barrels of product to sell per batch

Prioritizing Quality and Safety

Success depends on creating a high-quality, consistent product that tastes great and meets strict food safety requirements. Centrifuges can help.

Clean in place (CIP) and stainless-steel hygienic equipment set up is standard for beverage applications. A decanter centrifuge can easily be integrated with the existing CIP system or used as a stand-alone. The bowl, scroll, and all inlet and output lines and meters are thoroughly cleaned to avoid mixing batches or introducing bacteria.

Recovering saleable beer efficiently is a great reason to add a decanter centrifuge to the cellar, but there are several additional advantages, including:

• Cutting fees and surcharges for wastewater by removing the maximum amount of solids.
• Saving labor costs associated with batch process presses or filter baskets. A centrifuge is fully automated and integrates seamlessly with most system’s so it’s simple to monitor and most adjustments are computer controlled on the fly.
• Reducing wear and tear on downstream equipment including the clarifier.
• Minimizing solids disposal costs by increasing dryness levels (i.e. less weight and volume to haul). Dried spent brewer’s yeast can also be recovered and sold as a dietary supplement.

A decanter centrifuge offers Craft Beer Professionals a clean, efficient way to get the most product out of every batch.

Christian Pettit is the sales manager for Brewing, Distilled Spirits and Wine for Flottweg Separation Technology Inc., located in Independence, KY. Christian has a background in CNC machining as well as electrical/mechanical maintenance and process development. He holds a mechanical engineering degree and has over 15 years of centrifuge experience, including stints in the service department, process engineering and sales.