How to increase capacity and improve whisky consistency by replacing flat sheet filtration

Creating a Superior Whisky

Whisky is distilled from a mash of fermented grains, including barley, corn, rye and/or wheat. Whisky producers apply expert and proprietary techniques for the creation of their unique brands. Particle removal and haze filtration are indispensable steps in production, common but essential to achieving quality specifications.

Historically, sheet filter presses are used in these applications. With the excellent capability to achieve depth filtration and adsorption, filter sheets are an ideal solution for turbidity reduction and haze removal in distilled spirits. However, sheet filters in a press configuration pose several challenges:

• labor-intensive handling and filter change-out
• high hold-up volumes which negatively affect yield on product changes
• drip losses resulting in lower yields or the need for reprocessing.

Additional drawbacks are large footprint, and relatively high capital investment. Finally, sheet filters are open systems. This can result in volatile organic compounds escaping to the surrounding environment and must often be exhausted via area ventilation systems, to avoid air quality and safety concerns.

Pall’s SUPRApak technology has a proven track record in brown spirits production. Its primary application with demonstrated benefits is in the replacement of traditional flat filter sheets for particle and/or haze removal, resulting in quality improvement, capacity expansion, and cost of ownership reduction.

The Solution

SUPRApak technology is a closed system alternative to sheet filtration for distilled spirits production. Due to their unique edge flow technology, SUPRApak SH modules achieve a better filtration effect than a similar grade of filter sheets. They remove components responsible for particulate and colloidal haze formation with minimal color adsorption. The result is a visually clear product, which meets producers’ organoleptic profile requirements.

During a full-scale trial at the distillery, SUPRApak performed as expected. It took one SUPRApak SH7200LW module less than half the surface area of the 19.7 m2 sheet filter assembly to process a batch of 30,283 liters (8000 gallons). Besides a substantially higher throughput, the SUPRApak solution consistently surpassed the filtrate quality specification after just a single pass through the module, achieving 0.4 NTU without a negative impact on color. Trial results demonstrated the optimum sizing for purposes of specifying a production-sized installation.

Single-pass filtration and relatively infrequent change-outs are achieved by conservative sizing. Continuous operation keeps the cost per filtered volume low and minimizes product losses. Several batches run consecutively without modules needing to be replaced. After installation of new, unused modules, fluid is recirculated for 5 minutes to ensure uniform saturation. Inconsistencies in color no longer pose a problem and the need for blending has been eliminated.

Each manufacturing cell is sized to handle 50% higher flow than the previous sheet filter installation. Together the 3 manufacturing cells process 3 different batches concurrently in 4 hours, whereas previously it took an average of 8 hours to complete one batch. In effect, capacity has increased by 6 times. The footprint in each cell requires about 66% of the space required by the sheet filter.

^{SUPRApak SH module and housing}