Yeast production aided through energy efficient rotary screw blowers

Its production site in Felixstowe produces bakers’ and distillers’ fresh cream and compressed yeasts, as well as instant dry yeast for supply to European and world-wide markets.

The success of the company’s 22-hour fermentation process cycle, which has fluctuating pressure and flow requirements, is totally reliant upon a continuous supply of oil-free low pressure air to deliver oxygen to the stock yeast. If the air flow to the fermentation vessel is interrupted, the entire product batch fails and has to be discarded, with consequent production loss and financial penalties.

It was this critical issue that prompted Lallemand GB’s management to consider replacing some of its conventional lobe type blowers, which were experiencing reliability issues, with 100% oil-free Class 0 certified rotary screw blower technology from Atlas Copco.

In seeking a solution, and comparing the merits of replacements, the company’s management was initially divided. According to Mick Arnold, Fermentation Manager at Lallemand GB:“On one hand there was an inclination to adopt updated versions of equipment that was familiar to us. However, we came to the realisation that there was no point in continuing to rectify problems with existing machines by virtue of add-ons, or risk the offer of new but hitherto untested hybrid solutions whose performance and efficiency are not yet established. On balance, our conclusion was that we should focus on sourcing proven, reliable and fully integrated replacements that took account of whole lifecycle energy costs, as well as demonstrating the potential to improve our productivity.”

This decision was endorsed by the company’s Engineering Manager, Roger Houghton: “We wanted reliable equipment that would be easy to install and capable of functioning straight from the box, and were impressed with the build quality, inherent reliability and integrated design of Atlas Copco’s ZS rotary screw blower offering.”

As a result, an Atlas Copco ZS200+FS-1200 oil-free, positive displacement rotary screw blower was installed on site, as a supplementary unit to the company’s conventional lobe type blowers, to evaluate its reliability and energy efficiency. Twelve months of trouble-free performance convinced Lallemand GB to install a complete blower installation, comprising three fixed-speed ZS 200+FS-1200 machines and a further three variable speed ZS200+VSD-1200 blowers to supply air at pressures between 0.199 and 1.16bar(g) to three of its six fermentation units.

The final endorsement of the new installation was voiced by Roger Houghton: “We have found that the Atlas Copco units cope with the essential fluctuations in process air demand, and it seems that screw blower technology can operate from 100% capacity down to 25% with very little change in specific power requirement. We estimate that our energy costs are down by at least 25% and at this rate we expect to achieve payback in less than three years.”

Technically advanced screw technology is at the heart of Atlas Copco’s ZS+ blowers close-tolerance screw elements that incorporate years of experience and innovation to deliver 100% pulsation-free and oil-free air that complies with ISO 8573-1 Class 0 (2010) certification. What’s more,an integrated gearbox means better transmission of power from the motor to the compression elements. There is no requirement for belt and pulley replacement, and the concept is designed for reduced maintenance costs and increased uptime.