On the stick

Illustration | Bosch Rexroth AG
Marginal Column

The John Lewis Company, a Canadian manufacturer of the sticks used in ice cream bars, cuts energy consumption by 70 percent in one process step thanks to variable-speed pump drives.

 

A seal of bio-fresh quality, a certificate of origin, a squeaky-clean public image. To an ever increasing extent the world’s food processing industry is responding to consumer expectations to savor edible treats with a clear, green conscience. But sustainability in regard to the ingredients and the packaging is no longer sufficient. Growing attention is being paid to environment-friendly production, as well. This is also true for ice cream, a market with enormous potential.

A large part of these wooden sticks is supplied by the peeling plant at John Lewis Industries, located in the Canadian province of Quebec. Here more than 26 million ice cream sticks roll off the belt every day. Ever since 1920 this company has supplied leading ice cream makers all around the world with sticks made of birch, a wood that lends no taste of its own. The company draws upon sustainable forestry certified by the Forest Stewardship Council (FSC). But this supplier also wants to keep energy con­sumption during production as low as possible.

Sustainable forestry, eco-friendly production

That is why the firm launched an optimization project for the production process. The company consulted with energy efficiency specialists from Bosch Rexroth to take a hard, close look at the power unit for the hydraulically driven axes at the wood receiving station. There an automatic lift device raises the trunks and moves them into the peeling mill. If there are any disruptions in feeding, the crane – which is powered by the same hydraulic unit – frees up the jammed trunks and sends them on to the production line. To ensure that the operator could always respond quickly and flexibly to carry out this procedure, which is initiated manually, a constant-displacement pump continuously ran at full power in the past. The flow that was not needed was returned to the tank. At partial load that unit drew 12 kilowatts in this operating mode and at peak loads up to 20 kilowatts.

Savings: 70 percent

In their efforts to improve this unsatisfactory efficiency level, the specialists at Rexroth turned to the Sytronix SvP7000, a variable­speed pump drive. Its intelligent IndraDrive controls lower the rotation speed during idling phases or when operating at partial load, delivering just the amount of flow actually called for by the crane operator. This conversion brought about instant success. When running at partial load the hydraulic power unit now uses just two kilowatts – a 70 percent energy saving. The conversion itself was fairly easy and uncomplicated. Pre­defined functions and open interfaces for command level communications simplify integration, even into pre-existing systems. Users need not carry out any extensive programming. They need only assign parameters to the predefined regulators.

And it’s quieter, too

Energy is one factor but an acceptable working environment for the employees is just as important. “We are not talking just about energy savings, but also about considerable noise reduction and better system response,” explains Stéphane Pronovost, project manager at John Lewis Industries and responsible for rebuilding the system. That’s because the Sytronix reduces, on the one hand, average noise emissions by up to 20 decibels – without any additional noise abatement measures. In addition, regulation following demand also improves operator control. With the highly dynamic matching to real consumption, the integrated regulators compensate for the peculiarities of fluid technology so skillfully that the operator need not undertake any adjustments. What’s more, the crane now responds more sensitively and is more productive.

Standard for the future

In addition, Sytronix reduces the amount of cooling required since the hydraulic fluid heats up less than in the past. This both extends the service life of the hydraulic fluid and further reduces energy requirements. “I hope that this technology will become the industry standard for all hydraulic power units in the future,” Pronovost stressed. John Lewis Industries is making its contribution and is even now examining the feasibility of converting an­other power plant.