June 2, 2015
Switzerland is known for its chocolate, watches and snow-capped mountains. The country’s sole sugar producer has plans to sweeten that list.
Situated in the swiss cities of Aarberg and Frauenfeld, sugar producer Zuckerfabriken Aarberg und Frauenfeld (ZAF) makes more than 250 000 tonnes of sugar every year; an amount that would fill a train spanning nearly four times the 175 kilometers between the two cities.
At the heart of the process is an Atlas Copco single stage vapor compressor that’s been running for almost 30 years. The machine is vital to the Aarberg plant’s operation of turning sugar beets into white sugar.
“The entire factory wouldn’t work without the mechanical vapor compressor,” Plant Manager Thomas Frankenfeld says.
The main sugar-producing season runs from September to Christmas. Over the course of the season, farmers from all over Switzerland deliver about 10 000 tonnes of sugar beets a day on their tractors or trucks, and then the sugar-making process can begin.
First, the beets are washed and sliced open. The evaporator removes water from the beet until a sugar concentration of about 65% is achieved. More water is removed as the resulting syrup goes through a crystallizer, and sugar crystals slowly start to form. The crystals are then dissolved, filtered, and recrystallized until white sugar emerges.
Things haven’t always worked this smoothly. Around 2000, ZAF faced a major challenge due to significant gaps in sugar prices in different regions of the world. Brazil, which then could produce sugar very cheaply, controlled the international market price. To combat this problem, ZAF moved to streamline its production processes.
Facing the pressure at the time, we improved our operations,” Frankenfeld says.”
The Aarberg plant has cut its energy consumption by 30% in the past decade, and it now uses less energy than any other sugar factory in the world. It achieved this status in large part by using waste heat to drive the production of crystallized sugar.
“We have developed ways to constantly reuse thermal energy,” Frankenfeld says. “To us, waste heat is everything below 40 degrees Celsius.”
The process requires less steam than comparable procedures, and that boosts efficiency. But because steam also acts as a provider of energy in the process, the Aarberg facility uses too little of it to supply enough power to produce syrup (which eventually becomes sugar) at the desired concentration. That’s where Atlas Copco’s vapor compressor comes in.
The machine increases the pressure and the temperature of the steam in the system, which can then serve as the heating medium for the liquid being formed by the existing vapor. That liquid, once cooled, turns into crystallized sugar.
“The low need for fuel consumption is directly related to the function of the mechanical vapor compressor,” Frankenfeld says.
After the season is over, the rest of the year is dedicated to maintenance. That includes the Atlas Copco compressor, which undergoes regularly scheduled preventive maintenance checks by Atlas Copco engineers.
Maintenance of the machine is very important to ensure overall efficiency and reliability,” Frankenfeld says.”
He calls the vapor compressor a “triple-A machine.” It has been running since 1985, and its roar will resound at the Aarberg plant again as soon as September rolls around.
“Maintenance of the machine is very important to ensure overall efficiency and reliability.” Thomas Frankenfeld, Plant Manager