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Sugar production with a rock-solid CBM motor

Sugar production with a rock-solid CBM motor
Marginal Column

July 2015


Hydraulic direct drives built by Rexroth form the basis for dependable operations at an Indonesian sugar mill – and by doing so they secure the livelihood of thousands of farmers.

Turning sugarcane into refined sugar is a demanding business: extremely sensitive to the weather and working under tough production conditions. This is also true for the Krebet Baru 1 sugar mill on the Indonesian island of Java. “The sugar season lasts from six to seven months a year. During this phase, our customers have to count on production around the clock – regardless of the amount of sugarcane delivered and the speed of the production line,” explains Tomas Kallin, Industry Sector Manager for Sugar at Bosch Rexroth.

In the past, the operator for Krebet Baru 1, the state-owned company PT Rajawali Nusantara Indonesia (RNI), has had challenges with failures of gearbox solutions. That is why the enterprise considered adopting drives for its sugarcane presses that were both reliable and adaptable. These units press and wash the cane while extracting the sugar in a five-stage process. The ambient conditions are a genuine challenge. Shock loads, high temperatures, and frequent spraying with water to remove dust are all a matter of everyday operations. What’s more, agricultural production is weather-dependent and if the plantations are wet Krebet Baru does not get any raw material. The sugar cane cannot be stored either since it spoils within 24 to 36 hours of harvesting. To maintain continuous production the speed of the mill is reduced so that it runs slower. The CBM will keep the torque ensuring a good extraction.

Continuous operation

RNI found the answer in a hydraulic drive system made by Rexroth. It comprises four Hägglunds CBM motors, the drive units, the control system and the piping. Even at lower speeds, the CBM generates high torque, achieving better extraction than before. At the same time, the compact motor design saves space and is easy on shafts and bearings whenever shock loads occur. “This direct-drive system has a wider range of operation with good results compared to traditional drives,” emphasizes Hari Widodo, Development and Technical Manager at RNI. What’s more, Bosch Rexroth can dispatch locally based service technicians to maintain the entire system.

Continuous operation is also indispensable because the bagasse – the waste product left after crushing the cane – is burned to generate steam. That steam drives an electric generator supplying the entire plant with power. Following any production stoppage, it is also necessary to restart the boiler associated with the generator. But it is not only RNI that profits from the drives’ reliability.

“The thousands of farmers who deliver the raw material depend on the sugar mill to be working on the day they bring their harvest in,” Tomas Kallin stresses. This is also true whenever system output has to be scaled up or down to suit the load. “The compact-design CBM motors save space and create a system that can easily be reconfigured to suit capacity requirements without having to halt production.”