Bonfiglioli drives sugar mill

Electrical switching & drive systems & components

3rd Quarter 2011 Electrical switching & drive systems & components

Alcoholera De Zapopan’s integrated process starts in the cane fields.The raw material, sugar cane, is converted to a variety of downstream end products including sugar and ethanol for alcoholic beverages, fuel and industrial applications. Other by-products of the solid residues are paper, pellets for use in domestic stoves and organic fertiliser for agricultural use. In addition, thermal and electric energy are produced for in-house use and for export. All these are produced from a renewable resource.

After the sugar cane has been mashed to extract the juice, the cane mills dry the resulting bagasse to between 48% and 50% humidity. The bagasse must be as dry as possible in order to optimise the efficiency of the thermal and electric energy generation process. The new mills have the capacity to process 100 tons of cane per hour. The other preparation and extraction machines are sized to handle this high level of production. The boiler burns the bagasse to produce steam which is sent to the distillation, cane diffuser and concentration equipment. Part of the steam drives a turbine that produces 8 MW of electric energy. Some is used on the plant and the balance is exported to the Mexican government’s Federal Electricity Commission.

The critical requirements of the client are punctuality (startup has to be completed before the cane harvest); ability to service the entire range of installed gearmotors; product reliability; and simple and compact gearbox architecture with the highest possible torque rating.

Bonfiglioli gearboxes are installed in most equipment on the plant, from canefields to distillery. These include agricultural machines; conveyors for cane feeding; roller conveyors for cane preparation; devices to chop and shred the cane; mills to extract the juice and dry the bagasse; belt conveyors for residues and ash; and sugar crystalliser mixer drives. There are two cane mills, each with four cane rolls. Each mill is driven by a Bonfiglioli gearbox connected by a torque limiter to a 306 kW electric motor with 1190 rpm rated speed, vector controlled by a frequency inverter.

In September 2010, Bonfiglioli delivered on time two 306 kW foot-mounted reducers for the two mills. Special features included a torque limiter on the input shaft; a special first planetary stage for high speed; a squared output shaft to be coupled with a special elastic joint on output; a water/oil heat exchanger with double filter to avoid downtime for filter change; an integrated lubricant pump driven by a Bonfiglioli AC motor; thermostats; and an oil pressure electro-valve.

This full planetary solution is the most compact and cost effective architecture for high torque reducers. For a mill with 306 kW of installed motor power at n1=1190 rpm, bearing life time greater than 36 000 h, and unlimited life of gears at full motor power, the maximum peak torque is 1,2 MNm.

Reliability, credibility and infield service keep the relationship going.

For more information contact Robert Rohman, Bonfiglioli, +27 (0) 11 608 2030, [email protected], www.bonfiglioli.co.za

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Electrical switching & drive systems & components

Bonfiglioli drives sugar mill

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