Sweet Crystals Integrated Sugar Mill (SCISM) in the Philippines tried to improve the productivity of its centrifuges by shortening the cycle time but this resulted in a number of problems.
Firstly, the centrifuges were fitted with two-speed motors which were started direct-on-line. During the starts high inrush currents were drawn from the mains. The reduced cycle times resulted in a peak power increase which put a severe load on the diesel alternator supplying the factory.
Secondly, the centrifuge speed changes were not properly carried out by the contractors and this caused frequent breakdowns.
Finally, during deceleration of the baskets extra energy was lost in motor heating.
SCISM turned to Parker SSD to find a solution. Parker SSD proposed an innovative solution based on its regenerative AC drives linked on a common DC bus. They were sequenced in a way which reduced the overall demand on the diesel alternator.
Parker SSD also offered technical assistance throughout the project, from the specification stage through to system design, generation of electrical drawings, cubicle testing, system commissioning and production ramp up.
The project was ready on the designated day and resulted in several benefits.
Energy saving
The energy from the spinning centrifuges was no longer wasted as heat in the braking resistors but was transferred to motoring centrifuges through a common DC link. The regenerative drives allowed the energy to be fed back to the mains when the machine was globally regenerating. This resulted in a reduction of about 25% in overall power consumption. On the batch centrifugal station alone the energy savings amounted to about 160 kWH per hour of operation.
Better reliability
The centrifuges were now smoothly controlled during the whole machine cycle. The frequent mechanical breakdowns completely disappeared. Uptime on the batch centrifuge increased significantly, resulting in an improvement in productivity.
Short payback period
With shorter machine downtime, better productivity and a dramatic reduction in energy consumption, it was calculated that the investment in the revamping would be recovered in less than 24 months. In fact SCISM enjoyed a payback period of 18 months through energy savings alone.
Higher productivity
Parker SSD drives can control precisely, accelerate and safely brake the inertia of the centrifuges throughout the cycle of operation.
The batch centrifuge cycle time was reduced by 20%, with the centrifuge cycles increasing from 20 to 24 per hour. The productivity improvement resulted in an additional sugar output of 4000 kg per hour which was achieved while consuming less energy.
Reduction of peak power
The innovative Parker SSD cascade control allowed the batch centrifuges to be sequenced, which dramatically minimised the peak power demand on the diesel generator.
For more information contact Hendrik Botha, EP Normand, +27 (0) 11 824 1320, [email protected], www.epnormand.co.za
| Tel: | +27 11 824 1320 |
| Email: | [email protected] |
| www: | www.epnormand.co.za |
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