Sunshine Sugar wins 2013 PACE Zenith Award for Food & Beverage

PACE Zenith Awards 2013: Food & Beverage Category

WINNER: Sunshine Sugar
Project: Centrifugal drive system saves energy at Sunshine Sugar mill

Sunshine Sugar needed to replace their ageing centrifugal drive system, and chose a Siemens AC drive-motor combination, which yielded 40 percent savings in energy consumption. The project was completed on time and within budget.

The original centrifugal drive system was a 298KW DC unit. When Siemens proposed replacing it with a 184 kW AC motor-drive combination, Siemens was challenged with proving the solution.

Siemens drew on their 1,200 reference sites worldwide of successful centrifugals operated by AC drives. They also provided detailed analysis on their success with reducing the size of motors and drives by controlling the switching rate of the Insulated Gate Bipolar Transistor (IGBT).

Siemens also sent in a global expert on drives from their Sugar Competence Centre in Germany to ensure Sunshine Sugar had all the technical information and insight into the solution to make its decision.

Sunshine Sugar was won over to the solution by the support offered by Siemens. In particular, the technicians at the company were drawn by the Active Front End technology, which is a standard feature in Siemens SINAMICS drive systems.

This feature of the 184 kW drive system allows a reduction of the size of the motor and drive without losing power, achieve harmonics of less than 1 percent and consequently significantly reducing energy costs.

The Active Front End feature also provides a number of other benefits, such as an exceptional dynamic response and self-commutated converters with IGBTs and clean power filter in the input. It effectively combats main system resonance due to harmonics, neutralising the effect on mains voltage.

The system eliminates the need for compensation and filter circuits, with an overall power factor of cos phi = 1, due to sinusoidal currents and voltages with no mains-typical harmonics and so absolute minimum mains pollution on the line side.

There is also no conduction-through with fuse tripping in response to mains under voltage or failure in generator mode thanks to active tripping, making the implementation especially suitable for weak or unstable systems.

The voltage step-up mode provided by the system compensates for mains under voltages. Commutating voltage dips means no mains voltage. While previous approaches recommended DC drives for centrifugals, today’s technology and approaches now utilise AC drives as the preferred drivers for centrifugal applications.

The largest centrifugals available can handle 2,000 kilograms of massecuite in a single charge. Variable-speed AC drive systems are normally used for the centrifugals because they require very little maintenance. They are robust, long-lasting, can operate continuously throughout a campaign and offer much better reliability than the variable-speed DC drives.

Martin Sinclair (L) Associate Publisher, PACE, congratulates winner Brian Jackson of Sunshine Sugar.

Martin Sinclair (L) Associate Publisher, PACE, congratulates winner Brian Jackson of Sunshine Sugar.

Sunshine Sugar installed the SINAMICS AC drive and motor solution, commissioned and optimised locally by Siemens. Siemens also provided an I/O to interface to the existing Bailey DCS system for bi-directional communication.

Since commissioning, Sunshine Sugar has achieved a substantial (over 40 percent) saving in power consumption. Power recordings have confirmed a reduction from 1.7 down to 1.0 kWh/tonne of massecuite despite this reduction being recorded prior to optimising the drive. Sunshine Sugar is undertaking further analysis to determine the final energy savings.

Due to the success of this solution, Sunshine Sugar have placed a second order with Siemens to upgrade the drive and motor of a second fugal.

The NSW Sugar Milling Co-operative was formed when cane growers purchased the three NSW sugar mills from CSR in 1978. The mills are located at Condong on the Tweed River, Broadwater on the Richmond River and Harwood on the Clarence River.

The Co-operative also operates a sugar refinery which is located alongside the Harwood Mill. This is owned by a joint venture company, Manildra Harwood Sugars, in which the Co-operative is a 50 percent partner with Manildra Flours.

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