The sweet spot: how drives and motors can optimise sugar production and increase energy efficiency

The global sugar industry, which relies heavily on sugarcane and sugar beet as its primary raw materials, faces numerous challenges, such as aging infrastructure, change in climate, rising energy costs, and pressures from worldwide sustainability standards.

Addressing these issues, the implementation of variable speed drives (VSD), also known as variable frequency drives (VFDs) or, simply, drives, can revolutionise sugar plants, particularly those grappling with the intensive harvest cycles typical of tropical regions. Drives represent a significant advance in process control and quality, energy conservation, and operational efficiency.

Drives adjust motor speeds to align with exact processing needs, drastically cutting energy usage and aiding in managing fluctuating power demands. By moving away from mechanical controls like valves and gearboxes and installing high-efficiency motor-drive packages, sugar production plants will experience improved reliability, lower maintenance demands, and reduced downtime.

Using drives throughout sugar production

Improving operational efficiency in sugar production encompasses enhancing productivity, sustainability, and safety across all stages. The preparatory stages of sugar production — particularly for sugarcane milling and sugar beet slicing — are amongst the top candidates for energy efficiency gains with drives. Sugar beet slicing machines, for example, require precise speed control to ensure that the process is as energy efficient as possible. This process control also helps to avoid potential jamming and to improve overall reliability.

In the preparation and shredding phase, sugar beets are cut and shredded, requiring accurate motor speed and torque control to improve process flow. The motors must also be resilient to high mechanical forces.

In beet extraction, thin beet cossettes are treated with hot water to extract sugar, which calls for exact control over water flow and mixer speeds. Fast throughput and delivery are critical to optimal sugar extraction from raw products to get the maximum volume of the desired sugar quality produced.

For cane milling, heavy rollers are needed to extract the sugar amidst a dusty and potentially explosive environment, demanding precise motor control for uninterrupted operation without the risk of motors overheating. During clarification, lime milk adjusts the juice’s pH and removes impurities, necessitating accurate pH and flow controls. Byproducts like bagasse and molasses are often repurposed for energy generation or ethanol production, which means that the sugar industry can simultaneously reduce waste and contribute to sustainable practices by creating valuable secondary products.

The evaporation and crystallisation stages require varied torque and closed-loop control for fluid handling.

High-speed centrifuges separate the sugar crystals from the molasses, demanding precise speed control to ensure optimal crystal purity and quality. The final stage involves packaging the sugar, a step that takes place in an environment prone to dust explosions, requiring high-speed packaging lines that must operate in sync for safety and efficiency.

Utilising drives and high-efficiency motors throughout these processes can yield substantial energy savings and heightened reliability. Depending on the application, drives adjust the motor’s speed to match specific tasks, leading to energy reductions of between 20–60%. Operators can reduce energy consumption even more by combining drives with the latest IE4 or IE5 efficiency class motors. With the current rise in energy prices, the investment often pays for itself within a year or even less, taking into consideration that any improvement in the plant’s efficiency leads to a higher amount of energy that can be sold to the electricity grid.

Similarly, drives can boost energy efficiency in pumps used throughout the various sugar production processes to transfer water and juice. This advantage is crucial, considering that these pumps can account for a significant portion of a plant’s total energy consumption. The application of drives in pump control streamlines liquid flow, contrasted with traditional valve-regulated systems that incur substantial energy waste. Reducing a pump’s motor speed by just 20% can result in a more than 50% saving in energy consumption.

High efficiency in harsh, energy-intensive conditions

Another of the most compelling applications of drive technology lies in controlling sugar centrifuges. Centrifuges require a high starting torque for efficient operation and the capacity to withstand intense mechanical forces without faltering. They demand exceptional reliability, as consistent performance is crucial for their function.

These devices, which run several acceleration and deceleration cycles within an hour, benefit from regenerative drives such as ACS880 industrial drives; these special drives capture the energy that is usually lost when the machine slows down, returning it to the power supply network where it can be used by other equipment. A plant’s centrifuges can be balanced to smooth power demand, resulting in energy savings of up to 30%. Moreover, changing equipment operated at constant speeds to utilise variable speed technology to meet varying production volumes saves both time and money.

In the harsh environments of sugar production, which often include extreme heat, humidity, and high quantities of dust, the reliability and safety of drives and motors are paramount. ATEX-certified motors are specifically designed to prevent ignition and withstand explosions in hazardous environments containing highly combustible materials such as sugar dust, ensuring safe and uninterrupted operation. Additionally, high-protection class drives ensure reliable operation under harsh ambient temperature conditions.

The digital advantage

The sugar industry’s move toward digitalisation and advanced automation, using technologies like programmable logical controllers (PLCs), digitally connected drives, and motors equipped with smart sensors, is proving to be essential for optimising production processes. Digitalisation enables new, smart, and secure ways to prevent unexpected downtime, while optimising the operation and maintenance of assets to reduce the total cost of ownership.

For example, sensors can be added to make extensive condition monitoring possible, which means that plant operators can keep a close eye on the system’s health, predicting potential issues and preventing unexpected breakdowns before they occur. PLCs can also be used to automate processes involving pumps, drives, and sensors, leveraging scalable and robust components connected to the cloud. The PLC system also offers the benefit of integrating smoothly with current control systems, maintaining high availability under harsh conditions while supporting efficient sugar production.

Digital solutions can quickly and accurately gather plant data, unlike slower and often less precise manual methods. These solutions allow for the collection of a wide variety of data about manufacturing processes, taken directly from variable speed drives, motor sensors, and other PLCs.

Moreover, open fieldbus systems enable seamless integration of drives with any PLC or similar control equipment within sugar production facilities. This connectivity provides deeper insights and better management over the sugar manufacturing process, enhancing production control, and reducing the likelihood of equipment outage which could lead to significant losses, especially during the harvest season.

Towards a green transition

The sugar industry has historically demonstrated self-sufficiency, with byproducts like bagasse and molasses generating additional revenue through energy and ethanol production. The technological advances and digitalisation discussed will be influential in propelling the industry to the forefront of the green transition.

Simultaneously, by using drives, motors, and PLCs to further enhance energy efficiency and reliability, these improvements will steer the industry towards a more sustainable and profitable future.

Here you cane find out more.

Grigory Abramov, Global Food and Beverage Segment Manager, ABB Drives

Grigory Abramov10.06.2024