Originally published in the August 2021 issue of Pulp-Paper World
Nuts and bolts
Removing the gearbox from the equipment set-up and replacing its functions with a modern, fit-for-purpose alternative coupled directly to the paper machine has proven to be practical and efficient. A gearbox suffers from energy losses during mechanical movements, which means higher energy consumption. When the drive is directly attached to the production machine using the permanent magnet technology, energy consumption is reduced.
The main advantage of this direct drive access is that it is gearless. When there are no gears, the motor speeds are lower. This way, a much longer service life can also be expected from the bearings. In ABB motors these last up to 200,000 hours or approximately 23 years in operation. The system is reliable right from the start and remains this way throughout its lifecycle, reducing electricity consumption and reaching high horsepower at low voltage.
Due to the permanent magnet motor, stator current is not needed for rotor magnetization, which further increases energy efficiency. This system has energy savings of around five percent compared to conventional induction motors. This is significant when the lifecycle of 20-30 years is also considered.
The permanent magnet technology combined with ABB's patented direct torque adjustment (DTC) mean it is possible to achieve high torque at low speeds. The specific energy efficiency achieved and the wide range of torques separate ABB's direct-use solution from those of other manufacturers. ABB's solution includes motors with over 50,000 Nm of torque.
AC-powered permanent magnet motors have proven high performance over a wide speed range of approximately 200-600 rpm. Reliability is simply increased by the fact that they have fewer moving parts. Moreover, ABB's patented DTC solutions do not require any pulse sensors for precise speed control, which improves reliability.
Several advantages have been identified from seeing direct drive systems in action, including energy efficiency, precise torque control, reliability, safety and security, lower engineering costs and reduced maintenance.
A clear vision of the future
ABB launched direct drives more than 20 years ago, with energy efficiency essential. Today, direct access technology still provides an excellent opportunity for forest industry operators to improve productivity and achieve significant energy savings.
Digitalization of the system uses advanced analytics and ABB’s proprietary data analytics tools. These are available via an operator-friendly interface and dashboards, and customers can receive industry-proven expert support and advice from ABB.
Overall, safety, security and maintenance risks can all be lowered through the use of direct drives and associated digital solutions. With fewer components configurations are straightforward and installations easier, with the floor area of the factory also more efficiently used. There are also fewer consumable parts which also reduces requirements for spare parts stocks. As mechanical gears and pulse sensors are not required, this reduces the amount of equipment and space needed. Subsequently, this means lower installation and commissioning times.
ABB's direct drives design focuses on energy efficiency and an economical set-up, which creates value for customers. The system fulfils all necessary functions while minimizing energy losses and enabling cost-effectiveness throughout the system's lifecycle.
