Energy Reductions in the Pulp-and-Paper Industry by Upgrading Conventional Pumping Systems through the Installation of VFDs – A Case Study

In this paper we intend to demonstrate the benefits that can be obtained by upgrading conventional pumping systems, i.e, without speed control, pervasive in the older project Pulp-and-Paper industries, through the installation of Variable Frequency Drives (VFDs). The main objective is to significantly reduce the energy consumption and associated cost, while simultaneously avoiding the production of excess Greenhouse Gases (GHGs), contributing to the global sustainability efforts. A case study is presented, where a conventional level control system, based on an automatic valve and a constant speed driven pump, is converted to a control strategy based on the combined actuation on the valve and on the speed of the pump. For this study, it is shown that a yearly energy reduction of about 60% is achieved. This reduction, associated with a 160 kW motor, results in a yearly energy reduction of about 533 MWh and an associated reduction of about 250 tonnes CO2. Negative effects in the power quality such as harmonics and common-mode currents must be considered, but could be kept under acceptable limits. With the results presented in this work, fully developed in an actual industrial environment, we aim to motivate those in the industry to pursue similar objectives.