Estudo de caso: aplicação de um controle de energia específica em refinadores a disco

Abstract

The present paper approaches the case study in the WestRock Pulp and Paper Factory, more specifically the process of preparing the cellulosic pulp, so that the paper to be produced can be formed, making sure the quality standards required by the market. In this sense, are discussed the process and control of the refining intensity of the fibers, main aspects of the dough preparation. The refiners used in the factory are disc ones, and the refining intensity control is performed by closing or opening the distance between the discs from the refiner in order to increase or decrease the printed impacts of the fibers. Previously the approach control of the disks was carried out manually by the operator, based on some laboratory tests. In this study, we propose the evaluation of the results of implementation of an automated refining control, in order to understand the gains and improvements provided by it. The implemented control uses the refining potency, flow and cellulose consistency data to perform a approximation control of the refiner discs, based on a setpoint defined by the operator. In this case, the operator continues to determine the required refining levels, but the automatic control prevents that its potency increases considerably, when a greater amount of dough enters the refiners, providing an excess of refining and a very high energy consumption that is unnecessary. The reverse process is also controlled, preventing refiners from refining the fibers sparingly because of a drop in the dough flow through them. Considering this refining control, the cellulosic pulp is refined in a more homogeneous way, preventing the fibers from losing important characteristics during paper formation. Finally, the data obtained through actual measurements of the machine in operation are evaluated. The paper shows the improvements provided by the refining using the energy control, both in terms of quality and energy savings, as well as increased production and, consequently, the company's profitability. The conclusion of the study demonstrates that the refining control is directly related to the quality of the paper and its production. In addition, by reducing the energy consumption of refiners, papermaking becomes less expensive and, as a result, the company becomes more competitive in the market.