Resource efficient operation of an evaporator network in the viscose fiber production

摘要

The production of viscose fibers for textile and non-woven applications is performed by spinning dissolved cellulose xanthogenate into an acidic spin bath to regenerate the cellulose to viscose fibers. During the production process water accumulates and dilutes the spin bath. Therefore, water is removed continuously to ensure favorable reaction conditions and a high product quality. This is accomplished in the plant of the Lenzing AG, Austria, by using a large evaporator network that consists of several spin bath cycles and more than 20 evaporators. In order to optimize the operation of the network with respect to a minimum consumption of fresh steam for given production requirements, data-based models for the performance of the individual evaporators have been fitted to historic data and some parameters are adapted online. The optimiziation problem is a Mixed-Integer Nonliner Program (MINLP) with discrete decisions on the allocation of equipment, continuous decisions on the distribution of the load and a nonlinear model. The optimization is part of a decision support tool that is currently tested on the shop floor at Lenzing.