Numerical Investigation of a Heat Pump Demonstrator for Partial Electrification of the Steam Supply for Paper Drying

Abstract

Industrial process heat is currently mostly generated by using fossil fuels. In order to reduce emissions, heat pumps have been identified as a key technology to electrify a wide range of industrial processes. For applications in the temperature range higher than 150°C there is a high demand for research and development with the aim of bringing technologies to market maturity. This is one of the main purposes of the EU-funded project SPIRIT (https://spirit-heat.eu/). As a part of this project, a novel mechanical vapor recompression (MVR) system is integrated into the steam network of a paper mill producing high pressured steam with temperatures up to 180°C. This paper presents transient simulation studies of the MVR system in preparation for safe commissioning. A detailed model is introduced considering volume dynamics and thermal inertia. The model is generated in Modelica using the TIL library with customized components. The focus of this work is the investigation of an operating strategy for start-up. From initial ambient conditions the system can be heated up rapidly to supply high pressure steam after a time span of 800 sec. Technical feasibility can be shown with stable operation during all phases of the proposed start-up procedure. The transient models will be further used to be tuned with experimental data in order to support secure operation and to perform set-point optimization for relevant operating conditions.