Heat recovery with steam compressor: Dynamic model of a superheated steam drying system to evaluate efficient system operation
The pulp and paper industry continually seeks innovative technologies to enhance efficiency, reduce energy consumption, and improve product quality. Superheated steam drying (SSD) is a promising alternative to conventional drying methods, offering significant advantages in terms of energy efficiency, environmental sustainability, and product quality. In this contribution, a dynamic model of an SSD system is presented that enables the latent heat recovery at higher temperatures and pressure levels, by using a steam compressor. The steam compressor utilizes the excess steam mass flow from the dryer, upgrading the recirculating superheated steam atmosphere again to target dryer inlet conditions. However, the integration of SSD technology with existing paper manufacturing processes can be complex and may require substantial modifications to the production line. The innovative nature of SSD necessitates a thorough understanding of its operation to ensure successful implementation. To address these challenges, a dynamic model simulating the transient behaviour of the paper machine and auxiliary equipment has been developed. This model provides insights into the energy consumption and performance by simulating the interactions between the main process units (dryer, steam compressor) and auxiliary equipment (heat exchanger, electrical heating). The dynamic model considers the impacts of temperature levels and air in the steam atmosphere. The functionality of the model is shown through selected scenarios and the impact on the efficient operation of the system is analysed. The dynamic model presented in this study offers a valuable tool for achieving an efficient system design and operating conditions for SSD technology.