Energy integration of solar assisted Multiple Stage Evaporator and optimum parameter selection

Abstract

To reduce the conventional energy utilization in the pulp and paper mill, exploitation of renewable energy may provide a significant energy saving mostly in energy intensive subunits such as Multiple Stage Evaporator (MSE). MSE is used to concentrate the weak black liquor, a reach source of bio energy. Hence, this work explores the performance analysis of MSE with various proposed Energy Reduction Schemes (ERSs): Thermo-Vapor Compressor, Steam Split, Feed Split, Feed Preheater, and Flash Tanks. This analysis has been intended to develop the steady-state nonlinear energy models for proposed ERSs integrated MSE that translated it into a single objective unconstraint nonlinear optimization problem. Further, different optimization approaches (nonlinear programing and metaheuristics) have been employed to search the optimum process parameters and hence, maximize the energy efficiency. Moreover, to utilize the waste heat of condensate, feed, and product, flash tanks have been integrated with MSE which further improves the energy efficiency by 3.9% and 83% than that of base case model. Finally, the LFR solar field has been integrated to reduce the load of conventional energy utilization and ensures the self-sustainability of the paper mill by supplying the required amount of heat (3,399 kW) for the proposed hybrid MSE configuration.