Title: Renewable integration and energy reduction in multiple stage evaporator

Abstract

Multiple Stage Evaporator (MSE) is an imperative part of the pulp and paper industry. It is used to process the waste byproduct named Black Liquor (BL) to enhance its solid concentration that may be further utilized to produce biomass based energy. This process accounts very high energy consumption which leads to energy intensiveness of this unit. A substantial amount of energy saving can be achieved by integrating different Energy Reduction Schemes (ERSs) with the MSE. Steam split, feed split, feed preheater, thermo-vapor compressor, etc. are the well-known ERSs that can be incorporated with the MSE to reduce the energy utilization. Hence, this study investigates the hybrid ERSs integrated MSE model to observe its energy efficiency in optimal manner. The prime focus of this work is to maximize the energy efficiency of the MSE unit in teams of maximum steam efficiency which is computed by developing nonlinear mathematical models, obtained by employing the first law of thermodynamics. To achieve the maximized energy efficiency, an optimization function has been developed under constraint environment and solved by using metaheuristic based approach named Flow Direction Algorithm. Another, ERSs named flash tanks can also be integrated with this system to encourage the waste heat re-utilization and ensures an increase in energy efficiency with constant steam consumption. This work also deals with the incorporation of the Linear Fresnel Reflector with ERSs integrated MSE which is capable of reducing the conventional energy load. The overall integrated MSE model achieves an energy efficient and renewably operated MSE unit that may enhance the self-sustainability of the industry.