Reducing energy requirement for drying of beet-pulp: Simulation of energy integration between superheated steam and air drying systems
2017
Chryat, Yacine | Romdhana, Hedi | Esteban-Decloux, Martine
Beet-pulp dehydration in the sugar industry is a highly energy intensive unit operation. Producing 1 kg of dried beet-pulp requires ∼2–3 kg of water to be removed. The cost saving is a real challenge in sugar factory as the current dryers are underperforming (around 3 MJ/kg of water evaporated) because the heat recovery is limited and only a small proportion of dryer exhaust can be reused. The aim of this study was to investigate by simulation the energy efficiency of an independent multistage drying method that combines superheated steam drying (SHSD) and hot air drying (AD). Two case studies awarding the two types of energy coupling (AD then SHSD or SHSD then AD) are presented and compared. An approach of optimization is developed from energy balance. A number of operating parameters of the two drying configurations are investigated using sensitivity analysis. It proves that both cases allow an energy economy around 40% compared to the conventional dryer. Nevertheless, the SHSD-AD plant may present more benefits for a better quality product.
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