18-26: Improvement of sugarcane cogeneration system: use of sugarcane straw for heat and power generation

The Brazilian sugar and alcohol mills represent a successful example of biorefinery, which integrate the production of sugar, ethanol and energy. Besides being considered an important green protection for the soil, straw has a high energy potential with approximately 1/3 of the energy available in the cane. Bearing this in mind, this work aims to evaluate the use of straw in the energy cogeneration system (CHP - Combined Heat and Power). A simulation platform for an integrated bioethanol process (first and second generation) and sugar production with cogeneration system was developed. The simulation was carried out with the aid of Aspen Plus^TM process simulation environment. In the simulation, two cogeneration systems were considered, one for the 1^st generation process and another for the integrated process (1^st and 2^nd generation). Both cogeneration systems were based on the Rankine cycle, where the heat produced in the boiler is used to generate process steam. The process steam is expanded in backpressure and condensing-extraction turbines to generate electricity and mechanics power to the plant. Different percentages of straw were used in the simulation in order to increase the amount of surplus bagasse for the second generation ethanol production process.