Design of a marabou torrefaction plant for energy purposes

Abstract

The use of forest residues as an energy source is a strategy used by developed and developing countries, mainly due to the decrease of fossil fuel reserves. The integration of torrefaction and pelletisation is one of the most promising routes for energy densification of lignocellulosic biomass. Dichrostachys Cinerea (Marabou) is classified as an invasive plant that affects large extention of arable land and because of its characteristics can be considered as a renewable source of energy. In the present work the objective is to design economically and evaluate a plant for marabou torrefaction for energy purposes. The flows related to the unit processes of the proposed technological scheme are quantified through mass and energy balances, as well as determining the main design parameters of the equipment for each of the stages of the process. The results of the economic evaluation show that the investment is feasible from the economic point of view, with a unit gain of 0, 04 $/kg validated by the dynamic indicators and the Discounted Payback Period of 3,20 years. A sensitivity analysis of different parameters is performed, indicating that the selling price of torrefied pellets have the greatest influence on the Net Present Value ($ 4,94E + 07).