Simulation of tar reduction alternatives in the coffee stems gasification process

This work developed a simulation model able to compare three different secondary methods of tar retention that assess the energy consumption, investments and tar concentration of each alternative to clean the syngas produced in the gasification of coffee stems. The alternatives were the installation of a car filter (FC), a heat exchanger (IC) and activated carbon filtering media (FCA). The experiments were carried out in the Power Pallet GEK 20 kW downstream Gasifier and runs of 3, 6, 9, 12 and 24 hours of operation. The tar concentration was measured via VOC's direct detection equipment and showed values of 23, 18.7, y 222.3ppm for IC, FC and FCA respectively. Estimation errors obtained for the model developed in Aspen Plus® software for tar concentration were 16.75%, 14.63% and 0.02% for normal operation, FC and IC respectively. An Economic evaluation reported a value of 0.43, 4.06, 0.45 and 4.09$/kw produced for normal operation, FC, IC and FCA respectively. Finally, the analysis of the internal combustion engine thermal efficiency exposed that IC and FC potentially increase the total energy production in 440kwh per year compared to normal operation.