Syngas production at pilot scale from the residue of lignocellulosic based biorefinery

About one third of the eedstock is recovered as solid after conversion of the carbohydrates, at current operation of biorefinery which are fed with lignocellulosics. The residue contains mostly lignin and has to be exploited in order to close the cycle and recover from it the energy to produce steam and power required to run the biorefinery.  The updraft gasification is a process characterized by high thermal efficiency and operational simplicity that make it interesting for treating the wet residues of biorefinery, such those producing 2G ethanol.

The plant that was used in this work is a 20-30 kg/h facility made up of an updraft gasifier, gas cleaning and gas upgrading sections to achieve high concentration of H₂. The gas cleaning section is composed by a biodiesel scrubber for tar removal and by two coalescing filters in series to remove the aerosol entrained by the gas. This configuration is very effective to reduce the harmful effect of contaminants on the catalysts that are used to upgrade the gas in the downstream section. The gasification tests were performed with fermentation residues from reed and straw and using a steam/air mix as a gasification medium. During the tests, all the main operating parameters, such as process flow rates, temperature profile through the reactor, temperature and pressure control throughout the downstream piping, were continuously acquired and processed by a DCS. Energy efficiencies, mass balances and gas quality obtained at different equivalence and steam to biomass ratios were discussed.