PRAGA is a full equipped gasification plant based on a 200 kWth updraft gasifier which was installed in June 2010 to test the co-gasification of biomass and sorted (plastic) MSW. The nominal input of the gasifier is 20-30 kg/h of feed with a maximum plastic content of 15%.
The plant is operated slightly above atmospheric conditions and it uses a mix air/steam as gasification medium introduced under a moving grate at the bottom of the gasifier. The produced gas (roughly 80 Nm3/h) moves upward from the bottom of the gasifier while the biomass particles travels downwards progressively trough zones of drying, pyrolysis, reduction and combustion.
The gas cleaning section is composed by a biodiesel scrubber and two coalescer filters in series. By organic scrubbing, most of the organic and inorganic compounds (tars, HCl, etc.) are removed from the gas, while in the coalescer filters the oil drag particles would be removed. This unit also allows a temperature reduction of the syngas coming out from the gasifier (about 300-400 °C). After the cleaning the gas is destined to a flare or to a hydrogen enrichment section. The facility is unique since is equipped of several solid, liquid (tar) and gas sampling probes/lines to fully characterise the process, moreover it is extensively automated and remotely controlled with in field flow-meters, pressure and temperature measurements along the gasifier and the clean-up line for on-line monitoring. Dedicated gas chromatographic analysis (off-line) have been assessed for gas quality and minor species characterisation while online devices based on FTIR have been planned and will be available for the BRISK service time. Tar are sampled after scrubber and coalescer filters for the off-line analysis, both ponderal and fine determination by GC-MS. The installation allows evaluating the process efficiency, the gasifier performance and the gas composition of the plant varying of feedstock specifications, RDF/biomass ratio and gasification medium. A major route to enhance the gasifier flexibility is the use of oxygen enriched air as gasifying agent. The experimental work is routinely coupled with modelling studies of the gasification process to estimate the effect of the main operating conditions and provide a theoretical basis for experimental results interpretation and evaluation (ChemCad, GaBi). An exhaustive chemical and physical determination of feedstock and product streams will be included with the granted Access, as well the online recorded measurements. More details can be found in literature, e.g. Energy Fuels 2014, 28, 3948−3956).