Gas conditioning in H2 rich syngas production by biomass steam gasification: Experimental comparison between three innovative ceramic filter candles

The biomass steam gasification is a promising path to obtain hydrogen-rich syngas and to improve the global efficiency for cogeneration purposes. The present study reports the results of a campaign of steamgasification tests performed in a bench-scale gasifier (0.1mID) housing in its freeboard a ceramic filter, in a temperature range of 800 Ce815 C. Three new ceramic filters have been tested: (i) noncatalytic candle with new support, (ii) filter candle with catalytic layer, (iii) filter candle with new integrated catalytic foam system and results were compared to those obtained in tests without candle. The volume composition of the syngas was monitored and analyzed by online measurement by means of infrared e thermal conductivity detector (IR-TCD) facilities to evaluate the CO, CO2, CH4, H2, NH3 composition. The Topping Atmosphere Residue (tar) content was evaluated by gas-chromatograph mass spectrometer (GCMS) facility; gas yield, water conversion and char conversion were also calculated from direct measurements. The best results were obtained in the case of innovative catalytic filter in association with cycled olivine bed, obtaining gas yield equal to 1.80 Nm3/kgdaf (vs 1.00 Nm3/kgdaf without candle); observed to theoretical water conversion ratio equal to 0.88 (vs 0.33); H2 volume content equal to 56% (vs 39%); total tar content equal to 0.14 g/Nm3 (vs 6 g/Nm3)

Clean syngas from biomass—process development and concept assessment

This paper summarises the long development work done at VTT for gas clean-up for various synthesis applications. The development work has covered the most challenging and costly steps in biomass gasification based processes: high-temperature gas filtration and reforming of hydrocarbon gases and tars. The tar content of product gas is one of the main factors defining the temperature window in which the hot-gas filter can be operated, which in the case of fluidized-bed gasification is at 350-500 °C. Research is ongoing to achieve higher and thus more economical operation temperatures. Optimal operation of a catalytic reformer can be achieved by using a staged reformer where zirconia-based catalysts are used as a pre-reformer layer before nickel and/or precious metal-based catalyst stages. The temperature of the reformer is optimally increased in subsequent stages from 600 up to 1,000 °C. According to the techno-economic analysis, increasing the hot-gas filtration temperature by 300 °C or methane conversion in the reformer from 55 to 95 % both lead to about 5 % reduction the liquid fuel production cos