Mid Sweden University

In this work, the biomass property is evaluated based on pyrolysis behavior of biomass fuels by means of TGA and online gas analysis. Wood, sawdust, pine bark, peat, straw, black liquor and microalgae are chosen as the biomass feedstocks for the pyrolysis study. The measurement results show high volatile content for algae and black liquor (around 85%) and low volatile content for pine bark and peat (around 69%). Differently from woody biomass, the DTG curve of straw has a single dominant peak at much lower temperature, which suggests a dominant component of hemicellulose in biomass, while algae and peat have a broader temperature specturm of devolatilization but much lower peak temperature. CO2 is released first and H2 later in the pyrolysis process for all biomass feedstocks, whileas the peak of CO formation follows CO2 formation trend for most feedstocks used, except for peat and pine bark which give a peak later at high temperature. This indicates secondary reactions of tar cracking, steam reforming and char gasification.

Fuel availability and flexibility are important issues for biomass-based heat/power and advanced biofuel plants. The physical and chemical properties of biomass feedstocks vary from one to others to a great degree, which must be taken care of for the reactor design/operation, system optimization and blend feedstock application. In this work, the biomass property is evaluated based on pyrolysis behavior of biomass fuels by means of TGA and online gas analysis. Wood, pine bark, peat, straw, black liquor and microalgae are chosen as the biomass feedstocks for the pyrolysis study. The measurement results show high volatile content for algae and black liquor (around 85%) and low volatile content for pine bark and peat (around 69%). Differently from woody biomass, the DTG curve of straw has a single dominant peak at much lower temperature, which suggests a dominant component of hemicellulose in biomass, while algae and peat have a broader temperature specturm of devolatilization but much lower peak temperature. CO2 is released first and H2 later in the pyrolysis process for all biomass feedstocks, whileas the peak of CO formation follows CO2 formation trend for most feedstocks used, except for peat and pine bark which give a peak later at high temperature. This indicates secondary reactions of tar cracking, steam reforming and char gasification.

An internal reformer is developed for in situ catalyticreforming of tar and methane (CH4) in allothermal gasifiers.The study has been performed in the 150 kW dual fluidised bed (DFB) biomass gasifier at Mid Sweden University(MIUN). The MIUN gasifier is built for research onsynthetic fuel production. Reduction of tars and CH4 (exceptfor methanation application) in the syngas is a major challengefor commercialization of biomass fluidised-bed gasificationtechnology towards automotive fuel production. The MIUN gasifier has a unique design with an internal reformer, where intensive contact of gas and catalytic solids improves the reforming reactions. This paper presents an initial study on the internal reformer operated with and without Ni-catalytic pellets, by evaluation of the syngas composition and tar/CH4 content. A novel application of Ni-catalyst in DFB gasifiers is proposed and studied in this work. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases down to 5 g/m3 and the CH4 content down below 6 % in the syngas. The tar content can be decreased further to lower levels, with increased gas contact to the specific surface area of the catalyst and increased catalyst surface-to-volume ratio. The new design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas quality.

An internal reformer is developed for in-situ catalytic reforming of tar and methane (CH4) in allothermal gasifiers. The study has been performed in the 150 kW dual fluidised bed (DFB) biomass gasifier at Mid Sweden University (MIUN). The MIUN gasifier is built for research on synthetic fuel production. Reduction of tars and CH₄ (except for methanation application) in the syngas is a major challenge for commercialization of biomass fluidised-bed gasification technology towards automotive fuel production. The MIUN gasifier has a unique design with an internal reformer, where intensive contact of gas and catalytic solids improves the reforming reactions. This paper presents a study on the internal reformer operated with and without Ni-catalytic pellets, by evaluation of the syngas composition and tar/CH₄ content. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H₂ content together with lower CH₄ and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases down to 5 g/m³ and the CH₄ content down below 6% in the syngas. The novel design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas quality