• Energy Research

Qualitative and quantitative measurements of tar from poultry litter gasification in an air-blown fluidised bed.

Torrefaction is suggested to be an effective method to improve the fuel properties of biomass and gasification of torrefied biomass should provide a higher quality product gas than that from unprocessed biomass. In this study, both raw and torrefied Miscanthus × giganteus (M×G) were gasified in an air-blown bubbling fluidized bed (BFB) gasifier using olivine as the bed material. The effects of equivalence ratio (ER) (0.18-0.32) and bed temperature (660-850°C) on the gasification performance were investigated. The results obtained suggest the optimum gasification conditions for the torrefied M × G are ER 0.21 and 800°C. The product gas from these process conditions had a higher heating value (HHV) of 6.70 MJ/m(3), gas yield 2m(3)/kg biomass (H2 8.6%, CO 16.4% and CH4 4.4%) and cold gas efficiency 62.7%. The comparison between raw and torrefied M × G indicates that the torrefied M × G is more suitable BFB gasification.

Low temperature gasification of poultry litter (PL) was experimentally studied in a lab scale fluidized bed reactor. The experiments were carried out at three different equivalence ratios (ER) of 0.17; 0.21; 0.25 and temperature 700 °C, to investigate its impact on cold gas efficiency (CGE), carbon conversion efficiency (CCE), gas yield, lower calorific value (LCV), and tar evolution. Maximum CGE and LCV of the produced gas was 43.4% and 3.34 MJ/m3 respectively at an ER of 0.25. The maximum CCE of 72% was attained at the highest value of ER (0.25). The gas yield showed an increasing trend with ER reaching its highest value of ~1 m3/kgdaf N2 free. Highest amount of total tar was 2.41 g/Nm3 in the dry gas at the lowest tested ER. Styrene- xylene, phenol, and naphthalene, were the components with the highest concentrations of up to 30%, whilst the tar compounds detected but couldn’t be identified ranged between 25-30% with respect to the total tar yield. The average compositions of the main components in permanent gases (vol %, dry basis) at the indicative value of the lowest ER were as follows: H2:7.87%, CH4:2.04%, CO: 6.37%, CO2:11.47%, C2H4:1%, and C2H6:0.22.

Gasification of Miscanthus x giganteus (MxG) was conducted in an air-blown bubbling fluidized bed (BFB) gasifier using magnesite as bed material and a moderate rate of biomass throughput (246.82–155.77 kg/m2h). The effect of equivalence ratio (ER) (0.234–0.372) and bed temperature (645–726 °C) on the performance of gasification was investigated. The results reveal that MxG is a promising candidate for energy production via BFB gasification; of the conditions tested, the optimal ER and temperature are approximately 0.262 and 645 °C, where no sign of agglomeration was found. The product gas from this condition has a higher heating value of 6.27 MJ/m3, a gas yield of 1.65 N m3/kgbiomass (39.5% of CO and 18.25% of H2 on N2 free basis), a carbon conversion efficiency of 94.81% and a hot gasification efficiency of 78.76%. Agglomeration was observed at some higher temperature conditions and believed to be initiated by the formation of fuel-ash derived low melting temperature K-rich (potassium) silicates (amorpho...

European regulations require that by 2030 waste suitable for recycling, material recovery, or energy recovery will no longer be allowed to end up in landfills. Material composition in non-recyclable MSW bins dictates which valorization measures could be implemented. This study examines 32 non-recyclable MSW bins in the Getafe municipality (Spain). The bulk non-recyclable MSW bin is separated into 15 residue materials along with non-combustible materials. Merely 18.1 % of the non-recyclable MSW bins occupy non-recyclable waste. This indicates inadequate separation at source. MSW samples are grouped into six clusters with similar properties using the K-nearest neighbor methodology. Representative sample from each cluster is pyrolyzed at 520 ◦C. The main product of pyrolysis is liquid, which makes up 57.9 wt%, while solid and gas fractions are 16.4 and 16.5 wt%, respectively. Liquid fraction is a blend of aromatic, aliphatic, oxygenated, and nitrogenated compounds, while CO2 is the main gas compound.

The use of a binary mixture of solar molten salts (60 wt% NaNO3 and 40 wt% KNO3) as a heat transfer medium for the production of a solar fuel by the thermochemical conversion of biomass is investigated in the present paper. Thermochemical conversion can be a route for converting the surplus solar irradiation via the direct contact of nitrate molten salts and biomass into storable chemical fuel. Traditional fixed-bed pyrolysis and molten salts pyrolysis have been carried out under an inert atmosphere at a temperature of 500 degrees C. The composition of the permanent gases and the bio-oil produced has been analyzed along with the temperature profiles inside the reactor. Two distinctive pathways have been observed: an endothermic process in the case of traditional fixed-bed pyrolysis and an exothermic process in the case of molten salt pyrolysis. An attempt has been made to identify possible causes for such differences. The financial support of the Spanish Ministry of Economy and Competitiveness from project ENE2014-54942-R is gratefully acknowledged by the authors.

Sepiolite, a clay mineral that is commonly used as adsorbent, is proposed as bed material for biomass gasification in a lab-scale bubbling fluidized bed. In order to compare the obtained gas composition and tar generation, silica sand has been used as reference bed material. C cardunculus L. has been employed as biomass feedstock. The operating temperature is varied from 830 to 875 degrees C, at constant equivalence ratio (ER) of 0.30. The gas produced with sepiolite as bed material has a slightly lower quality than the gas generated with silica sand, the lower heating value (LHV) is 0.4-1.4 MJ/Nm(3) lower for sepiolite than for silica sand. However, the tar generation is rather reduced in the sepiolite bed and the tar composition is also different among the bed materials: the polycyclic aromatic hydrocarbons fraction (PAH) is drastically reduced while oxygenated compounds arise in the sepiolite tests. Sepiolite properties such as surface area and morphology have been analysed by means of specific surface area (BET) and scanning electron microscopy (SEM-EDS) before and after the experiments. The fuel behaviour and the properties of sepiolite induce the adsorption of tars and molten ashes on the sepiolite surface, leading to a much better performance in terms of tar mitigation and agglomeration. The authors would like to express their gratitude to the financial support of the Spanish Ministry of Economy and Competitiveness from project ENE2014-54942-R. Alen Horvat acknowledges COST funding (short term scientific mission-STSM) under a COST STSM Reference Number: COST-STSM-FP1306-34300, supporting his exchange stay at University Carlos III of Madrid.