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In a biomass gasification process, condensation of inorganic species can cause problems such as corrosion and deposition on the downstream equipment. In this work, in order to investigate the condensation of inorganics during the gas cooling step of the biomass gasification system, both experimental and modelling studies were conducted. Experiments were performed on a pilot-scale steam/oxygen blown fluidized bed gasification facility. A CO 2 cooled probe was located at the head of a filter to condense inorganic species. Five thermocouples were used to monitor the probe temperature profile. Deposits on the probe were characterized using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to analyze the elemental composition of deposits. A process model based on the local chemical and phase equilibriums was developed using software SimuSage to predict both release and condensation of inorganics. A customized thermodynamic database extracted from the FactSage 7.1 was used during model calculations. Two cases including with and without addition of bed material were calculated. Results show that the identified elemental compositions of deposit under different gas cooling temperatures reasonably agree with the elemental compositions predicted by model calculations. This demonstrates that the established model and the customized thermodynamic data are valid. A large amount of carbon is identified in the deposit of low temperature probe sections, which may come from the condensed tar. Additionally, a temperature window is found, where melts are formed during gas cooling. [ABSTRACT FROM AUTHOR]

The use of catalytic fast pyrolysis (CFP) of biomass to produce high-quality bio-oils as potential substitutes for conventional fuels plays an essential role in the decarbonization of the world. In this study, continuous CFP tests of sawdust using three commercial-ready catalysts were performed. The overall objective is to screen appropriate catalysts and catalyst loading amounts for further commercialization and upgrading by evaluating the quality of the organic fraction bio-oils and clarifying the relationship between the hydrogen-to-carbon atomic effective (H/C eff) ratio and bio-oil yield. The results displayed that, owing to a cracking effect of the catalyst, all catalytic cases had higher H/C eff ratios and larger relative area percentages of hydrocarbons determined by NMR. Thermogravimetric analysis reveals that, compared to non-catalytic bio-oils, catalytic bio-oils showed more distillates in the diesel range. Increasing the catalyst-loading amount also showed the same effect. Overall, all bio-oil products from catalytic cases had H/C eff ratios higher than 0.6, indicating the production of promising oil for hydrodeoxygenation. By analyzing and fitting the data from this work and comparing with the literature, it could be concluded that its yield would decrease as the bio-oil product quality increases (the H/C eff ratios increase). [Display omitted] • Continuous CFP tests were conducted, providing insight for scaling up. • Three different commercial-ready catalysts with two WHSV values were studied. • All catalysts-induced oil products with H/C eff higher than 0.6. • SA catalyst induced the most attractive oil production at WHSV of 0.5. • A negative correlation between H/C eff ratio and bio-oil yield was verified. [ABSTRACT FROM AUTHOR]

Pretreatment of biomass becomes more and more important due to the large scale application of biomass having low energy density. In this paper, steam exploded biomass pellets (Black pellets) and unpretreated biomass pellets (Gray pellets) were gasified with air and steam at an updraft HTAG (High Temperature Agent Gasification) unit. Decomposition characteristics of pellets were first analyzed with TGA (thermo gravimetric analysis). Early decomposition of hemicellulose and cellulose were seen with Black pellets around 241 °C and 367 °C respectively. Introducing CO2 led comparatively high mass loss rate with Black pellets. Gasification of Black pellets resulted in syngas with high CO and hydrocarbon contents while Gasification of Gray pellets resulted in high H2 content of syngas. LHV (lower heating value) of syngas was high around 7.3 MJ/Nm3 and 10.6 MJ/Nm3 with air gasification and steam gasification respectively. Even with significantly low syngas temperature with gasification of Black pellets, only slightly high total tar content was seen compared to that of Gray pellets gasification. Phenolic compounds dominated the tar composition. In general, steam gasification of Black pellets seems to be more feasible if syngas with high energy value is desired. If higher H2 yield is preferred, gasification of unpretreated pellets likely to be more attractive. [ABSTRACT FROM AUTHOR]

Gasification of excavated landfill waste is one of the promising options to improve the added-value chain during remediation of problematic old landfill sites. Steam gasification is considered as a favorable route to convert landfill waste into H 2 -rich syngas. Co-gasification of such a poor quality landfill waste with biochar or biomass would be beneficial to enhance the H 2 concentration in the syngas, as well as to improve the gasification performance. In this work, steam co-gasification of landfill waste with biochar or biomass was carried out in a lab-scale reactor. The effect of the fuel blending ratio was investigated by varying the auxiliary fuel content in the range of 15–35 wt%. Moreover, co-gasification tests were carried out at temperatures between 800 and 1000 °C. The results indicate that adding either biomass or biochar enhances the H 2 yield, where the latter accounts for the syngas with the highest H 2 concentration. At 800 °C, the addition of 35 wt% biochar can enhance the H 2 concentration from 38 to 54 vol%, and lowering the tar yield from 0.050 to 0.014 g/g-fuel-daf. No apparent synergetic effect was observed in the case of biomass co-gasification, which might cause by the high Si content of landfill waste. In contrast, the H 2 production increases non-linearly with the biochar share in the fuel, which indicates that a significant synergetic effect occurs during co-gasification due to the reforming of tar over biochar. Increasing the temperature of biochar co-gasification from 800 to 1000 °C elevates the H 2 concentration, but decreases the H 2 /CO ratio and increases the tar yield. Furthermore, the addition of biochar also enhances the gasification efficiency, as indicated by increased values of the energy yield ratio. • Steam co-gasification of landfill waste with biochar or biomass was carried out. • No clear synergetic effect was observed in the case of biomass co-gasification. • The addition of biochar promotes synergetic effects on the H 2 yield production. • Addition of biochar produces higher H 2 yield than that of biomass. [ABSTRACT FROM AUTHOR]