Co-gasification of waste tire and pine bark in CO2 atmosphere is reported at different blend fractions of waste tire (WT) and pine bark (PB) in the range of WT:PB = 0:1, 1:0, 1:1, 1:3, and 3:1 with a focus on syngas production. The results are reported along with the thermal decomposition behavior of the blends investigated using thermogravimetric analyzer (TGA) in Ar atmosphere. Characteristics of syngas from the gasification of blends were conducted using a fixed-bed reactor in CO2 atmosphere at 800 and 900 degrees C. Gasification behavior was examined with focus on evolved flow rate of H-2, CO, total hydrocarbons (CmHn), and total syngas yield at the two temperatures for different blend ratios. CO2 consumption under the gasification conditions was evaluated. Gas yield efficiency and energy recovered in gasification were also calculated and compared. Synergistic effects in the syngas yield and the role of waste tire and pine bark were analyzed by a direct comparison of the results on experimental yields from WT-PB blends as compared to the correspondingly calculated aggregate results from the gasification of separate feedstock components at 800 degrees C and 900 degrees C. Results showed that increase in pine bark ratio increased peak flow-rate of H2, CO, total syngas, but decreased peak flow-rate of CmHn at the two temperatures. The syngas yield of gases at 900 degrees C were higher than that at 800 degrees C for a given blend ratio. The peak value of temporal CO2 consumption coincided with the peaks of CO yield for all the feedstocks except for pure waste tire at 800 degrees C and 900 degrees C. Gas yield efficiency of gasification at 800 degrees C reduced using blends, while no obvious influence was found at 900 degrees C. Increase in pine bark decreased the energy output both at 800 degrees C and 900 degrees C. These results provide an insight into energy recovery and waste treatment potential for both waste tire and forestry waste as well as CO2 utilization in the thermochemical conversion.

This study examines the acid and alkaline treatment of pine wood to help understand the effect of alkali and alkaline earth metals (AAEMs) content on the pyrolysis behavior at different temperatures. Acid and alkali pretreatment of pine wood were conducted to modify AAEMs content by ion-exchanging method. Thermal kinetic behavior of the pretreated samples was first conducted by a thermogravimetric analyzer (TGA) at different heating rates that provided activation energies of pyrolysis. Gas formation behavior of the samples for different extents of conversion was carried out in a fixed-bed reactor at two different temperatures of 823 K and 1073 K. Evolutionary behavior of the gas components during pyrolysis, including flow rate, and yield and their energy content were measured and compared. Results showed that the values of activation energies increased with the extent of conversion for all the pretreated samples examined. The effect of AAEMs on pyrolysis behavior of biomass varied with the extent of conversion. The presence of AAEMs in biomass decreased the decomposition energy at low conversion while it greatly improved under high conversion. Besides, alkali treated sample with higher AAEM content enhanced the gas and char yield while it reduced the bio-oil production at low temperature with low conversion. However, at high temperature the opposite trend was observed. Presence of AAEMs was favorable for the generation of H-2, CO, CO2 and CnHm at low temperature, while it showed an inhibition effect on CO and CnHm yield and syngas energy at high temperature. The catalytic mechanism of AAEMs on the pyrolysis behavior at different temperatures was discussed based on activation energy and gaseous formation. Results revealed decomposition of carboxylate at low temperature and formation of stable biomass-Na (BM-Na) structure at high temperature that led to the variation of activation energy and changed gaseous products yield and syngas energy. Acid washing pretreatment was found to be effective to enhance bio-oil yield at low temperature and increase syngas energy at high temperature. Syngas yield of acid pretreated sample was 19.6% higher than that raw sample, while alkali pretreatment was favorable for enhanced char yield. These results help to achieve the desired yield of gas or solid using AAEM modification.

In this study, we conducted life cycle assessments (LCAs) for fuels based on different types of agricultural residues and determined the characteristics common to all LCAs. Each fuel type required specific conversion technology during the feedstock stage, particularly during the production and collection processes. We divided the field-to-fuel life cycle into five high-level and relatively independent sub-stages: production of agricultural residues, collection of agricultural residues, conversion of agricultural residues to biofuels, biofuel distribution, and biofuel utilization. We then illustrated the common characteristics during the feedstock stage for the first two field-to-fuel life cycle sub-stages: production and collection of agricultural residues. Agricultural residues-to-grain weight and price ratios and multifactorial LCA allocations were summarized for the production stage. In addition, the energy use availability coefficient, collection radius, and emissions were determined for each fuel type during the collection stage. System boundaries and benefits of direct emissions reduction during the feedstock stage were also discussed. Our results provide guidance for future LCA studies on agricultural residue-based biofuels.

The role of dual location fuel injection (versus single injection) is examined for improved mixture preparation with enhanced reaction distribution in the combustor that offers reduced emissions. A cylindrical combustor was used at a combustion intensity of 36 MW/m(3) atm and heat load of 6.25 kW. Three different configurations were examined for the effect of dual location fuel injection using methane as the fuel. NO reduction of 48% was achieved with fuel injected at two locations versus single location at an overall equivalence ratio of 0.7. The OH* Chemiluminescence intensity distribution with dual location fuel injection showed the reaction zone to shift further downstream that provided longer fuel mixture preparation time prior to ignition under favorable fuel distribution conditions. The longer mixing time helped to improve mixture preparation with lower emissions. The NO* chemiluminescence signatures supported the results obtained on reduced NO emission. Mean to maximum OH* signal showed that dual location fuel injection enhanced distributed reaction at certain fuel distributions between the two locations (fuel injection ratio lower than 70%) for all the three configurations examined. Increase in air injection velocity from 46 m/s to 102 m/s showed up to 85% NO reduction utilizing dual location fuel injection without any increase in CO emission. Increase in air preheats from 300 K to 600 K reduced the extent of NO reduction. Dual location fuel injection provided improved reaction zone distribution in the combustor for all the experimental conditions reported here. Correlations are provided that describes the NOx emission as function of fuel injection ratio. (C) 2016 Elsevier Ltd. All rights reserved.

The role of catalyst (Ni/Al2O3) position on improved gasification of polypropylene (PP) in CO2 atmosphere using a fixed bed reactor at 900 degrees C was examined and the results compared with non-catalytic gasification. The catalytic gasification included in-situ and quasi-in-situ (with feedstock located close to but not directly in contact with the catalyst) configuration. Results are reported on the evolutionary behavior and yield of carbon monoxide (CO), hydrogen (H-2), hydrocarbons (CmHn) and total syngas. Compared to non-catalytic gasification, in-situ, and quasi-in-situ catalytic gasification produced higher H-2 by 120.5% and 137.1%, higher CO by 38.2% and 24.0%, higher CmHn by 57.1% and 98.2%, and higher total syngas by 44.1% and 43.8%, respectively. CO2-assisted gasification of PP with Ni/Al2O3 catalyst significantly enhanced the gases evolution rate and improved the syngas yield. Results revealed better catalytic activity with quasi-in-situ configuration in the thermal decomposition of PP into H-2 and CmHn than in-situ catalytic configuration. However, in-situ catalytic configuration provided more CO under similar gasification conditions. Approximately 0.8, 1.1 and 1.0 kg of CO2 could be consumed per kg of PP feedstock to generate syngas energy yield of 27.5, 43.1 and 48.1 MJ with non-catalytic, in-situ and quasi-in-situ catalytic configuration, respectively, suggesting efficient utilization of both CO2 and PP waste for clean and efficient energy production.

Swirlers are commonly used in gas turbine combustors as they provide recirculation zones and reduce axial velocity for enhanced flame stability. Swirl provides hot gas recirculation zone at front end of the combustor for enhanced mixing between hot reactive species and the freshly introduced mixture. In this paper, the impact of confinement on a swirl assisted combustion was investigated with focus on the flowfield under unconfined and confined conditions. The features of the flowfield were characterized under both isothermal and reacting conditions. Experimental results showed that for the unconfined cases, the flowfield exhibited the traditional central toroidal recirculation zone. Upon confinement, this zone shortened and also widened with increased velocity fluctuations across the combustor. Increase in the Reynolds number further enhanced the recirculation zone and increased the velocity magnitudes and turbulence. For reacting conditions, minimal recirculation was noticed for the unconfined flame. The recirculation zone was significantly enlarged upon confinement (compared to the non-reacting case) and with increase in Reynolds number. In general, the fluctuating velocity was found to be higher in the confined case compared to the unconfined case, and even higher at increased Reynolds number. (C) 2016 Elsevier Ltd. All rights reserved.