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991.
In this study, an artificial neural network (ANN) model as a machine learning method has been employed to investigate the exergy value of syngas, where the hydrogen content in syngas reached maximum in bubbling fluidized bed gasifier which is developed in Aspen Plus® and validated from experimental data in literature. Levenberg-Marquardt algorithm has been used to train ANN model, where oxygen, hydrogen and carbon contents of sixteen different biomass, gasification temperature, steam and fuel flow rates were selected as input parameters of the model. Moreover, four different biomass samples, which hadn't been used in training and testing, have been used to create second validation. The hydrogen mole fraction of syngas was also evaluated at the different steam to fuel ratio and gasification temperature and the exergy value of syngas at the point where the hydrogen content in syngas reached maximum were estimated with low relative error value. 相似文献
992.
《International Journal of Hydrogen Energy》2021,46(65):32783-32799
A two-stage system involving alkaline thermal gasification of cellulose with Ca(OH)2 sorbent and catalytic reforming with Ni/Fe dual-functional CaO based catalysts is proposed and applied to enhance H2 production and in-situ CO2 capture. The results show that the H2 concentration is maximized at a considerably lower temperature (500 °C) than commercialized biomass gasification processes, reducing energy consumption. Sol-gel method is deemed better than impregnation method for its lower cost and higher-concentration H2 production. Among the prepared catalysts, sol-NiCa catalyst exhibits the best performance in CO2 absorption, resistance to carbon deposition, and cyclic stability, creating maximum H2 concentration (79.22 vol%), H2 yield (27.36 mmol g−1 cellulose), and H2 conversion (57.61%). Introduction of Ni rather than Fe on the CaO based catalyst promotes steam methane reforming at moderate temperature range of 400–600 °C, generating low contents of CH4 (5.38 vol%), CO2 (4.82 vol%), and CO (10.58 vol%). 相似文献
993.
Deepak Kumar Singh Jeewan V. Tirkey 《International Journal of Hydrogen Energy》2021,46(36):18816-18831
The present study developed a robust method for the modeling and optimization of variable air gasification parameters using the ASPEN Plus simulator and Response surface methodology (RSM). A comprehensive thermochemical equilibrium based model of downdraft gasifier was developed by minimizing Gibbs free energy. Model validation was done by comparing the simulated result with the experimental result of four different feedstocks from the literature and, a good agreement was attained. The Complete modeling of the air gasification process was segregated into four phases viz. biomass drying, biomass decomposition, biomass gasification, and producer gas filtration. Drying operation and yield distribution during pyrolysis were computed by incorporating FORTRAN sub-routine statement. Sensitivity analysis was performed to obtain syngas composition using Syzygium cumini biomass fuel and different gasification performances like gas yield (GY), cold gas efficiency (CGE), and higher heating value (HHV) using gasification temperature (600–900)0C and equivalence ratio (ER) (0.2–0.6). Furthermore, RSM has been employed for the multi-objective optimizations of the variable gasification parameter. Central composite design (CCD) is adopted. Two independent parameters viz. temperature and equivalence ratio have opted as decision parameters for estimating the optimum performance parameters i.e., hydrogen concentrations, CGE, and HHV. Regression models created from the ANOVA results are found to be highly accurate in predicting output response variables. The optimal values of H2, CGE, and HHV are found to be 0.1 (mole frac), 25.23%, and 3.96 MJ/kg respectively corresponding to optimized temperature at 887.879 °C and equivalence ratio 0.32 using response optimizer. The composite desirability observed was 0.59. 相似文献
994.
《International Journal of Hydrogen Energy》2021,46(6):4798-4807
In this study, lignin, one of the commonly occurring natural polymers, is extracted from banana agro-waste. Lignin is recovered from the spent liquor produced during alkaline pre-treatment of agro-waste and precipitated by acidification. This study focuses on the physio-chemical characterization and thermal degradation behaviour of lignin extracted from agro-waste biomass. The extracted lignin yield accounts for nearly 12% of the biomass composition. Spectral analysis, FTIR and NMR explain purity and carbon skeleton characteristics of herbaceous lignin monomers, majorly G and S units. Morphological analysis by SEM showed hollow spherical structures with large surface area for the extracted lignin. The calorific value of extracted lignin was experimentally found to be 21.4276 MJ/kg, which suggests the possible use of extracted lignin as an alternative to sub-bituminous coal. Thermal studies of lignin showed that lignin degrades in a wide temperature range releasing CO2, CH4, H2O, CO and H2. The volatile content of extracted lignin is found to be 31.42%, which suggests its possibility for gasification process. The overall outcome supported that recovered lignin from agro-waste is a potential resource for bioenergy. 相似文献
995.
《International Journal of Hydrogen Energy》2021,46(60):30926-30936
A series of LaNi1-xCoxO3 (x = 0, 0.2, 0.5, 0.8 and 1) perovskite catalysts were prepared successfully and applied for toluene steam reforming as a model tar molecule. The Ni–Co alloy formation in reduced LaNi1-xCoxO3 was confirmed by TPR, XRD and XPS. The strong interaction in LaNi0.8Co0.2O3 between Ni and Co produced highly dispersed and smaller metal (8–9 nm), higher reducibility and larger amounts of active sites as well as more abundant oxygen defects and higher surface/lattice oxygen mobility, confirmed by XRD, TEM, TPR, XPS and O2-TPD. Also, a higher electron density prevented Ni from oxidation and sintering; a more oxidized Co (Co3+) facilitated the dissociation of water and activation of CO2, thus removing the coke. At 600 °C, S/C = 3.4 and WHSV = 16.56 ml h−1 gcat−1, an equilibrium conversion was achieved initially and over 80% conversion after 24 h were obtained for LaNi0.8Co0.2O3 with a high H2 yield (81.8% at maximum) and 8.0 of H2/CO ratio. The graphitic/filamentous coke formation was alleviated and no metal sintering was presented after the reaction. 相似文献
996.
《International Journal of Hydrogen Energy》2021,46(70):34652-34662
The release behavior of biomass and coal in the co-pyrolysis process was investigated. The release characteristics of the small molecules from 100 to 1000 °C were researched by TG-MS at the heating rate of 30 °C/min. The pyrolysis products during the co-pyrolysis process were compared with that in the separate pyrolysis process. It is found that the changes of pyrolysis products in the co-pyrolysis process are similar to that in the separate pyrolysis process. The main pyrolysis products of the biomass are released at the temperature lower than 500 °C. Some of the small molecules of Shenfu coal release at the temperature higher than 900 °C. The yields of aromatic compounds in biomasses are lower than that in Shenfu coal. In addition, most of the raw materials are pyrolyzed independently during the co-pyrolysis process. The differences between the experimental values and calculated values are slightly. With the addition of biomass, the content variations of aromatic compounds are not significant. 相似文献
997.
《能源学会志》2021
Pine sawdust (PS) was gasified in a drop-tube reactor (DTR) using air as a gasifying agent. An almost complete mass balance was achieved by establishing a burning operation after gasification to determine the carbon deposits (CD) inside the reactor tube, providing an authentic depiction of the feedstock conversion. The results indicated that particle size reduction led to a significant improvement in the gasification performance. When the particle size of PS was below 0.25 mm, almost complete char gasification was achieved at 1300 °C, while soot remained a major particulate in the syngas. An experimental approach is proposed to simulate the axial temperature gradient (ATG) inside an auto-thermal entrained-flow gasifier by setting two different temperature zones in the DTR. The results revealed that char was rapidly and almost completely exhausted in the high-temperature zone (1300 °C). When the ATG between the upper and lower heater zones was above 300 °C, both homogeneous reforming and heterogeneous gasification proceeded slowly or almost stagnated in the lower temperature zone. An evident enhancement of soot formation was observed at ATG = 200 °C. After that, the soot yield monotonously decreased with decreasing ATG due to the substantial enhancement of the heterogeneous gasification kinetics, contributing more to carbon conversion and CGE than char gasification. 相似文献
998.
《International Journal of Hydrogen Energy》2022,47(7):4394-4425
Demands for the decline of CO2 emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with ever-increasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed. 相似文献
999.
《International Journal of Hydrogen Energy》2022,47(58):24651-24668
There is a need to derive hydrogen from renewable sources, and the innovative stewardship of two natural resources, namely the Sun and forest, could provide a new pathway. This paper provides the first comparative analysis of solar-driven hydrogen production from environmental angles. A novel hydrogen production process proposed in this paper, named Solar-Driven Advanced Biomass Indirect-Gasification (SABI-Hydrogen), shows promise toward achieving continuous operation and scalability, the two key challenges to meet future energy needs. The calculated Global Warming Potential for 1 kg of solar-driven hydrogen production is 1.04 kg CO2-eq/kg H2, less than half of the current biomass gasification process which emits 2.67 kg CO2-eq/kg H2. Further, SABI-Hydrogen demonstrates the least-carbon intensive pathway among all current hydrogen production methods. Thus, solar-driven hydrogen production from biomass could lead to a sustainable supply, essential for a low-carbon energy transition. 相似文献
1000.
《International Journal of Hydrogen Energy》2022,47(88):37648-37667
Compression ignition (CI) engines used in the transportation sector operates on fossil diesel and is one of the biggest causes of air pollution. Numerous studies were carried out over last two decades to substitute the fossil diesel with biofuels so that the net carbon dioxide (CO2) emission can be minimized. However, the engine performance with these fuel was sub-standard and there were many long-term issues. Therefore, many researchers inducted hydrogen along with the biofuels. The present study gives an outlook on the effect of hydrogen addition with biodiesel/vegetable oil from various sources in CI engine. Engine parameters (brake thermal efficiency, brake specific fuel consumption), combustion parameters (in-cylinder pressure and heat release rate) and emission parameters (unburned hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx) and smoke emissions) were evaluated in detail. The results show that hydrogen induction in general improves the engine performance as compared to biodiesel/vegetable oil but it is similar/lower than diesel. Except NOx emissions all other emissions showed a decreasing trend with hydrogen addition. To counter this effect numerous after-treatment systems like selective catalytic reduction (SCR), exhaust gas recirculation (EGR), selective non-catalytic reduction system (SNCR) and non-selective catalytic reduction system (NSCR) were proposed by researchers which were also studied in this review. 相似文献