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Gasification Process (gasification + process)
Selected AbstractsReactor performance with primary/secondary swirl intensity and direction in coal gasification processINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2001Han Chang Cho Abstract In order to evaluate the effect of swirl direction and intensity of primary/secondary stream on pulverized coal gasification performance, a numerical study was conducted. Eulerian and Lagrangian approaches are used for the gas and solid phase, respectively. The computation code was formulated with PSI-cell method, k,, model for turbulence flow, Monte-Carlo method for radiative heat transfer, and eddy dissipation model for gas-phase reaction rate. A one-step two-reaction model is employed for the devolatilization of Kideco coal. Flow and reactor performance are varied by primary/secondary swirl intensity and direction. For weak primary swirl, the WSF region is minimized at the secondary vane angle beginning generation of internal recirculation zone and having peak coal burnout. The flame stability is improved at counterswirl rather than coswirl due to its intense shear. Meanwhile, for strong primary swirl, flow distribution and coal burnout are the reverse trend with those of weak swirl and the flame stability is somewhat enhanced at coswirl rather than counterswirl. To improve coal burnout and flame stability, it is confirmed that the swirl condition be proposed for moving the flame front position toward upstream. Copyright © 2001 John Wiley & Sons, Ltd. [source] Syngas chemical looping gasification process: Bench-scale studies and reactor simulationsAICHE JOURNAL, Issue 8 2010Fanxing Li Abstract The syngas chemical looping process co-produces hydrogen and electricity from syngas through the cyclic reduction and regeneration of an iron oxide based oxygen carrier. In this article, the reducer, which reduces the oxygen carrier with syngas, is investigated through thermodynamic analysis, experiments, and ASPEN Plus® simulation. The thermodynamic analysis indicates that the countercurrent moving-bed reducer offers better gas and solids conversions when compared to the fluidized-bed reducer. The reducer is continuously operated for 15 h in a bench scale moving-bed reactor. A syngas conversion in excess of 99.5% and an oxygen carrier conversion of nearly 50% are obtained. An ASPEN Plus® model is developed which simulates the reducer performance. The results of simulation are consistent with those obtained from both the thermodynamic analysis and experiments. Both the experiments and simulation indicate that the proposed SCL reducer concept is feasible. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] The study of fluidization fast pyrolysis of straw based on the biomass entrained flow gasificationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Dong Li Abstract Straw is considered to be a kind of low heating value biomass. A new entrained flow gasification process to utilize the straw was proposed and introduced fast pyrolysis as a straw pre-treatment unit for biomass entrained flow gasification process. This study was focused on the key factors influencing on the pyrolysis products of straw and optimized the pyrolysis condition based on the analysis results to meet the needs for biomass entrained flow gasification. Experiments were carried out at the temperature ranged from 300 to 600°C. Under certain particle size and optimized fluidization flow, the maximum liquid product yield was 43.1% at the temperature of 400°C and the maximum solid product yield was 65.6% at the temperature of 300°C. The characteristics of both liquid and solid products relevant to the gasification applications were analyzed. The results showed that the energy density of the products was far more higher than that of the crude straw. Finally, an optimal pyrolysis condition was proposed, which was considered to be a suitable feedstock solution for the biomass-slurry entrained flow gasification. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Research on alkali-catalyzed gasification of coal black liquor slurry cokes made up by five different coals,ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2007Kuang Jian-ping Abstract The black liquor from paper mills contains large quantities of sodium compounds and other organic matter, such as lignin and cellulose. The sodium compounds will provide the catalytic action in coal black liquor slurry (CBLS) gasification, while lignin and cellulose can enhance the heat value in the process of gasification. Five black liquor slurries were made from coals from different regions: Xin Wen, Huang Ling, Zao Zhuang, Shen Mu and Shen Hua. Alkali-catalyzed gasification experiments on the different samples of CBLS and coal water slurry (CWS) were made on a thermobalance and a fixed-bed reactor. The residues of gasification were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The results reveal that many mesopores and micropores exist on the surface of the CBLS coke, which play a key role in the catalytic gasification process, and sodium as a catalyst can quicken the gasification reaction rate. XRD shows that NaCl and sodium silicate are the main crystal components in dry samples of CBLS and CWS. The C-O stretching vibration peak shifting to a lower wavenumber means that the energy for the C-O stretching vibration in the CBLS carbon matrix decreases after partial gasification. Not only the coal rank but also the oxygen-containing groups and minerals influence coal coke's gasification activity. Of the five different CBLS, the gasification reactivity of CBLS made by the Huang Ling coal was found to be higher than that of the others. The higher the degree of coalification, the lower the activity of the coke. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd. [source] In Situ CO2 Capture in a Dual Fluidized Bed Biomass Steam Gasifier , Bed Material and Fuel VariationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2009G. Soukup Abstract The AER (absorption enhanced reforming) process, based on the dual fluidized bed steam gasification process, uses a bed material which, apart from its function as heat carrier, acts as a CO2 transporting agent and selectively transfers CO2 from the gasification reactor to the combustion reactor. Thus, a hydrogen-rich gas is produced (H2 55...70 vol.-%db, CH4 8...13 vol.-%db, CO 5...11 vol.-%db as well as CO2 7...20 vol.-%db). Seven different CaO containing bed materials were tested for their principal applicability to the AER process with special focus on their influence on tar production. The amount of tars was generally found to be five times lower than with conventional gasification (at 850,°C) despite the low gasification temperatures (600,700,°C). Due to these low gasification temperatures, biomass with high alkali contents (e.g., straw), indicating a low ash melting point (< 800,°C), can be used under AER conditions. In summary, the AER process is very effective owing to the integration of the heat of the chemical reaction of CO2 with CaO and the water-gas shift reaction, which are both exothermic, into the gasification and the internal reforming of primary and secondary tars, which cuts off the formation of higher tars. [source] Conversion of Biomass Based Slurry in an Entrained Flow GasifierCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2007U. Santo Abstract A two-step process, BIOLIQ, with pyrolysis and subsequent entrained flow gasification has been developed at the Forschungszentrum Karlsruhe to produce synfuel from biomass. Experiments in a 60,kW pilot-scale atmospheric entrained flow gasifier allow quantitative evaluation of the combustion behavior of biomass-based slurry, leading to a better understanding of the gasification process. [source] Experimental validation of CFD simulations of a lab-scale fluidized-bed reactor with and without side-gas injectionAICHE JOURNAL, Issue 6 2010Jian Min Abstract Fluidized-bed reactors are widely used in the biofuel industry for combustion, pyrolysis, and gasification processes. In this work, a lab-scale fluidized-bed reactor without and with side-gas injection and filled with 500,600 ,m glass beads is simulated using the computational fluid dynamics (CFD) code Fluent 6.3, and the results are compared to experimental data obtained using pressure measurements and 3D X-ray computed tomography. An initial grid-dependence CFD study is carried out using 2D simulations, and it is shown that a 4-mm grid resolution is sufficient to capture the time- and spatial-averaged local gas holdup in the lab-scale reactor. Full 3D simulations are then compared with the experimental data on 2D vertical slices through the fluidized bed. Both the experiments and CFD simulations without side-gas injection show that in the cross section of the fluidized bed there are two large off-center symmetric regions in which the gas holdup is larger than in the center of the fluidized bed. The 3D simulations using the Syamlal-O'Brien and Gidaspow drag models predict well the local gas holdup variation throughout the entire fluidized bed when compared to the experimental data. In comparison, simulations with the Wen-Yu drag model generally over predict the local gas holdup. The agreement between experiments and simulations with side-gas injection is generally good, where the side-gas injection simulates the immediate volatilization of biomass. However, the effect of the side-gas injection extends further into the fluidized bed in the experiments as compared to the simulations. Overall the simulations under predict the gas dispersion rate above the side-gas injector. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] | ||||||||||