The Experts below are selected from a list of 15327 Experts worldwide ranked by ideXlab platform
James J. Leahy - One of the best experts on this subject based on the ideXlab platform.
-
Fly Ash Characterization from Cynara cardunculus L. Gasification
Energy & Fuels, 2018Co-Authors: Daniel Serrano, Marzena Kwapinska, S. Sánchez-delgado, James J. LeahyAbstract:This study analyzes the characteristics of fines produced during the air-blown gasification of Cynara cardunculus L. in a bubbling fluidized bed. These fines are collected by means of two hot cyclones and a hot filter. The gasification temperature is varied from 700 to 800 °C using olivine and magnesite as bed materials, with an equivalence ratio of 0.2. Relatively high carbon content is found in the entrained fines for all experiments. The Lower Heating Value of the elutriated fines varies from 5.2 to 9.4 MJ/kgdb. Around 75% of the fines are captured in the first cyclone, 5% in the second cyclone, and the remaining 20% in the hot filter. The concentration of elements such as Se and Cl makes these fly ashes a hazardous material. Based on these properties the potential reuse of fly ashes is evaluated.
-
artificial neural network based modelling approach for municipal solid waste gasification in a fluidized bed reactor
Waste Management, 2016Co-Authors: Daya Shankar Pandey, James J. Leahy, Saptarshi Das, Indranil Pan, Witold KwapinskiAbstract:In this paper, multi-layer feed forward neural networks are used to predict the Lower Heating Value of gas (LHV), Lower Heating Value of gasification products including tars and entrained char (LHVp) and syngas yield during gasification of municipal solid waste (MSW) during gasification in a fluidized bed reactor. These artificial neural networks (ANNs) with different architectures are trained using the Levenberg–Marquardt (LM) back-propagation algorithm and a cross validation is also performed to ensure that the results generalise to other unseen datasets. A rigorous study is carried out on optimally choosing the number of hidden layers, number of neurons in the hidden layer and activation function in a network using multiple Monte Carlo runs. Nine input and three output parameters are used to train and test various neural network architectures in both multiple output and single output prediction paradigms using the available experimental datasets. The model selection procedure is carried out to ascertain the best network architecture in terms of predictive accuracy. The simulation results show that the ANN based methodology is a viable alternative which can be used to predict the performance of a fluidized bed gasifier.
Peter Wasserscheid - One of the best experts on this subject based on the ideXlab platform.
-
solid oxide fuel cell operating on liquid organic hydrogen carrier based hydrogen making full use of heat integration potentials
International Journal of Hydrogen Energy, 2018Co-Authors: Patrick Preuster, Qingping Fang, Roland Peters, Robert Deja, Van Nhu Nguyen, Ludger Blum, Detlef Stolten, Peter WasserscheidAbstract:Abstract Our contribution demonstrates the technological potential of coupling Liquid Organic Hydrogen Carrier (LOHC)-based hydrogen storage and hydrogen-based Solid Oxide Fuel Cell (SOFC) operation. As SOFC operation creates waste heat at a temperature level of more than 600 °C, clever heat transfer from the SOFC operation to the LOHC dehydrogenation process is possible and results in an overall efficiency of 45% (electric output of SOFC vs. Lower Heating Value of LOHC-bound hydrogen). Moreover, we demonstrate that LOHC vapour does not harm the operational stability of a typical 150 W SOFC short stack. By operating the stack with LOHC-saturated hydrogen, operation times of more than 10 years have been simulated without noticeable degradation of SOFC performance.
Marc A Rosen - One of the best experts on this subject based on the ideXlab platform.
-
process simulation and analysis of a five step copper chlorine thermochemical water decomposition cycle for sustainable hydrogen production
International Journal of Energy Research, 2014Co-Authors: Mehmet F Orhan, Ibrahim Dincer, Marc A RosenAbstract:SUMMARY A process model of a five-step copper–chlorine (Cu–Cl) cycle is developed and simulated with the Aspen Plus simulation code. Energy and mass balances, stream flows and properties, heat exchanger duties, and shaft work are determined. The primary reactions of the five-step Cu–Cl cycle are assessed in terms of varying operating and design parameters. A sensitivity analysis is performed to examine the effect of parameter variations on other variables, in part to assist optimization efforts. For each cycle step, reaction heat variations with such parameters as process temperature are described quantitatively. The energy efficiency of the five-step Cu–Cl thermochemical cycle is found to be 44% on the basis of the Lower Heating Value of hydrogen, and a parametric study of potential efficiency improvement measures is presented. Copyright © 2014 John Wiley & Sons, Ltd.
-
design of systems for hydrogen production based on the cu cl thermochemical water decomposition cycle configurations and performance
International Journal of Hydrogen Energy, 2011Co-Authors: Mehmetfatih Orhan, Ibrahim Dincer, Marc A RosenAbstract:Abstract In this study, we analyze several Cu-Cl cycles by examining various design schemes for an overall system and its components, in order to identify potential performance improvements. The factors that determine the number and effective grouping of steps for new design schemes are analyzed. A thermodynamic analysis and several parametric studies are presented for various configurations. The energy efficiency is found to be 44% for the five-step thermochemical process, 43% for the four-step process and 41% for the three-step process, based on the Lower Heating Value of hydrogen. Also, conclusions regarding implementation of these new configurations are discussed and the potential benefits ascertained.
Chihwa Wang - One of the best experts on this subject based on the ideXlab platform.
-
biomass gasification with co2 in a fluidized bed
Powder Technology, 2016Co-Authors: Yongpan Cheng, Zhihao Thow, Chihwa WangAbstract:Abstract Biomass gasification with CO2 as the gasifying agent is a promising way to relieve the energy shortage and minimize CO2 emission. In this study, Eulerian method was used to study the CO2 gasification of biomass in a fluidized bed gasifier. It was found that the CO2 percentage in the gasifying mixture with air, the CO2-to-biomass ratio, the moisture content of woodchips, and the woodchip size had great influence on the gasification performance. With the increasing CO2-to-biomass ratio, the mole fraction of CO in the producer gases would be increased while those of H2 and CO2 vary in the opposite trend. When CO2 mass percentage in the gasifying agent was 60%, the fractions of CO and CH4 in the producer gas reached the maximum, as well as the Lower Heating Value and cold gas efficiency, so this was the optimal condition when the gasifier had the best performance. The moisture content and particle size of the woodchips had negative effects on the gasification performance, because of the Lower Heating Value of producer gases, cold gas efficiency and CO2 conversion ratio were both reduced with increasing moisture content and particle size. This study offers a promising way to integrate the gasification of renewable biomass with CO2 capture, and may be helpful in the design and operation of biomass gasifier.
-
co gasification of woody biomass and sewage sludge in a fixed bed downdraft gasifier
Aiche Journal, 2015Co-Authors: Yongpan Cheng, Thawatchai Maneerung, Yen Wah Tong, Chihwa WangAbstract:Experimental and numerical studies of cogasification of woody biomass and sewage sludge have been carried out. The gasification experiments were performed in a fixed-bed downdraft gasifier and the experimental results show that 20 wt % dried sewage sludge in the feedstock was effectively gasified to generate producer gas comprising over 30 vol % of syngas with an average Lower Heating Value of 4.5 MJ/Nm3. Further increasing sewage sludge content to 33 wt % leads to the blockage of gasifier, which is resulted from the formation of agglomerated ash. The numerical models were then developed to simulate the reactions taking place in four different zones of the gasifier (i.e., drying, pyrolysis, combustion, and reduction zones) and to predict the producer gas composition and cold gas efficiency. The deviation between the numerical and experimental results obtained was Lower than 10%. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2508–2521, 2015
Kevin Mcdonnell - One of the best experts on this subject based on the ideXlab platform.
-
bubbling fluidised bed gasification of wheat straw gasifier performance using mullite as bed material
Chemical Engineering Research & Design, 2015Co-Authors: Sean Mac An T Bhaird, Phil Hemmingway, Eilin Walsh, Amado L Maglinao, Sergio C Capareda, Kevin McdonnellAbstract:Abstract The adoption of wheat straw as a fuel for gasification processes has been hindered due to a lack of experience and its propensity to cause bed agglomeration in fluidised bed gasifiers. In this study wheat straw was gasified in a small scale, air blown bubbling fluidised bed using mullite as bed material. The gasifier was successfully operated and isothermal bed conditions maintained at temperatures up to 750 °C. Below this temperature, the gasifier was operated at equivalence ratios from 0.1 to 0.26. The maximum Lower Heating Value of the producer gas was approximately 3.6 MJ m −3 at standard temperature and pressure (STP) conditions and was obtained at an equivalence ratio of 0.165. In general, a producer gas with a Lower Heating Value of approximately 3 MJ m −3 at STP could be obtained across the entire range of equivalence ratios operated. The Lower Heating Value tended to fluctuate, however, and it was considered more appropriate for use in heat applications than as a fuel for internal combustion engines. The concentration of combustibles in the producer gas was Lower than that obtained from the gasification of wheat straw in a dual distributor type gasifier and a circulating fluidised bed. These differences were associated with reactor design and, in the case of the circulating fluidised bed, with higher temperatures. Equilibrium modelling at adiabatic conditions, which provides the maximum performance of the system, showed that the gasifier was operating at suboptimal equivalence ratios to achieve greatest efficiencies. The maximum calculated theoretical cold gas efficiency of 73% was obtained at an equivalence ratio of 0.35.
