1,720,976 research outputs found
Thermodynamic analysis of ethanol processors – PEM fuelcell systems
No full textThis work presents a simulative energy efficiency analysis performed on fuel processor – PEM fuel cell systems, considering ethanol as fuel and steam reforming or autothermal reforming as processes to produce hydrogen.
System analysis was performed on conventional configuration, where a classic reforming reactor is followed by a conventional CO clean-up section, constituted by water gas shift
and preferential CO oxidation reactors, and on innovative configuration, where the reforming unit is coupled with an innovative highly selective hydrogen membrane.
Steam to ethanol and oxygen to ethanol inlet ratios and reforming temperature are screened to identify the conditions that maximize global system efficiency. Pressure and sweep gas to ethanol inlet ratio are also considered as operative parameters in the membrane-based systems.
A comparison with the results obtained when crude-ethanol is employed as fuel is also presented and discussed
Reactor temperature profile during catalytic partial oxidation on Rh/Al2O3 catalyst in a reverse flow reactor
No full textCatalytic Partial Oxidation of Methane (CPOM) in a reverse flow reactor is a promising process for decentralized syngas and hydrogen production. This reactor configuration couples feed preheating and syngas production in the same unit through a periodic inversion of the feed. Thanks to reactor compactness, this technology is particularly indicated for small and medium scale plants. However, the higher catalyst entrance temperature obtained thanks to the internal heath exchange between the hot effluent gas and the cold feed, although positive in terms of product composition, can thermally damage the catalyst and reduce its performance and lifetime. Accurate measurements of catalyst temperature profile provide an important insight to assess the thermal stress developed during reverse flow operation. In this work, we present a systematic investigation on reactor performance and catalyst temperature profile during CPOM in a reverse flow reactor with commercial Rh/Al2O3 catalyst in pellets. Temperature profile of the catalyst bed was measured by IR thermography and product composition was measured with a continuous gas analyzer. The effect of internal heat recovery on reactor performance and catalyst thermal stress is presented and compared to steady state operation. Feed direction switching time, total flow rate and methane to oxygen ratio were investigated as process operating parameters. Data of catalyst bed temperature evolution during the flow cycle are presented and discussed. Comparison of dynamic heat integration with external feed preheating in terms of product composition and catalyst temperature profile is also presented
Analysis of the energy efficiency of innovative ATR-based PEM fuel cell system with hydrogen membrane separation
No full textIn this work we report a simulative energy efficiency analysis performed on innovative fuel
processor – PEM fuel cell systems in which hydrogen is produced via methane autothermal
reforming, separated with a membrane unit coupled with a water gas shift reactor and
then converted into electric energy by means of the PEM fuel cell.
Two basic configurations are investigated: one with the membrane unit placed downstream
the water gas shift reactor and the other with the membrane unit embedded into
the water gas shift reactor. The results are discussed and compared with the case of a fuel
processor constituted by an autothermal reforming reactor followed by two water gas shift
reactors and a preferential CO-oxidation reactor.
Pressure, steam to methane and oxygen to methane inlet ratios are explored as operation
variables. The effect of addition of steam as sweep gas into the permeate side of the
membrane is also presented and discussed
Calculation of the energy efficiency of fuel processor PEM (proton exchange membrane) fuel cell systems from fuel elementar composition and heating value
No full textThis simulative work analyzes the impact of fuel type on the energy efficiency of systems composed by a
fuel processor for hydrogen production and a PEM (proton exchange membrane) fuel cell. Two fuel
processors are simulated, one employs steam reforming to produce hydrogen, the other one autothermal
reforming. In both cases, fuel processing is completed by two water gas shift units and one preferential
CO oxidation unit.
Five classes of fuels are considered, i.e. alkanes, alkenes and alkynes, alcohols and aromatics and steam
to carbon and oxygen to carbon inlet ratios, reforming temperature, fuel cell split fraction and exhaust
gas temperature are explored as operative parameters.
For each fuel considered, Aspen Plus was used to calculate the operative conditions that maximize
the energy efficiency of the systems. For each system, the data were employed to identify an analytic
expression to calculate the best possible energy efficiency given the elementar composition of the fuel
and its lower heating value. The expressions proved to hold true for a broad range of fuel type
Methane autothermal reforming in a reverse flow reactor on Rh/Al2O3 catalyst
No full textAutothermal reforming of methane was investigated in a Reverse Flow Reactor with commercial Rh/Al2O3 catalyst in pellets. The process was carried out in a catalytic fixed bed reactor and switching of feed flow direction was obtained through four electrovalves synchronized in pair. Temperature profile of the catalyst bed was measured by fast IR thermography and product composition was measured with a continuous gas analyzer.
Reactor performance and catalyst temperature profile are presented as a function of feed direction switching period, water to methane inlet ratio and total inlet flow rate. Results are compared to steady state operation
Reactor temperature profile during methane autothermal reforming on Rh/Al2O3 catalyst
No full textCatalytic autothermal reforming of methane was studied over a commercial rhodium catalyst as a function of feed composition and oven temperature. The process is carried out in a catalytic fixed bed reactor placed in a tubular oven. Temperature profile of the catalyst bed was measured by IR thermography and product composition was measured with a continuous gas analyzer. The effect of water addition on rhodium catalyst was investigated maintaining feed preheating within the limits obtainable with typical internal heat recovery reactors. The effect of water addition on product composition was investigated as a function of reactor thermal level, regulated by acting on oven temperatur
Analysis of the energy efficiency of some butanol recovery processes
No full textThis work presents an energetic analysis of three butanol recovery processes from acetone-butanol-ethanol (ABE) fermentation broth. The processes were based on: 1) gas stripping, 2) liquid-liquid extraction, and 3) supercritical extraction. Material and energy balance simulations were carried out by commercial software Aspen Plus®. Processes were characterized in terms of energy efficiency and specific energy requirement. Operating conditions-e.g. gas stripping flow rate and solvent flow rate-were investigated and optimized with respect to the energy objective functions. © 2016, AIDIC Servizi S.r.l
Energy efficiency of membrane based Fuel Processors - PEM fuel cell systems
No full textThis work presents a simulative energy efficiency analysis performed on fuel processor – PEMFC systems, considering methane as fuel and steam reforming or autothermal reforming as processes to produce hydrogen. Computation of energy efficiency takes into account the power required by the auxiliary units, coupling of the fuel processor with the fuel cell as well as heat recovery and integration.
Two system configurations were simulated and compared: an innovative configuration,
based on an integrated membrane reactor directly coupled with the fuel cell, and
a conventional configuration, based on a classic reforming reactor followed by a conventional CO clean-up section, constituted by water gas shift and preferential CO oxidation reactors.
Reforming temperature, plant pressure, steam to methane and oxygen to methane inlet ratios were considered as process parameters. The effect of the addition of steam as sweep
gas is also presented and discussed
Techno-economic analysis of a Butanol recovery process based on gas stripping technique
No full textAcetone-Butanol-Ethanol (ABE) industrial production by fermentation is strongly affected by the low concentration of solvent (<25 g/L) that affects the cost of the recovery process. To decrease the overall cost of the butanol production, alternative routes for the recovery have proposed in literature. This paper presents a techno-economic analysis of an innovative butanol recovery process from ABE fermentation broth based on gas stripping technique. The comparison with a recovery process based on conventional distillation is also presented. The investigated recovery line included gas stripping, absorption of butanol in a selected solvent, and distillation to separate the butanol from the selected liquid. The proposed and the conventional processes were modelled by means of the commercial software Aspen Plus to assess energy and material balances. The estimation of the investment cost was carried out by using Aspen Icarus and approximated methodologies typical of the process engineering. Gas stripping flow rate, solvent flow rate, and feed preheating temperature were explored as design variables. The effect of the butanol concentration in the typical fermentation broth was also presented and discussed. From the economic point of view, the proposed process was the most convenient to recover butanol from fermentation broth. The incidence of the recovered section on the assessed butanol production cost by fermentation ranged between 0.33 and 0.92 $/kg, when butanol concentration in the fermentation broth changed in the interval 5-18 g/L
Thermodynamic analysis of ATR-based PEM fuel cell system with hydrogen membrane separation
No full textIn this work we present a simulative energy efficiency analysis on innovative fuel processor - PEM fuel cell systems in which hydrogen is produced via methane autothermal reforming (ATR), separated with a membrane unit coupled with a water gas shift (WGS) reactor and then converted into electric energy in a PEM fuel cell. The simulations were performed in stationary conditions, by using the commercial package Aspen Plus®. Fuel processors based on ATR process represent a promising technology to develop small scale hydrogen production units for stand-alone and portable power generation, due to their compactness and to fast response to load changes. These advantages are enhanced when a highly selective hydrogen separation unit is introduced in the system for pure hydrogen generation. However, the global energy efficiency of these systems and, thus, their feasibility strictly depends on fuel processor configuration and on operating parameters; therefore, a comprehensive simulative analysis on membrane-based fuel processors coupled with a PEM fuel cell will allow to identify the conditions that maximize system performance. Two system configurations are investigated: one with the membrane unit placed downstream the WGS reactor and another one with the membrane unit embedded into the WGS reactor. The results are discussed and compared with the case of a fuel processor constituted by an ATR reactor followed by two WGS reactors and a preferential CO-oxidation reactor (conventional fuel processor). Operating parameters such as steam to methane and oxygen to methane inlet ratios, as well as pressure, are screened to identify the conditions that maximize global energy efficiency. The effect of the addition of steam as sweep gas in the permeate side of the membrane unit is also presented and discussed
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