Analysis of the energy efficiency of an integrated ethanol processor for PEM fuel cell systems

Francesconi, Javier A.; Mussati, Miguel C.; Mato, Roberto O.; Aguirre, Pío A.

doi:10.1016/j.jpowsour.2006.12.109

Cited by 70 publications

(48 citation statements)

References 21 publications

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“…The electrical efficiency here achieved was higher than what reported [35] for a similar system with SRE heating provided by ethanol combustion. Slightly different system and higher efficiency has been instead reported elsewhere [19].…”

Section: -Simulation Resultscontrasting

confidence: 65%

Process simulation and optimization of H2 production from ethanol steam reforming and its use in fuel cells. 2. Process analysis and optimization

Rossetti

Compagnoni

Torli

2015

Chemical Engineering Journal

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The feasibility of power cogeneration through fuel cells using bioethanol with different concentration has been considered. Data and layout have been inspired by an existing unit Helbio, GH2 -BE-5000 (5 kWelectrical + 5 kWthermal) system for combined heat and power generation (CHP). The system is constituted by six reactors connected in series for hydrogen production and purification and by a fuel cell of the mentioned capacity.To evaluate process efficiency and the possibility to operate with diluted bioethanol feed, characterized by lower purification cost, different process layouts have been tested. Particular attention is paid to the intensification of the heat exchange network, to increase the overall plant efficiency. Heat supply to the steam reformer has been accomplished by burning part of the reformate, since diluted ethanol is not suitable to feed the burner as in the experimental process layout.The water/ethanol feeding ratio has been taken as major parameter for simulation. An increase of this variable improved H2 yield due to promotion of the water gas shift reaction and lower impact of the hydrogen-consuming methanation step. However, higher heat input was required by the reformer, implying the delivery of a higher fraction of the reformate to 1 Corresponding author: fax 0039-02-50314300; email ilenia.rossetti@unimi.it the burner instead than to the fuel cell. This means lower electric output and efficiency.However, the presence of a high enthalpy steam exhaust increased the available thermal output, with consequent increase of the thermal and overall efficiency of the plant.Keywords: Bio-ethanol steam reforming; Process simulation; H2 production; Fuel cells. -INTRODUCTIONIn order to find out alternative routes for the co-generation of heat and power (CHP) from renewable sources, different strategies have been proposed. Among these, H2 production from bioethanol, coupled to fuel cells raised considerable attention in recent years [1][2][3]. In addition, highly innovative solutions for the production of second generation biofuels are becoming available, leading to environmentally, ethically and economically sustainable bioethanol. The economical plan proposed by Biochemtex, for instance, is based on 0.3 euro/L for the production of lignocellulosic anhydrous bioethanol [4].A 250 W system based on authothermal reformer and a fuel cell stack has been studied [5].A minimum amount of process controls and little internal heat integration kept system architecture simple, as required for portable applications, at difference with the presently studied system, in which heat integration was part of the optimization. Indeed, for stationary applications the increase of efficiency is seen as a predominant factor with respect to simplification.A similar system has been proposed, with reformate purification from CO based on preferential oxidation and attention to the control logic and heat integration [6][7][8]. On a completely different scale, the technical feasibility of using existing steam reforming and...

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Section: -Simulation Resultscontrasting

confidence: 65%

Process simulation and optimization of H2 production from ethanol steam reforming and its use in fuel cells. 2. Process analysis and optimization

Rossetti

Compagnoni

Torli

2015

Chemical Engineering Journal

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“…Starting from the SR reactions, an integrated analysis of the cell power and heat needs has been performed in [32] using HYSIS ® and the flowsheet outlined below ( Figure 5), with the main findings reported in Table 4. The details of the heat analysis and its implementation with very specific HYSIS ® tools is here omitted and can be found in the cited work.…”

Section: T (°C)mentioning

confidence: 99%

“…The heat released by the fuel cell is added to the balance of the network via a closed service loop, since the LNG block cannot discharge directly a heat stream on the CU; a HU is not present because the more demanding stream (the already pre-heated reformer feed) is connected to the burner via another heat stream external to the PA block. The image is reproduced by kind permission from [32]. Copyright 2007, Elsevier.…”

Section: T (°C)mentioning

confidence: 99%

“…Selection of data from reference [32]; the maximum fraction of methane in every stream is always lower than 2.5%. Overall PFD for the ethanol reforming as described in [32]: the pumps are for water (above) to the reformer, fed with fresh water and condensate from the reacted mixture and from the cell, and ethanol (below) to the reformer (after mixing with water) and directly to the burner. Air to the burner, to the byproducts oxidizer ("PrOx") and to the cell is provided by the compressors in the lower middle of the scheme.…”

Section: T (°C)mentioning

confidence: 99%

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Process Simulation for the Design and Scale Up of Heterogeneous Catalytic Process: Kinetic Modelling Issues

et al. 2017

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Abstract:Process simulation represents an important tool for plant design and optimization, either applied to well established or to newly developed processes. Suitable thermodynamic packages should be selected in order to properly describe the behavior of reactors and unit operations and to precisely define phase equilibria. Moreover, a detailed and representative kinetic scheme should be available to predict correctly the dependence of the process on its main variables. This review points out some models and methods for kinetic analysis specifically applied to the simulation of catalytic processes, as a basis for process design and optimization. Attention is paid also to microkinetic modelling and to the methods based on first principles, to elucidate mechanisms and independently calculate thermodynamic and kinetic parameters. Different case studies support the discussion. At first, we have selected two basic examples from the industrial chemistry practice, e.g., ammonia and methanol synthesis, which may be described through a relatively simple reaction pathway and the relative available kinetic scheme. Then, a more complex reaction network is deeply discussed to define the conversion of bioethanol into syngas/hydrogen or into building blocks, such as ethylene. In this case, lumped kinetic schemes completely fail the description of process behavior. Thus, in this case, more detailed-e.g., microkinetic-schemes should be available to implement into the simulator. However, the correct definition of all the kinetic data when complex microkinetic mechanisms are used, often leads to unreliable, highly correlated parameters. In such cases, greater effort to independently estimate some relevant kinetic/thermodynamic data through Density Functional Theory (DFT)/ab initio methods may be helpful to improve process description.

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“…The presence of the SEP unit allows to model a purge gas (anode off-gas, AOG) required for mass balance reasons, whenever the hydrogen stream sent to the PEM fuel cell is not 100% pure. In agreement with the literature, the hydrogen split fraction in the stream H2 at the outlet of the SEP was fixed at 0.75 (Francesconi et al, 2007), whereas the split fractions of all the other components were taken as 0. The RSTOIC unit models the hydrogen oxidation reaction occurring in the fuel cell.…”

Section: H-hts Hmentioning

confidence: 98%

The energy efficiency of onboard hydrogen storage

Jensen

Vestbø

et al. 2007

Journal of Alloys and Compounds

118

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Analysis of the energy efficiency of an integrated ethanol processor for PEM fuel cell systems

Cited by 70 publications

References 21 publications

Process simulation and optimization of H2 production from ethanol steam reforming and its use in fuel cells. 2. Process analysis and optimization

Process simulation and optimization of H2 production from ethanol steam reforming and its use in fuel cells. 2. Process analysis and optimization

Process Simulation for the Design and Scale Up of Heterogeneous Catalytic Process: Kinetic Modelling Issues

The energy efficiency of onboard hydrogen storage

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