Artículos (Ingeniería Química y Ambiental)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11382

Examinar

Mostrando 1 - 20 de 312

Multi-scale toughening of UHPC: synergistic effects of carbon microfibers and nanotubes
(MDPI, 2025-04-21) Ruiz Martínez, Jaime Delfino; Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras; Universidad de Sevilla. TEP142: Ingeniería de Residuos
This study investigates multi-scale reinforcement of Ultra-High-Performance Concrete through targeted modifications of its mechanical and fracture-resistant properties via carbon microfibers and carbon nanotubes. The research employed comprehensive characterization techniques including workability tests, mercury porosimetry for microscale porosity analysis, and X-ray tomography for macro-scale pore evaluation. Mechanical performance was assessed through compression strength, tensile strength, and fracture energy measurements. Results demonstrated significant performance enhancements testing UHPC samples with 6 mm carbon microfibers (9 kg/m3) and varying carbon nanotubes dosages (0.11–0.54 wt%). The addition of carbon microfibres improved compressive strength by 12%, while incorporating 0.54 wt% carbon nanotubes further increased strength by 24%. Remarkably, the combined reinforcement strategy yielded a 313% increase in tensile strength compared to the reference mixture. The synergistic effect of carbon fibers and carbon nanotubes proved particularly effective in enhancing concrete performance. This multi-scale reinforcement approach presents a promising alternative to traditional steel fiber reinforcement, offering superior mechanical properties and potential advantages in corrosive environments.
Hydrogen production from supercritical water reforming of acetic acid, acetol, 1-butanol and glucose over Ni-based catalyst
(Elsevier, 2018-08) Gutiérrez Ortiz, Francisco Javier; Campanario Canales, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
Supercritical water reforming (SCWR) of four main constituents of bio-oil aqueous phase (acetic acid, acetol, 1-butanol and glucose) to produce hydrogen was studied in a tubular fixed-bed reactor using commercial Ni/Al2O3-SiO2 catalyst. The process was carried out under different operating conditions at 240 bar (500–800 °C, 5.0–22.5 wt.% of organic compounds and values of weight-hourly space velocity (WSHV) of 2.5–22.5 gorg-comp h−1 gcat−1). The data were reported as reaction rates, expressed as turnover frequencies (TOF), and the Arrhenius parameters (pre-exponential factor and apparent activation energy) were obtained. The process performance was compared to that without using any catalyst and that regarding equilibrium condition. Hydrogen yields were very close to those values predicted by equilibrium within the operating window tested in this study.
Understanding the evolution of particle size dispersion with time in a fluidised bed granulation process
(Elsevier, 2023-06) Cronin, Kevin; Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
Minimisation of final size dispersion remains an important objective of fluidised bed granulation. Some of the factors that control the evolution of the granule size distribution with time in such a process are examined using a validated aggregation model. The aim is to understand the intrinsic behaviour of size dispersion versus time with an approach that is not specific to a particular system of fluidised granulation. Because relative size dispersion (size dispersion compared to the mean size) is also important, the study also examines the evolution of mean granule size versus time. The model includes an aggregation rate that is time and size dependent and a granule kinetic energy dissipation mechanism. The relative importance of these components of the model is quantified in terms of how they control the output and it is shown that the action of the energy absorption mechanism (implemented using the viscous Stokes criterion) makes the dominant contribution although the interplay with the other effects is also significant. Mean granule volume monotonically approaches a quasi-stable asymptotic value while standard deviation in granule volume passes through a peak value before falling to a lower, quasi-stable asymptotic value. The reasons underlying such behaviour are outlined. Two new temporal parameters, an equivalent aggregation time constant and a Stokes time constant, are developed and can be employed to predict and interpret system behaviour. Such knowledge can then be applied to suggest how dispersion in size can be controlled within certain intrinsic limits, which will be of interest to the industry.
Techno-economic assessment of biogas plant upgrading by adsorption of hydrogen sulfide on treated sewage–sludge
(Elsevier, 2016-10) González Aguilera, Paloma; Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
Biogas plant upgrading by adsorption of hydrogen sulfide on treated sewage–sludge was techno-economically assessed. Three different processes were included in the study: the desulfurization of biogas by adsorption, the in-situ regeneration of the adsorbent and its production from sewage-sludge. Biogas plant upgrading was performed for a flow rate of 1000 Nm3/h of biogas with a H2S concentration of 2000 ppmv and a breakthrough concentration of 200 ppmv, which is the technical limit value for internal combustion engines. The cost due to the steam required for the in-situ regeneration was evaluated in two different scenarios: as a bought external utility and as an in-situ produced utility, installing an electric or a biogas steam boiler. According to the cash flow analysis carried out, all the options require a similar minimum selling price for the upgraded biogas (about 0.27–0.29 €/Nm3), with a cost of the overall desulfurization process between 2.5 and 4.0 c€/Nm3.
Life cycle assessment of the Fischer-Tropsch biofuels production by supercritical water reforming of the bio-oil aqueous phase
(Elsevier, 2020-11) Gutiérrez Ortiz, Francisco Javier; Alonso-Fariñas, Bernabé; Campanario Canales, Francisco Javier; Kruse, Andrea; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
This paper is aimed at performing an environmental evaluation regarding biofuel production. The process combines four sections: biomass fast pyrolysis to bio-oil with two phases, oil-phase upgrading by hydrotreating, using H2 obtained by steam reforming, and a new process to produce Fischer-Tropsch biofuels from supercritical water reforming of the aqueous phase. This phase can be valorised in the latter process entirely so natural gas is reformed to H2 (case-study 1), or partially so a fraction of this aqueous phase is reformed (case-study 2), or all this phase is reformed to H2 (case-study 3). The two former can include CO2 storage and aqueous phase concentrations were 15, 25 and 35 wt% organic compounds. At 25 wt%, the global warming potential is 11 g CO2-eq/MJ-biofuel for the case 2 with CO2 storage, while it was 11.3, 12.6, 27.7 and 34 g CO2-eq/MJ-biofuel for the cases 3, 2 without CO2 storage, 1 with and without CO2 storage, respectively. Thus, the case-study 2 with CO2 storage gives the minimum global warming potential, allowing significant reductions with respect to the use of fossil fuels. For the other categories, the case-study1 presents the lowest impacts. Similar trends are found at 15 and 35 wt%.
Assessing sediment toxicity risks with bioavailable metal fractions: new factors and index applied to the Colombian tropical Andes hotspot
(Springer, 2025-06) Rincon-Vasquez, Ingrid Vanessa; Fohrer, Nicola; Rosado Alcarria, Daniel; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP218: Biotecnología Ambiental
Heavy metal toxicity risk assessments in sediments often rely on pseudototal concentrations, despite the higher theoretical predictive potential of bioavailable fractions. This study introduces the Bioavailable Fraction Toxicity Factor (BTf) and the Bioavailable Fraction Toxicity Index (BTI) to evaluate metal toxicity risks using a bioavailable fraction calculated as the sum of the first two steps of the Tessier sequential extraction procedure. Investigating heavy metal pollution (Cd, Cr, Cu, Mn, Ni, Pb, Zn) in the Vetas River catchment, a critical freshwater source in the Santurbán Páramo within the Tropical Andes biodiversity hotspot, the study identified artisanal and small-scale mining as the primary driver of contamination. Water and sediment of mining areas, particularly La Baja Creek and El Volcán Village, exhibited the highest concentrations of metals, with some sediment levels being categorized as strongly contaminated by the Geoaccumulation Index and Pollution Load Index and exceeding the Probable Effect Concentration threshold. Bioavailable fraction of metals in sediments were measured. Bioavailable fractions were higher in mining-affected areas, suggesting greater potential for metal release under acidic conditions. The BTf and BTI provided a more nuanced understanding of metal toxicity risks compared to pseudototal concentrations, with higher BTI values in mining-influenced sites. These findings underscore the need for mitigation measures to address heavy metal pollution and highlight the ecological importance of the Santurbán Páramo. Further research into bioremediation potential using local flora is recommended to support sustainable management practices.
A new time-dependent rate constant of the coalescence kernel for the modelling of fluidised bed granulation
(Elsevier, 2021-02) Cronin, Kevin; Gutiérrez Ortiz, Francisco Javier; Ring, Denis; Zhang, Fuweng; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
This paper presents a novel approach to the determination of the coalescence kernel for population balance modelling of a general class of batch fluidised bed aggregation systems, using a continuous sprayed-in liquid binder. Coalescence requires inter-particle collisions, the wetting of the contact surfaces and the dissipation of particle kinetic energy by the viscous squeezing of the binder film. These three sub-processes in principle depend both on the size of the contacting particles and on time. A new time-dependent aggregation rate constant of the coalescence kernel has been formulated by considering the general evolution of inter-particle collision behaviour with time. The model is implemented in MATLAB and its numerical output compared to two sets of experimental data: the granulation of glass beads with polyethylene glycol as a binder and the granulation of semolina with water. The evolution of mean and standard deviation in diameter versus time are examined as is the state of the size distribution at different stages in the process. The time-averaged aggregation rate for the glass beads evaluated as 7.59 × 10−9 m-0.5 s−1 while for the semolina it was 3.86 × 10−9 m-0.5 s−1. The agreement between numerical predictions and experiment is shown to be good, demonstrating the validity of the approach. Whilst conceptually simple, the model generates realistic output and provides a powerful insight into the underlying mechanisms of granulation.
A pilot-scale laboratory experience for an inductive learning of hydrodynamics in a sieve-tray tower
(Elsevier, 2019-10) Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
A specific inductive teaching approach for undergraduate students of Chemical Engineering bachelor’s degree based on a laboratory experience is presented. Thus, the simple experiment performed to show an aspect of theory previously taught in a classroom is overcome. The specific laboratory experience involves a sieve-tray tower whereby a binary distillation is carried out. However, the focus is not on this separation operation but in the hydrodynamics associated with the start-up of the process, which needs a boiler as an ancillary system to supply the required energy. All these process units are usually taught operating under stationary conditions, which are achieved quickly if small laboratory units are used. In this paper, the hands-on experience is performed in a pilot plant, which makes students feel closer to industry and allows them to visualize different physical phenomena. Students work with their teammates, and they can acquire technical knowledge and develop transferable skills that prepare them for their future profession in a more engaged and motivational way. From their feedback, students feel that their mood increase, because they understand the phenomena shown in the experience better when it is performed first and then explained. Therefore, the approach is very well received by the students, so this new teaching scaffolding should be more and more developed and implemented in the chemical engineering curriculum. It is rewarding for the teaching staff because the laboratory experience helps students construct meaning by themselves in a more active and efficient way. This approach makes it possible to find and correct misconceptions in the students, to demonstrate procedures and methods used in the chemical engineering and to explain particular concepts within the knowledge area. But what is more important, it makes students protagonists of their own learning and gives them more confidence.
The use of process simulation in supercritical fluids applications
(Royal Society of Chemistry, 2020-03) Gutiérrez Ortiz, Francisco Javier; Kruse, Andrea; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP135: Ingeniería Ambiental y de Procesos
The use of supercritical fluids is spreading more and more throughout the world. The interest in them and their applications is clear from the increasing number of papers and patents in the last few years, as well as by the number of new research groups and facilities. When applied to process engineering, mathematical modelling is a powerful tool to gain insight into the impact of the process parameters under a large variety of conditions, which reduces the required experimentation and, hence, the economic and time resources. This review deals with modelling at molecule scale (molecular dynamics) and, more specifically, at macroscale (thermodynamic methods) in order to estimate thermodynamic and transport properties as well as the kinetic parameters needed for the subsequent process simulation. This latter is usually performed for chemical and energy processes, such as supercritical water gasification, supercritical water oxidation, biodiesel production using supercritical methanol and different applications of supercritical carbon dioxide, among others. As a further step, this type of simulation can be refined using computational fluid dynamics, thus optimizing the design of process units involved in specific processes in a rigorous way. Many recent papers are discussed in the context of simulation and modelling related to supercritical fluids applications, taking into account the software used to perform this type of study.
Integral energy valorization of municipal solid waste reject fraction to biofuels
(Elsevier, 2019-01) Gutiérrez Ortiz, Francisco Javier; Kruse, Andrea; Ramos, F.; Ollero de Castro, Pedro Antonio; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
Nowadays, the waste generation increases more and more, especially of the municipal solid waste. The municipal solid waste reject fraction may be valorized from an energy point of view. With this aim, a conceptual design of a process was developed by considering material and energy integration, which mainly consists of three sub-processes: fast pyrolysis of municipal solid waste to produce bio-oil, supercritical water reforming of the bio-oil aqueous phase to produce hydrogen to be used in the third section, which is the upgrading of the organic phase of the bio-oil by hydrodeoxygenation. The overall system was simulated using Aspen Plus software to achieve the highest process performance and the lowest utilities requirement. The former was assessed by the biofuel production (liquefied fuel gas, gasoline and diesel) and the net electrical power. In addition, the potential economic profitability of the plant was performed by specifying the main process units. Thus, for a feeding of 50 t/h of municipal solid waste reject fraction, a generation of a net electric power equal to 10.65 MWe and a production of 5.2 t/h biofuels (21.1% of the carbon present in the municipal solid waste) may be achieved, thus obtaining a very low gate fee (16.7 €/t) using the same industrial selling prices that those of fossil fuels and electricity in a full plant. Therefore, the process seems to be technically and economically feasible.
Modeling of fixed-bed columns for gas physical adsorption
(Elsevier, 2019-12) Gutiérrez Ortiz, Francisco Javier; Barragán Rodríguez, Manuel; Yang, Ralph T.; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
Adsorption processes may be classified as purification or bulk separation, depending on the feed concentration of the compounds to be adsorbed (adsorbates). The adsorption dynamics of a fixed-bed is crucial for a well-designed adsorption process. This work focuses on physical adsorption and provides a modeling to predict the breakthrough curves using a minimum set of experimental data. The modeling does not require one to obtain key parameters from the experiment unlike other modeling found in the literature. In addition, boundary conditions, thermal effects, correlations to be used, and the homogeneous/heterogeneous modelings are discussed for 1-D modeling, after verifying that it provides the same output as 2-D modeling does. Moreover, it is demonstrated that pseudo-homogeneous modeling is realistic, so a more complex heterogeneous modeling is not necessary. The modeling has been tested against five sets of experimental data: three cases of bulk separation and two cases for purification. The simulation was carried out by Comsol Multiphysics software, and a good match between the experimental data and the simulation output was achieved, which demonstrates the applicability of the modeling, so it may be used with confidence. Purification can be modeled as an isothermal process, and no energy balance equation is needed. However, for bulk separation, noticeable thermal effects may take place due to the relatively high adsorbed gas that consequently releases a higher amount of heat; at the same time, the superficial fluid velocity is reduced due to the decrease in the flow-rate, and the gas properties change, affecting the breakthrough curves.
Hydrogen production from supercritical water reforming of glycerol over Ni/Al2O3–SiO2 catalyst
(Elsevier, 2015-05) Gutiérrez Ortiz, Francisco Javier; Campanario Canales, Francisco Javier; González Aguilera, Paloma; Ollero de Castro, Pedro Antonio; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Ministerio de Ciencia y Tecnología (MCYT). España
Hydrogen production from the supercritical water reforming of glycerol was studied in a tubular fixed-bed reactor by using a Ni-based catalyst supported on Al2O3 and SiO2. Tests were carried out at a pressure of 240 bar, temperatures of 500–800 °C, glycerol feed concentrations of 5–30 wt.%, and weight hourly space velocity from 1.25 to 22.5 gGly h−1 gCat−1 (residence time from 1.6 to 4.8 s through the bed). The dry gas is mainly composed of H2, CO2, CO, CH4. The results showed that the glycerol conversion was almost complete, except at the highest glycerol feed concentration and lowest temperature. Hydrogen yields were very close to those values predicted by equilibrium at a short residence time. Nickel on catalyst was completely reduced, and structured carbon nanotubes were encountered at glycerol concentrations higher than 20 wt.%. This study illustrates that the reforming of glycerol using supercritical water over a Ni catalyst makes it possible to reduce the reforming temperature needed when no catalyst is used (from 800 °C to 600 °C), achieving a high-yield hydrogen production, very close to equilibrium, and requiring less energy.
Effect of mixing bio-oil aqueous phase model compounds on hydrogen production in non-catalytic supercritical reforming
(Royal Society of Chemistry, 2017-10) Gutiérrez Ortiz, Francisco Javier; Campanario Canales, Francisco Javier; Ollero de Castro, Pedro Antonio; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
Bio-oil derived from biomass fast pyrolysis can be processed into fuel or some chemical products, but it has a waste aqueous phase that, however, may be valorized. Supercritical reforming of this stream, simulated using mixtures of model compounds (acetic acid, acetol, 1-butanol and glucose), was experimentally studied in a tubular reactor without using a catalyst. The effect of mixing the model compounds at different operating parameters (temperature, feed composition, and residence time) on the process performance was investigated, thus addressing an important chemical aspect of biomass-based renewable energy. The experimental dry gas composition consisted of H2, CO2, CO and CH4, although the gas yields were far from equilibrium. Hydrogen yields were normally less than 2.0 moles of H2 per mole of organic feed, which are lower than those obtained for pure compounds with the same concentration. Based on the analyzed liquid samples, a series of probable reaction pathways were proposed to explain the experimental results by considering the interactions among the compounds and their formed intermediates. Thus, under tested supercritical conditions, the residence time was insufficient to reform the formed methane into hydrogen, thus leading to lower hydrogen production.
Techno-economic assessment of an energy self-sufficient process to produce biodiesel under supercritical conditions
(Elsevier, 2017-10) Gutiérrez Ortiz, Francisco Javier; Santa-Ana, P. de; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
This paper presents a conceptual design, simulation and techno-economic assessment of an energy self-sufficient process to produce 10,000 t per year of biodiesel using supercritical methanol and propane as cosolvent. A suitable heat-integrated design of the process was performed using a part of the produced biodiesel (7.4 wt.%) to achieve the energy self-sufficiency for the plant. The simulations were performed by Aspen Plus considering a continuous multitubular reactor operating at 280 °C, 128 bar, methanol-to-oil molar ratio of 24, propane-to-methanol molar ratio of 0.05, and a residence time of 9.7 min. The use of flash separators instead of distillation columns for methanol and propane separation contribute significantly to reduce the energy requirement, with respect to other studies. Final products are high purity of methyl esters (99.8%) and glycerol (96.4%). The economic analysis of the biodiesel plant resulted in a break-even point for the biodiesel selling price of 0.479 €/kg (at 10% rate of return), so the process can compete with the existing alkali and acid catalyzed processes.
Techno-economic assessment of bio-oil aqueous phase-to-liquids via Fischer-Tropsch synthesis and based on supercritical water reforming
(Elsevier, 2017-12) Campanario Canales, Francisco Javier; Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
High energy demand along with large capital costs have been the main drawbacks of Fischer-Tropsch plants, which may call into question the economic viability of the Fischer-Tropsch process. The second issue is the focus of this paper, which presents a techno-economic assessment of biofuels production by a low-temperature Fischer-Tropsch synthesis with electricity as a co-product from supercritical water reforming of the bio-oil aqueous phase. A plant size of 60 t/h was considered and a heat-integrated process was designed to be energy self-sufficient, which includes syngas production and upgrading, as well as liquid fuels production by Fischer-Tropsch synthesis and refining. The simulation and optimization was performed with the aid of Aspen Plus, and some case-studies were performed. Using a feeding concentration of 25 wt%, 2.74 t/h biofuels and 5.72 MWe were obtained. In this case, by performing a discounted cash flow analysis, with 10% rate of return and 100% equity financing, the minimum selling prices for the refined FT-gasoline, FT-diesel and FT-jet fuel were 1.20, 0.93 and 0.26 €/kg (0.84, 0.75 and 0.20 €/L), respectively, which are competitive prices with respect to the market values of the equivalent fossil fuels. Likewise, the decrease in the selling prices as the plant capacity increases was also analyzed.
High performance regenerative adsorption of hydrogen sulfide from biogas on thermally-treated sewage-sludge
(Elsevier, 2016-05) González Aguilera, Paloma; Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
Biogas desulfurization can be performed by adsorption, although new materials are needed since commercial adsorbents are expensive. In this regard, three types of sewage-sludge were studied as precursors to obtain low-cost adsorbents in a previous paper, attaining the best precursor from a sewage-sludge that was thermally treated up to 700 °C. However, it must be regenerated to make the process feasible. To find an economical and environmentally friendly regeneration process, an experimental design was performed aimed at minimizing the use of resources such as water consumption, time and the temperature required while achieving a high rate of regeneration. The selected in-situ regeneration consists of entering firstly steam at relatively low temperature (< 250 °C), against most of published studies, followed by a second step with air. Besides, it can be performed in only 20 min, giving a large feasibility to the overall continuous adsorption process, with very low energy cost and duration for the regeneration. As a relevant result, the thermally treated sewage-sludge was regenerated up to 14 times, and although the adsorption capacity decreased 2.7% on average in each adsorption/regeneration cycle, the cost relative to the adsorbent may be reduced to 20% of the cost of using fresh adsorbent.
Prediction of fixed-bed breakthrough curves for H2S adsorption from biogas: Importance of axial dispersion for design
(Elsevier, 2016-04) González Aguilera, Paloma; Gutiérrez Ortiz, Francisco Javier; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental
An axially dispersed plug flow model with non-linear isotherm based on the linear driving force (LDF) approximation was used to predict the fixed-bed breakthrough curves for H2S adsorption from biogas on sewage sludge thermally treated. The model was implemented and solved numerically by Comsol Multiphysics software. The predicted breakthrough curves matched very well the experimental data and were clearly better than those predictions obtained in our previous work by Aspen Adsorption assuming ideal plug flow. The comparison between the present and previous models, as well as a sensitivity analysis of the model and operational parameters, revealed that the overall mass transfer coefficient is usually underestimated when axial dispersion is neglected in a scale-up from lab scale, and hence, the importance of axial dispersion for design purposes of H2S fixed-bed adsorption.
Supercritical water reforming of glycerol: Performance of Ru and Ni catalysts on Al2O3 support
(Elsevier, 2016-02) Gutiérrez Ortiz, Francisco Javier; Campanario Canales, Francisco Javier; González Aguilera, Paloma; Ollero de Castro, Pedro Antonio; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Ministerio de Ciencia y Tecnología (MCYT). España
Supercritical water reforming of glycerol was studied in a tubular fixed-bed reactor using a Ru/Al2O3 catalyst, and was compared with our previous study using a Ni-based catalyst, with the aim of enhancing the performance of a global process designed under energy self-sufficient conditions. Relatively high glycerol concentrations of up to 25 wt.% and temperatures from 500 to 800 °C were tested. Glycerol conversion was very high (>99%) at temperatures of 600 °C and above, but low at 500 and 550 °C (<50%) using the Ru/Al2O3 catalyst. The gas product (dry basis) was mainly CH4 and CO2, while H2 production was quite low, against expectations. Under the same operating conditions, the behavior of the catalysts is quite different as the Ni catalyst promotes H2 production much more than the Ru catalyst. A detailed discussion is provided on our results and those of previous studies using the Ru/Al2O3 catalyst, thus acquiring more insight into the catalyst behavior. The Ru catalyst showed a large increase in its crystalline phase after testing, although the oxidation state of ruthenium did not change.
Optimization of power and hydrogen production from glycerol by supercritical water reforming
(Elsevier, 2013-02) Gutiérrez Ortiz, Francisco Javier; Ollero de Castro, Pedro Antonio; Serrera, Ana; Galera, Sebastián; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Ministerio de Ciencia y Tecnología (MCYT). España
A process design is proposed and simulated for reforming glycerol using supercritical water aimed to produce maximum power and hydrogen in an energy self-sufficient system. The selected route takes advantage of the huge pressure energy of product gas just at the outlet of the reformer converting that into power by a turbine. The expanded product gas is conditioned by two water gas shift reactors and a pressure swing adsorption unit, so a hydrogen-rich gas stream is sent to a proton exchange membrane fuel cell to be converted into electrical energy and the pressure swing adsorption off-gas stream is used as fuel gas to provide the thermal energy required by the reforming process. The evaluation of the global efficiency of the process is carried out by energy and exergy analysis. Required glycerol feed concentration in aqueous solution was obtained for a self-sufficient process, both for pure and pretreated crude glycerol, at reforming temperatures from 600 to 1000 °C and 240 atm. Thus, reforming and preheating at 800 °C and 240 atm, it was obtained a power of 1592 kW per ton/h of glycerol, with exergy and energy efficiencies of 33.8% and 35.8%, respectively.
Methanol synthesis from syngas obtained by supercritical water reforming of glycerol
(Elsevier, 2013-03) Gutiérrez Ortiz, Francisco Javier; Serrera, Ana; Galera, Sebastián; Ollero de Castro, Pedro Antonio; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Ministerio de Ciencia y Tecnología (MCYT). España
A process for producing methanol from the synthesis gas obtained by reforming of glycerol using supercritical water is studied. The process also produces power from the huge pressure energy of product gas just at the outlet of the reformer by a turbine. The expanded product gas is conditioned in a PSA system, which has three sections so as to produce a H2-rich gas stream, a CO-rich gas stream and CO2 for sequestration. Thus, it can be achieved the feed required for the methanol synthesis. The surplus hydrogen is sent to a fuel cell to generate power, and the PSA off-gas, purge from the methanol loop and gases separated from the crude methanol are burnt in a furnace to achieve an energy self-sufficient process. By changing the reforming temperature, the water-to-glycerol mass ratio and the purge from the methanol loop, the conditions for optimizing the overall process relative to methanol and power productions were achieved. Thus, by reforming at 1000 °C and 240 atm, and performing the methanol synthesis at 250 °C and 85 atm, the optimal conditions were a water-to-glycerol mass ratio of 1.68 with a purge ratio of 0.2. Under these conditions 0.270 kg MeOH/kg glycerol and overall energy efficiency of 38.0% were obtained. The separated CO2 for sequestration is 0.38 kg/kg of glycerol.

Examinar

Envíos recientes