h i g h l i g h t s " Devolatilization tests were conducted between 600°C and 900°C. " Detailed a... more h i g h l i g h t s " Devolatilization tests were conducted between 600°C and 900°C. " Detailed analysis of tars and light hydrocarbons was performed. " Steam concentration (0-30 vol%) hardly influences tar and hydrocarbon yields. " Stoichiometric formula of tar was estimated by elemental analysis of tar. " Correlations between tar and light hydrocarbon yields were obtained.
ABSTRACT A process for producing methanol from the synthesis gas obtained by reforming of glycero... more ABSTRACT 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.
A simple treatment for obtaining the solution of single isothermal gas–solid non-catalytic reacti... more A simple treatment for obtaining the solution of single isothermal gas–solid non-catalytic reactions is presented. The model is formulated under a local volumetric approach and permits to incorporate non-linear chemical kinetics and the change in porous structure during conversion. The methodology developed in this work is based on the quantize method for decoupling the solid and gas equations and on
Kinetic studies were conducted to elucidate the effects of diffusional limitations at particle sc... more Kinetic studies were conducted to elucidate the effects of diffusional limitations at particle scale during thermogravimetry analysis (TGA) char reactivity tests. The main objective was to identify the limiting phenomena that may occur during biomass char gasification experiments with CO 2. The char used was wood matter from pressed-oil stone (WPOS) (this is also called orujillo). The gasification rates of WPOS were measured at four different particle sizes (0.06, 0.9, 1.2, and 2.1 mm), three CO 2 partial pressures (0.20, 0.35, and 0.50 bar), and four temperatures (800, 850, 900, and 950°C). Literature on single-particle studies and diffusional effects that occur in char gasification kinetic experiments were critically surveyed. We found neither general criteria for a kinetic model to be selected nor a quantitative consensus about the impact of variables such as particle size on the diffusional interferences. Our own experiments indicate the extraordinary importance of the diffusional effects at high temperature and large particle size, i.e., a large Thiele modulus. The CO 2 partial pressure was seen to have a secondary role, compared to temperature and particle size, within the range analyzed. The results presented in this study reveal that biomass-derived char particles inside industrial gasifiers may be limited by diffusional effects. Consequently, suitable kinetic-particle models that capture plausible physical limitations should be used when simulating such gasifiers. In the second part of this work, which is given in a companion paper [Energy Fuels 2006, 20, xxxx], a simple particle model is developed and validated with the experimental results reported in the present article.
Industrial Engineering Chemistry Research, Nov 11, 2008
Presently, decentralized feedback control is the only control strategy used in wet limestone flue... more Presently, decentralized feedback control is the only control strategy used in wet limestone flue gas desulfurization (WLFGD) plants. Proper tuning of this control strategy is becoming an important issue in WLFGD plants because more stringent SO 2 regulations have come into force recently. 3 Controllability analysis is a highly valuable tool for proper design of control systems, but it has not been applied to WLFGD plants so far. In this paper a decentralized control strategy is designed and applied to a WLFGD pilot plant taking into account the conclusions of a controllability analysis. The results reveal that good SO 2 control in WLFGD plants can be achieved mainly because the main disturbance of the process is well-aligned with the plant and interactions between control loops are beneficial to SO 2 control.
... AL Villanueva Perales*, P. Ollero, FJ Gutiérrez Ortiz and F. Vidal B. Departamento de Ingeni... more ... AL Villanueva Perales*, P. Ollero, FJ Gutiérrez Ortiz and F. Vidal B. Departamento de Ingeniería Química y Ambiental, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092, Seville, Spain. Ind. Eng. Chem. Res. ...
2Nd International Congress of Energy and Environment Engineering and Management, 2007
... Pedro Ollero a ... Equilibrium prediction is extended by incorporation some actions: (1) a ps... more ... Pedro Ollero a ... Equilibrium prediction is extended by incorporation some actions: (1) a pseudo-empirical prediction of the yields of char, tar and methane from the flaming pyrolysis processes and, (2) estimations of the unconverted fractions of these three components in the ...
In fluidized-bed gasification (FBG) of biomass and waste the temperature is maintained low enough... more In fluidized-bed gasification (FBG) of biomass and waste the temperature is maintained low enough to avoid agglomeration. This decreases carbon conversion and generates a tarry gas, reducing process efficiency and the gas utilization. In the present work optimization of FBG to achieve high char and tar conversion in the reactor is studied. Staged gasification is identified as a rational way to achieve the target with reasonable complexity and cost, so it is an ideal method for power production in small/medium biomass gasification plants. A recent development based on a tree-stage fluidized bed gasification system, is presented.
ABSTRACT In this work, two options are investigated to enhance the economics of the catalytic pro... more ABSTRACT In this work, two options are investigated to enhance the economics of the catalytic production of bioethanol from biomass gasification by exploiting the excess of CO2 emission saving: (i) to import fossil energy, in the form of natural gas and electricity or (ii) to trade CO2 emissions. To this end, an integrated life cycle and economic assessment is carried out for four process configurations, each using a different light hydrocarbon reforming technology: partial oxidation, steam methane reforming, tar reforming and autothermal reforming. The results show that for all process configurations the production of bioethanol and other alcohols significantly increases when natural gas displaces biomass, maintaining the total energy content of the feedstock. The economic advantage of the partial substitution of biomass by natural gas depends on their prices and this is explored by carrying out a sensitivity analysis, taking historical prices into account. It is also concluded that the trade of CO2 emissions is not cost-competitive compared to the import of natural gas if the CO2 emission price remains within historical European prices. The CO2 emission price would have to double or even quadruple the highest CO2 historical price for CO2 emission trading to be a cost-competitive option.
ABSTRACT Abstract In this study, a simplified methodology for the calculation of the balance of g... more ABSTRACT Abstract In this study, a simplified methodology for the calculation of the balance of greenhouse gas (GHG) emissions and corresponding saving compared with the fossil reference is presented. The proposed methodology allows the estimation of the anthropogenic GHG emissions of thermochemical biorefineries (net emitted to the atmosphere). In the calculation of the GHG balance, all relevant factors have been identified and analyzed including multiproduction, emissions from biogenic carbon capture and storage (Bio-CCS), co-feeding of fossil fuels (secondary feedstock) and possible carbon storage in biomass-derived products (chemicals). Therefore, it is possible to calculate the balance of GHG emissions of a hypothetical thermochemical biorefinery considering different alternatives of land-use, biomass feedstock, co-feeding of fossil fuels, Bio-CCS incorporation and final use of the products. The comparison of the estimated GHG balance with the corresponding fossil reference for each product is of special relevance in the methodology since it is the parameter used in European regulation for the fulfillment of sustainability criteria in biomass-derived fuels and liquids. The proposed methodology is tested using a previously assessed set of different process concepts of thermochemical biorefineries (techno-economic analysis). The resulting GHG balance and saving are analyzed to identify uncertainties and provide recommendations for future regulation. In all process concepts, the GHG savings are above the minimum requirement of GHG emissions for 2018. In the case of incorporating Bio-CCS, cradle-to-grave negative GHG emissions are obtained. However, in order to assess the role of chemical co-production from biomass, they need to be included in future regulation.
h i g h l i g h t s " Devolatilization tests were conducted between 600°C and 900°C. " Detailed a... more h i g h l i g h t s " Devolatilization tests were conducted between 600°C and 900°C. " Detailed analysis of tars and light hydrocarbons was performed. " Steam concentration (0-30 vol%) hardly influences tar and hydrocarbon yields. " Stoichiometric formula of tar was estimated by elemental analysis of tar. " Correlations between tar and light hydrocarbon yields were obtained.
ABSTRACT A process for producing methanol from the synthesis gas obtained by reforming of glycero... more ABSTRACT 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.
A simple treatment for obtaining the solution of single isothermal gas–solid non-catalytic reacti... more A simple treatment for obtaining the solution of single isothermal gas–solid non-catalytic reactions is presented. The model is formulated under a local volumetric approach and permits to incorporate non-linear chemical kinetics and the change in porous structure during conversion. The methodology developed in this work is based on the quantize method for decoupling the solid and gas equations and on
Kinetic studies were conducted to elucidate the effects of diffusional limitations at particle sc... more Kinetic studies were conducted to elucidate the effects of diffusional limitations at particle scale during thermogravimetry analysis (TGA) char reactivity tests. The main objective was to identify the limiting phenomena that may occur during biomass char gasification experiments with CO 2. The char used was wood matter from pressed-oil stone (WPOS) (this is also called orujillo). The gasification rates of WPOS were measured at four different particle sizes (0.06, 0.9, 1.2, and 2.1 mm), three CO 2 partial pressures (0.20, 0.35, and 0.50 bar), and four temperatures (800, 850, 900, and 950°C). Literature on single-particle studies and diffusional effects that occur in char gasification kinetic experiments were critically surveyed. We found neither general criteria for a kinetic model to be selected nor a quantitative consensus about the impact of variables such as particle size on the diffusional interferences. Our own experiments indicate the extraordinary importance of the diffusional effects at high temperature and large particle size, i.e., a large Thiele modulus. The CO 2 partial pressure was seen to have a secondary role, compared to temperature and particle size, within the range analyzed. The results presented in this study reveal that biomass-derived char particles inside industrial gasifiers may be limited by diffusional effects. Consequently, suitable kinetic-particle models that capture plausible physical limitations should be used when simulating such gasifiers. In the second part of this work, which is given in a companion paper [Energy Fuels 2006, 20, xxxx], a simple particle model is developed and validated with the experimental results reported in the present article.
Industrial Engineering Chemistry Research, Nov 11, 2008
Presently, decentralized feedback control is the only control strategy used in wet limestone flue... more Presently, decentralized feedback control is the only control strategy used in wet limestone flue gas desulfurization (WLFGD) plants. Proper tuning of this control strategy is becoming an important issue in WLFGD plants because more stringent SO 2 regulations have come into force recently. 3 Controllability analysis is a highly valuable tool for proper design of control systems, but it has not been applied to WLFGD plants so far. In this paper a decentralized control strategy is designed and applied to a WLFGD pilot plant taking into account the conclusions of a controllability analysis. The results reveal that good SO 2 control in WLFGD plants can be achieved mainly because the main disturbance of the process is well-aligned with the plant and interactions between control loops are beneficial to SO 2 control.
... AL Villanueva Perales*, P. Ollero, FJ Gutiérrez Ortiz and F. Vidal B. Departamento de Ingeni... more ... AL Villanueva Perales*, P. Ollero, FJ Gutiérrez Ortiz and F. Vidal B. Departamento de Ingeniería Química y Ambiental, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092, Seville, Spain. Ind. Eng. Chem. Res. ...
2Nd International Congress of Energy and Environment Engineering and Management, 2007
... Pedro Ollero a ... Equilibrium prediction is extended by incorporation some actions: (1) a ps... more ... Pedro Ollero a ... Equilibrium prediction is extended by incorporation some actions: (1) a pseudo-empirical prediction of the yields of char, tar and methane from the flaming pyrolysis processes and, (2) estimations of the unconverted fractions of these three components in the ...
In fluidized-bed gasification (FBG) of biomass and waste the temperature is maintained low enough... more In fluidized-bed gasification (FBG) of biomass and waste the temperature is maintained low enough to avoid agglomeration. This decreases carbon conversion and generates a tarry gas, reducing process efficiency and the gas utilization. In the present work optimization of FBG to achieve high char and tar conversion in the reactor is studied. Staged gasification is identified as a rational way to achieve the target with reasonable complexity and cost, so it is an ideal method for power production in small/medium biomass gasification plants. A recent development based on a tree-stage fluidized bed gasification system, is presented.
ABSTRACT In this work, two options are investigated to enhance the economics of the catalytic pro... more ABSTRACT In this work, two options are investigated to enhance the economics of the catalytic production of bioethanol from biomass gasification by exploiting the excess of CO2 emission saving: (i) to import fossil energy, in the form of natural gas and electricity or (ii) to trade CO2 emissions. To this end, an integrated life cycle and economic assessment is carried out for four process configurations, each using a different light hydrocarbon reforming technology: partial oxidation, steam methane reforming, tar reforming and autothermal reforming. The results show that for all process configurations the production of bioethanol and other alcohols significantly increases when natural gas displaces biomass, maintaining the total energy content of the feedstock. The economic advantage of the partial substitution of biomass by natural gas depends on their prices and this is explored by carrying out a sensitivity analysis, taking historical prices into account. It is also concluded that the trade of CO2 emissions is not cost-competitive compared to the import of natural gas if the CO2 emission price remains within historical European prices. The CO2 emission price would have to double or even quadruple the highest CO2 historical price for CO2 emission trading to be a cost-competitive option.
ABSTRACT Abstract In this study, a simplified methodology for the calculation of the balance of g... more ABSTRACT Abstract In this study, a simplified methodology for the calculation of the balance of greenhouse gas (GHG) emissions and corresponding saving compared with the fossil reference is presented. The proposed methodology allows the estimation of the anthropogenic GHG emissions of thermochemical biorefineries (net emitted to the atmosphere). In the calculation of the GHG balance, all relevant factors have been identified and analyzed including multiproduction, emissions from biogenic carbon capture and storage (Bio-CCS), co-feeding of fossil fuels (secondary feedstock) and possible carbon storage in biomass-derived products (chemicals). Therefore, it is possible to calculate the balance of GHG emissions of a hypothetical thermochemical biorefinery considering different alternatives of land-use, biomass feedstock, co-feeding of fossil fuels, Bio-CCS incorporation and final use of the products. The comparison of the estimated GHG balance with the corresponding fossil reference for each product is of special relevance in the methodology since it is the parameter used in European regulation for the fulfillment of sustainability criteria in biomass-derived fuels and liquids. The proposed methodology is tested using a previously assessed set of different process concepts of thermochemical biorefineries (techno-economic analysis). The resulting GHG balance and saving are analyzed to identify uncertainties and provide recommendations for future regulation. In all process concepts, the GHG savings are above the minimum requirement of GHG emissions for 2018. In the case of incorporating Bio-CCS, cradle-to-grave negative GHG emissions are obtained. However, in order to assess the role of chemical co-production from biomass, they need to be included in future regulation.
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Papers by Pedro Ollero