A thermogravimetric and kinetic study on devolatization of woody biomass

Biomass is a promising energy resource for a more sustainable global energy outlook. Thermochemical conversion of biomass is a very attractive and important technology for energy generation and production of value-added products such as charcoal. With the aim of studying the internal processes taking place when thermochemical conversion of biomass takes place, in this Master’s Thesis a thermogravimetric analysis of woody biomass samples was developed. Woody biomass samples underwent pyrolysis experiments, with the main goal of the development of the kinetic modeling and simulation of the decomposition process. Also, the effect of various experimental parameters was studied for achieving increasing char yield values in pyrolysis processes. Pyrolysis experiments of hardwood (birch and oak) and softwood (spruce) samples were developed by means of a thermogravimetric analyzer. Besides, two types of samples were studied for each of the mentioned species: stem wood samples and forest residue samples, composed by tops and branches of the trees (named as GROT, the corresponding Norwegian acronym). By means of changing particle size and sample mass of the samples, it was analyzed whether this parameters affected the kinetics of the samples and so, whether reactions were fully kinetically controlled or some heat and mass transfer limitations were needed to be considered. For this, three different kinetic approaches were employed. From the results obtained, it was concluded that the considered experimental parameters had some effects on the kinetics of the samples, as not negligible differences were registered in the values of the kinetic parameters obtained under different experimental conditions. Besides, the heterogeneous nature of GROT samples was also proved in terms of kinetics, in contrast with the high level of repeatability of the stem wood samples. Regarding the study of the char yield, it was concluded that higher char yield values were obtained when developing the pyrolysis experiments in an atmosphere of generated volatiles, rather than in a pure, nitrogen atmosphere. The effect of ash forming elements favoring char yield was also observed, with GROT samples giving the highest values. It was also registered an odd behavior of oak stem wood and GROT samples, which is further explained in this Thesis.

Planta de generación de energía eléctrica de 5MWe mediante lodos de EDAR

[ES]Este proyecto pretende plantear una solución viable y que, por tanto, resulte económicamente rentable, para la gestión de los lodos de depuradora generados en una estación de tratamiento de aguas residuales. Así, este documento se centrará, por una parte, en realizar un acercamiento al mundo de la depuración de aguas residuales y en estudiar los distintos procesos y tratamientos que se llevan a cabo en una depuradora, y por otra, planteará la valorización energética de los lodos mediante su combustión en una planta de generación de energía eléctrica como la solución al problema de gestión que suponen, no sin antes haber valorado las distintas alternativas posibles en cuanto a la salida que se les podría dar a estos fangos. De esta forma, la base del proyecto, una vez se haya optado por la alternativa de la valorización energética como la opción a desarrollar, consistirá en plantear los principios y fundamentos necesarios para el diseño de la planta de generación de energía eléctrica mediante lodos de depuradora que se pretenderá instalar. Se realizará, por tanto, una descripción de la planta generadora de electricidad detallándose el proceso que se llevará a cabo en la misma. Asimismo, se realizará el dimensionamiento de los diferentes equipos que tomarán parte en dicho proceso. Para finalizar, se planteará el estudio económico y de rentabilidad del proyecto que constituirá la creación de una planta de generación eléctrica mediante lodos, con el fin de comprobar el grado de viabilidad del mismo, y se analizarán los posibles riesgos a los que puede exponerse un proyecto de este tipo.[EU]Proiektu honen helburua uren tratamendurako estazio batean sortutako araztegi-lohien kudeaketak suposatzen duen arazoari bideragarria eta ekonomikoki errentagarria izan daitekeen soluzioa planteatzea da, hain zuzen ere. Horretarako, lehenik eta behin uren arazketaren mundurako gerturatzea burutuko da, araztegi batean ematen diren prozesu eta tratamendu ezberdinen deskripzioa eginez eta hauen nondik norakoak azalduz, eta jarraian lohien gestioak ekartzen dituen arazoei erantzun emateko modutzat, konbustioan oinarritutako lokatzen balioztapen energetikoa planteatuko da energia elektrikoko planta batean. Lohientzat erabilera hau erabaki aurretik, posible liratekeen beste zenbait aukera planteatu eta aztertuko dira, guztien artean irteera egoki bezala konbustioan oinarritutako prozedura hautatuko delarik. Behin aukera guztiak baloratuta eta lohiei emango zaien irteera adostuta, proiektuaren muina garatuko da: hain zuzen ere, instalatu nahiko den lohien bidezko energia elektrikoko plantaren diseinurako oinarriak finkatuko dira, hots, plantan bertan burutuko diren prozesuen deskribapena egingo da, bai eta prozesu horietan parte hartuko duten ekipo ezberdinen deskripzioa eta dimentsionaketa egin ere. Amaitzeko, araztegiko lohiez hornituko den planta elektrikoaren proiektuaren azterketa ekonomikoa garatuko da, bere errentagarritasuna aztertuko delarik; honen bidez, proiektuaren bideragarritasuna frogatzea bilatzen da, hain zuzen, proiektuaren zertzearen bideragarritasuna. Honekin batera, honelako proiektu batek izan ditzakeen arriskuak eta hauek gertatzeko probabilitate-maila baloratuko dira.[EN]By means of this project, a viable and profitable solution is pursued regarding the management of the sludge produced in a wastewater purifying plant. Firstly, this document will approach and introduce the wide world of wastewater depuration and will study the processes and treatments carried out in purifying plants. Once the depuration field is introduced, the energy recovery by combustion of the sludge produced in the wastewater treatment plant will be considered, in response to the waste management problem. Of course, some other solutions and alternatives will be considered related to the end use of the sludge, among which the choice of the combustion and subsequent energy recovery will be selected. Therefore, and after having made the decision about the final use of sludge, the basis of the project will be developed: the description and measuring of the main equipment that participates in the different processes that will be developed in the electricity generation plant, which will conform the main design of the facilities. Finally, an economic study will be carried out, so as to evaluate the profitability of the project itself and the viability of it. In addition, the risks that the execution of the project could involve will be brought up, so that measures that take those risks into account can be taken

A thermogravimetric and kinetic study on devolatization of woody biomass

Biomass is a promising energy resource for a more sustainable global energy outlook. Thermochemical conversion of biomass is a very attractive and important technology for energy generation and production of value-added products such as charcoal. With the aim of studying the internal processes taking place when thermochemical conversion of biomass takes place, in this Master’s Thesis a thermogravimetric analysis of woody biomass samples was developed. Woody biomass samples underwent pyrolysis experiments, with the main goal of the development of the kinetic modeling and simulation of the decomposition process. Also, the effect of various experimental parameters was studied for achieving increasing char yield values in pyrolysis processes. Pyrolysis experiments of hardwood (birch and oak) and softwood (spruce) samples were developed by means of a thermogravimetric analyzer. Besides, two types of samples were studied for each of the mentioned species: stem wood samples and forest residue samples, composed by tops and branches of the trees (named as GROT, the corresponding Norwegian acronym). By means of changing particle size and sample mass of the samples, it was analyzed whether this parameters affected the kinetics of the samples and so, whether reactions were fully kinetically controlled or some heat and mass transfer limitations were needed to be considered. For this, three different kinetic approaches were employed. From the results obtained, it was concluded that the considered experimental parameters had some effects on the kinetics of the samples, as not negligible differences were registered in the values of the kinetic parameters obtained under different experimental conditions. Besides, the heterogeneous nature of GROT samples was also proved in terms of kinetics, in contrast with the high level of repeatability of the stem wood samples. Regarding the study of the char yield, it was concluded that higher char yield values were obtained when developing the pyrolysis experiments in an atmosphere of generated volatiles, rather than in a pure, nitrogen atmosphere. The effect of ash forming elements favoring char yield was also observed, with GROT samples giving the highest values. It was also registered an odd behavior of oak stem wood and GROT samples, which is further explained in this Thesis.

Contemporary use of cefazolin for MSSA infective endocarditis: analysis of a national prospective cohort

Objectives: This study aimed to assess the real use of cefazolin for methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis (IE) in the Spanish National Endocarditis Database (GAMES) and to compare it with antistaphylococcal penicillin (ASP). Methods: Prospective cohort study with retrospective analysis of a cohort of MSSA IE treated with cloxacillin and/or cefazolin. Outcomes assessed were relapse; intra-hospital, overall, and endocarditis-related mortality; and adverse events. Risk of renal toxicity with each treatment was evaluated separately. Results: We included 631 IE episodes caused by MSSA treated with cloxacillin and/or cefazolin. Antibiotic treatment was cloxacillin, cefazolin, or both in 537 (85%), 57 (9%), and 37 (6%) episodes, respectively. Patients treated with cefazolin had significantly higher rates of comorbidities (median Charlson Index 7, P <0.01) and previous renal failure (57.9%, P <0.01). Patients treated with cloxacillin presented higher rates of septic shock (25%, P = 0.033) and new-onset or worsening renal failure (47.3%, P = 0.024) with significantly higher rates of in-hospital mortality (38.5%, P = 0.017). One-year IE-related mortality and rate of relapses were similar between treatment groups. None of the treatments were identified as risk or protective factors. Conclusion: Our results suggest that cefazolin is a valuable option for the treatment of MSSA IE, without differences in 1-year mortality or relapses compared with cloxacillin, and might be considered equally effective