Solid-fluid mixing behavior of conical spouted beds with internal devices

The effect of draft tubes and fountain confiner on the gas and solids mixing behavior is studied in conical spouted beds. Accordingly, the bed porosity has been determined in different hydrodynamic regimes of 1:1; 1:25 and 1:5 u=ums , with beds equipped with draft tubes of 0%; 56% and 100% opening ratio. These devices significantly affect the gas residence time and particle cycle time distributions, which are further improved by using a fountain confiner, specially when high inlet gas flow rates are desired. The addition of this device was found to remove stagnant gas pockets over the annular zone, while reducing the par- ticle cycle time by 15% with the OSDT configuration at 1:5 u=u ms . This reduction heavily depends on the distance between the bed surface and the fountain confiner. By including draft tubes, the expected par- ticle cycle time can be more than doubled due to the reduced annular-spot solids circulation. Therefore, it was found that a combination of internal devices and operating flow rate present a promising strategy to control the gas flow pattern, while keeping the distribution of particles cycle times required for each application.This work has been carried out with the financial support from the Spain’s Ministries of Economy and Competitiveness (CTQ2016- 75535-RðAEI=FEDER; UEÞ) and Science and Innovation (PDI2019-107357RB-I00ðAEI=FEDER; UEÞ), the Basque Government (IT218-19) and the University of the Basque Country UPV/EHU (US16/21). Aitor Atxutegi is grateful for his Ph.D. grant from the University of the Basque Country UPV/EHU(PFI15-2017)

Factores de riesgo y supervivencia libre de tumor en pacientes con trasplante renal de cadáver

[Background] There is an agreement in the fact that cancer incidence in transplant recipients increases at a rate disproportionately greater than in the general population. Several clinical studies have identified cancer risk factors, such as age, male gender, tobacco, UV radiation, viral infections, previous malignancies, intensity and duration of immunosuppressive therapies, HLA matches and time in waiting list.

The Knowledge Management Processes at Different Stages of Group Development

ABSTRACT Based on a developmental approach, this study intended to analyze the extent to which the different stages of group development differ regarding the use of knowledge management processes. The sample comprised 211 teams belonging to a Portuguese military organization. In order to test the hypotheses a multivariate analysis of variance was conducted. The results showed that more mature and cooperative groups (Restructuring/Realization phase) apply to a greater degree the processes of knowledge management, while groups in which there is high intragroup competition and in which members try to “gain power” among themselves (Reframing phase), apply these processes to a lesser degree

Postcombustion CO2 capture with CaO. Status of the technology and next steps towards large scale demonstration

10th International Conference on Greenhouse Gas Control Technologies[EN] Postcombustion CO2 capture using CaO requires a large scale circulating fluidized bed (CFB) reactor as CO2 absorber, operating between 600-700ºC. In addition, a large scale oxy-fired CFBC must be interconnected to this reactor to allow for the decomposition of CaCO3 formed in the carbonator. This allows for a continuous regeneration of the CaO sorbent and the production of a CO2 rich stream suitable for final purification and compression. Despite the known limitations associated to this technology (mainly sorbent deactivation, solid attrition, and high energy requirements in the calciner) clear operating windows have been identified at which the process could be implemented in practice using the know-how on CFBC technology. Theoretical studies on the thermal integration of a carbonation-calcination loop in new and existing power plants have shown that the technology has the potential to achieve a substantial reduction (around 30%) in capture cost and energy penalties with respect to stand-alone oxy-fired systems. Since the solid materials and operating conditions in the CFB units are similar to those present in existing large scale CFBCs, the prospects for a rapid scaling up of the technology are very promising. A rapid development is taking place in recent years by demonstrating the key concepts in laboratory scale test rigs of 10s of kW. However, it is essential to move on to the next phase of pilot testing and validate the results in conditions fully comparable with those expected in large scale units. We describe here the design of a 1 MWth pilot plant to capture 70-95% of the CO2 contained in the flue gas from a 1/150 side stream emitted by an existing 50MWe CFB power plant. The pilot is made up of two interconnected CFB reactors of 15 m height. The construction of the pilot has been initiated and is expected to enter into full operation in the first half of 2011, providing the necessary experimental results to decide on the launching of an aggressive development programme that aims to demonstrate the technology at large scale well before 2020.This work is being funded by the European Commission 7th Framework Programme under the CaOling project.Peer reviewe

An Assessment of the Impact of Social Networks on Collaborative Learning at College Level

This study considers the effect of the usage of a social network site (www.grouply.com) for a class related group project on the development of individual abilities and performance in group work. Data were collected from three sections of an intermediate macroeconomic class at a Spanish university and groups were randomly assigned to work (or not) using the social network. Findings suggest that, although students are in general attracted by the idea of using SNS in class-related team work, the introduction of a tool they are not familiar with may hamper their self-perceived level of competence in a number of skills

An Assessment of the Impact of Social Networks on Collaborative Learning at College Level

This study considers the effect of the usage of a social network site (www.grouply.com) for a class related group project on the development of individual abilities and performance in group work. Data were collected from three sections of an intermediate macroeconomic class at a Spanish university and groups were randomly assigned to work (or not) using the social network. Findings suggest that, although students are in general attracted by the idea of using SNS in class-related team work, the introduction of a tool they are not familiar with may hamper their self-perceived level of competence in a number of skills

Microstructure and Pb2+ Adsorption Properties of Blast Furnace Slag and Fly Ash based Geopolymers

In this study, a blast furnace slag (BFS) and fly ash (FA) based adsorbent geopolymer to be used for removing Pb2+ from aqueous solutions were synthesized using the hydrothermal method at 60 °C for 24 h, and then cured at 25 °C for another six days. The alkali activator applied in this work was a combination of sodium hydroxide and sodium silicate solutions at a mass ratio of 2. The geopolymer slurry was adjusted to a Si/Al molar ratio of 3. A BFS-based geopolymer (GS) having a specific area of 23.56 m2/g and pore size and volume of 7.8 nm and 73 cm3/kg, respectively, surpassed the raw material surface by approximately 13-fold. An FA-based geopolymer (GA) having a specific area of 35.97 m2/g and a size and porous volume of 9 nm and 124 nm, respectively, surpassed the raw material surface by approximately 23-fold. In addition, GS and GA showed a cation exchange capacity (CEC) of 241.30 and 286.96 Meq/100 g, respectively. X-ray diffraction (XRD) determined sample crystallinity and it was proven by scanning electron microscopy (SEM), showing that both geopolymers were constituted of unreacted particles surrounded by amorphous and semi-amorphous products. Through Fourier transform infrared spectroscopy (FTIR), a band that was assigned to the asymmetric stretching vibration of Si-O-M (M = Na+ and/or Ca2+) non-bridging oxygen type was observed, which suggested that Na and Ca could serve as exchangeable ions in the ionic exchange process. Adsorption test data indicated that good adsorption was obtained when a neutral pH was used at room temperature, and the adsorption isotherm showed that GA had more adsorption sites than GS, which meant greater maximum adsorption capacity