Search results for "residence time"
showing 9 items of 39 documents
Characterization and Evaluation of Hydrothermal Liquefaction Char from Alkali Lignin in Subcritical Temperatures.
2021
An evaluation of hydrothermal liquefaction (HTL) char is investigated in this work. Morphological studies, N2 adsorption behavior, FTIR analysis, thermal behavior, and elemental composition are studied. The HTL char yield showed an increase with higher operating temperatures. It increased from 11.02% to 33% when the temperature increased from 573 K to 623 K. At lower temperatures, the residence time showed an impact on the yield, while close to the critical point, residence time became less impactful. Elemental analysis showed that both higher operating temperatures and longer residence times increased the nitrogen content of the chars from 0.32% to 0.51%. FTIR analysis suggested the char b…
Physical Aspects of the Atmospheric Aerosol
1982
The atmospheric aerosol is a trace substance of the troposhere as well as the trace gases. Therefore a number of similiarities should be expected. As an example a common model on residence time is developed and discussed in its results. The residence time connects the content of a reservoir (size distribution for aerosols) with its source strength or removal rate. This is presented for the aerosol. In addition other physical properties of the tropospheric aerosol like optical, electrical and water uptake properties are discussed.
Inventory of the non‐native flora of Italy
2009
In this paper we present a comprehensive inventory of the non‐native vascular flora of Italy, which was produced within the project “A survey of the Italian non‐native flora”, funded by the Italian Ministry for the Environment. Previously published floristic accounts were the main source of information. Historical records were critically revised and integrated with recent literature, data from herbaria and some unpublished information, so as to obtain a complete, up‐to‐date catalogue of the non‐native vascular plant species that occur spontaneously in Italy. The inventory lists 1023 non‐native species and subspecies, which account for 13.4% of all the Italian flora. The Italian non‐native f…
Particle flow modelling in slurry-fed stirred vessels
2004
In this paper experimental information on the retention time distribution (RTD) of solid particles in a high-aspect-ratio vessel, stirred by three equally spaced Rushton turbines, is presented. The relevant data were obtained by a special technique named twin system approach (TSA) that greatly simpli+es the handling of particle-laden streams and is therefore particularly suited for investigating particle RTD in 9ow systems. The technique fundamentals are +rst summarized, together with the data analysis procedure. This lastly requires a numerical deconvolution operation that is easily performed with the help of Z-transforms. Two di;erent approaches for excluding the spurious contributions of…
Alien flora of Europe: Species diversity, temporal trends, geographical patterns and research needs
2008
International audience; The paper provides the first estimate of the composition and structure of alien plants occurring in the wild in the European continent, based on the results of the DAISIE project (2004–2008), funded by the 6th Framework Programme of the European Union and aimed at “creating an inventory of invasive species that threaten European terrestrial, freshwater and marine environments”. The plant section of the DAISIE database is based on national checklists from 48 European countries/regions and Israel; for many of them the data were compiled during the project and for some countries DAISIE collected the first comprehensive checklists of alien species, based on primary data …
Modeling small‐scale cassava starch extraction. Simulation of the reduction of water consumption through a recycling process
2010
International audience; The purpose of this study was to model the extraction unit operation of the cassava starch manufacturing process and to propose a realistic recycling simulation in order to reduce the volumes of effluents. The model was developed from reactors which are commonly used for cassava starch extraction at a household scale in Vietnam. The reactors were tested using inflow starch as a marker at the beginning of the batch process. The experimental residence time distribution (RTDexp) was calculated by the outflow of the starch concentration. Using Matlab®, the RTDexp was compared to the theoretical residence time distribution (RTDth). The dynamic model obtained was built up …
Polymeric scaffolds prepared via Thermally Induced Phase Separation (TIPS): Tuning of structure and morphology
2007
Scaffolds suitable for tissue engineering applications were prepared by Thermally Induced Phase Separation (TIPS) starting from a ternary solution PLLA/dioxane/water. The experimental protocol consisted of three consecutive steps, a first quench from the homogeneous solution to an appropriate demixing temperature (within the metastable region), a holding stage for a given residence time and a final quench from the demixing temperature to a low temperature (within the unstable region). A large variety of morphologies, in terms of average pore size and interconnection, were obtained upon modifying the demixing time and temperature, owing to the interplay of nucleation and growth processes dur…
Optimized Continuous Application of Hyperpolarized Xenon to Liquids
2018
International audience; In recent years, NMR with hyperpolarized (HP) xenon inside functionalized host structures (e.g. cryptophanes) have become a potential candidate for the direct observation of metabolic processes (i.e. molecular imaging). A critical issue for real applications is the dissolution of the HP-gas in the liquid which contains the host. In this work, we present recent developments for an improved and controlled dissolution of HP-Xe in liquids using hollow fiber membranes and different compressor systems. The designed apparatus consists of a compressor and a membrane unit. The compressor provides HP-129 Xe continuously at small adjustable pressures and in a polarization-prese…
Modeling biomass char gasification kinetics for improving prediction of carbon conversion in a fluidized bed gasifier
2014
Gasification of biomass in a fluidized bed (FB) was modeled based on kinetic data obtained from previously conducted thermo- gravimetic analysis. The thermogravimetric analysis experiments were designed to closely resemble conditions in a real FB gasifier by using high sample heating rates, in situ devolatilization and gas atmospheres of H 2 O / H 2 and CO 2 / CO mixtures. Several char kinetic models were evaluated based on their ability to predict char conversion based on the thermogravimetric data. A modified version of the random pore model was shown to provide good fitting of the char reactivity and suitability for use in a reactor model. An updated FB reactor model which incorporates t…