Search results for "fixed bed"

Comparing flow resistance law for fixed and mobile bed rills

2019

Rills caused by run-off concentration on erodible hillslopes have very irregular profiles and cross-section shapes. Rill erosion directly depends on the hydraulics of flow in the rills, which may differ greatly from hydraulics of flow in larger and regular channels. In this paper, a recently theoretically deduced rill flow resistance equation, based on a power–velocity profile, was tested experimentally on plots of varying slopes (ranging from 9% to 26%) in which mobile and fixed bed rills were incised. Initially, measurements of flow velocity, water depth, cross-section area, wetted perimeter, and bed slope, carried out in 320 reaches of mobile bed rills and in 165 reaches of fixed rills, …

Rill flow resistance law under sediment transport

2021

Abstract Purpose In this paper, a deduced flow resistance equation for open-channel flow was tested using measurements carried out in mobile bed rills with sediment-laden flows and fixed bed rills. The main aims were to (i) assess the effect of sediment transport on rill flow resistance, and (ii) test the slope-flow velocity relationship in fixed bed rills. Methods The following analysis was developed: (i) a relationship between the Γ function of the velocity profile, the rill slope and the Froude number was calibrated using measurements carried out on fixed bed rills; (ii) the component of Darcy-Weisbach friction factor due to sediment transport was deduced using the corresponding measurem…

Slope threshold in rill flow resistance

2022

The applicability of a theoretical rill flow resistance equation, based on the integration of a power velocity distribution, was tested using measurements carried out in mobile and fixed bed rills, shaped on plots having different slopes (9, 14, 15, 18, 22, 24, 25 and 26%) and soil textures (clay fractions ranging from 32.7% to 73% and silt of 19.9–30.9%), and flume measurements available in the literature. The Darcy–Weisbach friction factor resulted dependent on the slope, Froude number, Reynolds number and clay and silt percentages, used as variables representative of soil transportability and detachability, respectively. This theoretical approach was applied to two different databases di…

Hydrodynamics of a three-phase fixed-bed reactor operating in the pulsing flow regime at an elevated pressure

2002

Abstract Results are presented for a three-phase reactor operating at an elevated pressure in the pulsing flow regime. For the system air–water and pressures of 0.1– 0.9 MPa lines are determined that define the change of the hydrodynamic model from the gas continuous flow regime (GCF) to the pulsing flow regime (PF). Also, parameters are found that characterize the pulsing flow of fluids, namely the velocity of pulses travelling along the bed, the frequency of pulsations and their structure, i.e., the length of the pulses and that of the liquid-rich zone.

Hydrodynamics of a Pressurised Three-phase Fixed-Bed Reactor, Operating in the Pulsing Flow Regime

2001

A Novel Lab‐Scale Fixed‐Bed Pyrolysis Reactor for Biofuel Production from Agro‐Waste: Experimental Set‐up and Preliminary Life Cycle Assessment Study

2020

The present study reports the features and set-up of a novel lab-scale fixed bed pyrolysis reactor for the production of solid and liquid bio-fuels from waste biomass. The fixed bed reactor is tested by carrying out pyrolysis experiments using two different waste biomasses. Olive tree trimmings (OT) and olive pulp (OP), olive cultivation and olive mill industries residues respectively, are pyrolyzed, under nitrogen atmosphere, between 200 and 650 °C for a residence time of 0.5 h. The OT and OP pyrolysis chars were characterized in terms of mass yields, high calorific values (HHVs), proximate and elemental analysis. Char mass yields, on a dry basis (d.b.), decreased from 91 to 23 wt% and fro…

Photocatalytic oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde in a fixed bed continuous reactor,

2008

Modeling of the effect of EDTA on copper(II) biosorption onto Posidonia oceanica waste in batch and fixed-bed systems

2014

Abstract The performance of Posidonia oceanica for copper(II) biosorption in the presence of EDTA was investigated in batch and column experiments. In batch mode, copper(II) uptake in the presence of EDTA was lower than in its absence for the pH range 1.5–6.0. The decrease in the copper(II) uptake, attributed to the change in the chemical speciation of copper(II) with EDTA in solution, was from 71.7 to 58.8 mg/g in the absence and presence of EDTA respectively at pH 6. Column experiments were carried out at 5 and 20 mg Cu(II)/dm 3 and different doses of EDTA. Constant copper(II) leaks were detected in the effluent of the columns. Leak concentrations matched the copper(II)-EDTA complexes’ co…

Kinetics of 4-Methoxybenzyl Alcohol Oxidation in Aqueous Solution in a Fixed Bed Photocatalytic Reactor

2010

WOS: 000280384800004