Search results for " reactor"
showing 10 items of 361 documents
Challenges in preparing for Environmental Technology Verification in a demonstration project: A case study of three innovative water treatment techno…
2022
The European Union's Environmental Technology Verification (ETV) program aims to foster innovative environmental technologies to reach the market and reassure potential users. This paper presents an investigation of using ETV for three technologies, being developed within the EU Zero Brine research and innovation project. The technologies were designed to recover high quality water, salts and minerals from brine solutions. The technologies in focus are the forward feed MED evaporator, the Multi Feed - Plug Flow Reactor Crystalliser and Eutectic Freeze Crystallization. The study sought to understand the challenges of the ETV process, the readiness and eligibility of technologies, and possibl…
Control of a non-isothermal continuous stirred tank reactor by a feedback–feedforward structure using type-2 fuzzy logic controllers
2011
A control system that uses type-2 fuzzy logic controllers (FLC) is proposed for the control of a non-isothermal continuous stirred tank reactor (CSTR), where a first order irreversible reaction occurs and that is characterized by the presence of bifurcations. Bifurcations due to parameter variations can bring the reactor to instability or create new working conditions which although stable are unacceptable. An extensive analysis of the uncontrolled CSTR dynamics was carried out and used for the choice of the control configuration and the development of controllers. In addition to a feedback controller, the introduction of a feedforward control loop was required to maintain effective control…
Power Consumption in Uncovered Unbaffled Stirred Tanks: Influence of the Viscosity and Flow Regime
2013
Notwithstanding the increasing industrial interest toward unbaffled tanks, available experimental information on their behavior is still scant, even for basic quantities such as the mechanical power drawn. In this work, the influence of the Reynolds and Froude numbers on the power consumption characteristics is presented for unbaffled stirred tanks operating both in nonaerated conditions (subcritical regime) and in aerated conditions (supercritical regime), i.e., when the free surface vortex has reached the impeller and the gas phase is ingested and dispersed inside the reactor. Experimental results obtained at various liquid viscosities show that power numbers obtained in subcritical condi…
On the simulation of stirred tank reactors via computational fluid dynamics
2000
Abstract Predictions of flow fields in a stirred tank reactor, obtained by computational fluid dynamics, were used for the simulation of a mixing sensitive process consisting of two parallel reactions competing for a common reagent: A + B → Prod .1 A + C → Prod .2. Experimental data were obtained for A = OH − , B = 1 2 Cu ++ and C=ethyl-chloroacetate. For this reaction scheme the final selectivity of the process, easily measured by a simple colorimetric analysis of the residual Cu++, was found to depend on agitation speed and therefore on the mixing history during the batch process. The flow field-based three-dimensional simulations performed here led to predictions that compared very well …
Measurements of Njs and Power Requirements in Unbaffled Bioslurry Reactors
2012
The remediation of urban/industrial polluted lands is a topic of crucial importance nowadays. Bioremediation techniques are widely employed to remove organic pollutants from contaminated soils because of their simplicity and cheapness. The bioslurry reactors mechanically agitated by stirrers represent one of the most promising bioremediation techniques. In the present work an unbaffled stirred vessel filled with solids and water is experimentally investigated from a fluid dynamic point of view. Air presence within the tank is guaranteed by the central vortex formation (typical occurrence concerning stirred vessels unprovided with baffles) instead of an intrinsically more expensive insufflat…
Power requirements for complete suspension and aeration in an unbaffled bioslurry reactor
2016
Remediation of contaminated soils is spreading as a matter of crucial importance nowadays. Bioremediation via bioslurry reactors of sites polluted by recalcitrant pollutants has been proved to be a valuable option, although optimization is needed to reduce process costs. Free-surface unbaffled stirred tanks (with central air vortex) have been recently proposed as a promising alternative to the more common systems provided with baffles. In a bioslurry reactor solid-liquid interfacial area, oxygen supply, solid loading per reactor unit volume should be maximized, and, at the same time, operation costs have to be kept low. In this regard, the minimum impeller speeds for complete suspension Njs…
Angle Stability Improvement by Switching Shunt Reactors in Mixed Overhead-Cable Lines
2010
Effect of pH on biological phosphorus uptake.
2006
An anaerobic aerobic laboratory scale sequencing batch reactor (SBR) was operated to study the effect of pH on enhanced biological phosphorus removal. Seven steady states were achieved under different operating conditions. In all of them, a slight variation in the pH value was observed during anaerobic phase. However, pH rose significantly during aerobic phase. The increase observed was due to phosphorus uptake and carbon dioxide stripping. When pH was higher than 8.2-8.25 the phosphorus uptake rate clearly decreased. The capability of Activated Sludge Model No. 2d (ASM2d) and Biological Nutrient Removal Model No. 1 (BNRM1) to simulate experimental results was evaluated. Both models success…
Analysis of the hydrodynamics of a periodically operated trickle-bed reactor—A shock wave velocity
2014
Abstract The relationship describing the shock wave velocity was formulated for the trickle-bed reactor operating at periodically changed feeding the bed with liquid phase. The values of shock wave velocity calculated from derived equations were compared with experimental values obtained for both fast and slow mode of base–pulse periodic liquid feeding and using liquids differing in physicochemical properties. A good agreement between these two sets of values of shock wave velocity was obtained. It has to be emphasized that the relationship (Eq. (26) ) derived in this study enables to estimate the values of the shock wave velocity when only mean values of variables of a process are known.
Effect of macro and micro nutrients addition during anaerobic mono-digestion of grass silage in leach-bed reactors
2019
The effect of macro- (NH4Cl) (set I) and micro-nutrients (Fe, Ni, Co and Mo) (set II) addition on chemical oxygen demand (COD) solubilisation during anaerobic mono-digestion of grass silage was investigated in two sets of leach bed reactor experiments at 35°C. Results showed that addition of NH4Cl and micro-nutrients improved COD solubilisation by 18% (0.56 g SCOD g−1 volatile solids) and 7% (0.45 g SCOD g−1 VS), respectively than control. About 20–50% of the added micro-nutrients were bioavailable in the produced leachates, while the rest (50–80%) were adsorbed onto the grass silage. Results of biological methane potential assays showed that, specific methane yields of grass silage were im…