Fouad Azizi

Hydrodynamics of liquid flow through screens and screen-type static mixers

An approach for predicting the spatial variation of the energy dissipation rate downstream of a screen is proposed in this article. It is based on extending the use of the homogeneous and isotropic turbulence decay equation to the very thin anisotropic region adjacent to the screen. Whereas the decay exponent and origin were kept constant in conformity with other previous investigations, the decay coefficient was slightly altered. This approach was found to be capable of predicting the experimental energy dissipation data obtained using liquid flow through screens and screen-type static mixers reasonably well over a wide range of design and operating conditions.

Pyrolysis of waste tires: A modeling and parameter estimation study using Aspen Plus®

This paper presents a simulation flowsheet model of a waste tire pyrolysis process with feed capacity of 150kg/h. A kinetic rate-based reaction model is formulated in a form implementable in the simulation package Aspen Plus, giving the flowsheet model the capability to predict more than 110 tire pyrolysis products as reported in experiments by Laresgoiti et al. (2004) and Williams (2013) for the oil and gas products respectively. The simulation model is successfully validated in two stages: firstly against experimental data from Olazar et al. (2008) by comparing the mass fractions for the oil products (gas, liquids (non-aromatics), aromatics, and tar) at temperatures of 425, 500, 550 and 610°C, and secondly against experimental results of main hydrocarbon products (C7 to C15) obtained by Laresgoiti et al. (2004) at temperatures of 400, 500, 600, and 700°C. The model was then used to analyze the effect of pyrolysis process temperature and showed that increased temperatures led to chain fractions from C10 and higher to decrease while smaller chains increased; this is attributed to the extensive cracking of the larger hydrocarbon chains at higher temperatures. The utility of the flowsheet model was highlighted through an energy analysis that targeted power efficiency of the process determined through production profiles of gasoline and diesel at various temperatures. This shows, through the summation of the net power gain from the plant for gasoline plus diesel that the maximum net power lies at the lower temperatures corresponding to minimum production of gasoline and maximum production of diesel. This simulation model can thus serve as a robust tool to respond to market conditions that dictate fuel demand and prices while at the same time identifying optimum process conditions (e.g. temperature) driven by process economics.

The effect of fast mixing conditions on the coagulation–flocculation process of highly turbid suspensions using liquid bittern coagulant

AbstractThe effect of fast mixing on floc formation and pollutant removal, using magnesium hydroxide as a coagulant, was investigated through characterization of relative strength and size of the formed flocs while operating at different mixing speeds and mixing times using a dynamic optical monitoring apparatus, and photometric dispersion analyzer (PDA2000). The parameters investigated included fast mixing speed (80, 100, and 120 rpm) and time (20, 40, and 60 s). Highly turbid kaolin clay suspensions (1213 ± 36 NTU) were alkalized using sodium hydroxide (NaOH) to pH values of 10.51 ± 0.02 at temperatures 20.7 ± 0.1°C, and liquid bittern (LB) was used as a coagulant. Fast mixing time had a clear effect on the flocs resistance to applied shear during the slow mixing phase. For all fast mixing times, 120 rpm caused the formation of largest flocs. Stronger flocs, indicated by the least change in flocculation index with time, required 60 s to form at all fast mixing speeds. Turbidity and TSS removal efficienc...

The use of the ensemble Kalman filter for production management in the presence of impermeable obstructions

This study presents a novel approach for maximizing the efficiency of the water flooding process by controlling the flood front dynamics. The optimization is carried out assuming the presence of spatially varying geological properties and impermeable obstructions located between the injection and production wells and thus hindering the sweep efficiency inside the reservoir. Controlling the flood front dynamics is achieved by coupling an ensemble Kalman filter scheme with a two-phase immiscible flow reservoir simulator and thus relying on a set of observational data provided via a grid of smart wells. For that purpose, a virtual grid of smart wells assumed to be fully saturated with water and evenly distributed around the obstruction location is employed. The presented method is applied to a synthetic numerical example where the fluid front is tracked to maximize water flooding by controlling the injection and production rates.