Solid transport in a pyrolysis pilot-scale rotary kiln: preliminary results - stationary and dynamic results

4th International Conference on Conveying and Handling of Particulate Solids, Budapest, HUNGARY, MAY 27-30, 2003International audienceExperiments for the investigation of the flow of granular solids in a pyrolysis pilot-scale rotary kiln are presented. These experiments consisted first in measuring the volumetric filling ratio (steady-state experiences) for several operating conditions and second in recording the exit flow rates after a positive or negative step in one of the operating parameters (dynamic experiences). A dynamical model computing the evolution of the flow rate of granular solids through the kiln has been developed based on Saeman model [Chem. Eng. Prog. 47 (1951) 508]. The simulations are compared with experimental results; the model gives good results for the rolling mode, but for the slipping mode too

Optimization methodology for high COD nutrient-limited wastewaters treatment using BAS process

Optimization of biofilm activated sludge (BAS) process via mathematical modelling is an entangle activity since economic, environmental objective and technical decision must be considered. This paper presents a methodology to optimize the operational conditions of BAS process in four steps by combining dynamic simulation techniques with non-linear optimization methods and with operative decision-making criteria. Two set of variables are separately prioritized in the methodology: essential variables related to physical operation to enforce established process performance, and refinement variables related to biological processes that can generate risks of bulking, pin-point floc and rising sludge. The proposed optimization strategy is applied for the treatment of high COD wastewater under nutrient limitation using an integrated mathematical model for COD removal that include predation, hydrolysis and a simplified approach to the limiting solids flux theory in the secondary clarifier in order to facilitate the convergence of the optimization solver. The methodology is implemented in a full-scale wastewater treatment plant for a cellulose and viscose fibre mill obtaining (i) improvement of the effluent quality index (Kg pollution/m3) up to 62% and, (ii) decrease the operating cost index (€/m3) of the process up to 30% respect the regular working operational conditions of the plant. The proposed procedure can be also applied to other biological treatments treating high COD nutrient-limited industrial wastewater such as from textile and winery production among others

Energy efficiency in waste water treatments plants: Optimization of activated sludge process coupled with anaerobic digestion

This paper presents a study concerning the optimization of a Waste Water Treatment process. The process deals with carbon and nitrogen removal and includes activated sludge reactors coupled with an anaerobic digestion reactor. Nitrification and de-nitrification biochemical reactions are due to the biological activity of heterotrophic and autotrophic micro-organisms occurring inside the reactors. Rigorous Plant-Wide models that represent the main biochemical transformations have been constructed as per the CEIT approach [1]. The energy consumption for each Physical Unit Operation (P.U.O.) involved in the flow-sheet is evaluated and a full link is made between the biological activity and the electrical demand or production. Steady-state mathematical optimizations are then computed and the influence of primary settling efficiency on electrical autonomy is quantified and demonstrated. The ammonium recycling from digestion to activated sludge reactors is also demonstrated to be a limiting factor for the overall energy efficiency, as well as the C-substrate availability for denitrifying. Some conclusions are then drawn to improve the global electrical efficiency of the system. © 2011 Elsevier Ltd

Segregation affecting the evolution of primary recrystallization textures in a ternary Fe-Si-Sn alloy

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Combined effect of Pt and W alloying elements on Ni-silicide formation

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Calystegins, nutritional mediators in plant-microbe interactions

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