Residence time distribution in a biomass pretreatment reactor: Experimentation and modeling

Abstract

The production of cellulosic bioethanol, one of the two main possibilities of second generation biofuels, involves four dependent steps: pretreatment, enzymatic hydrolysis, fermentation and distillation. This work concerns the first step which purpose is to modify the structure of the lignocellulosic biomass hence allowing cellulose to become more accessible to enzymatic hydrolysis. In this paper, the biomass flow is characterized in a pretreatment reactor. This is done by performing residence time distribution (RTD) experiments along with the use of new methodology well adapted to our system, industrial pilot plant presenting tough thermodynamic conditions. In this novel methodology, the tracer, sodium carbonate, reacts with the acidified biomass. Our protocol consists in measuring the variation of electrical conductivity and pH at the reactor entrance and exit. Two experiments were performed in the reactor for two different theoretical residence times. A chemical model was developed allowing the determination of tracer concentrations from the measured data. The experimental residence time distributions in the reactor, obtained by deconvolution, are well represented by using CSTR and axial dispersion models. The obtained results point out the nearly plug-flow behaviour of the pretreatment reactor. 3/37

Design of a Horizontal Ball-Mill Reactor and Its Application in Dimerization of Natural Fatty Acids

“…The determination and analysis of material mixing process in a reactor is crucial to evaluate the performance of the reactor. The RTD represents the time a compound or fluid can spend inside a system, and the shape of RTD curve reflects the degree of backmixing, axial and radial diffusion of the compound or fluid, and therefore becomes a primary indicator of material mixing process on a macroscopic scale. , RTD can be experimentally determined by using inert tracers whose retention time corresponds generally to the retention characteristics of the compound or fluid. In this paper, the reactant, soybean fatty acid, was used as the compound or fluid, and methyl palmitate was used as tracer because of its similar fluidity to the fatty acids, which made the tracer closely follow the compound movement.…”

Hydrodynamics and parametric study of an activated sludge process using residence time distribution technique

“…The comprehensive performance of ASP can only be obtained by taking into account the biological treatment efficiency along with the hydraulic performance. The hydrodynamics of the reactor directly influences the biological treatment efficiency of the tank [4,9]. The intensity of mixing leads to enhanced mass exchange in the AT, hence directly influencing the concentration of residual polluting matter in the effluent.…”

“…Non-uniform flow in the ASP can result in anomalies like stagnant zones, bypassing, high recirculation rate, abnormal flow paths and inefficient mixing. Hydrodynamics of such intricate systems and processes can be examined using the residence time distribution (RTD) technique [7][8][9]. RTD is a well-established method that has been applied form many decades to study the hydrodynamics of complicated industrial systems [10][11][12][13].…”

A novel approach to residence time distribution characterization in a mAb continuous process

“…Due to the continuous addition and removal of material from the upstream and downstream process, continuous‐stirred tank reactor (CSTR) equations were utilized to model the RTD of molecules throughout the process (Fogler, 2006). This approach has been utilized extensively by pharmaceutical, oil, fertilizer, and polymer industries typically utilizing dyes, ions, or radioactive molecules for the tracer (Ben Abdelouahed et al, 2016; Bhaskar & Singh, 2018; Boskovic & Loebbecke, 2008; Orsi et al, 2009; Sharma et al, 2016; Sugiharto et al, 2009; Youssef et al, 2017). An alternative approach for RTD characterization of screw extruders utilized anthracene‐bearing substance as a fluorescent tracer demonstrating improved flow characteristics compared to radioactive and ion tracers (Hu et al, 1999).…”

“…Due to the continuous addition and removal of material from the upstream and downstream process, continuous-stirred tank reactor (CSTR) equations were utilized to model the RTD of molecules throughout the process (Fogler, 2006). This approach has been utilized extensively by pharmaceutical, oil, fertilizer, and polymer industries typically utilizing dyes, ions, or radioactive molecules for the tracer (Ben Abdelouahed et al, 2016;Bhaskar & Singh, 2018;Boskovic & Loebbecke, 2008;Orsi et al, 2009;Sharma et al, 2016;Sugiharto et al, 2009;Youssef et al, 2017). An alternative approach for RTD characterization of screw extruders utilized anthracenebearing substance as a fluorescent tracer demonstrating improved Nomenclature: C i , C 1 , C 2 , C 4 , C 6 , concentration of tracer at t = 0 (i) and at time t for bioreactor (1), permeate (2), pre-SPTFF hold tank (4), and post-SPTFF hold tank (6); C is , C i × % seiving for the post-bioreactor models including permeate, pre-SPTFF and post-SPTFF hold tanks for a tracer impacted by filter sieving; F, flowrate in and out of the bioreactor; t, time in hours; V, V2, bioreactor volume (V) and permeate volume in the ATF filter (2); τ, V/F; τs, (Tank volume × (1−PCV)/Volumetric flowrate)/% sieving.…”