Hydrodynamics, Mass Transfer and Modeling of the Toluene Oxidation Process

The equilibrium solubility (C*), Critical mixing speed (NCRE) and (NCRI), Induced gas flow rate (QGI),volumetric liquid-side mass transfer coefficient (kLa), liquid-side mass transfer (kL), gas-liquid interfacial area (a), gas holdup (åG), Sauter mean bubble diameter (dS), and the bubble size distribution of N2, O2 and air in liquid toluene and three mixtures of toluene, benzaldehyde and benzoic acid, aimed at simulating the continuous liquid phase toluene oxidation (LPTO), were measured in a 4-liter ZipperClave surface aeration (SAR), gas inducing (GIR) and gas sparging (GSR) reactors operating under wide ranges of mixing speed (N) (800-1200 rpm), liquid height (H) (0.171-0.268 m in the SAR and GIR), superficial gas velocities (UG) (0.000-0.004 m/s in the GSR), temperature (T) (300-453 K) and pressure (P) (1-15 bar). These parameters were also measured in a 1-ft diameter, 10-ft high bubble column reactor (BCR) under various pressures (P) (2-8 bar), gas velocities (UG) (0.06-0.15 m/s).The solubility values of N2, O2 and air in liquid toluene and the three mixtures were calculated using a modified Peng-Robinson equation of state. (kLa) data were determined using the transient physical absorption technique. The bubble size distributions as well as the Sauter mean bubble diameters were obtained from the photographic method and the gas disengagement technique in the agitated reactors and bubble column reactor, respectively. In the agitated reactor, the gas holdup values were measured through the dispersion height measurement technique, and the manometric method using two differential pressure (dP) cells was employed in the bubble column reactor. From the gas holdup, Sauter mean bubble diameter and kLa experimental values, a and kL were calculated under various operating conditions. NCRE and NCRI as well as aWave were estimated by analyzing the videos taken with an on-line high-speed Phantom camera through the reactor's Jerguson windows. In the GIR, QGI was determined using a highly sensitive Coriolis mass flow meter. The Central Composite Statistical Design and analysis technique was used to study the effect of operating conditions on these hydrodynamic parameters.At constant temperature, the equilibrium solubilities (C*) of the three gases in all liquids used appeared to increase linearly with pressure and obey Henry's Law, however, the values exhibited minima with increasing temperature. The C* values were found to increase with increasing gas molecular weight, and decrease with the addition of benzaldehyde and benzoic acid to pure toluene. A dimensionless form of Arrhenius-type equation, in which the activation energy was dependent of temperature, was developed to predict Henry's law constant for the three gases in toluene and mixtures with a regression coefficient > 99%.In the SAR, increasing N, T or decreasing H increased aWave, åG, a, kL and kLa, and decreased dS and NCRE, whereas increasing P, decreased aWave, åG, a, kL and kLa and had no effect on dS and NCRE. In the GIR, increasing N or decreasing H increased QGI, åG, a, kL, kLa and dS and decreased NCRI. Also, increasing T increased and then decreased QGI, åG and a; increased kL and kLa; and decreased dS and NCRI. In addition, increasing P decreased slightly QGI and åG but did not affect a, kL, kLa, dS and NCRI under the operating conditions used. In the GSR, increasing N, T and UG increased åG, a, kL and kLa. Also, increasing N and T, or decreasing UG decreased dS. The addition of benzaldehyde and benzoic acid to pure toluene was found to significantly affect the hydrodynamic parameters (dS and åG), in the GSR and GIR, especially at low temperature due to formation of froth, which led to the enhancement of kLa. The hydrodynamic and mass transfer parameters obtained indicated that the behavior of the SAR was mainly dependent on kL, whereas those of the GSR and GIR were strongly affected not only by kL, but also by a. In the bubble column reactor, under the operating conditions used, kLa, a and åG values were found to increase with increasing gas superficial velocity and pressure, whereas dS and kL values appeared to decrease with pressure and increase with superficial gas velocity. The effect of gas nature on the hydrodynamic and mass transfer parameters was found to be insignificant, whereas the effect of addition of benzaldehyde and benzoic acid to pure toluene, aimed at mimicking the actual continuous liquid-phase toluene oxidation process, appeared to have a strong impact on both parameters due to froth formation.Empirical, statistical and Back-Propagation Neural Network (BPNN) correlations were also developed to predict the hydrodynamic and mass transfer parameters obtained in this study in the agitated reactors (ARs) and bubble column reactor (BCR) along with a large data bank of literature data (7374 data points in ARS and 3881 data points in BCRs). These correlations were then incorporated in calculation algorithms for predicting both hydrodynamic and mass transfer parameters in ARs and BCRs. Using these algorithms, two comprehensive models, including the effects of mass and heat transfer, hydrodynamics, and kinetics were developed for bubble column reactors (BCRs) and series of gas sparging reactors (GSRs) to simulate the commercial Liquid-Phase Toluene Oxidation (LPTO) process. An intrinsic kinetic rate equation for the toluene oxidation was also developed using literature data. The effects of the reactor diameter (DC), reactor height (H), and superficial gas velocity (UG) or mixing speed (N) on the LPTO process performances (toluene conversion, benzaldehyde selectivity and yield) were investigated in a BCR and a cascade of GSRs. The pressure and temperature at the inlet of the reactors were set at 1.0 MPa and 420 K; the feed gas to the reactors was a mixture (50/50 by mole) of oxygen and nitrogen; and the liquid feed was toluene containing Co catalyst and a NaBr promoter at concentrations of 0.22 wt% and 1.76 wt%, respectively. The heat of reaction was removed from both reactor types using water in cooling pipes, representing 2% of the reactor volume; and the gas was sparged into the reactors through a multi-orifices gas distributor with an open area, representing 10% of the reactor cross-sectional area. The model predictions showed that under the operating conditions used, toluene conversion of about 12%, a benzaldehyde selectivity of 40% and a benzaldehyde production in the range of about 1500 tons/year could be achieved using a superficial gas velocity of 0.1 m/s in the BCR (10-m height, 2-m Inside diameter) and 0.002 m/s in the series of 5 GSRs (2-m inside diameter, and 2-m liquid height). The BCR selected was found to operate in the kinetically-controlled regime whereas the 5-GSRs appeared to operate in a regime controlled by both gas-liquid mass transfer and reaction kinetics. Thus, due to its attractive economics in addition to the mechanical constraints of GSRs, the BCR seems to be the reactor of choice for the commercial-scale LPTO process

Drop impact in the regime of film boiling : transient evolution of the heat transfer and the vapor film thickness

International audienceWhen a drop impinges onto a wall heated above the Leidenfrost temperature, a very thin vapor film is formed at the interface between the liquid and the solid substrate. This vapor layer modifies the impact behavior of the drop and induces a significant decrease in heat transfer. To study this phenomenon, a model is proposed for the growth of the vapor film and the heat transfer at the impact. The main assumptions are: (i) a uniform but time varying thickness of the vapor film, (ii) a quasi-steady Poiseuille flow inside the vapor film, and (iii) a constant wall temperature. Heat energy and momentum balances are employed to obtain an ordinary differential equation describing the evolution of the vapor film thickness during the drop impact. Upon a one-dimensional analysis (nonetheless including some effects due to the complex fluid flow), the local heat flux transferred to the liquid qL can be evaluated. When the initial drop temperature is sufficiently lower than the saturation temperature, qL predominates over the heat flux used for liquid evaporation. This results in a simplified model for the vapor film thickness that we were able to validate against experiments carried out with ethanol droplets impacting an overheated sapphire surface (typically above 250°C). Two optical measurement techniques, based on laser-induced fluorescence imaging and infrared thermography, are associated to temporally and spatially characterize the heat transfer as well as the thickness of the vapor film

Application of an Analytical Scaling Method to Build Type Wells for Horizontal Wells in Resource Plays

The purpose of type wells is to portray the range of production profiles of a predetermined geological subset in a resource play. Most type well construction workflows rely on the creation of “average” profiles by simply averaging production for all wells in a given geological area, often a subset of a larger resource play. The production profile of empirical averaging cannot be directly associated with a set of reservoir and completion parameters. Relating to “Fetkovich’s Field Type Curve” methodology published in 1987, we show that we can create more representative type wells if we average the wells that are scaled to a common “base well” with known completion and reservoir parameters. Scaling factors are determined by a fit of production data to an analytical solution developed for horizontal wells exhibiting transient linear flow followed by boundary-dominated flow. The scaling factors are influenced largely by matrix permeability, fracture length, fracture spacing, drawdown and lateral length. We use the distribution of permeability and fracture half-length found in the type curve diagnostic to forecast undrilled wells and wells with only short production histories. Since the fit of production data depends on the geometrical shape of the type curve, we successfully demonstrate that the type curve applies to horizontal multi-fractured wells in known resource plays. We propose an original and integrated workflow based on our scaling methodology that includes the industry’s current best practices to create type wells and characterize a geologically similar area with publicly available data. Using this approach to scale production can dramatically increase the number of analogs and we demonstrate the application of the workflow with 126 wells from the Denton County in the Barnett shale. We observe that the scaling factors reduce the uncertainty of a typical well production for a given set of completion parameters, and provide a reliable tool to probabilistically forecast production. Furthermore, scaling time of underperforming wells in a group improves the durations of “known production” forecast. In conclusion, this analytically-based workflow provides reliable production forecasts and type wells with measured uncertainty. Because type wells are important tools for decision makers and engineers to determine economic feasibility of proposed development projects, more accurate type well construction has financial and strategic implications in the range of millions to billions of dollars

Comprehensive determination of the solid state stability of bethanechol chloride active pharmaceutical ingredient using combined analytical tools

International audienceThe use of an integrative analytical approach allowed us to establish the intrinsic solid state stability of bethanechol chloride (BC), an active pharmaceutical ingredient used in the treatment of urinary retention. First, the crystal structure of the monoclinic form has been described using single crystal X-ray diffraction studies. Second, thermal analyses revealed that the compound degrades upon melting, with an apparent melting temperature estimated to be 231 °C. No transition from the monoclinic to the orthorhombic form has been observed, suggesting that the monoclinic form is the stable one. Third, the two-step melting–decomposition process has been elucidated by liquid chromatography and thermogravimetry coupled to mass spectrometry. The first step corresponds to the sample liquefaction, which consists of the gradual dissolution of bethanechol chloride in its liquid degradant, i.e. betamethylcholine chloride. This step is in agreement with Bawn kinetics and the activation energy of the reaction has been estimated at 35.5 kcal mol−1. The second step occurs with accelerated degradation in the melt. Elucidation of secondary decomposition pathways evidenced autocatalytic properties conferred by the formation of both isocyanic acid and methyl chloride. Finally, dynamic water vapor sorption analysis showed a substantial hygroscopicity of the drug substance. A deliquescent point has been determined at 56% relative humidity at 25 °C

Mesure PLIF résolues dans le temps du champ de température à l'intérieur d'une goutte au cours de l'impact sur une paroi chaude

International audienceL’impact de gouttes sur des parois chaudes est rencontré dans de nombreux procédés, notamment le refroidissement par spray de surfaces solides à haute température. L’amélioration de ces procédés est souvent fastidieuse, en raison de la difficulté qu’il y a à modéliser, même pour une seule goutte, les phénomènes associés à un impact (en lien avec la thermique, l’hydrodynamique, l’ébullition). Dans les sprays, se rajoutent en plus des effets d’interaction entre les gouttes voisines. C’est pourquoi cette étude s’intéresse au cas d’une goutte isolée. Les transferts de chaleurs sont étudiés expérimentalement à l’aide d’une technique d’imagerie de fluorescence induite par laser qui permet de déterminer la température des gouttes. Les gouttes ensemencées par deux colorants fluorescents ayant des spectres d’émission décalés en longueur d’onde, ce qui permet de détecter séparément le signal de fluorescence qui leur est associé au moyen de deux caméras équipées de filtres chromatiques. Le champ de température du liquide est déterminé avec une bonne précision en effectuant le rapport des images obtenues par chaque caméra. Un des avantages décisifs de cette méthode est que ce rapport n’est pas perturbé par la déformation de la goutte au cours de l’impact. Les expériences sont effectuées dans le régime d’ébullition en film dans lequel une fine couche de vapeur se développe rapidement pendant l’impact à l’interface entre la goutte et la paroi solide. Ce film de vapeur empêche le contact direct entre le liquide et la surface solide, ce qui réduit considérablement les transferts de chaleurs. Les résultats montrent comment le champ de température évolue au sein de la goutte quand celle-ci impacte la paroi à différentes vitesses. Deux liquides, l’eau et l’éthanol, sont égale- ment considérés dans cette étude afin de mettre en évidence, l’effet des propriétés du liquide

Combined collision-induced dissociation and photo-selected reaction monitoring mass spectrometry modes for simultaneous analysis of coagulation factors and estrogens

AbstractOral estrogens are directly associated with changes in plasma levels of coagulation proteins. Thus, the detection of any variation in protein concentrations due to estrogen contraceptives, by a simultaneous analysis of both coagulation proteins and estrogens, would be a very informative tool. In the present study, the merit of photo-selected reaction monitoring (SRM), a new analytical tool, was evaluated towards estrogens detection in plasma. Then, SRM and photo-SRM detection modes were combined for the simultaneous analysis of estrogen molecules together with heparin co-factor and factor XIIa, two proteins involved in the coagulation cascade. This study shows that photo-SRM could open new multiplexed analytical routes

A Broadband Study of the Emission from the Composite Supernova Remnant MSH 11-62

MSH 11-62 (G291.1-0.9) is a composite supernova remnant for which radio and X-ray observations have identified the remnant shell as well as its central pulsar wind nebula. The observations suggest a relatively young system expanding into a low density region. Here we present a study of MSH 11-62 using observations with the Chandra, XMM-Newton, and Fermi observatories, along with radio observations from the Australia Telescope Compact Array (ATCA). We identify a compact X-ray source that appears to be the putative pulsar that powers the nebula, and show that the X-ray spectrum of the nebula bears the signature of synchrotron losses as particles diffuse into the outer nebula. Using data from the Fermi LAT, we identify gamma-ray emission originating from MSH 11-62. With density constraints from the new X-ray measurements of the remnant, we model the evolution of the composite system in order to constrain the properties of the underlying pulsar and the origin of the gamma-ray emission.Comment: 12 Pages, 12 figures. Accepted for publication in the Astrophysical Journa

Targeted proteomics links virulence factor expression with clinical severity in staphylococcal pneumonia

IntroductionThe bacterial pathogen Staphylococcus aureus harbors numerous virulence factors that impact infection severity. Beyond virulence gene presence or absence, the expression level of virulence proteins is known to vary across S. aureus lineages and isolates. However, the impact of expression level on severity is poorly understood due to the lack of high-throughput quantification methods of virulence proteins.MethodsWe present a targeted proteomic approach able to monitor 42 staphylococcal proteins in a single experiment. Using this approach, we compared the quantitative virulomes of 136 S. aureus isolates from a nationwide cohort of French patients with severe community-acquired staphylococcal pneumonia, all requiring intensive care. We used multivariable regression models adjusted for patient baseline health (Charlson comorbidity score) to identify the virulence factors whose in vitro expression level predicted pneumonia severity markers, namely leukopenia and hemoptysis, as well as patient survival.ResultsWe found that leukopenia was predicted by higher expression of HlgB, Nuc, and Tsst-1 and lower expression of BlaI and HlgC, while hemoptysis was predicted by higher expression of BlaZ and HlgB and lower expression of HlgC. Strikingly, mortality was independently predicted in a dose-dependent fashion by a single phage-encoded virulence factor, the Panton-Valentine leucocidin (PVL), both in logistic (OR 1.28; 95%CI[1.02;1.60]) and survival (HR 1.15; 95%CI[1.02;1.30]) regression models.DiscussionThese findings demonstrate that the in vitro expression level of virulence factors can be correlated with infection severity using targeted proteomics, a method that may be adapted to other bacterial pathogens

Bone Marrow Transplant

Mucopolysaccharidosis type I-H (MPS I-H) is a rare lysosomal storage disorder caused by α-L-Iduronidase deficiency. Early haematopoietic stem cell transplantation (HSCT) is the sole available therapeutic option to preserve neurocognitive functions. We report long-term follow-up (median 9 years, interquartile range 8-16.5) for 51 MPS I-H patients who underwent HSCT between 1986 and 2018 in France. 4 patients died from complications of HSCT and one from disease progression. Complete chimerism and normal α-L-Iduronidase activity were obtained in 84% and 71% of patients respectively. No difference of outcomes was observed between bone marrow and cord blood stem cell sources. All patients acquired independent walking and 91% and 78% acquired intelligible language or reading and writing. Intelligence Quotient evaluation (n = 23) showed that 69% had IQ ≥ 70 at last follow-up. 58% of patients had normal or remedial schooling and 62% of the 13 adults had good socio-professional insertion. Skeletal dysplasia as well as vision and hearing impairments progressed despite HSCT, with significant disability. These results provide a long-term assessment of HSCT efficacy in MPS I-H and could be useful in the evaluation of novel promising treatments such as gene therapy

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)