			Home About us Contact

Air Flow Rate (air + flow_rate)

Distribution by Scientific Domains

Chemistry	72%

Selected Abstracts

A pilot-scale demonstration of a membrane-based absorption- stripping process for removal and recovery of volatile organic compounds

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001
S. Majumdar
A new membrane-based continuous absorption-stripping process has been developed to separate gas/vapor mixtures, such as volatile organic compounds (VOCs), from a nitrogen/air stream. Two different hollow fiber membrane modules are needed in this process to remove the VOCs. In the first module, VOC-laden nitrogen/air stream flows through the bore of the hollow fibers. A suitable absorbent liquid with a high solubility for the VOC and essentially no solubility for nitrogen/air is pumped countercurrently over the outside of the fibers. This liquid is an inert, nontoxic, and essentially nonvolatile, organic solvent. The VOCs are effectively removed from nitrogen/air to a very low level and are concentrated in the absorbent for recovery, while the absorbent is regenerated by heating and subjecting it to vacuum in a separate hollow fiber membrane module called the stripping module. A pilot-scale membrane-based absorption-stripping unit was located next to a paint spray booth at Robins Air Force Base, Warner Robins, GA. Tests were performed on slip-streams of real-time air emissions from scheduled intermittent painting operations, so the concentration of VOC in the exhaust air fluctuated with time. The VOC removal efficiency was determined as a function of the feed air flow rate and the absorbent (silicone oil) flow rate. Depending on the gas/liquid flow rates and the inlet VOC concentration, the process successfully removed as much as 95+% of the VOC present. The experimental results have been compared with theoretical predictions. [source]

Influence of nitrogen on the degradation of toluene in a compost-based biofilter

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2001
Marie-Caroline Delhoménie
Abstract Two identical laboratory-scale bioreactors were operated simultaneously, each treating an input air flow rate of 1,m3,h,1. The biofilters consisted of multi-stage columns, each stage packed with a compost-based filtering material, which was not previously inoculated. The toluene inlet concentration was fixed at 1.5,g,m,3 of air. Apart from the necessary carbon, the elements nitrogen, phosphorus, sulfur, potassium and other micro-elements are also essential for microbial metabolism. These were distributed throughout the filter bed material by periodic ,irrigations' with various test nutrient solutions. The performance of each biofilter was quantified by determining its toluene removal efficiency, and elimination capacity. Nutrient solution nitrogen levels were varied from 0 to 6.0,g,dm,3, which led to elimination capacities of up to 50,g,m,3,h,1 being obtained for a toluene inlet load of 80,g,m,3,h,1. A theoretical analysis also confirmed that the optimum nitrogen solution concentration lays in the range 4.0,6.0,g,dm,3. Validation of the irrigation mode was achieved by watering each biofilter stage individually. Vertical stage-by-stage stratification of the biofilter performance was not detected, ie each filter bed section removed the same amount of pollutant, the elimination capacity per stage being about 16,g,m,3,h,1 per section of column. © 2001 Society of Chemical Industry [source]

A simple method to reduce the inspiratory oxygen fraction for high pulmonary blood flow patients in an operating room

PEDIATRIC ANESTHESIA, Issue 12 2007
AYAKO ASAKURA MD
Summary Background:, Low inspired oxygen acutely increases pulmonary vascular resistance and decreases pulmonary-systemic blood flow ratio. We present a simple method to lower inspired oxygen fraction (FIO2 < 0.21) without supplemental nitrogen, during mechanical ventilation by an anesthesia machine. Methods:, After institutional approval, seven healthy adult volunteers and three infants (0,12 month old) scheduled for congenital heart surgery were enrolled in this study. All the infants were diagnosed with congestive heart failure because of high pulmonary blood flow and were thought to benefit from low FIO2. The volunteers performed spontaneous ventilation (fresh air flow rate = 10 l·min,1, tidal volume = 600 ml, frequency = 10 br·min,1). The infants were mechanically ventilated with air (fresh air flow rate = 6 l·min,1, tidal volume = 10 ml·kg,1, 15 < frequency < 30 br·min,1 to adjust PaCO2 between 5.8 kPa and 6.5 kPa (45,50 mmHg), after induction of general anesthesia and tracheal intubation. The fresh gas flow rates were determined by the following formula. Fresh gas flow rate = (FIO2 , FEO2) EVE/(0.21 + FIO2 , FEO2 , target FIO2). We recorded FIO2 every 5 min for 30 min. When arterial oxygen saturation decreased >15%, fresh gas flow rates were increased to adjust FIO2 to 0.21. Results:, In all of the seven volunteers and three infants target FIO2 was achieved in <10 min. FIO2 was kept at 0.18 ± 0.01 (SD) by calculated fresh air flow rates. In one infant, SpO2 decreased >15% 20 min after lowering FIO2, we had to discontinue this study, and increase fresh gas flow to ventilate the infant with FIO2 0.21. In the other two infants, FIO2 was maintained throughout the study. Conclusions:, This simple and convenient method to decrease FIO2, has a utility in clinical situations, in which pulmonary vascular resistance is to be increased to improve systemic oxygen delivery in patients with high pulmonary blood flow during cardiac surgery. [source]

Effect of the Equipment Configuration and Operating Conditions on Process Performance and on Physical Characteristics of the Product During Coating in Spouted Bed

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2004
M. C. P. Publio
Abstract The effects of the configuration and operating conditions on the performance of the spouted bed tablet coating process have been studied. The configuration parameters analyzed were the ratio between the draft tube diameter and the inlet orifice diameter, dT/di, and the conical base angle, ,. To analyze the equipment performance the adhesion coefficient, ,, and the increase rate of the tablet mass, K1, were measured as a function of the mass flow rate of the coating material, Ws, of the ratio between the mass feed flow rate of coating suspension relative to mass feed flow rate of the spouting gas, W*s/W*g, of the air flow rate relative to minimum spouting, Q/Qms, and of the feed flow rate of atomising air, Wat. Procedures for the evaluation of the growth kinetics and for measuring the product uniformity are presented. On a étudié les effets de la configuration et des conditions opératoires sur la performance du procédé d'enrobage de tablettes en lit jaillissant. Les paramètres de configuration étudiés sont le rapport entre le diamètre du tube d'aspiration et le diamètre de l'orifice d'entrée, dT/di, et l'angle de base conique, ,. Pour analyser la performance de l'équipement, le coefficient d'adhésion, ,, et la vitesse d'augmentation du poids de la tablette, K1, ont été mesurés en fonction du débit massique du matériau d'enrobage, Ws, du rapport entre le débit d'alimentation massique de la suspension d'enrobage et le débit d'alimentation massique du gaz jaillissant, W*s/W*g, du débit d'air et du jaillissement minimal, Q/Qms, et du débit d'alimentation de l'air d'atomisation, Wat. On présente des méthodes pour évaluer les cinétiques de croissance et mesurer l'uniformité de produit. [source]

Effect of air flow rate on the foam fractionation of a mixture of egg white and egg yolk

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009
Chris C. Stowers
Abstract Foam fractionation was previously shown to be an effective tool for the separation of the two visible phases in a chicken egg: egg white and the egg yolk.1 This study is a continuation of the previous study with the objective of determining the optimal separation condition in terms of air flow rate. Our results show that air flow rate is a critical operational parameter when separating these protein-rich mixtures of egg white and egg yolk. The results show that respective concentrations of egg yolk and egg white phases change independently with respect to the air flow rate, leading to the observation that air flow rate could be exploited as a processing variable to selectively remove proteins from one section of the egg over the other section. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Study on Evaporating Characteristics of a Coaxial Two Impinging-Stream Concentrator

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2006
J. Yan
Abstract Based on the coaxial two impinging-streams principle, a new device for solution concentration was built and studied theoretically and experimentally. The experimental study focused on the effects of inlet air temperature, inlet air flow rate, and accelerating pipe length on the volumetric evaporative coefficient of the impinging-stream concentrator (ISC). The results show that the ISC has a relatively high volumetric evaporative coefficient, which increases with higher inlet air flow rates and higher inlet air temperature, and the ISC with a shorter accelerating pipe is more efficient. A theoretical model was suggested based on the consideration of mass, heat, and momentum transfers between liquid droplets and hot air. The concentration process of a sucrose solution in the ISC was simulated using the model and the results were compared with the experimental results, which indicated that the suggested model is reliable with a maximum relative error of less than 6.6,%. [source]

Effect of convective solar drying on colour, total phenols and radical scavenging activity of olive leaves (Olea europaea L.)

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009
Neila Bahloul
Summary In this study, olive leaves, which are known for their therapeutic and antioxidant properties, were used to assess the effect of solar drying conditions (temperature and flow rate) on the drying time and quality parameters of olive leaves. Samples were dried at three drying temperatures (40, 50 and 60 °C) and at two drying air flow rates (1.62 and 3.3 m3 min,1) in a convective laboratory solar dryer. From the experimental results, it was noted that the drying time required to reduce the moisture content to 0.10 kg kg,1 d.b. depends mainly on the drying temperature. The quality attributes of the dehydrated olive leaf samples were investigated in term of colour, total phenols and radical scavenging activity. The effect of solar drying on L*, a* b* parameters was significant (P < 0.05) for all the studied olive leaves. Besides, the total phenols of olive leaves were significantly (P < 0.05) influenced by drying air conditions and tended to decrease with increased drying time. The DPPH radical scavenging activity was higher in fresh [EC50 39.40 (ZR)-39.95 (CH)] than in dried leaves. However, the radical scavenging activity was also high in leaves dried at 60 °C, 3.3 m3 min,1 [EC50 54.21 (ZR),68.79 (CL)]. [source]

On the electrostatic equilibrium of granular flow in pneumatic conveying systems

AICHE JOURNAL, Issue 11 2006
Jun Yao
Abstract An analytical methodology involving the concept of "electrostatic equilibrium" is developed for granular flow in pneumatic conveying systems. The methodology can be used for estimation of the electrostatic field distribution at various sections of the system and explanation of the mechanisms involved for various electrostatic phenomena observed. For all cases conducted in the conveying system, there was a "charging time" required for the system to reach the state of "electrostatic equilibrium." Experiments conducted at different sections of the system showed that the time required increased in the order: horizontal pipe, vertical pipe, and pipe bend. Through a physical analysis, it is deduced that electrostatic equilibrium is related to the granules' behavior and local flow characteristics. In general, a longer time duration taken to reach equilibrium corresponds to a process with more complicated granular flow patterns. In the electrostatic equilibrium state, the field distribution shows the highest electrostatic field strength near the pipe wall, and this field strength degrades from the pipe wall to the pipe center. At various pipe sections, the highest strength occurs at the bend, in accord with observations that electric sparking first occurs at that location within the entire pneumatic conveying system. In the vertical pipe, granular distribution was measured using electrical capacitance tomography (ECT), and granular velocities were cross-referenced with those using particle image velocimetry (PIV). The electrostatic force at low air flow rates is found to be the primary cause for granules sticking to the pipe wall and results in the formation of the half-ring or ring structure. The state of electrostatic equilibrium is physically influenced by several elements in conveying systems. In a cyclic conveying system, a new pipe (or low humidity or no antistatic agent) tends to expedite the process to reach electrostatic equilibrium and attain high magnitude of electrostatic current at the state. In a non-cyclic horizontal conveying system, a thin film (pipe) is found to prolong the process duration to reach equilibrium, while the case with charged film (pipe) takes shorter duration to do so. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source]