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11.
建立了耐硫甲烷化循环式反应器的拟均相一维模型,考察了床层直径,循环比,入口气体温度及压力和温度范围对反应器操作的影响,结果表明:循环比和温度操作范围是反应器操作的决定因素,对日产5万标准立方煤气的反应器进行了优化设计分析。 相似文献
12.
Z. P. Lu L. Stachowicz P. Kong J. Heberlein E. Pfender 《Plasma Chemistry and Plasma Processing》1991,11(3):387-394
Diamond crystals and films have been success full y synthesized by DC thermal plasma jet CVD at a pressure of I atrn. A novel triple torch plasma reactor has been used to generate a convergent plasma volume to entrain the participating gases. Three coalescing plasma jets produces! by this reactor direct the dissociated and ionized gaseous species onto ( 100) silicon wafer substrates where the diamond grows. In a typical 10-min run, depending on the method of .substrate preparation, either microcrystals with sizes up to 8 m or continuous films with thicknesses of 1–2 m have been obtained. X-ray diffraction, scanning electron microscopy, and Raman spectroscopy have been used for the characterization of the crystals and of the films. 相似文献
13.
《Electroanalysis》2003,15(22):1782-1786
A generic approach to the design, construction and experimental characterization of novel microelectrochemical reactors (MECR) is presented. Structurally well‐defined rectangular microchannels incorporating electrochemical sensors were fabricated using a propriety photosensitive glass and photolithographic techniques. Microelectrode sensors were produced via evaporation to yield, gold, silver or platinum bands of approximate lengths 10–50 μm. The approach outlined permits cells of dimensions in the range: height 50–100 μm, width 100–500 μm and length 1–3 cm to be accurately constructed, in single or array configurations and were characterized via a voltammetric study utilizing electrolyte solutions containing N,N,N′N′‐Tetramethyl‐1,4‐phenylenediamine. In all cases, the test cells were constructed so that the three dimensional hydrodynamic boundary layer within the cells would significantly influence the reagent transport and therefore the observed current density at the microelectrodes. The current/flow rate relationship observed was analogous to the response of the observed within the macroscopic channel flow cells, where typically the cell design is restricted to configurations where a two dimensional transport analysis can be performed. 相似文献
14.
The effect of the biomass presence on the overall circulation velocity, the linear velocities both in the riser and the downcomer
and the overall gas hold-up was studied in a three-phase internal loop airlift reactor (ILALR). The measured data were compared
with those obtained using a two-phase system (air—water). All experiments were carried out in a 40 dm3 ILALR at six different biomass concentrations (ranging from 0 g dm−3 to 7.5 g dm−3), at a temperature of 30°C, under atmospheric pressure. Air and water were used as the gas and liquid model media, respectively.
Pellets of Aspergillus niger produced during the fermentation of glucose to gluconic acid in the ILALR were considered solid phase. In addition, liquid
velocities were measured during the fermentation of glucose to gluconic acid using Aspergillus niger. All measurements were performed in a bubble circulation regime. At given experimental conditions the effect of the biomass
on the circulation velocities in the ILALR was negligible. However, increasing of the biomass concentration led to lower values
of the total gas hold-up.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
15.
The effect of the shear rate on pullulan production from beet molasses by Aureobasidium pullulans P56 in an airlift reactor was investigated. A maximum polysaccharide concentration (18.5 g/L), biomass dry weight (14.0 g/L),
polysaccharide yield (38.5%), and sugar utilization (96%) was achieved at a shear rate of 42 s−1. A. pullulans grown on beet molasses produced a mixture of pullulan and other polysaccharides. The highest value of pullulan proportion
(30% of total polysaccharide) was obtained at a low shear rate (42 s−1). The apparent viscosity of the fermentation broth increased as the shear rate increased up to 42 s−1 and then decreased. On the other hand, the dissolved oxygen concentration and the volumetric mass transfer coefficient increased
with the increase of the shear rate from 21 to 84 s−1. The external addition of L-glutamic acid, olive oil, and Tween-80 improved significantly the production of crude polysaccharide (27.0 g/L), but the
pullulan content of the polysaccharide was low (20%). 相似文献
16.
Enhancing the enzymatic hydrolysis of cellulosic materials using simultaneous ball milling 总被引:1,自引:0,他引:1
Mais Ursula Esteghlalian Ali R. Saddler John N. Mansfield Shawn D. 《Applied biochemistry and biotechnology》2002,98(1-9):815-832
One of the limiting factors restricting the effective and efficient bioconversion of softwood-derived lignocellulosic residues
is the recalcitrance of the substrate following pretreatment. Consequently, the ensuing enzymatic process requires relatively
high enzyme loadings to produce monomeric carbohydrates that are readily fermentable by ethanologenic microorganisms. In an
attempt to circumvent the need for larger enzyme loadings, a simultaneous physical and enzymatic hydrolysis treatment was
evaluated. A ball-mill reactor was used as the digestion vessel, and the extent and rate of hydrolysis were monitored. Concurrently,
enzyme adsorption profiles and the rate of conversion during the course of hydrolysis were monitored. α-Cellulose, employed
as a model substrate, and SO2-impregnated steam-exploded Douglas-fir wood chips were assessed as the cellulosic substrates. The softwood-derived substrate
was further posttreated with water and hot alkaline hydrogen peroxide to remove >90% of the original lignin. Experiments at
different reaction conditions were evaluated, including substrate concentration, enzyme loading, reaction volumes, and number
of ball beads employed during mechanical milling. It was apparent that the best conditions for the enzymatic hydrolysis of
α-cellulose were attained using a higher number of beads, while the presence of air-liquid interface did not seem to affect
the rate of saccharification. Similarly, when employing the lignocellulosic substrate, up to 100% hydrolysis could be achieved
with a minimum enzyme loading (10 filter paper units/g of cellulose), at lower substrate concentrations and with a greater
number of reaction beads during milling. It was apparent that the combined strategy of simultaneous ball milling and enzymatic
hydrolysis could improve the rate of saccharification and/or reduce the enzyme loading required to attain total hydrolysis
of the carbohydrate moieties. 相似文献
17.
Eric Berson R. Mane Trupti V. Kurt Svihla C. Hanley Thomas R. 《Applied biochemistry and biotechnology》1998,(1):615-627
Variations to the original aeration system in a continuous roller bottle reactor of novel design have been tested and compared
for optimal oxygen (O) delivery. Reactor operating parameters that affect O transfer are rotation rate, liquid-volume level,
fresh-feed rate, and supplementary-aeration rate. Design modifications to enhance gas-liquid O transfer include the addition
of wall baffles and center baffles. The number and location of each of these baffles are compared for their effect on kLa values in the reaction chamber. The liquid feed into the system has been modified to improve the axial liquid mixing and
O transfer. 相似文献
18.
Xudong?Hu Gui-Bing?Zhao S.?V.?B.?Janardhan Garikipati Kim?Nicholas Stanislaw?F.?Legowski Maciej?RadoszEmail author 《Plasma Chemistry and Plasma Processing》2005,25(4):351-370
Laser-induced fluorescence (LIF) is an effective in-situ probe for NO concentrations below 300 ppm in a non-thermal plasma reactor. A new method has been developed to measure in-situ NO concentration in the reactor discharge region using a long-time—on the order of seconds—averaged fluorescence detection. This method, for quantifying NO concentration in a nonthermal plasma reactor, is simpler than a short-time—on the order of nanoseconds—fluorescence detection. For accurate measurement based on the new method, the LIF intensity must be close to the corona-induced fluorescence (CIF) intensity; the CIF intensity serves as a guide in selecting the LIF intensity. We find that a kinetic model proposed earlier works for two-tube reactors and represents the NO concentration in the middle of the reactor, which verifies the assumption of gas plug flow. 相似文献
19.
A flow system for the determination of d-glucose in undiluted whole blood, in which segmented sample injection and on-line dialysis are used to decrease the red cell volume fraction (haematrocrit) dependence, is described. Glucose is degraded enzymatically by means of immobilized glucose dehydrogenase. The nicotinamide coenzyme (NAD+) that is present in the solution is reduced in the enzymatic reaction and is reoxidized amperometically at 0 mV vs. Ag/AgCl on a graphite electrode, modified with phenoxazinium ion. The potential use of the system for clinical analysis is evaluated. 相似文献
20.
Stefan TsakovskiKarima Benkhedda Elisaveta IvanovaFreddy C Adams 《Analytica chimica acta》2002,453(1):143-154
8-Hydroxyquinoline (HQ), 2-methyl-8-hydroxyquinoline (CH3-HQ), 5,7-dichloro-2-methyl-8-hydroxyquinoline (Cl2-CH3-HQ), 5,7-dibromo-8-hydroxyquinoline (Br2-HQ), 5-sulfo-7-iodo-8-hydroxyquinoline (ferron) and 5-sulfo-8-hydroxyquinoline (SO3H-HQ) were compared as chelating reagents for on-line sorption preconcentration of cobalt in a knotted reactor (KR) precoated with the reagent. The results obtained with the different HQ derivatives reveal those properties of the chelating reagent responsible for the processes taking place in the KR. The influence of hydrophobicity, acidity, stability of the cobalt chelate and type of substituents in the HQ ring system on the separate steps of the flow injection (FI) preconcentration procedure are discussed. According to the performance characteristics of the different HQ derivatives, the most important parameters for on-line preconcentration in a KR are the hydrophobicity of the reagent and the stability of the chelate complex with the analyte. 相似文献