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11.
Zhen Jun WANG* Zheng Hua SONG Department of Chemistry Northwest University Xian 《中国化学快报》2003,14(3):283-286
Benzoicacidisacommonadditiveusedwidelyasfoodpreservativeandplasticizer.Itcouldpromoteseverereactiontoallergicpopulationevenatlowconcentrationlevel1.Routinemethodsfortheassayofbenzoicacidincludeschromatographic2-6,spectrophotometry7,8,capillaryelectrophoresis9-13andelectrochemicaltitration14.Stokes15etal.monitoredairbornebenzoicacidbasedonsurface-enhancedRamanscatteringtechniques.Thereisalsoreportonamicrobialsensorusingpseudomonasforbenzoicacidandtheirderivativesinaqua16.Interestofusinglumines… 相似文献
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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
16.
Pulverized coal plasma gasification 总被引:11,自引:0,他引:11
R. A. Kalinenko A. P. Kuznetsov A. A. Levitsky V. E. Messerle Yu. A. Mirokhin L. S. Polak Z. B. Sakipov A. B. Ustimenko 《Plasma Chemistry and Plasma Processing》1993,13(1):141-167
A number of experiments on the plasma-vapor gasification of brown coals of three types have been carried out using an experimental plant with an electric-arc reactor of the combined type. On the basis of the material and heat balances, process parameters have been obtained: the degree of carbon gasification (c), the level of sulfur conversion into the gas phase (s), the synthesis gas concentration (CO+Hz) in the gaseous products, and the specific power consumption for the gasification process. The degree of gasification was 90.5-95.0%, the concentration of the synthesis gas amounted to 84.7–85.7%, and the level of sulfur conversion into the gas phase was 94.3–96.7%. Numerical study of the process of plasma gasification of coals was carried out using a mathematical model of motion, heating, and gasification of polydisperse coal particles in an electric-arc reactor of the combined type with an internal heat source (arc). The initial conditions for a conjugate system of nonlinear differential equations of the gas dynamics and kinetics of a pulverized coal stream interacting with the electric arc and oxidizer (water vapor) agree with the initial conditions of the experiments. The computation results satisfactorily correlate with the experimental data. The mathematical model can be used for the determination of reagent residence time and geometrical dimensions of the plasma reactor for the gasification of coals.Nomenclature
c
i
volume concentration of components (kmol m–3)
-
x
longitudinal coordinate (m)
-
f
i
source members, determined by variation of the ith component due to chemical reactions in unit volume in unit time (kmol m–3s–1)
-
velocity (m s–1)
-
M
s
ash mass in one particle (kg)
-
C
D
particle drag coefficient
-
3.14
-
r
s
particle radius (m)
-
d
particle diameter (m)
-
density (kg m–3)
-
C
p
heat capacity of components (J molt– K–1)
-
Q
j
thermal effect of reaction (J kmol–1)
- Ej
activation energy of reaction
-
N
l
volume concentration of particles of thelth fraction (m–3)
-
T
temperature (K)
-
emissivity factor of coal particles
-
5.67 × 10–8, blackbody emissivity coefficient (W m–2 K–4)
-
P
pressure (Pa)
-
S
reactor cross section (m2)
-
D
reactor diameter (m)
-
V
reactor volume (m3)
-
L
R
reactor length (m)
-
F
W
friction force on the wall (N)
-
f
g
friction coefficient
-
residence time (s)
- Nu
Nusselt number
- Re
Reynolds number
- Pr
Prandtl number
-
thermal conductivity of gas (J m– s–1 K–1)
-
R
8.3 × 103, universal gas constant (J kmol K–1)
- µ
i
molecular mass of component (kg kmol–1)
-
dynamic viscosity coefficient of gas (kg m–1 s–1)
-
thermal efficiency of plasma reactor
- qarc
specific heat flow from arc (W m–3)
-
P
1
heat supplied in vapor at T = 405 K (W)
-
P
2
heat loss to wall (W)
-
P
3
heat loss in the gas and slag separator chamber (W)
-
P
4
heat loss in the synthesis gas oxidation chamber (W)
-
P
5
heat loss in the slag catcher (W)
-
P
6
heat carried away in the off-gas (W)
- P
heat input of arc (W)
-
P
arc
electric power of arc (W)
- Qsp
specific power consumption (kw Hr kg–1)
-
d
w
specific heat flow to wall (W m–2)
-
c
degree of carbon gasification (%)
-
s
level of sulfur conversion into gas phase (%) 相似文献
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18.
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
19.
《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
20.
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