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151.
威海市污水处理深海排放工程是为改善其水域环境而建设的一英包括市区排水系统,污水预处理厂,输水管道和海洋放流管系统在内的完整而典型的工程,因此其工程设计扣的经验将会对同类项目的设计与工程建设有所借鉴。 相似文献
152.
153.
Certain new sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for
which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that
is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation
to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and
calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, calcium
sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce calcium sulfide, which is used to reduce sulfur
dioxide to elemental sulfur vapor and calcium sulfate. The latter is, in turn, reduced to regenerate calcium sulfide. In this
Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and calcium-sulfide
pellets, which produces elemental sulfur and calcium sulfate. The experiments were carried out at temperatures between 1023
and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique.
The rate of this reaction was demonstrated by the conversion of 40 pct calcium-sulfide pellets obtained from the hydrogen
reduction of fresh calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity
decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic
of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants.
A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial
pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for calcium-sulfide pellets reacted and regenerated
several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification,
combined-cycle, desulfurization unit and new sulfide-smelting plants, contain much higher partial pressures of SO2. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported
in this article. The reduction kinetics of calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part
II. 相似文献
154.
155.
Microbiological denitrification of red beet juice 总被引:1,自引:0,他引:1
Dorota Walkowiak-Tomczak 《European Food Research and Technology》2002,215(5):401-406
The purpose of study was the determination of optimal conditions for red beet juice denitrification by Paracoccus denitrificans bacteria as well as the evaluation of the usefulness of microbiologically treated juice for the production of a natural colouring preparation for foods. Total reduction of nitrates was found during bacterial culturing at 25 and 30 °C, at an initial pH of 7.0-8.0 and juice osmotic pressure of 900-1100 mOsm/kg. Microbiological denitrification procedure affected colour, taste and aroma of the juice. However, the use of juice as food colouring and component was made feasible by acidification and partial evaporation of water together with volatile substances. 相似文献
156.
Jin-Wei Shi Chi-Kuang Sun 《Lightwave Technology, Journal of》2002,20(11):1942-1950
We present the theory and design of a tapered line distributed photodetector (TLDP). In the previously demonstrated velocity-matched distributed photodetector (VMDP), high electrical bandwidth is achieved by proper termination in the input end to absorb reverse traveling waves, sacrificing one-half of the quantum efficiency. By utilizing the tapered line structure and phase matching between optical waves and microwaves in our analyzed structure, a traveling-wave photodetector is more realizable and ultrahigh bandwidth can be attained due to removal of the extra input dummy load that sacrifices one-half of the total quantum efficiency. To investigate the advantages of TLDP over VMDP, we calculate their electrical bandwidth performances by using an analytic photodistributed current model. We adopted low-temperature-grown (LTG) GaAs-based metal-semiconductor-metal (MSM) traveling-wave photodetectors as example unit active devices in the analytic bandwidth calculation for their high-speed and high-power performances. Both VMDP and TLDP in our simulation are assumed to be transferred onto glass substrates, which would achieve high microwave velocity/impedance and make radiation loss negligible. The simulated bandwidth of a properly designed LTG GaAs MSM TLDP is /spl sim/325 GHz, which is higher than the simulated bandwidth of the LTG GaAs MSM VMDP with an open-circuit input end (/spl sim/240 GHz) and is almost comparable to the simulated bandwidth of an input-terminated LTG GaAs MSM VMDP (/spl sim/330 GHz). This proposed method can be applied to the design of high-bandwidth distributed photodetectors for radio-frequency photonic systems and optoelectronic generation of high-power microwaves and millimeter waves. 相似文献
157.
158.
159.
160.
George Ter-Stepanian 《Bulletin of Engineering Geology and the Environment》2002,61(3):197-205
The paper discusses the postulated suspension force, by which it is possible to explain some enigmatic phenomena observed
in different types of mass movements. This force is generated in thick suspensions as a result of friction between sinking
solid particles and static water. The suspension force is related to the seepage force but they have opposite directions.
Both forces form flow networks. Having explained the suspension force, the paper describes how this influences the movement
of material, particularly in debris flows. Enigmatic features and the mechanism of debris flows and lahars are explained by
virtue of the suspension force.
Electronic Publication 相似文献