The performance of a venturi scrubber in the removal of tar from gas in updraft gasification has been studied. The gasifier has been operated with a husk feed rate of 1.6 × 10?4 kg/s. The venturi scrubber has been operated at a superficial gas velocity of 56.4 m/s at the throat. A wide variety of scrubbing liquids having surface tensions ranging from 0.026 to 0.072 N/m have been used. The Qg/Ql, has been varied in the range of 1000–8000. The tar separation efficiency η has been found to vary from 51 to 98.5%. A mathematical model, assuming steady-state operation, has been developed considering very high pseudosolubility of tar in the scrubbing liquids. The predicted values of η have been compared with experimental results. The model satisfactorily explains the tar removal efficiency of the venturi for Qg/Ql values ranging from 4000 to 8000 for all scrubbing liquids. The following correlation has been developed for predicting venturi scrubber efficiency: . 相似文献
An ergonomics analysis of carpet installation tasks was performed. The purpose was to identify and quality potential sources of biomechanical trauma that may be responsible for the high rates of knee morbidity found by previous researchers among carpet layers. Nine carpet layers were studied either at an apartment building worksite or at a training school. Results from a job analysis indicated that workers spent approximatately 75% of their time in the kneeling position using a tool called a knee-kicker to stretch and install carpet. Awkward body postures were identified from films of workers installing carpets. At the moment of impact the knee is severely flexed, subtended angles were less than 60 degrees. To obtain measures of impact force on the knee, the kicker-tool was instrumented with a load cell. Workers who executed the hardest kicks with the tool produced impact peak forces that averaged 3019 newtons (N), which is equivalent to about four times body weight. Measures from an accelerometer attached to the worker's knee showed values in ecxess of 120 m/s2, which are comparable to those found during vigorous running and jumping exercises. The results imply that repetitive impact of the knee joint from the use of the knee-kicker combined with knee flexion, kneeling and squatting may be responsible for the high level of occupational knee-morbidity found among carpet layers. 相似文献
The initiation of crack growth was observed in single edge notched tensile specimens under plane strain conditions. The shape of the deformation zone varied from being balloon-like above 12 MPa and nearly planar below but neither shape conformed to that predicted by the conventional shear type yield criteria. The initial damaged zone grew at a constant velocity with a stress dependence ofV=V0n. The spectrum of damage morphologies that preceed crack growth consists of a leading edge of crack-like pores followed by a region of increasing fibrillation which is terminated by a region of increasing fibril fracture. 相似文献
Polymer-impregnated mortars were prepared by copolymerization of a monomer mixture of methyl methacrylate and styrene in the ratios of 13:87 and 40:60 using Co-60 gamma radiation. The copolymerization characteristics viz. the rate of polymerization, the extent of monomer loss, polymer loading, etc., were studied. The nature and molecular weight of the extractable polymer from the composite were determined. The flexural strength of the copolymer-impregnated composites was found to be better than that of the composites impregnated with component homopolymers. 相似文献
The liquid phase benzoylation of benzene with benzoyl chloride (BOC) to benzophenone is catalyzed by various zeolites at 353 K. Zeolite H-beta is found to be more active than the other zeolites. The conversion of benzoyl chloride to benzophenone over H-beta increases significantly with increase in the reaction time, temperature, catalyst/BOC (wt/wt) and benzene/BOC (mole) ratios. The yield of benzophenone decreases with increase in SiO2/Al2O3 ratio and isomorphous substitution of Al-by Ga- and Fe-in zeolite H-Al-beta in the following order: Al-> Ga-> Fe-H-beta suggesting that high density of acidic centers along with strong acid sites are required for the reaction. 相似文献
A comprehensive scientific assessment of CH4 budget estimation for Indian rice paddies, based on a decade of measurements in India, is presented. Indian paddy cultivation areas contain soils that have low to medium levels of soil organic carbon. The average seasonally integrated CH4 flux (Esif) values calculated from these measurements were 15.3 ± 2.6 g m–2 for continuously flooded (CF), 6.9 ± 4.3 g m–2 for intermittently flooded (IF) single aeration (SA) and 2.2 ± 1.5 g m–2 for IF multiple aeration (MA) rice ecosystems. For CF and IF (MA) rice ecosystems having high soil organic carbon, without organic amendments, the CH4 flux (Esif) may be increased by 1.7 times relative to low soil organic carbon, whereas it may enhance by 5.3 for CF if amended organically. Organic amendment and high soil organic carbon paddy areas do not alter the methane budget estimates for India (3.6±1.4 TgY–1) much, due to their small paddy harvested area. Methane estimated using average emission factors (Esif) for all paddy water regimes, which include harvested areas having soils with high organic carbon and organic amendments, may give a budget of 5 TgY–1 for India. 相似文献
An attempt is made to develop a novel series of cable sheathing compounds with variation in chlorine content and sufficient fire retardance and unique low-smoke characteristics. These are prepared by blending PVC and functionalized polyolefins in different compositions. PE and EPDM have been functionalized by grafting dibutyl maleate (DBM) using DCP as initiator. FRLS compounds made from PVC-functionalized polyolefin blends possess the special characteristics of low-smoke, low-acid-gas generation, increased fire retardance, and improved volume resistivity, which are much better in comparison with a typical PVC sheathing compound. Thermoplastic elastomer (TPE) based nonhalogen FRLS compounds are also reported. The mechanisms for grafting, polymer-polymer and polymer-filler interactions have been presented. 相似文献
One major constraint of the agricultural uses of fly ash (FA) is the low availability of different plant nutrients despite their high occurrence in the total amount. However, degrading FA through increased microbial activity can improve the availability of these nutrients substantially. It has been found that intestines of epigeic earthworms contain a high concentration of different microorganisms. Therefore, in the present study we addressed the effects of vermicomposting technology on the solubility of some micronutrient cations (Fe, Mn, Cu, and Zn) and some heavy metals (Pb, Cd, and Cr) in different combinations of fly ash and organic matter, applied in the form of cow dung (CD). Various combinations of FA and CD were treated with and without an epigeic earthworm (Eisenia fetida) and the solubility of different trace elements in the treatments were estimated periodically. The results revealed that the inclusion of epigeic earthworm Eisenia fetida in different combinations of fly ash and cow dung converted a considerable amount of the micronutrients into bio-available forms. On the other hand, the solubility of heavy metals tended to be reduced by the microorganisms, presumably by formation of some organo-metallic complex. Application of these vermicomposted FA and CD combinations to a red lateritic soil was found to improve the soluble Fe, Mn, Cu, and Zn status of the soil. Furthermore, the use of vermicomposted FA and CD (1:1) in potato cultivation demonstrated that use of this mixture at 10 ton per hectare (t ha−1; fresh weight) was able to compensate 80% of the recommended NPK fertiliser, along with farm yard manure application, without compromising the crop yield. 相似文献