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71.
The catalytic incineration of dimethyl sulfide and dimethyl disulfide [(CH3)2S and (CH3)2S2] over an MnO/Fe2O3 catalyst was carried out in a bench-scale catalytic incinerator. Three kinetic models (i.e., the power-rate law, the Mars and Van Krevelen model, and the Langmuir-Hinshelwood model) were used to analyze the results. A differential reactor design was used for best fit of kinetic models in this study. The results show that the Langmuir-Hinshelwood model may be feasible to describe the catalytic incineration of (CH3)2S and (CH3)2S2. This suggests that the chemical adsorption of O2 molecules is important in this incineration.  相似文献   
72.
Chung YC  Huang C  Tseng CP 《Chemosphere》2001,43(8):1043-1050
Biotreatment of various ratios of H2S and NH3 gas mixtures was studied using the biofilters, packed with co-immobilized cells (Arthrobacter oxydans CH8 for NH3 and Pseudomonas putida CH11 for H2S). Extensive tests to determine removal characteristics, removal efficiency, removal kinetics, and pressure drops of the biofilters were performed. To estimate the largest allowable inlet concentration, a prediction model was also employed. Greater than 95% and 90% removal efficiencies were observed for NH3 and H2S, respectively, irrespective of the ratios of H2S and NH3 gas mixtures. The results showed that H2S removal of the biofilter was significantly affected by high inlet concentrations of H2S and NH3. As high H2S concentration was an inhibitory substrate for the growth of heterotrophic sulfur-oxidizing bacteria, the activity of H2S oxidation was thus inhibited. In the case of high NH3 concentration, the poor H2S removal efficiency might be attributed to the acidification of the biofilter. The phenomenon was caused by acidic metabolite accumulation of NH3. Through kinetic analysis, the presence of NH3 did not hinder the NH3 removal, but a high H2S concentration would result in low removal efficiency. Conversely, H2S of adequate concentrations would favor the removal of incoming NH3. The results also indicated that maximum inlet concentrations (model-estimated) agreed well with the experimental values for space velocities of 50–150 h−1. Hence, the results would be used as the guideline for the design and operation of biofilters.  相似文献   
73.
74.
A 60-m flux tower was built on a 2100 m mountain for the measurement of the air pollutant concentration and the evaluation of dry deposition velocity in Central Taiwan. The tower was constructed in an evergreen broadleaf forest, which is the dominant species of forest in the world. Multiple-level SO2 concentrations and meteorological variables at the site were measured from February to April 2008. The results showed that the mean dry deposition velocities of SO2 were 0.61 cm s?1 during daytime and 0.27 cm s?1 during nighttime. From the comparison of the monthly data, a tendency was observed that the dry deposition velocity increases with LAI and solar radiation. Furthermore, it was observed that the deposition velocity was larger over wet canopy than over dry canopy, and that higher deposition velocities in the wet season were mainly caused by non-stomatal uptake of wet canopy. Over wet canopy, the mean dry deposition velocities of SO2 were estimated to be 0.83 cm s?1 during daytime and 0.47 cm s?1 during nighttime; and 0.44 cm s?1 during daytime and 0.19 cm s?1 during nighttime over dry canopy. There is good agreement between the results of this study and those in other studies and the predictions of Zhang et al. (2003a). The medians (geometric means) of derived rc during daytime are 233 (266) m s?1 over dry canopy and 147 (146) m s?1 over wet canopy. It was found that solar radiation is the critical important meteorological variable determining stomatal resistance during daytime. For non-stomatal resistance, clear dependencies were observed on the friction velocity and relative humidity.  相似文献   
75.
This study investigated the use of Cu/Al2O3, Co/Al2O3, Fe/Al2O3, and Ni/Al2O3 catalysts for the growth of carbon nanotubes (CNTs). These CNTs were used as support for Co catalyst preparation and Co/CNT catalysts were applied to a catalytic reaction to remove BTEX, PAHs, SO2, NO, and CO simultaneously in a pilot-scale incineration system. The analyzed results of EDS and XRD showed low metal content and good dispersion characteristics of the Al2O3-supported catalysts by excess-solution impregnation. FESEM analyzed results showed that the CNTs that were synthesized from Co, Fe, and Ni catalysts had a diameter of 20 nm, whereas those synthesized from Cu/Al2O3 had a diameter of 50 nm. Pilot-scale test results demonstrated that the Co/CNT catalyst effectively removed air pollutants in the catalytic reaction and that there was no obvious deactivation by Pb, water vapor, and coke deposited in the process. The thermal stabilization at 250 °C and hydrophobicity properties of CNTs enhanced the application of CNT catalysts in flue gas.  相似文献   
76.
Characterization of eco-cement paste produced from waste sludges   总被引:1,自引:0,他引:1  
Yen CL  Tseng DH  Lin TT 《Chemosphere》2011,84(2):220-226
In this study, marble sludge, sewage sludge, drinking water treatment plant sludge, and basic oxygen furnace sludge were used as replacements for limestone, sand, clay, and iron slag, respectively, as the raw materials for the production of cement in order to produce eco-cement. It was found that it is feasible to use marble sludge to replace up to 50% of the limestone and also that other materials can serve as total replacements for the raw materials typically used in the production of cement. The major components of Portland cement were all found in eco-cement clinkers. The eco-cement was confirmed to produce calcium hydroxide and calcium silicate hydrates during the hydration process, increasing densification with the curing age. The compressive strength (Sc) and microstructural evaluations conducted at 28 d revealed the usefulness of eco-cement. It was observed that the Sc data correlated linearly with the pore volume (P) data at 28 d. The proposed model equation could be represented as Sc = 178-461P (correlation coefficient, R2 = 0.96). Two parameters, the large capillary pore volume and the medium capillary pore volume, were evaluated using multiple regression analysis.  相似文献   
77.
Nuclear power plants are normally assumed to be safe when their radiation impact in all operational states is kept at a reasonably low level. However, accidentally released radioactive substances and ionizing radiation may lead to a situation that cannot maintain the regulatory prescribed dose limits for internal and external exposure of the personnel and population. Nuclear emergency preparedness and response in nuclear or radiological events have been of concern recently in international communities. Nuclear power plants may need to provide essential information regarding possible scenarios of accidental releases that might have short-term detrimental effects and long-term risks in nearby populated regions. This paper presents a synergistic integration of a source term model and a three-dimensional, time-dependent, numerical model (i.e., HOTMAC/RAPTAD), which was applied to simulate a specific scenario in which a vapor cloud was accidentally released from Maanshan (i.e., the third nuclear power plant) in South Taiwan. It aims at dealing with middle-range risk assessment for nuclear emergency preparedness and response. The solutions of such an integrated modeling platform can be found with numerical analyses that describe the processes of radionuclide generation, transport, decay, and deposition, giving the final risk assessment in a neighboring coastal city—Kaohsiung, South Taiwan. In addition, sensitivity analyses were performed to evaluate the internal consistency of model parameters, which further support the application potentials. Such a modeling technique is valuable because it can characterize the fate and transport of radioactive nuclides over the long term. The case study in South Taiwan uniquely demonstrates the feasibility and significance of such model integration.  相似文献   
78.
Abstract

The reaction between three different Ca-based sorbents and SO2 were studied in a medium temperature range (473–773 K). The largest SO2 capture was found with Ca(OH)2 at 773 K, 126.31 mg SO2?g Ca(OH)2 ?1, and the influence of SO2 concentration on the sorbent utilization was observed. Investigations of the internal porous structure of Ca-based sorbents showed that the initial reaction rate was controlled by the surface area, and once the sul-fated products were produced, pore structure dominated. To increase the surface area of Ca-based sorbents available to interact with and retain SO2, one kind of CaO/activated carbon (AC) sorbent/catalyst was prepared to study the effect of AC on the dispersion of Ca-based materials. The results indicated that the Ca-based material dispersed on high-surface-area AC had more capacities for SO2 than unsupported Ca-based sorbents. The initial reaction rates of the reaction between SO2 and Ca-based sorbents and the prepared CaO/AC sorbents/cata-lysts were measured. Results showed that the reaction rate apparently increased with the presence of AC. It was concluded that CaO/AC was the active material in the des-ulfurization reaction. AC acting as the support can play a role to supply O2 to increase the affinity to SO2. Moreover, when AC is acting as a support, the surface oxygen functional group formed on the surface of AC can serve as a new site for SO2 adsorption.  相似文献   
79.
Abstract

The continuous emission monitoring system (CEMS) can monitor flue gas emissions continuously and instantaneously. However, it has the disadvantages of enormous cost, easily producing errors in sampling periods of bad weather, lagging response in variable ambient environments, and missing data in daily zero and span tests and maintenance. The concept of a predictive emission monitoring system (PEMS) is to use the operating parameters of combustion equipment through thermodynamic or statistical methods to construct a mathematic model that can predict emissions by a computer program. The goal of this study is to set up a PEMS in a gas-fired combined cycle power generation unit at the Hsinta station of Taiwan Power Co. The emissions to be monitored include nitrogen oxides (NOx) and oxygen (O2) in flue gas. The major variables of the predictive model were determined based on the combustion theory. The data of these variables then were analyzed to establish a regression model. From the regression results, the influences of these variables are discussed and the predicted values are compared with the CEMS data for accuracy. In addition, according to the cost information, the capital and operation and maintenance costs for a PEMS can be much lower than those for a CEMS.  相似文献   
80.
The Sustainable Environment Research Center of National Cheng Kung University in Taiwan has set up a treatment plant to dispose of laboratory waste. In the treatment process, the residue from the incineration system and the physical and chemical system is vitrified by a plasma melting system. Part 1 of this study described the treatment path of metals during vitrification. In Part 2, plasma vitrified slag is reused by using a molding technology. Unsaturated polyester resin and glass fiber were used as the molding material and additive, respectively, in the molding process. With an appropriate mixing ratio of unsaturated polyester resin, glass fiber, and slag, the physical properties of composites improved, and the ultimate tensile strength reached 17.6 MPa. However, an excess amount of slag reduced the strength and even retarded the production of composites. Differential thermal analysis and the water bathing test results show that the composite decomposed at 80 degrees C and that it vaporized at 187 degrees C. Although the unsaturated polyester resin decomposed, the metal encapsulated in the slag did not leach out. The results show that the reuse of slag using molding technology should be taken into consideration.  相似文献   
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