Papers by Keyword: Sulfur Dioxide

Abstract: The influences of the regeneration temperature and SO₂volume fraction on regeneration kinetics behavior of Fe₂O₃ sorbent as a high-temperature desulfurization sorbent were researched by TGA (Thermos gravimetric analyzer) in this work. The main regeneration product of iron oxide desulfurization sorbent was Fe₂O₃ and sulfur in SO₂ atmosphere which has an important practical significance for pollution control of H₂Sandrecycleofsulfur. The results indicate that Fe₂O₃ desulfurization sorbent was completely regenerated at temperature of 725-775 °C and the higher regeneration temperature and volume fraction of SO₂ is benefit to improve regeneration reaction rate. The regeneration reaction of Fe₂O₃ sorbent in SO₂ atmosphere can be first order reaction obtained by the equivalent grain model, and the controlling process of regeneration reaction is change from the chemical reaction control to the diffusion control in the whole regeneration process. The chemical reaction apparent activation energy and the corresponding frequency factor of chemical reaction are 145.31 kJ/mol and 0.0063 m/s, respectively. And that of diffusion are 50.73 kJ/mol and 4.38×10^-3 m²/s, respectively.

Abstract: The paper presents a solution for modeling and simulation of the adsorption process of the sulfur dioxide in natural zeolites. The adsorption process is modeled as a distributed parameter process, its dynamics depending on three independent variables: time and two spatial variables. In order to simulate the adsorption process, an original form of the approximating analytical solution which describes the process work in dynamical regime is proposed and used. The coefficients of the approximating analytical solution are determined using experimental data obtained from the real plant. A direct practical application, resulted through the simulation of the obtained mathematical model, is the approximation of the time period in which the saturation of the zeolites of different dimensions occurs. Having the mentioned time period, the operators from the industrial field can decide with precision the moment when a zeolite block has to be replaced in order to avoid the environment pollution.

Abstract: Lychee (LYchee chinensis) is a tropical, subtropical climate zone of special fruit, the“southern good fruit” ,China is the world’ largest producer of litchi, commercial long history of cultivation. Is also one of the most competitive on the international fruit market fruit present. Litchi fruit flavor is unique, colorful, nutrient-rich, loved by the people. But its fruit ripening is in the hot season, due to post-harvest browning (loss of red) and fruit rot rapid deterioration leaving the fruit, post harvest life at room temperature is less than three days, this short postharvest life strictly limits litchi long-distance transportation, sale and consumption.

Abstract: This article studied about the air pollution in China. The main causes of the air quality deterioration in the country were analyzed as well as possible ways of the environmental situation improvement were suggested.

Abstract: A new sensor with Pt and Ag mixture paste on the surface to act as the sensing electrode (Ag) and catalyst (Pt) to oxidized SO₂ to SO₃ for sulfur dioxide was fabricated. The effect of auxiliary phase on the sensing properties has been investigated and the device with auxiliary phase showed better performance and the effect of operating temperature has also been studied. It shown that 500°C would be more suitable than 600°C for the device gas test.

Abstract: The decomposition of sulfur hexafluoride (SF6) in overheated electric equipment at different temperature in high humidity was simulated in the study. SF6 is very stable and not significantly decomposed at 200 °C, 250 °C and 300 °C. SF6 is significantly decomposed at 350 °C. SF6 is more easily to be decomposed and decomposed more rapidly at higher temperature. The concentrations of SF6 byproducts are much higher at higher temperature. SF6 will be decomposed to format HF. The concentration of HF will decrease when its concentration increases up to a certain concentration. It may be because that HF was strongly corrosive and its corrosion to inner equipment made the concentration of HF decreasing.

Abstract: Metal oxide semiconductors materials such as zinc oxide (ZnO) are often used in the fabrication of chemoresistive gas sensors, but ZnO materials require high operating temperatures to operate. In another side, carbon nanotubes (CNT) have many distinct properties and recently have been exploited as the next generation of sensors, including chemoresisitive type gas sensors. This study was aimed to investigate the performance of MWNT-ZnO composites as SO₂ gas sensitive layer. By fabricate composites of MWNT and ZnO, have been obtained a sensitive layer that can be utilized for application as gas sensitive layer with relatively lower operating temperature. A sensitive layer of MWNT-ZnO based composites have been successfully fabricated on a alumina substrate and several characterization techniques has been performed, i.e. XRD, SEM and EDS to study the formed crystalline phase, the morphology of the nanostructures, and the elemental composition of synthesized composites. MWNT-ZnO sensitive layer was tested by exposure to SO₂ gas at various operating temperatures and gas concentration. From the performance testing results, it could be found that the composite materials have a prospective as a gas sensor at lower operating temperature with short response time and good sensitivity.

Abstract: With the development of electrolytic aluminum in our country, sulphur content in aluminum anode increased year by year, thus there is the risk of SO₂ discharge over standard in exhaust gas treatment in electrolytic aluminum industry. Further, the waste heat from exhaust gas of electrolytic aluminum has not been made full use at present. It is necessary to development new exhaust gas treatment and utilization technology. In this study, a scheme about electrolytic aluminum exhaust gas cascade utilization has been proposed according to the characteristics of electrolytic aluminum exhaust gas. The electrolytic aluminum exhaust gas after dry treatment could be sent to power plant boiler as combustion air, as the discharge of electrolytic aluminum exhaust gas and air pollutants could be decreased greatly. After the comparison of techno-economic analysis, the discharge by the scheme of cascade utilization was less than that with desulfurization, with more economic benefit. Thus it is worth to be extended, since the scheme of electrolytic aluminum exhaust gas cascade utilization showed good techno-economy.

Abstract: Zinc oxide nanostructures were successfully synthesized via a facile hydrothermal method. Structural characterizations by means of X-ray diffraction and field emission scanning electron microscopy were conducted, and the as synthesized products composed of numerous nanorods have a hierarchical flower-type structure. The optimum operating temperature of the sensing material to sulfur dioxide is about 270 °C, and the linear correlation coefficient of the sensing material to sulfur dioxide gas is equal to 0.978. Furthermore, this sensing material demonstrates reversible sensing response and rapid response-recovery characteristic to sulfur dioxide. All results indicate our products a promising sensing material for recognition of sulfur dioxide.

Abstract: In this investigation, we have synthesized pure and copper decorated tin oxide nanostructures with a facile yet environment-friendly hydrothermal route. The sensing materials are characterized by X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Thick-film gas sensors are fabricated from the as-prepared samples, and their gas sensing performances towards sulfur dioxide are calculated and evaluated by a Chemical Gas Sensor-8 intelligent gas sensing analysis system automatically.