Carbon capture and storage using coal fly ash with flue gas

Clean Technologies and Environmental Policy - Rising CO2 emissions call for actions to urgently address climate change and its impacts. To avoid the harmful consequences of climate change, limiting...     

Carbon dioxide laser fabrication of fused-fiber couplers and tapers

We report the development of a fiber taper and fused-fiber coupler fabrication rig that uses a scanning, focused, CO(2) laser beam as the heat source. As a result of the pointlike heat source and the versatility associated with scanning, tapers of any transition shape and uniform taper waist can be produced. Tapers with both a linear shape and an exponential transition shape were measured. The taper waist uniformity was measured and shown to be better than +/-1.2%. The rig was also used to make fused-fiber couplers. Couplers with excess loss below -0.1 dB were routinely produced.     

Carbon dioxide gas sensor based on ionic liquid-induced electrochemiluminescence

Electrochemiluminescence of the luminol-O(2) system in an electrolyte-free N,N-dimethylformamide (DMF)-dipropylamine (DPA) cosolution is induced by the formation of a carbamate ionic liquid (IL) from the reaction between CO(2) and DPA, on the basis of which a facile ECL sensor for measuring atmospheric CO(2) has been developed. This ECL sensing method shows several advantages in the detection of CO(2), such as high safety, high selectivity, wide linear response range, and good sensitivity. The gas sensor was found to have a linear response range from 100 ppm to 100 v/v% and a detection limit of 80 ppm (at signal-to-noise ratio of 3). This is the first reported IL-induced ECL sensor for a gas, thus the principle of this type of sensor and the IL-induced ECL mechanism have been demonstrated in detail.     

膜气体吸收技术脱除电厂烟气二氧化碳的研究进展

介绍了气体分离膜技术、液膜吸收技术和气体吸收膜技术,综述了膜气体吸收技术在减少电厂模拟烟气CO_2排放中的研究状况,并对不同类型的电厂采用不同工艺的经济性进行了比较分析.总结了膜气体吸收技术发展与应用中存在的不足,指出膜气体吸收技术的发展前景.     

Evaporation of NH3 in NH3/H2 atmosphere by 25 bar for neutral gas absorption refrigeration units

The present work considers the evaporation process ofNH ₃ inNH ₃/H₂ atmosphere, that takes place in neutral gas absorption refrigeration units. The data obtained are used to calculate the “psychrometric problem” and the evaporation process within an insulated tube. The “psychrometric problem” deals with the determination of the mass fraction of theNH ₃/H ₂ gas mixture from known “dry” and “wet bulb” temperatures for Lewis numbers not equal to one. The results are in good agreement with some existing experimental data.     

Pollutants in incineration flue gas

Previous studies have shown that pollutants from incineration include heavy metals, organic compounds, particulate and acid gas. However, most studies on a single pollutant, it is rare for a study to concentrate on all possible pollutants and the relations between these pollutants under various incineration conditions. The objective of this work was to experimentally study the effect of different operating conditions on the pollutants emitted during incineration and the relations between these pollutants. The operating conditions of the experiments included the temperature of the combustion chamber and the species of organics. The findings indicated that the concentration of hydrogen chloride (HCl) in the presence of polyvinyl chloride (PVC) was higher than that of sodium chloride (NaCl). Regardless of what Cl-containing feedstock was added, the concentration of chromium (Cr) was constant. When organic chloride was added, Cr was the main metallic element which influenced the formation of polycyclic aromatic hydrocarbons (PAHs). On the other hand, when inorganic chloride (NaCl) was added, lead (Pb) was the major element.     

Adsorbents for capturing mercury in coal-fired boiler flue gas

This paper reviews recent advances in the research and development of sorbents used to capture mercury from coal-fired utility boiler flue gas. Mercury emissions are the source of serious health concerns. Worldwide mercury emissions from human activities are estimated to be 1000 to 6000 t/annum. Mercury emissions from coal-fired power plants are believed to be the largest source of anthropogenic mercury emissions. Mercury emissions from coal-fired utility boilers vary in total amount and speciation, depending on coal types, boiler operating conditions, and configurations of air pollution control devices (APCDs). The APCDs, such as fabric filter (FF) bag house, electrostatic precipitator (ESP), and wet flue gas desulfurization (FGD), can remove some particulate-bound and oxidized forms of mercury. Elemental mercury often escapes from these devices. Activated carbon injection upstream of a particulate control device has been shown to have the best potential to remove both elemental and oxidized mercury from the flue gas. For this paper, NORIT FGD activated carbon was extensively studied for its mercury adsorption behavior. Results from bench-, pilot- and field-scale studies, mercury adsorption by coal chars, and a case of lignite-burned mercury control were reviewed. Studies of brominated carbon, sulfur-impregnated carbon and chloride-impregnated carbon were also reviewed. Carbon substitutes, such as calcium sorbents, petroleum coke, zeolites and fly ash were analyzed for their mercury-adsorption performance. At this time, brominated activated carbon appears to be the best-performing mercury sorbent. A non-injection regenerable sorbent technology is briefly introduced herein, and the issue of mercury leachability is briefly covered. Future research directions are suggested.     

A xenon gas purity monitor for EXO

We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.     

Screen-printed Tin-doped indium oxide (ITO) films for NH3 gas sensing

Gas sensors using metal oxides have several advantageous features such as simplicity in device structure and low cost fabrication. In this work, Tin-doped indium oxide (ITO) films were prepared by the screen printing technique onto glass substrates. The granular and porous structure of screen-printed ITO are suitable for its use in gas sensing devices. The resistance of the ITO films was found to be strongly dependent on working temperatures and the nature and concentration of the ambient gases. We show that screen-printed ITO films have good sensing properties toward NH₃ vapours. The observed behaviors are explained basing on the oxidizing or the reducer nature of the gaseous species that react on the surface of the heated semi-conducting oxide.     

Effect of laser treatment on the gas sensitivity of tin dioxide films

It is shown that the sensitivity of antimony-doped polycrystalline SnO₂ films can be increased by treatment with laser pulses. Pis’ma Zh. Tekh. Fiz. 24, 57–60 (April 12, 1998)     

Materials for flue gas desulfurization systems operating in Korea and their failures

Abstract

Most flue gas desulfurization (FGD) systems operating in Korea are wet systems which are exposed to aggressive chemical and mechanical environments. Many kinds of materials such as stainless steels, nickel-based alloys, fiberglass reinforced plastic (FRP), C276 or Ti clad steels, and non-metallic coatings/linings over carbon steel have been used for the FGD systems, with their ductwork and chimney exposed in the severe environments. The materials are required to survive during their design life, but some materials are not sufficiently resistant to the corrosive environments in the FGD systems, resulting in the failures of materials and hence increased maintenance costs. Especially, the non-metallic materials and stainless steels have been used extensively in early installations in order to reduce the initial material costs, but they frequently failed early in the severe corrosive environments. This paper presents some representative examples of failures that occurred at the wet FGD systems operating in Korea and their counter measures.     

Mechanisms and strategies for ash deposition reduction in flue gas heat exchanger

Clean Technologies and Environmental Policy - Ash deposition in flue gas heat exchanger affects its heat transfer performance and lifecycle, which becomes a crucial factor restricting the efficient...     

氧化石墨烯的制备及其对NH3的敏感特性研究

石墨烯独特的原子结构赋予其电学、热学、力学等方面的优异性能,在诸多领域具有广泛的应用。氧化石墨烯不仅具有石墨烯结构特点,而且具有大量的含氧官能团,增强了对气体的吸附能力,更适合应用于气敏传感器。通过改进的Hummer方法制备了片状多层氧化石墨烯,并对不同浓度的NH3进行敏感特性测试。结果表明氧化石墨烯对NH3具有良好的响应,在(1.5～3.5)×10-4范围内呈线性关系。     

Silicon nitride films deposited from SiF4/NH3 gas mixtures

Silicon nitride films have been deposited from SiF₄/NH₃/H₂ gas mixtures. The deposition reaction at high pressure (52 torr), takes place only for temperatures above 800°C. In the temperature range 800–1000°C the reaction is controlled by a surface process. The increase in H₂ and SiF₄ partial pressures enhances the deposition rate. The SiF₄ molecules provide a high concentration of available silicon atoms, while the hydrogen molecules inhibit the etching effect of the free fluorine atoms. Finally, the effect of an r.f. plasma in the chemical vapour deposition reaction has been evaluated.     

Carbon nanotube-zirconium dioxide hybrid for defluoridation of water

This study presents the synthesis of zirconia/multi-walled carbon nanotube (ZrO2/MWCNTs) hybrid as a novel sorbent for water defluoridation. The synthesis was facilitated by the high degree of functionalization of MWCNTs using a microwave assisted process. In the final product, nearly 3% of the carbon atoms were attached to ZrO2. The ZrO2/MWCNTs were effective in fluoride removal and mechanistic aspects of the process are presented. The research findings highlight the potential application for the use of MWCNT hybrids in environmental remediation.