论文写作与国际发表作业.docx

1. IntroductionNowadays, more and more attention has been paid to the utilization of low-temperature flue gases (120) released from several industry sectors (cement, steel, refineries), for its potential in reducing fossil fuel consumption and alleviating environmental problems. Organic Rankine Cycle (ORC) is proposed to recover low-grade energy and transform it into power. It is a proven technology, which allows the generation of electricity from low-temperature heat sources in a far more efficient way than conventional steam cycles 1,2.Much industrial flue gases may contain significant amount of moisture in vapor form (wet flue gases) due to many reasons such as flashing, washing, cleaning, and drying. The water dew point temperature of these flue gases could range between 55 and 65. Therefore, a considerable amount of heat is available in the form of latent heat of water vapor in these gases and cannot be recovered if flue gases are not cooled down to temperatures lower than the flue-gas dew point. The recovery of this large amount of heat improves the overall efficiency of the recovery system 3.An important factor influencing latent heat recovery is the corrosion problem associated to the cooling when flue gases contain sulfuric oxides (SO x), nitric oxides (NO x), and hydrochloric acid(HCl). However, many recovery technologies are already well developed and technically proven. Options include indirect contact condensation recovery and direct contact condensation recovery 3. In an indirect contact condenser, the heat is transferred between the two fluids (typically flue gases and working fluid) using an intervening wall (typically fin-and-tube heat exchanger). In this case, the heat-exchanger design requires using advanced materials such as Teflon” or equivalent coating to withstand exposure to corrosion problems. In a direct contact condenser, heat is transferred between the two fluids (typically gas and water) without an intervening wall thus there are no heat-transfer surfaces exposed to corrosion, clogging, and fouling. The two fluids move in a counter-flow direction, with one of them dispersed as small particles in a vertical column.Many investigations were carried out about low-grade heat recovery using ORC. Comprehensive researches on appropriate working fluids for low-temperature applications have been investigated by many authors such as 46. Others researchers have focused on the parametric optimization and performance analysis of the ORC like 710. Research background However, these studies deal with the indirect contact condensation recovery based on sensible heat extraction from flue gases with low moisture contents, or even though, with high moisture contents 11, but cooling the gases to a minimum safe temperature in order to prevent water vapor condensation and acid formation during gas flow. Existing problem. The originality of this study is to extend the ORC applications to low-grade gas heat sources with high moisture contents by pointing out the effect of water vapor condensation on cycle performance using the two condensing heat recovery processes (direct and indirect heat exchange). Research purpose2.IntroductionSO2 is widely known as a major pollutant that can cause various issues to the environment and public health. Although multiple methodologies have been developed to remedy such problems, a large amount of SO2 is still continuously emitted to the atmosphere every year. According to the estimation by publicly available data sets and inventories, the global anthropogenic SO2 released to the atmosphere in 2010 was over 100 Tg in total, of which more than 50% came from coal combustion. Industrial processes, mostly supported by fossil fuel combustion, are leading sources for the release of SO2. Flue industrially generated SO2, and it is regarded as an effective way to reduce SO2 emission. By now, various FGD techniques have been developed, among which the lime/limestone process is the most commonly used one, owing to its stability and high eciency. Research background. However, this process bears many drawbacks, including high capital costs, complex equipment, large occupation of land area, large consumption of fresh water, and formation of secondary pollutants. Application of carbonaceous materials in FGD provides an alternative with a series of advantages in contrast to the lime/limestone process, such as low capital cost, regeneration, and capability to recover sulfur. Many studies have indicated that carbonaceous materials, including activated carbon, coke, semi-coke, and activated carbon bers can effectively remove SO2 from ue gas with little negative impact on the environment. To date, great e orts have been devoted to improve the feasibility and eciency of carbonaceous materials in desulfurization processes by optimizing the preparation methodologies, parameters during desulfurization, and regeneration process. The properties of carbonaceous materials can be tailored by activation. In previous studies, a large number of physical and chemical activation agents have been used on coal or other carbonaceous precursors to achieve better adsorption capacities for various adsorbates, but the knowledge is yet to expand on the selection of activation methods exclusively designed for removal of SO2 from ue gas. Existing problem. In this paper, we employ a type of low-cost carbonaceous material, semi-coke, to investigate the inuence of activation methods on desulfurization capacity. Semi-coke is obtained from low-quality coal after going through a low-temperature carbonization process, during which there is an enrichment of oxygenated functional groups and the formation of undeveloped pore structure of the semi-coke caused by incomplete cracking of the coal precursor. These features of the semi-coke might be auspicious for application in desulfurization. For better utilization, an activation process by physical or chemical agents is usually carried out afterward. In this study, the semi-coke is respectively treated with CO2, KOH, ZnCl2, and H3PO4, all of which are widely used activation agents in the industrial preparation of activated carbonaceous materials. The inuences of temperature and ue gas compositions are conducted, which reveal that the removal of SO2 in the presence of O2 and H2O is an integrated process of adsorption and oxidation, with H2SO4 as the nal product. Research purpose In order to gain further insight into the fundamental mechanisms, the adsorption and desorption behaviors of the samples are analyzed by detailed characterizations of physical and chemical properties. Eventually, attempts are made to discuss possible reactions that occur in the adsorption and desorption processes, during which some key steps for desulfurization by activated semi-coke are identied. content arrangement3.IntroductionFatigue is one of the major causes for failure of structural members, especially in pipeline steel subjected to a cyclic load. Fatigue failure may occur because of changes in stress caused by frequent stop-and-start working pressure or outside forces, such as land movement and so on during operation 1 4. Hence, fatigue is a major concern in the evaluation of pipeline integrity. Generally, the total fatigue life mainly depends on fatigue crack initiation and propagation 5. However, fatigue crack growth life is dominant in the total life of pipelines because fracture caused by notches and cracks is the primary failure mode of pipelines under the condition of cyclic loading 6. Consequently, it is important and has prominent practical significance to study fatigue crack growth behavior.For the past decades, many researchers have carried out extensive work to study fatigue crack growth behavior of pipeline steel 7,8. Among them, the relationship between fatigue crack growth rate (da/dN) and the stress intensity factor range( K) was described by the well-known Paris equation 9,which means a straight line in the log log fit for the da/dN K plots. Nevertheless, some researches indicated the fatigue crack propagation curves of some materials are changed in the slope of the da/dN K plots, such as dual-phase steel and titanium alloy 10,11. Thus, it is not clear that whether Paris equation still can describe the non-linear fatigue crack propagation curve exactly. Furthermore, a new empirical model