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In order to obtain a reduced methane combustion mechanism for predicting combustion field and pollutants accurately in CFD simulations with a lower computational cost, a reduced mechanism with 22 species and 65 steps of reactions from GRI-Mech 3.0 was obtained by direct relation graph method and sensitivity analysis. The ideal reactor calculation and VV&A (Verification, Validation, and Accreditation) in CFD were carried out using the proposed mechanism. The results showed that the proposed mechanism agrees well with the detailed mechanism in a wide range of operating conditions; the temperature field and species can be predicted accurately in CFD simulations (RANS and LES models), and the NO prediction error of an industrial gas turbine combustor outlet is less than 2×10−6. The proposed mechanism has high engineering values. [ABSTRACT FROM AUTHOR]

During fluidized bed gasification, sulfur in coal will be released, which will lead to environmental pollution. The release behavior of sulfur in fluidized bed gasification has not been fully studied, although fluidized bed gasification technology has a promising prospect. Thus the release behaviors of sulfur during fluidized bed gasification were investigated comprehensively through two aspects: temperature and reaction atmosphere. During air gasification, the main gaseous sulfur is H2S, followed by COS, and the yield of SO2 and CS2 is low. With the increase of temperature, both of the released sulfur and the percentage of inorganic sulfur in gas phase increase. Under the same working condition, the distributions of sulfur forms in gasification residues are analogous. Organic sulfur is the dominate sulfur forms in the gasification residues. Sulfate in residues increases while organic sulfur decreases with increasing temperature. Among three reaction atmospheres (CO2/steam/air) studied, the yield of H2S is the most among the above four kinds of gaseous sulfur. The percentage of H2S in gaseous sulfur (H2S/Sg) is the highest in the process of steam gasification, while most sulfur is released during air gasification. The sequencing of H2/CO is the same as that of H2S/Sg, while the trend of sulfur release rate is consistent with that of carbon conversion rate. The distributions of sulfur species in the fly ash of CO2 gasification and steam gasification are similar, while the sulfate content in the fly ash of air gasification is the highest. [ABSTRACT FROM AUTHOR]

The spouted-fluidized bed is modified from the classical fluidized bed device, which combines the features of spouted and fluidized beds. In the present work, the performance of oxy-fuel spouted-fluidized bed combustion with under bed feeding and its effect on NO emission were systematically investigated. The results revealed that it was feasible to use a spouted-fluidized bed combustor for oxy-fuel combustion with real flue gas recycling. The transition from air combustion to oxy-fuel combustion was smooth and the concentration of CO2 in the flue gas could be as high as 90% steadily (dry base). Increasing the reaction temperature exhibited a negative effect on NO emission. Compared with that under the shallow bed, the concentration of NO in the flue gas was lower under the deep bed condition. Besides, the utilization of crush particles was favorable for suppressing NO emission because of the promoted mixing between coal particles and solid bed materials. Furthermore, the addition of limestone was proven to undesirably increase the NO emission during oxy-fuel spouted-fluidized bed combustion. [ABSTRACT FROM AUTHOR]

The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery semi-coke. The characteristic of low volatile results in poor combustion performance and high NOx emission, and to co-fire with bituminous coal is a practical strategy to address this problem. However, the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently understood. In addition, the influences of secondary air arrangement, the boiler operation load, and the fuel type on co-combustion process are still unclear, which is urgent to be further explored. In the present study, experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NOx emission features of semi-coke and coal. The results demonstrated that the "out-furnace method" was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%, due to the limited combinations of the semi-coke injection position. It was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the "in-furnace method" to improve the overall co-combustion performance. The critical value of the separated over fire air ratio in this study was 27.5%, over which a slight drop of carbon content in fly ash could come about. Moreover, the elevation in the proportion of separated over fire air gave rise to the significant decline of NOx concentration. The constricted secondary air arrangement was preferred to be employed due to the high boiler efficiency. The separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NOx emissions and the coking of nozzles. For the load reduction regulation method adopted in this study, the NOx concentration first rose and then dropped, while the burnout ratio decreased obviously as the operation load was reduced. Different combinations of coal and semi-coke generated significant influences on co-combustion behaviors within the furnace. The NOx generated by high-volatile fuel (bituminous coal) combustion was mainly affected by volatile-N, while the NOx generated by low-volatile fuel (semi-coke) was mainly impacted by char-N. This study is of guiding significance for the efficient and clean utilization and beneficial to the large-scale application of powder semi-coke in power plants. [ABSTRACT FROM AUTHOR]

The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer (TGA) at medium temperatures (650–800°C). The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The Brunauer-Emmett-Teller (BET) surface area of the samples was tested by N2 adsorption, and the morphologies of the samples were characterized by scanning electron microscopy (SEM). Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char, and the gasification rate of the char could be enhanced further with the introduction of CaO. The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735°C. The char conversion curves with or without CaO were fitted by the modified volumetric model (MVM). The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously, but made little changes on the activation energy. It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO, which facilitated the migration of the catalyst ions and the generation of C(O) intermediates for the gasification. [ABSTRACT FROM AUTHOR]

Background: As a degenerative joint disease with severe cartilage destruction and pain, osteoarthritis (OA) has no satisfactory therapy to date. In traditional Chinese medicine (TCM), Aconitum carmichaeli Debeaux derived Hei-shun-pian (Hsp) has been developed for joint pain treatment. However, it causes adverse events in OA patients. Long-time decoction has been traditionally applied to reduce the aconite toxicity of Hsp and other aconite herbs, but its detoxifying effect is uncertain. Methods: Hsp was extracted with dilute decoction times (30, 60, and 120 min) and evaluated by toxicological, chemical, pharmacological assays. Acute toxicity assay and chemical analysis were employed to determine the toxicity and chemoprofile of Hsp extracts, respectively. Since the detoxified Hsp (d Hsp) was defined, its therapeutic effect was evaluated by using an OA rat model induced by monosodium iodoacetate. d Hsp at 14 g/kg was orally administered for 28 days, and the pain assessments (mechanical withdrawal threshold and thermal withdrawal latency) and histopathological analyses (HE and safranin-O staining) were performed. Real-time PCR (qPCR) was applied to determine the molecular actions of d Hsp on cartilage tissue and on chondrocytes. MTT assay was conducted to evaluate the effect of d Hsp on the cell viability of chondrocytes. The cellular and molecular assays were also conducted to analyze the functions of chemical components in d Hsp. Results: The chemoprofile result showed that the contents of toxic alkaloids (aconitine, mesaconitine, and hypaconitine) were decreased but that of non-toxic alkaloids (benzoylaconitine, benzoylmesaconitine, and benzoylhypaconitine) were increased with increasing decoction time. Acute toxicity assay showed that only Hsp extract with 120 min decoction was non-toxic within the therapeutic dose range. Thus, it was defined as d Hsp for further experiment. In OA experiment, d Hsp significantly attenuated joint pain and prevented articular degeneration from MIA attack. qPCR data showed that d Hsp restored the abnormal expressions of Col10 , Mmp2 , Sox5 , Adamts4/5/9 , and up-regulated Col2 expression in rat cartilage. In vitro , d Hsp- containing serum significantly proliferated rat chondrocytes and regulated the gene expressions of Col2 , Mmp1 , Adamts9 , and Aggrecan in a similar way as the in vivo data. Moreover, aconitine, mesaconitine, and hypaconitine exerted cytotoxic effects on chondrocytes, while benzoylaconitine and benzoylhypaconitine except benzoylmesaconitine exhibited similar molecular actions to d Hsp , indicating contributions of benzoylaconitine and benzoylhypaconitine to d Hsp. Conclusions: This study defined d Hsp and demonstrated d Hsp as a potential analgesic and disease modifying agent against OA with molecular actions on the suppression of chondrocyte hypertrophy and extracellular matrix degradation, providing a promising TCM candidate for OA therapy. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphene's excellent physical, electrical, mechanical and passivating properties are revolutionizing the world of nanotechnology. In its beginning, graphene was only used as the conductive channel in metal-oxide-semiconductor field-effect transistors and as metallic electrode in capacitors, but the development of chemical vapor deposited graphene on metal catalysts, together with an ingenious process to transfer it to arbitrary substrates extended the use of graphene to many other applications. The main problem of this methodology is to get a good adhesion between the graphene and the target substrate that ensures both protection and interaction. In this paper, we analyze the capability of graphene to adapt to underlying simple and complex substrates. We observe the important adhesion differences depending on the graphene thickness and the target substrate roughness. We take advantage of graphene coatings to protect different materials from high current densities, mechanical frictions and oxidation. The findings and prototypes here designed may open the way to extend the use of graphene as protective coating. [ABSTRACT FROM AUTHOR]

Wet limestone scrubbing is the most common flue gas desulfurization process (FGD) for control of sulfur dioxide emissions from the combustion of fossil fuels. Forced oxidation, which controls the overall reaction of the sulfur dioxide absorption, is the key path of the process. Manganese which comes from the coal is one of the catalysts during the forced oxidation process. In the present work, the two-film theory was used to analyze the sulfite forced oxidation reaction with an image boundary recognition technique, and the oxidation rate was experimentally studied by contacting pure oxygen with a sodium sulfite solution. There was a critical sulfite concentration 0.328 mol/L without catalyst or at a constant catalyst concentration value. The kinetics study focused on the active energy of the reaction and the reaction constant k; furthermore, we obtained the order with respect to the sulfite and Mn2+ concentrations. When the Mn2+ catalyst concentration was kept unchanged, the sulfite oxidation reaction rate was controlled by dual film and the reaction kinetics was first order with respect to sulfite while SO concentration was below 0.328 mol/L; the sulfite oxidation reaction rate was controlled by gas film only and the reaction kinetics was zero order with respect to sulfite while SO concentration over 0.328 mol/L. When SO concentration was kept unchanged, the sulfite oxidation reaction rate depended on gas-liquid mass transfer and the reaction kinetics was different in various stages with respect to Mn2+ concentrations. [ABSTRACT FROM AUTHOR]

Emissions reduction in industrial processes, i.e. clean production, is an essential requirement for sustainable development. Fossil fuel combustion is the main emission source for gas pollutants, such as NOX, SO2 and CO2, and coal is now a primary energy source used worldwide with coal combustion being the greatest atmospheric pollution source in China. This paper analyzes flue gas cleaning by ammonia scrubbing (FGCAS) for power plants to remove gaseous pollutants, such as NOX, SO2 and CO2, and presents the conceptual zero emission design for power plants. The byproducts from the FGCAS process can be used in agriculture or for gas recovery. Experimental results presented for SO2 removal from the simulated flue gas in a continuous flow experiment, which was similar to an actual flue gas system, showed that the effectiveness of the ammonia injection or scrubbing depends on the temperature. The FGCAS process can effectively remove SO2, but the process temperature should be below 60 °C or above 80 °C for SO2 reduction by NH3 scrubbing. [Copyright &y& Elsevier]