Interactions between two in-line drops rising in pure glycerin☆

The behaviors of time-dependent interaction between two buoyancy-driven in-line deformable drops rising in pure glycerin at Re b 1 were studied, where the diameter for the leading drops ranged from 9.51 mm to 12.6 mm and for trailing drops from 12.7 mm to 15.8 mm. The situation while a larger drop chasing a smal er one was specifically considered which typical y led to the smal er drop“coating”the larger one. Two approaches, the geometric feature approach and the energy change one, were used to judge the starting and ending times of the interaction between two drops. Based on a conical wake model, the drag coefficient of two approaching drops was calculated. Due to the approaching effect of the trailing drop, the leading drop was accelerated and the average drag coefficient was smal er than that for a free rising single drop. The frequency spectrums of the lateral oscillation of two drops during the interaction were obtained by using Fourier analysis. The oscillation frequency of the interactional drops was also different from that for a free rising single drop because of the wake effect produced by the leading drop. Due to a superposition of the drop shape oscil ation and the drop internal circula-tion, the transverse oscil ation frequencies of two drops have the same trend during the approaching process. ? 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

The correlation between nitrogen species in coke and NOx formation during regeneration☆

Nitrogen oxides(NO x)emission during the regeneration of coked fluid catalytic cracking(FCC)catalysts is an environmental issue.In order to identify the correlations between nitrogen species in coke and different nitrogencontaining products in tail gas,three coked catalysts with multilayer structural coke molecules were prepared in a fixed bed with model compounds(o-xylene and quinoline)at first.A series of characterization methods were used to analyze coke,including elemental analysis,FT-IR,XPS,and TG–MS.XPS characterization indicates all coked catalysts present two types of nitrogen species and the type with a higher binding energy is related with the inner part nitrogen atoms interacting with acid sites.Due to the stronger adsorption ability on acid sites for basic nitrogen compounds,the multilayer structural coke has unbalanced distribution of carbon and nitrogen atoms between the inner part and the outer edge,which strongly affects gas product formation.At the early stage of regeneration,oxidation starts from the outer edge and the product NO can be reduced to N_2 in high CO concentration.At the later stage,the inner part rich in nitrogen begins to be exposed to O_2.At this period,the formation of CO decreases due to lack of carbon atoms,which is not bene ficial to the reduction of NO.Therefore,nitrogen species in the inner part of multilayer structural coke contributes more to NO X formation.Based on the multilayer structure model of coke molecule and its oxidation behavior,a possible strategy to control NO X emission was discussed merely from concept.     

Development trends and market analysis of China''''s plastics industry

China's plastics industry has witnessed the leap-forward development with the stable and sound growth of national economy,having increased its economic and technical indicators stably and greatly for consecutive ten years.     

Burn-out of pulverised coal and biomass chars☆

The burn-out of carbon in pulverised fired power stations is commercially important. Interest in the burn-out of biomass chars is growing because biomass is increasingly being co-fired with coal to reduce the carbon dioxide emissions. The significance of carbon burn-out is that it is linked with the efficiency of the plant and the suitability of the coal ash for construction purposes. Residual carbon in ash has generally increased in recent years because of the influence of the lower temperatures and slower mixing resulting from the use of low NO_x burners. The amount of unburned carbon is thus a function of the plant design and operating conditions but it is also linked to the ease of combustion of the coal and the char formed. These latter factors are related to the properties of the coal and this paper attempts to quantify the impact of certain coal and char properties on carbon-out. An approach for assessing biomass combustion performance is also discussed.     

Adsorption methods to study microporosity in coals and carbons—a critique

This article discusses problems of the interpretation of adsorption data from microporous coals and carbons. Structure in coals and carbons is briefly reviewed and ultramicroporosity, microporosity and supermicroporosity are defined. Problems associated with activated diffusion, molecular sieve effects, cooperative adsorption effects, the use of polar adsorbates and the understanding of limitations and value of theoretical adsorption equations are assessed. The Dubinin-Radushkevich and Dubinin-Astakhov equations appear superior to Langmuir or BET equations in terms of differentiating and describing the microporosities of coals and carbons. Their critical use is recommended.     

Dilemma between Encouragement and Restriction

A deputy director from the research in-stitute of petrochemical economics andtechnology once made a survey inGuangzhou. She told that small standbygenerators that use diesel are often seenin some small restaurants. During theperiods of peak power usage these smallgenerators are used, otherwise such res-taurants would have to close due topower supply stoppage.     

Modeling and optimization for oil well production scheduling☆

In this paper, an oil wel production scheduling problem for the light load oil wel during petroleum field exploi-tation was studied. The oil well production scheduling was to determine the turn on/off status and oil flow rates of the wel s in a given oil reservoir, subject to a number of constraints such as minimum up/down time limits and well grouping. The problem was formulated as a mixed integer nonlinear programming model that minimized the total production operating cost and start-up cost. Due to the NP-hardness of the problem, an improved par-ticle swarm optimization (PSO) algorithm with a new velocity updating formula was developed to solve the problem approximately. Computational experiments on randomly generated instances were carried out to eval-uate the performance of the model and the algorithm's effectiveness. Compared with the commercial solver CPLEX, the improved PSO can obtain high-quality schedules within a much shorter running time for all the instances.     

Volatilisation of trace elements for coal–sewage sludge blends during their combustion☆

The influence of sewage sludge addition on the volatility of 37 trace elements (Ag, As, Au, B, Ba, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, Hf, Hg, La, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Tl, U, V, Y, Zn, Zr) during coal combustion was studied. For this purpose, a bituminous coal from the Asturian Central Basin and sewage sludge treated with Ca(OH)₂ and FeCl₃, as well as 10 and 50 wt% sludge–coal blends were used. Combustion experiments were performed in a laboratory electric furnace at 800, 900, 1000 and 1100 °C. The results have confirmed that the high Cl contents of the sludge can produce a pronounced effect on the volatilisation of some trace elements (Ag, Cd, Cs, Cu, Li, Pb, Rb and Tl) due to the probable formation of volatile chlorides, while the high CaO concentrations increase the retention of some elements in ash as As, Se and Te. The above opposite effects of Cl and CaO on trace element volatilisation were generally inappreciable for the 10 wt% blend, while they were more significant, but not as noticeable as expected, for the 50 wt% blend.     

Interactions between Bacteria And Aspen Defense Chemicals at the Phyllosphere – Herbivore Interface

Plant- and insect-associated microorganisms encounter a diversity of allelochemicals, and require mechanisms for contending with these often deleterious and broadly-acting compounds. Trembling aspen, Populus tremuloides, contains two principal groups of defenses, phenolic glycosides (salicinoids) and condensed tannins, which differentially affect the folivorous gypsy moth, Lymantria dispar, and its gut symbionts. The bacteria genus Acinetobacter is frequently associated with both aspen foliage and gypsy moth consuming that tissue, and one isolate, Acinetobacter sp. R7-1, previously has been shown to metabolize phenolic glycosides. In this study, we aimed to characterize further interactions between this Acinetobacter isolate and aspen secondary metabolites. We assessed bacterial carbon utilization and growth in response to different concentrations of phenolic glycosides and condensed tannins. We also tested if enzyme inhibitors reduce bacterial growth and catabolism of phenolic glycosides. Acinetobacter sp. R7-1 utilized condensed tannins but not phenolic glycosides or glucose as carbon sources. Growth in nutrient-rich medium was increased by condensed tannins, but reduced by phenolic glycosides. Addition of the P450 enzyme inhibitor piperonyl butoxide increased the effects of phenolic glycosides on Acinetobacter sp. R7-1. In contrast, the esterase inhibitor S,S,S,-tributyl-phosphorotrithioate did not affect phenolic glycoside inhibition of bacterial growth. Degradation of phenolic glycosides by Acinetobacter sp. R7-1 appears to alleviate the cytotoxicity of these compounds, rather than provide an energy source. Our results further suggest this bacterium utilizes additional, complementary mechanisms to degrade antimicrobial phytochemicals. Collectively, these results provide insight into mechanisms by which microorganisms contend with their environment within the context of plant-herbivore interactions.     

Equation oriented method for Rectisol wash modeling and analysis☆

Rectisol process is more efficient in comparison with other physical or chemical absorption methods for gas pu-rification. To implement a real time simulation of Rectisol process, thermodynamic model and simulation strat-egy are needed. In this paper, a method of modified statistical associated fluid theory with perturbation theory is used to predict thermodynamic behavior of process. As Rectisol process is a highly heat-integrated process with many loops, a method of equation oriented strategy, sequential quadratic programming, is used as the solver and the process converges perfectly. Then analyses are conducted with this simulator.     

CFD-based optimization and design of multi-channel inorganic membrane tubes☆

As a major configuration of membrane elements,multi-channel porous inorganic membrane tubes were studied by means of theoretical analysis and simulation.Configuration optimization of a cylindrical 37-channel porous inorganic membrane tube was studied by increasing membrane filtration area and increasing permeation efficiency of inner channels.An optimal ratio of the channel diameter to the inter-channel distance was proposed so as to increase the total membrane filtration area of the membrane tube.The three-dimensional computational fluid dynamics(CFD) simulation was conducted to study the cross-flow permeation flow of pure water in the 37-channel ceramic membrane tube.A model combining Navier–Stokes equation with Darcy's law and the porous jump boundary conditions was applied.The relationship between permeation efficiency and channel locations,and the method for increasing the permeation efficiency of inner channels were proposed.Some novel multichannel membrane configurations with more permeate side channels were put forward and evaluated.     

Non-isothermal crystallization kinetics of polypropylene and hyperbranched polyester blends☆

Polypropylene (PP) with different contents of the second generation hyperbranched polyester (HBP) is prepared by melt blending method. The non-isothermal crystallization kinetics of PP and PP/HBP blend...     

Anaerobic biodegradation of RDX and HMX with different co-substrates☆

Simulated wastewater of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex-trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation. With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1%and 98.5%was achieved for RDX and HMX, respectively, after treatment for 7 days. When so-dium acetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degrada-tion. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A wel-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.     

Isothermal and nonisothermal crystallization kinetics of bio-sourced nylon 69☆

Bio-sourced nylon 69,one of promising engineering plastics,has a great potential in developing sustainable technology and various commercial applications.Isothermal and nonisothermal crystallization kinetics of nylon 69 is a base to optimize the process conditions and establish the structure–property correlations for nylon 69,and it is also highly bene ficial for successful applications of nylon products in industry.Isothermal and nonisothermal crystallization kinetics has been investigated by differential scanning calorimetry for nylon 69,bio-sourced even–odd nylon.The isothermal crystallization kinetics has been analyzed by the Avrami equation,the calculated Avrami exponent at various crystallization temperatures falls into the range of 2.28 and 2.86.In addition,the Avrami equation modi fied by Jeziorny and the equation suggested by Mo have been adopted to study the nonisothermal crystallization.The activation energies for isothermal and nonisothermal crystallization have also been determined.The study demonstrates that the crystallization model of nylon 69 might be a twodimensional(circular)growth at both isothermal and nonisothermal crystallization conditions.Furthermore,the value of the crystallization rate parameter(K)decreases signi ficantly but the crystallization half-time(t1/2)increases with the increase of the isothermal crystallization temperature.To nonisothermal crystallization,the crystallization rate increases as the cooling rate increases according to the analysis of Jeziorny's theory.The results of Mo's theory suggest that a faster cooling rate is required to reach a higher relative degree of crystallinity in a unit of time,and crystallization rate decreases when the relative degree of crystallinity increases at nonisothermal crystallization conditions.     

Pyrolysis characteristics and kinetics of biomass residuals mixtures with lignite☆

Biomass residues in the Mediterranean region come mainly from agricultural and agro-industrial activities and forest byproducts. The paper presents the results of kinetic parameters and main devolatilisation characteristics of three biomass materials, when these are used either alone or in conjunction with Greek lignite. Namely, olive kernel, forest and cotton residues were pyrolysed in a thermogravimetric analyser, under dynamic conditions. The effect of material particle size and heating rate was investigated both on the pyrolysis behavior and reaction kinetics, over the temperature range of 25–850 °C. Furthermore, experiments with blends of lignite and biomass were conducted under the same conditions at the lower heating rate. The biomass materials presented higher thermochemical reactivity than lignite. Their decomposition was successfully modeled by three first-order independent parallel reactions, describing the degradation of hemicellulose, cellulose and lignin. No significant influence of the particle size was detected, both on the devolatilisation characteristics and kinetics. The effect of the heating rate on the pyrolysis behavior was more pronounced for biomass materials rather than lignite. A comparison between slow and fast heating rate tests reveals a small displacement of the DTG profiles to higher temperatures. It was concluded that such ‘solid bio-fuels’ could support the combustion of poor coals, because of the faster and in much higher quantity release of volatile compounds.     

Rheological and drag reduction properties of hydroxypropyl xanthan gum solutions☆

Hydroxypropyl xanthan gum (HXG) was prepared from xanthan gum (XG) and propylene oxide under alkaline condition. Rheological and drag reduction properties of different concentrations of aqueous HXG and XG solution were studied. The micro-structure network of HXG and XG solutions was investigated by Cryo-FESEM. The re-sults showed that HXG and XG solutions could exhibit shear thinning property. The apparent viscosity of 6 g·L?1 HXG solution was 1.25 times more than that of 6 g·L?1 XG solution. The storage modulus G′and the loss modulus G″of HXG solutions were greater than those of XG solutions, and thixotropic and viscoelastic prop-erties were more significant in HXG solutions. The HXG and XG solutions reduced the pressure drop of straight pipe, and the maximum drag reduction of 1 g·L?1 HXG and XG in smooth tube reached 72.8%and 68.1%, respec-tively. Drag reduction rate was increased as the concentration increased. The HXG solution may become a new polymeric drag reducer.     

Determination and Correlation of Solubility of Nonivamide in Different Solvents☆

The solubility of nonivamide in dimethyl sulfoxide, methanol, acetone, ethyl acetate, methyl tert-butyl ether, ace-tonitrile, n-hexane and water over the temperature range of 293.2 K to 323.2 K was mea...     

Adaptive partitioning PCA model for improving fault detection and isolation☆

In chemical process, a large number of measured and manipulated variables are highly correlated. Principal com-ponent analysis (PCA) is widely applied as a dimension reduction technique for capturing strong correlation un-derlying in the process measurements. However, it is difficult for PCA based fault detection results to be interpreted physical y and to provide support for isolation. Some approaches incorporating process knowledge are developed, but the information is always shortage and deficient in practice. Therefore, this work proposes an adaptive partitioning PCA algorithm entirely based on operation data. The process feature space is partitioned into several sub-feature spaces. Constructed sub-block models can not only reflect the local behavior of process change, namely to grasp the intrinsic local information underlying the process changes, but also improve the fault detection and isolation through the combination of local fault detection results and reduction of smearing effect. The method is demonstrated in TE process, and the results show that the new method is much better in fault detection and isolation compared to conventional PCA method.     

Char characterisation and its application in a coal burnout model☆

In this study, char image analysis techniques have been employed to investigate the morphology of chars obtained from a Drop-Tube furnace. Char image analysis results have been incorporated as inputs to a char burnout model based on Hurt's CBK model. It has been observed that the char combustion rate was strongly affected by char structural parameters and the inclusion of char morphology has led to a better prediction of char burnout. It has also been suggested by the model that the inclusion of ash inhibition overestimates the resistance attributed by ash film and the consideration of ash film resistance should be undertaken in a different way to give a better prediction at the later stages of char combustion.