Showing papers in "CIESC Journal in 2015"

Molecular simulations of adsorption characteristics of clay minerals in shale

Abstract: The adsorption and desorption characteristics of shale is very important for the development of shale gas. For the sake of thorough understanding the adsorption mechanism in micro-scale view for clay minerals in the shale, three molecular models including illite, montmorillonite and kaolinite were established by using molecular simulation software Material Studio, the grand canonical Monte Carlo(GCMC) method was used for the calculation of isotherm adsorption capacity and adsorption heat. At the same temperature and pressure, isotherm adsorption capacity of CH4 in three clay minerals was in the sequence below: illitemontmorillonitekaolinite. With the increase of pressure, the isotherm adsorption capacity of CH4 in three clay minerals increased, and CH4 adsorption in illite, montmorillonite was more sensitive to pressure changes than that in kaolinite. The heat of adsorption of three clay minerals were less than 42 k J·mol-1, proving that adsorption of CH4 was physical adsorption. With the increase of temperature, the adsorption heat of CH4 reduced and the isotherm adsorption capacity of CH4 was decreased, suggesting that high temperature was disadvantageous to adsorption of CH4.

Chemical catalytic performance on nitrate removal of simulated groundwater

Abstract: In this paper, the nitrogen removal efficiency and mechanism by the chemical catalytic particle carrier, i.e., the self-made active catalytic solid particle carrier and its influence factors such as HRT, initial p H and the quality of influent were studied and analyzed. The reaction kinetic model was established. The result showed that the nitrogen removal by self-made carrier is 3 order reaction and the initial concentration of ammonia in water had inhibitory effect on the reaction. Nitrogen removal rate reached 88.7% when HRT was 2 h, and was up to 90% no matter in acidic, neutral or alkaline conditions. Compared to normal zero-value iron or ferric carbon micro electrolysis, the chemical catalysis particle carrier was more efficient and had no particular requirement on influent p H.

Online dynamic Gaussian process regression for dynamic liquid level soft sensing of sucker-rod pumping well

Abstract: In practice, dynamic fluid level is traditionally measured onsite by using the acoustic method. This method, however, has its limitation in determining real-time dynamic liquid level. Determining real-time dynamic liquid level by analyzing the measured dynamometer card has poor precision. Model aging happens as time goes by with the data driven soft sensing modeling method. An incremental dynamic Gaussian process regression(IDGPR) was presented for the soft sensing modeling in order to realize real-time determination of dynamic liquid level. At the beginning a basic soft sensing model based on dynamic Gaussian process regression was established. After the model was put into application, it could be updated on-line through an incremental learning method. The model could be constantly adaptable to the change of operating condition and precisely predict dynamic liquid level. The application result in the oil field showed that the proposed soft sensing model achieved high prediction precision and good generalization ability, meeting engineering requirement.

Visual experiment on evolution of flow pattern of R124-DMAC bubble absorption process in vertical tube

Abstract: Through constructing a visual experiment platform of bubble absorption heat and mass coupled transfer characteristics in the vertical tube, the flow pattern characteristic and distribution regularity of bubble absorption process on R124/DMAC(2-chloro-1,1,1,2,-tetrafluoroethane / N', N'- dimethylacetamide) as working medium are studied. The result shows that the flow pattern characteristic and distribution regularity are influenced by the refrigerant vapor flow rate, absorption solution flow rate and its inlet temperature. Under large refrigerant vapor flow rate and high solution inlet temperature conditions, three kinds of flow patterns of churn flow, slug flow and bubble flow can be simultaneously observed in the bubble absorption tube. Under the condition which the vapor is completely absorbed in the absorption tube, the height of churn flow is no more than half of the total absorption height, while the height of slug flow is no more than 2/5 of the total absorption height. The rest of the absorbing height is occupied by bubble flow.

Effect of diameter and length of vortex finder in water-sparged aerocyclone reactor on its mass transfer performance in air stripping of ammonia

Abstract: Water-sparged aerocyclone(WSA) is a new gas-liquid mass transfer equipment, which takes the advantage of coupling effect of air cyclone and liquid jet fields. In order to improve its mass transfer performance and establish design principles, the effect of diameter(De) and length(S) of the vortex finder in the WSA on its mass transfer performance and air pressure drop in air stripping of ammonia was investigated and optimized. A new concept, mass transfer efficiency per gas pressure drop, pη, and its calculation equation were put forward. The WSA with smaller De and longer S showed higher mass transfer efficiency than that with larger De and shorter S in air stripping of ammonia. However, this kind of WSA had higher air pressure drop, which would consume more energy. Calculation of pη, which was a comprehensive indicator considering energy consumption and mass transfer efficiency, showed that it increased with the increase of De/D and S/H,but it deceased a little when S/H increased from 0.71 to 0.93. The optimal De/D and S/H should be 0.43 to 0.53 and 0.70, respectively. These results could be used as a guide for the design of WSA with good mass transfer performance.

Preparation of magnetic CuO-Bi_2O_3/ Fe_3O_4-SiO_2-MgO catalyst and its catalytic performance for formaldehyde ethynylation

Abstract: Magnetic Cu O-Bi2O3/Fe3O4-Si O2-Mg O catalysts with different Cu content were prepared by using impregnation and coprecipitation methods. The obtained catalysts were characterized by atomic emission spectrometer(ICP-AES), N2 absorption, X-ray diffraction(XRD), H2 temperature-programmed reduction(H2-TPR) and vibrating sample magnetometer(VSM). Their catalytic performance for formaldehyde ethynylation was evaluated. The results indicated that preparation method showed a great influence on the Cu O station in catalysts,thus,on the performance for formaldehyde ethynylation reaction. Compared with the catalysts prepared by impregnation, the Cu O-Bi2O3/Fe3O4-Si O2-Mg O catalysts prepared by co-precipitation method showed higher Cu O dispersion and better reducibility, so had better catalytic activity and selectivity. Moreover, Cu content was another important factor affecting catalyst activity. With Cu content increasing, the catalyst activity increased gradually. In the present work,30%(mass) Cu loading catalyst prepared by co-precipitation method showed the highest catalytic activity. In addition, this catalyst was of good superparamagnetism and stability, so easy separated by external magnetic field for reuse. After six cycles, its stability was much better than non-paramagnetism Cu O-Bi2O3/Si O2-Mg O catalyst.

Numerical simulation of surface renewal frequency on vertically rotating disc

Abstract: The surface renewal in rotating disc reactor was investigated by using CFD. The liquid film surface renewal frequency was associated with the rate of film deformation. The spatial distribution of film surface renewal frequency was studied with the volume of fluid method. Based on the investigation of main factors influencing average renewal frequency, a correlation equation was presented. The difference of surface renewal frequency between free film and wall-bounded film was also investigated. The renewal frequency of the accelerating region was the fastest, about 150% faster than other regions and 75% faster than the average. An expression of renewal frequency was obtained. The renewal frequency of the free film was 40% faster than that of the wall-bounded film. The renewal frequency of the free film on round window was 34% faster than the fan-shaped free film, but the fan-shaped free film could intensify the wall-bounded film significantly.

Microbial fuel cell anode modified by chemical oxidation

Abstract: Oxidants of nitric acid and acidic potassium dichromate were used to modify anode carbon cloths. Modification was completed by first putting the carbon cloth into nitric acid or acidic potassium dichromate at a given temperature, soaking for 30 min and then rinsing with de-ionized water until no variation in pH and finally putting into a vacuum dryer, drying for 12 h. Fourier transform infrared spectroscopy measurements indicated that many hydroxyls and carboxyls were attached on the carbon cloth surface after modification. SEM results showed that the surface of carbon cloth became rougher than the unmodified one. In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements demonstrated that both modified anodes had excellent electrochemical properties. Using the modified carbon cloths as microbial fuel cell (MFC) anodes respectively, such MFCs yielded maximum power densities of 291.11 mW·m −2 and 438.08 mW·m −2 , 21% and 82% higher than that of the MFC with unmodified carbon cloth anode respectively.

Characterization of morphology, structure and composition of soot particles from biomass fuel

Abstract: Emulsified biomass fuels were prepared via micro-emulsified technology. The morphology, structure and composition of soot particles formed from combusting three kinds of micro-emulsified biomass fuel(MEBF) BS10, BS20 and BS30 in which the content of refined biomass oil were 10%(mass), 20%(mass) and 30%(mass) respectively were characterized using a series of surface analysis tools, and compared with diesel soot particles(DS). The results showed that the morphology of primary soot particles for all three kinds MEBF is spherical and their aggregates are all chain-likes. The average primary particle diameter is smaller for BS20(32 nm) than for DS(38 nm), BS10(39 nm) and BS30(37 nm), while the graphitization degree of soot particles is higher for BS30 than for DS, BS10 and BS20. Besides, the contents of C O and C—O—C functional groups on the surfaces of BS20 particles are higher than those of others. These phenomena possibly were ascribed to the variances of oxidization degree of fuels which involved different oxygen-rich components.

Gas-solid heat transfer characteristics in vertical tank for sinter waste heat recovery

Abstract: With a homemade gas-solid heat transfer experimental setup, an experimental study was conducted on gas-solid heat transfer characteristics in a packed bed with sinter particles The results show that the main factors affecting the gas-solid heat transfer process in sinter bed layer are gas superficial velocity and sinter particle diameter With the increase of gas superficial velocity and the decrease of sinter particle diameter, the gas-solid heat transfer coefficient increases in the sinter bed For given gas superficial velocity and sinter particle diameter, higher sinter particle temperature in the bed gives higher gas-solid heat transfer coefficient and lower Nusselt number of heat transfer Due to the large calculation error, the existing prediction correlations are not suitable for the gas-solid heat transfer process in sinter bed Based on the method of dimensional analysis, an experimental correlation for describing the gas-solid heat transfer characteristics in sinter bed is obtained by fitting the experimental data, and its mean deviation from experimental data is 422%, giving good prediction

Visualized experiment on dynamic thermal behavior of phase change material in metal foam

Abstract: Latent heat thermal energy storage technology is a promising option for future cost reduction in parabolic trough power system, however, low thermal conductivity of phase change material(PCM) is the major shortage leading to large temperature difference between heat transfer surface and solid-liquid interface of the PCM, and low energy storage rate. A charging experimental system was set up for testing the dynamic thermal behavior of phase change material in metal foam. Paraffin wax is used as PCM and its thermal properties were determined with differential scanning calorimetry(DSC). Metal foam was made of red copper. The sample of PCM-foam composite with semi-circular slot was placed inside a transparent cuboid Plexiglas enclosure, and a copper tube with the same radius as the semi-circular slot was in close bonding with the PCM-foam composite. High temperature water flowed through the copper tube as the heat transfer fluid(HTF) heating the composite material. The temperature field and melting process of PCM at pore size were studied using appropriate thermocouple and high definition camera. Thermal characteristics, including temperature profiles and position of solid/liquid interface were investigated and recorded, and the effects of heating temperature and flow rate of HTF on temperature uniformity and melting rate were documented and discussed. Metal foam could effectively improve heat transfer performance of PCM and decrease charging time Temperature difference was smaller and heating flux was larger in the composite than those in pure paraffin.

Effects of chemical fractionation analysis on physical and chemical structures of biomass char

Abstract: Chemical fractionation analysis is widely used to study the effect of alkali and alkaline earth metal(AAEM) species on the reactivity of biomass char. The influence of chemical fractionation analysis on the physical and chemical structures of biomass char was investigated in this study. The physical structures of biomass char were studied by the mercury porosimetry and scanning electron microscopy(SEM). The results showed that the influence of chemical fractionation analysis on the porosity and surface morphology of the biomass char was apparent. However, the effect of chemical fractionation analysis on the specific surface area of biomass char could be ignored. X-ray photoelectron spectroscopy(XPS) and Raman were used to identify the O-containing functional groups and the aromatic ring structures in the biomass char, respectively. The results indicated that the changes of the oxygen containing functional groups were little during the chemical fractionation analysis. The influence of the chemical fraction analysis on the aromatic ring structures could be ignored. During the chemical fractionation analysis, both NH4 Ac and HCl could change the cross-linking structures of biomass char.

Effect of thermodynamic properties on non-equilibrium condensing flow of wet steam

Abstract: Wet steam condensation flows presents a high degree of non-equilibrium characteristics. At present, the condensation parameters are obtained by using semi-empirical formula, while heat transfer temperature difference and coupling problems are seldom considered. A simple condensation nucleation model and droplet growth model for non-equilibrium phase change of wet steam is established in this study. In order to calculate the wet steam parameters and condensation shock wave distribution of non-equilibrium condensation flows, the second-order TVD scheme is adopted. The influence of thermodynamic properties of inlet wet steam on the non-equilibrium condensation flow is examined, the influence of inlet pressure on the condensation characteristic is discussed, and various patterns of inlet subcooled temperature on nucleation rate, droplet number, condensation shock are summarized. It is found that as inlet pressure increases, the condensing location moves upstream. At a lower import subcooled temperature, the condensing position moves downstream. At higher Mach number, nucleation occurs. As the import subcooled temperature increase, the wetness of non-equilibrium condensation phase transition will be higher. After the onset of condensation shock, steam expands continuously along the nozzle and the flow pattern is similar to isentropic flow.

Chemical structure analysis of oil shale kerogen

Abstract: Five different oil shale kerogens were analyzed with advanced testing techniques(XRD, 13 C NMR and FT-IR) to obtain important structural information The long-range disordered state of aggregation was also confirmed by XRD Using 13 C NMR spectroscopy, 18 characteristic parameters of carbon skeleton structure were obtained Detailed information about the chemical structure of kerogen was obtained through verifying the results of 13 C NMR experiments with the qualitative analysis of kerogen groups made by FT-IR technique The aliphatic structure of oil shale kerogen was up to 60%—90%, with the methylene carbon occupying the dominant position of 77%—90%, and most of the aliphatic structure were straight-chain while less alicyclic or branched chain In addition to Huadian oil shale with a monocyclic aromatic carbon structure, the other four oil shale kerogens were co-existing monocyclic and polycyclic rings, with the latter mainly peri-condensed The oxygen structure was C O(alcohol, phenol, ether) and C O, and carboxyl class was more than carbonyl class C O More C O in kerogen was due to a low degree of metamorphism, while a high degree of metamorphism resulted in more C O

Numerical simulation and experimental research on novel heat transfer surface

Abstract: Confronted with low-quality heat source, such as high ash contents, discontinuity and instability in waste heat recovery, innovations are required in the structure of typical heat transfer surface. In this paper a novel structure with rhombus heat transfer surface was presented. This heat transfer surface was efficient in both waste heat recovery and ash blowing. In the heat transfer process, the new heat transfer surface showed similar performance with the staggered tubes arrangement, for instance enhanced heat transfer and relatively large fluid flow resistance and higher convection heat transfer coefficient in the shell side. In the dust blowing process, this surface performed like the aligned tubes arrangement, which was easy to clean and efficient in dust blowing. Numerical simulation and experimental investigation were conducted to obtain heat transfer and flow performance of the new structure. Both numerical and experimental results indicated that the new structure met basic requirements of waste heat recovery, achieving highly efficient heat transfer along with convenience of dust cleaning and descaling.

Improvement of acetic acid tolerance of Saccharomyces cerevisiae by overexpressing glutaredoxin encoding gene GRX5

Abstract: Fuel ethanol production using renewable cellulosic materials has attracted widespread attention by researchers. However, acetic acid released from the pretreatment process exerts severe inhibition on yeast cell growth and ethanol fermentation. Therefore, improvement of acid tolerance of industrial Saccharomyces cerevisiae benefits efficient cellulosic ethanol production. In this work, glutaredoxin encoding gene GRX5 was overexpressed in S. cerevisiae, and it was found that the GRX5 overexpression strain grew better than that of the control strain in the plates containing 5 g·L1 acetic acid. When ethanol fermentation in the presence of 5 g·L1acetic acid was evaluated, it was found that the GRX5 overexpression strain consumed all glucose in the broth within 48 h, 12 h shorter than that of the control strain. Ethanol productivity of the GRX5 overexpressed strain was determined to be 0.897 g·L1·h1, with a 28.5% increase than that of the control strain. Analysis of the key metabolites showed that the GRX5 overexpression strain produced higher concentration of trehalose and glycerol, which might explain its improved cell viability in the presence of acetic acid stress.

p-Nitrophenol removal using soil aquifer treatment system

Abstract: p-Nitrophenol(PNP), a toxic and recalcitrant organic compound, has been widely used as an intermediate for preparing phosphororganic insecticides, medications, explosives and synthetic dyes Control and removal of PNP is always a research focus Soil aquifer treatment(SAT) system is a widely used wastewater treatment system with better efficiency and low cost, which is also used for artificial aquifer recharge The present study investigated PNP removal in the SAT system under abiotic and bio-augmentation conditions using 1D columns PNP was removed well in both cases Soil adsorption was the main mechanism under abiotic condition The depth of soil for effective treatment was 60 cm, and removal rates reached 10% for coarse, medium-coarse and fine sand columns Under bio-augmentation condition, PNP removal rate with addtional bio-degradation increased to 885%

Effect of C/N on performance of AAO-BAF process

Abstract: Combining anaerobic-anoxic-oxic reactor with an external nitrification biological aerated filter, the AAO-BAF process was used to treat domestic wastewater Adjusting the influent COD concentration from 211 to 675 mg·L-1, the effect of carbon-nitrogen ratio(C/N) on the performance of the AAO-BAF process was investigated A low or high influent organic concentration had significant effect on the nutrients removal efficiency due to the deficient phosphorus release or nitrate competition in the anoxic zones of the AAO reactor between DPAOs and ordinary heterotrophic organisms When C/N was between 4 and 7,the average removal efficiencies of COD, TN and PO43-could reach more than 86%, 78% and 90% respectively Large quantity of residual volatile fatty acid(VFA)would be transferred into the anoxic zones when C/N was very high(such as 95), which would cause rapid consumption of NO-3 by ordinary heterotrophic organisms rather than denitrifying phosphorus accumulating organisms(DPAOs)

Flowing deviation behavior of plastic melt during micro injection molding process

Abstract: The migration phenomenon of the melt flow front of multi-cavity micro injection molding process within the cavity is observed and analyzed using temperature measuring system equipped of integration of thermocouple sensor and visualization holographic tracer technique. The experimental results show that in the injection rate of 140—220 mm·s-1, the plastic melt front in the main runner is "U flow state", while it is upper offset within secondary runner; in the injection rate of 10—70 mm·s-1, the plastic melt front in the main runner is "fountain" flow state, while it is down offset within secondary runner; and in the injection rate of 80—120 mm·s-1, the plastic melt fronts within both main and secondary runners have no obvious offset. The results indicate that the injection speed is different during the micro injection molding, leading to various shear heat and also melt front offset. Therefore, a nonequilibrium flow coefficient λ is introduced to determine the flow of the melt front and offset.

Treatment of piggery wastewater with low C/N ratio and mechanism for denitrification in wood-packed-bed A/O process

Abstract: Manure-free piggery wastewater is low in COD but high in 4NH+ concentration with a COD-to-TN(C/N) ratio less than 1. In order to removal nitrogen from the wastewater efficaciously, a wood-packed-bed A/O process with four compartments was constructed and its performance in pollutant removal was evaluated, especially the denitrification. The reactor was operated at HRT 18.7 h and 32℃ with an internal recycle ratio of 200% and DO 1.5 mg·L-1 in the last compartment. The treatment process was started up with diluted raw wastewater in which COD/TN ratio was regulated to about 3.9. When the process performed steady, the dilution rate of the raw wastewater was decreased stage by stage, synchronizing with C/N ratio. When the process was steady in the last stage even feeding the raw wastewater with a high 4NH+ of about 307.7 mg·L-1 and a COD/TN ratio as low as 0.47, the removal of COD, 4NH+ and TN was averaged out about 66.5%, 93.6% and 89.0%, respectively. A load removal of TN above 0.22 kg·m-3·d-1 was obtained. The four compartments had illustrated difference in pollutant removal with a total COD removal of about 78.3% in the front three anaerobic compartments and a TN removal of about 73.1% in the last aerobic compartment. TN removal in the reactor was mainly attributed to the shortcut nitrification-denitrification process with the packed wood as the internal carbon source.

Azo-hydrazone tautomerism of azo dyes

Abstract: There exists azo-hydazone tautomerism for azo dyes, which consists of two concepts. Both azo form and hydrazone form are a pair of isomers, but exhibit different performance due to their structures. They can transform into each other under appropriate conditions. To confirm their isomeric structure is the base for a study of the relationship between the structure and properties. There are two misleading concepts prevailing in dyestuff industrial and academic circles. The former insists that azo form and hydrazone form co-exist with no difference between these two isomers, whilst the latter believes that they can transform into each other at any moment. An investigation into the tautomers transformation was conducted and the relationship between their structures and properties was discussed. Azo form and hydrazone form of an azo compoun possess different UV-Vs spectra, chemical properties and fastness. Usually it takes one of the tautomers as the stably-existed status, which determines its color and dyeing performance. Azo form or hydrazone form only can be transformed into each other under specified conditions, which depended on their structures and environmental conditions, such as temperature, solvents, p H of media, etc. The confirmation methods of these tautomeric structure by IR,Raman, NMR, MS spectra and X ray differential spectra were introduced.

Distribution properties and movement of particles in gas-solids flow passing through liquid bath

Abstract: In order to study the flow characteristic of gas-liquid-solids three-phase in the process of gas-solids two-phase flow passing through the liquid bath, an experimental platform and a numerical simulation platform based on the Euler-Lagrange method were established respectively to conduct the studies on three-phase flow and particles movement. The distribution characteristics and the movement of three typical particle sizes were obtained, such as 5—15 μm, 80—110 μm and 380—530 μm. The results of experiment were consistent with the results of numerical simulation. A multi-peak distribution of particle concentration existed in the liquid bath along the axial and radial directions. The particles of 5—15 μm in diameter were more easy to follow gas, and their distribution was more uniform. The particles of 380—530 μm in diameter were more difficult to follow gas, and their distribution was mainly concentrated at the bottom of the liquid bath. The increase of static submerged depth of downcomer outlet made the concentration distribution of particles more smoothly in the liquid bath.

Preparation of oil-in-water nanoemulsions used for protection of shale gas reservoirs

Abstract: There is a very prominent problem of water sensitive damage and liquid trap damage caused by drilling fluid during the exploitation process of shale gas reservoirs. A two-step dilution method for preparation of oil-in-water nanoemulsions used for the protection of shale gas reservoirs was introduced. The nanoemulsion could have small droplet sizes and fine dispersity. Selecting mixtures composed of Gemini hyamine surfactant GTN, Tween80 and n-butyl alcohol as surfactant component(referred to as S+A), the effects of mass concentration of Na Cl on the properties of Na Cl solution/(S+A)/n-octane systems was studied. The influence of the phase inversion temperature, emulsification methods and the structure of microemulsion on the droplet size of nanoemulsion was investigated. The instability mechanism of nanoemulsion system was researched. The results showed that increasing the concentration of Na Cl could effectively change the microemulsion structure of Na Cl solution/(S+A)/n-octane system, decrease the phase inversion temperature significantly and improve the emulsification efficiency. Oil-in-water nanoemulsions prepared by two-step dilution method had the smallest droplet size and the best dispersity at Ros= 7:3 when the emulsification temperature approached the phase inversion temperature. The mechanism of instability can be attributed to Ostwald ripening in Na Cl solution/(S+A)/n-octane system. Nanoemulsion had good performance for protecting shale gas reservoirs.

Comparison of dissolution and regeneration structure of collagen with two ionic liquids: [BMIM]Cl and [BMIM]Ac

Abstract: 1-butyl-3-methylimidazolium acetate([BMIM]Ac) was synthesized from 1-butyl-3-methylimidazolium chloride([BMIM]Cl) via the ion exchange method. These imidazolium ionic liquids(ILs) were used as solvents to dissolve collagen fibers. The solubility and the change of collagen structure as well as thermal stability after dissolution and regeneration from ILs were investigated. Athough collagen fibers could be dissolved in both CH3COO- and Cl- imidazolium ionic liquids, the dissolution characteristics were quite different. Compared with [BMIM]Cl ionic liquid, [BMIM]Ac was more advantageous to achieve a collagen solution with high concentration and good fluidity at a lower temperature, especially in retaining the integrity of collagen triple helix. FTIR, UV, XRD, CD and TG analysis were used to characterize the structure and properties of collagen before and after regeneration, and the results revealed that collagen chemical structure showed almost no change, but with slightly lower thermal stability and integrity of triple helix.

Reactor system switch strategy for acetylene hydrogenation process

Abstract: Acetylene hydrogenation is an important device in the ethylene plant Assume that the reaction kinetic and deactivation model are known, we optimize the acetylene convert loads between two reactors in series The result shows that the H2/C2H2 ratio of the lead reactor should be less than 10 and the one in guard reactor can increase from 19 to 35 according the requirement After taking account of the operation cost and product price, we further optimize the reactor switch strategy when the acetylene convert load is optimal In order to get a net gain of ethylene, the lead reactor should run in 14 months while the guard one should run in 4 months

Pressure response and phase transition in process of CO_2 pipeline release in industrial scale

Abstract: Three groups of CO2 pipeline release experiments were performed using an industrial scale(256 m long, 233 mm id) instrumented pipeline with CO2 pre-discharge phase of gas phase, gas-liquid phase and supercritical phase, respectively. The pressure response and the phase transition were recorded and analyzed in the process of CO2 pipeline release. The results showed that when the pressure wave front arrived, the pressure fall and stagnation appeared in the process of gaseous CO2 release. The phase of CO2 in the pipeline during the gaseous CO2 release was mainly in gas state, but the temperature at the end pipe decreased sharply, leading to the formation of gas-liquid homogeneous CO2. The decompression multiple reflection led to multiple pressure fall sharply and rebound in the release of gas-liquid CO2. Gas-liquid layered CO2 transformed to gas-liquid homogeneous CO2 in the phase transition process of gas-liquid CO2, and then the gas-liquid homogeneous CO2 at the top of pipeline transformed to the gas CO2 and consequently the bottom. The pressure fall sharply and rebound appeared near critical region in the release of supercritical CO2. When the pressure passed through the critical pressure line, the pressure change rate could be stagnation and slow down. The discharge of the supercritical CO2, gas-liquid homogeneous CO2 and gas CO2 appeared in the process of supercritical CO2 release.

Numerical simulation of droplet generation in crossing micro-channel

Abstract: Micro-droplet formation in the crossing micro-channel was numerically simulated by the 3D VOF model Three flow regimes to generate droplet with monodispersity(squeezing, dripping and jetting) and other regimes(turbulent jetting, nodular flow, tubular flow, slip flow) were obtained The simulation results agreed well with experiment observations, which validated the numerical model The flow regimes were mainly affected by flow rate, surface tension and viscosity of two phases With increasing flow rate of the continuous phase, droplet size would decrease and generation frequency would increase, whereas the effect of flow rate of the disperse phase was the opposite Surface tension and viscosity of the continuous phase played a leading role under the conditions of high and low Ca number of the continuous phase, respectively When Ca number was low, droplet size decreased in the squeezing and dripping regimes and increased in the jetting regime with decreasing surface tension, while generation frequency shows the reverse changing tendency compared with droplet size When Ca number of the continuous phase was high, however, droplet size decreased with increasing the viscosity of the continuous phase, while generation frequency changed inversely In addition, contact angel had little effect on the squeezing regime, but droplet could not be generated in the dripping and jetting regimes when contact angel decreased

Roasting process and non-isothermal kinetics for sulfating roasting of coal fly ash

Abstract: Roasting process with sulfuric acid plays an important role in extracting Al2O3 from coal fly ash The results indicate that Al conversion rate increases with appropriately increased acid concentration, the mass ratio of acid to ash and the roasted temperature, while the effect of roasted time is relatively small The Al conversion rate can reach 92%—93% at recommended processing parameters: sulfuric acid concentration 80%, acid-ash mass ratio 15:1, roasted temperature 270℃ and roasted time 60 min An analysis for TG/DSC and XRD data demonstrates that the roasting process can be divided to 3 steps: the first step is Al(HSO4)3 formation and water evaporation; the second the formation of Al(HSO4)3 and Al2(SO4)3·H2O, and the third Al2(SO4)3 formation from decompositions of Al2(SO4)3·H2O and Al(HSO4)3 The values of apparent activation energy for the three steps are 5261, 7411, and 9608 k J·mol-1 respectively, an activation energy average of values obtained by Kissinger and Ozawa methods Using the kinetics parameters estimated, such as activation energy, frequency factor, reaction order, three kinetic equations which correspond to three thermo-chemical reaction steps in the roasting process are established These fundamental data and theoretical guideline provided in this paper could be used for the process design and optimization of sulfuric acid roasting process to extract alumina from coal fly ash

Novel cationic UV-curable cathodic electrophoretic coatings with pendant amine salt

Abstract: N-Methyldiethanolamine(MDEA) bearing main chain tertiary amine and 7,12-dioxa-3,16-diaza-3,16-diethyl-5,14-octadecanediol(DDDOD) bearing pendant tertiary amine were used as the hydrophilic monomers, respectively to prepare polyurethane dispersions. Hydrophilcity of the two hydrophilic monomers was compared by the dispersibilities of the polyurethanes and mean diameters of the dispersions. The results showed that DDDOD had a better hydrophilcity than MDEA, revealing that hydrophilic monomer with pendant tertiary amine had a superior hydrophilic ability than that with backbone tertiary amine. Polyurethane was prepared by the reaction between DDDOD, poly-caprolaclone glycol(PCL) and isophorone diisocyanate(IPDI). UV-curable monomers were added into the polyurethane and dispersed together. The properties of the dispersions and films were studied. The conversion of carbon-carbon double bonds after UV-curing was analyzed.

Analysis of re-entrainment in process of gas-liquid filtration

Abstract: In long-distance transmission of natural gas, safe operation of compressor units is seriously affected by droplets entrained in natural gas. The characteristics of re-entrainment in gas-liquid filtration process of filter cartridges were investigated using liquid aerosol of di-ethyl-hexyl-sebacate(DEHS). The effects of filter material wettability and filtration velocity on re-entrainment were also evaluated experimentally. Re-entrainment could be observed in the process of filtration as filter cartridges only composed of coalescing layers. More droplets were entrained into the downstream due to re-entrainment and some large particles could be detected at the downstream. Cumulative efficiency decreased at the large particle size at steady state. Re-entrainment was affected by filter material wettability. Compared with non-wettable filter material, re-entrainment was more obvious on the surface of wettable filter material. To improve filtration efficiency, non-wettable filter material were more suitable for producing industrial filter cartridges at the same filtration velocity. As filtration speed increased from 0.1 m·s1 to 0.3 m·s1, higher filtration velocity led to less re-entrainment, and filtration performance of wettable filter cartridges were improved more significantly than that of non-wettable filter cartridges. Re-entrainment could be eliminated by adding drainage layer to filter cartridges.