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PD (partial discharge) is one of the most effective parameters to evaluate the insulation condition of power equipment. When PD happens, the optical signals will be emitted from the discharge sources. PD can be detected by measuring the optical signals. The PD optical method has electromagnetic immunity and especially suitable for the GIS (gas insulated switchgears) system which has a totally enclosure structure. At present, the related studies about development of optical sensors, optical detection of typical defects, and analysis of relationship between PD electrical and optical signals have been conducted in laboratory. However, the researches on propagation characteristics of PD optical signals are lack. In order to study the effects of propagation distance, GIS structure, receiving angle, and GIS component on the characteristics of optical signals induced by PD in GIS, a simulation model is built based on the size and structure of a physical GIS in this work. The photon amount and luminous flux detected by optical sensor under the condition of different distance, different GIS structure types, different positions of discharge source, and existing insulator with air hole are investigated. The results show that the photon amount and change rate of photon number will decrease with the increasing in distance between optical sensor and discharge source. the optical signals are the strongest when the PD source directly faces the detection sensor. The attenuation of optical signals is mainly caused by the hide of the GIS component when the detection angles change. With the increasing of voltage levels of GIS, the attenuation of optical signals is more obvious. The maximum change rate of photon number detected by the sensor in the L type GIS are about 61% of that in the line type GIS, which are 45% in the T type GIS. The related results can provide support for the installation of optical sensor and detection region of optical method.

Organic solvent nanofiltration (OSN) is a new membrane technology with many applications in pharmaceutical and fine chemicals development and manufacture, from laboratory through production scales. One application of particular industrial relevance is the ability to recover and recycle homogeneous catalysts, in particular asymmetric, organometallic, homogeneous transition metal catalysts. Industrial application of this group of catalysts is often limited due to the cost of applying these catalysts to single reactions and the subsequent product yield losses associated with removal of the catalyst from solution. OSN provides a technique that can maximise the value of the catalyst through catalyst recycle from one reaction batch to the next, whilst minimising the concentration of catalyst present in the reaction product. This contribution describes the development and demonstration of OSN catalyst recycle on an example catalytic system, the homogeneous, asymmetric hydrogenation of dimethyl itaconate (DMI) to...

Combined rapid gravity filtration and backwash models have been applied to simulate filtration and backwash cycles. The simulated results from the backwash model suggest that an optimum air flow rate exists to maximise particle removal efficiency in the backwash operation for a certain backwash system. The simulation of combined rapid gravity filtration and backwash models suggests that the filter shouldn't be completely cleaned up in the backwash and a certain amount of particles retained on filter grains after backwash can be beneficial for subsequent filtration runs. This is consistent with the experimental results in the literature.

A new filtration model has been developed to describe the entire three‐stage filtration run. The two‐stage assumption is applied for physical description of the rapid gravity filtration process. At the first stage of the filtration, previously deposited particles serve as collectors to improve particle removal efficiency and the detachment of deposited particles does not occur until the specific deposit reaches a certain transient specific deposit where the second stage starts. Particle detachment rate at the second stage is assumed to be a function of relative specific deposit and hydrodynamic conditions within filter media. The proposed filtration model has been applied to fit the data from one water treatment plant of Yorkshire Water (UK). The comparison demonstrates a good agreement between water treatment site data and the simulated results.

Based on the field-circuit equivalence concept, the equivalent circuit to analyze the voltage distribution of a 500-kV dc transmission-line voltage divider under impulse voltages has been developed. The hybrid finite-element analytical approach is applied to extract the capacitance and inductance parameters of the equivalent circuit, and the Milne method is used to solve this complicated circuit. The voltage distribution along the resistor coils of the divider under impulse voltages is calculated and its nonuniformity is discussed. The analysis results are in good agreement with the measurement results. The selection of capacitors parallel with the resistor turns to improve the voltage distribution along the resistor coils is studied, and the optimal selection of these capacitors is suggested.

This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD

It is essential to extract the stray parameters accurately and efficiently in analyzing impulse responses of a power apparatus. In this paper the stray capacitances and stray inductances of a 500-kV dc transmission-line voltage divider are extracted by the hybrid finite element-analytical approach, and the corresponding equivalent circuit for analyzing the impulse voltage response of the voltage divider is established. According to the discussion of the results of the extracted stray parameters of the voltage divider, reasonable simplification of the equivalent circuit of the voltage divider is made. In addition, the influence of the insulating housing and the electrical insulation oil on the stray capacitances of the voltage divider is discussed.

An approach coupling indirect boundary element method with charge simulation method to calculate the electric fields around the head of transmission tower and its composite insulators is presented. On the composite insulators, the indirect boundary element method is used, while on the transmission tower and the transmission lines, the charge simulation method is used. Therefore, both the heterogeneous medium such as the composite insulators and the filament metal structure such as the transmission tower and the transmission lines are considered all together. The electric field distribution around a 330-kV transmission tower and its composite insulators was analyzed. The method gives the possibility to model very complex geometries

In this paper, the electric-field distribution around the composite insulators and the heads of transmission towers is calculated by a model coupling the indirect boundary-element method to the moment method. The heterogeneous media, such as the composite insulators and the filament metal structures such as the transmission towers and the transmission lines, are considered altogether. The method can take into account not only the permittivity but also the resistivity of the media by using the complex resistivity in the frequency domain. The electric-field distribution around a three-phase 330-kV transmission tower with composite insulators was analyzed. The electric fields on the surfaces of the grading rings and the phase subconductors and at the ends of the composite insulators are analyzed. Both the method and the results are useful for the design of high-voltage transmission lines.

The effect of ionic liquids on product yield and catalyst stability has been investigated through Suzuki cross-coupling of phenylboronic acid and 4-bromoacetophenone in organic solvents, ionic liquids and mixtures of organic solvents and ionic liquids.

Solvent transport in organic solvent nanofiltration membranes has been studied in a lab-scale cross-flow nanofiltration rig over extended periods using the common solvents methanol, toluene, ethyl acetate and their mixtures. The organic solvent nanofiltration membranes STARMEM™ 122 1 (W.R. Grace and Co.) and MPF50 (Koch Membrane Systems) were investigated. It was found that it took a few days to obtain stable solvent flux using STARMEM™ 122, and that the solvent flux in this membrane showed good repeatability between different sample discs. MPF50 did not provide reproducible results, therefore, no modelling/data analysis was performed for this membrane. Our experimental data shows that both solution-diffusion and pore-flow models can be used to predict permeation of solvent mixtures, using only the permeabilities of the pure solvents to obtain input parameters to each model. The solution-diffusion model gave more accurate predictions. Our conclusion is that for the solvents studied, it is possible for reasonable predictions of solvent mixture flux to be made over the whole concentration range, based on the data for pure solvents.

An elliptical artificial boundary is introduced in the hybrid finite element method-analytical approach (FEM-ANA) for open boundary 2-D electromagnetic problems. It includes, as a special case, the circular artificial boundary (CAB) of Chari. The new artificial boundary (AB) is more flexible close to the configuration of the interested region than CAB, and makes the computation region of FEM reduced; meanwhile, it enlarges analytical solution region. The cost of the analysis of the exterior region for the two ABs is almost the same. The proposed approach is applied in analysis of electrostatic field and eddy current field problems.

This paper proposes a semi-analytic finite element method to treat the open boundary axisymmetric electrostatic field problems. The method is applied to computing the potential distribution of the high voltage porcelain metal oxide arrester (MOA). The numerical example shows a good agreement between the calculated and measured results.

Based on the idea of region division a technique known as the hybrid finite-element analytical approach is developed for treating axisymmetric open-boundary eddy-current field problems. The general principle of the technique first introduces a spherical fictitious surface boundary called a coupling boundary to enclose the complex-shaped devices in the presence of an inhomogeneous, anisotropic or even nonlinear medium. In the interior of the spherical fictitious surface boundary the field is formulated by the finite-element method (FEM). Meanwhile, in the exterior region the field is presented by an eigenfunction expression (in Legendre functions). Taking the exterior region as a macroelement, it requires consideration of only the potential continuity at the fictitious boundary nodes with interior finite elements, so the FEM is extended to solve open-boundary problems. The results were compared with both the analytical solution and experimental cases, showing good agreement. The new hybrid scheme combining an analytical solution with the finite-element method offers several advantages: symmetrical matrices; much fewer elements and nodes for the same level at accuracy; and an easy means for calculating the external region field.

This paper describes ideas together with preliminary experimental results for applying solvent nanofiltration to liquid phase organic synthesis reactions. Membranes for organic solvent nanofiltration have only recently (during the 1990s) become available and, to date, have been applied primarily to food processing (vegetable oil processing, in particular) and refinery processes. Applications to organic synthesis, even at a laboratory feasibility level, are few. However, these membranes have great potential to improve the environmental performance of many liquid phase synthesis reactions by reducing the need for complex solvent handling operations. Examples that are shown to be feasible are solvent exchanges, where it is desired to swap a high molecular weight molecule from one solvent to another between separate stages in a complex synthesis, and recycle and reuse of homogeneous catalysts. In solvent exchanges, nanofiltration is shown to provide a fast and effective means of swapping from a high boiling point solvent to a solvent with a lower boiling point-this is a difficult operation by means of distillation. Solvent nanofiltration is shown to be able to separate two distinct types of homogeneous catalysts, phase transfer catalysts and organometallic catalysts, from their respective reaction products. In both cases the application of organic solvent nanofiltration allows several reuses of the same catalyst. Catalyst stability is shown to be an essential requirement for this technique to be effective. Finally, we present a discussion of scale-up aspects including membrane flux and process economics.

Overall mass transfer coefficients (OMTCs) during membrane solvent extraction (MSE) for a microfiltration membrane Accurel, an organic solvent nanofiltration (OSN) membrane MPF 50, and silicone rubber were investigated with a hydrophilic solute (phenol) and a hydrophobic solute (toluene) in a membrane solvent extractor. Decanol was used to extract phenol or toluene from water. In MSE of phenol from water, MPF 50 has an OMTC intermediate between Accurel and silicone rubber, and has a much higher breakthrough pressure than Accurel. For MPF 50, it was observed that the solute–membrane interaction makes a major contribution to the mass transport of hydrophobic compounds, such as toluene, through the membrane. This suggests that solution-diffusion type models may be more appropriate than pore-flow models for describing transport of solvents through these kinds of membranes.

A series of elastomers were investigated, by measuring their toluene permeability and acid resistance, for their potential for use in the extraction of organics from hydrochloric acid and other membrane processes utilising acidic aqueous phases. In this study, toluene was used as a solute in aqueous solution to measure permeabilities of the elastomers, and their acid resistance was assessed after immersion in 37 wt.% hydrochloric acid by tensile-strain tests. Silicone rubber has the highest permeability among the elastomers investigated in this study, but it has poor resistance to concentrated HCl. Polyoctenamer is the best membrane material in terms of permeability and acid resistance. Other olefin based materials such as poly(ethylene-co-propylene) and poly(ethylene-co-propylene-co-diene) (EPDM) are also good candidates. The permeability generally decreases with an increase in Tg for the elastomers investigated. However, for the EPDM materials with Tg values grouped around −60 °C, the relationship between Tg and permeabilities is not clear. A model derived from Flory–Huggins Theory and the Hildebrand and Scatchard equation was used to predict the partition coefficients of toluene between the elastomers and aqueous solution, and the predictive power found to depend critically on the value employed for the water solubility parameter. The diffusion coefficients of toluene in the elastomers can be explained by considering the polymer structure.

This paper describes a new process for recovery of aromatic acids and bases, the membrane aromatic recovery system (MARS). The process comprises a stripping vessel, where phenols are extracted through nonporous membranes and concentrated into a NaOH solution as phenolate, and a two-phase separator in which the solution collected from the stripping vessel is separated into a phenolic phase and an aqueous phase by adjusting pH to acidic conditions with the addition of HCl. Silicone rubber tubing was used as a membrane in this study. The temperature in the stripping vessel and NaOH concentration in the solution fed into the stripping vessel are two important operating parameters. In this study the temperature was 50°C and NaOH concentration 12.5 wt.%. At steady-state, the total phenol concentration in the stripping solution can be orders of magnitude higher than in the wastewater, ensuring a high phenol recovery efficiency. The work found phenol recovery efficiencies of over 94%, with a recovered organic-rich phase comprising 86.5 wt.% phenol, and the balance water. The overall mass transfer coefficients (OMTCs) for other phenols were investigated to demonstrate the wide potential applications of MARS technology. Insights into OMTCs and permeabilities of phenols include the effect of Reynolds number in the tube side on OMTC, and the effect of temperature on the permeabilities of phenolic compounds in the membrane. The membrane resistance dominates the OMTCs of phenols in this study. The van’t Hoff–Arrhenius relationship for the temperature dependence of the permeability of the penetrant through the polymer gave excellent agreement with our experimental data.

This paper presents a pioneering study of liquid dispersion in gas-liquid-solid circulating fluidized beds. The effects of the operating parameters, such as the gas velocity, liquid velocity and circulation flux of solids, on the liquid axial and radial dispersion coefficients were investigated. The experimental results indicated that the axial and radial liquid dispersion coefficients increased monotonically with increasing gas velocity; the axial liquid dispersion coefficients were insensitive to changes in the liquid velocity, but the radial liquid dispersion coefficients decreased with increasing liquid velocity; both the axial and radial liquid dispersion coefficients increased with increasing circulation flux of solids. Compared with traditional expanded beds, gas-liquid-solid circulating fluidized beds approach the ideal plug-flow reactor more closely.

An axial dispersion reactor model for gas–liquid reaction systems is proposed in this paper based on the penetration theory. The mass transfer mechanism accompanied by a chemical irreversible first-order reaction is mathematically treated in a new way in order to use its results to develop the model conveniently. Analytical solutions can be obtained for the equation system involving linear differential equations by using of the eigenvalues of the equation system. In addition, an iteration procedure is given to solve the nonlinear differential equation system numerically. The influences of the important model parameters on the concentration profile, the mass transfer and the reactant conversion are also studied.

In drinking water treatment flow fluctuations or surges can occur at the filtration stage. Pilot plant tests were carried out to investigate the impact of flow surges on filter performance in this study. Moreover a filtration model was applied to analyse the impact of flow surges on filter performance and predict the experimental data obtained from pilot plant tests. Experimental results showed that flow surges caused an increase in effluent particle concentration and head loss. Theoretical analysis in this study showed that the impact of a flow surge became more significant as the filtration run approaches the particle breakthrough stage. The model was also used to fit the data from one water treatment plant. The comparison demonstrated a good agreement.

This paper presents a hybrid finite element-analytical approach (FEM-ANA) for open boundary axisymmetrical eddy current problems based on vector potential A with a new prolate spherical surface fictitious boundary (PSSFB), which is the development of the previous spherical surface fictitious boundary (SSFB). The PSSFB can circumscribe the shape of the interested region, especially for long, slender shape, more closely than the SSFB, and therefore the domain computed by finite element method is reduced and, meanwhile, the region calculated by the analytical solution is enlarged, which will result in more efficiency and accuracy of the hybrid approach with PSSFB than those already reported with SSFB. A numerical example is given to demonstrate the efficiency and accuracy

In this paper, a hybrid finite element-analytical approach for 3D potential calculation for a station class ZnO surge arresters for 1100 kV substation is presented. In this hybrid approach a circular cylinder surface fictitious coupling boundary is employed to divide the infinite region into two an interior region and an exterior region. The field in the interior region involving a ZnO surge arrester of which the medium and configuration are complicated is discretized using finite element method, and meanwhile the field in the exterior region involving a homogeneous medium the eigenfunction expansion is represented. Many factors influencing on the visitors potential distribution are discussed. At lasts an appropriate grading ring configuration is suggested

The influences of electromagnetic transient on a 500 kV DC resistive divider are discussed based on the equivalent circuit considering stray parameters in this paper A finite element method is applied to evaluate the stray parameters of the DC resistive divider and PSpice software is used to simulate the responses of the equivalent circuit. The simulation results are analyzed and conclusions of influences on measurement results of the DC resistive divider are achieved.

It is essential for many EMC problems to evaluate the transient shielding effectiveness of thin metallic shells. A fast time domain approach is presented to calculate the transient shielding effectiveness of the thin metallic shells excited by an arbitrary waveform electromagnetic pulse. The frequency domain transfer function of the thin metallic shell is fitted into the rational function by the vector fitting method, and the pulse response can be expressed by a sum of decay exponentials in the time domain by the inverse Laplace transformation. The transient shielding effectiveness excited by an arbitrary waveform can be obtained easily based on the recursive convolution formulation. The advantage of the proposed method lies in two aspects. It is a time domain algorithm without needing the time-consuming FFT approach, and the scheme of recursive convolution can improve the calculation efficiency dramatically. The proposed approach is validated by some numerical examples.