电镀废水治理方案浅谈

物化-生物-膜法组合是电镀废水治理的主流工艺,物化法能够有效降低电镀废水中的重金属离子,生物法能有效去除有机物,膜法进一步截留全部污染物。结合三者的优点,能够有效降低电镀废水的处理成本,提高电镀废水的再生率。前处理废水和反渗透浓水混合厌氧处理即可去除有机物,也能降低废水中硫酸根,是电镀废水治理的发展方向。     

Moving bed syngas conditioning: Modelling

This paper presents a modelling approach for simulating tars and particulate (dust) removal in a moving bed heat exchange filter (MBHEF) in order to satisfy gas requirements of end-use syngas applications: engines and turbines. The two-dimension, adiabatic, steady-state proposed model accounts for two-phase (gas and solid) and neglects conduction and mass diffusion. Tars condensation is modelled through representative tar class lumps: phenol (class 2), naphthalene (class 4), pyrene (class 5). The model also considers tar concentration influence on the tar dew point. The filtration model is taken from literature. A sensitivity analysis is performed varying the particle size and the superficial gas velocity. Maps of temperature and tars abatement efficiency are presented. The simulation results indicate the feasibility of the use a MBHEF as tars removal equipment benefiting its advantages against others gas-cleaning methods with acceptable pollutant removal efficiencies, ranging 88–94% for ranges studied. Results also point out low gas velocities (0.5-1 m/s) and high particle size (400–700 μm) for reducing operational costs in MBHEFs with compact size.     

厌氧生化处理技术深度除铜的试验研究及工程应用

通过对重金属废水的前期试验研究结果[1],采用厌氧生化技术针对重金属废水痕量铜的试验研究,试验结果显示当原水痕量铜离子浓度低于2.5 mg/L时,经过厌氧生化处理后铜离子浓度低于0.3 mg/L。推广到实际工程应用,结果证明,该技术应用非常成功,从2013年起至今,工程运行结果稳定,运行费用低,当原水铜浓度低于2.0 mg/L时,出水铜离子浓度可以达到《电镀污染物排放标准》(GB 21900-2008)水污染物排放标准表3标准,即低于0.3 mg/L,该技术具有处理效率高,难受冲击负荷高,应用范围广,处理成本低等优点,具有非常大的实际推广意义。     

Surfactant-assisted synthesis and catalytic activity for SOx abatement of high-surface-area CuMgAlCe mixed oxides

CuMgAlCe mixed oxides were prepared by a modified coprecipitation–calcination method using CTAB as surfactant template. All the precursors showed hydrotalcite-like layered structure and mixed oxides with mainly periclase phase were obtained after calcination. Catalytic activity for SO₂ removal of mixed oxides was examined through adsorption–reduction cycles under the conditions similar to those of FCC units. The results showed that incorporation of both Ce and Cu could improve SO_x oxidative chemisorption. CTAB/metal molar ratio during synthesis had a significant influence on the structural properties of mixed oxides. Sample CuMgAlCe-0.1 prepared by CTAB/metal molar ratio of 0.1 had the highest specific area 142.2 m²/g and also presented the best SO₂ adsorption rate and capacity. This behavior is mainly due to its exposed more adsorption sites provided by high specific surface area, facilitating SO₂ diffusion and contact with active components. It still possessed excellent cyclic stability that is beneficial for industrial application.     

Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

Solar powered high voltage energization for vehicular exhaust cleaning: A step towards possible retrofitting in vehicles

This paper proposes a novel way of generating high voltage for electric discharge plasma in controlling NO_x emission in diesel engine exhaust. A solar powered high frequency electric discharge topology has been suggested that will improve the size and specific energy density required when compared to the traditional repetitive pulse or 50 Hz AC energization. This methodology has been designed, fabricated and experimentally verified by conducting studies on real diesel engine exhaust.     

Dynamic stiffness removal for direct numerical simulations

A systematic approach was developed to derive non-stiff reduced mechanisms for direct numerical simulations (DNS) with explicit integration solvers. The stiffness reduction was achieved through on-the-fly elimination of short time-scales induced by two features of fast chemical reactivity, namely quasi-steady-state (QSS) species and partial-equilibrium (PE) reactions. The sparse algebraic equations resulting from QSS and PE approximations were utilized such that the efficiency of the dynamic stiffness reduction is high compared with general methods of time-scale reduction based on Jacobian decomposition. Using the dimension reduction strategies developed in our previous work, a reduced mechanism with 52 species was first derived from a detailed mechanism with 561 species. The reduced mechanism was validated for ignition and extinction applications over the parameter range of equivalence ratio between 0.5 and 1.5, pressure between 10 and 50 atm, and initial temperature between 700 and 1600 K for ignition, and worst-case errors of approximately 30% were observed. The reduced mechanism with dynamic stiffness removal was then applied in homogeneous and 1-D ignition applications, as well as a 2-D direct numerical simulation of ignition with temperature inhomogeneities at constant volume with integration time-steps of 5-10 ns. The integration was numerically stable and good accuracy was achieved.     

Study of different types of monomer emulsion feedings to semibatch emulsion polymerization reactors

Semibatch emulsion polymerization processes with a monomer emulsion feed are of great importance in both academia and industry. Monomer emulsion feeds can be applied to semibatch reactors using either a stream of an emulsified monomer or two streams of a neat monomer feed and an aqueous solution of an emulsifier. The effect of the feeding policy on the rate of polymerization and on the secondary particle formation was studied for a seeded semibatch emulsion polymerization of styrene. When a single-stream monomer emulsion feed is applied to a semibatch process, the monomer-swollen micelles formed in the feed might become the locus of initiation upon entering the reaction vessel. Under the conditions of this study, the application of monomer emulsion feed in either one stream or two streams did not result in secondary particle formation. The incoming monomer-swollen micelles were disintegrated to supply emulsifier molecules for the stability of growing particles, before they can capture radicals and become polymer particles. The rate of polymerization was found to be independent of the way that the monomer emulsion feed is added. In the absence of nitrogen, the rate of polymerization decreased more appreciably for the monomer emulsion feed, due to the oxygen dissolved in the emulsified monomer. The number of particles, however, was not affected by the purging policy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2472–2477, 2001     

渣罐耳轴的液氮冷装工艺

在装配大过盈量零件时,热装工艺有时无法完成,需采用液氮冷装工艺才能较好的完成设计要求。文章对渣罐耳轴的具体装配过程进行了详细的介绍,并用一些具体的数据、图像进行了工艺分析。