Estimation of saturated air water content at elevated pressures using simple predictive tool

In a compressed air system, condensed water vapor can have corrosive effects on metals and wash out protective lubricants from tools, equipments and pneumatic devices. To protect against such undesirable effects in a compressed air system, it is necessary to be able to predict the water content of air in order to design and apply the appropriate type of drying to be used in the system. In this work, a simple predictive tool, which is easier than currently available models and involves a fewer number of parameters, requiring less complicated and shorter computations, is presented here for the prediction of water content of air as a function of temperature and relative humidity as well as for compressed saturated air as a function of pressure and temperature using an Arrhenius-type asymptotic exponential function. The proposed method predicts the amount of air water content for temperatures up to 45 °C, pressures up to 1400 kPa and relative humidities up to 100%. Estimations are found to be in excellent agreement with the reliable data in the literature with average absolute deviation being less than 1.4 and 2.2% for atmospheric air and saturated compressed air, respectively. The tool developed in this study can be of immense practical value for engineers and scientists to have a quick check on the water content of atmospheric air and saturated compressed air at various conditions without opting for any experimental measurements. In particular, engineers and scientists would find the approach to be user-friendly with transparent calculations involving no complex expressions.     

涡凹气浮技术在污泥浓缩中的应用

介绍了PTA废水处理系统的污泥处理工艺流程及涡凹气浮技术的工作原理,阐述了该技术在污泥浓缩中的应用情况,验证分析了药剂投加量、固体负荷、水力负荷等对污泥浓缩效果的影响,对比了涡凹气浮技术应用前后的不同效果,提出了运行中出现泥层过厚问题的解决方法。     

Flotation efficiency of activated sludge flocs using population balance model in dissolved air flotation

The activated sludge process is one of the most frequently used processes for biological wastewater treatment. Conventional gravity sedimentation (CGS), which is widely used as a secondary clarifier in activated sludge processes, has a routine problem due to floating tendency, called bulking, caused by filamentous microorganisms. Dissolved air flotation (DAF) has been applied as potential alternative to CGS as a secondary clarifier. A series of experiments were performed to measure physico-chemical characteristics and removal efficiency of activated sludge flocs. The removal efficiency of flocs corresponding in lag and exponential growth phases was lower, while that of flocs both in stationary and endogenous phases considerably increased. The rise velocity of floc/bubble agglomerates was calculated by using a population balance (PB) model explaining the distribution of floc/bubble agglomerates. The experimental results of flotation efficiency showed a similar tendency with the results predicted by PB model for the rise velocity and distribution of floc/bubble agglomerates. It was found from our study that the DAF process was very effective as a secondary clarifier in the activated sludge process.     

气浮接触区气泡聚并行为的数值模拟

在气浮接触区内,聚并会导致气泡直径增大,对分离效果产生影响。采用相群平衡模型对接触区气泡聚并行为进行数值模拟,研究了气泡聚并发生的原因及来液流量、回流流量对气泡聚并的影响。首先分别应用Schiller-Naumann、Grace和Tomiyama3种曳力系数模型进行模拟,所得气泡直径均与实验值吻合,无明显差异,选定Schiller-Naumann曳力系数模型对气浮中两相流动进行模拟。通过对模拟结果进行分析,表明回流入口周围上下行流过渡区域存在较大速度梯度,是导致气泡聚并的关键因素。最后研究了来液流量和回流流量对接触区气泡尺寸的影响,接触区上部气泡直径随回流流量增大而明显增大,原因在于增大回流流量使得过渡区域速度梯度升高,气泡聚并频率提高;而来液流量对气泡尺寸基本无影响。     

Enhancing the recovery and concentration of polyphenols from camu-camu (Myrciaria dubia H.B.K. McVaugh) by aqueous two-phase flotation and scale-up process

In this study, polyphenols obtained from camu-camu pulp residue were recovered and concentrated from aqueous two-phase flotation (ATPF) by evaluating different operating conditions, such as solvent type, pH, ammonium sulfate concentration, flotation time, air flow, and volumetric ratio. Under optimal conditions, the polyethylene glycol 400/ammonium sulfate ATPF system showed an efficiency of 81.02% and a concentration coefficient two times higher than traditional aqueous two-phase extraction. Experiments were also carried out on a semi-pilot scale, using an apparatus with a 2.5-L working volume. The results showed that the semi-pilot system was comparable to the smaller scale system.     

Elimination of chlorobenzene vapors from air in a compost‐based biofilter

In this work, the removal of monochlorobenzene (CB) vapors from air was studied, for the first time, in a non‐inoculated, laboratory‐scale, aerobic biofilter. The influence of three parameters on the bioprocess has been evaluated: the rate of nitrogen supplied to the bed, the inlet concentration of CB, and the flow rate. The CB inlet concentration was varied between 0.3 and 3.2 g m^?3, at a constant flow rate of 1.0 m³ h^?1. Removal rates of greater than 90% were achieved for CB inlet concentrations of up to 1.2 g m^?3. Then the flow rate was varied from 0.5 to 3.0 m³ h^?1 with a constant inlet concentration (1.2 g m^?3). Maximum elimination capacities (70 g m^?3 h^?1) were reached for contact times of greater than 60 s. The study of varying flow rates also permitted evaluation of a first order macrokinetic constant (1.1 × 10^?2 s^?1) for the CB biodegradation. Finally, the optimum nitrogen input value was found to lie between 0.3 and 0.4 g N h^?1 and gave rise to elimination capacities as high as 70 g m^?3 h^?1 for an inlet load of near 80 g m^?3 h^?1. Copyright © 2003 Society of Chemical Industry     

Estimation of spatial alumina concentration in an aluminum reduction cell using a multilevel state observer

In the Hall‐Héroult process, spatial variations in alumina concentration are very difficult to measure and impossible to estimate from the conventionally monitored line amperage and cell voltage. This article presents an approach to estimate in real time the alumina concentration distribution in an aluminum reduction cell based on individual anode current measurements. One of the key difficulties is that the localized mass transfer rates are unknown. To overcome this issue, a multilevel state observer is developed based on the robust extended Kalman filter. The approach utilizes a dynamic model of a reduction cell that is discretized subsequently level by level, where the estimated variables at each level are used to estimate more detailed alumina concentration spatial distribution at the next level. The proposed approach is validated in an experimental study using an industrial cell. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2806–2818, 2017     

高效液相色谱法测定空气中苯并(a)芘

用无胶玻璃纤维滤筒或玻璃纤维滤膜采样,超声波作用下以环己烷提取苯并(a)芘,提取液经KD浓缩器浓缩,配有荧光检测器的高效液相色谱仪进行测定。该法灵敏度高,再现性好,简便快速,适合于环境空气中苯并(a)芘的测定,同时也适用于污染源和水中苯并(a)芘的测定。     

Design composite oxide supported Pt catalyst for catalytic wet air oxidation of ammonia with a high concentration in chloride system

Massive discharge of ammonia nitrogen wastewater not only causes eutrophication of the water body but also has a toxic effect on humans and living things. How to deal with ammonia nitrogen wastewater is a crucial topic for researchers. Here, a novel catalyst of Pt@Ti–Si where platinum was supported on a composite oxide of titanium oxide (TiO₂) and silicon oxide (SiO₂) via a one-pot method was successfully synthesized for catalytic wet air oxidation (CWAO) of ammonia with a high concentration (more than 2000 ppm). Due to the improved specific surface area of SiO₂ and the excellent acid-base resistance of TiO₂, the prepared composite oxide-supported platinum catalyst has excellent catalytic performance and good stability for CWAO with a high concentration of ammonia. At 200 °C and the O₂ pressure of 2 MPa for 2 h, the 1%Pt@Ti10–Si1 catalyst has a 96.32% conversion of 2470 ppm ammonia and 97.15% selectivity to N₂ and has good catalytic performance even after five cycles. Under the same reaction conditions, when the chloride concentration in the system is 3000–10000 ppm, the CWAO reaction can be inhibited at an early stage and promote conversion and selectivity at a later stage. The results show that the catalyst has good tolerance to chloride ions, and the treated ammonia nitrogen wastewater can be used for subsequent biochemical processes. Therefore, the developed novel catalyst in this study is effective for the CWAO of highly concentrated ammonia and has potential industrial application value.     

大处理量紧凑型气浮装置的数值模拟

目前鲜有关于大处理量气浮装置结构设计研究方面的报道,气浮装置国产化研究进程缓慢。为了解决这 一问题,本文以自主研发的处理量为120m³/h 紧凑型气浮装置为计算模型,采用Eulerian 模型和RNG k-ε 湍流模 型,运用Fluent 对其三维流场进行了数值模拟研究。分别研究了内筒高度、半径间隙及入口管径等结构参数和 含油量、处理量等操作参数的影响,以便考察和优化气浮装置的分离性能。结构参数影响的数值模拟结果表明: 随着半径间隙的减小,除油率先增大后减小;随着入口管径的减小,除油率先减小后增大;改变内筒高度对除 油率的影响较小。操作参数影响的数值模拟结果表明,装置的操作弹性相对较大,对水质水量一定程度的波动 具有良好的适应性。     

Investigation of machinability in milling of Inconel 718 with solid Sialon ceramic tool using supercritical carbon dioxide (scCO2)-based cooling conditions

Milling of hard-to-machining materials is still a challenge since the high cutting temperature caused by the cooling lubrication problems and the property of materials. This paper proposes the use of supercritical carbon dioxide (scCO₂), supercritical carbon dioxide based minimum quantity lubrication cutting fluid (scCO₂-MQL), and supercritical carbon dioxide based minimum quantity lubrication with oil droplets cutting fluid (scCO₂-OoW) as the eco-friendly cooling-lubrication methods for milling of Inconel 718 superalloy. The cutting forces, cutting temperatures, surface roughness, surface topographies, subsurface characteristics and tool wear were performed to quantify the effect of various cooling methods. The results indicated that the application of scCO₂-based cooling conditions was an effective cooling and lubrication technology for the ceramic tool since it could reduce the cutting force and temperature and improve the surface finish with lower peaks and valleys dispersion compared with other cooling conditions. Compared with the scCO₂-MQL, only scCO₂ and dry milling conditions, the topographies of machined surface under the scCO₂-OoW condition have been significantly improved. Furthermore, the scCO₂-OoW cooling technique has facilitated the removal of debris adhering to the ceramic tool and improved lubrication of the cutting zone.     

Graft copolymerization of acrylonitrile onto poly(vinyl alcohol) in presence of air using ceric ammonium nitrate‐natural gums

In an attempt to overcome the problem of polymerization of vinyl monomers in presence of oxygen, polymerization was done by using some plant gums. The effect of some plant gums were studied on the graft copolymerization of acrylonitrile (AN) on to poly(vinyl alcohol) using ceric ammonium nitrate (CAN) as initiator in presence of air. Percent of grafting was determined as a function of nitric acid, concentration of monomer, time, and temperature. The rate of polymerization and maximum grafting (151%) were high compared with those in absence of the gum both in air of even in an inert atmosphere. Thus, it was definitely observed that the graft copolymerization is affected by the gum. From the differential scanning calorimetric (DSC) studies the glass‐transition temperature Tg of polyacrylonitrile (PAN) is found to be 56°C. Thermal stabilities were checked by thermogravimetric analysis (TGA) and this indicated that the grafted copolymers were resistant to moisture absorption. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1586–1590, 2000     

Removal of Pb(II) from simulated wastewaters using a stainless-steel wool cathode in a flow-through cell

The investigation of an electrolytic process to remove Pb(II) from simulated wastewaters using a stainless-steel wool (SSW) cathode in a flow-through cell under potentiostatic condition is reported. Voltammetry under hydrodynamic conditions was used to estimate the diffusion coefficient, which was found to be 1.4× 10⁻⁵ cm² s⁻¹ in the supporting electrolyte (0.10 mol l⁻¹ NaNO₃ and 0.10 mol l⁻¹ H₃BO₃, pH 4.8). The performance of the flow-through cell was evaluated for three potentials: −0.70, −0.80 and −0.90 V vs. saturated calomel electrode (SCE). At −0.70 V, the reaction was found not to be completely controlled by mass transfer, while at −0.80 V and −0.90 V the Pb(II) concentration decayed exponentially. At −0.90 V, using a flow rate of 250 l h⁻¹, after a 90-min electrolysis, the Pb(II) concentration decayed from 50 ppm to only 1 ppm, corresponding to a 98% removal.     

Ultrasonic-assisted wetting and soldering of AlN ceramic by using a nonactive solder (Sn9Zn) in air

AlN ceramic was successfully wetted and then joined with nonactive Sn9Zn eutectic solder assisted by ultrasonication in air. The effect of ultrasonic time on the formation of joint was studied. Results indicated that the defect-free joint can be obtained at an ultrasonic time of 5 s. Two regions, namely, AlN/Sn (s,_s) and AlN/Zn (s,_s), were found in the bonding interface. Zn and O accumulated in the AlN/Sn (s,_s) interface. An amorphous and nanocrystalline layer of ZnO formed in the hard-wet AlN surface. And Zn (s,_s) directly bonded with AlN. The low temperature and fast bonding of the AlN was attributed to the high pressure and temperature caused by cavitation effect. The shear strength of the joint increased from 10.6 MPa to 30.7 MPa when the ultrasonic treatment time increased from 5 s to 150 s. With the prolongation of ultrasonic time, more AlN ceramic particles entered the solder and acted as the reinforcing phase.