SCADA系统在长输管线中的应用

介绍珠三角成品油管线采用基于工业微机和可编程控制器的计算机数据采集与监控(SCADA)系统,并对控制系统的系统结构包括控制层和操作站层、硬件软件配置、安装组态和系统特点作了论述,同时对系统应用开发过程的体会作了说明。SCADA系统通过远程终端装置(RTU)、PLC,实现整个工业网络的监控,从而保证系统的安全运作及优化控制。     

CONCENTRATION POLARIZATION OCCURRING INSIDE THE MEMBRANE DURING STEADY STATE PERVAPORATION

Experimental profiles of a single penetrant (water) across the membrane have been established at different downstream pressures during steady state pervaporation. The profiles ofacetic acid-water binary penetrant system across the membrane were also measured at different downstream pressures, temperatures and compositions during steady state pervaporation. A stack of identical pre-characterized symmetric aromatic polyamide membranes was used for the profile study. The theoretical prediction of concentration polarization from mathematical equations has been confirmed by the experimental profile data for a binary penetrant system.     

Solute transport in poly(2-hydroxyethyl methacrylate) hydrogel membranes

The swelling, permeation, and release characteristics for benzoic acid, caffeine, propranolol hydrochloride, and diclofenac sodium in crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels were examined. Increasing polymer crosslinking density resulted in decreases in the degree of swelling, drug loading, the diffusivity of solute in the hydrogels, and in the rate of drug release. Diclofenac sodium led to an abnormally large degree of swelling as the maximum value is given as 6.5, while the highest for the other three was 1.07. That the logarithmic drug diffusivity was proportional to the reciprocal of hydration indicates that the free volume theory accounts for the transport of solute in the gels. Increasing the concentration resulted in increases in the diffusivities, solubilities, and permeabilities of the solutes in the hydrogels. The drug release kinetics from most wet hydrogel samples can be well-fitted by a Fickian diffusion model. Near zero-order release is observed only for dry samples with caffeine of low loading.     

长输管道建设中焊接设备的应用现状与发展趋势

针对长输管道建设的施工现场不固定,施工环境复杂多变,施工固定条件不稳定,全位置焊接操作。焊接工艺种类多等特点进行了管道焊接施工用焊接设释的选型分析,认为用于长输管道建设的焊接设备应环境适应能力强,可靠性高,工艺适应性好,控制面板简单易懂,调节方便。列举了我国长输管道建设过程中得到成功应用的焊接电源和设备,并对未来长输管道建设中焊接设备的发展进行了展望。     

Gas and water vapour transport in a polyketone terpolymer

Gas and water vapour transport properties of a polyketone terpolymer (0.93/0.07/1 ethylene/propylene/carbon monoxide) have been investigated and related to the polymer structure. Permeability tests have been performed at several temperatures (from 25 to about 65°C) with five different gases (oxygen, nitrogen, methane, ethane and carbon dioxide), evaluating permeabilities, diffusivities and solubilities. Their dependence on temperature was interpreted on the basis of apparent activation energies of permeation and diffusion (E_P and E_D) and of heats of solution (ΔH_S). The investigated polymer was found to be rubbery at the test temperatures (glass transition temperature is about 17°C), but the detected permeabilities are comparable to those of the glassy polymers widely used for packaging applications. Data obtained in this investigation on samples exposed to moulding temperatures (240°C) for 3 min were compared to gas permeation data (presented in a previous paper) obtained for samples exposed at that temperature for 33 min in order to assess possible effects on gas transport properties. Water vapour transport was analysed by performing both sorption (35, 34, 55 and 65°C) and permeation (35°C) experiments at several activities. The analysis of sorption isotherms revealed the occurrence of water clustering, which was confirmed by a reduction of water diffusivity as a function of water concentration in the polymer.     

Continued development of a mass balance model of chemical fate in a sewage treatment plant

Chemicals that pass through a sewage treatment plant (STP) and into receiving waters lead to exposure of human and ecological receptors. Most countries require that such chemicals and especially those that are new to commerce be assessed for their treatability in STPs using a screening-level model. The STP model has been widely used for such assessments in Canada, the US and elsewhere. It is important for both industry and regulators that such a model be simple, accurate and applicable even with the limited data available for most chemicals. The STP model has been upgraded to include the capability to handle ionizing chemicals, and a variety of treatment plant configurations commonly used in Canada and elsewhere around the world. A scheme for obtaining appropriate biodegradation half-lives for the different treatment options from available aqueous biodegradation half-lives or standard biodegradability tests is suggested. Model simulations show good agreement with pilot-scale experimental data from literature for 20 organic chemicals with widely varying physico-chemical properties.     

A general mechanistic model for predicting the fate and transport of phthalates in indoor environments

A mechanistic model that considers particle dynamics and their effects on surface emissions and sorptions was developed to predict the fate and transport of phthalates in indoor environments. A controlled case study was conducted in a test house to evaluate the model. The model‐predicted evolving concentrations of benzyl butyl phthalate in indoor air and settled dust and on interior surfaces are in good agreement with measurements. Sensitivity analysis was performed to quantify the effects of parameter uncertainties on model predictions. The model was then applied to a typical residential environment to investigate the fate of di‐2‐ethylhexyl phthalate (DEHP) and the factors that affect its transport. The predicted steady‐state DEHP concentrations were 0.14 μg/m³ in indoor air and ranged from 80 to 46 000 μg/g in settled dust on various surfaces, which are generally consistent with the measurements of previous studies in homes in different countries. An increase in the mass concentration of indoor particles may significantly enhance DEHP emission and its concentrations in air and on surfaces, whereas increasing ventilation has only a limited effect in reducing DEHP in indoor air. The influence of cleaning activities on reducing DEHP concentration in indoor air and on interior surfaces was quantified, and the results showed that DEHP exposure can be reduced by frequent and effective cleaning activities and the removal of existing sources, though it may take a relatively long period of time for the levels to drop significantly. Finally, the model was adjusted to identify the relative contributions of gaseous sorption and particulate‐bound deposition to the overall uptake of semi‐volatile organic compounds (SVOCs) by indoor surfaces as functions of time and the octanol‐air partition coefficient (K_oa) of the chemical. Overall, the model clarifies the mechanisms that govern the emission of phthalates and the subsequent interactions among air, suspended particles, settled dust, and interior surfaces. This model can be easily extended to incorporate additional indoor source materials/products, sorption surfaces, particle sources, and room spaces. It can also be modified to predict the fate and transport of other SVOCs, such as phthalate‐alternative plasticizers, flame retardants, and biocides, and serves to improve our understanding of human exposure to SVOCs in indoor environments.     

Tribological behavior and wear mechanisms of TiN/TiCN/TiN multilayer coatings

This work employs the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN⇔⇔N, and sequenced TiN⇔CN⇔N multilayer coatings with variable individual TiN-layer and TiCN-layer thicknesses on tungsten carbide disks and inserts. Also investigated are the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk, line-contact wear mode and ball-on-disk, point-contact wear mode through SRV reciprocating wear tests. Actual milling tests identify wear performance. Experimental results indicate that the coating with a total thickness of 7 Μm and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. No-tably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.     

高速往复压缩机管网振动研究

对高速往复压缩机管网振动进行了测试和阶比谱频率分析,找出了振动原因,确定出实际可行的减振方法和处理措施,经过改造后的机组,原振动较大点幅值得到大幅度降低。经长期运行后,振动点幅值无增大现象,根本解决了该机组管网振动严重、故障频繁、不能平稳运行等问题。     

Analytical techniques in high temperature corrosion

This paper considers the application of analytical techniques (particularly AES, SIMS, RHEED, laser Raman, Mössbauer, TEM, EELS) to high-temperature oxidation studies. Specific systems reviewed include NiO on Ni, oxides on Fe, Cr and their alloys, and Al₂O₃ on Al and -NiAl. The often complementary information provided by the various techniques leads to a better understanding of oxide growth mechanisms on an atomic sale, interfacial segregation phenomena, and the role of reactive elements in modifying transport processes in oxides.