地层压力下降对指数式产能方程的影响分析

随着地层压力的下降，与指数式产能方程流动系数密切相关的参数，如天然气偏差系数、天然气粘度、气层渗透率、有效厚度等都是变化的。气层渗透率、有效厚度的变化甚微，相比之下可以忽略不计；而天然气偏差系数和粘度的变化却不容忽视，两者之乘积不断变小，由此引起指数式产能方程流动系数不断增大。通过分析，给出了指数式产能方程流动系数随天然气偏差系数和粘度对应变化的关系式。当已知气井某一时刻的指数式产能方程后，便可确定任意地层压力下的气井产能，从而更准确地指导气井开采，避免重复试井工作。     

On-line automatic optical inspection system for coarse particle size distribution

A new online automatic optical inspection system (OAOIS) using digital image processing has been developed to measure the coarse particle size distribution. The OAOIS is composed of particle separation module, image acquisition module, image processing and analysis module and PC/PLC-based electric control module. Experiments were performed with non-uniform particles (1-100 mm). The particle size distribution, number of the particles, and accumulated weight percentages of particles are obtained by using the developed system. The experimental results show that the repeated precision of accumulated weight percentages is around ± 1%. To improve the reliability and accuracy of the OAOIS measuring results, the linear regression equation is applied to mapping the result of OAOIS to that of traditional net sieving system (TNSS). It has been shown that the developed system has a high accuracy and precision for coarse particle sizing distribution.     

Formation of acid‐precipitated soy protein–dextran conjugates by Maillard reaction in liquid systems

The conjugation reaction between soybean acid‐precipitated protein (SAPP) and dextran in liquid systems via the initial stage of the Maillard reaction was studied. Functional SAPP–dextran conjugates were prepared in 80% ethanol‐reacting system at 50 °C for 6 h, along with 95% ethanol‐reacting system at 60 °C for 24 h. The covalent attachment of dextran to SAPP was confirmed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis and gel filtration chromatography.Compared to the classical dry‐heating, the reaction time of glycosylation in the two ethanol systems was largely shortened. Emulsifying activity of SAPP–dextran conjugates obtained by dry‐heating incubation and in ethanol was similar at pH 7.0 and10.0, significantly higher than that of SAPP–dextran mixture or SAPP alone. In addition, SAPP–dextran conjugates obtained in 80% ethanol‐reacting system for 6 h were completely soluble after heating at 90 °C for 20 min. The impact of various processing conditions on the formation of SAPP–dextran conjugates was investigated. This study provides important guidance to create protein–polysaccharide conjugates at mild temperatures in liquid systems.     

Forced convective flow and heat transfer characteristics of aqueous drag-reducing fluid with carbon nanotubes added

A new kind of aqueous drag-reducing fluid with carbon nanotubes (CNTs) was developed. The new working fluid was an aqueous CTAC (cetyltrimethyl ammonium chloride) solution with CNTs added and has both special effects of drag-reducing and heat transfer enhancement. The thermophysical and rheological properties of the new working fluid were measured. An experiment was carried out to investigate the forced convective flow and heat transfer characteristics of conventional drag-reducing fluid (aqueous CTAC solution) and the new drag-reducing nanofluid in a test tube having an inner diameter of 25.6 mm. Results indicated that there were no obvious differences of the drag-reducing characteristics between conventional drag-reducing fluid and new drag-reducing nanofluid. However, there were obvious differences of the heat transfer characteristics between both fluids. The heat transfer characteristics of new drag-reducing nanofluid have strong dependences on the liquid temperature, the nanoparticle concentration and the CTAC concentration. The heat transfer enhancement technology of nanofluid could be used to solve the problem of heat transfer deterioration for conventional drag-reducing fluids.     

同步顶升法在化工装置改造中的应用

大庆石化公司炼油厂二重催MIP改造空冷器平台整体提升施工难度较大,经过分析、计算、方案对比,提出采用千斤顶同步顶升方法替代传统的吊装工艺,顺利的完成了260 t重的空冷器平台整体提升任务,不仅节约施工成本,同时还探索出一条化工装置有限空间施工的新途径。     

现代大客车技术分析

通过对国内外大客车三大总成的最新技术进行分析，探讨我国大客技术的发展方向。     

新型永磁式开关磁阻电动机电磁场的二维有限元分析

采用二维有了元模型对新型永磁式开关磁阻电动机的电磁场了分析。     

Numerical electromagnetic analysis of impulse voltage measuringsystems

The unit step response (USR) of lightning impulse voltage measuring systems is numerically calculated with the help of the Numerical Electromagnetic Code (NEC-2), which calculates the three-dimensional electromagnetic field around conducting wires. The accuracy of this analysis is proved satisfactory through comparison of the results of measurement with calculation. The advantage of this method is that the influence of the geometry of the circuit can automatically be calculated without evaluating stray capacitance in the system. Therefore, this method of analysis can be applied to the development of an impulse voltage divider, or in analyzing the influence of elements of a USR measuring circuit. The influence of the shield ring attached to a resistance divider, and of the vertical metal sheet in the IEC-recommended USR measuring circuit on the USR waveform is analyzed as an example