Molecular weight and concentration effects on gel/sol transitions in a segmented rigid-rod polyimide solution

Gel/sol and order/disorder transitions can be observed in a segmented rigid-rod polyimide solution at different concentrations and molecular weights. This polyimide was synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl in refluxing 3-cresol in a one-step process. Above about 140°C, the polymers are completely soluble in 3-cresol in a concentration range up to 12(w/w)%. During cooling, the hot solutions undergo a mechanical sol/gel transition to form thermally reversible gels. In the gel state, an ordered structure develops. Both the gel/sol and order/disorder transitions are dependent upon concentration, temperature, and molecular weight, but the two transitions exhibit different kinetics. Possible mechanisms of these transitions are discussed.     

聚合物驱后进一步提高采收率方法及其作用机理研究

聚合物驱后仍然有约50%原油残留于地下,聚合物驱后进一步提高采收率技术研究受到石油科技工作者的高度重视.该文利用物理模拟方法,对聚合物驱后进一步扩大波及体积和提高洗油效率技术方法的增油效果进行了评价.结果表明,聚合物驱后采用高浓度聚合物溶液、碱/表面活性剂/聚合物三元复合体系、碱/表面活性剂/交联聚合物三元复合体系和沸石/聚合物溶液驱都可以进一步提高原油采收率,采收率增幅在5.4%～7.6%之间.对于非均质油藏,扩大波及体积对采收率的贡献率大于提高洗油效率的贡献率.从技术和经济效果两方面考虑,沸石/聚合物溶液驱油体系更具应用价值.     

Oberflächenspannungsmesstechnik für den Prozesseinsatz

Using Surface Tension Measurement in Applications When cleaning surfaces it is crucial for the process stability that the optimum surfactant concentration is maintained. The concentration of free surfactants can be measured by determining the surface tension. SITA Messtechnik has developed an innovative sensor based on the bubble pressure method. This sensor makes it possible to continuously measure surface tension with a high reliability. With this application for monitoring cleaning baths the potential to save money arises in regard to the use of raw materials, waste disposal and the costs resulting from undiscovered production failures.     

Sensor Selective Gas Analyzer for Small Concentrations of Hydrogen Sulfide

A sensor (based on a MDS-capacitor) gas analyzer for hydrogen sulfide concentration in the range 5–200 ppb at the level of the limiting permissible concentration for a health zone is suggested. The gas analyzer is selective with respect to hydrogen sulfide.     

Effect of Covers for Soil and Water Conservation Using Tilting Flume

The effect of stone and vegetative covers was evaluated for soil and water conservation in a waterway on alfisols. Experiments were conducted on a hydraulic tilting flume under simulated flow (93 and 40 cm2?s?1) and slope (0.1, 1.0, 3.0, and 5.0%) conditions. The depth of soil was maintained at 0.35 m over a perforated bed to facilitate deep drainage. A comparative study of bare soil, stone cover (50%), and vegetative cover (50%) is made to evaluate soil loss, deep drainage, Manning’s roughness coefficient, and the Froude number. The study has revealed that stone cover is more effective than vegetative cover at lower discharge in reducing the flow velocity, and thereby soil erosion. Deep drainage has been reduced from lower to higher discharge for all the slopes with cover measures, including bare soil. It is found that cover measures are necessary beyond 3% slope in order to prevent rill erosion in alfisols.     

水溶气资源富集的主控因素及其评价方法探讨

水溶气是天然气的一种,其主要成份是甲烷。水溶气在地下的富集主要受温度、压力、水矿化度和储层水容量等因素的控制。储水量越大、水介质温压越高,地下可能储集的水溶气资源量越大。在水量和水介质温度压力条件相同的情况下,水的矿化度越低、水的溶气饱和度越高,水的储气量就越大。评价水溶气资源除应考虑地下天然气富集量之外,还应考虑钻探井的水日产量及采出地表后的释放气量。水溶气被采到地表时温压降低的幅度越大,释放出的气量越大。一般说来,每方水在地下含气饱和度在1～10m3之间;在我国东部沉积盆地这一数值为1～6m3。大庆长垣及其以西地区萨尔图、葡萄花和高台子组储层的水溶气量高达4500×108m3,依油气当量计算,相当于一个储量超过4.5×108t的大油田。在我国,水溶气具有广阔的勘探前景。     

乳化降粘剂SB-2乳化稠油机理研究

实验研究了用表面活性剂SB 2乳化稠油降低粘度的几个机理性问题。SB 2是胜利油田开发的稠油乳化降粘剂 ,为脂肪酸改性的具有多官能团的钠盐型阴离子表面活性剂。根据用duNo櫣ｙ法测定的表面张力曲线 ,SB 2在蒸馏水中的临界胶束浓度为 0 .16 g/L ,在模拟地层水 (TSD =15 .8g/L ,含Ca2 0 .6 g/L ,含镁 0 .2g/L)中的为0 .0 2 4 g/L。产自胜利油田不同区块 7口井、5 0℃粘度为 3.0× 10 3 ～ 3.3× 10 5mPa·s的稠油 ,与浓度 3～ 8g/L的SB 2地层水溶液在油水体积比 7∶3及一定温度 (5 0～ 70℃ ,视井温而定 )时形成粘度 <30 0mPa·s的O/W乳状液 ,稠油粘度较高时所需的SB 2浓度较高。用ESI MS方法测定了在 5 0℃形成的O/W稠油乳状液水相和油相中SB 2浓度 ,得到下述结果 :在相同稠油和油水比条件下 ,SB 2初始浓度较高时 ,乳状液水相和油相中SB 2浓度也较高 ,粘度不同的 2种稠油与同一浓度SB 2地层水溶液形成的乳状液 ,油水比越大 ,油相中SB 2浓度越小 ,水相中SB 2浓度则相同 ,油水比也相同时SB 2在油相中的浓度也相同。用微量热法测定了一种稠油与SB 2地层水溶液乳化时的热效应 ,乳化过程为放热过程 ,乳化热随水相SB 2浓度、油水比和乳化温度增高而增大。图 6表 1参 6。     

坡面侵蚀中径流含沙量测量方法研究与展望

土壤侵蚀中的径流含沙量是衡量坡地水土流失的重要参数之一，只有合理测量坡地径流中的含沙量才能为水土保持提供有利的依据，同时为验证土壤侵蚀预报模型提供基本参数。本文从测量原理出发，对含沙量各种测量方法的适用环境、测量精度及其局限性进行了比较全面的分析，重点研究了坡面径流含沙量的测量方法。研究结果表明目前测量含沙量的方法在坡面侵蚀动态水流含沙量的测量中存在只能静态测量的问题。目前电解质脉冲法在测量坡面薄层水流流速中做出了有益的探索，研究发现水流速度、泥沙的弥散系数与含沙量之间存在着相关关系，用此方法测量含沙量将有可能实现含沙量的动态测量。     

酸性料浆浓缩无干燥流程生产MAP的工艺剖析

针对传统的以中低品位磷矿为原料用料浆法生产MAP的能耗较大等问题，提出了酸性料浆浓缩无干燥流程生产MAP新工艺。即先把W（P2O5）=22％～25％的湿法磷酸用氨中和到n（NH3／H3PO4）=0．4～0．6，该酸性料浆在多效蒸发器中浓缩至W（H2O）=8％～10％，然后把中和到n（NH2／H3PO4）=1．00～1．05所需的氨在成粒过程中加到浓缩后的酸性料浆中，利用中和反应热把其中的水分闪蒸掉，从而取消了干燥工序，且无含氟废气排放。通过工艺计算，剖析了含水率在1％以下的MAP产品组成及该新工艺的可靠性，若传统工艺的MAP装置采用该新工艺，其主要设备的生产能力可增加30％～40％，但加热器的材料须采用904L或Sanicro28。     

碎石桩复合地基受力机理探讨

根据理论研究与实测资料的分析比较，表明当复合地基的应力在桩、土之间的分配过程趋于稳定时，地基中应力的分布与集中已接近结束，此时的地基承载力便是极限承载力，复合地基的受力过程中分为三个阶段，其破坏类型与应力分布是否充分的程度有关，从而对复合地基的受力机理作了有益的探讨。