AR—G2型流变仪

粘度是流体的重要物理性质之一,其数值的准确与否对制定油气田开发政策具有重要意义。利用AR—G2型流变仪对西峡沟原油流变性能进行研究,确定其原油具有明显的粘温特性,为剪切变稀型流体。     

AR—G2型流变仪分析技术的应用

粘度是流体的重要物理性质之一,其数值的准确与否对制定油气田开发政策具有重要意义.AR-G2流变仪是应力控制流变仪最新的产品,利用其对西峡沟原油流变性能进行研究,确定其原油具有明显的粘温特性,为剪切变稀型流体.几组实验数据说明AR-G2流变仪能够适应吐哈油田原油流变性能的测定.     

AR-G2型流变仪

粘度是流体的重要物理性质之一,其数值的准确与否对制定油气田开发政策具有重要意义。利用AR-G2型流变仪对西峡沟原油流变性能进行研究,确定其原油具有明显的粘温特性,为剪切变稀型流体。     

布拉本达通用流变仪的调试与标定

布拉本达通用流变仪Brabencler Rheotron是一典型的旋转流变仪用从测定牛顿型或非牛顿型流体的切应力、剪切粘度和第一法向力差以及振荡剪切响应等流变参数。本文根据该仪器的结构特征和流变测量学的基本原理,就速度校正、温度控制、转矩和法向力线性响应以及其他测量元件技术特性的鉴定提出校核与调整的方法;并且归纳出标定仪器常数的计算方法,以及适宜于该仪器的求取假塑性流体剪切流变参数的非牛顿校正方法。这些结果对于其他类型的旋转流变仪或粘度计的校正与标定也具有参考价值。     

高粘度煤泥加压旋转流变仪的标定与应用

高粘度煤泥流变特性是影响其高压管道输送阻力的一个重要因素．故研制加压旋转流变仪测量高粘度煤泥不同压力时的流变特性。标定加压旋转流变仪,用于测试压力对流变性的影响。使用加压旋转流变仪测试浓度75％煤泥的剪切应力和剪切速率．绘制了煤泥不同压力时的流变曲线和表观粘度曲线,通过分析确定了煤泥常压下是宾汉型流体,加压下为屈服假塑性流体。     

基于AR 2000ex型流变仪的润滑脂性能研究

不同基质的润滑脂由于其成分的差异,受到剪切后黏度的变化程度不同。利用AR2000ex型流变仪研究3种不同基质的润滑脂在不同工作阶段的流变性能。结果表明,通过控制剪切速率得到特定条件下的流变曲线,可以分析出润滑脂在性能上的差异;锂基润滑脂无论是停止工作时的稳定性,还是工作时受剪切情况下的润滑性能,都优于钙基润滑脂和尿素基润滑脂;润滑脂的流变曲线基本符合Herschel-Bulkley模型,而且润滑脂的触变性表现为影响润滑脂的屈服应力。     

高浓度粘稠物料加压旋转流变仪的研制与标定

高浓度粘稠物料(如原生煤泥、造纸污泥等一类工业副产品或固体废弃物)流变特性的测定在其管道输送系统的设计中有重要意义。这种粘稠物料若无添加剂作用在常压下是一种分散结团物料,不具备流体特性,无法采用一般旋转流变仪对其流变特性进行测试。因此研制出一种新型加压旋转流变仪(最高压力20MPa),将物料封闭加压,维持管道输送时的工况,保持其流体形态,从而达到物料加压流变特性测试的目的。该仪器的标定与使用结果表明其达到了设计要求,数据采集方便,测量自动化程度较高。     

剪切历史对长庆含蜡原油流变性的影响研究

对不同剪切历史作用后的长庆含蜡原油流变性能进行实验研究.通过改变剪切时间和剪切速率,模拟了管流现场的剪切历史作用,通过测量不同剪切历史作用后油样的凝点和粘度变化,研究了剪切历史对长庆含蜡原油流变性的影响规律,并针对剪切作用对含蜡原油流变性影响的作用机制进行了分析.结果表明:低温低速长时间的剪切作用对含蜡原油流变性能影响较大,低速剪切会增大含蜡原油的凝点和粘度,长时间的高速剪切作用会优化含蜡原油的流变性能.     

一种新型Couette流变仪的力矩修正和粘度测量误差分析

为准确计算得出新型Couette流变仪工作段剪切力矩,通过对计算机采集的电机输出转矩进行校核,得出了电机输出转矩真实值;利用商业旋转流变仪测量,得出了实验流体标准大气压下的粘温关系,最后得出了修正力矩与雷诺数的关系。考虑到该流变仪在制造和数据采集中存在误差,利用误差传递计算方法得出了新型Couette流变仪在测量流体粘度时的误差范围。分析结果为进一步测量不同状态下流体的粘度和研究空化奠定了基础。     

可调压可视化微间隙Couette流变仪的研究及应用

采用精密的机械加工和独特的气动旋转密封技术,研制出可调压可视化微间隙Couette流变仪。外圆筒旋转内圆筒静止的特点,使该流变仪能产生剪切速率高达105/s数量级稳定的纯剪切流。利用商业旋转流变仪,测量试验用中、低粘度硅油在低剪切速率和不同温度下的粘度,应用粘温关系,推算出高剪切速率下粘性热使粘度下降的量,其值与微间隙Couette流变仪的测量结果较为吻合。在一定的切应力下,观察到淡水和中低粘度硅油在微间隙中发生剪切空化的现象,发现剪切空化的发生还强烈依赖于流体中气体的相对溶解量。     

Determination of friction factor of Algerian crude oil during flow in pipe-lines

Crude oil flow in the pipelines is a source of major problems with heavy substance deposits on the wall surfaces. This situation can lead to lines blocking. Therefore, it is mandatory to have information concerning the flow. For this purpose the rheological properties of the crude oil are needed in order to propose adapted solutions. This paper deals with the study of the rheological properties of Algerian crude oil at different temperatures as well as its flow in pipe. The experimental results obtained with a modern rheometer can be used to predict the crude oil transport characteristics. The crude oil rheogram shows a non-Newtonian behavior which can be described by the Ostwald law. The shear stresses computations obtained from an analytical model and the MPTT model are compared and give the friction factor distribution across the pipe section. The obtained results are presented and discussed.     

Rheological properties of lithium,lithium complex,and sodium greases

The rheological properties of two lithium, two lithium complex, and two sodium greases, all with the most common NLGI grade two, have been investigated. The greases are based on a mineral and a synthetic oil. The apparatus used was a cone-and-plate rheometer and an impacting-ball apparatus. The impacting-ball apparatus used a steel ball, which impacted a lubricated sintered carbide plate, to measure the shear stress-pressure coefficient, γ, of the lubricant. At pressures found in elastohydrodynamic contacts this coefficient determined the limiting shear stress. The γ-value thus affects the coefficient of friction and consequently, lower γ-value means less friction. The results from the impacting-ball apparatus showed that the γ-value was lower for the greases with a synthetic base oil and that the lithium greases gave a lower γ-value than the corresponding base oils. Results from the cone-and-plate rheometer showed the characteristic shear thinning behaviour of the greases and the influence of shear history and temperature. The results from the cone-and-plate rheometer have also been fitted to a four parameter rheological model.     

A sliding plate microgap rheometer for the simultaneous measurement of shear stress and first normal stress difference

A new generation of the "flexure-based microgap rheometer" (the N-FMR) has been developed which is also capable of measuring, in addition to the shear stress, the first normal stress difference of micrometer thin fluid films. This microgap rheometer with a translation system based on compound spring flexures measures the rheological properties of microliter samples of complex fluids confined in a plane couette configuration with gap distances of h = 1-400 μm up to shear rates of γ = 3000 s(-1). Feed back loop controlled precise positioning of the shearing surfaces with response times <1 ms enables to control the parallelism within 1.5 μrad and to maintain the gap distance within 20 nm. This precise gap control minimizes squeeze flow effects and allows therefore to measure the first normal stress difference N(1) of the thin film down to a micrometer gap distance, with a lower limit of N(1)/γ = 9.375×10(-11) η/h(2) that depends on the shear viscosity η and the squared inverse gap. Structural development of complex fluids in the confinement can be visualized by using a beam splitter on the shearing surface and a long working distance microscope. In summary, this new instrument allows to investigate the confinement dependent rheological and morphological evolution of micrometer thin films.     

Formulation,rheology and thermal ageing of polymer greases—Part I: Influence of the thickener content

The aim of this work is to show the correlation between polymer greases’ rheology and its formulation. The tested polypropylene (PP) thickened greases were evaluated regarding their thickener content and its effect on the rheological properties. An artificial ageing procedure was performed by heating fresh grease samples in an oven to study the thermal degradation. The ageing evaluation was performed through rheological measurements, FT-IR spectra, oil loss, bleed-oil viscosity changes and bleed rate. The rheology measurements were performed on a rotational rheometer, emphasizing on the storage and loss moduli values at the Linear Visco-Elastic (LVE) region. The flow curve of each grease was also measured. A modified Herschel–Buckley model was applied and the data was correlated to the thickener content.     

Rheological Properties of Extreme Pressure Greases Measured Using a Process Control Rheometer

A new process control rheometer (PCR) designed for use in industrial process flows has been used to measure the rheological properties of three extreme-pressure greases. The rheometer is a robust yet sensitive instrument designed to operate in an industrial processing environment in either in-line or on-line configurations. The PCR was able to measure rheological properties including the elastic modulus, viscous modulus, and complex viscosity of the greases which in an industrial flow application could be used as variables in a feedback system to control the process and the quality of the product.     

High pressure rheometer for in situ formation and characterization of methane hydrates

We present a novel setup for a high pressure rheometer operating with concentric cylinders geometry for in situ studies of hydrate formation and rheological characterization. The apparatus uses an external high pressure mixing cell to saturate water-in-oil emulsions with methane gas. The capability of mixing combined with a true rheometer design make this apparatus unique in terms of setup and sample formation. We have used the apparatus to form gas hydrates in situ from water-in-oil emulsions and characterize suspension rheological properties such as yield stress and shear-thinning behavior.     

高压智能旋转流变仪机械结构设计方案研究

给出高压智能旋转流变仪机械结构的设计方案,高压智能旋转流变仪能够在压力不超过35MPa的条件下测定各种流体的流变参数,为高浓度煤泥和其它物料管道输送实验台建立流变特性模型获得可靠的实验数据创造了条件.