OLR Abstract

The following is the abstract for the presentation on the Rheology Solutions OnLine Rheometer

Title: Online Rheometry of Complex Process Fluids

Tim Kealy – Project Director. OnLine Rheometer Group, Rheology Solutions
Pradipto Bhattacharyya – Senior Scientist, OnLine Rheometer Group, Rheology Solutions


The potential for using rheology in process industries for improving performance and product quality is well recognised. Typical industrial practices involve:

i)  Sampling small amounts of process fluids for rheological analysis with laboratory instruments. This can involve a significant delay between sampling and analysis – increasing processing time and consumption of resources. In addition, there is a risk that a single sample weighing only a few grams may not be representative of the bulk. Furthermore, many materials have a time- and shear history-dependent structure and delays, sample handling and environmental conditions to which the material is exposed in transit from pipe to lab can impact on the veracity of the laboratory measurement apropos the in-pipe rheology.

ii)  On-line techniques, usually torsional measurements on a vibrating probe, provide a single-point measurement in the high shear portion of the material flow curve.  These measurements are usually treated as a QC ‘number’ and monitored for deviation because it is difficult to confirm the accuracy of the measurement. Risks with these measurements include the difficulty in predicting fluid behaviour from a single, high shear measurement, often of unknown accuracy.

In this presentation we introduce an OnLine Rheometer (OLR) that is capable of providing continuous rheometric information, on-line and in real time. In- or on-line measurements remove many of the risks associated with delays, sample handling and environmental exposure. The OLR can provide viscoelastic data (G’, G’’, d, h*) for the material in the pipe, providing a characteristic curve over a wide range of frequencies (1-100Hz). The accuracy of these measurements can easily be compared to those measured in the laboratory.

We use a 2.5% solution of carboxymethyl cellulose (CMC) as a test fluid and obtain its linear viscoelastic characteristic while it is circulated in a pipe-loop equipped with the OLR and compare the performance of the OLR with those obtained using a laboratory rheometer as well as with other typical online instruments.  The OLR performs well with respect to comparisons with laboratory measurements and may be used for QC in a similar way to traditional in-line monitoring, though clearly the OLR measurements are more powerful because a characteristic curve is generated.