Rheology and pipeline transportation of final molasses

Abstract

The rheology of final molasses at temperature (T) ranging from 20 to 70°C was characterised with a cone and plate viscometer. The shear-thinning power law model described its flow behaviour very well. In the Arrhenius plot of log viscosity at given shear rate versus 1/T, two linear regions were apparently displayed. It showed that the viscosity is relatively more sensitive to temperature between 20 and 50°C. The rheological data were used to calculate pumping energy consumption, P (kW-h/t-km), an important cost parameter in the feasibility study of long distance pipeline transportation. As the molasses viscosity is inherently high at the ambient temperature of about 30°C, its transportation in pipeline will be in the laminar regime for an average throughput of 50 t/h using the normal pipe size range of between 5 and 24 in. For transport in the turbulent flow regime, the temperature, throughput and pipe diameter must all be high. Normally the P decreases with increasing diameter and temperature, and with decreasing throughput.