SRI's renowned expertise in sugar crystallisation encompasses extensive experimentation, performance modelling and equipment design.
Our key capabilities and recent projects include:
- Fundamental knowledge of the growth rates of sugar crystals for high purity and low purity massecuites in evaporative crystallisers and for low purity massecuites in cooling crystallisers;
- Measurement of circulation velocities and heat transfer coefficients of massecuites in evaporative crystallisation pans. The data are beneficial in defining the circulation characteristics of different designs of pans, and have been used to validate CFD models of natural circulation vacuum pans. SRI has developed designs for batch pans (stirred or natural circulation);
- Development of an improved design of stirrer for central downtake (fixed calandria) pans. The design results from CFD modelling of massecuite flows in these pans;
- Development of the SRI and T-SRI continuous vacuum pans for producing A, B and C strike massecuites and high grade seed massecuite. The pan designs are modular in construction. This provides benefits in reducing steam consumption and allows faster boilout procedures to be implemented;
- Design of a C sugar magma conditioning system to dissolve fine crystal fragments and recrystallise sucrose to prepare a crystal seed stream for batch or continuous pans;
- Development of radio frequency brix measurement transducers for measuring the massecuite brix in vacuum pans. The SRI Sucromax sensor measures the sucrose content of process feed streams to the pan stage which, when combined with brix measurement, provides on-line purity measurement of the process stream;
- Modelling analysis of pan and fugal station operations to determine mass flow quantities, massecuite stream compositions, and steam consumption rates for various crystallisation flowschemes. The investigations have included financial analyses of different flowschemes to determine the most economical process configuration for the production of sugars of different polarizations;
- Development of a digital image crystal sizing system to allow measurement at-line of the mean size and spread of sizes of crystals taken from pans;
- Development of a pan agitation system, which utilises the incondensible gases from the calandria and releases these into the base of the pan. The system increases the circulation rate of massecuite, with the benefit of increased heat transfer, improved uniformity of conditions and increased productivity;
- Development of a supervisory control system to assist pan and fugal station operators to make improved decisions for managing the stations. The system's benefits are increased productivity, improved quality of sugar production, increased recovery of sucrose from molasses and reduced steam consumption. The system is still under development;
- Determination of a vertical crystalliser design (SRI design) for the cooling crystallisation of C massecuite. The design incorporates a strong emphasis on avoiding short-circuiting of massecuite from inlet to outlet - a common problem in vertical crystallisers; and
- Formulation of a model for predicting the cooling crystallisation of C massecuite. Important variables are mother molasses impurity/water ratio, surface area of the crystals, massecuite temperature and the shear rate imposed by the stirring equipment. This model has been used extensively to plan upgrades of cooling crystalliser stations.
