Juice heating

Juice heating had been done until 1979 by employing tubular heat interchangers. They have scaling problems. SRI developed a direct contact heater (Wright, 1979) in which juice is rained into direct contact with steam in a vessel similar to a condenser. This inexpensive design has eliminated the cost of tube cleaning and also the deterioration of heat exchange performance which occurred after a few days' operation. The only drawback is the additional load placed upon the evaporator vessels, since the juice becomes slightly diluted.

Evaporators

Throughout the world the sugar industries employ quadruple or quintuple evaporator sets whereby juice in each vessel is heated by steam in a calandria through which juice passes in vertical tubes. The steam driven off from the boiling juice in one vessel is passed to the following vessel in the set, where it is used as the steam in the calandria of that vessel. In this way steam is used, in effect, five times over; each succeeding vessel operating at a lower pressure.

Technologists in the Australian sugar industry have created designs to improve the performance by giving special attention to tubes: their diameters, spacing, length, method of fixing, and materials. SRI has introduced new circulation paths in vessels by placing a number of larger diameter tubes in selected locations in the calandria.

Computer programmes developed by SRI are used by sugar mills in the design and re-arrangement of vessels in the evaporator sets. Australian researchers and mill technologists have also introduced a variety of methods of chemical treatment to minimise scaling and to chemically clean the vessels periodically, to maximise heat transfer through the tubes.

Pan boiling

Boiling of sugar syrups and molasses under reduced pressure in 'pans' enables the process of producing sugar crystals to take place at lower temperatures. The designs of pans and their operation varies throughout the world. Australian researchers at SRI in the 1960s introduced a radioactive ball into operating batch pans of various designs and traced their paths to establish circulation patterns. This resulted in better pan designs and improved circulation which gave reduced boiling times and production of more uniform crystals as desired by the market.

Part of the sugar-boiling research programme at SRI over a 20-year period was directed into continuous pan boiling. The successful result is a design which has given outstanding performance in Australia and which has been built overseas under licence (Broadfoot and Wright, 1981). Mill technologists have also completed a satisfactory installation with unique features.

Innovation index

Anderson and Stalker (1981) use the index to measure the propensity of an industry to adopt new innovations. A study of the sugar industry showed its index to be far higher than comparable food industries. This is explained by these authors to be partly due to the unimpeded intra-industry information transfer which has led to world-leading technological developments. It is also largely due to the enlightened approach by the industry in its support for research, including the establishment and continued financing of world-leading research organisations within the industry.

Australian Academy of Technological Sciences and Engineering