International Sugar Journal
The Blackboard

The use of lead salts in the laboratory [Registered]

Browne & Zerban (1948) quote Scheibler who in 1875 investigated a “double dilution” method to reduce the error caused by the lead precipitate in saccharimetry; Pellet & Sachs in 1880 […]

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Entrainment – Sampling & Analysis [Full subscriber]

Sampling condensed vapours and condenser waters is never easy. Beale (1959, 1962) and Claire (1965, 1967) mention practical difficulties encountered. Vapour sampling involves iso-kinetic (constant velocity) principles which require sophisticated equipment to obtain representative condensed vapour samples. Most workers have sampled condensates and condenser waters, using simplified sampling equipment. One of the problems associated with condenser waters is that the inlet water usually contains sugar. The large volumes of water and low concentrations of sugar can cause serious errors. A simple calculation illustrates the difficulty; we assume that the condenser inlet and outlet waters contain 70ppm of sugar, that 1 ton of vapour requires 30 tons of inlet water, and that the analytical precision is ±1ppm.

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Entrainment – basic concepts [Registered]

Spencer & Meade (1948) state that during evaporation there is always the possibility of sucrose loss due to the carrying over, or entrainment, of small drops of juice or syrup […]

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Brix free water – the concept [Registered]

Heintz in 1874 showed that when air-dried and sugar free beet “marc” (the beet components remaining after complete aqueous extraction of the soluble constituents) is placed in a sugar solution […]

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Milling performance [Registered]

An interesting aspect of milling is the evaluation of the performance of each mill in the tandem. Early (1921-1931) analytical techniques are described in Browne & Zerban (1948); sampling is discussed in the SASTA Laboratory Manual (1985). Material balances across milling tandems normally use 4 main assumptions which are not all rigorously correct:

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Chemical Cleaning of Evaporators [Registered]

Literature on the chemical cleaning of evaporators was available in 1929 (Spencer & Meade; 1948); in most cases sodium hydroxide and soda ash were boiled individually or as mixtures in the vessels which were then drained and washed. A boiling with hydrochloric acid would follow if necessary. Spraying techniques in Java and Hawaii were seen to be more economical in terms of chemical quantities. Fermented molasses was used in Queensland in the early 1930’s, and Honig (1953) quotes results obtained in 1949 from Taiwan.

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Mechanical cleaning of evaporators [Registered]

Although mechanical cleaning of evaporators must have been used in many cane sugar industries, the topic is not well covered in the literature. There are a number of reasons for […]

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Evaporator scale [Registered]

Spencer & Meade (1948) state that “The greatest limiting factor to all evaporators is the fouling of heating surfaces”; they also include the results (on the right) obtained by analysing […]

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Cane cleaning [Registered]

The cleaning of harvested sugar cane to remove tops, trash, rocks and soil is not a new concept: Spencer & Meade (1948) describe a dry cane cleaning plant used in […]

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Analysis of sugar mixtures (part II) [Registered]

For the analysis of sugar mixtures Browne & Zerban (1948) use total solids by drying, which is an accurate but lengthy procedure; reading a refractometer Brix is simpler but requires […]

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