100

Where F = per cent of fiber in cane, S = per cent sucrose, G = per cent
glucose, W = per cent water.

This formula gives the total available heat per pound of bagasse, that
is, the heat generated per pound less the heat required to evaporate its
moisture and superheat the steam thus formed to the temperature of the
stack gases.

Three samples of bagasse in which the ash is assumed to be 3 per cent
give from the formula:

F = 50 S and G = 4.5 W = 42.5 B. t. u. = 4183
F = 40 S and G = 6.0 W = 51.0 B. t. u. = 3351
F = 33.3 S and G = 7.0 W = 56.7 B. t. u. = 2797

A sample of Java bagasse having F = 46.5, S = 4.50, G = 0.5, W = 47.5
gives B. t. u. 3868.

These figures show that the dryer the bagasse is crushed, the higher the
calorific value, though this is accompanied by a decrease in sucrose.
The explanation lies in the fact that the presence of sucrose in an
analysis is accompanied by a definite amount of water, and that the
residual juice contains sufficient organic substance to evaporate the
water present when a fuel is burned in a furnace. For example, assume
the residual juice (100 per cent) to contain 12 per cent organic matter.
From the constant in formula,

12x7119 (100-12)x972
------- = 854.3 and ------------ = 855.4.
100 100

That is, the moisture in a juice containing 12 per cent of sugar will be
evaporated by the heat developed by the combustion of the contained
sugar. It would, therefore, appear that a bagasse containing such juice
has a calorific value due only to its fiber content. This is, of course,
true only where the highest products of oxidization are formed during
the combustion of the organic matter. This is not strictly the case,
especially with a bagasse of a high moisture content which will not burn
properly but which smoulders and produces a large quantity of products
of destructive distillation, chiefly heavy hydrocarbons, which escape
unburnt. The reasoning, however, is sufficient to explain the steam
making properties of bagasse of a low sucrose content, such as are
secured in Java, as when the sucrose content is lower, the heat value is
increased by extracting more juice, and hence more sugar from it. The
sugar operations in Java exemplify this and show that with a high
dilution by maceration and heavy pressure the bagasse meets all of the
steam requirements of the mills without auxiliary fuel.

A high pe