boiler incrustation defined in 1909 yearboiler incrustation - boiler incrustation (BOILER COMPOSITIONS);
boiler incrustation - The extent and character of the solid matters in the various natural waters at the disposal of the boiler-owner (the so-called natural mineral waters, such as those of Bath, Buxton, and Harrogate, are here left out of account) vary considerably, and depend upon the nature of the ground. Thus in limestone districts, as in Derbyshire, or in chalk districts, such as in the London district, there is much carbonate of lime in the water; in slate and granite districts, as in Cumberland and Cornwall, the waters are fairly pure, and contain very little matter in solution; in Yorkshire, where there is a good deal of magnesium limestone, the waters contain much magnesia in solution; river and brook waters which flow over the surface are more charged with vegetable organic matter than are well and spring waters. The chief impurities usually present are the carbonates of lime and magnesia, and the sulphates of the same two earths; common salt (sodium chloride) is present in all waters; silica is a common constituent; some waters contain magnesium chloride.
The analyses of various boiler waters that have come under the writer's notice are given in the table below.
The figures are expressed in grains per gallon.
These figures serve to demonstrate how wide is the variation in the waters that owners of boilers in various districts have to deal with. The analyses of scales from various waters, also show this great variation.
In A, B, and C, it is the carbonates of lime and magnesia which form the great bulk of these scales, while in D, E, and P, it is the sulphate of lime. There is some difference in these two classes of scales; those which contain the carbonates chiefly are usually brittle and pulverulent, while if there is but little sulphate, as in A and C, then the scale may be powdery rather than adherent. On the other hand, owing to the more crystalline nature of lime sulphate, the scales, in which it occurs principally, are hard and crystalline, difficult to break up and remove.
The chief scale formers which boiler owners have most to dread are the carbonates and sulphates of the two earth metals, lime and magnesia, particularly the sulphates, because these form the hardest scale. Alkaline salts are not of much moment, while silica and other substances are usually present in too small an amount to exert any material effect. The question arises, Can the formation of scale be prevented in any way?
There are two ways in which this is done at the present time. The best plan is to adopt some method of softening the water - that is, removing the lime and magnesia compounds before the water goes into the boiler. This is the better plan but it necessitates a special plant, to the cost of erection of which, and the labour involved in attending to it, many boiler owners object.
The next method is to add to the water in the boiler some substance which shall so react with the constituents of the water as to change their properties, converting them from scale formers into sludge by periodical opening of the blow-off taps. Many boiler users do not give as much consideration as they might do to the quantity of solid matter they put into their boilers, and what becomes of it.
See the most common problems of the boiler incrustation:
near boiler incrustation in Knolik
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