Boiler accessories; by American School of Correspondence & Leland Walter S

Author:American School of Correspondence & Leland, Walter S. [from old catalog]
Language: eng
Format: epub
Tags: Steam-boilers
Publisher: Chicago, American school of correspondence
Published: 1909-03-25T05:00:00+00:00

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fittings, when empty, should of course be known, so that the weight

of the water alone can be determined. With the hose removed from

the barrel, allow steam to blow through the pipe until it has become

thoroughly heated If the sampling pipe is long, it should be wrapped

with hair felt or some form of lagging, to prevent condensation during

the test. As soon as the pipe line has become thoroughly heated,

plunge the hose into the barrel and allow the steam to blow through

the water until it has become well heated. Shut off the steam, and

carefully note the weight and temperature.

Suppose W = Final weight of water in barrel;

w = Weight of cold, condensing water before steam is turned on; ti = Temperature of the cold water; h = Temperature of the hot water;

P = Absolute pressure of steam in steam pipe (gauge pressure + atmospheric pressure).

From the steam tables in the back of the book may be found:

q, the B. T. U. in one pound of the liquid contents of the moist steam; q lf the B. T. U. in one pound of the cooling water, before the steam was

added; q 2) the B. T U. in one pound of this water after the steam has been

added; r, the heat of vaporization corresponding to the absolute pressure— i e.,

B. T. U. given up by one pound of steam condensed into water.

If x equals the percentage of dry steam contained in the supply pipe, 1 — x will represent the amount of priming.

x (W — w) = the total amount of dry steam condensed;

(1 — x) (W — w) = the total amount of moisture brought into the barrel by the moist steam.

If q x equals the heat in one pound of cooling water, then q x w will equal the total heat in the barrel at the beginning.

For the same reason q 2 W will equal the total heat after the steam has been condensed, and q 2 W - q x w will equal the total amount of heat gained by the water in the barrel.

If r is the heat of vaporization, then r x (W-w) will equal the B. T. U. contained in the dry steam; and if q is the heat of the liquid corresponding to the same pressure, then q (1 - x) (W - w) will equal the B. T. U. contained in the moisture brought over by the steam. It is apparent that the sum of these two quantities will be the total number of B. T. U. brought from the steam main to the water barrel, and must be equal to q 2 W - q l w, the heat gained by the water in the

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BOILER ACCESSORIES

barrel. The solution of this equation will result in a formula which will save some mathematical computations.

That the method may be perfectly clear, let us first consider a numerical example in full.

Suppose w = 455 lbs.

W = 495 lbs.

h - 50° F.

h = 140° F.

P = 75 lbs.

q (from steam tables) — 276.

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