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in the up-take was abandoned, and its equivalent heating surface added to

that in the boiler; the cost of up-keep in a marine boiler economizer, due to its inaccessible situation and essen

tial piping, valves, etc., amounting to

more than the advantages derived from its use.

In 1899 this design was further improved by the use of longer tubes, increasing the length of the furnace, and by a system of vertical baffles, in connection with a roof of light fire tile placed on the lower row of tubes. This arrangement of heating surface reduced the height of the boiler, increased

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the furnace capacity and permitted thorough

dusting of the

tubes without

BABCOCK & WILCOX, 1896
PATENTED

opening the tube doors at the front or rear.

The first boilers constructed on this plan were built for the U. S. S. "Alert," and installed in that ship at Mare Island Navy Yard, California. Hence the design is known as the "Alert" design.

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END VIEW OF BABCOCK & WILCOX MARINE BOILER SHOWING CLEANING DOORS-PATENTED

DESCRIPTION OF THE BABCOCK & WILCOX BOILER

T

HE construction of the Babcock & Wilcox marine boiler embodies the same well-known principles as the successful land or stationary type; freedom of circulation, and economy when forcing, being important factors of both designs.

The tubes forming the heating surface are divided into vertical sections and, to insure a continuous circulation in one direction, are placed at an inclination of 15 degrees with the horizontal.

FORGED STEEL HEADER HANDHOLE COVERING GROUP OF FOUR 2-INCH TUBES

By distributing the surface into sectional elements, all danger from unequal expansion due to raising steam quickly, or to sudden cooling, is at once over

come.

Each section is made up of a series of straight tubes expanded at their ends. into corrugated wrought-steel boxes known as headers. As the headers are staggered, the tubes are so disposed that lanes for the sudden escape of the products of combustion are prevented. The hot gases are therefore completely broken up in their passage across the heating surface.

The side sections are continued down to the level of the grate, the tubes being replaced by forged steel boxes of 6inch square section at the furnace sides. These boxes are located one above the other at the same angle as the tubes; they take the place of brick work; ensure a cool side casing; prevent the adherence of clinkers, and are of sufficient thickness to withstand the wear and tear of the fire tools.

Extending across the front of the boiler and connected to the upper ends of the headers by 4-inch tubes, is a horizontal steam and water drum of ample dimensions.

As the upper ends of the rear headers are also connected to this drum. by horizontal 4-inch tubes, each section is provided with an entirely independent inlet and outlet for water and steam.

Placed across the bottom of the front header ends and connected thereto by similar 4-inch tubes, is a forged steel box of 6-inch square sec

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UNITED STATES BATTLESHIPS "FLORIDA " AND "UTAH "-BABCOCK & WILCOX BOILERS, 45,000 I. H. P.

tion. This box, situated at the lowest corner of the bank of tubes, forms a blow-off connection or mud drum through which the boiler may be completely drained.

The circulation of the water is as follows: Heat being applied to the inclined tubes and vapor formed, the water and steam rise to the high end and flow through the up-take headers and horizontal return tubes to the steam and water drum, the path of both water and steam being short and direct; the water evaporated in the tubes and that carried along by the currents induced by the steam bubbles being replaced by water flowing directly from the bottom of the drum downward through the front headers, or down-takes, and into the tubes, part of this water to be in turn evaporated.

Upon entering the drum the steam and circulating water are directed against a baffle plate, which causes the water to be thrown downward, while the steam separates and passes around the ends of the baffle plate to the steam space, from which it is conducted by a perforated dry pipe to the stop valve.

By a roof of light fire tile, supported upon the lower tubes and extending part way over the furnace, the gases evolved from fresh fuel are compelled to flow toward the rear of the boiler, passing over an incandescent bed of coals and under the hot tile roof.

As the furnace increases in height approaching the bridge wall, the gases have both space and time in which to mix thoroughly and burn before entering the bank of tubes forming the heating surface. By this arrangement a high furnace temperature is established, which is acknowledged by all authorities to be the essential requirement of boiler economy.

The circuitous route which the gases are compelled to follow, in crossing the heating surface three times before exit, causes them to impart to the tubes the greatest possible amount of heat.

The distance traveled by the products of combustion in contact with the heating surface is about sixteen feet, hence good economy is maintained with high rates of combustion, and a low up-take temperature assured; the interval for the absorption of heat, so necessary for economy, being longer than in any other type of marine water-tube boiler. The temperature of the gases, taken at different places in their path to the funnel, will be found under "Tests of Babcock & Wilcox Marine Boilers."

All tubes are constructed of seamless steel and are extra heavy. Opposite the end of each tube is an opening, or hand hole, in the header, through which the tube may be examined, cleaned, plugged or renewed; it is closed by a forged-steel plate into which is riveted a 1-inch stud. This plate is faced, and is drawn to a faced seat by a forged-steel bridge and nut, the joint being made on the inside of the header, by means of a thin gasket.

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