Weighed water pumped to boilers, pounds

Dry

Dry

Water evaporated per pound of dry coal, boiler conditions, pounds.
Water evaporated per pound of combustible, boiler conditions, pounds
Equivalent evaporation, per pound of dry coal from and at 212°
Equivalent evaporation, per pound of combustible, from and at 212°
Dry coal burned per hour per square foot of grate surface, pounds
Total steam used by main engine, pounds

Total steam used by auxiliary machinery, as weighed, pounds. Steam used by main engine per hour, per indicated horse-power developed, pounds

16232

8634

Total steam used (all machinery in use) per hour,
power developed by main engine
Dry coal used per hour per indicated horse-power to generate steam
necessary to run main engine only, pounds.

per

indicated horse

Dry coal used per hour per indicated horse-power, developed by main engine, to generate steam required to operate all machinery in use.

*Not in operation. Natural Draft. Run of Mine, Pittsburg bituminous.

usual pressure without their aid. The average hourly weight of condensed exhaust steam collected during five hours of the test, with the feed pump and steering engine only in use, amounted to 1685.4 pounds. For the purpose of fixing the steam economy of the feed pump during the last two and one-fourth hours of the test, the steam-steering engine was thrown out and the ship steered by hand. Under the latter conditions, an average of 1174.7 pounds of condensed exhaust steam per hour resulted.

During the entire test on July 23, the only auxiliary machinery in operation was the feed pump and fire-room blowers.

TESTS OF A BABCOCK & WILCOX BOILER BUILT

FOR THE U. S. S. " CINCINNATI”*

In the annual report of the Chief of the Bureau of Steam Engineering for 1900 there is published a report of tests made on one of eight new boilers built by the Babcock & Wilcox Company for the "Cincinnati," by a board composed of Lieutenant-Commander A. B. Willits and Lieutenant B. C. Bryan, U. S. N. These tests were made June 15 to 22, 1900, at the works of the builders, Elizabethport, N. J., and the following synopsis includes all but the detailed tabulations from which the important results given were deduced.

DESCRIPTION OF BOILER AND APPURTENANCES

The boiler is of the Babcock & Wilcox new marine type, composed entirely of wrought steel, the point of difference between it and the older type of this make of boiler being in the arrangement of baffle plates (as shown in the sectional view on the following page) which compel the products of combustion to pass three times across the tubes before entering the up-take. The small tubes are 2 inches outside diameter, while the bottom tube in each section or element, is 4 inches outside diameter. The total heating surface is 2640 square feet.

The grate is an undivided area of 63.25 square feet, and is fired through four properly spaced doors.

BOILER DATA

Kind of boiler, Babcock & Wilcox-"Alert" type. Diameter of top drum, 42 inches, inside. Length of top drum, 12 feet. Tubes: total number, 565; length, 8 feet (525, 2 inches outside diameter, and 40, 4 inches outside diameter). Grate surface: length, 6 feet 84 inches; width, 9 feet 51⁄2 inches; area, 63.25. Grate surface reduced in tests Nos. 5 and 6, to 5 feet 6 inches; 52 square feet area. Heating surface: area, 2640 square feet; ratio to grate, 41.74:1. Per cent. waterheating surface, 100. Grate bars: kind, fixed. Smoke pipe: area, 7.876 feet; height, 48 feet above grate; ratio to grate, 1:8.03. Weight of boiler and all fittings except up-takes and smoke pipe:

Blower: kind, 60-inch Sturtevant, driven by belt from shop engines. Area of blower inlet, 9.62 square feet; outlet, 6.89 square feet. Feed water: kind, feed water heated by steam jet. Air heater: kind, two-pass; 3-inch tubes. Area of surface, 495 square feet. Feed pumps: kind, Worthington duplex; diameters of cylinders, 71⁄2 and 4 inches; 6-inch stroke. Other boiler appurtenances: steam jet.

The boiler was erected in a wooden structure built especially for the test and having the following dimensions: Length, 29 feet 2 inches; width, 17 feet 22 * Extracts from the Journal of the American Society of Naval Engineers, volume xii. (1900).

U. S. S. "CINCINNATI" AND "RALEIGH" EACH, EIGHT BABCOCK & WILCOX BOILERS, 8000 INDICATED HORSE-POWER

inches; height, 21 feet. This was made as nearly air-tight as possible, but contained several windows that could be opened or closed to regulate the amount of draft pressure. The blower was driven by belting from the main shop engines and ran continually.

An air heater was built in the up-take by means of which the waste gases imparted heat to the air on its passage to the ash-pit. This heater could be placed in and out of service at will by the use of a by-pass flue.

"CINCINNATI'S" BOILER-B. & W. "ALERT" DESIGN. SECTION SHOWING

PATH OF GASES

Seven tests were made in all. Six of these consisted of three pairs, in which the tests of each pair were made under similar conditions in every way except that of using the air heater, one being with and the other being without this heater, in order to define the economy due to its use. The last or seventh test was for maximum capacity, and was made without the air heater and with the full grate. Two pairs of tests, one at a consumption of about 20 pounds of coal and the other at about 35 pounds of coal per square foot of grate per hour, were made with the full grate surface in use. These tests will be found in tables of results numbered 1, 2-H, 3-H, 4, the letter H signifying that the air heater was in use during the tests. The grate surface was then reduced to 52 square feet, by a