Fuel oil according to the analysis given under fuel has the heating value of .38 14,650 X .82 + 62,100 (.14-- — 20,412 8 B. T. U. per lb.
If it is desired to consider the heating value of the sulphur content, one pound of sulphur when completely burned will liberate 4,050 B. T. U. The weight of sulphur in one pound of the fuel is therefore multiplied by 4,050 and added to the sum of the heat liberated by the other constituents in determining the heat ing value of the fuel.
Water.—For many years, the water sup ply was considered one of quantity only, re gardless of the kind. Quantity of course is of prime importance, but considerable expense in maintenance and operation can be saved by scientific handling and treatment of the water used. In certain localities the waters, though unfit for drinking purposes, may not contain substances which make them undesirable for boiler use. Some waters though very good for drinking purposes contain material which either cause the formation of soft scale, hard scale, corroding or foaming. Soft and hard scale are poor conductors of heat, and upon collecting .in the tubes and on the heating surfaces sur rounding the firebox reduce the heat trans mission besides clogging up the passages. As the heat transmission is retarded the boiler plates next to the hot gases and the tubes be come overheated which causes leaks and trouble with the engine's cylinder parts and steam passages. Relief is found by constant washouts, but this is an expensive method to pursue. It causes delays, layovers of consid erable time and is hard on the life of the boiler in that cooling and heating up cause unequal expansion in the various parts which results in a loosening at the connections.
Foaming is the most troublesome and most difficult to remedy. Broken cylinder parts, blowing out of packings, cutting of reciprocat ing parts are quite frequently the result of foaming. Quite often foaming causes trouble with the fire-box sheets and tube sheets. Con siderable waste of water and heat occurs in that water is carried along with the steam to the cylinders, especially when the boiler is be ing forced as in climbing grades.
Treatment of In the case of soft scale due to the presence of lime carbonate and magnesia carbonate it is advisable to neu tralize with slaked lime and give the boiler washouts frequently. Hard scale is due to the presence of lime and magnesia sulphates. Foaming is possible as an after trouble. Soda ash with slaked lime acts as a remedy and the boilers should be washed out frequently. Changing of the water and blowing out is also advisable whenever possible.
Acids and chlorides in the water cause cor rosion and foaming. The boiler should be closely inspected frequently, blown out and the water changed. Slaked lime or soda ash are helpful in relieving this trouble.
Foaming is frequently caused by the pres ence of alkali and mud in the water fed to the boiler. Diluting the water with other waters quite often gives relief. Distillation alum acts as a neutralizer. The boiler should be blown out often and the water changed frequently.
Where water of sufficient purity is not avail able for the boilers many of the railroad com panies are finding it necessary to render the available supply suitable by treatment and water-softening plants are being installed at the watering stations and terminals. Most of the companies employ chemical engineers to make a study of different water's used along the right of way and treat the waters, figuring the .cost as against the interest and depreciation on the additional locomotives required for their service. Cost of cleaning the boilers, decrease in efficiency and capacity are also balanced up.
The Locomotive Firebox and Combus tion The locomotive boiler consists essentially of a rectangular firebox and a cylindrical shell through which numerous tubes pass from firebox to the smoke box, terminating in tube sheets. The products of combustion after passing the length of the tubes enter the smokebox and pass up the smoke stack with the exhaust steam from the steam cylinders. A forged steel ring joins the fire box with the outer shell. Near this ring are several hand holes for cleaning out the space between the shell and the firebox. This space is commonly called the water leg. All plates of the boiler and firebox that are not of cylindrical shape require staying to keep them in place. For example, the cylindrical shell of a tubular boiler does not require staying or bracing as the internal pressure tends to keep it cylindrical. Flat surfaces tend to bulge and must be held in place. The placing of stays and the arrangement plays an important part in the design of a boiler and must be worked out for each special type. Many dif ferent methods of staying will be found, and there are quite often several ways of staying the same kind of surface. The firebox and fiat ends of the boiler require staying. How ever, a portion of the tube sheets are suffi ciently held in place by the tubes. The water leg is stayed by screwed stay bolts riveted at the ends. These stay bolts are likely to crack or break off on account of the expansion of the firebox. In order to detect such a failure the stay bolts are often drilled from the outer end nearly through to the inner end. In case of failure steam will blow out the defective stay and thus give warning. The crown sheet of the firebox is exposed to intense heat while covered with but a few inches of water. The staying of the crown sheet is one of the most difficult problems met in locomotive boiler con struction. To avoid the difficulties of staying the crown sheet, the firebox end of the boiler shell is sometimes made flat on top. Tubes for a locomotive boiler are as a rule made smaller than for stationary boilers and are spaced much more closely. Two-inch tubes are used generally, although in some cases smaller tubes have been used. The boiler is fastened rigidly to the frame of the locomotive at the smoke box end. A small longitudinal motion on the frame at the firebox end is provided for by expansion pads.