In fact, if there were no boilers there would be no examinations, as the laws are framed, certificates issued and steam boiler inspection companies formed to assure the public safety in life, limb and property, from the dangers arising from so-called mysterious boiler explosions.
Hence an almost undue proportion of engineers’ examinations are devoted to the steam boiler, its management and construction. But the subject is worthy of the best and most thoughtful attention. Every year adds to the number of steam boilers in use. With the expanding area and growth of population, the number of steam plants are multiplied and in turn each new steam boiler demands a careful attendant.
There is this difference between the boiler and the engine. When the latter is delivered from the shop and set up, it does its work with an almost unvarying uniformity, while the boiler is a constant care. It is admitted that the engine has reached a much greater state of perfection and does its duty with very much more reliability than the boiler.
Even when vigilant precautions are observed, from the moment a steam boiler is constructed until it is finally destroyed there are numerous insidious agents perpetually at work which tend to weaken it. There is nothing from which the iron can draw sustenance to replace its losses. The atmosphere without and the air within the boiler, the water as it enters through the feed-pipe and containing mineral and organic substances, steam into which the water is converted, the sediment which is precipitated by boiling the water, the fire and the sulphurous and other acids of the fuel, are all natural enemies of the iron; they sap its strength, not only while the boiler is at work and undergoing constant strain, but in the morning before fire is started, and at noon, night, Sundays, and other holidays it is preyed upon by these and other corroding agents.
These are the reasons which impress the true engineer with a constant solicitude regarding the daily and even momentary action of the steam generator.
Description.
The Steam Boiler in its simplest form was simply a closed vessel partly filled with water and which was heated by a fire box, but as steam plants are divided into two principal parts, the engine and the boiler, so the latter is divided again into the furnace and boiler, each of which is essential to the other. The furnace contains the fuel to be burnt, the boiler contains the water to be evaporated.
There must be a steam space to hold the steam when generated; heating surface to transmit the heat from the burning fuel to the water; a chimney or other apparatus to cause a draught to the furnace and to carry away the products of combustion; and various fittings for supplying the boiler with water, for carrying away the steam when formed to the engine in which it is used; for allowing steam to escape into the open air when it forms faster than it can be used; for ascertaining the quantity of water in the boiler, for ascertaining the pressure of the steam, etc., all of which, together with the engine and its appliances is called A STEAM PLANT.
The forms in which steam generators are built are numerous, but may be divided into three classes, viz: stationary, locomotive and marine boilers, which terms designate the uses for which they are intended; in this work we have to deal mainly with the first-named, although a description with illustration is given of each type or form.