Excerpt from Boiler Furnaces
The process of combustion is affected by so many different physical conditions that in order to either design a furnace or superintend its operation, it is necessary to fully understand the chemical changes which take place. Among the physical conditions referred to above may be included strength of draft, depth of fuel bod, form of furnace, and the various methods of firing employed. So far as the generation of steam is concerned, combustion may be considered as the chemical union of oxygen with the various elements of the fuel for which it has an affinity. This union produces a definite amount of heat per pound of combustible, depending upon the clement with which the oxygen combines.
The elements contained in the usual forms of fuel, which enter into the process of combustion, are oxygen, carbon, hydrogen and sulphur. There are various other constituents present which have no fuel value, such as the Iron, silicon, etc., found in coal. These usually exist in small quantities, and are classed as impurities. They produce a certain waste in the form of ash, and in addition to this, their temperature must be raised to that of the fire before becoming separated from the other elements, and more or less of this heat Is lost as they are discharged from the fire.
Oxygen is the universal element of combustion; it is an invisible gas and makes up about one-fifth the volume of the air in an uncombined state. It is also found in water, being combined with hydrogen in this case, and in coal and other fuels of vegetable origin, combined with carbon and hydrogen. It is usually present in coal in amounts varying from 1 to 25 per cent, according to the grade.
Carbon is a solid, and is found in a pure state In the form of graphite and charcoal. In its crystalized state it forms diamonds. It is also found In oils of various kinds, and In tar, combined with hydrogen. Vegetable products of all kinds contain carbon In combination with oxygen and hydrogen, and it is the principal heat-producing element In coal and other fuels, Including liquids and gases.
Hydrogen is a combustible gas, and exists in nature only in combination with some other element. Water can be separated into oxygen and hydrogen by passing a current of electricity through it. Another method of producing the same result is to pass steam through a bed of white-hot coal. The oxygen in this case unites with the carbon, forming carbon monoxide, leaving the hydrogen In a free state. A mixture of carbon monoxide and hydrogen is called water gas and under certain conditions is used for lighting and heating.
About the Publisher
Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com
This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works. Это и многое другое вы найдете в книге Boiler Furnaces (Classic Reprint)