Gas Heating

Gas Heating. Complete burning of a combustible gas affords a certain amount of heat, which may be usefully employed for various purposes. In recent times the heat obtained by the combustion of coal-gas has been utilised in many ways. For domestic use the gas has been introduced into specially-constructed grates and there burnt by means of suitable burners, so that their heat may be given to blocks of asbestos, to a mixture of asbestos and coke, or to certain other similar materials, which become incandescent and radiate the heat outwards. This prevents the heat passing by convection directly up the flue or chimney; the obnoxious products of combustion pass up the flue, but a fair percentage of the heat is diverted into the room. For cooking purposes coal-gas is extensively used. Special gas-ranges are now designed, by means of which hot gas-flames may be produced by more complete combustion of the gas than obtains with the ordinary gas-flame employed in illumination. The heat thus produced is localised in that region where it is most wanted, such as, for instance, immediately below a kettle or saucepan placed in position on the grate, and the boiling of water or other such culinary operation rapidly ensues. With regard to the special purpose just mentioned, that of the production of boiling water, various patents have been brought out, depending upon the local application of heat obtained from gas. Water may be rapidly heated by passing through thin metal tubes or over thin plates, the other side of which is subjected to the heat of the gas-flame. This is very useful for the preparation of warm baths and the like.

In engineering and various arts coal-gas and other similar products have been in extensive use for some years. In the gas-engine (q.v.) the combination of coal-gas with a suitable amount of air is made to produce an explosion in a cylinder, to cause a rapid increase in the temperature, and a consequent increase in pressure of the gaseous mixture; and the energy thus developed is directed so as to produce a reciprocating motion of a piston, and by suitable mechanism a rotatory motion of shafting and wheel-gearing. Special combustible gases, known as producer-gas, water-gas, and Dowson gas, are obtained by passing limited supplies of air or of air and steam through incandescent coke. This fuel is fairly cheap, and is much utilised for heating retorts in coal-gas making, in metallurgical operations, in glass and pottery works, boiler-heating, and in gas-engines. In various parts of the earth, such as Baku, China, and specially in North America, natural gas issues from the ground, and is employed similarly. Some varieties of this natural gas are useful for illumination.

There can be no doubt that the great advantage of smokeless burning is possessed by gas-fuel, though certain disadvantages also attend its use.