F[TRNACES, GAS. Classification.—The different kinds of furnaces for burning gaseous fuel are thus classified in a paper in the Proc, of the Inst. of Mech. Eng., January, 1891 : Gas-furnaces may properly be divided into four classes, namely: (a) with reversing regen eration ; (b) with continuous regeneration ; (c) non-regenerative; and (d) with blow-pipe or forced blast.
(a) Furnaces with reversing regeneration are of several different kinds ; 1. The ordinary Siemens furnace, in which both gas and air are heated before admission to the interior of the furnace, by being passed through the well-known arrangement of brick chambers filled with checker-work or loosely piled bricks.
2. The Batho or Hilton furnace, in which the regenerative chambers, instead of being partly or entirely underground, are incased in cylindrical wrought-iron vessels erected upon the ground-level.
3. Furnaces in which the air only is regenerated by being passed through chambers, the gas being admitted direct from the flues by which it arrives from the producers. In these furnaces the whole of the escaping gases or waste heat has to pars through one of the two air chambers on its way to the chimney.
4. The furnace recently described by Mr. Head (Iron and Steel Institute Journal, 1889), in which a portion of the waste heat is taken back to the gas-producer.
5. The various regenerative blast-furnace stoves of the Cowper, Whitwell, and other kinds.
(b) In furnaces with continuous regeneration, the air, before admission to the interior of the furnace, is heated in flues or pipes by radiation or conduction from the bottom of the fur nace, and through thin walls which separate she air-flues from the flues that carry the spent gases or waste heat to the chimney.
(c) In non-regenerative furnaces the air is admitted to the interior of the furnace at its natural or atmospheric temperature.
(d) Blow-pipe or forced-blast furnaces are of two kinds : First, those in which the air is supplied at its natural or atmospheric temperature by a fan or blower: second, those in which the air so supplied is heated by the spent gases or waste heat from the furnace, by being passed either through coils or stacks of pipes, or else through brick tubes or flues, as in the case of the Radcliffe furnace and others.
A New Siemens I?egeneratire Gas-Furnace.—Messrs. John Head and P. Pouff, in a paper
before the Iron and Steel Institute, read in 1889, describe a novel form of regenerative fur nice. We extract from their paper as follows: In the new Siemens furnace the gaseous products of combustion from the heating-chamber of the furnace are delivered under the grate of the producer. these gases consisting of intensely hot carbonic acid, water in the gaseous state, and nitrogen. The econonn• of fuel resulting from the conversion of carbonic acid into carbonic oxide is diagrammatically illustrated by means of the sketch (Fig. 1) of a gas-producer. Assuming that the producer contains only coke in the incandescent state, this coke, if fed with oxygen, will produce carbonic acid in the lower zone, which will he converted into carbonic oxide m the upper zone : but if fed with hot carbonic acid instead of oxygen, one half of the fuel, comprising the lower zone, ina?,' he dispensed with and an economy in weight of fuel to the same extent will be realized. In the new Siemens furnace the waste gases are directed partly through an air-regenerator and partly under the grate of the producer, there to be recon verted into combustible gases, and to do the work of dis tilling hydro-carbons from the coal ; in fact, the gas-pro duc•er in this case absorbs ot• utilizes the heat formerly deposited in the gas-regenerators of furnaces, mid in doing this transforms spent gases into combustible gases.
For the propulsion of the gases through the converter a steam-blast is employed. This steam is superheated by the waste gases from tho furnace, and, mixing with them, forms a very lint blast under the grate. The diagrams (Figs. 2 and 3) show the relation which exists between the ordinary and the new type of Siemens furnace. The func tion in both is the same. In the first case the waste gases are partly directed through two regenerators, while in the second case the waste gases are partly directed through an nir-regenerator and partly through a eon N•erter-prodncer. In both cases the waste heat from the furnace is entirely utilized, and the gas and air reach the furnace in an intensely heated condition. In both eases, again, there is a reversal in the direction of the Mame in the furnace, which insures uni form heating of the furnnee-ehatuher told the materials coot:lined in it.