IMPROVEMENTS IN GAS PRODUCING FURNACES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Joshua Kidd at the Office of
the Commissioners of Patents, with his Petition, on the 17th
September 1874.
I, JOSHUA KIDD, of 24, Martin's Lane, in the City of London, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN GAS PRODUCING FURNACES," to be as follows:-
My Invention consists in making solid fuel into gaseous fuel by
exhausting the products of combustion from a fire and forcing the same
through red hot fuel by means of the escaping force of a jet of super-
heated steam or hydrocarbon vapor.
In carrying out my Invention I construct an open furnace and
surround it with fire brick; attached to this furnace is a raised hollow
stack or hopper opening at the bottom into the furnace, by means of
which the fuel is supplied, thus allowing it as it descends to get heated
before it reaches the hottest part of the furnace. To this furnace I
attach a closed brick decomposing chamber, or second furnace with
fire-bars placed about twelve inches from the bottom; about eighteen
inches above these fire-bars I place a second set of fire-bars shorter than

page_text: the lower layer, so that the fuel can be pushed off the upper bars down
on to the lower bars.
The fuel is supplied to the upper grate bars through a hopper with an
air-tight lid, and after it has parted with its gas it is either withdrawn
or raked on to the lower grate bars. A tubular orifice conveys the
products of combustion from the upper part of the first furnace into
and under the lower grate bars in the decomposing chamber._
An artificial draft is created by the escaping force of a jet of super-
heated steam or hydrocarbon vapor placed near the outlet of the tubular
orifice in the first fire-box; the products of combustion are forced
through the lower layer of fuel in the decomposing chamber and soon
raises the fuel to a white heat, when the carbonic acid gas and vapor
from the exhaust jet becomes decomposed into a combustible gas, which
in burning gives out great heat. The heat from the lower layer of fuel
distills off the gas from the upper layer and charges it with hydrocarbons
and better enables it to be used for lighting and heating purposes. From
this description it will be seen that the first furnace will give off mostly
incombustible gas; and the incandescent fuel on the second grate
decomposes this gas and renders it combustible by changing the carbonic
acid into carbonic oxide gas. The steam or hydrocarbon vapor used for
the forcing jet becomes also decomposed in passing through the incan-
descent fuel, and is changed into a combustible gas. The fuel on the
third grate parts with its gas and vapor enriching the gas from the
second grate with hydrocarbons.
Where steam is not supplied from a seperate boiler I prefer to
generate and superheat the steam by the waste heat from the decom-
posing chamber. In starting the furnace and before combustible gas
is generated, it is necessary to raise the temperature of the furnace and
the fuel in the decomposing chamber to a white heat; this I accomplish
by letting the fire burn in the ordinary way, and attaching for that
purpose a temporary chimney to carry away the products of com-
bustion. The gas generated, as before described, may be conveyed
through pipes like common retort gas, and may be used for lighting.or
heating purposes.

page_text: The furnace attached to the before-mentioned decomposing chamber
may be used seperately, if required, for generating steam or for any
other heating purposes. When so used I exhaust the gas generated
from the fuel in the upper part of the hopper or stack by means of the
escaping force of a jet of steam, and force it mixed with atmospheric
air through the incandescent fuel placed on the grate bars. By this
means powdered fuel may also be forced with the gas and vapor through
the burning fuel if required.