IMPROVEMENTS IN AND RELATING TO FURNACES FOR THE MORE PERFECT COMBUSTION OF FUEL THEREIN
Year: 1881

page_text: LETTERS PATENT to William Phillips Thompson, of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, in the County of Lancaster, and
of 323, High Holborn, in the County of Middlesex, Civil Engineer, for an
Invention of "IMPROVEMENTS IN AND RELATING TO FURNACES FOR THE
MORE PERFECT COMBUSTION OF FUEL THEREIN." A communication from
abroad from Monsieur Emile Achille Prevost, of Paris, in the Republic of
France.
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson
at the Office of the Commissioners of Patents on the 1st November 1881.
WILLIAM PHILLIPS THOMPSON, of the Agency for Foreign Patent Solicitors,
6, Lord Street, Liverpool, in the County of Lancaster, and of 323, High Holborn,
in the County of Middlesex, Civil Engineer. "IMPROVEMENTS IN AND RELATING
TO FURNACES FOR THE MORE PERFECT COMBUSTION OF FUEL THEREIN." A com-
munication from abroad from Monsieur Emile Achille Prevost, of Paris, in the
Republic of France.
The present application for a Patent has for its object to secure to me the
exclusive right to a system of furnace in which air is injected above the bars,
having for its object to remedy the inconveniences of industrial furnaces actually
in use and permitting greater economy in fuel, and also of the employment of fuel
now rejected as too poor or as impossible to burn.
The present system of heating in boiler or other furnaces presents three principal
inconveniences:-First, the damper being regulated at the free will of the stoker
there is almost always an excessive draught, and consequently an excess of cold
air introduced into the furnace, and gases are drawn off before they can take fire;
second, useless distillation of fuel during the first few tuinutes following charging,
the bars (and consequently the free entrance of air) being then in part obstructed;
third, loss of heat before charging resulting from the too free passage of air
through the openings between the bars then unobstructed. There is an almost
continual escape through the bars of a considerable proportion of cinders. Further,
the necessity of always maintaining a free passage of air through the bars obliges
Al...מ

page_text: the stoker to frequently clean them, which operation every time entails a great
loss of heat. In the aggregate all these losses amount to twenty five or thirty per
cent. and sometimes more.
This system, designed to remedy the inconveniences mentioned above, presents
the following distinctive characters-First. Disuse of the chimney as an aspirator
of air, and keeping it merely for the expulsion of the useless products of combustion,
the opening of the damper is reduced to a minimum. Second. Reduction of the
quantity of air introduced to the necessary minimum, and introduction of air no
longer below but above the bars by means of tubes supplied by suitable blowing
apparatus, and placed at the front and back of the furnace, and if necessary on the
sides also at about half the height of the bed of coal. Third. Closing of the ash-pit
by means of a door fastened hermetically and joined on to the ordinary water
tank. Fourth. Employment of broad bars slightly separated, the proportion of
spaces to bars being about that of one to five, the spaces only serving for lighting
and for the removal of ashes.
The most smoky coal burnt under these conditions only gives off a reddish and
inoffensive smoke, because all the gases ignite in the furnace and in burning
consume the particles of carbon which they hold in suspension. The economy in
fuel or the gain of steam appears to be at least thirty per cent.
It is easy to see that these improvements are applicable at small expense to all
new industrial furnaces or those already existing, although it is designed specially
-for-boiler furnaces. It is suitable for all flaming coals, and the advantage obtained
is as much greater as the coal is richer in gas. It is also to be understood that
the several parts of the improvements can be arranged in the most suitable
manner.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Phillips Thompson in the Great Seal Patent Office on the
1st May 1882.
WILLIAM PHILLIPS THOMPSON, of the Agency for Foreign Patent Solicitors,
6, Lord Street, Liverpool, in the County of Lancaster, and of 323, High Holborn,
in the County of Middlesex, Civil Engineer. "IMPROVEMENTS IN AND RELATING
TO FURNACES FOR THE MORE PERFECT COMBUSTION OF FUEL THEREIN." A coin-
munication from abroad from Monsieur Emile Achille Provost, of Paris, in the
Republic of France.
This Invention consists in a system of furnace in which air is injected above
the bars, having for its object to remedy the inconveniences of industrial furnaces
actually in use and permitting of greater economy in fuel, and also of the
employment of fuel now rejected as too poor or as impossible to burn.
The present system of heating in boiler or other furnaces presents three principal
inconveniences: First, the damper being regulated at the free will of the stoker
there is almost always an excessive draught, and consequently an excess of cold air
introduced into the furnace, and gases are drawn off before they can take fire ;
second, useless distillation of fuel during the first few minutes following charging,
the bars (and consequently the free entrance of air) being then in part obstructed;
third, loss of heat before charging, resulting from the too free passage of air
through the openings between the bars then unobstructed; fourth, an almost
continual escape through the bars of a considerable proportion of cinders. Further,
the necessity of always maintaining a free passage of air through the bars obliges
the stoker to frequently clean them, which operation every time entails a great
loss of heat. In the aggregate all these losses amount to twenty five or thirty per
cent, and sometimes more.
This system, designed to remedy the inconveniences mentioned above, presents
the following distinctive characters.
First. Disuse of the chimney as an aspirator of air, and keeping it merely for
the expulsion of the useless products of combustion, the opening of the damper is
reduced to a minimum.
Second. Reduction of the quantity of air introduced to the necessary minimum
and introduction of air no longer below but above the bars by means of tubes
supplied by suitable blowing apparatus, and placed at the front and back of the
furnace and if necessary on the sides also at about half the height of the bed of
coal.
Third. Closing of the ash-pit by means of a door fastened hermetically on the
ordinary water tank.
Fourth. Employment of broad bars slightly separated, the proportion of spaces to
bars being about that of one to five, the spaces only serving for lighting and for
the removal of ashes.
The most smoky coal burnt under these conditions only gives off a reddish and
inoffensive smoke, because all the gases ignite in the furnace and in burning
consume the particles of carbon which they hold in suspension. The economy in
fuel or the gain in steam appears to be at least thirty per cent.
It is easy to see that these improvements are applicable at small expense to all
new industrial furnaces or those already existing, although it is designed more
especially for boiler furnaces. It is suitable for all flaming coals, and the
advantage obtained is as much greater as the coal is richer in gas. It is also to be
understood that the several parts of the apparatus can be arranged in the most
suitable manner.

page_text: Examples of the kinds of construction most to be preferred are however
represented in the accompanying Drawings. Fig. 1 is a sectional elevation of the
first variety of the system; Fig. 2, sections on lines A, B, and C, D, of Fig. 1 ; and
Fig. 3, sections on lines G, F, and E, F, of Fig. 1; Fig. 4 is a longitudinal vertical
section of the second variety. In these a is the furnace; b, fire bars; c, bridge;
, ash-pit; e, door closing the ash-pit; f, blow holes for the air with or without
contracted nozzles (" busillons"); g, tubes for supplying the air, of cast or wrought
iron; h, pipes conveying the air from the blowing apparatus; i, i, cast-iron guard
plates, having apertures in line with the blow-holes in order to allow the air to
pass; j, space left between the bars and the air supply tubes, in order to allow
the ashes to fall out when cleaning the bars; k, furnace door having a saddle-back
in the arrangement shown in Fig. 4, so as to be able to regulate the depth of charge
more easily.
Having now described the Invention as communicated to me by my French
correspondent, I claim under the Letters Patent the manufacture of furnaces with
air injection above the grate, substantially as described in the foregoing Specifi-
cation, and more especially the following points
First. The employment in a furnace with closed ash-pit of pipes or nozzles,
arranged in the front and back and if desired along the sides also, blowing jets
of air into the furnace above the the bars at about half the height of the bed of
fuel, substantially as and for the purposes described and as shown in the accom-
panying Drawings.
-Second. In combination with the items set forth in the immediately preceding
claim, broad bars with narrow spaces between them, the damper in the chimney
being also only a very little opened.
Third. The arrangements and special constructions, represented by way of an
example in the Drawings, or any mere modification of the same in form, dimension,
or material of the different parts constituting the improved furnace herein
described.
In witness whereof, I, the said William Phillips Thompson, have hereunto set
my hand and scal, this Twenty eighth day of April, in the year of our
Lord One thousand eight hundred and eighty two.