Improvements in Furnaces.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Furnaces.
FRANZ PAUL of Lübben, Germany, Machinist, do hereby declare the nature of this
invention to be as follows:-
By means of the fire-box which is the object of the present invention the production
of smoke will be kept within the smallest possible limits, and the caloric force of the
combustible will be notably increased by the fact that the air intended for combustion
is previously heated, and thus the necessary condition is afforded for the most perfect
combustion obtainable.
The heating of the combustion air is effected by passing it through a special fire-box,
placed in the channel through which the combustion air arrives.
With the fire-box in question, it is assumed that the access of the combustion air
to the combustible is effected by way of the door of the fire-box. This door is so
arranged that it forms, itself, a fire-box. It is composed of a hollow case completely
shutting off the channel leading to the fire-box, so that the air can only enter through
the openings provided in the door. For this purpose the lower face of the door is
formed as a grating whilst the bottom partition, here serving as a fire-bridge, is
furnished with suitable openings. In the upper part of the fire-box door there is a
swinging door held by a turn-button and through which the combustible is thrown
on to the grating. The latter is constructed to move on hinges in order to facilitate
the cleaning and is held in a horizontal position by a screw. On the front wall of
the fire-box door is secured a handle. Under the grating there is an open box
serving as a cinder-box.
The effect of having such a fire-box door, itself a fire-box, is as follows:-
After the door has been loaded with fuel (a combustible such as coke, burning
without smoke is to be preferred) and the latter has been lighted, the fire in the
principal fire-box can also be lighted. The door being then shut, the combustion air
penetrates into the fire-box through the grating, the interior of the fire-box and the
openings of the rear wall of the latter. On its way, the combustion air is heated by
contact with the fuel in a state of ignition in the door of the fire-box and by mixing
with the combustion gases escaping from the latter, so that a too pronounced cooling
in the principal fire-box is avoided and the completest possible combustion is effected.
In order to avoid opening the fire-box door every time, for feeding the principal
grate, the following modification may be employed. The stoking door is composed
in its upper part of two distinct leaves closed by means of a hisp. If, in order to
feed the principal grate, one of these door-leaves is opened, only a very little cold air
will have direct access to the principal fire-box. In this case there is no need of
raising the back wall of the fire-box, more than to the height of the lower part of the
front wall. Otherwise the bottom wall may be divided in the same way as the front
wall and the two upper parts are then to be united with the parts of the front wall, so
that they may open at the same time as the latter.
In order to avoid too strong a radiation of the heat that comes out of the fire-box
door, towards the front, it is advisable to furnish the walls of the fire-box door, at the
part that projects in front, with some materials which are bad conductors of heat.
Dated this 20th day of July 1896.
L. DUVINAGE,
Agent for Applicant.

page_text: Improvements in Furnaces.
1, FRANZ PAUL of Lübben, Germany, Machinist, do hereby declare the nature of
this invention, and in what manner the same is to be performed to be particularly
described in and by the following statement :-
By means of the fire-box which is the object of the present invention the production
of smoke will be kept within the smallest possible limits, and the caloric force of the
combustible will be notably increased by the fact that the air intended for combustion
is previously heated, and thus the necessary condition is afforded for the most perfect
combustion obtainable.
The heating of the combustion air is effected by passing it through a special fire-box,
placed in the channel through which the combustion air arrives.
In the accompanying drawing which illustrates my invention.
Fig. 1 gives a vertical section through the fire-box door, placed there for the heating
of the combustion air.
Fig. 2 is a section through Fig. 1 on the line a―x.
Fig. 3 is a front elevation of the fire-box door.
Fig. 4 is a different front elevation of the same door.
With the fire-box in question, it is assumed that the access of the combustion air
to the combustible is effected by way of the door of the fire-box. This door is so
arranged that it forms, itself a fire-box. It is composed of a hollow case completely
shutting off the channel leading to the fire-box, so that the air can only enter
through the openings provided in the door. For this purpose the lower face of the
door is formed as a grating r whilst the bottom partition h, here serving as a
fire-bridge, is furnished with suitable openings s. In the upper part of the fire-box
door there is a swinging door k held by a trap s' and through which the combustible
is thrown on to the grating r. The latter is constructed to move on hinges in order
to facilitate the cleaning and is held in a horizontal position by a screws. On the
front wall of the fire-box door is secured a handle b. Under the grating there is
an open box a serving as a cinder-box..
The effect of having such a fire-box door, itself a fire-box, is as follows:-
After the door has been loaded with fuel (a combustible such as coke, burning
without smoke is to be preferred) and the latter has been lighted, the fire in the
principal fire-box can also be lighted. The door being then shut, the combustion
air penetrates into the fire-box through the grating the interior of the fire-box
and the openings s of the rear wall of the latter. On its way, the combustion air
is heated by contact with the fuel in a state of ignition in the door of the fire box
and by mixing with the combustion gases escaping from the latter, so that a too
pronounced cooling in the principal fire-box is avoided and the completest possible
combustion is effected.
In order to avoid opening, the fire-box door, every time, for feeding the principal
grate, the following modification shewn in Fig. 4 may be employed. The door vis
composed in its upper part of two distinct leaves closed by means of a hasp e.
If in
order to feed the principal grate, one of these door-leaves is opened, only a very
little cold air will have direct access to the principal fire-box. In this case there is
no need of raising the back wall h of the fire-box, more than to the height of the
part of the front wall. Otherwise the bottom wall h may be divided in the same
way as the front wall and the two upper parts are then to be united with the
parts c&d of the front wall, so that they may open at the same timo as the latter.
In order to avoid too strong a radiation of the heat that comes out the fire-box
door, towards the front it is advisable to furnish the walls of the fire-box door, at

page_text: the part that projects in front, with some materials f which are bad condictors
of heat.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that whit I
claim is :
A fire-box with a device for the previous heating of the air for combustion,
distinguished by its door containing a special interposed fire-box or case, wich
the air for combustion is forced to pass through and where it becomes heated,
substantially as described and for the purpose specified.
Dated thi Lib dow of Ancil 1907
L. DUVINAGE,
Agent for Applicant.