Improved Bakers' Oven.
Year: 1899

page_text: Date of Application, 2nd Feb., 1899
Complete Specification Left, 17th Nov., 1899-Accepted, 23rd Dec., 1899
[Communicated from abroad by LA SOCIÉTÉ INTERNATIONALE DE MEUNERIE ET DE
PANIFICATION, of Brussels, in the Kingdom of Belgium, Manufacturers.
Improved Bakers' Oven.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster, and
Lower Temple Street, Birmingham, in the County of Warwick, Civil Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to a novel system of baking-oven constructed with the
view of obtaining a regular and continuous baking of the bread under special con-
ditions and by aid of improved heating arrangements, which effect considerable
economy of fuel.
In this apparatus the baking takes place in retorts into which steam is intro-
duced, and which are furnished with tightly closing doors at their ends, so that
the steam introduced comes in contact with the loaves and envelopes them
with an atmosphere particularly suited for baking.
The loaves for baking are placed on trays of perforated sheet-iron which travel
on suitable rollers at the bottom of the said retorts, and these retorts are placed
in an inclined position so that when the tray at the lowest end of the retort is
taken out, there is an empty space ready for receiving another tray of loaves to be
baked at the opposite, the highest end.
The said retorts are grouped parallel in a brick oven in such a way as to form a
battery, the single retorts thereof being heated by means of gas fuel produced in
an ordinary gas producer.
A battery of retorts includes a gas producer, in which is produced heating
gas by partially burning any combustible. This combustible is introduced by an
opening arranged in such a manner as to prevent the air entering during the
charging.
A supplementary gas producer can be added to the battery to be used in case
the first should be stopped for repair, or for any other reason.
The oven proper includes a given number of cast-iron retorts arranged parallel
in a brick oven, and heated by burners supplied with the heating gas from the
gas producer.
The retorts may be furnished with a certain number of ribs and longitudinal
curves which are intended to regulate the transmission of the heat.
These retorts are further provided with flat door frames intended for the recep-
tion of refractory partitions, and have also two lateral grooves or channels in
which are placed the rollers on which the trays for the loaves to be baked travel.
The retorts are formed of a certain number of segments which fit perfectly
end to end. This arrangement has advantages from the point of view of casting
and of transport, and allows of the construction of retorts more or less long as
required, by means of a particular type of segment.
The lower portion of the retorts rests on a surface of refracting material,

page_text: which is intended to prevent direct contact of the hot gases with the wall of the
retort.
The surface of the trays on which the loaves for baking are placed, is formed of
a perforated sheet of iron, and the perforations of this sheet can be of any form
considered suitable.
The loaves taken out of the oven after baking on the sheet thus perforated,
have on their lower surface the exact reproduction of the perforations of the
sheet, and that in the form of a slight relief in a darker tint than the rest of the
loaf. There can thus be produced on the lower surface of a loaf all kinds of
designs or inscriptions, such as a trade-mark, by giving to the perforations of
the sheet of the tray, the shape of the reverse side of the design to be reproduced.
Or in the same manner loaves can be made bearing the date of the day on which
they were baked.
The steam tight doors which close the ends of each retort are provided with a
rim carefully set which slides and fits exactly against a plate which forms the end
of the retort, and in which a spy-hole is pierced for observing the baking. The
door is moreover guided in two lateral grooves in such a way that it can be run
vertically, and it can be worked easily by means of a pedal through the medium
of levers suitably jointed.
Each group or battery of retorts is completed by a steam producing apparatus
intended to maintain the desired degree of moisture in the retorts, and chiefly
composed of a boiler placed in the track of the gases escaping towards the chimney
in such a way as to utilize thus a certain quantity of heat which would other-
wise be lost.
The steam produced is distributed in the retorts by means of pipes which open
into perforated tubes in the retorts.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C.,
Patent Agents for the Applicant.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Solicitors, 322 High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster, and
Lower Temple Street, Birmingham, in the County of Warwick, Civil Engineer,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the follow-
ing statement:-
The present invention relates to a novel system of baker's oven constructed
with the view of obtaining a regular and continuous baking of the bread under
specially favourable conditions, and this by aid of improved heating devices
which effect considerable economy of fuel.
In this process the baking takes place in lengthened cast-iron chambers or
retorts having tightly closed doors at their ends so that the steam produced by
the evaporation of the moisture in the loaves remains in contact with these loaves
and envelopes them with an atmosphere especially suited for their regular baking.
These retorts are grouped parallel in batteries in a brick oven heated by means
of a gas producer, which will be described hereinafter in detail with reference to
the accompanying drawings.

page_text: In these drawings:
Figure 1 is a longitudinal section of the oven through the axis of one of the
retorts, showing the gas producer which heats a battery of retorts.
Figure 2 is a transverse section of the oven on three different planes, the right-
hand side of the figure being a section on the line X, X, the left hand side of the
figure being a section on the line X'X', and the central portion a section on the
line X2 X2, of Figure 1.
Figure 3 is a front elevation on a larger scale of the back of the oven, and the
door of one of the retorts.
Figure 4 is a sectional view of the back of a retort.
Figure 5 is a perspective view of a tray for the loaves.
As will be seen from the drawings, the oven consists of a given number of cast-
iron retorts N, the form of which has been designed so as to obtain a regular
transmission and distribution of heat, and which are placed parallel so as to be
heated together by means of the same gas producer P.
The gases produced in l' are introduced through the hole p controlled by the
valve p into a flue y and thence distributed through the valves q¹ to each of the
burners placed beneath the retorts N. These burners are constructed like those
usually employed for this particular kind of heating; that is to say they are
constructed with the apertures o for gas from the gas producer, in combination
with apertures o¹ supplying the air necessary for combustion. The shape and
position respectively of the said apertures can be varied as desired according to
the type of burner employed, or according to the composition of the gas furnished
by the gas producer.
The retorts used are preferably composed of a given number of segments n, n
which fit perfectly end to end. This arrangement has great advantages from
the point of view of their casting and transport and by using one particular type
of segment allows of the construction of retorts of any length be employing a
larger or smaller number of these segments. Moreover in case of accident, the
damaged part of the retort can be replaced without it being necessary to destroy
the whole oven;
if the retort were constructed in one piece the same amount of
repairs would entail much more work and considerable increase of expense.
The bottoms of these retorts rest on a surface of fire-proof brickwork n¹ this
arrangement being for the purpose of preventing the combustion gases coming
into direct contact with the wall of the retort during that part of their passage
when the gases are hottest.
Experience has shewn that if a portion of the retort were too strongly heated
the baking of the bread would be effected under circumstances prejudicial to its
quality.
The loaves to be baked are placed on rectangular trays V1 (Fig. 5) provided
with a frame which travels over rollers fixed laterally in the retort... These
trays descend by their own gravity by virtue of the slope from the upper to the
lower opening, so that when a tray is taken out at the lower end an empty space
is left near the upper opening ready to receive a fresh tray. The bottom of
these trays preferably consists of a sheet of perforated iron, permitting the free
access of hot air to the bottom of the loaves; any form considered suitable may
be given to the perforations of this sheet. Thus, loaves taken out of the oven
after baking, having travelled from one end of the retort to the other on the sheet
thus perforated, will reproduce exactly on their lower surface the perforations
of the sheet in slight relief and of a slightly darker hue than the rest of the loaf.
There can thus be produced on the under surface of the loaves any kind of design
or inscription such as a trade mark, by giving to the perforations of the sheet the
corresponding shape of the design it is desired to reproduce. Or in the same
manner loaves can be made bearing the date of the day on which they were
baked.
As mentioned above the retorts are provided at each end with steam-tight
doors for preventing all escape of heat or steam and placed as shewn on a larger

page_text: .scale in Figures 3 and 4. As will be seen from these figures, the cast iron
door S is provided with a carefully adjusted rim which slides and fits exactly
on a plate U which forms the end of the retort and which is correspondingly
adjusted. The door is further guided in two lateral grooves so that it can
slide vertically, and can be conveniently operated by means of a treadle sl
through the medium of levers s pivoted on supports w and guiding rods s. The
loaves are introduced into the oven in the following manner:
One of the perforated trays VI described above is placed on the table Z and
the pans containing the loaves to be baked emptied on to this tray; the treadle s¹
is then pressed in order to raise the door S and the tray pushed in so that it
moves on the rollers v.
At the other side of the battery of retorts this operation is reversed for taking
the trays out of the retorts when the loaves on these trays have been sufficiently
baked.
The plates at the end of the retorts are provided with an observation
hole through which the baking can be watched. This battery of retorts is
moreover completed by a steam producing apparatus for maintaining in the
retorts the desired degree of moisture. This apparatus is preferably composed
of a boiler R heated by the hot gases from the furnace escaping towards the
chimney, and provided with a safety-valve and a water level. The steam is
conducted by means of a pipe t discharging at the lower part of the retort.
Instead of injecting steam taken from the upper part of the boiler R into the
retort, hot water taken from the boiler R through a pipe t may be supplied
thereto. The water thus introduced vaporizes immediately for producing the
vapour required.
In order to be able to take the temperature of the retort, pyrometers k are
arranged in the front and back parts of the oven; the motion and frame of these
pyrometers are located in the observation hole u¹.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent I declare that what I claim is;-
1. An improved process for the continuous baking of bread, characterized
by, passing the loaves into a hermetically closed retort or metal chamber, heated
externally by means of heating gas from a gas producer; a plurality of said
retorts being preferably arranged in the same brick work erection and supplied
by the same gas-producer.
2. For carrying out the process characterized in Claim 1, the combination
of long cast-iron retorts, the bottoms thereof being protected by a layer of a
heat-resisting substance and closed at both ends by steam-tight metal doors,
substantially as described.
3. In a retort as characterized in Claims 1 and 2, a vertically sliding door
operated by means of a treadle s¹, levers s², and connecting rods 3 substantially
as described and illustrated in Figures 3 and 4 of the accompanying drawing.
4. In a baker's oven, the perforated trays V1 on which the loaves are placed
for passing them through the oven, the perforations of said trays being traced
with a design, trade-mark or the like for the purpose of reproducing said design
on the under surface of the loaves substantially as and for the purpose described.
5. The improved baker's oven constructed and operating substantially as
described in the specification and illustrated in the accompanying drawing.
Dated the 17th day of November 1899.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.