Year: 1893

page_text: I, PAUL PFLEIDERER, of the Firm of Werner & Pfleiderer, of 117 Queen
Victoria Street, London EC., and of Caunstatt in Germany, Baking Engineer,
do hereby declare the nature of my said invention to be as follows:-
The object of iny invention is to effect improvements in the method of, and in
means and appliances for the transmission of caloric to ovens, whereby the.
temperature of the various parts may be controlled, regulated and localised to suit
And my invention
the requirements of the operations to be performed therein.
relates principally, but not exclusively, to externally fired ovens constructed and
worked on the "Perkins" and "Wieghorst" or on any of the flue systems.
In order to counteract the effect arising from a more or less unequally fired
furnace, and to equalize the quantity of heat transmitted by the tubes or flues
located in above or below the baking chamber or chambers, I arrange such tubes
so that a number of points of contact are secured, by crossing or close setting of
the same; the contacts thus obtained being utilised in transference of caloric from
pipe to pipe by direct or indirect conduction. For this purpose a number, (in
Perkins and Wieghorst ovens an additional number), of water and steam tubes
may be required; and such additional tubes may be located in the baking chamber
or its brickwork, either inclined or horizontally, with or without exposing any part
thereof to the furnace or flues; their function being that of a caloric storage
battery for the equalization of the temperature and radiation of heat in the baking
chamber.
I also form some or all of the pipes or tubes with a series of gills or annular
or other collars, for the purpose of increasing the heating surface of the pipes in
the furnace, and the conductivity of such parts of them as are located in the
baking chamber.
My invention also consists in fitting in the Perkins or Wieghorst furnaces,
pivoted deflector plates, so mounted and actuated that they may be set at suitable
angles, and thus caused to deflect or direct the fire gases or rays of radiated heat
in any required direction, and towards any particular row of pipes, localising and
regulating the heat, and carrying the caloric in varying degrees of intensity to
various parts of the oven, where required, and reducing the temperature of other
parts.
In ovens on the Perkins or Wieghorst systems, and also in ovens otherwise
constructed and heated, I sometimes fit between the sources of beat or the radiating
surfaces and the goods to be baked, extended sheets of wire netting or perforated
metal, or plates of spongy iron asbestos, fireclay or analogous material, which act
as heat equalizers or checks and to some extent also as caloric storage batteries, or
they may modify the nature of the heat radiated or thrown from the pipes or flnes
to the goods to be baked by such heat rays.
1000

page_text: COMPLETE SPECIFICATION.
Improvements in Ovens.
I, PAUL PFLEIDERER, of the Firm of Werner & Pfleiderer, of 117 Queen
Victoria Street, London E.C., and of Cannstatt in Germany, Baking Engineer,
do hereby declare the nature of my said invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement —
The object of my invention is to effect improvements in the method of, and in
means and appliances for the transınission of caloric to ovens or similar apparatus,
whereby the temperature of the various parts may be more effectually controlled,
regulated and localised than hitherto to suit the requirements of the operations to
be performed therein. My invention relates principally, but not exclusively, to
externally fired ovens constructed and worked on the "Perkins" and "Wieghorst "
systeins.
And in order that my said invention may be particularly described and ascer
tained, reference is hereby made to the accompanying drawings, in which similar
letters of reference indicate corresponding parts.
Figs. 1 and 2 illustrate a sectional elevation and plan of an oven with baking
chambers B and B¹, arranged side by side, and heated by "Perkins" pipes, St
and S2, from one furnace F. What I term "storage" pipes C are shown in close
contact with the former primary or fire pipes S1 S2, some of the secondary or
storage pipes C also touching each other. T is a heat-conducting or equalizing
metal block (shown in dotted lines) projecting into the baking chamber B.
N is an extended moderator-sheet or screen of wire netting or other suitable
fabric, interposed between the top row of fire pipes S2 and the bread or other
goods to be baked, such screen extending downwards to shield the bread from, or
moderate the radiation of the hot furnace wall, separating the baking chamber
from the furnace F.
Figs. 3 and 4, illustrate a cross-and a longitudinal-section of two similar
ovens, showing alternative arrangements of my heat-storage, or equalizing, or
secondary caloric battery-pipes C, in their contact with, and relative position to,
the primary or heat-conveying fire-pipes S¹ and S².
The secondary or heat diverting pipes C, are bent downwards, touching the hot
furnace wall, and they are moreover united into one bundle by a block T¹, which is
partly built into the furnace wall, their upper ends being in close contact with the
top row of primary or fire-pipes S².
Figs. 5 and 6 illustrate a method of using a series or (or what I term a) battery
of my storage-pipes C, serving as heat-equalizers between the two baking-chambers
of "two-deck" ovens. The two baking chambers are separated by a ceiling 20,
formed in the lower chamber. The storage pipes, C, fit into holes made in this
partition or ceiling 20, and are gathered at the bottom in a block T, which may
extend through the furnace wall into the fire.
Fig. 7 is a section on the line 21, 21, of Fig. 8. Fig. 8 is a plan, and Fig. 9 is
an elevation, partly in section, illustrating a quadruple Wieghorst oven built on my
improved plan. The lowest row or series of bundles of pipes Cº, are used as fire
bars, and the surplus available heat therefrom is directed through flues fo, blocks To,
and a series of vertical diverting or secondary pipes C, into block T, and from that
through the pipes S¹, which form the bottom row of primary pipes, to the upper
chambers B and B, whereby ample and equalising bottom heat for the upper
baking chambers is secured.
The pipes Co do not directly communicate with or project into any of the baking
chambers, their surplus heat is transferred through T, C, and T, to the bottom
row of primary pipes S¹, of the upper chambers B³ and B, whose primary or heat

page_text: importing or conveying pipes S1 and S2 are farther away from the fire than those
feeding the lower baking chambers B1 and B2.
Similar metal blocks To and T, connected by secondary pipes C, may be built
into the middle wall between chambers B₁ and B, instead of transferring the heat
from Co by means of flues fo, f, and f, as shewn in Figs. 7 and 9.
No top row of primary or fire-pipes are shown in the chambers B1 and B2, but
instead thereof they are fitted with storage-pipes C, having annular gills, rings, or
collars g and g¹, the latter being shrunk or welded on the tube, the former being
made in one body, loosely pushed over the pipe and secured by casting metal into
the space left. The gills in chamber B², on the right hand side, (Figs. 7 and 9)
nearest to the hot furnace wall, are put near the middle wall, so that the bulk of
the heat drawn by pipes C, from the furnace wall (into which their ends are built)
is given out at the opposite ends. In the upper chambers, B and B, storage
pipes, C, are laid across the fire-pipes S, in bundles connected by clips or metal
blocks T
The buffers, or moderator sheets, or wire netting N, are shown fixed in the
chamber B, and are made adjustable so as to be more or less near the top of the
bread, as required in chamber B3, the sheet in chamber B being bent down, so as
to form a buffer or shield against the vertical furnace wall also.
By using my system of secondary or storage, or diverting and equalising pipes,
I am able to construct my furnace with several independent grates or fires as shown on
plan in Fig. 8. These separate fires require less skilled or attentive stokers, because
the pipes C, serving as fire-bars, are not at the same time serving as the bottom
row of primary pipes to a baking chamber, as any difference or irregularity between
the separate fires would seriously affect the uniformity and regularity of the baking
process through inequality between the temperatures obtaining in the various
pipes.
The deflector-plates 01 and 02 are shown as illustrating three different modes of
application. Those marked O being manipulated from a lever q (Fig. 9) fixed on
a pivoted axle, on which the deflector turus. Its most incliued position is shown
by dotted lines in Fig. 7, in which the deflector leans against the ends of the
pipes St, forming the bottom row which serves the lower baking chambers. In the
other arrangement O¹, the deflector-plate rests on the pipes S1 of the upper chamber,
and is held in position by a rod m, which, when drawn out as far as it will go, allows
the deflector plate 01 to lean over towards the back wall of the furnace, and thereby
entirely to close the draught and stop the fire-gases from rising. 02 may consist of
a fire-tile resting on the top of the pipes S2 in the furnace. By a rod n to each of
these fire-tiles they can be caused to slide in and out, so as to cover more or less
of the passage left by the pipes, and regulate the fire-gases passing up from the
furnace on their way to the chimney. Similar tiles b may be arranged in the
openings usually closed by ordinary soot-doors k, and may be utilized for the same
purpose, while they at the same time prevent loss of heat through radiation from
the soot-doors, which are applied for purposes of cleaning pipes and flues; for
which operation the blocks b will of course have to be temporarily withdrawn.
On the drawings, rails Rare shown, and drawplates P, carrying loaves, to show
in what manner and relative position to the latter the moderator or buffer-sheets N
are placed. Practically the only difference between this and a "peel "-oven with
fixed sole, is that the letter is a fixture, which cannot be withdrawn from the oven-
chamber, and that as such fixed sole or baking-plate is charged and filled with its
bread, loaf by loaf, through the intervention of a "peel" worked by haud, an oven
door of smaller dimensions is used.
The plan Fig. 8, shows a section on the line 22-22 of Fig. 7. The heat
conducting Perkins pipe is shown separately in Fig. 10 with gills and g¹ mounted
upon it. Figs. 11 and 12 illustrate one of my travelling-web baking-plates, in
which the chains are connected by storage-pipes C, having pins or trunnions p,
which inre free to rotate in the links of the chains, which are propelled by chain-
wheels or stars a, mounted on an axle a², which is moved by a handle i. The

page_text: baking tins or pans o are loosely laid on the revolving pipes C, on which they are
wound in and out of the oven. An apron n forms a convenient incline, over and
from which the baking tins may be allowed to slide, without manual attention, but
they may, if preferred, be lifted off. The drawing shows only part of this web-
plate, which is a mere modification of that described in my Patent No. 19,506 of
29th November 1890.
I sometimes use spiral conducting pipes surrounding the main or auxiliary heating
pipes, as shown in Figs. 13, 14 and 15.
I counteract the effects arising from a more or less unequally fired furnace, and
equalise the quantity and temperature of heat, transmitted by the tubes S, or by
the flues located in and around the baking chamber or drying closet, or similar
apparatus. For this purpose I arrange such tubes so that a number of points of
contact are secured between them by crossing or close setting of the same, the
contacts thus obtained being utilized in transferring and exchanging heat from
pipe to pipe by direct or indirect conduction, and I employ a number (in
"Perkins" and " Wieghorst" ovens an additional number) of hot water or steam
tubes C. Such additional tubes may be located in the baking chamber itself or
in the surrounding brickwork, and they may be set inclined or horizontally, with or
without exposing any part thereof to the direct action of the fire or furnace gases
in the flues; the function of these pipes being at the same time that of a calorie-
storage battery for the storage up of heat that may subsequently be required for
equalising the temperature and radiation of heat in the baking chamber or drying
closet.
I perform this part of the invention and put it into practical use in the following
manner: To prevent unequal flow of heat from the fire to the baking chamber or oven
proper with an unequally fired "Perkins" or "Wieghorst furnace, I connect
those pipes which are nearer to the more intense fire, by heavy metal blocks T,
with those likely to be exposed to the less intense fire, both series of pipes fitting
exactly into the block so as to form with it as nearly as possible one solid whole,
such block being built into the firebrick wall separating the furnace from the
baking chamber into which the blocks may project, thereby the block tends to
conduct any surplus heat from the hotter parts of this fire-wall to the cooler parts
of the baking chamber, through the equalising medium of the bundle of pipes S',
with which it is in close contact, and when I want to increase the effect, and to
form a sort of heat storage battery, I put one or inore additional pipe or
pipes, or series, or rows, or bundles of such pipes C, entirely into the baking
chamber itself, sometimes across, sometimes parallel with the heating pipes S,
and sometimes diagonally to them, either loosely or in a fixed connec-
tion made with the latter, by connecting clips similar to those described
in my Patent No. 1265501, and illustrated on Sheet 1, or by bars or blocks T,
similar to the first above mentioned metal blocks. I also build such heat
storage pipes C. with their ends into the furnace wall, always taking care that the
largest number of pipes have one end nearest to the hottest part of the furnace, and
their other ends nearest those points in the baking chamber which are exposed to
the largest amount of cooling influence, even if this should necessitate bending the
pipes, whenever the greatest stability and uniformity of heat is desired. In
case of flue ovens, whether externally or internally fired, I follow this rule and
connect the hottest parts of the interior of the baking chamber, or of its walls, with
those parts most liable to get cooled in the process of baking or manipulating, by
means of a series of Perkins pipes, the fluid in which is constantly circulating, and
actively engaged in equalising any difference in temperatures, which may arise in
the atmosphere surrounding their ends or intermediate parts. In internally fired
ovens these auxiliary pipes C, if employed, should be located in, or protected by, the
brickwork, so that a very small part only of their surfaces, or no part thereof,
should be exposed to the fierceness of the fire, while it burns inside the baking
chamber. In a so-called side flue oven, for instance, I form the fire bars of Perkins
pipes, which I build into the brickwork of the oven, in such a manner that, on the

page_text: fire or heat receiving end, the amount of heating surface situated in or under the
fire proper, is proportionate to the amount of heat-radiating surface left at the other
end of each pipe, which other end I endeavour to place in that part of the oven
which ordinarily is the coolest. One result of this is, that I thereby considerably
reduce the loss of time required for the oven to "rest," and get "solid," after firing.
Hitherto these "Perkins "pipes have only been used set at an incline with the lower
end in the fire or furnace. No part of the pipes C, requiring to be in the furnace F,
or in the original source of heat, I wish it to be understood that my invention
does not deal with the initial system, or principle, or actual mode of conveying the
heat from the fire to the baking or drying chamber B, or other place where it is
required; but my invention only deals with the transportation or dislocation, or
redirection or redistribution, from one particular corner or spot of the baking
chamber to another, of an already (somehow) conveyed or introduced quantity of
heat. And it further deals with the interception or storage of this heat, in its
passage, or at its arrival at the end of the tubes S, in a manner which keeps the
heat always ready to move automatically, when it is required, towards that place or
spot on the baking plate or chamber where it is most needed. Where, by reason
of the particular design or construction of the apparatus, a sluggish, or no circulation
and mixing of the heated air obtains, as is the case with the baking chambers B
and B₁ of most systems of ovens built on the so-called Decker plan, while it would
nevertheless be desirable that the upper oven B₁ should have the same baking
temperature as the lower B, (Figs. 5 and 6) a sufficient number of heat conducting
pipes C, having one end in the upper, and the other end in the lower oven, will the
more quickly equalise the temperature of the two ovens; the larger a number of
pipes C, or the amount of superficial pipe area are exposed. The oven illustrated
on Sheet 3 of my Patent No. 12655, has its baking chamber divided, by a
horizontal partition, into an upper and a lower compartment, but has only one
furnace. A series of Perkius pipes passing from one compartment, through the
partition, into the other compartment, will effectually equalize the heat in the two
compartments, whether it be the upper or the lower compartiment which may have
a tendency of becoming hotter, while by air circulation this would only arise in case
the lower compartment were the hotter one and then only very slowly.
If the left hand chamber of a double oven, with the two chambers or compart-
ments side by side, separated by a wall, through which heating pipes common to
both are passing were found hotter than the right hand chamber, no natural
circulation could equalise the heat in both chambers but my system of storage or
redistribution pipes C, can cure such fault.
I also forin some or all of the pipes or tubes with a series of gills or annular or
other collars for the purpose of increasing the surface of the pipes, and the
radiating power of such parts of them as are located in the baking chamber,
evensole or drawplate. This I carry out by either forging, or welding, or brazing
on the gills or collars gl so as to form one solid body with the pipe, or I make them
separate, a number of them forming a sleeve or collar g which is shrunk on the
pipe; or, leaving a space or coring, I only push it over the pipe loosely, and fix it
by casting metal into the coring or annular space left between; or I form the
increased surface, by coiling or twisting the pipe in corkscrew fashion; or, in case
of storage pipes C, in Weighorst ovens,-by constructing the drawplate frame or
carriage, or the rails, of such storage pipes C, as bearers or connecting pipes, or
similar structural elements.
By fitting in the Perkins or Weighorst furnaces the pivoted deflector plates, so
mounted that they may be set at suitable angles, and caused to deflect or direct
the fire gases, or rays of radiated heat, in any required direction, and towards any
particular row of pipes, localising and regulating the heat, and carrying the caloric,
in varying degrees of intensity, to various parts of the furnace or baking chamber,
I also effect an increase of heat in some, and reduce the temperature in other
parts. This object I carry out by means of the metal plates or firetiles O,
supported on axles or hinges. or on recesses or projections in the furnace masonry,

page_text: and by leaning such metal plates or fire-tiles against some pipe or pipes, or against
the pipe blocks, in such a manner that such plates or fire-tiles O may each be
actuated outside, through a small opening in the back, top, or side of the furnace
wall of the oven, so as to be made to assume the desired position or angle of
inclination towards the pipes.
In the ovens on the Perkins or Wieghorst systems, and also in ovens otherwise
constructed and heated, I sometimes introduce between the sources of heat, or the
radiating surfaces, and the goods to be baked, extended sheets N, formed of wire
netting, or perforated metal, or plates of spongy iron, asbestos, fireclay, or analogous
material, which act as heat equalizers or interceptors, or checks, and, to some
extent, also as calorie storage batteries; or they may modify the nature of the
heat radiated or thrown from the pipes or flues, or walls, to the goods to be baked
by such heat rays. These heat buffers, or filters, or protecting shields or guards,
I hang up or I support them from the roof or sides of the baking chamber, by any
known contrivance, either as fixtures, or so as to be easily adjustable at a more or
less distance from the goods.
1
"
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 what
claim is-
1. İn
ovens or similar apparatus of the description and character herein before
described, the improved method of combining in the capacity of secondary or heat-
storage batteries a number of ordinary (so-called) "Perkins" high pressure hot
water or steam heating pipes, or other heat conducting tubes C, charged with
heat-conveying fluid, and having their ends welded up, or otherwise hermetically
sealed.
(a.) For the purpose of regulating and re-directing or diverting and equalizing
the flow of heat which is being conducted or transmitted by primary
heat-conducting pipes or by flues, or brickwalls, from the fire and furnace
or other source of heat, or for intercepting and storing such conducted
heat, and
(b.) For controlling regulating and localizing the radiation and the
temperatures obtaining at different periods of time in the various parts of
the baking, drying, or other heating or cooling chamber, closets or rooms,
irrespectively of the original or primary source of heat, or of the particular
means of its importation into these chambers as described.
2. The combination or arrangement in baking-ovens as aforesaid, of Perkins pipes
fitted with gills or collars g, for increasing the heating or radiating surfaces,
substantially as herein before described and illustrated by the drawings.
3. The combination in "Perkins" and "Wieghorst" oven furnaces, of deflector
plates or tiles (), substantially as hereinbefore described and illustrated by the
drawings.
4. The combination with and use in "Perkins" and " Wieghorst," ovens, of
buffer or moderator sheets N, of wire netting or other suitable material, substan-
tially as and for the purposes hereinbefore described and illustrated by the
drawings.
5. The improvements in ovens, substantially as and for the purposes described.