Improvements in Counter-current Air Heaters for Gas Fired Furnaces.
Year: 1894

page_text: Date of Application, 7th Mar., 1894
Complete Specification Left, 5th Jan., 1895-Accepted, 16th Mar., 1895
PROVISIONAL SPECIFICATION.
Communicated from abroad by AUGUST KLÖNNE, of Dortmund, Germany,
Engineer.]
Improvements in Counter-current Air Heaters for Gas Fired
Furnaces.
I, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Iust. P.A.,
F.I. Inst., practising as Phillips and Leigh at No. 22 Southampton Buildings,
Chancery Lane, London, W.C., Engineer and Chartered Patent Agent, do hereby
declare the nature of this invention to be as follows:-
It is of importance to work gas fired furnaces with as weak a draught as possible
in the air heating chambers in order that the process of combustion may not be
injuriously affected by the inevitable flaws in the party walls of the various flues
which flaws may be due to the porosity of the stone or to the settling and shrinking
of the masonry.
In order to minimise the draught, in point of strength as much as possible, it
is necessary to give the gas and air flues as large a cross section as may be
practicable.
The present invention attains the same object in counter-current air heaters by
dividing the flues both for air and gas into several independent chambers or groups
of flues or channels.
In the accompanying drawing Figures 1, 2, 3 and 4 show such an arrangement
of a counter-current air heater. The secondary or upper air enters the channels a
and b and takes the course indicated by arrows in Figure 2. The air entering at a
traverses the channels a', a", a¹II and enters the collector e at a Figures 2 and 3.
The air entering at b traverses 1, 6, whence it reaches the collector. The gas
current is also divided up into two courses, one of which runs through the
channels d, d, and the other through d, d¹. The channels d³, dare connected
with the chimney. The primary or under-air-current enters at c and passes to c¹
where it mixes with the steam produced in the basin W with which it passes
under the grate of the generator.
In Figure 5, the division of the upper air-currents is further shown. Here the
air enters in four currents at a, b, c, d and takes the course indicated by arrows
in Figures 8, 9 and 12. The junction of these four air-currents is effected in the.
channel e. The separated inflammable gases pass through the channels f and
effect a junction in the channel g. This channel is closed in towards the top by
a water reservoir W which forms the sole-plate of the under-air flue h. The flue h
is also heated from above through the crown of the regenerator.
Figures 1, 7, 10 and 11 show a simplification of the construction illustrated in
Figure 5. The upper air currents enter here at a and b and traverse in the
direction of the arrows, the channels shown in Figures 7 and 10, and effect a
junction in the channel e. The direction of the inflammable gases is also the same
as above described, and a similar arrangement applies to the under air currents
channels and the water reservoir.
Thanks to the above described arrangement of the air flues, the process of
combustion can be regulated in the furnace. According as to whether certain
interchangeable dampers-Figure 13-are moved so as to admit more or less air

page_text: into the channels, so will the combustion be more or less intense. Hence the
possibility is offered of heating the front, back, or middle of the stove to a greater
or lesser extent as may be desired.
Further, by the introduction of divided air currents, a more perfect combustion
of the heating gases is effected and hence a greater saving of fuel is attained.
Dated this 7th day of March 1894.
Improvements in Counter-current Air Heaters for Gas Fired
Furnaces.
I, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
F.I.. Inst., practising as Phillips and Leigh, at No. 22 Southampton Buildings,
Chancery Lane, London, W.C., Engineer and Chartered Patent Agent, 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 following
statement:-
It is of importance to work gas fired furnaces with as weak a draught as possible
in the air heating chambers in order that the process of combustion may not be
injuriously affected by the inevitable flaws in the party walls of the various flues,
which flaws may be due to the porosity of the stone or to the settling and shrinking
of the masonry.
In order to minimise the draught, in point of strength, as much as possible, it
is necessary to give the gas and air flues as large a cross section as may be
practicable.
The present invention attains the same object in counter-current air heaters by
dividing the flues both for air and gas into several independent chambers or groups
of flues or channels.
Figures 1 to 6 refer to the first form of construction; Figures 7 to 10, to
the second form of construction; and Figures 12 to 14 to the third form of
construction.
Figure 1 is a vertical, longitudinal section along the line 1-1 of the Figure 5.
Figure 2 is a similar section along the line 2-2 of Figure 5.
Figure 3 is a vertical longitudinal section along the line 3-3 of Figure 5.
Figure 4 is a similar section along the line 4-4 of Figure 5.
Figure 5 is a vertical transverse section along the line 5-5 of Figure 3.
Figure 6 is a horizontal section through the air heater along the line 6--6 of
Figure 3.
Figure 7 is a vertical longitudinal section along the line 7-7 of Figure 9.
Figure 8 is a vertical longitudinal section along the line 8-8 of Figure 9.
Figure 9 is a vertical transverse section through the air heater along the
line 9-9 of Figure 7.
Figure 10 is a horizontal section along the lines 10-10 of Figures 7 and 8.
Figure 11 is a vertical, longitudinal section along the line 11-11 of Figure 12.
Figure 12 is a vertical transverse section along the line 12-12 of Figure 11.
Figure 13 is a vertical transverse section along the line 13-13 of Figure 11.
Figure 14 is a horizontal section along the line 14-14 of Figure 11.
Figure 15 is a vertical section along the line 15-15 of Figure 16, and
Figure 16, a front elevation of an air regulating slide.
In Figures 2 and 4, the flues marked, d¹ and d², are those through which the
hot gases which serve to heat the air heater, are led in the direction of the arrows.
These gases, which may be conducted directly into the chimney, after they have
passed through the flue d, give their heat to the vertical walls, shown in Figures 5

page_text: an. 6, which they touch and which also serve as the side walls of those flues
through which the air which is to be heated, is conducted.
These latter flues are represented in vertical transverse section in Figures 1
and 3. Those which are meant to heat the air which is to be conducted under the
firegrate of the respective oven furnace are marked c and c¹ this air is hereinafter
referred to as the bottom air.
The air passes through the flues c and d in the directions indicated by the
respective arrows in Figure 1.
Those flues which are to heat the air which is to be conducted above the
firegrate into the furnace are marked in Figure 3 by the references a', a³, a³, b, b¹
and b².
In passing through such flues the air takes the direction shown by the arrows.
It is hereinafter referred to as the top air.
As the Figures 5 and 6 plainly show, the air flues a to a³ and to lie between
the hot gas flues d to d², while the flues c, c' for the bottom air, lie to the left, by
the side of one of the said flues.
The air which has been heated in the flues, a to a³, and b to 62, is conducted by
two flues at and 3, (compare Figures 2, 3, 5 and 6) into a collecting flue e which is
also heated by one of the hot gas flues d, and from which it is readily conducted at
both ends to the furnace by two flues e¹.
As shown by Figures 5 and 6, the flues at and 63 intersect one of the flues d.
A pan W may be fixed in the lower flue c¹ for the bottom air, to supply to the
latter a small quantity of steam.
The modified construction of the air heater which is shown in Figures 7 to 10,
is distinguished from the one just described, by the fact that the hot gases, are not
conducted several times backwards and forwards as, for instance, in Figures 2
and 4, but pass in a single, narrow and high flue along the top air flues which
latter bear the same reference letters in Figures 7 and 9 as in the preceding
figures. Moreover instead of one system of heating flues for the top air, two have
been arranged, as Figure 9 plaiuly shows.
In this modified construction, therefore, the one hot gas flue lies between the
two systems of air flues, while the second hot gas flue lies to the right at the side
of the right air flue a to a³ and to 62. The collecting flue e has been removed;
the two upper flues 62, 62, and a³, a³, are each connected by a flue ³, a, and at
the place where the two flues & and as in Figure 9 meet, that is at the middle
of the air heater, the flue e¹ for the escaping air branches off from the air heater.
The flue el forms, therefore, the straight continuation of the two short cross flues ³
and a¹.
The water pan W does not extend in this modified construction of the air
heater, over the whole length of it, but provides for the passage of two vertical
flues (Figures 8, 9 and 10) which conduct the hot gases under the pan W and
from there through the flue R into the chimney. The bottom air is conducted over
the water pan which extends over the whole width of the air heater and escapes
through two Hues e² from it.
As shewn in Figure 10, the air flues are very effectively heated by the
escaping hot gases.
Figures 11 to 14 represent a further modification in which the flues for the hot
gases and the bottom air are constructed exactly in the same way as in the modified
construction just described. The flues for heating the top air are constructed
even in a simpler way having only three single flues a, a' and a², as shewn in
Figure 11.
As plainly shown in Figures 12 to 14, here also two systems of air flues a to a³
have been arranged. The one hot air flue d lies between them.
The two upper flues a² are connected by a cross flue a', in the straight continuation
of which the exhaust flue e¹ is joined to the air heater.
If the exhaust for every single system of the top air flues are fixed separately
(as is shown, for instance, in Figures 1 and 6)-and to do so would necessitate the

page_text: lividing in two halves, of the flue e by the prolongation of the middle wall,
(indicated by dotted lines in Figures 1 and 6)-the respective furnace can be
supplied at the different places where the flues el run into it, with air of different
temperatures, or with different quantities of air, which would to a certain degree
influence the process of combustion. To obtain air, heated to different degrees, or
to heat different quantities of air, it is necessary to fix air regulating slides or
lampers. The best place for fixing them is the junction of the air flues a and h.
Referring to Figures 15 and 16, a and b are the two air flues answering to the
corresponding flues in Figures 3 and 7. A frame m has been placed across the
two flues, and this is furnished with two slots n and o, in which three slides p, 1,
can be moved horizontally. The slide consists of a single piece, and opens or
shuts the two flues a and b simultaneously according as to whether it is moved in
the direction of the arrow r, or in that of the arrow s. The two slides p can be
moved separately, so that the flue a can be opened or shut independently of the
flue b, and vice versa.
As will be understood from the above, the use of the described air heater_not
only enables one to heat the front, middle, or back part of an oven, more or less,
but by the employment of divided currents of air, a better use of the hot gases,
and therefore a saving of fuel, can also be effected.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. A counter current air heater, in which the hot air flues which are conducted
by the side of the air flues either in a straight line or zig-zag direction are
constructed in such a way that one or two walls of it serve as side walls for one or
two air flues, the latter also being constructed zig-zag shaped, so that the air
moves at least in one of the flues which form the whole of the air flue, opposite to
the direction of the hot air currents, as set forth.
2. A construction of the air heater claimed in Claim 1, in which several air
flues discharge the air into one heated collecting flue, as set forth.
3. A construction of the air heater claimed in Claim 1, in which the air heated
in each air flue or eventually in every group of air flues, is conducted to where it
is to be used separate from that of the other air flues or groups of air flues, as
set forth.
4. A construction of the air heater claimed in Claim 1, in which in one or more
of the flues, water pans are built in, over which passes the air which is to be
heated and which are pans heated from the side or from the bottom by the hot
gases, as set forth.
5. A construction of the air heater described in Claim 1, in which at the junction
of every group of air flues, are fixed double regulating slides or dampers of a
construction described in connection with Figures 15 and 16, as set forth.
Dated this 5th day of January 1895.
HENRY H. LEIGH,
Chartered Patent Agent.