IMPROVEMENTS IN REGENERATIVE HOT AIR FURNACES
Year: 1885

page_text: Heating Air.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex do hereby declare the nature of the invention for "IMPROVEMENTS IN
REGENERATIVE HOT AIR FURNACES" (a communication to me from abroad by
Emile Fourcault, of Lodelinsart, and Ernest Jacques, of Dampremy, both in the
Kingdom of Belgium, Engineers) to be as follows:-
This invention relates to regenerative furnaces or stoves in which burning
gases from furnaces are utilized for the purpose of heating air to a high temperature,
to be subsequently used in glass furnaces or furnaces used in metallurgy. The
improved stove is based upon the same principle as what is known as the Ponsard
regenerator, the burning gases from the furnace transmitting their heat to the air
through sufficiently thin walls.
The apparatus is constructed of specially formed refractory bricks about
14 inches by 7 inches x 4 inches and each having two holes through it about
4 inches square. The exterior walls of the holes are therefore about 18 inches
thick and the partition between them about 3 inches.
It will be seen that by building up these bricks one above the other, making the
break joint in the usual way, a wall will be obtained about 7 inches thick and of
any desired height and length, having vertical channels through it for the passage
of the air to be heated about 31 inches apart, and two heating surfaces which
utilize the hot gases and products of combustion as they pass to the chimney.
The arrangement of the joints and the large faces of the bricks ensure the
stability of the mass.
In order to form the tops of these masses of channelled brickwork, special bricks
are used, of half the length only and having but one hole, or about 7+ inches by
7 inches by 4 inches.
By arranging hollow or channelled walls side by side, and at distances apart
which may be varied more or less, a mass of brickwork can be obtained having

page_text: spaces through which are made to circulate between the walls the burning gas and
products of combustion on their way to the chimney.
The greater the distance between the several walls the less will be the useful
effect of the heat, but six inches may be estimated as the minimum distance.
The perforated or channelled masses are built upon a flat foundation of ordinary
brickwork, two or three courses of perforated bricks being first laid, care being
taken to leave a lateral aperture about 4 inches square into the bottom of each of
the vertical passages or channels, for the admission of the air which is easily done
by removing part of the side of the brick, or better by the use of specially made
bricks.
Twice as many rows of bricks will be laid as there are masses to be built, a
space of 6 inches being left between the rows. The narrow spaces thus formed
between the masses serve to conduct the cold air which is admitted from external
openings into the ends of the spaces, to the vertical passages. To form the covering
of these spaces so as to separate the cold air from the hot gases above three courses
of flat bricks or tiles are used, laid so as to break joint, and measuring about
9 inches by 7 inches by 2 inches, small tiles about 3 inches by 4 inches by
24 inches being arranged between the rising passages so as to keep the flat bricks
or tiles from shifting laterally..
The building of the masses of hollow bricks is then continued upward to the
required height as already described. The hot gases may be made to take three
horizontal turns from right to left between the walls of hollow bricks, two
horizontal hollow partitions being arranged at suitable heights and formed of flat
tiles separated by a course of hollow bricks, cold air being admitted into the
partitions from one end and being utilized by passing it when hot through a lateral
opening at the other or closed end into the second vertical hot air channel from
such other end, the circulation of air thus obtained preventing the fusion of the
bricks which form the partition. An arched reservoir for the air when hot is
built in the upper part of the furnace or stove above the cover of the mass of
vertical hot air passages and intermediate gas channels which form the regenerator,
this cover being similar to the lower course above the cold air channels already
described.
The heated gases from a furnace are admitted from above at one end of the
upper spaces below the hot air reservoir and above the uppermost horizontal
partition, and pass forward along to the other end of the space into a vertical
chamber returning under the upper partition into a similar chamber at the end at
which they entered, thence forward below the lower partition and above the
covering floor, which is built over the entrance passages for the cold air as already
described, to the lower part of the vertical chamber, whence they pass away
through a flue.
The highly heated air in the upper arched reservoirs is conducted away through
suitable passages and utilized as desired in furnaces.
Two entire furnaces or sets of apparatus built and constructed as described are
arranged side by side, suitable dampers or valves being used by which the
admission of the heated gases can be regulated.
The method described of utilizing the wasted heat gases from furnaces differs
from such apparatus as heretofore used in being composed of two chambers entirely
separate, so that the draft at the two sides of the furnace can be regulated with
great facility, and also in the transverse course given to the hot gases in their
passage, the channels ordinarily required through which the hot gases are returned
being thus unnecessary, and the resistance to draft and loss of heat being avoided.
The independent separation of the currents of hot gases can also be carried further.
In the arrangement above described, it is assumed that each of the chambers
through which the gases pass at the ends of the mass of perforated brickwork, is
divided in plan into four parts, and each regenerator.consists consequently of four
separate or independent compartments the draft in each of which may be regulated
separately so as to obtain a practically uniform temperature in the apparatus. In
"'

page_text: case of accident or other cause either compartment may be shut off from the others
for the purpose of rebuilding or repairing it.
The system of transverse currents for the heated gases allows the length of the
passages to be reduced, and great advantage is thus obtained in cleaning as very
long passages are very liable to be injured by the tools used in such cleaning.
Apparatus constructed as described according to this invention is also very firm
and durable, and not liable to accidental displacement of its several parts as where
solid bricks are used, nor does it present a great number of vertical joints which
would be liable to open communication between the horizontal currents of heated
gases and the vertical ones of air, a displacement of 14 inches in no way affecting
the tightness of the joints.
In ordinary regenerators in which thin tiles or bricks are used exposed on both
sides to intense heat, these are rapidly destroyed, and the divisions by which the
heated gases are made to circulate are equally perishable.
In mining districts too, and where the foundations are bad or in the neighbourhood
of heavy hammers, such regenerators rapidly deteriorate.
In the improved apparatus described, on the other hand, by the method of
introducing the cold air laterally, the use of perforated bricks having ample base,
and the hollow separating partitions through which air circulates, these difficulties
are avoided. On bad foundations vertical and transverse ties or stays of iron may
be used to keep the masses of perforated brick work in place.
-
In order to obtain the best result, the regenerative furnace should be so
proportioned and arranged that the air is forced through the vertical passages very
slowly, and this is effected by using a very large number of these passages, so as to
obtain a large area of passage and great heating surface, the air travelling slowly
and being exposed for a long time to the action of the heat in the regenerator.
The improved apparatus may be varied more or less in its method of arrangement
and construction. It may be built so as to operate singly or in pairs, and in some
cases where unavoidable, the circulation of gases may be longitudinal instead of
transverse, and the furnace may be circular, rectangular, or of other suitable shape.
Dated this 9th day of September 1885.

page_text: COMPLETE SPECIFICATION.
0
Improvements in Regenerative Furnaces or Stoves for
Heating Air.
1, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
.Middlesex do hereby declare the nature of this invention (a communication to me
from abroad by Emile Fourcault of Lodelinsart and Ernest Jacques, of Dampremy,
both in the Kingdom of Belgium, Engineers) and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement and accompanying drawings (that is to say):-
3
This invention relates to regenerative furnaces or stoves in which burning gases
from furnaces are utilized for the purpose of heating air to a high temperature,
to be subsequently used in glass furnaces or furnaces used in metallurgy. The
improved stove is based upon the same principle as what is known as the Ponsard
regenerator the burning gases from the furnaces transmitting their heat to the air
through sufficiently thin walls.
.
In the accompanying drawings which are in illustration of the invention, figure 1
is a vertical section through a pair of the improved stoves, the right hand stove
being shewn in section through the vertical air passages on the line E. F. figure 2,
and the left hand stove through the passages for the heated gases on the line C. D.
figure 2; Figure 2 a horizontal section through the same; Figure is a vertical
section, on a larger scale, through the passages for the hot gases and the air;
figure 4 is a similar vertical section, shewing one of the passages for the heated
gases, and the hollow horizontal dividing partitions; Figure 5 is a plan of figure 3;
and Figures 6, 7, and 8 shew in detail the shape of the hollow bricks which are
used in building the heating surfaces of the stove. The plain arrows shew the
course of the cold air; the half-feathered arrows of the heated air, and the feathered
arrows of the hot gases. Similar letters refer to similar parts throughout the
several figures.
The bricks of refractory material which constitute the heating surface of the
stove are shewn in figures 6, 7, and 8, and are preferably about 14 inches long
by 7 inches wide, and 4 inches thick, each having two square holes a, a, through
it about 4 inches square, the exterior walls therefore being 18 inches thick and
the partition b between them about 3 inches thick. It will be seen in figure 6
that a wall built with these bricks, making them break joint in the usual way,
will be 7 inches thick and any desired height and length, having square vertical
passages through it, and the arrangement of the joints and the large faces of the
bricks ensure the stability of the wall.
=
We build a series of parallel walls of these bricks, as shewn in figures 1 and 2,
a space being left between each two walls of about six inches, and each stove
consists of a sufficient number of these parallel walls c, c, c, having vertical
passages a through them. The walls are built upon a flat foundation of masonry
at d', and after the first two or three courses have been laid the spaces between
the walls are covered with a sufficient thickness of flat bricks or tiles e laid so as to

page_text: break joint, and serving to separate the cold air to be heated which is admitted
from outside the stove into the space between the walls and thence through lateral
apertures d, d, d, into the vertical channels a, from the hot gases which are made
to circulate between the walls. Above the tiles e, the building of the walls is
continued upward to the desired height, their upper ends being covered with a
sufficient thickness of flat bricks or tiles f, having perforations corresponding with
the passages a in the walls, and above the covering f is built an arched reservoir
for the air after it has been heated.
g
The heating gases which are admitted from the furnace where they are produced,
through the passages at the top of the stove are made to circulate backward and
forward between the walls c before passing into the flue i to the chimney.
For this purpose horizontal partitions k, k¹, are built across the walls cat
different heights, closing the chambers 7, 1, alternately, so that the gases are forced
to circulate in the direction shewn by the arrows in figures 1 and 4. These
partitions are made hollow as shewn in figures 1, 3, and 4 air being admitted into
them, either through the external wall of the stove m, or through a passage o in
the central wall n which divides the pair of stoves, as shewn in figures 1 and 4.
The partitions k, k', are formed of flat tiles above and below, separated by hollow
perforated bricks a, and having openings through them corresponding with the
openings in the bricks. The air which enters the hollow partitions k, k³, becomes
heated and escapes through lateral openings p into the adjoining vertical passage a.
The heated gases admitted through the passages h into the upper part of the
chamber circulate below the hot air receivers g and between the walls a to the
chamber thence back under the partition k to the chamber l, and again forward
under the partition k and above the covering e to the chamber and through the
flue i to a chimney. At the same time cold air enters from r to the spaces between
the walls below the covering e and thence passes through the openings & up through
the vertical passages a in the walls into the receivers g becoming highly heated in
its passage.
d
From the receivers g it can be conducted away and utilized. Small square
tiles (figure 5) are fitted between the perforations a, to keep the tiles from
shifting.
Each of the pair of stoves is divided into four or more parts by divisions 8, 8, 8,
formed by carrying the corresponding walls a to the outer wall of the stove, and
by arranging valves or moveable dampers of any of the ordinary well known kinds
at t in the entrance passages h and the exit passages to the flue i, any of these
separate parts of the stove can be readily cut off from the remainder, for the
purpose of cleaning or repair, and the heat of the several parts and of each of the
stoves can be adjusted and regulated so as to maintain a practically uniform
temperature.
By the system of transverse currents backward and forward for the heated gases,
the length of the passages in which deposit accumulates and which consequently
require cleaning is greatly reduced, and facility in such cleaning is obtained, such
short passages not being liable to injury by the tools used.
The novel heating apparatus described is very firm and durable, and the hollow
walls are not so liable to accidental displacement of their several parts as where
solid bricks are used, nor do they present a great number of vertical joints which
would be liable to open a communication between the horizontal currents of heated
gases between the walls, and the vertical currents of air in the walls, a lateral
displacement of 14 inches not affecting the tightness of the joints.
In regenerator stoves, where thin tiles or bricks exposed on both sides to
intense heat have been used, they have been rapidly destroyed, and any divisions
or partitions by which the heated gases are made to circulate have been equally
perishable, but in the improved stove on the other hand, by the method of intro-
ducing the cold air laterally, the use of perforated bricks having ample base, and
the hollow separating partitions k, k³, through which air circulates, these difficulties
are avoided.

page_text: On bad foundations, vertical and transverse ties or stays of iron may be used to
keep the walls of perforated brick work in place.
In order to obtain the best result, the regenerator stove should be so proportioned
and arranged that the air passes very slowly through the vertical passages a in the
walls, and this is effected by using a very large number of these passages so as to
have a large area of passage and great heating surface, the air travelling slowly
and being exposed for a long time to the action of the heat.
The stoves may be used single or in pairs as shewn, and may be square,
rectangular, or of other convenient shape, and their size and proportions may be
varied according to the particular purpose and the circumstances in which they are
to be used.
Having now particularly described the nature of the said invention and in what
manner the same is to be performed, I declare that what I claim is :-
1. In combination, the parallel walls c perforations a, hollow horizontal parti-
tions k, k¹, and air inlet openings r and o, chambers 1, 1, gas passages h, and flues i,
substantially as and for the purposes described and shewn.
2. The combination of the parallel walls c and perforations a, inlet cold air
openings d, perforated coverings e and f; vertical hollow partitions 8, hot air
receiver g, and regulating valves t, substantially as and for the purposes described
and shewn.
3. The flat rectangular bricks, perforated with square holes a, and forming the
heating surface of the regenerator as walls c, substantially as described and shewn.
Dated this 9th day of June 1886.
EDWARDS & Co.,
Agents for the Inventors.