IMPROVEMENTS IN KILNS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Thomas Carder at the Office
of the Commissioners of Patents on the 25th June 1881.
THOMAS CARDER, of Chudleigh, in the County of Devon, Brick and Pottery
Engineer. "IMPROVEMENTS IN KILNS."
This Invention relates to improvements in the construction and method of action
and of working a series of kilns or ovens of either continuous, semi-continuous, or
separate action, whereby great economy, facility of treatment in the burning or
firing stage, and greater uniformity of color and excellence of quality may be
secured than hitherto in brick, pottery, or clay productions, more particularly for
white and refractory clays from which fire bricks and tiles, white and buff terra
cotta goods, glazed, sanitary, and other pipes and pottery ware, are manufactured ;
the improvements being also applicable for the economic burning of blue brick and
quarries, Queen Anne red, and other bricks, tiles, and the like.
In carrying out my Invention I construct a series of two, three, four, or more
arched kilns or ovens, arranged in succession or in an elliptical or circular form,
whether for separate, semi-continuous, or continuous action as may be required,
each form of such kilns or ovens to be connected with a suitably placed chimney or
smoke shaft, and so constructed as to provide arrangements for feeding the kiln
furnaces with a hot blast of highly heated air. For this purpose I build flues from
the interior of one kiln leading through its buttress or foundation walls to the
exterior of the next or adjoining kiln, where I form openings in such flues in
front of or under the furnaces or fire holes at each burning, I temporarily build up
and enclose a space before each furnace of the "burning" chamber or kiln; into
this enclosed space the hot or incandescent oxygen flows or rises from the previous
or before "fired off" chamber, and is rapidly drawn through the coal introduced
into the furnace, thereby fiercely igniting it as with a blast, and carrying very
intense heat and flame into and throughout the whole of the kiln. These blast
flues are fitted with dampers so that the draught set up in the " 'burning
»

page_text: chamber may be made to cease to exhaust the hot air of the cooling chamber
at will.
I provide for the special careful drying off of the chambers set with green goods
beyond the burning chamber by means of the said blast flues, through which I
convey the hot air of the cooling kilns forward to such chambers, and so drive off
all or nearly all the moisture from the green goods before they become acted upon
by the full heat passing from the burning kiln, thus providing against general
discoloration and damage by rapid firing.
I arrange and construct the furnaces or fire boles so as to contain a vertical mass
of fuel, ranging from about two feet six inches to three feet six inches in height,
through which the external air or hot blast has to pass; and as this vertical mass of
fuel becomes incandescent by the ignition of the ever forming gas of the fuel, cold
air can with proper care be prevented from entering the burning chamber, a
desideratum which is very desirable in order to prevent the kiln crackles so
detrimental, but heretofore unavoidable by the ordinary methods of burning.
My improvements also relate to a peculiar and novel method of communication
between chamber and chamber with the means of disconnecting or "shutting off"
one chamber from another when desired.
"
For this purpose I first divide chamber from chamber by building a solid
partition wall from the floor level to the crown of the kilus. Below the floor level
and through the centre of each compartment or chamber I construct one, two, or
more perforated flues which meet or end in a spread flue or well at the end of the
chamber, and thence by means of one central flue pass under the division wall
into the next chamber bottom, where I provide a special arrangement by building
a stop or check to the bottom flue, about two feet distant from the division wall,
and above this point I build a feed pocket" extending from the floor level to the
crown of the kiln, and through the crown to the outside or main top of the kiln.
At the lower part of such "feed pocket "I leave an opening on one face, through
which the heated gases flowing under the division wall from the burning chamber
rise and spread throughout the chamber beyond. The top opening of this feed
pocket which passes through the crown I keep covered by a special iron cover to
prevent the inrush of cold air. From time to time, as necessary, I introduce fuel
down through this "feed pocket" in order to intensify the heat at this portion of
the kiln; and when necessary to disconnect one chamber from another I introduce
sufficient dust, coal, or sand down the "feed pocket" to completely block up and
close the opening of the flue leading from the previous chamber. I thus avoid the
usual loss of time in shifting iron doors, as is the case in the Hoffman kiln. I also
avoid the admission of cold air which usually takes place in the kilns at present in
use in the process of working from chamber to chamber.
"
I construct a crown flue" and a "bottom flue" to each of my kiln chambers, so
arranged as to unite into one flue before reaching the main or smoke flue. The
steam and smoke are thus taken off at two separate points in each chamber, and
the fumes of dissociated salt equally distributed in the process of salt glazing.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Carder in the Great Seal Patent Office on the 23rd
December 1881.
THOMAS CARDER, of Chudleigh, in the County of Devon, Brick and Pottery
Engineer. "IMPROVEMENTS IN KILNS."
This Invention relates to improvements in the construction and method of action
and of working a series of kilns or ovens of either continuous, semi-continuous, or
separate action, whereby great economy, facility of treatment in the burning or
firing stage, and greater uniformity of color and excellence of quality may be
secured than hitherto in brick, pottery, or clay productions, and more particularly
for white and refractory clays from which fire bricks, tiles, white and buff building
bricks, terra cotta goods, glazed sanitary and other pipes and pottery ware are
manufactured, the improvement being also applicable for the economic burning
of blue bricks and quarries, Queen Anne red, and other bricks and tiles, and the
like.
In carrying out my Invention I construct a series of arched kilns or ovens
arranged in succession, or in an elliptical, oblong, or circular form, whether for
separate, semi-continuous, or continuous action, as may be required by circum-
stances and the nature of the class of goods under process of burning, each form of
such kilns or ovens to be connected with a suitably placed chimney or vapour shaft,
and so arranged as to provide arrangements for feeding the kiln furnaces with a hot
blast of intensely heated air charged at a convenient point (or not charged, at the
will of the operator) with inflammable oils, gas, or bituminous or other hydro-carbon
products.
But to make my Invention better understood, I will proceed to describe the
same by reference to the accompanying Drawings, in which Figure 1, Sheet 1, is a
horizontal section or plan of half of an elliptical form of furnace or kiln con-
structed according to my Invention, and constructed with fourteen kilns or ovens;
Figure 2 is a part longitudinal section, and Figure 3 is a transverse section of same;
Figure 4 is a part outside elevation of the kilns, and Figure 5 is a view shewing
the main flue. Similar letters in all the Figures represent similar parts.
Although I have shewn in the Drawings my improved kiln arranged in an
elliptical form in plan, it will be understood that it may, as herein before described,
be arranged in other convenient forms.
In carrying out my Invention I build flues A (which I call hot blast flues) from
the interior of each kiln or chamber B, leading through its buttress or foundation
walls, as shewo, to the exterior of the next or adjoining kiln, where I form
openings C in such flues in front of or under the furnaces or fire holes D. At each
burning I temporarily enclose a space E before each furnace F of the burning
chamber or kiln by building around it, or by means of a portable iron enclosure.
Into this enclosed space E the hot or incandescent oxygen or hot air (charged or
not) at or near this enclosed space with inflammable oils, gas, or other hydro carbon
or bituminous products, flows or rises from the previous or before "fired off"
chamber, and is rapidly drawn through whatever kind of extra fuel may be
introduced into the furnace D, thereby fiercely igniting it as with a fiery blast, and
carrying very intense heat and flame into and throughout the whole of the kiln.
These blast flues A are fitted with openings and dampers, so that the draught set
up in the burning chamber may be controlled, increased, or shut off at will.
I provide for the special-careful drying off of the chambers set with green goods

page_text: beyond the burning chamber by means of the said blast flues A, through which I
convey the hot air of the cooling kilns, uncharged with fuel for a short period,
forward to such green or newly filled chambers ahead, and so drive off all or nearly
all the moisture from the green goods before they become acted upon by the full
heat passing from the burning kiln, thus providing against general discoloration and
damage which would be caused by a too rapid firing.
I arrange and construct the furnaces or fire holes D so as to contain a vertical
mass of fuel-ranging from about twenty four inches to forty two inches, more or
less in height, through which the external air or hot blast and its chargings has to
pass, and as this vertical mass of fuel becomes incandescent by the ignition of the
ever forming gas of the fuel, cold air can here with proper care be prevented from
entering the burning chamber, a desideratum which is very desirable, in order to
prevent the kiln crackles so detrimental, but heretofore unavoidable, by the ordinary
methods of burning.
My improvements also relate to a peculiar and novel method of communication
between chamber and chamber, with the means of disconnecting or shutting off one
chamber from another when desired.
For this purpose I first divide chamber from chamber by building a solid
partition wall F from the floor level to the crown of the kiln. Below the floor
level and through the centre of each chamber or compartment B I construct one,
two, or more perforated flues G which meet or end in a widened or spread flue or
well H at the end of each chamber, and continue by means of one central flue
under the division wall F into the next chamber; at this point I provide a special
arrangement by building a stop or check I in the bottom flue G, about two feet,
more or less, from the division wall F, and above this point I build and arrange a
feed pocket J extending or reaching from the floor level to the crown of each kiln
or chamber, and through the crown to the main top or outside top part of the kiln
as shewn. At the lower part of one face of such feed pocket J I leave or construct
an opening K through which the heated gases flowing under the division wall from
the burning chamber rise and spread throughout the chamber beyond. The top
opening of the feed pocket J which passes through the crown I keep covered by a
suitable portable iron cover to prevent the inrush of cold air; from time to time as
necessary I introduce fuel down through this feed pocket, in order to intensify the
heat at this portion of the kiln, and when the state or condition of the burning
chamber renders it necessary to disconnect the burning chamber from the previous
or cooling chamber I introduce sufficient dust, coal, ashes, or sand down the feed
pocket to completely block up and close the opening of the bottom flue G leading
from the previous chamber. I thus avoid the usual loss of time in shifting the
usual iron doors employed in many other systems of kilns; I also avoid the
admittance of cold air in thus disconnecting or connecting one chamber from or
with another chamber. I construct a crown flue L and a bottom flue M to each of
my kiln chambers, so arranged as to unite into one flue before reaching the main
flue N. The steam and smoke are thus taken off at two separate points in each
chamber, and when the process of salt glazing is being conducted, the fumes of
dissociated salt are equally distributed and drawn off. O are wicket ways;
P, openings to admit cold air; Q, sight holes; R, firing tunnel; S, tunnel passage;
and T, the shaft or chimney.
I will now describe the method to be followed in the practical working of a kiln
constructed according to my Invention, it being understood that in the description
the terms kiln, oven, and chamber, refer equally to the separate compartments for
burning bricks and other goods into which the entire kiln is divided by the
division walls F, and the chambers or kilns are numbered successively 1, 2, 3, 4, 5,
6, 7, 8, only eight chambers being shown in Figure 1, Sheet 1, of the Drawing.
During the process of "firing off," say, No. 1 chamber, the heated gases and
vapours of combustion have been conducted into No. 2 chamber by means of the
bottom flue G, and from No. 2 chamber on to No. 3 chamber also, if required, thus
·

page_text: highly heating chambers Nos. 2 and 3 by the waste heat from chamber No. 1 or
the burning chamber for the time being. Chamber No. 4 is disconnected from
chambers Nos. 1, 2, and 3 by means of a damper let down through the feed
pocket J, and the heated vapours are then directed away to the main flue N by
means of the crown flue L and kiln flue M, the damper of which is lifted in the
main flue, chamber No. 1 having being fired off. Chamber No. 2 is disconnected
by means of coal dust, ashes, or sand being introduced down the feed pocket by
which the bottom flue G is blocked up. The dampers of the hot blast flues A are
then raised and the openings of the same in front of or under the furnaces of
chamber No. 2 opened and here charged or supplied (or not charged at will) with
inflammable products, as before mentioned, and rapidly drawn into and through
the furnaces of chamber No. 2, filling the whole chamber with fierce flame,
chamber No. 1 thus supplies the heated air or oxygen necessary for combustion, a
temporary covered space having been made in front of the furnaces of chamber No. 2,
as shewn in dotted lines at E in the cross section, Figure 3. Chamber No. 2 having
been fired off it will be found that chamber No. 1 has been much cooled by the
abstraction of its heated gases, and its remaining heat is or can be then passed
forward to chambers Nos. 4 and 5 for slowly driving off the moisture of the green
goods which may have been placed therein, whilst chamber No. 3 is supplied with
hot air from chamber No. 2. These operations are repeated until the whole circuit
of the chambers has been made or the whole series of kilns burnt.
Having now particularly described and ascertained the nature of my said
Invention, and the method by which the same is or may be carried into effect, I
would observe that I do not confine myself to the precise details herein laid down,
but what I consider to be novel and original and intend to be protected by the
herein in part recited Letters Patent is,-
Firstly. The general arrangement and construction of the improved kiln, operating
substantially in the manner and for the purposes herein before described and
represented in the accompanying Drawings, or any mere modification thereof.
Secondly. The peculiar arrangement of a hot air or hot blast flue, such as A, on
the external and internal sides of each kiln or chamber of a series, whereby each
burning chamber is supplied with a sharp current or currents of hot air from the
previously fired chamber, such hot currents being either charged or supplied (or
not) with inflammable oils, bituminous products, gas, or other hydro-carbon products
on their way to the furnaces beyond, as herein before described.
Thirdly. The building a temporary enclosure or placing a portable iron enclosure
before each furnace of the burning chamber, whereby the cold atmospheric air is
excluded, such small enclosed space forming a combustion chamber in which the hot
air from the hot blast flue enters to combine with the gases or fuel otherwise
introduced for passage through the furnaces to the interior of the kiln, as herein-
before described.
Fourthly. The arrangement of the bottom flue with spread flue and a check or
block under the opening of the feed pocket, by which means the waste heat of the
burning chamber is caused to rise in the chamber or chambers beyond, as herein-
before described and represented in the accompanying Drawings.
Fifthly. The novel arrangement of feed pocket which admits of a damper being
lowered to shut off the " green " chambers already "set" beyond the burning
chamber from the chambers further beyond in process of being set or refilled with
bricks or other goods, as hereinbefore described.
Sixthly. The use of the feed pockets for supplying the kiln with fuel, as herein-
before described, and more particularly for shutting off or disconnecting the cooling
chamber from the burning chamber at this point by means of coal dust, ashes, or
sand introduced through the pocket from the top of the kiln, whereby the flue G is
blocked at the bottom, as hereinbefore described.
Seventhly. The method of further using the waste heat of the cooling chambers

page_text: by separately passing it forward to the green chambers in advance of those beyond
or in connection with the burning chamber, as herein before described.
In witness whereof, I, the said Thomas Carder, have hereto set my hand and
seal, this Twenty second day of December, in the year of our Lord One
thousand eight hundred and eighty one.
Signed, sealed, and delivered
by the said Thomas Carder
in the presence of
STEPHEN B. SUTTON,
Solч.,
Bideford.
THOMAS CARDER. (L.S.)