An Improved Hoffman or Continuous Kiln for Drying and Burning Bricks and other Goods.
Year: 1893

page_text: Date of Application, 21st Oct., 1893
Complete Specification Left, 21st July, 1894-Accepted, 8th Sept., 1894
PROVISIONAL SPECIFICATION.
An Improved Hoffman or Continuous Kiln for Drying and Burning
Bricks and other Goods.
RICHARD COOK of Hillcrest Kensal Risc in the County of Middlesex Brick
Manufacturer do hereby declare the nature of this invention to be as follows:-
The object of this invention is to enable the manufacture of bricks or other
articles from plastic and other clays being in wet state to be carried on in winter
as well as in summer and for drying the same to utilize the waste heat from the
burnt chambers of a continuous kiln which are in the process of cooling. Also to
avoid the necessity of the bricks being handled while in a soft state; or of their
being required to bear any weight until they are well advanced in the process of
drying; and of the colour being deteriorated by smudging while in too damp a
state in the kiln.
In order to accomplish this I form a tunnel or drying chamber between two
parallel rows of firing chambers of a continuous kiln. Along this tunnel which may
be extended to any required length are laid tramways and the bricks or other goods
are placed on trolleys moving along the rails gradually till they become dry. The
waste heat from the burnt bricks is turned into this tunnel.
This invention also comprises the method of constructing the roofs of the
chambers of kilns. They are formed of steel or iron joists which are encased in
perforated bricks of special make grooved to fit the joists so that the fire only
reaches the metal to a small extent. By this means the crowns of the firing
chambers can be formed square instead of arched as usual which not only increases
the quantity of goods the chambers will hold but is much more convenient for
packing the goods.
Dated Li
11000
COMPLETE SPECIFICATION.
An Improved Hoffman or Continuous Kiln for Drying and Burning
Bricks and other Goods.
I RICHARD COOK of Hillcrest Kensal Rise in the County of Middlesex Brick
Manufacturer 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 :-
23
This invention relates to what are known as "Hoffman or continuous kilns for
burning bricks and other articles and to the method of drying the goods before
stacking them in the kiln the chief objects being to enable the manufacture of
bricks from plastic and other clays in a wet state to be carried on uniformly and
expeditiously without the use of drying floors all the year round and irrespective of
weather as is done in the case of semi-dry brick manufacture and with but little
delay or additional outlay for fuel or labor to keep up a constant supply of goods
in a dry or nearly dry condition ready for burning in continuous kilns. Also to dry
the bricks mainly by the spare heat from the chambers in which the burnt bricks
are in the later stage of cooling, to dispense with the handling of the bricks while
soft after leaving the machine and to provide a very gradual but constant increase
of temperature for the wet bricks which prevents cracking and ensures a much
better colour when burnt.

page_text: In order to accomplish the above the kiln as shown on the accompanying drawings
is constructed with 14 firing chambers (but the number may be greater or less)
arranged in two rows of 7 on each side separated through their whole length by a
space of about 12 feet in the upper part of which intermediate space is the drying
chamber giving room for 3 lines of trolleys to be brought through abreast, and in
the underneath part of the 12 ft. is the smoke chamber connected with the chimney
shaft as well as the interchanging flue hereafter described.
This tunnel or drying chamber is continued from the kiln to any length desired
so as to load the bricks upon trolleys at the brick machine by means of pallet
boards which are placed upon the trolleys in tiers and resting on cross bars so that
the air can pass freely on all sides of the bricks.
When the trolleys are loaded they are run into the tunnel upon rails laid at an
inclination that will cause them to move forward automatically as the dried articles
are taken out at the lower end.
This tunnel is made as far as possible air tight throughout its entire length in
order that there may be a strong current of hot air passing in at the lower end and
out at the upper end and there is no communication whatever between the chambers
under fire or the smoke chamber and this tunnel or drying chamber so that no
smoke can come into contact with the wet bricks.
The volume of hot air passing through the tunnel can be increased by means of
an exhaust fan or a ventilating shaft placed at the upper end of the tunnel which
will help to draw the hot air out of the chambers of the kiln which are in the
cooling stage.
In order to more fully explain the nature and practical working of this invention
I have annexed the accompanying drawings upon which the same parts are
indicated throughout by the same letters.
Fig. 1. is a ground plan or horizontal section showing the position of the
several parts both below and above the floor of the drying chamber.
Fig. 2. is a vertical section of the kiln lengthways.
Fig. 3 is a cross section of the same.
Fig. 4 shows the method of constructing the roof of kiln with iron or steel
joists and perforated bricks or lumps resting on and grooved into the joists and the
space above filled in with concrete.
Fig. 5. is a section of the trolleys on which the bricks are conveyed through
the tunnel showing the method of placing the pallets on movable bars resting on
the uprights of the trolleys.
Fig. 6 is a side elevation of saine.
Nos. 1. to 14 represent the firing chambers of the kiln in which the bricks
are burnt.
F.C indicates firing chambers.
S.F indicates smoke flue.
D.C is the drying chamber within the kiln.
D.T is the drying tunnel continued outside the kiln.
G. is the gangways for loading and unloading.
C.S is the chimney shaft.
T.F is the flues leading from the firing chambers into the tunnel or drying chamber.
I.F indicates the interchanging flue.
T.L is the tramways for trolleys.
C. is the cross flues connecting the firing chambers at either end of the kiln.
X. indicates the two auxiliary firing holes.
S.D is the dampers leading into the smoke flues.
I.V is the interchanging valve to each chamber.
P.F indicates the dampers and flues for the passage of the fire from chamber to
chamber.
S. standards of trolleys.
J. means iron or steel joists.

page_text: There are 4 sets of dampers which are used for 4 distinct purposes, those
marked S.D are for connecting each chamber with the smoke flue and the chimney
shaft, those marked P.F are for separating when necessary each firing chamber
from those both before and behind it so that each chamber can be completely shut
off from the others as is sometimes required; those marked T.F are for allowing
the waste heat from the burnt chambers which are in the second stage of cooling to
pass into the drying chamber or tunnel; those marked I.V. are for conveying the
hot air from any chamber which has been burnt into any other chamber newly set
with green bricks so that they may be more thoroughly dried and made hot by
means of the dry heat before any smoke or vapour comes into contact with them. \.
When this drying is completed and it is desired to admit the advancing fire into
another chamber the dampers marked P.F in the parting wall next the advancing
fire must be lifted and those in the forward part of such chamber closed.
In the rear of the firing chambers when a chamber has for some time ceased to
be fired and is no longer required to supply heat to the chamber which is being
fired the dampers marked P.F situate in the lower part of the parting wall are
closed and the valves I.V. are opened to allow the waste heat from such chamber
to be drawn off by means of the interchanging flue marked I.F and conveyed into
the chamber last filled with green bricks as before described.
When a sufficient supply of heat has been drawn off from a cooling chamber for
this last mentioned purpose the valve marked I.V can be closed and the valves
marked T.F can be opened to allow the heat to pass off into the tunnel or drying
chamber marked D.C where the newly made bricks are upon the trolleys and at
the same time some fresh air can be admitted at the lower part of the gangway of
such chamber to facilitate the current and the process of cooling.
Each of the 14 firing chambers of the kiln has at the foot of its forward parting
wall a flue leading into the smoke chamber, but in the case of the 4 corner chambers
this flue has to be altered in position as shown on the drawings in Fig. 1.
Each firing chamber has also in the upper part of the inside wall 2 openings into
the drying chamber or tunnel which are closed with valves T.F and opened as
described when it is desired to allow the waste heat from the chamber in the later
stage of cooling to escape and pass into the tunnel.
Each firing chamber is divided from the others by a parting wall extending from
floor to roof and in which there are 4 or 5 openings closed when required by means
of dampers marked P.F and worked from the top of the kiln.
The roof or crown of the firing chambers and also of the drying chamber is
formed by iron or steel joists placed 14 inches to 18 inches apart and into the
bottom flange of such joists is grooved perforated bricks or lumps as shown upon
the drawings and above these is placed a layer of cement concrete to any desired
thickness.
-
The chimney shaft which is placed apart from the kiln, the mode of building
the walls of the kiln, the firing holes in the top of the kiln, the gangways for
loading and unloading the chambers, the mode of placing the bricks in the kiln for
burning are of the usual kind and need not be more particularly described but are
indicated for completeness.
In the tunnel or drying chamber within the length of the kiln and between the
two rows of firing chambers two partitions are erected of brick or sheet iron and
covered in at the top by means of sheet iron or other suitable material thus making
a tunuel within a tunnel, and this inner tunnel extends the entire length of the kiln
except about 6 ft. at the lower end, the object of this is to make the hot air drawn
from the firing chambers to enter the inner tunnel where the trolleys of bricks are
at the lower end and thus pass through its entire length, also ensuring that those
bricks which have been in the longest shall have the greatest heat.
The tunnel or drying chamber within the kiln is separated from the smoke
chamber or flue which is underneath it by means of iron joists placed transversely
and upon the lower flange of these joists is placed and suitably secured and
rendered air tight sheets of iron thus allowing a great deal of the heat passing

page_text: through to the shaft to be absorbed and assist in the drying of the bricks in
the tunnel.
In order more fully to explain the working of the interchanging flue 1.F suppose
as an instance the chargber of the kiln numbered 9. has just been filled with green
bricks which it is desired to steam by means of dry heat the chamber No. I has
probably ceased firing 2 days and in order to draw the waste heat out of this
chamber into No. 9 the dampers P.F on both sides of No. 1 must be closed and
the valve I.V. of this chamber opened. Also the valve I.V. of No. 8 must_be
opened the dampers P.F of No. 8 passing into No. 9 opened and the smoke valve
of No. 9 must be opened to allow the through current of air to operate by means of
the chimney shaft, also it will be necessary to close the dampers P.F of No. 9
leading into No. 10.
The two firing holes marked X. are for the purpose of assisting to bring the fire
across the intervening space between chambers Nos. 6 and 7 and Nos. 13 and 14, a
similar fire can be lighted in the gangways of chambers Nos. 7 and 14 to assist in
the same purpose.
The trolleys are so far as the bed or frame is concerned made in the ordinary
way but there are 4 standards one at each corner screwed down to the frame and i
braced together with cross braces as shown. These standards are made with
notches about 7 inches apart in which rest iron bars running lengthways on both
sides across which the pallets are placed. The pallets are made with 2 ledges on
the under side placed the same width apart as the bars upon which they rest to
prevent side slipping.
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 I
claim is
1. The construction of a continuous kiln with two rows of firing chambers
arranged and connected substantially in the manner and for the purpose set forth.
2. The construction of a chamber for drying bricks or other goods formed'
between the two rows of firing chambers of a continuous kiln and into which
chamber the waste heat from the burnt goods in the process of cooling can be
brought.
3. The construction of a tunnel leading into such chamber as last mentioned
and being a continuation of the same to any length required beyond the kiln
and through which the bricks or other goods are passed on trolleys or otherwise.
4. The method of drawing the waste heat out of the cooling chambers and
of producing a current of hot air through the whole length of the drying
tunnel by the application of the fan or exhaust shaft at the upper end of such
tunnel.
5. The construction of the smoke chamber underneath the drying chamber
in the manner described so as to get additional heat which would otherwise
be lost.
6. The construction of the roofs or crowns of chambers with iron and perforated
bricks or lumps so described rendering them fireproof.
7. The construction of an interchanging flue by means of which the waste heat
from any chamber which is cooling can be conveyed into any chamber set with
green bricks substantially in the manner set forth.
8. The method of forming the uprights or standards of the trolleys and
of placing the cross bars and of securing the pallets on the trolleys as set forth.
Dated this 21st day of July 1894.
RICHD. COOK.