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Oct. 15, 1946.
w. E.'HESSMAN
2,409,205
METHOD AND APPARATUS FOR CALCINING MATERIALS
Filed April 9, 1941
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METHOD AND APPARATUS FOR CALCINING MATERIALS
Filed April 9, 1941
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INVENTOR
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BY
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‘ M 15, 1946.
w. E. HESSMAN
2,409,206
METHOD AND APPARATUS FOR CALCINING MATERIALS
Filed April 9, 1941
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INVENTOR
Patented Oct. 15, 1946
2,409,206 '
UNETED STATES PATENT OFFICE
2,409,206} _
METHOD AND APPARATUS For; CALCINING
MATERIALS
.
7
William E. Hessman, Luckey," 'O'hio, assignorr to
National Gypsum Company, Bu?alo, N. Y.
Application April 9, 1941, Serial No. 387,625
21 Claims.
1
This invention relates to means for and a
method of calcining limestone to produce lime
or for analogous industrial processes.
It is well known in the art to use a plurality
of furnaces each of which is arranged to dis
charge its gaseous products of combustion di
rectly into a common kiln. The present invention
may be said to present two principal aspects of
novelty. One is in the provision of a single fur
(Cl. 263-53)
2
A marked saving in the consumption of the
solid fuel herein contemplated and a very much
increased e?ioiency in extracting the heat energy
therefrom is evidenced by use of the foregoing
draft arrangement.
As stated above, my present invention further
comprehends the application of the foregoing
draft arrangement to a plurality of furnaces
which serve a common kiln.
Such furnaces are
nace having a novel draft arrangement, in and 10 normally arranged to discharge their gaseous
of itself, and the other resides in correlating the
products of combustion into the kiln at points
draft arrangements in a group of furnaces serv
spaced thereabout. I provide means whereby the
ing a common kiln.
operation of a number of furnaces related to one
Having reference to the present invention inso
kiln operate successively with respect to their
far as it concerns the disclosure of a novel draft 15 forced blast impulses so that the inrushing im
valve arrangement for a single furnace, my inven
tion resides in alternately driving hot gaseous
products of combustion upwardly out of the fuel
bed of the fire in the furnace and then driving
pulses of hot gaseous products to the kiln from
the several furnaces is uniformly staggered as to
time.
This arrangement
a blast of air across the combustion chamber over 20 greatly improve the
the fuel bed and toward the associated lime kiln
of heat in the kiln
to move the hot gaseous products into immediate
improved calcination
is found to still further
uniformity of distribution
with a consequent greatly
of the charge therein. The
swirling and surging of the variously directed
and direct contact with the charge in the kiln.
This mode of operation is repeated successively
pulsating impulses of hot gases in the kiln serves
and alternately substantially throughout the
to substantially prevent channeling of the heat
through the kiln and pocketing of the heat
therein. An ‘important end which is served by
period of operation of the furnace. The blasts
are of relatively short duration and succeed each
other at a rate calculated to produce pulsating
operation according to my invention is the driv
surges of heat energy.
ing off of the relatively heavy carbon dioxide
I have found that the Swirling and surging 30 gases from the limestone in the kiln and a forcible
action produced in this manner operates in a very
ejection of such gases at the top thereof.
substantial way to avoid the usual channeling
The pulsating impulses of the hot gases from
and pocketing of hot gases through and in the
the several furnaces produce a buifeting about of
charge of the kiln and results in a highly uniform
the hot gases through the mass of limestone.
calcination of the charge by virtue of a very
The relatively uniform distribution of heat in the
greatly increased uniformity of heat distribution
kiln permits complete calcination of the charge
at less extreme maximum temperatures than
heretofore with a consequently greatly increased
the foregoing is preferably supplementedby pro
life of the kiln lining. As previously pursued,
viding automatic operation of natural draft valves 40 conventional lime kiln methods have resulted in
associated with both the ash pit and the combus
the necessity of rather frequent repair of the
tion chamber of a furnace. By such automatic
kiln lining due principally to pocketing of heat
operation I propose to arrange the natural draft
locally in the charge adjacent the kiln lining.
valve leading to the ash pit to be automatically
While a single speci?c embodiment of appara
closed when a forced blast of air is directed. into 45 tus capable of achieving the foregoing objectives
the ash pit and open when a forced blast is di
is illustrated in the accompanying drawings and
rected over the fuel bed in the combustion
described in detail below, it is to be understood
chamber.
that the operating principles herein contemplated
Similarly, but conversely, I propose to provide
may be followed in a number of ways and with
a natural draft valve communicating directly with 50 considerable variation in the speci?c apparatus
the combustion chamber above the fuel bed which
employed. Accordingly, my invention is not to
is automatically closed when a forced blast of air
be considered as limited otherwise than as de
is driven across the top of the fuel bed and auto
?ned in the appended claims.
matically open when the ash pit forced blast is
In the drawings:
in the kiln.
The general scheme of operation set forth in
applied.
55
v Fig. l is a fragmentary elevational View of a
2,409,206
3
lime kiln having associated therewith a plurality
of furnaces, the view being partly in cross section
for added clearness;
Figure 2 is a fragmentary elevational view of
the lime kiln of Fig. 1 showing the same portion
thereof but viewed from the right as seen in
Fig. 1;
Fig. 3 is a horizontal cross sectional view taken
approximately on the line III-III of Fig. 2‘;
Fig. 4 is a diagrammatic horizontal cross sec-. '
tional view of the entire kiln showing schemati
cally the draft conduits of the several furnaces;
Fig. 5 is a vertical cross sectional view taken;
through the master control valve for the forced‘
draft;
.
.
Fig. 6 is a horizontal cross sectional view taken
on the line VI-VI of Fig. 5; and
'
Fig. 7 is a valve diagram showing one complete
cycle of operation of the drafts for the several
related furnaces of the lime kiln of Figs. 1 -
through 4;
Figure 8 comprises an enlargement of the por
tion of the linkage appearing at the upper right
hand corner of Figure 1.
Throughout the several ?gures of the draw- ~
ings like characters of reference denote like parts
and the numeral l0 designates a conventional
lime kiln of the type comprising a vertical tower
wherein the limestone charge is fed into the top
of the kiln (not shown) and the calcined lime
(calcium oxide), is removed at the bottom of
the kiln, likewise not shown in the drawings.
The present invention deals primarily with the
means for ?ring the kiln which in the illustrated
instance resides in the provision of a plurality
of furnaces disposed about the kiln toward the
bottom thereof and consequently only that por
tion of the kiln tower is illustrated. The kiln
4
stance a flap 26 in the illustrated form. In pro
ceeding in accordance with the present inven
tion it is further desired to provide for the in
troduction of natural draft over the ?re and
to this end the illustrated embodiment is pro
vided with a pair of sliding valves or gates 2|
for each furnace unit. The natural draft valves
‘is and 2| are arranged for automatic operation
in a manner which will presently appear.
In addition to the natural draft valves referred
to each furnace unit is provided with a pair of
' forced draft ducts, one above and one below the
In Fig. 2 the numeral 23 des
ignates a forced draft duct below the grate and
the numeral 26. designates a forced draft duct
leading into the combustion chamber above the
?re. The disposition and direction of the ducts
23 and 2!; appear further in the composite cross
sectional view, Fig. 3 of the drawings, as directed
obliquely toward the vertical center line of the
‘ ?re in each case.
ash pit and the combustion chamber respec
tively. Each of the forced draft ducts 23 and
24 are provided with control valves and such
valves, in the form of sliding plates, are desig
nated 2'! and 28 respectively.
Suitable mechanical instrumentalities
and
drive means are provided for opening and clos
ing the several natural and forced draft valves
in a particular sequence and for directing pres
sure blasts into the several combustion chambers
and ash pits at predetermined related times in
the course of operation of my improved lime
kiln. Such mechanical means may be varied
from those here shown without affecting the prin
ciples of my invention and at this point in the
description of a single exemplary embodiment of
my invention I shall describe the functional se
quence of operation of the several valves and
the pressure blasts without reference to the me
charging and discharging means may be selected
from such means as are presently known for these 40 chanical means for producing and controlling
such functional sequence.
purposes without affecting the application of the
principles of my present invention to an other
wise conventional lime kiln.
In the present instance there are four furnaces
associated with the kiln tower H] and for con
venience of reference these furnaces have been
numbered I through 4 as shown in the diagram
matic view, Fig. 4. These furnaces have been
shown as being of the conventional dutch» oven
type excepting insofar as their novel shaft ar
rangement and operation are concerned.
In Fig. 1 furnace No. l is shown in vertical
cross section and furnace No. 3 appears in ele
vation. In the ensuing discussion correspond
ing parts of the several furnaces and their ap
purtenances will be given like characters of ref
erence, regardless of the fact that some of those
parts are in different positions in their cycle of
operation on the different furnaces at any given
time.
In the form illustrated each furnace comprises
a casing l2 which may comprise a ?xed part of
Reference is had to the composite valve dia
gram which is Fig. 7‘ and which shows the timed
relationship of the draft valves and pressurq
blasts of the four furnaces which are included
in the present illustrative embodiment of the in
vention. It is to be noted that the several fur
naces all discharge their gaseous products of
combustion into the single kiln tower ID at sub
stantially the same level but at points spaced
about such tower and an object of the arrange
ment of the present invention resides in so cor
relating the operation of the several furnaces
as to produce a uniform application of heat to
the charge in the kiln to produce satisfactory
calcination thereof as set forth in the remarks
preliminary to the description of the present
speci?c example.
The valve diagram, Fig. 7, shows a single com
plete cycle of operation of vthe four interrelated
furnaces, and such cycle is represented as com
prising 360°. At the conclusion of the cycle
shown, the several draft valves and the forced
the structure of the kiln tower Ill. Within each
draft apparatus all are in the same condition
furnace casing it there is provided a grate l3 with
and position in which they were at the beginning
a conventional combustion chamber l4 above the
of such cycle.
grate and a conventonal ash pit l5 therebelow.
Reference will ?rst be had to the cycle of op
A pair of fines is conduct the gaseous products
eration of a single furnace and for this purpose
of combustion from each furnace into the in
reference will be had to furnace No. I. It is not
terior of the tower H] where they come into con
ed that the cycles of the several furnaces are
tact with the charge of limestone or other ma
identical in their details excepting only for the
terial to be calcined.
fact that they are stepped as to phase of oper
Each furnace unit, as appears best in Fig. 2,
ation.
is provided with a conventional ?re door It and
At the beginning of a complete cycle of opera
an ash pit door 19. The ash pit door l9. may be
provided with a natural draft valve as for in 75 tion, the lower forced draft valve 21 of furnace
5
21,409,206
No. I has just opened and the upper forced draft ,
valve 28 has just closed. At the same time the
lower natural draft valve 20 has just closed and
the upper natural draft valves 2! have just
opened.
This condition, in which the lower forced draft
valve 27 and the upper natural draft valves 2!
are open and the lower natural draft valve and
the upper forced draft valve are closed, is indi
cated in the valve diagram by horizontal lining,
and it will be noted that this condition prevails,
in the case of furnace No. I, from the beginning
of the cycle to a point half way through. At this
latter point the conditions of the several valves
of this furnace reverse; that is, the lower nat~
ural draft valves 29 and the upper forced draft
valves 28 open and the‘ lower vforced draft‘ valves
‘5' and the upper natural draft valves 2| close.
This condition of the valves is indicated by ver
tical lining in Fig. 7 and it is noted that such
condition prevails throughout the last half of
the complete cycle in the case of furnace No. I.
6
to move the products of combustion into thekiln.
Again to prevent the escape or diversion of the
forced blast, the upper natural draft valvesare
closed at this time.
'
‘ ’ V-
J
The pulsating or surging action so'pmduced
has the effect of causing the hot gases‘ and the
flame to whirl and surge through the mass of
limestone in the kiln and is found to avoid
channeling and pocketing of the heat in -a
hitherto unattainable manner. The draft cycle
hereinbefore disclosed is further found to be un
usually e?icacious in forcing the carbon dioxide
gases evolved in calcination to the thrown off
from the limestone and out of the top of the kiln.
The operation of each of the three remaining
furnaces is identical with that of furnace No. 7|
with two exceptions only. The ?rst is unimpor
tant and resides in the fact that the forced’ draft
blasts indicated by the’ ‘braces in Fig. 7 vary
slightly asto their time of occurrence in the sev
eral instances. This is merely a question of ex
pedience in’ arranging the valve control mecha
nism and may be dispensed with by employing
While the mere opening of either the lower or
upper natural draft valves 25] and 2|, respectively,
a somewhat more elaborate valving arrangement.
is self-sufficient to give access to draft air, the
The second difference as between the several
mere opening of either the lower or upper forced
furnaces is one which further promotes uni
draft valves 27 and 28, respectively, is merely a
formity in the application of the hot gaseous
condition precedent to the actual application of
products
of combustion about the kiln, and fur
a forced blast of draft air. Such blast of draft
ther
augments
surging and whirling action
air is, in the present instance, of relatively short 30 of‘such gases tothefurther
enhance the efficiency
duration and it is only required that the forced
and uniformity of operation of my new kiln.
blast be applied to the duct 23 for a brief period
Each of the furnaces from I through 4 is
during the 180° portion of the cycle that the
90° behind the vpreceding furnace in phase? so
lower forced draft valve 21 is open, and, fur
that the peak discharges of hot gaseous products
ther, that a second forced draft blast be applied
from the several furnaces follow each other at
to the upper forced draft duct 24 for a brief pe
regularly
timed intervals. It is believed that this
riod during the 180° interval when the upper
recurring
phase relationship is clearly evident
forced draft valve 28 is open. ‘
,
from a consideration of the valve diagram, Fig. '7.
Only a single forced draft’ source is utilized
Reference will now be had to a master control
in the apparatus which forms the present illus
valve
means for producing appropriately timed
tration and that single source is variously di
blast impulses directed successively to the several
verted during the complete cycle of operation by
furnaces. Such means is illustrated in detail in
suitable valve mechanism which will presently
Figs. 5 and 6 and schematically at 3| in Fig. 4.
be described. The braces which extend from the
Reference has previously been had to a com
45° to the 90° point in the case of furnace No. I, 45 mon forced blast duct 38 which supplies the lower
and likewise from the 225° to the 270° point, in
and upper forced draft ducts 23 and 24 of fur
dicate that during these two different 45° inter
nace
No. I. A similar common blast supply duct
vals, forced draft is applied.
_
32 is provided for the upper and lower forced
The ducts 23 and 24 are branches of a com
blast ducts of furnace No. 2, and similar ducts
mon supply duct 33 which is indicated schemat 50 33
and 34 perform a like function for furnaces
ically in Fig. 4. By virtue of this arrangement it
Nos. 3 and 4 respectively.
'
is only necessary for the master controlling valve
mechanism, indicated schematically at 3!, to cli
Referring to the diagrammatic showing of Fig.
4, the numeral 37 designates a blower or other
vert pressure blasts to the four furnaces by
suitable air pressure generator means adapted to
means of four discharge ducts, one for each fur 55 be driven by a motor 38 or the like. The blower
nace. The ultimate diversion of such forced
draws its air from heat exchange coils 39 ar
blast to either the ash pit or the combustion
ranged adjacent the exteriors of the several fur
chamber of the furnace is controlled solely by the
naces whereby the forced blast air is pre-heated
forced draft valves 21 and 28 at the furnace. It
to some extent. The blower directs its output air
is sufficient for the present to state that the
60 to a cylindrical casing 40, which forms the main
master valve mechanism 3! is arranged in such
chamber of the master control valve means desig
manner that it directs two forced blasts into the
nated generally at 3i, by means of a conduit 4|
duct 3i! directed to furnace No. l during each
which discharges into the casing 49. An end wall
complete cycle of operation and these two blasts
42 of the casing 40 has four ports spaced equally
occur as indicated by the braces in the valve di~
65 about a common circle struck from the center of
agram.
the end wall 42 and one each of these ports com
The practical result of this draft valve cycle is
municates with each of the ducts 3!], 32, 33 and
that a blast of air is forced under the grate, with
34, which lead to furnaces Nos. I through 4, re
the natural draft valve for the ash pit in a closed
spectively.
condition to prevent the escape of air, and to 70
A rotatable valve plate 43 is disposed against
force such blast through the fuel bed. At the
the inside of the end wall 42 and is provided with
same time the upper natural draft valve is open
an arcuate port 45 which lies along an arc co
to admit additional draft air above the fuel bed.
incident with the circle about which the ports
‘Following this, the lower natural draft valve
opens and a forced blast is-forced overthe ?re
leading to the ducts 30, 32, 33, 34 are spaced. The
valve plate 43 serves to close all of the duct pas
214091206
sages excepting the one which happens to be in
registry with the port 45 of the valve plate.
By rotation of the valve plate 43 the ducts 30,
32, 33 and 34 are successively placed in com
munication with the interior of the casing 43
and thereby with the supply duct 4|. Since two
pressure blasts are desired to be delivered to each
furnace during a 360° cycle of operation, the valve
plate 43 is arranged to rotate twice during each
such cycle. Rotational impulses are delivered
thereto by means of a central shaft 41 extending
through and journaled in a cylindrical casing 40
and bevel gears 48 which connect the valve shaft
41 with a drive shaft 49.
The sequence in which the ducts for the four
furnaces receive blasts from the casing 49 by
rotation of the valve plate 43 is as follows. First,
furnace No. I; second, furnace No. 3; third, fur
nace No. 2; and fourth, furnace No. 4. The
manner in which this sequence of blasts ties in
with the sequential operation of the four furnaces
will be clear from a study of Fig. 7 and particu
larly the braces in that ?gure which indicate the
application of pressure blasts.
Any convenient means for opening and closing
the various forced and natural draft passages
may be availed of as long as the operation of such
means results in timing of the opening and clos
ing movements in accordance with the principles
laid down in the foregoing discussion.
As one
example of suitable valve opening and closing
means I have shown associated with each fur
nace a rock shaft 50 adapted to be oscillated and,
by suitable connection to the several valves, to
transmit such oscillations to the latter to open
and close the same in opposite directions of oscil
lation. The rock shaft 55 may be journaled in
bearings 5| secured against the front wall of each
natural draft valve 20 likewise is controlled by a
rock arm 52 carried by the shaft 50‘, but in this
instance an intermediate rock shaft 63 is jour
naled against the front of the furnace and has a
rock arm 64 which is connected with the arm 62
by a chain 65 or the like for receiving its rocking
impulses. The intermediate rock shaft 63 has
a second rock arm 61 which engages one end of a
link 68 whose other end is pivotally connected to
the draft valve 20 to raise and lower the same
about its upper hinged connection. This indi
rect connection between the rock arm 62 and the
draft valve 20 is provided merely to avoid inter
ference with the door |8 leading to the combus
tion chamber.
It will be noted that the rock arms 60 and the
rock arms '62 extend in opposite directions from
the shaft 50 so that movement of one of them to
close its associated natural draft valve is ac
companied by movement of the other rock shaft
to open its associated natural draft valve.
Each rock shaft 55 is also provided with a rock
arm 19 which is connected with both the upper
and lower forced draft valves 28 and 21, respec
tively, by chains 1|, ‘E2 or the like. rI‘he valves
21 and 28 are accordingly arrangedv to move up
wardly and downwardly in unison with the upper
natural draft valves 2|. It will be noted, how
ever, that the lower forced draft valve 2‘! is closed
by downward movement and opened by upward
movement while the reverse is true in thecase of
the upper forced draft valve 28. For this reason
closing movement of the upper natural draft
valves 2| is accompanied by opening movement
of the upper forced draft valve 28 and closing
movement of the lower forced draft valve 21.
It will, of course, be understood that the rock
ing impulses transmitted to the rock shaft 50
of each of the four furnaces by means of a crank
furnace and each rock shaft 5|] is caused to oscil
55, link 5'! and rock arm 55, will be 90° behind in
late by connection with a continuously rotating 40 operation with respect to the preceding furnace,
shaft 53 which, in the present instance, is car
having in mind the valve diagram, Fig. '7, and the
ried in bearings secured against the tops of the
successive operations there indicated.
several furnaces.
In the present instance a single shaft 53 at
each side of the kiln serves to oscillate the pair of
rock shafts 59 for the two furnaces at that side
of the kiln. Each rock shaft 50 has a relatively
short driving arm 55 which has connection with
To produce‘ the same relative direction of rota
tion at opposite sides of the kiln the shaft 53 for
furnaces Nos. |- and 2, and the shaft 53 for fur
naces Nos. 3 and 4, must rotate in opposite direc
tions, and such opposite rotation may convenient
ly be attained by providing a pair of intermediate
shafts 80 extending coaxially and at right angles
51. Connection between the link 51 and the driv in) to the shaft 53. The shafts 85 each engage a
ing arm 55 of the rock shaft 59 is by means of an
shaft 53 by virtue of a beveled gear connection
elongate slot 58 in the link engaged by a pin 59
8|, and a common bevel driving gear 82 carried
carried by the outer end of the arm 55. In this
by a drive shaft 83 engages a pair of bevel gears
way, while the crank 56 rotates continuously, it
84, one on each of the shafts 80, to rotate the
transmits rocking movement in opposite direc- ; two shafts 85' in opposite directions.
tions to the driving arm 55 intermittently; name
Attention has previously been called to the
ly, only when an end of the slot engages the'driv
fact that the master control valve 43 is desired
ing arm pin. By virtue of this construction the
to be driven at twice the angular velocity of the
opening and closing of the several valves at the
shafts 53 which control the draft valves for the
furnace by oscillation of the rock shaft is local to individual furnaces. This ratio may be estab
a crank 56 on the shaft 53 by means of a link
ized so as to occur in a fairly brief changeover
period.
The connections between the four rock shafts
50 and their associated furnaces are the same
in the case of the several furnaces and conse
lished in any convenient manner and I have in
dicated schematically in Fig. 4 a speed reducing
unit 88 which is caused to rotate both shafts 49
and 83, for the master valve and the individual
furnace valves, respectively, by means of a driv
ing motor 89 or the like.
While variations in the speed of operation of
quently, reference will be had by way of example
only to furnace No. I, which appears at the right
hand portion of Figs. 1, 2 and 3, respectively.
my improved pulsating draft arrangement may
An enlargement of the portion of the linkage ap
be made without departing from the teachings
pearing at the upper right hand corner of Figure 70
hereof, I have found that operation of the appa
1 is shown in Figure 8.
In the case of furnace No. |, a, pair of rock
arms 30 are carried by the shaft 59 and connected
at their outer ends with the upper natural draft
ratus in such manner as to produce thirty-two
blast impulses per minute, eight at each furnace,
four above and four below the grate, operates
in
a highly satisfactory manner,
valves 2| by chains or‘ the like, 6|. The lower 75
9,4.09a'206
What is claimed is:
.
_
1. calcining apparatus comprising a charge re~
ceiving chamber, a furnace associated therewith,
10
chamber above the grate and an ash pit there
below, a conduit between said combustion cham
ber and said charge receiving chamber whereby
a grate in said furnace with a combustion cham
gaseous products of combustion from said come
ber above the grate and an ash pit therebelow,
bustion chamber may be discharged into said
a. conduit between said combustion chamber and
charge chamber, a natural draft valve for said
said charge receiving chamber whereby gaseous
ash pit, automatic means for opening and closing
products of combustion from said combustion
said
natural draft valve in substantially continu
chamber may be discharged into said charge
ously recurring succession, meansfor directing
chamber, draft means associated with said ash 10 forced blasts of air into said ash pit, and means
pit and other draft means associated directly with
for timing such blasts to occur during periods
said combustion chamber, and automatic means
.when said natural draft valve is closed.
for rendering both draft means intermittently
operative in substantially continuously recurring
succession.
-
a
2. Calcining apparatus comprising a charge
receiving chamber, a. furnace associated there
with, a grate in said furnace with a combustion
chamber above the grate and an ash pit there
6. Calcining apparatus comprising a charge re
ceiving chamber a furnace associated therewith,
15 a grate in said furnace with a combustion cham-_
ber above the grate and an ash pit therebelow,
a conduit between said combustion chamber and
said charge receiving chamber whereby gaseous
products of combustion from said combustion
chamber may be discharged into said charge
ber and said charge receiving chamber whereby
chamber,
a natural draft valve communicating
gaseous products of combustion from said com
directly with said combustion chamber, auto
bustion chamber may be discharged into said
matic means for. opening and closing said nat¢
charge chamber, draft means associated with
said ash pit and other draft means associated 25 ural draft valve in substantially continuously re
curring succession, means for directing forced
directly with said combustion chamber, and auto
blasts of air into said combustion chamber, and
matic means for alternately rendering said ash
means for timing such blasts to occur during-pe
pit draft means operative and inoperative in sub
riods when said natural draft valve‘ is closed.
stantially continuously recurring succession and
for simultaneously rendering the combustion 30 7. Calcining apparatus comprising a charge re
ceiving chamber, a furnace associated therewith,
chamber draft means operative when the ash
below, a conduit between said combustion cham
pit draft means is inoperative and vice versa.
3. Calcining apparatus comprising a charge re,
ceiving chamber, a furnace associated therewith,
a grate in said furnace with a combustion cham»
ber above the grate and an ash pit therebelow,‘
a conduit between said combustion chamberand
said charge receiving chamber whereby gaseous
products of combustion from said combustion
chamber may be discharged into said charge
chamber, forced draft means associated with said
ash pit and other forced draft means associated
directly with said combustion chamber, a natural
draft valve for said ash pit and a second natural
draft valve for said combustion chamber, and
automatic operating means whereby the natural
draft valves are opened and closed successively,
the natural draft valve for the combustion cham~
ber being closed when the natural draft valve
for the ash pit is open and vice versa, and means
a grate in said furnace with a combustion cham-I
ber above the grate and an ash pitthereb'elow,
a conduit between said combustion chamber. and
said charge receiving chamber whereby gaseous
products of combustion from said combustion
chamber may be discharged into said charge
chamber, forced. draft means associated ._with
said ash pit and other forced draft means ‘asso
ciated with said combustion chamber, and auto
matic control means for both of said forced draft
means for alternately directing forced blasts of
draft air to said ash pit and to said combustion
chamber in substantially continuously recurring
succession, the combustion chamber draft means
being arranged to direct the forced blast'over a
fuel bed and. toward the conduit leading tothe
charge receiving chamber.
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a
;
i
8. Calcining apparatus comprising a charge re»
ceiving chamber, a furnace associated therewith,
for directing forced draft to said ash pit forced ‘
a, grate in said furnace with a combustion cham
draft means while the ash pit natural draft valve
is closed and for directing forced draft to said
combustion chamber forced draft means while
the combustion chamber natural draft valve is
ber above the grate and an ash pit therebelow,
a conduit between said combustion chamber and
said charge receiving chamber whereby gaseous
products of combustion from said combustion
chamber may be. discharged into said charge
chamber, a. natural draft valve associatedv with
closed.
4. Calcining apparatus comprising a charge re
ceiving chamber, a furnace associated therewith,
said ash pit and a second natural draft valve asso
a grate in said furnace with a combustioncham
conduit between said combustion chamber and
ciated directly with said combustion chamber, au~
tomatic means for simultaneously opening one of
said valves and closing the other in substantially
said charge receiving chamber whereby gaseous
continuously recurring succession.
products of combustion from said combustion
chamber may be discharged into said charge
chamber, forced draft means associated with said
ash pit and other forced draft means associated
directly with said combustion chamber, and au
tomatic control means for both of said forced
draft means for alternately directing forced
blasts of draft air to said ash pit and to said 70
9. Calcining apparatus comprising a chargevre
ceiving chamber, a plurality of furnaces associ
ber above the grate and an ash pit therebelow, a
combustion chamber in substantially continu~'
ously recurring succession.
5. C‘alcining apparatus comprising a charge
receiving chamber, a furnace associated there
--
' l
ated therewith each having a grate with a- corn
bustion chamber thereabove and an ash pit theres
below, a conduit between each furnace combus
tion chamber and said charge receiving chamber
whereby the gaseous products of combustionfrom
saidi'furnaces‘are discharged into said' charge
chamber, each furnace having draft means asso
ciated with the ash pit thereof and other draft
means associated directly with its combustion
chamber, the draft means of each furnace being
with, a grate in said furnace with a combustion 75 adapted to be rendered intermittently operative
2,409,200
11
in substantially continuously recurring succes
sion, and means synchronizing the draft means
operation of the severalf-urnaces, whereby to op
erate successively in a continuously recurring
cycle.
‘
10. Calcining apparatus comprising a charge
receiving chamber, a plurality of furnaces asso
ciated therewith each having a grate with a com
bustion chamber thereabove and an ash pit there,
below, a, conduit between each furnace combus
tion chamber and said charge receiving chamber
whereby the gaseous products of combustion
12
receiving chamber, a plurality of furnaces asso
ciated therewith each having a grate with a com
bustion chamber thereabove and an ash pit
therebelow, a conduit between each furnace com
bustion chamber and said charge receiving cham
ber whereby the gaseous products of combustion
from said furnaces are discharged into said
charge chamber, each furnace having associated
therewith means for intermittently applying a
forced blast of draft air to its ash pit, and means
synchronizing said forced blast means whereby
the forcedv blasts of the several furnaces occur
successively in a continuously recurring cycle.
from said furnaces are discharged into said
15. Calcining apparatus comprising a charge
charge chamber, each furnace having draft
15 receiving chamber, a vplurality of furnaces asso
means associated with its ash pit and other draft
ciated therewith each having a grate with a com
means associated directly with its combustion
bustion chamber thereabove and an ash pit
chamber, means associated with each furnace for
therebelow, a conduit between each furnace com
alternately rendering the ash pit draft means op
bustion chamber and said charge receiving cham
erative and inoperative in substantially continu
20 ber whereby the gaseous products of combustion
ously recurring succession and for simultaneously
from said furnaces are discharged into said
rendering the combustion chamber draft means
charge chamber, forced draft means associated
operative when the ash pit draft means is inop
with the ash pit of each furnace and other forced
erative, and vice versa, and means synchronizing
draft means associated directly with its combus
the draft means of the several furnaces whereby 25 tion chamber, a natural draft valve for the ash
they operate successively in a continuously re
pit of each furnace and a second natural draft
curring cycle.
valve for its combustion chamber, operating
11. Calcining apparatus comprising a charge
means whereby the natural draft valves are
receiving chamber, a plurality of furnaces asso
opened and closed successively, the natural draft
ciated therewith each having a grate with a com 30 valve for the combustion chamber being closed
bustion chamber thereabove and an ash pit
when the natural draft valve for the ash pit is
therebelow, a conduit between each furnace com
open, and vice versa, means for directing forced
bustion chamber and said charge receiving cham
draft to the ash pit forced draft means of each
ber whereby the gaseous products of combustion
furnace while its ash pit natural draft valve is
from said furnacesv are discharged into said 35 closed and for directing forced draft to its com
charge chamber, forced draft means associated
bustion chamber forced draft means while its
with the ash pit of each furnace and other forced
combustion chamber natural draft valve is
draft means associated directly with its combus
closed, and means synchronizing the operating
tion chamber, control means for both of the
means of each furnace to operate the draft mech
forced draft means of each furnace for alter 40 anisms of the several furnaces so that their like
nately directing forced blasts of draft air to its
phases of operation are stepped uniformly to
ash pit and to its combustion chamber in re
occur successively at regular intervals in a con
curring succession, and means synchronizing the
control means for the several furnaces whereby
the phases of draft operation of the several fur
naces are stepped uniformly to follow each other
in continuously recurring succession.
12. Calcining apparatus comprising a charge
receiving chamber, a plurality of furnaces asso
ciated therewith eachhaving a grate with a com
bustion chamber thereabove and an ashgupit
therebelow, a conduit between each furnace'com
bustion chamber and said charge receiving cham
ber whereby the gaseous products of ‘combustion
tinuously recurring cycle.
16. A method of calcining material in a kiln
45 having associated therewith a furnace arranged
to discharge its gaseous products of combustion
into said kiln and comprising a combustion cham
ber, a fuel bed supporting grate and an ash pit;
said method comprising successively and alter
50 nately directing forced blasts of air into said ash
pit and into said combustion chamber respectively.
17. A method of calcining material in a kiln
having associated therewith a furnace arranged
to discharge its gaseous products of combustion
from, said furnaces are discharged into‘ said
into said kiln, and comprising a combustion
charge chamber, each furnace having associated
therewith means for intermittently applying
thereto a forced blast of draft air, and means
synchronizing the forced blasts of the several fur
chamber, a fuel bed supporting grate, and an
naces whereby they occur successively.
ash pit; said method comprising ?rst, directing
a blast of air into said ash pit, then directing a
blast. of air into said combustion chamber above
the fuel bed and. in the direction of discharge of
13. Calcining apparatus comprising a charge 60 gaseous products into said kiln, and successively
receiving chamber, a plurality of furnaces asso
repeating such sequence of blasts.
ciated therewith each having a grate with a com
18. A method of calcining material in a kiln
bustion chamber thereabove and an ash pit
having associated therewith a furnace arranged
therebelow, a conduit between each furnace com
to discharge its gaseous products of combustion
bustion chamber and said charge receiving cham 65 into said kilnand comprising a combustion cham
ber whereby‘ the gaseous products of combustion
her. a fuel bed supporting grade and an ash pit;
from said furnaces are discharged into said
said method comprising successively and alter
nately directing forced blasts of air into said ash
therewith means for intermittently directing a
pit and into said combustion chamber respectively
forced blast of’ air over the fuel bed and toward 70 at a frequency of the order of one or more cycles
charge chamber, each furnace having associated
its charge chamber conduit, and means synchro
per minute.
nizing the forced blasts of the several furnaces
19,. A method. of calcining material in a kiln
whereby they occur successively with respect to
having associated therewith a furnace arranged
each other.
to discharge its gaseous products of combustion
14. Calcining apparatus comprising a charge 75
13
2,409,206
into said kiln and comprising a combustion
chamber, a fuel bed supporting grate, and an ash
14
equally spaced intervals throughout a full cycle
of operation.
21. A method of calcining material in a kiln
having associated therewith a plurality of fur
naces arranged to discharge their gaseous prod
pit; said method comprising ?rst directing a blast
of air into said ash pit, then directing a blast
of air into said combustion chamber above the
fuel bed and in the direction of discharge of
gaseous products into said kiln, and successively
repeating such sequence of blasts at a frequency
ucts of combustion into said kiln and each com
prising a combustion chamber, a fuel bed sup
porting grate and an ash pit; said method com
of the order of one or more cycles per minute.
prising successively and alternately directing
20. A method of calcining material in a kiln 10 forced blasts of air into the ash pit and into the
having associated therewith a plurality of fur
combustion chamber respectively of each furnace,
naces arranged to discharge their gaseous prod
the combustion chamber forced blast being ef
ucts of combustion into said kiln and each com
prising a combustion chamber, a fuel bed sup
porting grate and an ash pit; said method com
prising successively and alternately directing
fected above the fuel bed and in the direction of
discharge of gaseous products into said kiln, and
15 timing the application of such pair of forced
blasts to each furnace to occur successively at
forced blasts of air into the ash pit and into the
equally spaced intervals throughout a full cycle
combustion chamber respectively of each furnace
of operation.
and timing the application of such pair of forced
'
WILLIAM E. HESSMAN.
blasts to each furnace to occur successively at 20
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