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Патент USA US3074717

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Jan. 22, 1963
J. J. HUMPHRIES ETA;
3,074,707
PRocEss FOR THE MANUFACTURE oF CEMENT
Filed Aprii 15, 1960
6 Sheets-Sheet 1
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_ Jan. 22, 1963
J.'J. HUMPHRIES ET AL
3,074,707
PROCESS FOR THE MANUFACTURE OF CEMENT
Filed April 15, 1960
6 SheetSFSheet 2
Jan» 22, 1953
J. J. HUMPHRlEs ETA;
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3,074,707
PRocEss FOR THE MANUFACTUEE oF CEMENT
Filed April 15, 1960
6 Sheets-Sheet 5
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INVENTORS
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Jan. 22, 1963 -
3,074,707
J. J'. HUMPHRlES ETAL
PROCESS FOR THE MANUFACTURE OF CEMENT
6 Sheets-Sheet 4
Filed April 15, 1960
FI/G. 6
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OXYGEN ADDED IN CFM
Jan. 22, 1963
3,074,707
J. J. HUMPHRIES ET AL
PROCESS FOR THE MANUFACTURE 0F CEMENT
Filed April 15,v 1960
6 Sheets-Sheet 5
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Jan. 22, 1963
3,074,707
J. J. HuMPHRlEs ETA:
PRocEss FOR THE MANUFACTURE oF CEMENT
Filed April 15, 1960
20X
6 Sheets-Shee‘l'l 6
F/G. 8
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3,074,7ti'7
PROCESS FOR THE MANUFACTURE OF «CEMENT
Jantes J. Humphries, Chatham, and Abram L. Hodge,
Cranford, NJ., Roger S. Babcock, Berwyn, Fa., and
Bruce C. Whitmore, Downsvievv, Ontario, Canada, as
signors to Union @arbide Corporation, a corporation of
New York
Filed Apr. 15, 1960, Ser. No. 22,424
S Claims. (Cl. 263--53}
3,0?41-,707
Patented Jan. 22, i953
2
a temperature of below at least 1450*o F. wherein low
grad@ energy is supplied to the raw materials; supplying
an oxygen stream to the kiln from the discharge end and
positioning such oxygen stream between the llame and
the cement-forming raw material in the kiln at a point
within the area, in a plane transverse to the axis of
the kiln, defined by the center of the llame and the ex
tremities of the raw material load and preferably at a
point on a line drawn from the center of the llame to the
center of the mass of such raw materials thereby causing
or similar materials and more particularly to an im
>an increase of energy in the high grade energy zone and
a decrease of energy in the low grade energy zone with
proved method for burning cement-forming raw mate
rials in a rotary kiln.
The cement making process is essentially a combus
to absorb the increase of high grade energy available
This invention relates to the manufacture of cements
tion process wherein a cement-forming raw material
mixture consisting of calcareous material usually lime
stone (CaCO3) and argillaceous materials such as clay,
shale, etc., containing alumina (A1203), silica (SiO2)
out changing the total energy available, and then in
creasing the feed rate of the raw materials to the kiln
such that a condition of substantial thermal balance
is established in the kiln.
Other objects and features of novelty of the invention
will be specifically pointed out or will become apparent
and some iron oxide (Fe2O3) in the proper proportions 20 when referring, for a better understanding of the in
vention, to the following description in conjunction with
is heated, usually by an air-fuel llame, to a temperature
of about 1450“ F. or above at which the limestone
the accompanying drawings wherein:
(CaCO3) Will Ibreak down into lime (CaO) and carbon
ydioxide (CO2). The lime, silica, alumina and iron
FIG. 1 is a longitudinal section view of a rotary kiln
showing the relative position of the llame and oxygen
cement, none of these eñorts have resulted in a com
the invention and for ordinary oxygen firing;
oxide is then further heated to a temperature in the 25 stream therein;
FIG. 2 is a partial broken transverse section of the
range of from about 2400 to 2800“ F. at which tempera
kiln showing the position of the oxygen stream in this
ture the material will begin to liquefy a-nd absorb a por
plane;
tion of the other components. This semi-liquid state
FIGS. 3a, 3b, and 3c are illustrations of thermal
agglomeration is called clinker.
gradients
respectively, of a normal kiln flame, an ordinary
30
Oxygen has been used in the steel industry for enrich
oxygen enriched flame, and of a flame with an oxygen~
ing air supplies to open hearth furnaces for many years.
ated zone provided according to the invention;
The results in that industry have been remarkable. In
FIG. 4 is a curve of refractory and solid thermal
fact, today almost all steel manufacturers utilize oxygen
gradients with air tiring and with oxygen ñring;
enrichment in their steel making processes.
FIG. 5 is a curve showing relationship of kiln rota
Although there have been indications in the prior art
tion to temperature for firing a furnace according to
of early attempts to utilize oxygen in the production of
mercially feasible process.
One of the major drawbacks attendant to the use of
oxygen was the overheating and rapid deterioration of 40
the refractory linings in the rotary kilns. Attempts have
been made to shield the refractories from the intense heat
of the oxygen enriched llame but all have resulted in
excessive waste of valuable heat energy.
Another drawback has been an economical one. The
cement industry producing a low market value product
has always had the impression that cost of installing
oxygen equipment would be prohibitive relative to the
selling price of cement.
Accordingly, it is an object of this invention to provide
a method for making cement wherein oxygen is utilized
to enrich the air-fuel llame in a rotary kiln which elimi
nates the above-mentioned drawbacks heretofore associ
ated with the use of oxygen and to provide an economi
FIG. 6 is a curve of feed end temperature vs. oxygen
addition;
FIG. 7 illustrates the increase in production with oxy
gen additions according to the invention; and
FIG. 8 represents a curve of feed end velocity vs.
oxygen enrichment.
For the purpose of describing the method of the in
vention the following description refers specifically to
the manufacture of Portland cement by the heat process.
This is not to be understoo-d as limiting the invention in
any way except as limited and deñned by the appended
claims.
Portland cement is made by mixing and calcining
calcareous and argillaceous materials in the proper pro
portions. There are two main processes in current use;
namely, the wet process and the dry process. The wet
process involves the grinding and mixing of the raw
cally feasible cement-making oxygen process.
materials in slurry form. On the other hand, the dry
Another object is to provide a method for making
cement wherein oxygen is used to redistribute the energy
process involves drying and crushing the raw material
and subsequently blending them in the dry state. In both
available in a cement kiln.
processes the raw materials are then fed to a rotary kiln.
The kiln is fired at the feed discharge end through
An additional object is to provide a method of utiliz
ing oxygen in a cement-making process which results in 60 a stationary hood with air and fuel such as oil, powdered
coal or gas. This end is at an intense heat of at least
au increase in production and a reduction in fuel con
about 1450" F. and provides a zone wherein what is
sumption and dust per barrel of product manufactured.
known as high grade thermal energy is supplied to the
The foregoing objects are achieved in the process
solids. As' the hot gases of combustion sweep through
of the invention which in its .broadest aspects comprises
lcharging cement-forming raw materials a-t a certain feed 65 the kiln, they are cooled by the raw material that is bn
ing dried and calcined and escape at the feed inlet end
rate to the feed end of a rotary kiln, injecting a combusti
of the kiln at temperature sufliciently in excess of the
ble mixture into the kiln from the discharge end thereof
dew po-int of -the gases to prevent condensation of water
and igniting the mixture to provide a flame in the kiln;
vapor in associated gas cleaning equipment or in the
such llame establishing within the kiln a high grade en
kiln itself. Enegry which is supplied to the raw ma
ergy zone at a temperature of about at least l450° F.
terials inthis cooler zone of the kiln below the nominal
wherein high grade energy is supplied to the cement-form
minimum calcination temperature of l480° F. is con
ing raw materials and also a low grade energy zone at
3,074,707
3%
sidered low grade energy. The product formed in the
kiln is a hard granular mass called clinker. This clinker
at a temperature in the range of from about 2400“ F. to
2300" F. and usually about 2500" F. passes into a cooler
which serves to preheat air entering the combustion
always an excess of lower grade energy. The shift in
energy caused by oxygen additions reduces the heat
available at the exhaust gas end of the kiln. It steps
are taken to reduce the moisture in the slurry and thus
reduce the moisture condensation problem, still greater
zone.
production increases will be realized with increased
Also the heat absorbed in cooling the clinker may
ing production is the availability ot high grade energy.
oxygen additions. Referring again to FiG. 6, it will be
noticed that it the moisture content of the slurry is re
duced to 30%, 800 Cim. of oxygen may be added to the
llame without decreasing the temperature below 240° F.
Using the data in lilG. 7, it is noted that at 800 cirn.
An examination of exit gas temperatures indicates that
Ithere is an excess of low grade energy exhausted from
production is increased by about 30 bbl.’s. @ther possi
ble solutions to the problem of decreased exhaust gas
be utilized to power associated equipment.
To make
a pound of clinker about 920 B.t.u.’s or^ high grade energy
and only about 650 B.t.u.’s of low grade energy aire re
quired.
In all cement kilns the limiting Íactor to obtain
the kiln.
temperature with increased oxygen liow rates are to pro
This invention is predicated on the discovery that a
vide a heater at the back end to keep the temperature
beneiicial change in the relative availability of the two
of gases leaving the kiln above the minimum value;
grades ot energy is realized when oxygen is added to the
to insulate the back end of the kiln; or to design a new,
combustion process according to the method hereinafter
shorter kiln.
`
described.
When oxygen is added to a kiln-cooler unit (FIG. l)
Consider, for example, a kiln firing Íuel which provides 20 high tempera-ture heat is increased in two ways. Con
`approximately 98 million B.t.u.’s of energy. in the case
sider an example wherein a kiln is burning 100 units ot
where no oxygen is added to the frame and a 35% mois-
fuel and the exhaust gas is at a temperature of 1000o F.
ture containing slurry is utilized as the feed there is
and the air necessary for combustion is preheated in
the cooler to a temperature of 500° F. In this hypo
thetical case, add 10 units of oxygen to the combustion
zone. High temperature energy will increase and the
exhaust gas temperature will decrease as discussed above.
approximately 2l million B.t.u.’s of high temperature
energy available to do work, that is, to calcine and
further heat the raw materials, in the high temperature
zone of the kiln.
ln the low temperature zone there is a ailable about
28 million B.t.u.’s for driving water from the slurry added
'ln such case more high temperature energy is available.
The feed rate of raw materials to the kiln is increased
to the kiln ras raw materials; another approximated 27
million B.t.u.’s are available to bring the raw materials
up to calcining temperature and about 25 million
to absorb the increased energy. This provides addi
tional hot product to the cooler which in turn will add
B.t.u.’s at about 680° P. are discharged in the exhaust
gas. This represents a high temperature energy utili
zation (H.T.E.U.) of about 21.5%, a low temperature
energy utilization (LÍiÍEU.) ci about 31.3% and an
exhaust gas loss of about 25.5% or a ratio of high teni-
perature energy utilization to low energy utilization plus
energy loss in the exhaust gas of about .378.
Now as
suming the same tiring rate, 98 million B.t.u.’s, and the
same 35% moisture-containing feed but with an oxygen
addition of 6000 cih., there is approximately 23 million
B.t.u.’s of high temperature energy available to do work
in the high temperature zone. In the lower tempera
ture zone there is available about 30 mill-ion B.t.u.’s
for driving water from the slurry. Another approxh
mately 28 million B.t.u.’s are available to bring the raw
materials up to calcining temperature but only about 20
million
exhaust
23.5%,
loss of
more heat to the air coming in to be preheated so that
the combustion air is now some temperature, 500° R+.
Also with the addition of l0 units of oxygen, combustion
air may be cut by 50 units. With less >air to be heated
to flame temperature, the combustion air will be heated
again to some temperature 500° F.-+i+. As the com
bustion air temperature increases the flame becomes
hotter and the product will become hotter. In order
to get maximum utilization of the increased heat ex
hausted in the product, it is possible to insert waste heat
boiler tubes in the cooler of the cement kiln and use
the resultant steam to run on oxygen plant compressor'.
This will greatly reduce the cost of operating the oxygen
plant which supplies oxygen to be consumed in the in~
ventive process.
Referring now to FlG. l, in order to practice the inven
tion, a rotating kiln l0 is provided with a cement-form
B.t.u.’s at about 560° F. are discharged in the
gas. This represents a H.T.E.U. of about
at L.T.E.U. of about 34.4% and an exhaust gas
product discharge end l2. A hopper i3 provided with a
about 20.4% or a ratio of l'lflïBU/LTEU.
material lo into the kiln l0.
mg raw material feed inlet end ll and a cement-clinker
chute i4 is mounted near the inlet end di and feeds raw
plus energy loss in exhaust gas or about .430. This last
A. discharge chute i7' is provided at the discharge end
named ratio clearly indicates that when oxygen is added
l2 of the kiln l0 to carry the discharged cement-clinker
to the iiarne, a shift in energy takes place from the low
product from the kiln to a cooler or heat exchanger 18.
temperature zone to the high temperature zone, Where
A burner 19 is mounted at the clinker discharge end
such energy will serve to increase production.
l2 and is provided with an air line 20 and a. fuel line 21.
The addition of oxygen is limited. As illustrated
A non-consumable oxygen lance 23 is mounted at the
clinker discharge end l2 below the burner i9 and at a
by the data in FiG. 6, the temperature of 'the exhaust
gas is about 560° F. at the raw material feed end of the 60 point within the area deiined by a line connecting, in a
plane transverse to the axis of the kiln 10, the three
kiln 4at an oxygen flow rate of 6000 c.f.h. (l0-0 Cim).
points which consist of the extremities A and C of the load
Also as illustrated in FIG. 6, with increased oxygen
fiow rates the exhaust gas temperature decreases. The
lo and the center point of the darne issuing from burner
minimum exhaust gas temperature that can be tolerated
.'19 (see FIG. 2). Such lance 23 is capable of longitudi
must be high enough so that the gases passing through
nal movement so that the oxygen may be injected at ap
Referring to FlG. 7, the data summarized by
proximately the point or” combustion of the combustible
mixture discharged from the burner i9.
Secondary air is preheated and supplied to the kiln
l0 by passing it through a grating 25 in the cooler .t3 and
the curve indicates that the production increase realized,
with oxygen added at the rate of 6000 cih. (100 Cim.)
plied by the hot clinker product being discharged into
associated gas cleaning equipment will not fall below
the dewpoint of the gases in the equipment. In the tore
going discussion this ternperature is assumed to be about
' 240° F.
is about 7 bblfs and that as the oxygen flow rate is
increased, production is increased. The limitation or”
lack of heat in the exhaust gas end of the kiln is a
. new problem in cement making.
H -reto‘tore there was
up to the kiln. The energy for preheating the air is sup
the cooler. The excess energy in the clínker may be then
. utilized to power auxiliary equipment such as waste heat
boiler and tie resultant steam utilized to power' an oxygen
plant compressor.
.
ï
13,07%? O7
5
In operation of manufacture of cement in accordance
with method and apparatus of the invention, cement
forming raw materials in the form of Ia_ slurry are fed into
a rotary kiln by means of a chute connected to the raw
materials storage hopper. The feed rate is controlled by
a feed cont-roller. An amount of material sufiicient to till
only a part of the cross-sectional area of the kiln is added.
As 4the materials are rotated and slid »toward the discharge
end the material tends to climb the kiln wall as
in FIG. 2. Also, the temperature of the material
vated to from about lll-50° F. to about 1550° F.
low temperature zone, which is the zone nearest
shown
is ele- »
in the
to the
feed inlet end. At this point decomposition Iof the lime
stone begins. The temperatures of the calcined materials
are further increased in the high temperature zone-to a
flame and the load will shield the refractory from the “hot
spot” created by the .addition of oxygen. FIG. 5 com
pares the inventive method of adding oxygen to a hap
hazard addition of oxygen and the offset each has on
rotational speed. In this latter ñgure line a-a' rep
resents an increased load solids temperature. The curve
d--d’--d" is the same as in FIG. 4. The curve d---f--~ "
represents the temperature curve produced by the inven
tive, method. In the last-named method the maximum re
fractory temperature b’ is reached at point Z. Comparing
this Ito point Y for the curve for random addition of
oxygen, it readily can be seen that the increase in rota
tional speed necessary to protect the refractory in the
kiln is substantially reduced by the invention.
Another major advantage of oxygen usage in a cement
making kiln Ais the reduction of dust loss. Dust loss of a
temperature of about 2400“ F. to 2800“ F. where high
kiln is a function of gas velocity, particle size and feed
grade energy is imparted tothe materials to form cement
end turbulence conditions. The actual dust load in the
clinker.
exit gas is a power function of velocity. As shown by the
The burner assembly is mounted at the cement-elinker
product discharge end ‘of the. kiln and directs a stream of 20 data summarized in FIG. 8, oxygen usage, even with in
creased production, decreases the feed end-velocity. Low
4hot combustion products countercurrent to the stream of
raw materials. The fuel for the burner may be gas, oil or
coal. ln the case of oil, both primary air and secondary
air are utilized. In the case of gas, only secondary air -is
used. Such air is 'first passed through the heat exchanger '
or clinker-cooler where it extracts some of the heat from
the discharged product.
An oxygen lance critically positioned between the flame
and the raw material load directs a stream of oxygen into
er velocities mean lower dust loadings per unit time and
thus considerable savings in dust collection equipment.
The above invention has been described in reference to
manufacture of cement, such description necessarily con
tains limitations which in no way should beconstrued as
limitations to the inventive concept contained herein ex
cept as deñned and limited in the appended claims.
What is claimed is:
1. A method for the manufacture of cement in a ro
the lower portion of »the flame approximately at the point 30
tarykiln having an inlet end and a discharge end, which
of combustion initiation (see FlG. 1). Then the air
comprises charging cement-forming raw materials to the
supplied to :the burner is cut back to compensate for the
inlet end of said rotary kiln, injecting a combustible mix
oxygen addition and the rate of feed is increased to absorb
ture from a burner disposed above the surface of the ce
the increase in high grade energy caused by the oxygen
ment-forming'raw materials into said kiln from the dis
addition.
charge end thereof, igniting said mixture to provide a
Position of the oxygen stream as noted above is critical.
flame in said kiln, establishing a high grade energy zone
Referring lto FIG. 3a, in a standard kiln lined with refrac
at a temperature of about at least l450° F. wherein high
grade ener-gy »is supplied to said raw materials, and a low
air-fuel oil flame. The outermost portion lof the oil llame 40 grade energy zone at a temperature of below at least
1450o F. wherein low grade energy is supplied to said
has a `temperature of from about 3500° F. to 3700° F.
raw materials, supplying an oxygen stream to said kiln
lf oxygen is added directly into the center of the ñame
tory materials which in most cases can withstand temper
atures up to about 2900" F. and ñred with an ordinary
by adding it to primary air, FIG. 3b shows that thermal
gradients will be established in the llame. The outermost
from said discharge end initially directly between the
imum temperature just before being covered by the load
(point C in FiG. 2 and B’ in PEG. 4). TheV refractory
charge end'thereof, igniting said mixture to provide a
flame in said kiln, establishing a high grade energy zone
at a temperature of about> at least 1450° F. wherein high
grade Venergy is supplied to said raw materials and a low
grade energy Zone ata temperature of below at least
l450° F. wherein low grade energy is supplied to said
raw materials, supplying an oxygen stream to said kiln
burner and the raw material load in a direction substan
45 tially parallel to the axis of rotation of the kiln to cause
portions of the flame will increase to about 4000°
an increase in the high grade energy and a decrease in the
Since the outer flame is much hotter, the rate of temper
low Kgrade energy while keeping the total energy available
ature input »to the refractories will be greater. FIG. 4
to said raw materials substantially constant and con
shows what can be expected in such a situation. The
trolling said feed rate of such cement-forming raw ma
line a-a’ represents the temperature of the solids for one
revolution of -the kiln, when firing with an ordinary air 50 terials to said rotary kiln to absorb the increase of high
grade energy such that a condition of substantial thermal
fuel flame. With the same fuel rate when oxygen is added
balance is established in said rotary -kiln whereby a sub
to the primary air the line c-c’ represents the tempera
stantial in-crease in production and reduction in fuel con
ture of the feed solids. ln the latter case the radiation
sumption and dust per barrel of cement produced is real
component and absorption component energy transfer to
ized.
the solids will greatly increase. ln the case of air tiring
2. A method for the-manufacture of cement in a ro
the refractory as it emerges from the raw material load
tary kiln having an inlet end and a discharge end which
(point A in HG. 2 and point B in FIG. »4) is cooler than
comprises charging cement-forming raw materials to the
any other point in the circumference of refractory but is
inlet end of said rotary kdm-injecting a combustible mix
hot-ter than the load. On rotation, the refractory, being
exposed t0 direct radiation from the liame and convec 60 ture from a burner disposed above the surface of the ce
ment-forming raw materials into said kilnfrom the dis
tion from the moving combustion gases will reach a max
gives up heat to the feed solids and cools back to tem
pera-ture B" at point A.
'The curve d-d'----d” represents the same cycle for a
kiln being fired with an oxygen enriched flame. In this
case the refractory material reaches the maximum tem
perature B’ at a point Y. To prevent damage to »the re
fnactory materials they must again be covered by the feed
solids. In order to do this, the rotational speed must be
increased, perhaps -by as much as 2 to 3 times.
'
FIGS. 3c and 5 show the beneficial resultsobtained
when oxygen is added according to the method of the in
from said discharge »end initially directly between tie
burner `»and-the raw material load in a direction substan
tially parallel to the kaxis of rotation of the kiln, on a line
drawn from the center of such flame to the -center of mass
of Such raw materials in said rotary kiln, to cause an in
crease in the high grade energy and a decrease :in the low
vention. FÍG. 3c clearly indicates how the high emissivity 75 grade energy while keeping the tota-l energy »available
spi/aro?
n
t
substantially constant to said raw materials, and control
ling said feed rate 0f such `cement-forming raw materials
to said rotary kiln to absorb the increase of high grade
energy such that a condition of substantial thermal bal
ance is established in said rotary kiln, whereby a substan
the kiln, reducing the quantity of air delivered to said
air-fuel llame to control oxygen in said exhaust gas, and
controlling said feed rate of such cement-forming raw
materials to said rotary kiln to absorb the energy provided
by the addition of such oxygen stream to such air-fuel
tial increase in production, and reduction in fuel con
sumption and dust per barrel of cement produced is real
flame to restore a condition of substantial thermal bal
ized.
tion, and reducing fuel consumption per barrel of cement
produced and the dust per unit of cement produced.
3. A method for the manufacture of cement in a ro
tary kiln having an inlet end and a discharge end which 10
comprises charging cement-forming raw materials to the
feed inlet end of said rotary kiln, establishing an air-fuel
llame from a burner disposed above the surface of the
cement-forming raw materials at the discharge end of
said kiln, directing such flame longitudinally into said
kiln from adjacent the discharge end thereof to supply
energy needed to cause chemical and mechanical changes
in said cement-forming raw materials, discharging ex
haust gas from the feed inlet end of said kiln, supplying
an oxygen stream to said kiln from such discharge end
initially directly between said air-fuel llame and the raw
material -in a direction substantially parallel to the axis
of rotation of the kiln, and controlling said feed rate of
such cement-forming raw materials to said rotary kiln
to absorb the energy provided by the addition of such 25
ance in said kiln thereby substantially increasing produc
6. A method for the manufacture of Portland cement
in an inclined rotary kiln having an inlet end and a dis
charge end which `comprises charging cement-forming
raw materials containing calcareous and argillaceous ma
terials to the feed inlet of said inclined rotary kiln, estab
lishing an air-fuel llame from a burner disposed above the
surface of the cement-forming raw materials at the dis
charge end of said rotary kiln, directing such flame longi
tudinally into such kiln from adjacent said feed discharge
end thereof to supply energy needed to calcine said cal
careous materials and to further heat such calcined ma
terials and said argillaceous materials to a temperature in
the range of from about 2li/00° F. to about 2S00° F. to
oxygen stream to such air-fuel frame to restore a condi
form Portland cement cliuker, discharging exhaust gas
from the feed inlet end of said rotary kiln, supplying an
oxygen stream to said kiln from adjacent the discharge
end thereof, initially directly between said air-fuel flame
tion of substantial thermal balance in said kiln, thereby
and said cement-forming raw materials in »a direction
substantially increasing `production, and reducing fuel
substantially parallel to the axis of rotation of said kiln,
causing such oxygen stream to impinge the air-fuel flame
consumption per barrel of cement produced and the dust
30 at substantially the point of ignition thereof to increase
per unit of cement produced.
the flame temperature in the Vicinity of said oxygen and
4. A >method for the manufacture of Portland cement
resulting in increased energy available to such Portland
in an inclined rotary kiln having an inlet end and a dis
cement-forming raw materials, and controlling said feed
charge end which comprises charging cement-forming raw
rate of such cement-forming raw materials to said ro
materials containing calcareous and argillaceous materials
to the -feed inlet of said inclined rotary kiln, establishing 35 tary kiln to absorb the energy provided by the addition _of
an air-fuel llame from a burner disposed above the sur
face of the cement-forming raw materials at the discharge
such oxygen stream to such air-fuel flame to restore a
condition of substantial thermal balance in said kiln
thereby substantially increasing production, and reduc
end of said rotary kiln, directing such flame longitudinally
ing fuel consumption per barrel of cement produced and
into such kiln from adjacent said feed discharge end
thereof to supply energy needed to calcine said calcareous 40 the dust per unit of cement produced.
materials and to further heat such calcined materials and
7. A method for the manufacture of Portland cement
said argillaceous materials to a temperature in the range
of «from about 24Ü9° F. to about 2899" l?. to form Port
in an inclined rotary kiln having an inlet end and a dis
charge end which `comprises charging cement-forming
land cement `clinker, discharging exhaust gas from the
raw materials containing calcareous and argillaceous ma
feed inlet end o-f said rotary kiln, supplying an oxygen 45 terials to the feed inlet of said inclined rotary kiln, estab
stream to said kiln from adjacent the discharge end there
lishing an air-fuel flame from a burner disposed above
of, initially directly between said air-fuel llame and said
the surface of the cement-forming raw materials at the
cement-forming raw materials in a direction substan
discharge end of said rotary kiln, directing such llame
tially parallel to the axis of rotation of said kiln, and
longitudinally into such kiln from adjacent said feed dis
controlling said feed rate of such cement-forming raw 50 charge end thereof to supply energy needed to calcine
materials to said rotary kiln to absorb the energy pro
vided by the addition of such oxygen stream to such air
fuel flame to restore a condition of substantial thermal
said calcareous materials and to further heat such cal
cined materials and said argillaceous materials to a tem
perature in the range of from about 2490” F. to about
balance in said kiln, thereby substantially increasing pro
2800° F. to form Portland cement clinker, discharging
duction, and reducing fuel yconsumption per barrel of ce 55 exhaust gas from the feed inlet end of said rotary kiln,
ment produced and the dust per unit of cement produced.
supplying an oxygen stream to said kiln from adjacent
the discharge end thereof, Ibeneath the burner in a direc
5. A method for the manufacture of Portland cement
tion substantially parallel to the axis of rotation of the
in `an inclined rotary kiln having an inlet end and a dis
kiln and between said air-fuel flame and said cement
charge end which comprises charging cement-forming
raw materials containing calcareous and argillaceous ma 60 forming raw materials, causing such oxygen stream to im
pinge the air-fuel llame at substantially the point of igni
terials to the feed inlet of said inclined rotary kiln, estab
tion thereof thereby increasing the flame temperature in
lishing an air-fuel llame from a burner disposed above
the vicinity `of said oxygen and resulting in increased
the surface of the cement-forming raw materials at the
energy available to such Portland cement-forming raw
discharge end of said rotary kiln, directing such llame
materials, reducing the quantity of air delivered to said
longitudinally into such kiln from adjacent said feed dis
air-fuel llame to maintain at least about 1.1% oxygen in
charge end thereof to supply energy needed to calcine
said exhaust gas, `and controlling said feed rate of such
said calcareous materials and to further heat such cal
cement-forming raw materials to said rotary kilu to
cined materials and said argillaceous materials to a tem
absorb the energy provided by the addition of such oxy
perture in the range of from about 2400" F. to about
2800" F. to form Portland cement clinker, discharging 70 gen stream to such air-fuel flame to restore a condition
exhaust gas from the feed inlet end of said rotary kiln,
supplying an oxygen stream to said kiln from adjacent the
discharge end thereof, initially directly between said air
fuel flame and said cement-forming raw. materials in a
direction substantially parallel to the axis of rotation; of
of substantial thermal balance in said kiln thereby sub
stantially increasing production, and reducing fuel con
sumption per barrel of cement produced and the dust
per unit of cement produced.
8. Method for the manufacture of ‘Portland cement in
3,074,707
9
a rotary kiln having yan inlet end and ya discharge end
10
References Cited in the tile of this patent
-which comprises charging cement-forming material into
the inlet end of the kiln, establishing a llame at the dis-
«Charge end of the kiln from a burner disposed above the
surface of the cement-forming materials therein, supply- 5
ing an oxygen stream to said kiln lfrom the discharge
end initially directly between the Iburner and the cement
for-ming materials in a direction substantially parallel to
the axis of the kiln.
UNITED STATES PATENTS
797:506
19121511
2,556,542
2,820,348
Eldfed -------------- --- Aug' 15’ 1905
Wecìltef --------------- -- June 6’ 1933
Houmgsworth -------- -- June 1211951
Sauter -------------- --- Ian' 21’ 17958
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