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Патент USA US3066937

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Dec. 4, 1962
w. KRONIG ET AL
3,066,927
METHOD OF HEATING SOLIDS IN A PNEUMATIC CONVEYER CONDUIT
Filed March 25, 1960
AM
C
'F— 1
fBM
INVENTORS.‘
‘ WALTER KRéN/G, BERNl-MFPD SCHLEPPINGHOFF
ATTORNEY
“Unite States atent
3,066,927
Patented Dec. 4, 1962
2
1
or directly beneath the supply point of the solid mate
rial, since in such cases uncontrollable mixtures of cooler
conveying air and hot combustion gases are obtained,
3,066,927
METHOD OF HEATING SOLIDS IN A
PNEUMATIC C(BNVEYER CONDUTT
Waiter Kriinig, Leverkusen-Bayerwerk, and Bernhard
that is to say, the ?ow is not uniform.
Moreover, the
said possibility of reducing the quantity of conveyor gas
might contribute very substantially to the lowering of the
abrasion.
On the other hand, the method according to the inven
Schleppinghoif, Dormagen, Germany, assignors to
Farhenfahrihen Bayer Alrtiengesellschaft, Leverkusen,
Germany, a corporation of Germany
Filed Mar. 25, 1960, Ser. No. 17,480
Claims priority, appiication Germany Apr. 9, 1959
2 Claims. (Cl. 263-—-52)
ICC
tion has the advantage as compared with the use of a
10 precombustion chamber that large combustion chambers
When conducting thermal or catalytic processes in
which solids are conveyed in circulation, it is known that
the solids which have given off some of their sensible
heat to the reactants in a reaction chamber can be re
heated during the circulation in a vertical conveyor, usu~ 15
ally a vertical conveyor conduit ‘by bringing them into
of highly refractory material are not required, since the
space between the burner opening and the supply point
of the solid material is not sufficient in order also to
bring the walls to high temperatures.
By working in the said range as regards the spacing
of the burner opening from the supply point of the solid
materials, there are obtained decisive advantages over
the prior known processes, these advantages consisting on
the conveying means in the vertical conveying conduit.
the one hand in the great reduction of the abrasion and
Two methods have been developed on this principle:
on the other hand in that it is possible to dispense with
One method consists in that the hot gases are gener 20
extensive combustion chambers. The reduction of the
ated in a combustion chamber disposed in front of the
contact with hot gases which at the same time constitute
conveyor conduit and these gases are then used for con~
veying and heating the circulating solids. This process
has the important disadvantage that it is necessary, with
a relative high heat consumption to employ very large
combustion chambers and that these must moreover be
made of highly refractory materials, since very high
temperatures are set up in the combustion chambers,
these temperatures frequently being higher than 2000° C.
in order to overcome this disadvantage, another pro
cedure has been developed which consists in that the head
section of the fuel supply means is displaced into the
zone in which the conveying medium and the solids are
mixed. The ‘burner is also sometimes arranged just be
neath the supply point for the fuel into the conveying
conduit. This method has the advantage over the pre
viously described method that the hot gases being set up
at the burner are immediately cooled by the solids sur
rounding the ?ame, in that the solids immediately take 1
up the heat and thus prevent the Wall surfaces being too
strongly heated. This procedure has also proved satis'
factory in commercial installations.
It has, however, been found that when using this pro
cedure, the abrasion of the circulating solids is quite con
siderable, combined with an appreciable wear of the con
veying conduit.
it has now been found that when solids are conveyed
pneumatically in a vertically ascending conduit, with si
multaneous heating of the solids to ‘be conveyed by gases
of combustion which are generated by means of a burner
by combustion of fuels with oxygen-containing gases, the
burner being arranged below the solids to be conveyed,
it is advisable to work in such a Way that the spacing of
abrasion of the heat carrier, for example sand, which is
produced according to the invention is possibly also to be
attributed in part to the fact that the heat carrier is now
not directly subjected to the action of the ?ames and thus
is given a smaller thermal shock. However, quite apart
from this, there is also a reduction in the Wear on the
conveying conduit.
The spacing within the above-mentioned range which
is chosen in each individual case depends inter alia on
the nature of the burner. If a burner is used which has
a relatively small opening by comparison with the diam
eter of the conveying conduit, the spacing of the burner
opening from the supply point of the solid material will
be brought closer to the upper limit of the said range.
If a burner is used which burns on a relatively large
surface, for example, if the burner consists of several
openings, the Spacing between the burner opening and
the supply point of the solid material Will be brought
closer to the lower limit of the range.
The invention will be further described with reference
to the accompanying drawing forming a part of this
speci?cation and illustrating by way of example a por
tion of an apparatus for carrying out the process of the
invention.
Referring to the drawing, F represents the conveying
conduit through which the conveying gas, as for exam
ple air, is passed upwardly. The solid heat-carrier par
ticles are introduced into the conduit F through the pipe
C. A burner B provided with a burner mouth BM is
arranged in the conduit F below the inlet point for the
solid particles from the pipe C into the conveying con
duit F. The burner mouth is arranged in the conduit so
that the distance A from the burner mouth to the inlet
the burner opening from the inlet point of the solid which 55 point of the solid particles into the conveying conduit is
is to be conveyed is about 1 to 5 times and advanta
from 1 to 5 times the diameter D of the conveying
geously 1.5 to 3 times the diameter of the conveyor con
conduit.
duit at the point where the solid substances are intro
The following example further illustrates the present
duced. By the term “burner opening” is to be under
stood the upper portion of the head section of the fuel 60 invention without limiting it thereto.
supply arrangement.
When using this burner arrangement, it is possible to
lower the quantity of the conveying gases by about 20%
as compared with the quantity which must be de?nitely
Example
A stream of sand granules with the size 0.5 to 1.2 mm.
is circulating in a system which consists of a vertical
conveying conduit, a supply container and a reaction
maintained with the known process in order to prevent a 65 chamber. The sand granules are conveyed upwardly by
disturbing falling back of the solid materials to ‘be con
pneumatic means in the conveying conduit and at the
veyed. With this procedure, an appreciable reduction of
same time are heated to a temperature of approximately
the abrasion by the solid material is achieved, probably
825° C. By way of the supply container, the heated
because of the fact that a substantially uniform tempera
sand reaches the reactor in which it gives off some of its
ture and correspondingly approximately uniform ?ow is 70 sensible heat to the reactants in order then to return at
a temperature of about 700° C. into the conveying con
set up at the inlet point of the solid materials, which
duit. The supply of the sand into the conveying conduit
cannot be achieved if the combustion only occurs above
3
8,066,927
is e?ected in a concentric annular manner from slots.
About 25 tons of sand per hour are circulated with an
input of a quantity of conveying air of 1900 standard
cubic meters per hour. The spacing of the burner open
ing from the supply point of the sand was in this case
0.2 times the diameter of the conveying conduit at the
sand supply point. The hourly abrasion of sand was
in the region of 40 kg. Furthermore, with the installa
tion in operation for a long time, a clear indication of
wear was found in the conveying conduit.
On the other hand, if the burner, under otherwise
identical conditions, is disposed at such a lower level that
the spacing of the burner opening ‘from the sand supply
point is 2.5 times the diameter of the conveying conduit
4
We claim:
1. Method of transferring heat which comprises intro
ducing solid divided heat-carrier particles into an ascend
ing gas stream and pneumatically conveying the same
upwardly in said stream, heating said particles with hot
combustion gases without change in their physical struc
ture by introducing the hot combustion gases as a sepa
rate stream into said ascending gas stream at a point
below the point of introduction of the particles and
10 spaced therefrom one to ?ve times the width of the as
cending gas stream at the point of introduction of the
solid particles, transferring the heated particles to a zone
to give up a portion of their sensible heat and recycling
at the said supply point, the hourly quantity of convey 15 the same to said ascending gas stream.
2. Method according to claim 1 in which said hot com
ing air could be reduced to 1500 standard cubic meters
bustion gases are introduced into said ascending gas
without impairing the uniformity of the sand supply,
stream at a point below the point of introduction of the
particles and spaced therefrom 1.5 to 3 times the width
without the sand supply being interrupted. The sand 20 of the ascending gas stream at the point of introduction
of the solid particles.
abrasion was reduced to 20 kg./hour and the wear in
whereas it was not possible with the ?rse-mentioned ar
rangement to lower this quantity to below 1900 meters
the rising pipe decreased appreciably.
References Cited in the tile of this patent
Similar good results are also obtained if other heat
carriers are used which can be also catalytically active,
UNITED STATES PATENTS
especially such heat carriers which tend to have interior 25
tensions upon heating which cause a crumbling to pieces
2,572,484
Howle et al ___________ __ Oct. 23,
of said carriers if they are subsequently subjected to me
2,612,263
Slavick _____________ __ Sept. 30,
chanical stresses. Examples of such heat carriers are
2,621,034
Stecker _______________ __ Dec. 9,
ot-aluminum oxide or such substances as aluminum oxide
2,746,735
Bradford ____________ __ May 22,
gel or silica gel.
2,809,023
Schoenmakers et al. ____ __ Oct. 8,
1951
1952
1952
1956
19,57
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