Note: Descriptions are shown in the official language in which they were submitted.
77
; The invention relates to the intensification oE trans-
port processes by which heterogeneous chemical reactions can be
carried out in a continuous operatlon.
In everyday industrial practice, transport processes
such as impulse transport, component transport and heat transport
are of importance, and the physical and chemical operations are
realized through such processes. A great number of technical
:j ;
solutions and types o~ equipment have been developed for carrying
out transport processes. Transport processes take place when
substances are dispersed, when suspensions, emulsions or foams
are produced or sprayed, when substances are extracted or a gas
is allowed to be absorbed by a liquid or when substances are
coagulated in order to suspend the dispersed state of the sys-tem,
~etc.
I On carrying out homogeneous and particularly hetero-
! geneous chemical reactions all types of the transport processes
,l take place though the transport of components and heat plays an
-i . -
;`Z essentially important role. `
. . . .
In industrial practice, stirring is a frequent and
widespread operation that realizes actual transport processes by
means of stirrers and devices equipped with stirrers. The oper-
., ,
ation of stirring, the development of stirrers, the theory ofadmixture, and the apparatus suitable for solving various tasks
have a very extensi~e literature [see Gabor FEJES: Ipari kevero-
berendezesek. (Industrial stirring equipment). Muszaki-Konyvkiado,
Budapest, 1970. (in Hungarian)].
All of the various types of stirrers in widespread use
for the stirring of solid and li~uid materials, such as two-armed
,. . .
; ; kneaders, screw kneaders, epicyclic kneaders, colloidal mills,
' ~
special ball mills, blade stirrers, impeller stirrers~ anchor
i stirrers, stirrers in stocks, propeller stirrers, turbine stirrers,
-! disk stirrers, MIG (a trademark)-type stirrers (impulse-counter-
~: :
. j .
~g~ 7
current stirrers with several velocity steps), band stirrers,
modified turbine and disk stirrers (dissolvers, super-stirrers)
I etc. have the common geometrical main characteristic that -the
agitator extends to three or at least two dimensions, it has a
length and a breadth, and these dimensions are significant also
in relation to the dimensions of the stirring space.
It is known that in case of the blade stirrers applied
already since the earliest times the shear force created at the
j edges of the blades is responsible for the stirring effect whereas
- 10 the surface of the blade must exert a force against the resistance
of the liquid, against the intrinsic friction of the medium. The
propeller stirrers where in the course of the torsion the resis-
.. ..
tance of the liquid decreases against the b]ades, originated froma development subsequent to this recognition, namely from the
twisting of the "blades" at a certain degree, with practically
unchanged shearing edge lengths. This is expressed also in the
`~I fact that the efficiency uptake of propeller stirrers is lower
` than that of blade stirrers.
I A further increase of the length of shearing edges and
..
~¦ 20 at the same time a relative "decrease" of blade surfaces is
''"! attained in the case of the turbine stlrrers where 4 to 12 blades
l` are fixed to one disk and eventually these blades are positioned
i;.i . . .
obliquely.
Although the length of the shearing edge does not
increase relatively in the case of the disk stirrers having no
blades, the resistance of the liquid is low due to the horizontal
stirring surface, and although these stirrers can be rotated
; at extremely high peripheral speeds their stirring efficiency is
still relatively low due to the low transport efficiency of the
~; ~ 30 stirrer. In order to attain a further increase of the shearing ~
~' ~i :,. : ,
~` edge the edge of the disk is "cut-in" and these cut-in portions
, .
~ ' ~ are bent at an angle of 45 or at a smaller angle to the plane of
'~ - 2 -
,.:. '. ,
~; . ~ , .
1477
the disk, like saw-teeth. These are the so~called cogged disk
stirrers or super stirrers (dissolvers).
Another common characteristic of these stirrers is that
the agitator elements which are two or three-dimensional, are
rigidly fixed onto the pipe end of the ayitator i.e. onto the
stirrer axle.
Owing to the two- or three-dimensional nature and rigid
fixation of the stirrers, the increase of their speed of revolution
is limited, besides the resistance of the liquid, also by their ;~
mass that is denoted for design purposes, as ~crit' the critical
angular speed, and that is inversely proportional to the square
root of the mass of the stirrer. `~
According to the literature, stirring is weak when the
peripheral speed of the stirrer is below 4 m/s, it is moderate
at peripheral speeds from 4 to 7 m/s and is strong when the
peripheral speed is 7-11 m/s. Other stirrér ~types used for the
stirring of heterogeneous phases such as two-armed kneaders, e.g.
the Z-stirrers, screw kneaders, epicyclic kneaders etc. are of a
well-defined three-dimensional type and they are operated in
,: .
general at low speeds.
1~ Homogenizers such as colloidal mills, hiyh-pressure
;1~ homogenizers, and special ball mills disperse the phase in a way
J~ ; quite different from that taking place in stirrers. Still even
in these homogenizers where the liquids are forced to flow at
hlgh~speeds, the agitators~have well-deElned surfaces, e.g. in
ca~se of the colloidal mills two con1cal smooth or grooved surfaces,
one o~ which remains stable whereas the other disperses the
material~at a high speed. From the aspect of their efficiency
the~dimension of the slit is of decisive importance~ It used to
30 ~ be~between 0.01~and 3 mm. ~ ~ ;
B~all mills disperse in another way, almost 60~i of the
. ~ ~
stirring space is filled up with balls of various (0.3-3 mm) size,
! . , .
`- ~ 4~77
and these balls are moved in the medium to be dispersed by some
sort of stirrer.
At the dispersion of heterogeneous phases by means of
stirring the significance of the Reynolds number has long been
recognized. When this number is lower than 3000 the flow is
denoted as a laminar one whereas at higher values there is a
turbulent flow. It is also known that it is of advantage if
~-/ transport processes are carried out in the region of turbulence
~' flow.
Besides the characteristics of the liquid, the value of
the Reynolds number depends in the case of rotated stirrers on
, the diameter of the stirrer (_) and the number of revolutions ~n) F
denoted also as peripheral speed. In order to increase the speed ~ i~
of transport processes the peripheral speed o the stirrer must
be raised by inGreasing the diameter or the number of revolutions
~J
; or simultaneously both parameters~
~;~ In the case of rotated stirrers e.g. turbines, pro- ;
pellers andthe increase of the number of revolutions is limited
' by the value ~crit whereas according to experiments made duringconstructional work the most avourabIe ratio D:d of stirrer
diameter (d) to the diameter of the stirrer device (D) is generally
3. Chemical reactions in heterogeneous phase are fundamentally
~'! affected by the dispersion of the ciomponents, i.e. o the reactants
present in various phases. Reaction takes place only at the
interfaces o the phases. Thus~, the reactants must diffuse at
first~into these~interaces and after the termination of the '~`
reaction the formed products must leave these interfaces by
diffusion.
Since the rate o the chemical reaction is in its strict
~30;~ sense essentia1ly higher than the difusion rate, the time require- _
ment of this operation is determined b~ the difusion and the
interface. The role o the interface is o particu:lar significance
4 -
: 3~
77
in the heterogeneous reactions where the reaction is not iso-
thermal but is combined with the production of heat. In such
cases besides a significant concentration gradient also a thermal
gradient is being formed and this latter leads in the majority i-
of cases to an undesired shift of the equilibrium of the reaction
i.e. to the formation of detrimental by-products that decrease
the yield.
In order to raise the rates of material transport
, .
(component transport) and of heat transport the degree of dis-
persion of the phases is increased, the interface is increased
and the length of the path of diffusion is reduced by which -
measures it is attempted to decrease the time required for the
operation.
It is attempted to raise the rate of the transport
process and the density of the impulses, components and heat flow
by their intensification.
. According to the interpretation of up-to-date dynamic ~ ;
thermodynamics ~see Dr. Pal Szolcsanyi: Vegyipari muveleti
egysegek energetikai analizise (Energy analysis of unit operations
20~ in the chemical industry.) Muszaki~Konyvkiado, Budapest, 1972,
p. 296-324 (in Hungarian)}, intensification means most frequently
the rate increase of a process, the rate increase~of the t~ansport
of impulses, components and heat in the same volume and on the
.:
same surface, respectively.
According to the~analogy of fundamental transport pro-
cesses, an intensification of the transport of components and of
heat is possible only~at the cost~of inoreasing the impulse
tran~sport provided the transport surace is constant.
~ Further possibilities of intenslfication are: ~
;~ 30;~ increase of the surface,~more exactly of the specific
surface~per uni~t volume,
artificial inorease of the turbulence,
~7
~ decrease of the thickness of the border layer (more
. exactly the decrease of the thickness of the laminar sublayer).
-j Also in the case of chemical reactions in heterogeneous
I phase, these faetors, i.e. the intensification make possible the
`~, decrease of the gradients of concentration and of heat, until
these gradients approach zero, and the operation can be carried
Il out in a continuous way.
j . .
Continuous operation offers the advantage that equip-
ment of smaller size is sufficient, a product of more homogeneous
-I 10 composition and of a consistently good quality is obtained with
a smaller amount of by-products, in a more economical and more
~ efficient way
;~1 We found in our experiments conducted in order to
intensif.y the transport process that intensification is attained ;
in a qualitat.ively more efficient way by altering the usual
geometrical dimensions of the agitator elements i.e. by applying ~ .
¦ ~ novel agitators: point-like agitators P and line-like agitators
!~ w.
These novel agitators accordlng to the present invention :
consist of point-like elements P and line-like elements W.
... ~` ~ . .
.~ ~ I The point-like element~ P that are practically dimensionless .~
in relation to the space to be intensified may be considered to ~ ~ .
.....
have zero dimension whereas the line-like elements W that extend
... . . . ..
I practically in one direction /in length/ in relation to the
1 . .
space to be intensified may be considered as one-dimensional
elements. ~-
According to the present lnvention there is provided
an agitator for the intensitification of fluid-fluid transport
., ~1 . .
processes, comprlsing a rotor having thereon a multiplicity
: of filamentary elements, the elements having a thickness-to-
:
length ratio of 1:~50 to 1:5000^and a thickness of 10-5000 ~Im~
there being several thousand said elements on the rotor.
- 6 -
?
3~ 7
The present invention also provides a device in which
the filamentary treatment elements are fixed to the periphery of
i a rotary shaft so as to be radially extending.
~ The agitator elements according to the present invention
i are shown in Figures 1 to 6.` In the accompanying drawings, Fig.
la is a somewhat schematic view of point-like a~itators;
I Fig-; lb is a somewhat schematic view of line-like
! agitators;
Fig. 2 is a schematic view of point-like agitators
in combination with a rotor;
~; Fig. 3 is a somewhat schematlc view of point-llke
agitators attached to a rotor;
1 : .
Fig. 4 is a somewhat schematic view of line-like
agitators in combination with a rotor;
Fig. 5 is an enlarged fracJmentary view of line-like
: ,: .
agitators on their support structure; and
F~g. 6 is a somewhat schematic view of structure for
i ~ int~oducing gas into a liquid as an aspect of the present
'~ invention. Owing to the limited possibilities of figure size
the agitator elements could not be reproduced proportionally to
the dimensions, and so the figures serve only for facilitating
the understanding of the novel elements. Fig la exhibits in
, general the point-like elements P of zero dimension whereas ~ ;
Fig. lb ~he line=like one-dimensional elements W.
These~agitators consistlng of the point-like elements
P~of zero dimension and~of the line-like one-dimensional elements
W can~be operated~a~s~passive or actlve agitators and/or in a
combined way~a~ both.
The agitator is a passive one when the point-like
elements~ Pp or~the~line-like elements Wp do not introduce external
energy, they can~move, rotate or vibrate freely to the various
ph~ses, cfEering~ some reslstance to the waves created by the
known agitator I (Figures 2 and 4).
The passive point-agitator elements Pp are from the
aspect of the phases inert, solid, aniso-dimensional particles
of homogeneous or heterogeneous dimensional distribution whose
dimensions range from 1 to 2000 ~m (Fig. 2).
I Their main characteristics are, the so-called greatest
I diameter d, the number sz of particles present in the space to be
;~ intensifièd, and the total length ~ of the agitator elements `
~:~ which is in case of homogeneous elements the imaginary sequence
of a number sz of elements of the dimension q:~ = sz . q .
The elements of the passive line-agitator Wp, (Fig. 4)
are in respect to the material phases similarly inert, being
; . . .
constructed of a solid elastic material, expediently of a metal
.~ ,
;~ or plastics. They may be linear, wave-shaped, curved or twisted.
Their main characteristics are, the "diameter" of the element
Wp, its thickness q, the length Q of the elemen-t which may be
identical or diverse, and the number sz of the elements. Their
. .' . _ ....
.?~ `~ main criterion is that the thickness q of the elements ranges
from 10 to 5000 um, and the proportion of thickness to length ~--
~1 ;20 (q:Q) may vary between 1:5 and 1:1~00. One of thelr important
t `~ characterlstic~is the total length of (~Q) of the eLements (Wp)
which is in case of elements of identical length the product of
the length Q of the individual elements and the number sz of the
elements: ~Q = sz . Q.
The~number sz of the psssive agitator elements may be
so~great that they fill up at least 0.01% of the total volume of
the~phases, although it must not~exceed the level at which the
phases~can be maintained still in~a fluid state with the known
i ~ or novel agitators I.
,~ 30~ ~ ~ Agitators~are denoted as active when by means of them
` ~ energy~originatlng~from an external source is lntroduced into
bo ~ a to `-~ }~ en~if1ed ~F g re~ 3, ~ a d C). Suoh external
-
` ; IL~41~7
energy may be mechanical energy
The active agitator elements Pa, Wa may be fixed to an
agitator shaft end or ends or to some surface J which may be
stationary or moving over the phases or in the phases in a
linear, rotating or varying direction and curvature, with a ;~
continuous or vibrating motion which motion is maintained by an
' external energy source
-` The main characteristic of agitators consisting of the
; active point-like elements Pa and of the line-Iike elements Wa
is similarly the diameter q, the length Q of the element, the -
number sz of the elements and the total length of the agitator - -
.i .,. , ~.
elements ~Q
At the active line-agitators Wa (Fig 5) where the
-~ ratio of the elements q Q may vary from 1 10 to 1 5000, the
.. . .
elements Wa are fixed at one point or several points to a surface
J although they can freely deviate, move and vibrate The
elements Wa that are inert in respect to the material phases are
constructed of solid elastic materials expediently ~of a metal
or plastics though they may consist also of a gas or liquid
(Fig 6)
Common characteristics of these novel agitators are
further, the agitator surface (F) the sum of the surface of the
' agitator elements (P,W) and the agitator volume (Q) the sum of
;,~ the volumes o the elements (P,W)
In comparison to the known agitator volumes the
agltator~volume Q is the 1/4~to 1/10 part of the former while
b~gitator su~face is at least of the same order of magnitvde
!~ 9 _ , ;
477
; as the surface of known agitators but in most cases it exceeds
their surface. Consequently, the surface per unit volume of
`j the agitator, the specific surface F/Q is essent.ally greater
(by an order oE magnitude) than that of the kno~n agitators :~.
whereas the agitator volume Q/F per unit volume of the agitator
is essentially lower than that of the known agitators. This :~
. means at the same time that the mass of the agitator and the
agitator mass per unit surface is of a lower order of magnitude. ~:
The differences become even more conspicuous on comparing the
total length ~Q of the agitator elements (the length of the ~ ~
i shearing edgesj in case of the known agitators with those of the .~:
novel-type agitators P, W. The total length referred to unit :
! volume and unit surface, respectively, of the agitator is about :
.. 1. the tenfold to hundred-fold value of that of conventional .. :
agitators. On examining the same total lenyth per unit oE the 1
! :
j space to be intensified (total length density), the obtained ::
value ~Q/V will be the tenfold to thousandfold value of the
data given for the known types of agitators.
~ In the course of a great number of experlments with
1 20 the novel point-agitators P and line agitators W according to
the present invention we have found that the high specific surface
j and length density of the agitators are responsible for their
` capability of intensification.
.l We have found that the rate increase of the transport
~: ~ processes, the intensification of the dispersion is the more - ::
efficient,
the lower is the radlus of curvature of the
i elements _, W,~and the more the value of q/2 approaches the
submicroscopic~dimension,
30 ~ - the:gr:eater is the specific agitator surface _/Q, .:
the higher is the length density ~Q/V of the
agltator, and
,, ;:.:, :,~ " :
~1~4 ~1L?~ 7 7
- the longer is the path Z covered by the agitator
elements P, W in the phases during unit time.
The path Z covered in unit time in the space to be
intensified depends e.g. in case of a rotating active line-
agitator Wa on the diameter of the agitator/indirectly on the
length Q of the line element (W), the number sz of the line
- elements and the number of revolutions n of the agitator: in
that Z = d . . sz . n .
- According to what has been said above the intensifying -effect of the agitators of novel type according to the invention, -
consisting of point-like elements P and line-like elements W can
be attributed to the essential increase of the density of the
. impulse flow which latter is known to be the prerequisite of
increasing the density of components flow and heat flow. This
means that the effective density of mass flow is increased sudden-
ly by these agitators.
On applying zero-dimensional point-agitators and one-
dimensional line-agitators
- the specific surface of the phases increases, ~;
.. ..
- the turbulence increases, and
- the thickness of the border layer, of the so:called
laminar sublayer decreases.
, .:
~; In the case of passive agitators the increase of tur-
bulence is due to 'tsecondary" turbulences created by Pp, Wp ~j; i!
agitator elements that are moving, rotating and vibrating freely
i~ ~ in the phases when the isobar flow surface created e.g. by a known
agitator, a propeller stirrer is augmented by the point-like -~
elements Pp and line-like elements Wp, and at the same time the
border layer between the turbulent centres created by the stirrer
~-~ 30 Ithe laminary sublayer) is mechanically made thinner by a _ ~
'secondary" turbulence created in this sublayer. --
In the case of active agitators the turbulence -
,'~
increases owing to the high Re number created by the higher
number of revolutions attained as a consequence of their relative
mass decrease. At the same time, owing to the high length
density of the agitator and the increase of the number of
~ turbulent centres the laminar sublayer located between them
i` becomes thinner and thinner due to the vibration of the agitator
elements.
~,j
The great specific surface of the novel agitators
according to the invention is achieved with a mass of relatively
lower order of magnitude than that pertaining to the known
agitators. In this way it is possible to attain a high number of
revolutions in a liquid a peripheral speed exceedlng 30 m/s/
l without any self-osclllation of the agitator axle since the
~ agitator is capable of balancing itself in that the agitator
;~ elements W, P arrange themselvès according to the frictional
conditions of the liquid. :
.,
We have examined the technical parameters of the pre-
paration of an oil/water emulsion by meàns of an embodiment of
the novel agitator according to the present invention, namely
~- 20 a rotating agitator containing line-elements Wa, and for the
: , ,
~- sake of comparison, also by means of a known agitator, the
~ ~ turbine stirrer. In the nine series of experiments conducted
.;'. , , ~ . :
by us (three of which were experiments carried out with turbine
stirrer and six were with line agitator), the parameters of the
experiments were kept constant throughout in that a mixture of
.~ .. , ~ , . . . .
:~ ~ : 100 ml of oil and 1000 ml of water (V = 1100 ml) was emulsified
in a~beaker of a diameter D - 130 mm. The diameters of both
types~ of stirrer ~d = 43 mm) were equal to seven series of
experiments~whereas in ~wo series ~No. 8 ànd 9) the diameter of
30 ~ ~ the 1ine~agitator was~d = 80 mm. The agitators were placed at
a~helght of h =~;30~mm from the bottom~ of the beaker. The same
- electr~omotor wa~s;used in all the experiments, its number of
i~
4~Y~
. .
revolutions in neutral gear was n = 4200 li l/min. The height
of the turbine blades was chosen so as to be equal to that
i (M = 8 mm) of the line elements Wa at the surface generated by
rotation of the stirrer axle.
The efficient stirring period of emulsification ( s)
was measurea by a method descr1bed in the literature [J. Burger,
Magyar Kemikusok Lapja 10, 466 (1962)] in that light was trans-
mitted through the stirring vessel, and the change~ of ligh~
intensity with time were measured. When no changes in light
intensity were perceivable (the trànsmi-tted llght remained
stable), the period was considered as the time required for
', .,
efficient stirring. Then the obtained oil/water emulsion was
poured into a graduated cylinder and the time _ (min) required
for the complete sepàration of the emulsion was measured.
I During stirring, also the number of revolutions of the
~ loaded stirrer Nk ~ t was measured by means of a revolution
¦~ counter.
The results of these comparative experiments are shown
in Table 1 (the individual data of mèasurements are mean values j~ !
of ten measurements each). The symbols used in this table are
as follows: ;
diameter (mm~ of the agltator
sz : number of agitator elements (blade number, number
of line elements),
F : surface (mm ) of the agitator,
Q : volume (mm3) of the agitator, ~ ;
nk : number of revolutions (per min) of the loaded
stlrrer,
F : specific surface (mm /mm ) of the agitator,
~ ~ . total length (mm) of the agitators,
Q/V : total length density of the agitator referred
to unit of the stirred volume (mm/mL),
;~ 13 -
. :j ' ~ ~' '''`.,,
3L'3~3~477
r time (s) required for efficient stirring.
The length L of the blades, and, respectively, of the
~ line elements Wa were 14 mm in series 1-7 of the experiments
.;~, and 32.5 mm in series 8 and 9. The ~Ithickness~ of the line
~ elements Wa was q = 0.5 mm, and the ratio of diameter to length
;~ q:Q was 1:28 in series of experiments 4 to 7 whereas it was
.
.~ 1:65 in series 8 and 9.
In respect to the series of experiments 1-3 it appears
from Table 1 that the decrease of the numbers of revolutions is
22-26%. With the increase of the number of blades the stirring
~ periods slightly decrease to very short periods, and the time
;~ required for thè complete separation of the emulsion practically :
`.~ does not alter (12-14 minutes). ~: .
:~ In the series of experiments 4 to 7 when line elements .:`
:
Wa of an identical lenyth Q were applied which were flxed at one
'j point to the revolution surface J on the axle while their other
. ~ ends moved freely, the number of revolution decreased only by ;
` ! ~', : `.
I ~ 13-14~ at an unchanged value of D~d while the time r required ~: :
for admixture was reduced by 50% and at the same time the period
required for separation ( ) increased to an 8-10-fold value.
: ~ Thus, under the same experimental conditions the
. ~ efficiency-requirement of the novel line agitator Wa lS lower - ;
~ by about 30-40~, the time required for the efficient stirring
J~ is reduced to half of the conventional value, and the emulsion
~ : remains stable f~or~periods longer by 8-10 times. This may be
t`;~ expr~essed~also in that the novel agitator Wa disperses more
efficlently with a:lower amount of energy introduced, more power
:is applied during a shorter period against the surface tension,
the ut~ilization of energy is improved to a great extent, the
~ 3Q~ amount of power utilizable technically increases in relation to
t`'^`` ~ the energy introduced in the system. In the series of experiments
: 8~and 9 when the~length Q was kept stable and where the ratlo oE
7'~
D/d was 1:62 (a value not applied in the case of stirrers of
such numbers of revolutions) the period of admixture r could be
i reduced further, and the period t required for the separation
i appreciably increased. On examinating in Table 1 the paràmeters
characteristics for the agitator elements and the tested agitator,
respectively, it is striking that at an a:Lmost identical agi-tator
surface F (series of experiments 1 and 6)/ the volume of the line
, agitator (Q) was greater only ~y slightly more than one third
than the volume of the conventional turbine stirrer. This is
proved by the fact that whereas in case of the turbine stirrer ~-
and specific agitator surface (F/Q) is 1.428 this parameter is
greater byr more than 2.5 in case of the line agitator: 3.95.
The difference is even more striking on comparing the length values
~Q) of these two types of agitator elements. In case of the
same agitator surface ~series of experiments 1 and 6) the value
of ~Q rises to the 12-fold level in case of the same agitator
volumes (series of experiments 1 and 8). The increased ~ ;
efficiency of the novel agitators can be explained by the ratio
Q/V, the length density per unit volume of the emulsion: this -;
is higher by ten to fifty than that o-f the known agitator types.
Subsequent to the above described series of experiments
:~ .
; ~ a great number of series of experiments in various directions
have been conducted in order to clear up the possibilities of
application of the novel type agitators in the field of inten-
sification of various transport processes.
, sl"~ We investigated e.g. the intensifying effect of the
.. ~.~: . ...
~ novel agitator on the solvent extraction of liquids non- -
.~ ;.~,,~ -J, immiscible with each other (see Example 3).
We found that e.g. on extracting acetic acid dissolved ~ -
~ in a higher alcohol with water at the same stirring period and
numb~r of revolutions, the amount of residual acetic acid
retained in the organic phase with the use of the line agitator
'-J~
' ~ - 15 - -
~ .
.,' . ~
: "1, :
- ~ 77
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: . ~ ~1~ ~D O 1~ 11~ ....
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011 rl C~ l ~ ` .~.
:
' 1~ ~ 8 o g g 8 g 8 ~ o
j,"~ ~ ~ ~1 ' ~ ~ ,~
~ ~ ~ ~ ~ ~ ~ ~ C~l
~ : :
'`,1 : ' Il~ ~1 ~ ~ ~ ~ ~ ~ ~ ~ ~ : ' .
;- ,~ : ~ ' ~ O O O O O O O ~D ~D
,, ~
' $ ~ 0 ~ , ;
. :
: . ~ .
h ~ ~ o~ j : ~ -~
~ ",~: ~ ~ Z : = =
ri ~ :, ~ `
:: ~ b.~ ~
h ~ h ~:: ~ D ~ oo ~ ~:
H c~ o P. ~l ~ ~ ~
~: ~ 7~
W-a will be only 1/50 of the quantity retained in the case of a
propeller stirrer.
, We investigated in our experiments the intensifying
I effect exerted on the dispersion of solid substances in liquids
l (see Example 2). Sodium bentonite was suspended in water using ~.
; a propeller stirrer and then using the novel agitator (Wa~ for
:~ the same stirring period, diameter and number of revolutions.
Whereas sedimentatilon started about two hours after the termin-
f ation of the suspension treatment with the propeller stirrer, inthe suspension prepared with the novel agitator Wa this process
.,.1 . .
began only after a fortnight. . ~ .
. On applying the novel type agitators as stirrers not ~.-
~ only the peripheral speed can be raised appreciably in relation
:' to the known stirrers but even with a free choice of the ratio :
Djd in the range from 1.2 to 3.5 also the distance h of stirrer
.l from the bottom of the device can be varied within relatively :: .
wide limits. .
rl ~
. ~n using the stirrers applied in the series of exper.i- :
ments 2 and 8 mentioned in Table 1, 500 ml of oil was emulsified ..
with 500 ml of water at a height h = 65 mm, nearly 75% of the
full height H! Whereas the turbine stirrer was practically
~: : inefficient under these conditions, on using the novel agitator
'j: ;
W we succeeded in producing by stirring for 90 seconds an
.. j -a :
?~ emulsion whose complete separation required 170 minutes. ~:: In case of the known types of stirrers, in addition to
the above mentioned~conditions, the agitator must protrude into
the stirring space,~into the interface~of the two phases, in .~.
order to attain an efficient stirring. Much to our surprise we
have found in case o~f the active agitators Wa according to the .:
~- j 30~ present invention that the rotating line agitator 1 capable of
r~ ; conduc~ing~the dispersion process even when located over the .~
~ st-rring space (at a total height~H of the phases). This meàns ~
77
that this agitator is capable of transmitting the energy origin-
ating from external energy sources to the media to be dispersed,
by the mediation of the "gas cushion" existlng over the phases.
Consequently, it is possible to eliminate contact with any liquid
phases that are corrosi~e to the agitator because also an inert
gas can be a medium suitable for energy transfer.
A great number of experiments were carried out by us
for testing the use of the novel zero-dimensional point-like
agitators P or of the one-dimensional line-like agitators W
according to the present invention, for the dispersion of solid
substances in liquids, of liquids in liquids, of gases in liquids,
of solid substances in gases, of liquids in gases, of solid
substances and liquids in gases. It is impossible to describe
all these experiments in this specification. However, we
' !` '
attempted to choose our examples in a way as to exhibit the wide
' possibilities o the application of our invention.
'`,J.' ' In the course of our further researches into the
`i application of the novel agitators according to our invention,
the continuous opera~ion of heterogeneous chemical reactions
, ~" .: .
-~ 20 was examined.
The saponificatlon of vegetable oils with alkali
hydroxides is known to be an endothermic process of long duration. -
Soapmaking is carried out in industrial practice for 5-6 hours at
,~ a temperature of 80-100C. In our experiments the vegetable oil i:
and sodium hydroxide were emulsified in the conventionàl pro-
portion at room temperature by the line agitator Wa. The fatty
acid content of the reaction mixture decreased in two hours to
` 0.5%~by weight, i.e. the saponification process was terminated
~see Example 10).
30 - On repeating this experiment in a way such that the _ -
vegetable oil and the solution of sodium hydroxide were prehsated
~`, to 60C prior to their admixture, the fatty acid content of the
i - 18 -
'' '"' ,
:~4~477
reaction mixture decreased to below 0.5~ by weight within half
an hour.
It is known (Hungarian Patent specification No. 146818,
and Schwab, G.M.: Katalyse an flussigen Metallen. Dechema
Monographien 38, 205 (1960) that hetèrogeneous organic chemical
reactions in the gas phase can be carried out expediently by
allowing the vapours of the reactants to bubble through a metal
, melt ~e.g. the decarboxylation or oxidative decarboxylation of -
~ furfural, thermal decomposition of pentane with steam, production
i~ 10 of paraffin hydrocarbons, cracking of hydrocarbons etc.). Since
the specific heat of the metal melt is higher by three orders of
magnitude than that of gases and vapours, the process can be
il carried out under isothermal conditions, and the bubbles of the
~'j vapours of the reaction mixture behave like elementary reactors.
At the same time the embodiment of the process is made more ~ ;
~ difficult by the fact that the specific gravity of the vapours is
.; .. ... ..
lower by two orders of magnitude than that of the melt and thus
; ; ~ they ascend a`nd de~scend quickly, promoting the combination of ~ ;
the individual bubbles.
On using the novel agitators Wa according to the present
invention, the vapours of the reactants are dispersed in the melt
of the metal or of a salt of the metal to such an extent that
j the sizes of the formed bubbles will be smaller by an order of
: .
magnitude, preventing thus the combination of bubbles. Moreover,
owing to the hi~gh turbulence the melt will be mixed up more
ntensively. An~ intensive turbulence of the melt is of particular -~
advantage in the case of a molten~bath of metals and metal oxides
when the metal oxide is inclined to form a film on the surface
(e.g. lead oxide)~that prevents the escape of the already convert-
; 30~ ~ed vapours. On~applying thè line agitator Wa the length of the
3 ~ opeirational period ln the melt is reduced, the efficiency of the
equipment is appreciably increased. Oxidation reactions in the
3~ 47~
; vapour phase can be advantageously realized by means of two
reactors each of which contains an active line agitator Wa keeping
the melt also between the reactors in a constant circulation. In
one of the reactors a part of the metal present in the melt is
oxidized to a defined degree by dispersing air in the melt. When
this portion of the metal enters the secon~ reactor it delivers
oxygen for the oxidation of the reactant present in the vapour
phase. Subsequently it returns to the first reactor where the
` melt is again partially oxidized etc. (e.g. the system lead-lead
oxide).
.- ' .
The novel passive and active, zero-dimensional and one-
, dimensional, point-like and line-like agitators and their applic-
; ation will be elucidated in detail by the following non-limiting
Examples.
Example 1
A rotary line agitator is rotated at 2500 rpm in a
cylindrical metal vessel of 2 litres volume. The diameter of the
~i~ agitator is 330 mm, the length 1 of the line elements Wa is 125
mm, their number sz = 3500, their thickness q = 0.8 mm. The
surface of revolution J to which one of the points of the line
' ~ elements of steel is attached is equal to 8740 cm2. The device
;/ is equipped with two pipe ends for Eeeding and one for removing
the material. The materials are ed by the feeding pipe ends ~`
onto the agitator elements in a direction parallel to the axle
o~ the rotary agitator. The removed material is introduced into
a vessel of a ~olume of 10 Q that contains 5 litres of water of
a~ temperature of 5C. Through one of the pipe ends for feeding -
~- ~ 20Q g of melted paraffin of a temperature of 90C is fed whereas
through the other pipe end 800 g of water of the same temperature
is fed. ~ ~
The~ormed paraffin/water emulsion flows from the vessel
into the;davice containing cold water where the paraffin solidifies.
20 ~
~. ~' '.
1'-'; " ' "'~ '
~.~34~7
On examining the paraffin suspension under the microscope it was
found that the obt.ained suspension consists of particles of a grain
.
. size of 0.5-1.0 ~m.
; Example 2
180 g of sodium bentonite and 3450 ml of water of a
. temperature of 60C are transferred into a cylindrical device of : ;
a volume of 5 litres in which alternately a rotary line agitator
according to Example 1 and a propeller stirrer is placed each of
which is operated at the same rpm of 5000. In both experiments
. 10 the preparation of the suspension is conducted for the same
.~ period: ten minutes stirring with each of the propeller stirrer ..
l and the line agitator. ~
~, The two types of suspension prepared in this way were ..
poured separately into glass cylinders and the rates of sedi-
j mentation observed. It was found that sedimentation started
after two hours in the suspenslon prepared by the propeller stirrer
~ and separation was completed in two days. In contrast to that, ~.
3~ ln the suspension prepared by means of the line agitator the :
~: sedimentation started only after two weeks. ;:
20 ~ Example 3 :.
The extraction with water of acetic acid from an organic
;-~ solvent immiscible with water was examlned. :
I A laboratory stirrer motor of 5000 rpm was applied, in
. .
the first experiment with a propeller stirrer o a diameter o
37 mm while in the second experiment with a rotary line agitator
,,., ~:~: ..
of the same diameter. The line elements Wa had à length of 14
mm, a thlckness of 0.2 mm and thelr number was 10000.
50 ml of a solution of n-octylalcohol containing 5.2 g/
100 g of acetic acid and 50 ml of~distilled water were transferred
; 30~ into a 250 ml beaker. The mixture was alternately stirred for
one minute each with both types of stirrer, then the o:rganic phase
wa~ separat~d from ~ater and lts res-dusl acet1c acid content
... ~ .
.~
was determined.
Results of ten consecutive measurements each averaged:
i acetic acid content of n-octylalcohol prior to
, extraction 5.2 g/100 g
acetic acid content af ter extraction carried
out with propeller stirrer 0.548g/100 g
acetic acid content aEter extraction carried
out with line agitator Wa 0.110g/100 g
It can be seen from the data of the above experiments
1 10 that the line agitator Wa carried out the emulsification during
; the same operational perlod at an efficiency higher by 50.
Example 4 -~
Experiments were carried out in order to elucidate how
gas absorption can be intensified by means of the line agitator.
On burning 2.25 g of elementary sulfur in excess air,
~i the absorption of the formed 4.5 g of sulfur dioxide gas by water
¦ at room temperature was investigated. In one series of experi-
¦~ ments the formed gas was allowed to bubble for five minutes
, ., . -:
Il through 800 ml of water whereas in another series of experiments
-¦ 20 a rotary line agitator of 190 mm diameter was rotated at~3000 rpm
in. a glass cylinder of`200 mm diameter. The total length of the
~ ~ 0.3 mm thick agitator elements Wa was 50 mm and their number was
'I 10000. ' ' "''
'l ..... ..
1 ~ The top 800 ml of water Was transferred over a period
of S minutes onto~the agitator elements, and within the same time
and~above~stated amount of sulfur dioxide gas was introduced in
oounter-current~into the glass cyllnder.
~;i ~ In both~series of experiments the contents of sulfurous ~ ~
acid was determlned: wlth~the bubbllng~method it was 1.39 g/800 ~ -
30~ ml~but~f~r the absorption with the line agltator 2.88 g/800 ml.
Thus~, with~the bubbling~method 24.3~ of sulfur dioxide
: ~ ; whereas~ wlth tbe ~ ~orption by means o- th^ line a~itator 50 1~
477
: of it were absorbed.
Example 5 . :
On the basis of the results of our experiments carried
out concerning gas absorption we examined the extent to which the
air uptake of water can be raised. This is an important factor
in the biological purification of sewage. ~.
, In these experiments a Wa line agitator of 360 mm ....
diameter with a horizontal axle, having 1650 line elements of -
- 0.4 mm thickness and 145 mm length was used. ~ ;
In a quiescent stage the agitator elements protruded . ~ .'
:' below the surface of the water. . :.
.. ..
.. The temperature of the air was 20C, its relative ~. .
. .~ ,.. .
~j humidity.S9~ whereas the temperature of water was adjusted to .:
~:~ 35C by thermostat. ~.
3f When the agitator was kept in rotation it dispersed the ; . :.
j water in the air as a 5pray. At a height of 130 mm above the .:
water surface samples were withdrawn from the water spr`ay at
various distances (O.S, 0.8, l.S and 2.0m) from the axle of the .:. :
:agitator, and the temperature and oxygen content of these samples
. f ~ 20 were established. : .
Temperature of water at start: 35CI its 2 content ~.
~J ~
4.2 ml/l on treatment with the agitator:
at a distance of 0.5 m 30C, its 2 content 5.03 ml/l
i " " " ll 0.8 m 27C, " " " 5.53 "
!~ " " " " 1.5 m 24C, " " " 5.63 "
" " 2.0 m 21C, " " " 6.06
Example 6
f;~ ~ In a cyclone-shaped device a Wa line agitator of 330
: mm d am~ter containing 4lsa line elements Wa of 125 mm elem~nt
30 ~ lenqth~and o.a ~mm element thickness was rotated at 2500 rpm~ .
. ~ . 3~ Below the rotating agitator 5 m /min of air saturated ~ .
. - 3 ~
ith~powde~ed cemenC was introduced. This a_r left the device
~; ., : : : . ~; . -,.
77
at the upper part of the cyclone.
Parallel to the axle of the agitator one Q/min of
I water was introduced concentrically.
-~ On illuminating the air leaving the device no Tyndall
, effect was observable, indicating that the air contained no
-` dust particles.
I Example 7
! In a six meter high device with a closed top and with -
a conical bottom a rotary line agitator with a horizontal axle
l 10 was placed and rotated at 2500 rpm. `
i The agitator contained Wa line elements of steel of
330 mm diameter, 0.8 mm thickness and 125 ~n length whose element
density was 4 elements per cm2 at the surface of revolution. ~ ~ -
In a stirrer equipped with a Z-shaped stirrer clay was
mixed up with powdered graphite. A graphite clay pulp with 21~ ; -
¦ moisture content was obtained.
; The pulp was introduced into the a~ove described device
.
in a horizontal direction by means of screw feeder in such a way
that the pulp was pressed through a slit of 1 by 4 cm at a rate of
4 cm/s and then sprayed along the mantle of the rotating line
agitator. Then aix heated to 100C was led into the device.
~`A,~ ` The sprayed pulp was dried over a five ~eter long path
of sedimentation.
The graphitic clay powder removed from the device ~`
contained 0.3~ of moisture, its particles were of a size of
~70 ~m.
Example 8
In a~devlce shaped like that speclfied ~n Example 7 and
whose conical part formed one third of the total heignt, a
30~ acketed agitator with a central vertical axle is placed, then
the agitator is kept in rotation at~2500 rpm, while cooling with
~;~ w~ t~ c-e~ed mantle.
~4 ~477
The cylindrical perforated ayitator of 100 cm3 volume
which is open at the top and has a mantle height of 4 cm, is ~
equipped with bores of a diameter of 5 mm. In each second bore ,
a Wa line element of 1 mm thickness and 160 mm length is fixed.
In each cm2 of the surface of revolution of the agitator 4 line ~ :~
elements are located. Below -the agitator, gas/nitrogen or oxy~en
is led into the upper third part of the device.
~, Into the hollow body of revolution of the line agitator
metallic cadmium of a temperature of 340~C is introduced as a
melt and sprayed at a temperature of 450C in a nitrogen current
in one series and in an oxygen current in another series of
experiments. When nitrogen current was applied, powdered metallic
cadmium of a grain size below 1 ~m was obtained in the conical
part of the device equipped with water cooling. `~
On spraying in an oxygen current, in turn, upon varying `~
~ the point of feeding the gas, powders containing cadmium and
'1 cadmium oxide in various proportions were obtained, depending
'l~ on the length of the path of sedimentation. In the case`of a
sedimentation length of 1 m the obtalned powdered cadmium con-
tained 11.5% of cadmium ox1de. Powders with any desired propor-
tion of metal to metal oxide produced in this way can be used for
the preparation of electrodes for storage batteries.
Example 9
' ,1 It is known that the purity of the end p;roduc-t is '
appreciably affected by the degree of dispersity of the suspension
formed upon the precipitation of reaction products ln solid state
Y~ during chemicaI reactions. Substances precipitated in solid
r',m ~ state during the precipitatlon process may contain inclusions, ;~
;; and may be purified only by repeated washin~ or recrystallization.
E.g.~N-isopropyl-2-chloroacetanilide which is a llquid and pre~
cipltates i.~e. solidifies only when led lnto cold water is
produced according to the Hungarian Paten~ specification No.
. : ~
~ 25 -
159044 by allowing N-isopropyl aniline to react with monochloro-
acetic acid in the presence of phosphorus trichloride at a
temperature of 80-100C. The substance introduced into cold
water (of 5-10C~ in a device equipped with the conventional
turbine stirrer solidifies, and is subsequently washed four
times with fresh water to obtain a product of a melting point
of 68-72C.
In a cylindrical device of 200 Q volume and 560 mm
dlameter a rotary line agitator is placed. The surface of the
hollow agitator cylinder of 100 mm diameter and 50 mm heigh-t
was equipped with bores of 3 mm diameter: in 16 segments 4 bores
each i.e. a total of 84 bores. Between these bores a total
number of 2880 Wa line elements of 100 mm length, of a steel wire
of 0.4 mm thickness were fixed at one point of their length.
The agitator was rotated at 3000 rpm at the surface of 150 litres
of w~ter of 5C.
The liquid reaction products of a temperature of 90C
were introduced in a continuous stream into the hollow upper ;
portion of the agitator. The precipitated N-isopropyl-2-chloro-
acetanilide was filtered and dried. Thé obtained flne crystalline
product had (without any additional washing) a.m.p. of 76-78C.
Example 10 -
In a cylindrical and at the bottom cone-shaped device
; of 250 mm height and 220 mm diameter a rotary agitator is rotated
at 3500 rpm on a vertical axle. The agitator consisted of W
line elements of 0.5 mm thickness and 90 mm length. Onto these
ag1tator elements 1000 g/min of edible oil and 532 ml/min of~ `
:: : -: :
~; 7.0 N sodium hydroxide solution was led and the obtained fine
emulsion (of an average grain size of 0.5-1.0 ~m) removed at the
, ,
bottom of the device.
In the first series of experiments both the oil and
the alkali fed were at room temperature (25C) whereas in the ~ `
- 26 - ~`
; ~ '' `
1~ 77
second series of experiments both materials were introduced
preheated to 60C and fed hot into the device. From the
emulsions obtained in this way samples were withdrawn at 15
minute intervals, and their contents of free oleic acid i.e. the
unsaponified part determined by analytical procedure.
In the case of the emulsion prepared at room temper- ;
ature the content of free oleic acid diminished to below 0.5 g
in two hours while in the case of the emulsion prepared at 60C
this was attained in half an hour and the saponification was
ended.
Example 11
To 500 ml of dodecylbenzene in a 2000 ml beaker 250 ml
of fuming sulfuric acid (oleum with 8% content of ree sulfur
trioxide) was added in 15 minutes. The reactiort mixture was
stirred with a laboratory-type four-blade stirrer at 5000 rpm.
Then the obtained dodecylbenzene sulfonic acid was converted
into the sodium salt with the use of sodium hydroxide, and the
:
product subjected to analysis.
~; The conversion was 43.3% ~
~ 20 ~ yield: 41.2% .~-
¦~ dry matter content: 48.2%
active detergent content: 24.3% `-
l On repeating the experiment, Pp point agitator elements
i~ of silica of individually 0.5 mm3 volumè and with a total volume
of 300 ml were placed in the dodecylbenzene, and the oleum was
introduced in only one minute with the use of the same stirrer.
~ On separating~the~ ~polnt elements by filtering, the obtained
dodecylbenzene~sulfonic acid was similarly converted into the
sodium salt,~ and the product subjected to analysis.
30~ The;oonversion was ~ 65.3~
yield: ~ : 54.2%
dry matter content: 65.3%
active ~detergent content: 45.6~ ;~
,, , , . :
~ 7 -
Example 12 ~04~477 `: -
In a device of 220 mm upper diameter and 800 mm hei~ht
with a cone-shaped bottom part a cylinder of 200 mm diameter
and 11 mm wall thickness was rotated. On the 250 mm high mantle
of this cylinder 2 bores of 0.1 mm diameter each were provided
in on each cm2. The cylinder was rotated at 2500 rpm around
a hollow axle.
Into the device 1230 ml/min of dodecylbenzene sulfonic
acid whereas into the rotated cylinder gaseous ammonia of an
overpressure of 20 atm were introduced at a feedin~ rate of
7140 ml/min. The gas left the device through the bore in the
,
cylinder wall as a gaseous Wa line agitator. From the bottom of
the equipment 1600 ml/min of ammonium dodecylbenzenesulfonate
was removed.
The thermal decomposition of benzyl homolo~ues in an -
~ aqueous medium by bubbling through a bed of melted lead is known
,. . .. ~
from the Hungarian Patent Specification No. 146818.
A reactor of 95 mm diameter equipped with electric
: ~ heatlng contains 41.7 kg of melted lead, of a volume of 3674 cm3
and a surface of 61.2 cm2. A mixture o~ gasolene vapours and
steam is~led below~the surface of the lead melt: evaporating
60 ml/h of gasolene and 60 ml/h of water. The temperature of
the melt was 700C.
.. .
~ The amount of the ~ormed gas was 50 litres/h, its
.:
; calorific value 9?76 kcaljm3 and its composition: 0.1% nitrogen,
2.5%~hydrogen,~48;.0% methane, 0.4% oxygen, 15.6% carbon monoxlde,
1.6% oarbon~dioxide and 21.8% unsaturated~lower hydrocarbons.
The~same process was then carried out in equipment
consisting of~two aylindrical vessels, an~upper~part of 95 mm ;
30~ diame;ter~and a lower part of 250 mm diameter attached to the
upp~er~one.~ In the~lower part of greater dlameter of the equip-
ment there~was~a~rotating agitator o~2Q0 mm dlameter, 2 mm
~ 28 -
~4~477
thickness and 80 mm length containing 700 Wa line elements under
which agitator the mixture of steam and gasolene vapours was
introduced. The agitator was rotated at 2500 rpm.
I On feeding a mixture obtained by the evaporation of
I 850 ml/h of gasolene and 850 ml/h of water, we obtained from
¦ the equipment through the lead melt of a -temperature of 700C
an amount of 700 litres/h of a gas mixture of a calorific value
! of 11785 kcal/m3.
The composition of this gas mixture was: 1.0% nitrogen,
l 10 0.7% hydrogen, 46.3~ methane, 0.6% oxygen, 6.8~ carbon monoxide,
¦ 2.2% carbon dioxide and 34.4% of unsaturated lower hydrocarbons.
Example 13
Similarly to the process specified in Example 12,
`' conversion into furane was carried out on feedin~ furfural, air
and steam into a device where the mixture was allowed to bubble
through a bed of melted lead and with the use of a rotary line
¦ agitator, respectively. The bed of melted lead was in both
cases of a tempèr`ature of 320C.
Feeding rates during the bubbling procedure were: i
~20 70 ml/h of furfural, 75 mljh of air and 20 ml/h oE water. The
furane yield was 50 ml/h.
In the experiment with the Wa line agitator the feed-
I ing rates were: 700 ml/h of furfural, 750 ml/h of air and 200
;~ ml/h of water. The furane yield was 500 mljh.
The amount of the applied melted lead was the same in; al1~the experiments described in Examples 12 and 13.
": .~
~ 29 -
;1 ~
: ~ :, . . : . . .
