U.S. patent number 3,749,304 [Application Number 05/214,662] was granted by the patent office on 1973-07-31 for method of automatic control of the discharge of a concentrated traction of solid particles dispersed in liquids from a centrifuge rotor.
This patent grant is currently assigned to Ceskoslovenska akademie ved. Invention is credited to Jan Putterlik.
United States Patent |
3,749,304 |
Putterlik |
July 31, 1973 |
METHOD OF AUTOMATIC CONTROL OF THE DISCHARGE OF A CONCENTRATED
TRACTION OF SOLID PARTICLES DISPERSED IN LIQUIDS FROM A CENTRIFUGE
ROTOR
Abstract
The control of discharge valves for the discharge of a
concentrate from the circumference of a centrifuge rotor is
achieved by application of an elastically yieldable body, elongated
and shortened in accordance with the increasing and decreasing
level of the concentrate in the circumferential part of the
centrifuge body.
Inventors: |
Putterlik; Jan (Praha,
CS) |
Assignee: |
Ceskoslovenska akademie ved
(Praha, CS)
|
Family
ID: |
5335220 |
Appl.
No.: |
05/214,662 |
Filed: |
January 3, 1972 |
Foreign Application Priority Data
Current U.S.
Class: |
494/3; 494/37;
137/510 |
Current CPC
Class: |
B04B
1/14 (20130101); Y10T 137/7836 (20150401) |
Current International
Class: |
B04B
1/00 (20060101); B04B 1/14 (20060101); B04b
011/00 () |
Field of
Search: |
;233/19R,19A,2R,2A,46,47R,27,28 ;137/510 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Krizmanich; George H.
Claims
I claim:
1. A method of automatic control of the discharge of a concentrated
fraction of a dispersion of solid particles in a liquid and of a
heavier component in a combination of liquids from a centrifuge
rotor by discharge valves, in dependence on an increasing and
decreasing level of the concentrate, said method comprising the
steps of utilizing for this control changes of longitudinal
dimensions of a solid elastically yieldable body which changes
being caused by the variations in pressure of an increasing and
decreasing level of the concentrate at the circumference of a
centrifuge rotor, simultaneously eliminating the influence of the
treated non-concentrated dispersion occupying the rotor space
centripetally from the concentrate on the elastically yieldable
body by employing an elastically yieldable body having a volume
compressibility corresponding to the volume compressibility of the
liquids.
2. In a centrifuge comprising a rotor for separating a liquid
dispersion of solid particles into a concentrated fraction and a
heavier component, an arrangement for the automatic control of the
discharge of the concentrated fraction comprising a plurality of
discharge openings situated at the circumference of the rotor, each
opening having an associate elastically yieldable body mounted to
move radially within a circumferential area of said rotor defined
by a predetermined upper and lower level of the concentrate, said
elastically yieldable body being made of solid material having a
volume compressibility corresponding to that of said liquid,
thereby to be elongated and shortened in response to changes in
pressure caused the change in concentrate level, and a valve rod
embedded in said elastically yieldable body and reciprocally
extending within said opening to open and close said opening on
movement of said elastically yieldable body.
3. An arrangement as set forth in claim 2 the specific weight of
the elastically yieldable body adjusted to the specific weight of
the dispersion occupying the space of the centrifuge rotor
centripetally from the concentrate.
4. An arrangement as set forth in claim 2, the elastically
yieldable body anchored with its end distant from the rotor axis on
a bracket of the centrifuge rotor and provided on its end closer to
the rotor axis with a strap piece, on which the valve rod is
suspended.
Description
BACKGROUND OF THE INVENTION
This invention relates to a method of automatic discharge of a
concentrated fraction of solid particles dispersed in liquids from
the rotor of a centrifuge by means of discharge valves and to an
arrangement for execution of this method, comprising discharge
valves with valve rods, the position of which is controlled by
automatic regulators.
Actually used methods for the discharge of concentrated fractions
of dispersions of solid particles in liquids by means of
independently operating regulators from a centrifuge rotor are
generally based on the principle of a hydraulic actuation of the
discharge valves.
So far this hydraulic drive of discharge valves is controlled
according to a program, for instance within time intervals, it is
impossible to achieve a perfect conformity of volumes of the
produced and discharged concentrated fraction. In order to prevent
any excessive deposit of the concentrated fraction in the
centrifuge rotor, a larger volume has to be discharged than is
produced so that also a part of a not concentrated fraction is
discharged, reducing thus the efficiency of concentrating.
More progressive methods are based on the dependence of the
hydrostatic pressure on the concentration of the centrifuged
dispersion, or on the changes of volume of the concentraged
fraction at an increasing and decreasing level of the concentrate
in the centrifuge rotor. But these discharge methods still have
drawbacks in a reduced efficiency of the discharge and a reduced
output. This is caused by the circumstance, that a constantly
adjusted hydraulic drive of valve rods is actuated not solely by
pressure or changes of volume of the concentrated fraction, but
also by the pressure of the centrifuged dispersion in the space
centripetally above the concentrate. This pressure varies
considerably due to different irregularities of the operation as
for instance due to variations of passage of the dispersion and of
the counterpressure of the separated fraction, influencing
unfavourably the operation of the valves and the uniformity of
concentration of the dishcharged concentrated fraction.
It is an object of this invention to eliminate these drawbacks and
to provide an automatic control of the discharge of the
concentrated fraction from the centrifuge rotor through discharge
valves in dependence on the increasing and decreasing level of the
concentrate.
It is another object of this invention to eliminate or at least to
substantially reduce the influence of the dispersion which is
centripetally above the concentrate on the discharge of the
concentrate.
SUMMARY OF THE INVENTION
According to this invention the opening and closing of discharge
valves is derived from changes of the shape of an elastically
yieldable body, situated within the range of radial changes of the
lower and upper level of the concentrate in the rotor, which body
is elongated and shortened in the radial direction of the
centrifuge rotor due to increasing and decreasing centrifugal
pressure of the concentrate, whereby the influence of pressure of
the treated dispersion, which is centripetally above the level of
the concentrate, on the elastically yieldable body is eliminated by
using a material for said body, the volume compressibility of which
corresponds to the volume compressibility of liquids.
A notable improvement in the control of discharge valves is thereby
achieved, as due to the circumstance that this operation is derived
solely from pressure differences caused by variations between an
upper and lower level of the concentrate in the centrifuge rotor
and by elimination of influences of any pressure variations of the
dispersion which is centripetally above the concentrate, a
discharge of such a volume of the concentrated fraction is secured,
which corresponds exactly to the produced amount of concentrate.
Another advantage of this control is, that the regulators required
for this control are simple and reliable, using an elastically
yieldable body.
Each of these regulators may comprise an elastically yieldable
body, capable to be extended and shortened in the radial direction
of centrifuge rotor, the volume compressibility of which body
corresponds to the volume compressibility of liquids, which body is
anchored with its end distant from the rotor axis in a bracket of
the centrifuge rotor and which is provided on its end closer to the
rotor axis with a strap piece, on which a valve rod is suspended,
passing through the axis of the elastically yieldable body.
A substantially simple embodiment of the object of this invention
is thus created which is efficient, cheap in manufacture, easy to
maintain and particularly reliable in operation as the major parts
of the regulator consist of the elastically yieldable body with a
valve rod passing through said body.
DESCRIPTION OF DRAWINGS
An exemplary embodiment of the object of this invention is
indicated in the attached drawings, where
FIG. 1 shows a are rotor in a section perpendicularly to its
rotation axis,
FIGS. 2 and 3 ar longitudinal sectional views of regulators showing
a closed and an open valve.
DESCRIPTION OF PREFERRED EMBODIMENT
In FIG. 1 we see a simplified view of part of a centrifuge rotor 1
in a section perpendicularly to the rotation axis of this rotor,
passing through the discharge valves 2. The centrifuge space 3 with
a not shown centrifuge separator, for instance with a disk
separator occupies the central part of the rotor 1, having a supply
and a discharge of the centripetally separated fraction. A
concentration space 4 occupies the circumferential part of the
rotor 1, which space is subdivided into a number of sector
compartments A, B, C, D ... where the concentrated fraction is
settling, the upper level of which concentrated fraction is
indicated by a cylindrical surface of the radius R.sub.1 and its
lower level by a cylindrical surface of the radius R.sub.2. Each
sector compartment A, B ... of the concentrating space 4 terminates
in the radial direction from the rotor axis in a discharge valve 2,
the passage through which is controlled by a regulator 5. Each
regulator 5 consists of an elastically yieldable body 6, a stiff
strap piece 7, a valve rod 8 and a bracket 9.
The elastically yieldable body 6 is with its end distant from the
axis of the centrifuge rotor 1 inserted and anchored in a bracket
9, fixed in the rotor 1. This elastically yieldable body 6 must be
made of a material which is sufficiently elastic so as to return to
its original shape after forces which caused its deformation have
ceased and its volume should depend on pressure in a negligible way
only, similarly as liquids, for which this is a characteristic
property.
It is furthermore advisable that the specific weight of the
material from which the elastically yieldable body 6 is made, is
rather close to the specific weight of the treated dispersion in
the centrifuge space 3. Both these requirements are met for
instance by full rubber, the volume compressibility of which is
practically negligible, which is perfectly elastic and its specific
weight can be adjusted by fillers to the required value. Rubber
made from natural rubber without fillers has for instance a
specific weight about 960 kg m.sup.-.sup.3, whereby the treated
dispersions have generally a higher specific weight and the higher
specific weight can be easily adjusted by fillers.
The automatic control of passage of the concentrate through the
discharge valves 2 according to the described embodiment proceeds
as follows:
The concentrated fraction of the treated dispersion is separated in
the centrifuge space 3 and settles due to centrifugal forces in the
cause of proceeding concentration in the individual sector
compartments A, B ... of the concentrating space 4, which sector
compartments are filled with concentrate within the range of its
upper level and lower level, determined by cylindrical surfaces of
radii R.sub.1 and R.sub.2.
So far the concentrate does not surpass the lower level, determined
by a cylindrical surface of the radius R.sub.2, as indicated for
sector B, the surface of the regulator 5 is exposed to the pressure
of the treated dispersion, surrounding the regulator 5 and
occupying the centrifuge space 3 centripetally above the
concentrate. As the volume compressibility of the elastically
yieldable body 6 is the same as of liquids, this elastically
yieldable body 6 forms an adequate part of the hydraulic content,
represented by the treated dispersion. The centrifugal pressure of
the treated dispersion therefore causes no deformation of this
elastically yieldable body 6 even if it varies due to not uniform
conditions of operation. Therefore so far the level of the
concentrate does not surpass the lower value determined by a
cylindrical surface of a radius R.sub.2 shown in sector B in FIG. 1
and in FIG. 2, the discharge valve 2 remains closed by the valve
rod 8 of the regulator 5. If however the level of the settled
concentrate rises above the lower valve determined by the radius
R.sub.2 it starts to surround the elastically yieldable body 6 of
the regulator 5 and as the specific weight of the concentrate is
larger than that of the treated dispersion, which has been
displaced by this concentrate, it acts on the elastically yieldable
body on their contact places with increased pressure and starts to
compress this elastically yieldable body 6 in direction towards the
valve rod 8 at a simultaneous centripetal elongation into the
centrifuge space 3 containing the treated dispersion having a lower
specific weight and producing therefore a smaller pressure. In
sector C of the concentrating space 4 are in FIG. 1 and FIG. 3
shown conditions how the increasing amount of the concentrated
fraction reached the upper level with the cylindrical surface
having a radius R.sub.1 and how the elastically yieldable body 6
has been thereby deformed.
In this case the settled concentrated fraction with a higher
specific weight surrounds the elastically yieldable body 6 with a
lower specific weight, compresses it perpendicularly to the axis of
the regulator 5 and elongates it by hydrostatic pressure, lifting
thereby simultaneously the stiff strap piece 7 with the suspended
valve rod 8 and opening thus the discharge valve 2.
The opening of the discharge valve 2 introduces a centrifugal
discharge of the settled concentrated fraction from this sector C
from the rotor 1 up to a moment where the concentrate drops to the
lower level determined by cylindrical surface of the radius
R.sub.2, where again conditions indicated in sector B are
prevailing, where the regulator 5 is surrounded by the still not
concentrated dispersion, the centrifugal pressure of which does not
cause any deformation of the elastically yieldable body 6, so that
this body 6 takes its original shape, lowering the stiff strap
piece 7 with the suspended valve rod 8, which closes again the
discharge valve 2. Thus the centrifugal discharge ceases and the
settled concentrated fraction starts again to rise. The described
cycle is constantly repeated.
In the course of the described operation of the regulator 5, axial
movements of the valve rod 8 passing through the elastically
yieldable body take place, as indicated in FIGS. 2 and 3, whereby
both these parts remain in close contact. That is enabled by the
capability of a shearing deformation of the elastically yieldable
body 6 which capability is here fully utilized. A perfect tightness
of the closed mechanism of the regulator 5 is thereby achieved,
where no treated dispersion can enter, so that an operation without
failure is safeguarded.
The object of this invention can be used for separating and
concentrating fine grain dispersions of solid materials in liquids
such as are all suspensions and of heavier components in a
combination of liquids. A possibility of extensive application is
given by the extraordinary simplicity as shown by the described
solution of regulators 5 with elastically yieldable bodies 6.
It is obvious that the same effect could be obtained with another
constructional solution, for instance by suspending the elastically
yieldable body 6 instead by its supporting on the bracket 9.
Similarly some other material can be used for the elastically
yieldable body 6 than rubber, for instance a yieldable container
filled with a liquid.
* * * * *