U.S. patent number 3,858,794 [Application Number 05/454,002] was granted by the patent office on 1975-01-07 for sludge centrifuge.
This patent grant is currently assigned to Alfa-Lavel AB. Invention is credited to Carl-Goran Nilson, Sven Olov Olsson.
United States Patent |
3,858,794 |
Nilson , et al. |
January 7, 1975 |
SLUDGE CENTRIFUGE
Abstract
The centrifugal rotor has a level-maintaining outlet for
clean-separated liquid, a peripheral outlet at the greatest radius
of the inside of the rotor wall, and a conical screw operable in
the rotor to convey separated sludge for discharge from a region of
the rotor remote from said outlets. A valve coacting with the
peripheral outlet is associated with control means operable by the
action of liquid discharged from the level-maintaining outlet to
maintain the valve in condition to close the peripheral outlet, the
valve being operable in response to interruption of the liquid
discharge from the level-maintaining outlet to open the peripheral
outlet and thereby effect removal of deposits on the conveyor
screw.
Inventors: |
Nilson; Carl-Goran (Tullinge,
SW), Olsson; Sven Olov (Farsta, SW) |
Assignee: |
Alfa-Lavel AB (Tumba,
SW)
|
Family
ID: |
20316991 |
Appl.
No.: |
05/454,002 |
Filed: |
March 22, 1974 |
Foreign Application Priority Data
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|
|
|
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Mar 22, 1973 [SW] |
|
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40263/73 |
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Current U.S.
Class: |
494/4; 494/53;
494/57 |
Current CPC
Class: |
B04B
15/06 (20130101); B04B 1/20 (20130101); B04B
11/00 (20130101); B04B 11/04 (20130101); B04B
2001/2083 (20130101) |
Current International
Class: |
B04B
15/06 (20060101); B04B 1/00 (20060101); B04B
11/00 (20060101); B04B 1/20 (20060101); B04B
11/04 (20060101); B04B 15/00 (20060101); B04b
001/10 (); B04b 001/20 () |
Field of
Search: |
;233/3,7,19R,19A,2R,2A,27,28 ;137/204,810 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Krizmanich; George H.
Attorney, Agent or Firm: Hapgood; Cyrus S.
Claims
We claim:
1. In a sludge centrifuge, the combination of a centrifugal rotor
for receiving a sludge-containing liquid to be separated, the rotor
being mounted for rotation about an axis and having a
liquid-level-maintaining outlet for clean-separated liquid, the
rotor also having a peripheral outlet located at the greatest
radius of the inside of the rotor wall, a conical screw mounted in
the rotor coaxially thereof and operable to convey separated sludge
for discharge from the rotor at a region thereof remote from said
outlets, a valve coacting with said peripheral outlet for opening
and closing the same, and control means associated with said valve
and operable by the action of liquid discharged from said
level-maintaining outlet to maintain the valve in condition to
close said peripheral outlet, said valve operating to open said
peripheral outlet in response to interruption of the liquid
discharge from the level-maintaining outlet.
2. The combination of claim 1, comprising also a seat for said
valve and at least partly defining said peripheral outlet, said
control means including a double-armed lever mounted on the outside
of said rotor and carrying said valve on one arm of the lever, the
other arm of the lever being in position to be actuated by liquid
discharged from the level-maintaining outlet.
3. The combination of claim 1, comprising also a seat for said
valve and located at the outer end of said peripheral outlet, said
valve being movable radially to and from said seat and having a
radially outer end, said control means forming a channel provided
with a drain hole and leading from the level-maintaining outlet to
said outer end of the valve.
4. The combination of claim 1, in which said control means include
a vortex fluidistor located radially outside said peripheral outlet
and into which said peripheral outlet opens, the fluidistor having
a generally circular cavity and a passage leading from the
level-maintaining outlet and opening tangentially into said
cavity.
5. The combination of claim 1, comprising also a seat for said
valve and through which said peripheral outlet opens in a direction
parallel to said rotation axis, said control means forming a
chamber in which the valve is reciprocable parallel to said axis,
said chamber having an inner end adjacent said peripheral outlet
and having an outer end remote from the peripheral outlet, said
control means also forming a channel leading from the
level-maintaining outlet to said outer end of the chamber, each end
of said chamber having a drain hole.
Description
The present invention relates to a sludge centrifuge equipped with
a liquid-level-maintaining outlet for clean-separated liquid as
well as with a conical screw coaxial with the centrifuge rotor and
feeding separated sludge to an outlet located closer to the axis of
rotation of the centrifuge rotor than said liquid outlet, the
centrifuge also having an outlet which can be opened intermittently
and is located at the greatest radius of the inside of the wall of
the centrifuge rotor. A centrifuge of this kind is disclosed in the
Swedish patent specification 310,624.
A centrifuge of the above-mentioned kind is of special interest for
the separation of a sludge-containing liquid which, in addition to
sludge with a higher specific gravity than the liquid, contains
sludge with a lower specific gravity than the liquid. As in the
case of certain waste waters, this lighter sludge may consist of
sticky substances, such as fat, which deposit on the screw and fill
its threads, whereby a further running of the centrifuge is made
impossible. By opening the outlets which can be opened
intermittently and interrupting the supply of the liquid to be
separated, but otherwise allowing the centrifuge to run, the rotor
can be emptied of liquid through these outlets. After the liquid
has discharged from the rotor, the deposits on the screw are thrown
outwardly by the centrifugal force and fed by the screw to the
sludge outlet.
In the centrifuge according to the Swedish patent specification
310,624, it is necessary for removal of deposits on the screw to
take steps to open the outlets through which the rotor is emptied
of liquid, in addition to an interruption of the supply of the
liquid to be separated. The present invention relates to an
improvement of this centrifuge whereby the discharge of liquid from
the rotor is effected automatically by an interruption of the
supply to the centrifuge of the liquid to be separated.
Consequently, in this way an appreciable simplification of the
operation of the centrifuge is effected. More exactly, the new
centrifuge is characterized by a valve inserted in said outlet
which can be opened intermittently, said valve being arranged to be
kept closed under the action of liquid discharged from the
levelmaintaining outlet.
A number of different embodiments are possible within the scope of
the present invention. A first such embodiment is characterized in
that the valve-controlled outlet has a radially outer opening
forming a valve seat and that a double-armed lever, arranged on the
outside of the centrifuge rotor, is journalled so that a valve body
carried by one end of the lever is movable radially relatively to
said valve seat, the other end of the lever being arranged to be
actuated by liquid discharged from the level-maintaining
outlet.
A second embodiment is characterized in that the valve-controlled
outlet has a radially outer opening forming a valve seat for a
radially movable valve body and that a channel, provided with a
drainhole, leads from the level-maintaining outlet to the radially
outer end of the valve body.
A third embodiment is characterized in that the valve-controlled
outlet opens into a vortex fluidistor, located radially outside
this outlet, the tangentially arranged inlet for the control liquid
of the fluidistor communicating with the level-maintaining
outlet.
A fourth embodiment is characterized in that the valve-controlled
outlet has an axially directed, outer opening forming a valve seat
for a valve body which is axially movable in a chamber as a piston,
the chamber thus having an axially inner and an axially outer end,
there being a channel leading from the level-maintaining outlet to
the outer end of the chamber, and each end of the chamber being
provided with a drainhole.
The invention is described more in detail below with reference to
the accompanying drawings in which
FIGS. 1 through 4 are axial sectional views of parts of four
different embodiments, chosen by way of example, of the rotor of
the present centrifuge. Corresponding details in the different
figures have the same reference numerals.
In FIG. 1, reference numeral 1 designates a centrifuge rotor having
a horizontal axis of rotation 2. A conventional conical screw 3
feeds sludge, deposited on the inside of the rotor, to the left to
the usual outlet (not shown) which is located closer to the axis of
rotation than an outlet 4 for clean-separated liquid. The liquid to
be separated is supplied through the usual inlet (not shown). The
outlet 4 is formed by a hole located eccentrically in a disc 5
which is inserted in the right-hand end wall of the rotor and which
is adjustable by being rotated. Thus, the distance of the liquid
outlet 4 from the axis of rotation 2 can be varied in a desired
manner. At the greatest radius of the inside of the rotor there is
a hole 6 passing radially through the rotor wall. A double-armed
lever 7 is journalled on a bracket 7a on the outside of the rotor
wall. The left-hand end of the lever carries a valve body 8, the
hole 6 opening into a valve seat for the valve body 8. The
right-hand end of the lever has the shape of a scoop 9, which
catches liquid discharging from the overflow outlet 4. As will be
readily understood, the valve 6, 8 is kept closed as long as liquid
discharges through the overflow outlet 4 (i.e., as long as rotor 1
continues to receive a supply of the liquid to be separated).
When it is desired to clean the screw 3, the liquid supply to the
rotor is interrupted without the centrifuge being stopped. Liquid
then ceases to act upon the scoop 9, and the valve 6, 8 opens under
the pressure of the liquid 10 present in the rotor. The latter is
then emptied of all liquid through the hole 6, and the fat or
similar sticky, light material stuck in the threads of screw 3 is
thrown from the latter by centrifugal force and hits the inside of
the rotor's peripheral wall, whence the screw feeds the material to
the sludge outlet. After this cleaning has taken place, the supply
to the rotor of the liquid to be separated is resumed, the supply
rate appreciably exceeding the discharge rate which is possible
through the hole 6.
In FIG. 2, 11 designates an annular chute arranged on the outside
of the end wall and catching a part of the liquid discharging from
the overflow outlet 4. The main part of the liquid from the outlet
4 flows over the edge of the chute 11. A channel 12 leads from this
chute to the radially outer end of a radially guided valve body 13,
for which the hole 6 serves as a valve seat. The channel 12 has a
drain hole 14. A recess 16 is provided in the annular member 15 in
which the channel 12 and chute 11 are formed. As long as the supply
of the liquid to be separated is uninterrupted, the valve 6, 13 is
kept closed by means of the liquid pressure acting against the
radially outer end of the valve body 13. When the supply of the
liquid to be separated is interrupted, the supply of liquid to the
chute 11 ceases and the channel 12 is emptied of liquid through the
drain hole 14. The valve body 13 is thus thrown radially outwards
by the centrifugal force, the liquid 10 being discharged through
the hole 6 and the recess 16. The screw 3 therefore becomes
cleaned, as previously described.
FIG. 3 shows a variation of the embodiment according to FIG. 2, in
that the valve body in FIG. 2 has been replaced by a vortex
fluidistor whose cavity 17, as seen in radial direction, has a
circular shape. The channel 12 opens tangentially into the
fluidistor, as indicated at 18, and supplies control liquid from
the chute 11. As long as control liquid is supplied to the
fluidistor from the chute 11, the whirl formation in the fluidistor
cavity 17 generates such a great flow resistance against discharge
of liquid through the hole 6 that the outflow through the latter is
small. However, as soon as the supply of the liquid to be separated
is interrupted, the chute 11 is drained through the passage 12, 18,
14, whereupon the whirl movement in cavity 17 ceases and the flow
resistance in the passage 6, 17, 14 is strongly reduced so that the
centrifuge rotor 1 is emptied through the hole 14.
In FIG. 4, 19 designates a valve housing secured to rotor 1 and in
which there is arranged an axially movable valve body 20 provided
with a labyrinth seal. In the rotor end wall there is arranged an
axial channel 21 in which a tube 22 is inserted, this tube serving
as a valve seat for the valve body 20. The chute 11 is like the
chutes 11 in FIGS. 2 and 3. The space 23 in which the valve body 20
moves has a liquid inlet 24 from the chute 11 and two drain holes
25 and 26, one at each end of the space 23. As long as liquid flows
into the space 23 from the chute 11, the valve 20 - 22 is kept
closed, since the right-hand end of the valve body 20 has a greater
surface area acted upon by liquid than its left-hand end. However,
as soon as the supply of liquid from the chute 11 ceases, the valve
body 20 is pressed to the right and the liquid 10 is emptied
through the drain hole 25.
It will be understood that screw 3 is rotated at a different speed
than the rotor 1, in order to convey the separated sludge to the
left toward the sludge outlet. Those details of the centrifuge not
illustrated are well known in the art, as disclosed, for example,
in U.S. Pat. Nos. 3,447,742 and 3,506,187 dated June 3, 1969, and
Apr. 14, 1970, respectively.
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