U.S. patent application number 10/485976 was filed with the patent office on 2005-03-10 for pulp pump.
Invention is credited to Algers, Bengt, Baniameri, Amir, Danielsson, Peter.
Application Number | 20050053496 10/485976 |
Document ID | / |
Family ID | 20284996 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050053496 |
Kind Code |
A1 |
Danielsson, Peter ; et
al. |
March 10, 2005 |
Pulp pump
Abstract
Centrifugal pumps for pumping a pulp suspension and conducting
gas away from the pulp suspension are disclosed including a pump
housing having an inlet and an outlet, a rotary shaft, an impeller
mounted on the rotary shaft within the pump housing, the impeller
including a hub and pump blades extending outwardly from the hub, a
wheel disk adjacent to the impeller so that the pump blades extend
outwardly along the wheel disk, a vacuum impeller within the pump
housing behind the wheel disk and including a vacuum pump housing,
vacuum impeller blades, a seal for sealing the vacuum pump housing
to the rotary shaft, the vacuum pump housing including a suction
port for drawing gas into the vacuum pump housing and an exhaust
port for expelling gas therefrom.
Inventors: |
Danielsson, Peter;
(Fagervik, SE) ; Algers, Bengt; (Nol, SE) ;
Baniameri, Amir; (Goteborg, SE) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,
KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Family ID: |
20284996 |
Appl. No.: |
10/485976 |
Filed: |
February 5, 2004 |
PCT Filed: |
July 8, 2002 |
PCT NO: |
PCT/SE02/01358 |
Current U.S.
Class: |
417/423.14 ;
417/423.1 |
Current CPC
Class: |
F04D 29/128 20130101;
D21D 5/26 20130101; F04D 9/041 20130101 |
Class at
Publication: |
417/423.14 ;
417/423.1 |
International
Class: |
F04B 017/00; F04B
035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2001 |
SE |
0102678-0 |
Claims
1-3. (canceled).
4. A centrifugal pump for pumping a pulp suspension and conducting
gas away from said pulp suspension, said centrifugal pump
comprising a pump housing including an inlet for said pulp
suspension and an outlet for said pumped pulp suspension, a rotary
shaft, an impeller mounted on said rotary shaft within said pump
housing, said impeller including a hub, and a plurality of pump
blades extending outwardly from said hub, a wheel disk adjacent to
said impeller whereby said pump blades extend outwardly along said
wheel disk, a vacuum impeller disposed within said pump housing
behind said wheel disk, said vacuum impeller including a vacuum
pump housing, a plurality of vacuum impeller blades disposed within
said vacuum pump housing, and a seal for sealing said vacuum pump
housing to said rotary shaft, said vacuum pump housing including a
suction port for drawing gas into said vacuum pump housing and an
exhaust port for expelling gas from said vacuum pump housing.
5. The centrifugal pump of claim 4 including a channel connecting
said suction port with said exhaust port, and a valve disposed
within said channel for controlling the vacuum in said vacuum pump
housing.
6. The centrifugal pump of claim 4 wherein said vacuum pump housing
includes a first side adjacent to said impeller and a second side
distal from said impeller, said suction port and said exhaust port
being disposed on said first side of said vacuum pump housing, said
seal being disposed on said second side of said vacuum pump housing
and including a sealed housing and a liquid inlet connected to said
sealed housing, said sealed housing communicating with said vacuum
pump housing to supply said liquid to said vacuum pump housing.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a centrifugal pump for pulp
suspensions of lignocellulosic material. More particularly, the
present invention relates to a pump where gas, such as air, can be
separated from the pulp in the pump.
[0002] Gas following along with the pulp creates problems during
pumping of pulp by centrifugal pumps. The gas in the pulp forms
bubbles, which are accumulated in front of the impeller and thereby
deteriorate the capacity of the pump. This problem can be overcome
by evacuating the gas from the space in front of the impeller, for
example by means of vacuum pumps such as the liquid-ring pump type.
Such a pump can be a separate vacuum pump, the suction pipe of
which is connected to the sealing space of the pulp pump, or it can
be formed with a separate vacuum impeller in the form of a
liquid-ring impeller, which is mounted on the shaft of the pulp
pump, so that for both impellers a common operation is
obtained.
[0003] In cases where a separate vacuum pump is used, the pulp pump
becomes relatively complicated and expensive, because the system
comprises more components compared to a pulp pump, where the vacuum
impeller is mounted on the shaft of the pulp pump.
[0004] Swedish patent specification No. 502,127 and European patent
specification No. 298,949 describe embodiments of pulp pumps where
the vacuum impeller is mounted on the shaft of the pulp pump.
During, for example, control of the capacity of the vacuum pump by
adjustable throttling or resetting the eccentricity of the vacuum
pump housing, as shown in Swedish patent specification No. 502,127,
several movable parts are required in the pump housing. This
requires more or less extreme designs, with the concurrent risk of
faulty functioning. The maintenance will also thus be more
complicated and expensive. In cases when the vacuum pump is
controlled by means of additional air, as shown in European patent
specification No. 298,949, a great amount of air is supplied to a
pump system, with the intention being that air should be removed
therefrom.
[0005] The present invention implies that the aforesaid problems
can be eliminated. The manufacture and maintenance costs for the
pulp pump, for example, can be reduced. The need of liquid for the
operation is decreased, and control and sealing of the vacuum pump
can be carried out more simply. The need of air to be added to the
pump can also be reduced substantially.
SUMMARY OF THE INVENTION
[0006] In accordance with the present invention, these and other
objects have been realized by the invention of a centrifugal pump
for pumping a pulp suspension and conducting gas away from the pulp
suspension, the centrifugal pump comprising a pump housing
including an inlet for the pulp suspension and an outlet for the
pumped pulp suspension, a rotary shaft, an impeller mounted on the
rotary shaft within the pump housing, the impeller including a hub,
and a plurality of pump blades extending outwardly from the hub, a
wheel disk adjacent to the impeller whereby the pump blades extend
outwardly along the wheel disk, a vacuum impeller disposed within
the pump housing behind the wheel disk, the vacuum impeller
including a vacuum pump housing, a plurality of vacuum impeller
blades disposed within the vacuum pump housing, and a seal for
sealing the vacuum pump housing to the rotary shaft, the vacuum
pump housing including a suction port for drawing gas into the
vacuum pump housing and an exhaust port for expelling gas from the
vacuum pump housing. In a preferred embodiment, the centrifugal
pump includes a channel connecting the suction port with the
exhaust port, and a valve disposed within the channel for
controlling the vacuum in the vacuum pump housing.
[0007] In accordance with another embodiment of the centrifugal
pump of the present invention, the vacuum pump housing includes a
first side adjacent to the impeller and a second side distal from
the impeller, the suction port and the exhaust port being disposed
on the first side of the vacuum pump housing, the seal being
disposed on the second side of the vacuum pump housing and
including a sealed housing and a liquid inlet connected to the
sealed housing, the sealed housing communicating with the vacuum
pump housing to supply the liquid to the vacuum pump housing.
[0008] In accordance with the present invention, the pulp pump is
formed so that the suction port and exhaust port of the vacuum pump
housing are in controllable connection with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention is described in greater detail in the
following detailed description, with reference to the accompanying
Figures in which:
[0010] FIG. 1 is a side, elevational, cross-sectional view of a
centrifugal pump according to the present invention; and
[0011] FIG. 2 is a side, elevational, schematic view of the
coupling between gas inlet and gas outlet to and from the vacuum
pump in accordance with the present invention.
DETAILED DESCRIPTION
[0012] The centrifugal pump shown in FIG. 1 comprises a pump
housing 10 with an inlet 11 and an outlet 12 for the pulp
suspension. Such pumps are used at relatively high pulp
concentration, for example from about 6% to 18%. On a rotary shaft
13 in the pump housing 10 an impeller 14 is mounted, the pump
blades 15 of which extend from a hub 16 outward along a wheel disk
17. On the rear side of the wheel disk 17 back blades 18 are
located. The wheel disk 17 is further formed with openings 19 for
the discharge of gas collected in front of the impeller.
[0013] Behind the impeller 14 a vacuum impeller with vacuum
impeller blades 20 is located, which impeller is surrounded by a
vacuum pump housing 21. This vacuum pump housing 21 comprises an
outer cylindrical wall 22, a rear wall 23 and a front wall 24. The
cylindrical wall 22 is eccentric in relation to the vacuum impeller
blades 20, so that a liquid ring pump is formed. In the front wall
24 a suction port 25 for gas and an exhaust port 26 for gas are
located. These ports, 25 and 26, are placed at a distance from each
other in the circumferential direction disposed for gas suction
into the vacuum pump housing and gas exhaust from the vacuum pump
housing, respectively. This effect is brought about in a manner
which is known by the rotation of the vacuum impeller blades and
the volume variation in the circumferential direction of the vacuum
pump housing as a consequence of the eccentric position of the
cylindrical wall 22.
[0014] The exhaust port 26 communicates with a chamber 27 for gas
evacuation through a gas outlet 28. On the rear side of the
impeller 14 between the wheel disk 17 and front wall 24 of the
vacuum pump housing a gas passage 29 for communication between the
openings 19 in the wheel disk 17 and suction port 25 is
located.
[0015] Behind the rear wall 23 a sealing housing 30 with a shaft
sealing 31 for the vacuum pump and pulp pump is located. The
sealing is intended for the flow-through of liquid, which is
supplied by a liquid inlet 32. The sealing housing 30 also
communicates with the vacuum pump housing 21 for the supply of
liquid from the sealing to the vacuum pump.
[0016] By using a common liquid inlet 32 for the sealing 31 and
vacuum pump housing 21, the liquid amount can be restricted without
problems. Only one liquid connection is required. The pressure
difference arising between the sealing housing 30 and vacuum pump
housing implies a barrier for flow in the opposite direction, i.e.
only clean water will be found in the surrounding of the
sealing.
[0017] The suction port 25 and exhaust port 26 of the vacuum pump
housing are in controllable connection with each other, for example
by means of an overflow channel 35 with a device 36 for vacuum
control. By means of this control device 36 the connection between
the suction and exhaust side can be controlled without the use of
air addition from the outside in order to prevent the pulp
suspension from being sucked into the vacuum pump, if the pressure
would be much too low. Instead of air addition from the outside a
portion of the air is thus used which already has been sucked out
of the pulp pump for the control. This implies a pump system with
less air flows. At the same time the design is simpler and easier
to control. The control device 36 can be a valve in the overflow
channel 35, for example of the on/off type, a throttle valve or the
like. The control device can be controlled by signals from the
system in a suitable way which is known per se.
[0018] The present invention, of course, is not restricted to the
embodiment shown, but can be varied within the scope of the claims
with reference to the description and Figures.
[0019] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *