U.S. patent number 3,649,138 [Application Number 05/016,359] was granted by the patent office on 1972-03-14 for pump apparatus for slurry and other viscous liquids.
This patent grant is currently assigned to Ireco Chemicals. Invention is credited to Robert B. Clay, William A. Doering.
United States Patent |
3,649,138 |
Clay , et al. |
March 14, 1972 |
PUMP APPARATUS FOR SLURRY AND OTHER VISCOUS LIQUIDS
Abstract
A peristaltic pump is operated by squeezing rollers pressing on
an elastic tube supported inside a semicylindrical chamber. The
collapsed tube is reopened by traveling side rollers which press
the tube transversely. This expedites refilling and increases pump
capacity. A surge chamber consisting of an elastic hollow cylinder
housed inside a tubular housing provided with inwardly projecting
annular ribs smooths out both minor and major surges in flow of the
viscous material.
Inventors: |
Clay; Robert B. (Bountiful,
UT), Doering; William A. (Salt Lake City, UT) |
Assignee: |
Ireco Chemicals (N/A)
|
Family
ID: |
21776719 |
Appl.
No.: |
05/016,359 |
Filed: |
March 4, 1970 |
Current U.S.
Class: |
417/477.8;
417/477.5 |
Current CPC
Class: |
F04B
11/0033 (20130101); F04B 43/1253 (20130101) |
Current International
Class: |
F04B
11/00 (20060101); F04B 43/12 (20060101); F04b
043/12 () |
Field of
Search: |
;417/477,476,475,474,900
;418/45 ;92/13.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Sher; Richard
Claims
What is claimed is:
1. A peristaltic pump apparatus for fluids such as slurries and the
like which comprises, in combination, an arcuate channel in a frame
member adapted to receive and house a peristaltic tube, a
collapsible peristaltic tube fitted into said channel and having an
inlet end connectable to a source of material to be pumped, a
rotary carrier mounted concentrically with said channel, roller
mounting means including an eccentric adjustable support secured to
said carrier, a squeeze roller rotatably journaled on said mounting
means for pressing and collapsing said peristaltic tube and thus
forcing its contents forward from said inlet end towards an outlet,
and plural successive pairs of tube opening rollers also carried by
said rotary member and mounted progressively closer together to
assist in opening the collapsed tube after the squeeze roller has
passed along by pushing the edges of said collapsed tube towards
each other in progressive steps thereby to accelerate refilling of
said tube by said by said material from said inlet end.
2. Apparatus according to claim 1 which includes a plurality of
squeeze rollers mounted on said rotary carrier and a plurality of
pairs of said opening rollers following each squeeze roller.
3. Apparatus according to claim 1 which comprises an elastic surge
chamber connected to the outlet of the peristaltic tube to smooth
out the pump output.
4. Combination according to claim 1 which comprises a check valve
connected to the pump outlet and a surge chamber connected to said
check valve.
5. A pump according to claim 1 which includes a surge chamber of
low volume expansion characteristics comprising an axially
extending elastic inner chamber wall member, an outer chamber wall
member coaxial with and spaced annularly from said inner chamber,
and a plurality of spaced rib elements located in the annular space
between said chambers and adapted to limit expansion of the elastic
inner chamber wall member.
6. A pump according to claim 5 wherein the spaced rib elements are
in the form of spaced annular ring elements protruding inwardly
from the outer chamber wall member.
Description
BACKGROUND AND PRIOR ART
Various devices have been proposed in the past for pumping viscous
fluids such as explosive slurries. Such slurries are frequently
very corrosive and abrasive to machinery and pumping operations
involving them have presented serious problems in many instances
because of their reactive solutions and also because of the nature
of the suspended solids they contain. The pumping of blasting
slurries is only one good example of the types of problems
frequently encountered but analogous problems arise with other
viscous liquids.
Slurry blasting agents commonly comprise a gelled liquid media in
which solid particles of metal, such as aluminum, and/or
carbonaceous materials such as ground gilsonite or coal, sugar, and
the like, are suspended. These viscous materials are often quite
heavily loaded with solid particles. In addition to metals and
other fuel particles, granules of undissolved salts, such as
ammonium nitrate, sodium nitrate, and the like, are frequently
included in blasting slurries, although major proportions of these
oxidizer salts usually are in solution. These salts are corrosive
as well as abrasive.
Because of the abrasive character of the solid materials, the
viscous, stringy and sometimes lumpy nature of the whole mixture,
and the difficulty of handling them with more conventional
equipment, there are advantages in using peristaltic pumps. These
pumps are well known in principle, and are used for a variety of
purposes. In pumping thick or viscous slurries, however, cavitation
and other flow hindrance problems arise because of their slow flow
properties. A peristaltic pump necessarily depends on successive
squeezing and opening up of the collapsible tube or channel member
to draw in a continuing supply of the material being pumped. With
heavily loaded or viscous slurries, the rubber tubes or hoses which
are used as tubes or channel members, often do not spring open
rapidly enough to draw in the sluggish flowing material to be
pumped so as to refill the tube. As a result, the pump operates
inefficiently or discontinuously. At best, there tends to be a
pulsating or intermittent type of flow.
An important aspect of the present invention is the provision of a
more positive means by which the slurry may be drawn into the
peristaltic tube. Rollers engaging the side edges of the flattened,
emptied tube are used to open it up into a rounded, or approaching
rounded, position so as to cause the tube to refill with slurry
after the squeegee rollers have passed over it.
Even with peristaltic pumps, there are pressure surges, especially
with the more viscous or heavily loaded slurries. These may be
caused by variations in viscosity, solids loading, flow
irregularities, etc. Pressure pulsations interfere with
manipulations of the delivery hose, as when blasting slurry is
being pumped into boreholes. In some cases they are severe enough
to damage the pumping apparatus and even to burst the delivery
hose. The latter, of course, can involve serious dangers to
operating personnel and in any case it is essential that such
pressure surges be minimized and eliminated as far as possible. The
pumping apparatus often is associated with mixing equipment as is
commonly mounted on a mobile vehicle, such as a truck or trailer
where power equipment is available for driving the pump.
Surge chambers are known in the prior art, including elastic drums,
tubes or cylinders which can yield and thus expand or contract to
accommodate variations in flow velocity and pressure. Various types
of pneumatic pressured surge chambers are known, also. However, it
is most undesirable to have surges accumulate in substantial
volumes. For example, when an operator is filling a borehole with
explosive slurry, it is important for him to be able to start and
stop the flow quickly, e.g. to avoid spillage or overflow. An
expansive surge chamber, where a substantial volume of slurry can
accumulate, makes close control more difficult. It is highly
desirable to be able to smooth out low or high pressure surges
without accumulating relatively large masses of the viscous liquid
in a surge chamber. An important object of the present invention is
to be able to accomplish this.
While the surge chamber of the present invention is particularly
suitable for the peristaltic pump, it is suitable also for use with
reciprocating and other types of pumps where the pulse volume is
not excessive. The surge chamber of the present invention is
designed to accommodate small pressure surges with minimal
volumetric expansion and to accommodate much larger surges in
pressure with relatively little further volume expansion. This is
accomplished by using an elastic tubular chamber member and
surrounding it with spaced annular confining rings. Expansion of
the tube, merely enough to bring its walls into contact with the
rings, requires relatively small pressure increase. Further
expansion, involving stretching of the tube walls between rings, or
beyond rings, requires much larger pressure increments.
SUMMARY
This invention comprises a collapsible tube which forms a flow
chamber for slurry or other viscous or heavily loaded or thickened
liquids, positioned inside a cylindrical or part-cylindrical
surface. Traveling squeeze or squeegee rollers, orbiting around a
central axis which corresponds with the axis of the cylindrical
surface, press the contents of the tube forward through a control
chamber and into a surge chamber. From the surge chamber, the
material may be delivered to a borehole or any other receptacle to
be filled.
The collapsible tube, in the form of a rubber or other elastic
member, tends to reopen after the squeegee rollers have passed over
it. However, the viscous contents may tend to cause the inner walls
to adhere to each other and the sluggish flow properties of the
material being pumped tend to prevent rapid reopening of the tube.
To overcome these tendencies, traveling rollers are provided to
press on the edges of the flattened tube and assist it in
reopening. This expedites considerably the flow of the viscous
liquid into the tube, preparatory to the next flattening action of
the main pressure or squeeze rollers.
The control chamber includes means for determining pressure applied
to the material being pumped, means for releasing the material
through a lateral vent when this is needed, and a "blow-down"
connection, e.g., for admitting air or other fluid to remove
material from the surge chamber and the delivery line or hose.
The surge chamber comprises an expandable tube of rubber or similar
elastic material, preferably rather thick-walled, strong enough to
contain high pressure but elastic enough to expand moderately at
low pressure and more at high pressure. Surrounding this tube with
an annular space between is a strong-walled chamber, provided with
spaced inwardly projecting annular ring elements which almost
contact the expandable tube, when in its normal relatively
undilated condition. On expansion by a moderate pressure pulse, the
tube dilates to contact the rings which largely prevent further
expansion until a much stronger pressure surge forces the tube to
stretch into narrow zones between or beyond the confining annular
rings. Ribs of other shapes may replace rings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side view, with certain parts in section and certain
parts removed, of a preferred embodiment of peristaltic pump,
according to the present invention.
FIG. 2 is a transverse sectional view taken substantially along
line 2--2 of FIG. 1.
FIG. 3 is an enlarged detailed view in section, taken substantially
on line 3--3 of FIG. 1, showing the rollers which help to open up
the peristaltic tube after its contents have been pressed out by
the squeezing rollers.
FIG. 4 is a cross-sectional detail view through the control
chamber, being taken substantially along the line 4--4 of FIG.
1.
FIG. 5 is a fragmentary view showing a side view of the opening
rollers for the peristaltic tube.
DESCRIPTION OF PREFERRED EMBODIMENT
The pump per se consists of a more or less drum-shaped frame member
5 in which a rotating wheel member 6 is mounted on a hollow axle 7
to which it is keyed at 8. The wheel 6 comprises a hub element 9
and integral flange elements 10 and 11. The axle 7 is driven by an
appropriate prime mover shown herein as a motor 12 secured to
extension 13 of axle 7, mounted in antifriction bearings 14 and 15.
A hydraulic motor is preferred for operating this particular unit
in pumping slurry explosives because it offers less hazards than an
electric motor. However, any appropriate prime mover can be used,
e.g., electrical, gasoline driven, etc., depending on the
circumstances and hazards involved.
Wheel 6 carries a pair of squeeze rollers 19 rotatably mounted on
eccentric shafts 20 between the plate flanges 10 and 11. That is to
say that the shafts 20 have reduced end portions 16 and 17 which
are eccentric with respect to the main shafts 20. The ends 17 are
mounted for free rotation in the right flange 11 but the left end
16 (as seen in FIG. 2) of each shaft passes through a bushing 21
concentric and coaxial with the ends 16 and 17, fitted into an
enlarged opening 18 in left flange 10 of main wheel 6. A somewhat
larger disc 22 is keyed or otherwise nonrotatably attached to end
portion 16 so that either eccentric shaft 20 can be rotated to
various positions by rotating disc 22. The latter can be fixed in
the desired position by inserting a locking bolt 23 into the
appropriate one of several holes in disc 22, being screwed into a
threaded opening in the flange 10. By this means, the pressure of
the squeeze or squeegee rollers 19 on the peristaltic tube 24 can
be adjusted as desired. A nut 26 holds the shaft 20 tightly
attached to disc 22.
The peristaltic tube 24 extends from an inlet connection 28 at the
bottom of frame 5 along a horizontal course and then follows the
interior of semicylindrical or drum surface 29 of member 5 to the
top where it extends horizontally to the right to an outlet
connection 30. Surface 29 is wide enough to support or back up the
tube 24 when fully flattened by the rollers 19. Outlet connection
30 is firmly connected to tube 24 and is secured to frame member 5
by an arcuate locking flange 31 which fits into an annular groove
32 in coupling 30.
The tube 24 is a strong elastic hose or cylinder of rubber or
similar deformable and elastic material, which may be suitably
reinforced by fabric or other fibrous material, if desired. Its
elastic properties tend to expand it to a normal round or
near-round open condition after a squeezing roller has passed
by.
The inlet end coupling element 28 preferably is of the
quick-connect type, so that a hose or pipe connection from a supply
tank or a mixing station can readily be attached or detached.
While tube 24 is or tends to be self-reopening, mechanical means
are provided to help and accelerate such reopening after each
passage of a squeeze roller 19. Clamped between bearing brackets 42
and the inner surfaces of flanges 10 and 11 are the shafts 43 on
which edge pressing rollers 40 are mounted for free rotation. See
FIG. 3, also FIG. 5. These rollers are arranged opposite each other
in pairs and two pairs preferably are used to follow each of the
main squeeze rollers 19, as shown in FIG. 1. While two squeeze
rollers 19 are shown in FIG. 1, and this is the preferred
arrangement, the pump will operate with only one, and three or more
may be used, if desired. The side or tube opening rollers, of
course, are used in such numbers and arrangements as required to
open up the tube 24 after each squeezing operation.
The outer end of each roller 40 is beveled, or tapered, as
indicated at 44, so as to engage the tube at a gradual angle and
avoid damage to the tube. The second roller of each pair can be set
inward, if desired, towards the tube 24 with respect to the first
roller so that it further narrows the width of the tube which can
be accommodated between the opposed rollers. The rollers are so
positioned radially with respect to the main axle 7 that they
properly contact the edges of tube 24.
The structure so far described operates as follows: Slurry flows in
through coupling 28 into the collapsible peristaltic tube 24.
Assuming that this tube is open or opening, its expansion creates a
partial vacuum which assists in drawing in the slurry or other
liquid to be pumped from a source of slurry supply, not shown. It
will be understood, of course, that the source of slurry supply
sometimes may be under some hydrostatic pressure, which helps to
cause the material to flow into the tube. Assuming first that the
tube is full or substantially full of slurry, the rotation of wheel
6 around its central axis, as it is driven by shaft 7, rolls the
squeeze rollers 9 around and against the inside of the peristaltic
tube, pressing it against surface 29, FIG. 2, and squeezes the
contents forward in clockwise direction, FIG. 1, through the outlet
connection 30. The flattened tube thereafter is partially reopened
by rollers 40.
From the pump, the slurry passes through outlet connection 30
through an elbow connection 51 and into a check-valve structure 52
which comprises a ball check valve 54 operating against a seat 56.
This valve prevents back-flow of the slurry in case the pump is
stopped, or in case of any other discontinuity in feeding slurry to
the valve.
From check valve 52, another elbow connection 60 carries the slurry
to control chamber structure 62 which has another quick connector
63 similar to connector 28.
As seen in cross section in FIG. 4, control chamber member 62 has a
resilient diaphragm 64 across a top opening 65. Diaphragm 64 is
clamped in place by a ring 66 held by bolts 67. A threaded opening
68 is provided for connecting a signal line 69 (see FIG. 1) which
transmits a pressure reading from the diaphragm to an appropriate
pressure gauge (not shown). By this means, the pressure on the
slurry can be noted and/or recorded.
Member 62 also has a threaded drain or back-flow opening 70 through
which the slurry or other liquid may be discharged or withdrawn
through a suitable line 71 controlled by valve 72. This valve,
normally, is closed. Through a side opening 73, also threaded,
connection may be made to a pneumatic hose or other source of fluid
pressure. By applying each pressure, the residual slurry or liquid
in the outlet line and delivery hose, beyond check valve 54, may be
blown out or discharged.
The upper part of FIGS. 1 and 2 show a surge chamber 80 which
consists of an elastic tubular inner member 81 formed of gum rubber
or other suitable strong elastic material, having not only a high
tensile strength, but being stretchable to at least twice or three
times its normal diameter without rupture. In a typical case, this
tube 81 may be an elastic rubber tube having a wall thickness of
one-eighth to one-fourth-inch or more and being 11/2 to 3 inches or
more in internal diameter. It may be made in various sizes for
different purposes. A length of this tubular material 81 is
connected by clamps 83 to the connecting outlet of chamber 62
mentioned above and to an outlet line 87 through a quick release
connector 85. In normal operation of the pump already described,
pumping of the viscous fluid material forces valve 54 open and the
material flows through the other connection already described.
Thus, the slurry or viscous liquid is pumped through the expansible
conduit 81 and into its outlet line 87. Where this material is an
explosive slurry, the line 87 may constitute or be connected to a
long delivery hose whereby the slurry may be pumped into boreholes
for blasting in large mining operations. As already noted, the pump
can be used for other and analogous materials and is not limited to
use with explosive or other slurries.
Surrounding the tubular conduit 81 but annularly spaced therefrom
at a suitable distance d, is a rigid-walled tube 89. The latter may
be a metal pipe, such as aluminum or steel of sufficient wall
strength to withstand any pressure that can reasonably be expected
from the pump. This surge chamber can be used also with other pumps
or pressure sources connected to its inlet as already
mentioned.
A plurality of ring members 91, preferably three as shown, are
formed inside the rigid-walled conduit 89. They may be separate and
held therein by friction or they may be integral with the wall
member 89. These are preferably cast or formed with the rigid tube
89. However, they may be separate metal rings or other plastic
material than rubber may be used. They are spaced in such a manner
that some expansion of the tube 81 between them may be
accommodated. When the tube 81 is not under substantial pressure,
it preferably does not quite touch the rings 91, although it may be
in light contact therewith, if desired. The spacing between the
rings like their number depends on the magnitude of the pressure to
which the tube 81 is to be subjected, on its material and wall
thickness, and also on the material of which rings 91 are formed.
In normal operation, it may be expected that the tube 81 would be
expanded by a moderate pressure surge into contact with the inner
annular surfaces of the rings 91. Expansion by much higher pressure
is indicated by the dotted line 92, FIG. 1. The surge chamber is
mounted on brackets 94, 95, bolted to the top of frame 5 through
angle foot members 96, 97.
When a strong pressure surge is applied to the tube 81, it expands
to contact the ring members 91. Between adjacent pairs of ring
members it is expanded even further, bulging between the rings to
an extent determined by the pressure and the elasticity and tensile
strength or resilience of the tube material 81. For example, a
surge pressure two to four times as great or even greater than that
required to expand the tube to mere contact with rings 91 is
required to expand the tube significantly into corrugations between
the ring members 91, as shown at 92 in FIG. 1.
In a typical structure tested in accordance with this invention, a
2-inch gum rubber hose, having a wall one-fourth-inch thick, was
first connected inside a 4-inch internal diameter metal pipe, which
was otherwise unobstructed. The connections were substantially as
shown in FIG. 1, with the pipe 89 spaced about 1 inch from the
outer wall of the tube 81 when there was no pressure. Under normal
operation and at moderate pressure, pumping slurry with a
peristaltic type pump, the material flowed smoothly and the
arrangement without rings 91 was satisfactory.
Another model was built using inside a 5-inch pipe a 2 1/4-inch
inside diameter gum rubber tubing with walls one-half inch thick in
their normal, unexpanded condition. At 30 p.s.i. pressure at the
end of a delivery hose, this tubing expanded to fill the casing
which surrounded it. As pressure of 30 p.s.i. was exceeded,
however, there was no further room for expansion and strong surging
occurred in the delivery hose. This surging caused the hose to whip
badly and might have burst a hose of moderate strength.
The system was first tested by pumping water, which is less
compressible than slurry because slurry normally contains some
aeration. The hose pressure on the liquid after passing through the
surge chamber varied only about 2 p.s.i. in surges from an initial
starting pressure of 0 up to about 30 p.s.i.g. pumping pressure.
However as pumping pressure went higher, surges would suddenly jump
to as high as 90 p.s.i., then dropping back to 30 p.s.i. This was
repeated every half revolution of the peristaltic pump. The simple
surge chamber thus described was therefore quite suitable as a
surge absorber at working pressures up to 30 p.s.i. It was
completely inadequate at pressures above 30 p.s.i.
On confining the tube just described with the series of spaced
rings in the manner shown in FIG. 1, the rubber tubing was normally
stretched out into contact with the rings but not greatly beyond
them at a pumping pressure of 30 p.s.i. When stronger surges came
along, the tube 11 was bulged or corrugated between the rings, as
shown in dotted lines 92 but increments of pressure on the delivery
hose were still very low, of the order of 2 or 3 pounds, as
compared with as much as 60 pounds in the case described above.
When pumping water at 30 p.s.i. with the peristaltic pump and surge
chamber of this invention, pressure would sometimes drop to 20
p.s.i., but not go appreciably above 30 p.s.i. When pumping at a
nominal pressure of 80 p.s.i., the pressure normally did not drop
below 60 p.s.i. during the low pressure cycle of the surge.
Table I shows typical results with water:
---------------------------------------------------------------------------
TABLE I
Basic Pump + Pump + Pump + Pump Ck valve ck valve + ck valve +
Surge surge ch. chamber +Rings
__________________________________________________________________________
P.S.I.G. (low) 30 30 30 30 Surge P. -30(1) - 20(2) - 2(3) - 10(4)
P.S.I.G. (high) 90 90 90 90 Surge P. - 90(5) - 70 - 60(6) - 20(7)
__________________________________________________________________________
(1) Gauge needle struck stop peg. (2) Good improvement -- needle
did not strike peg. (3) Nearly constant -- fine for low pressure
pumping. (4) Some fluctuations but not objectionable, considering
pumping pressure. (5) Gauge needle struck stop peg. (6) Very large
pressure fluctuation -- destructive over a period of time. (7) Big
improvement over (6).
With reciprocating type pumps, pressure surges are expected to be
somewhat greater. It is often desirable to use a somewhat larger
expansion chamber of the type shown in FIG. 1. With the structures
shown, the pressure surge may be confined to desired low levels by
adapting the size of the chamber to the volumetric magnitude of
typical surges. It has been pointed out above that large volumetric
expansion is undesirable. With a reciprocating pump, these surges,
of course, are larger than in the case of peristaltic or other
continuous flow devices. A reasonably steady flow at the end of the
hose is desired, and it is desirable, also, to be able to cut off
flow rather quickly without rupturing the tube 81 or the delivery
hose, or doing damage to the pump.
As pointed out above, use of the confining rings around the rubber
tube makes it possible to accommodate surges at operating pressures
of two to four times or more those which are required merely to
expand the tube into contact with the rings. The number of rings
obviously may be varied with different diameters and lengths of
tubing 81. While annular ribs or rings are preferred, such as shown
at 91, it will be understood that ribs which will extend spirally,
or axially may be used. Grids of riblike projections may be used in
some cases. The annular ribs usually control the tube 81 better and
place less strain on it.
The invention described above offers outstanding advantages in
smooth, uniform flow. This is desirable and frequently is very
important in delivering blasting slurry into boreholes. It is
desirable, of course, to be able to control the flow with
reasonable precision, and it is important to avoid whipping and
other malfunctions associated with high pressure surges.
It will be obvious that modifications mentioned above and others
not mentioned may be made by those skilled in the art without
departing from the spirit and purpose of the invention. It is
intended to cover the invention and obvious variations and
modifications as broadly as the prior art permits.
* * * * *