Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Bac~ground of the Invention
1. Field of the Invention:
The present invention relates to materlal transport systems and,
more particularly, is directed towards a hydro-transport system for coarse
and fine sollds.
2. Description o the Prior Art:
Delivery of solids to a haulage system often has many variables
such as flow rate, density and product size. Ideally, bulk solids transport
systems would be continuous, never changing in flow rate or consistency.
For most situations this is not the case. Accordingly, conventional haulage
systems must be capable of handllng random flows and variable flow rates.
Hydraulic transport of solids has succeeded primarily where relatively steady-
state flow conditions can be maintained, for example, overland transport of
coal and other fine slurries. For hydraulic haulage to be competitive with
other mgans of transport, such as conveyor belts, rail cars, or trucks, it
must be capable of handling random flows and variable flow rates. Hydraulic
transport of solids under continually varying rates, concentration and
densi*y presents a monumental control problem for a system using conventional
state-of-the-art pumps. Hydraulic transport lines several thousand meters
long with centrifugal pumps appropriately located along the line are subject
to severe water hammer and pump cavltation if the input conditions ~solids
; concentration, solids density and solids or 1uid flow rate) change. Cav-
itation and water hammer can occur when the system contains some sections
with high concentra~ions of solids and others with little or no solids. These
sections of fluid tend to move at different velocities due to inertia effects
causlng sepa~ation of the column and potential pump failure. In addition,
transient effects can be particularly disastrous if the pump at the input
point ventilates or cavitates due to inadequate controi of sump conditions.
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There are many control schemes which can or have been davised to reduce these
problems. Variable speed drives on the pumps and/or intermediate sumps at
each pump location have been used. Both, howeverl require elaborate control
s~ystems to insure that the line dynamics remain within the systems' capability.
Summary of the Inventlon
An object of the present invention is to provide a material trans-
port system which does not suffer from the heretofore mentioned disadvantages
and limitations.
The invention provides a material transport system comprising; ~a)
transport line means; ~b) input station means connected to said transport
line means and conigured to feed a fluid mixture into said transport line
means; ~c) receiving station means connected to said transport line means
and configured to receive said fluid mixture; and ~d) at least one pump
means operatively connected to said transport line means intermediate said
input station means and said receiving station means, said pump means in-
cluding a housing with an internal chamber, said housing including inlet
means, outlet means and vent means that communicate with said chamber, said
înlet means configured to direct a material carried in a fluid external of
said housing into said chamber, rotor means mounted in said housing and con-
strained for rotation within said chamber, said rotor means including blade
means configured to create a 1uid vortex having a ventilated c-ore from said
fluid directed into said chamber through said inlet means when said rotor is
rotated, a mouth o said vortex adjacent said inlet means, and drive means
operatively connected to said rotor means for rotating said rotor at a
sufficiently high rate to create said vortex, said inlet means and said out-
let means connected to said transport line, said material carried by said
ventilated vortex from said inlet means to said outlet means.
From another aspect, the invention provides a pumping device com-
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prising:
(a) a housing with an internal chamber, said housing
including inlet means, outlet means and vent means that communi-
cate with said chamber, said inlet means configured to direct a
material carried in a fluid external of said housing into said
chamber; and
(b) rotor means mounted in said housing for rotation in
said chamber, said vent means communicating with a central portion
of said rotor means and providing free passage of air into and out
of said housing, said rotor means lncluding blade means configured
to create a fluid vortex from said fluid directed into said chamber
through said inlet means, said vortex having a central air core
that is ventilated through said vent means;
(c) said vortex transporting said material at said
inlet means to said outlet means, said fluid constituting a carrier
for said material being transported.
The pumping device is suitable for use as a ventilated
boost pump for a hydraulic transport s~stem which operates at con-
stant speed under variable conditions of transient flow rates and
varying material concentrations. The bladed rotor creates a fluid
vortex with an air core vented to the atmosphere at the center of
the rotor. The diameter of the air core is dependent upon the
back pressure on the pump and varies in order to equalize the
pressure in the housing with the back pressure. The material trans-
ported in the hydraulic transport line is fed into the inlet port,
carried by the fluid vortex to the discharge port and passed into
the transport line.
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Brief Description of the Drawings
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A fuller understanding of the nature and objects of the
present invention will become apparent upon consideration of the
following detailed description taken in connection with the
accompanying drawings, wherein:
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Figure 1 is a side elevation of a pumping devicc embodying the in-
vention;
Figure 2 is a sectional view of the pump of Figure l; and
Figure 3 is a schematic diagram of a material transport system
embodying the invention.
Detailed Description of the Preferred Embodiments
Referring now to the drawings, particularly Figures 1 and 2, there
is shown a pumping device 10 embodying the present invention. In the illus-
trated embodiment, by way of example, pumping device 10 is utilized as a
boost pump in a material transport system 12 in which particulate solids
are carried from an input statlon 14 to a receiving station 16 via a trans-
por~ line 18.
Pump lO includes a housing 20 having a frusto-conical nose 22 and
an internal chamber 24. Nose 22 terminates in an inlet port 26 which com-
municates with transport line 18. Housing 20 is also provided with an out-
let port 28 which communicates with transport line 18. A rotor 30 with one
or more helical blades 32 is mounted in housing and constrained for rotation
within chamber 24 at nose 22. Rotor 30 has a generally conical shape that
tapers inwardly towards inlet port 26. Rotor 30 is mounted on a shaft 34
that is journaled in bearings 36, for example tapered roller bearings, which
provide maximum stiffness. Helical bladc 32 has a gradually expanding
diameter from inlet port 26 towards outlet port 28. A vent 38~ for example
a conduit which is open to the atmosphere, leads to the center of rotor 30.
In an alternative embodiment, housing 20 is vented throl~gh rotor 30.
Blade 32 is configured to create a 1uid vortex 40 having a ven-
tilated core 42. In the illustrated embodiment, by way of example, a slurry
41 en~ering inlet port 26 flows towards chamber 24 at the leading edge of
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blade 32. When rotor 30 is rotated by a driver 44, blade 32 maintains 1uid
vortex 40 and pressurizes housing 20 at outlet port 28. Particulate solids
41 that are fed into inlet port 30 are picked up by blades 32, flung out-
wardly and submerged in vortex 40. The 1uid level in pump lO adjusts
automatically in response to applied downstream pressure in line 18. The
inner radius of vortex 40 contracts when line pressure increases. The
maximum pressure occurs when core 42 of vortex 40 has contracted to the size
of atmospheric vent 38. In response to an increase in back pressure, ven-
tila~ed core 42 contracts or decreases until the pressure in housing 20 is
equalized to the back pressure without any decrease in flow. That is, as
the back pressure increases, core 42 contracts and fluid vortex 40 expands.
Blade 32 engages a greater portion of slurry 41, whereby the pressure within
housing 20 increases until it balances the back pressure. Similarly, in
response to a decrease in back pressure, core 42 expands and the pressure
in housing 20 decreases until the pressures are equalized. The centrifugal
action of slurry 41 prevents introduction of air into transport line 18
as long as vortex 40 is maintained within housing 20.
Rotor 30 is driven by driver 44 through a gear assembly 46 which
includes a gear train 48 having three hel-ical gears 50 mounted in a gear
box 52. A shaft 54 of driver 44 is connected to gears 50 through a flexible
coupling 56 and shaft 34 is connected directly to gears 50. In the illustrated
embodi~ent, by way of exampleJ driver 44 is an 1800 rpm, 400 horsepower
motor and rotor 30 has a diameter of 31.5 inches and rotates at lO00 rpm.
Solids enter rotor inlet 26 at a very low axial velocity and swirl compared
to the peripheral velocity of the rotor inlet at its maximum diameter. The
blade tip speed is approximately 1.8 m/sec. The blade 32 leading edge is
sickle-shaped, with the tip at the orward outermost inlet diameter and
the shank o the sickle attached to the rearward inner most hub o rotor 30.
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Blade 32 is helical and pitched at a shallow angle from a radial plane of
shaft 34. The helical pitch gives a small ratlo or axial flow velocity to
rotor speed, so that over the entire range of flow rates, the solids have
initial trajectories that hit the blade pressure surface at a shallow glanc-
ing angle. Axial impact velocity ls consequently small and thus wear of
the blade surface is min;mized. The sickle-shaped blade 32 reduces the
effect of thc h.igh relative velocity of solids to the blade leading edge.
Impact near the tip is with an edge angled approximately 60 degrees from
the relative velocity and thus impact velocity is half of that for the normal
impact in a typical pump. Bounce energy is approximately 25 percent of that
for normal impact.
Reerring now to Fig. 3, there is shown material transport system
12 in which particulate solids are carried from input station 14 to receiving
station 16. Particulate solids enter input station 14, for example a helical
inducer or a slurry pump, through a line 62 and valve 64. A fluid, for ex-
ample water, is fed into helical inducer 14 via a line 66 and a valve 68.
The slurry discharged from helical inducer 14 is fed through a pair of ven-
tilated boost pumps 10 to receiving station 16. Pumps 10 operate at a con-
stant speed with a constant water flow rate and with varlabLe solid flow
rate. Ventilation of pumps 10 isolates each line section from the next.
~lso, it has been found that transport system 10 handles flows of at least
thirty-five percent change in rate.
Since certain changes may be made in the foregoing disclosures
without departing rom the scope of the invention herein involved, it is
intended that all matter contained in the above description and depicted
in the accompanying drawings be construed in an illustrative and not in a
limiting sense.
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