Title: Hydraulic turbine draft tube with enhanced dissolved oxygen
Abstract: A hydraulic turbine has a gas distribution manifold mounted to an inside wall of a draft tube downstream from a turbine runner. The gas distribution manifold extends at least substantially around the first inside wall of the draft tube. The gas distribution manifold has a plurality of gas outlet ports for discharging oxygen into the water as the oxygen containing gas passes there around. An oxygen containing gas supply extends along a person access passageway and through the wall of the draft tube into the gas distribution manifold adjacent a man hole door.
Patent Number: 6,971,843 Issued on 12/06/2005 to Desy, et al.
| Inventors:
|
Desy; Normand (Laval, CA);
Grenier; Roger (St-Eustache, CA)
|
| Assignee:
|
General Electric Canada Inc. (Mississauga, CA)
|
| Appl. No.:
|
602601 |
| Filed:
|
June 25, 2003 |
| Current U.S. Class: |
415/116; 60/696; 261/37; 261/91; 261/93; 261/DIG.75 |
| Intern'l Class: |
F01D 025/30 |
| Field of Search: |
415/115-116,110-112,170.1,173.6,173.1,173.3,173.5,174.2,174.5,1682-1684
60/686,689,696
261/37,91,93,DIG.75
|
References Cited [Referenced By]
U.S. Patent Documents
| 2300748 | Nov., 1942 | Rheingans.
| |
| 3185440 | May., 1965 | Hullmann et al.
| |
| 3724966 | Apr., 1973 | Sproule.
| |
| 4142825 | Mar., 1979 | Koeller.
| |
| 4142826 | Mar., 1979 | Koeller.
| |
| 4146351 | Mar., 1979 | Koeller.
| |
| 4780051 | Oct., 1988 | Fisher, Jr.
| |
| 5823740 | Oct., 1998 | Cybularz et al.
| |
| 5879130 | Mar., 1999 | Beyer et al.
| |
| 5896657 | Apr., 1999 | Beyer et al.
| |
| 5924842 | Jul., 1999 | Beyer et al.
| |
| 5924844 | Jul., 1999 | Cybularz et al.
| |
| 5941682 | Aug., 1999 | Cybularz et al.
| |
| 6095749 | Aug., 2000 | Beyer et al.
| |
| 6155783 | Dec., 2000 | Beyer.
| |
| 6247893 | Jun., 2001 | Beyer et al.
| |
| 6454533 | Sep., 2002 | Beyer.
| |
| Foreign Patent Documents |
| 2809139 | Nov., 2001 | FR.
| |
| 1263902 | Oct., 1986 | SU.
| |
Primary Examiner: Verdier; Christopher
Claims
1. A hydraulic turbine adapted to introduce oxygen into water flowing through
a water passageway of the turbine, the turbine comprising:
a rotatably mounted runner;
a draft tube extending downstream of the runner, the draft tube having a first
inside wall;
a gas distribution manifold mounted to, and extending at least substantially
around, the first inside wall of the draft tube, and the gas distribution manifold
having a plurality of gas outlet ports distributed around the gas distribution
manifold; and,
an oxygen containing gas supply passing through the first inside wall of the
draft tube and being connected to the gas distribution manifold for supplying an
oxygen containing gas to the gas distribution manifold whereby the oxygen containing
gas flows around the gas distribution manifold within the draft tube and is discharged
from the plurality of gas outlet ports of the gas distribution manifold into the
water passageway to increase dissolved oxygen in the water discharged from the
water passageway.
2. The hydraulic turbine of claim 1 wherein the oxygen containing gas is ambient air.
3. The hydraulic turbine of claim 2 wherein the ambient air is pressurized.
4. The hydraulic turbine of claim 1 wherein the oxygen containing gas is supplied
under pressure.
5. The hydraulic turbine of claim 1 wherein each of the gas outlet ports has
a shroud covering providing a venturi arrangement responsive to flow of water along
the water passageway.
6. The hydraulic turbine of claim 1 wherein the gas distribution manifold comprises
a second inside wall spaced from the first inside wall of the draft tube and a
downstream inclined wall angled and extending from the second inside wall to the
first inside wall of the draft tube, and wherein the plurality of gas outlet ports
are located in the downstream inclined wall providing a venturi arrangement responsive
to flow of water along the water passageway over the first and second inside walls.
7. The hydraulic turbine of claim 1 wherein the gas distribution manifold includes
baffles for controlling the volume of oxygen containing gas into the water passageway
around the gas distribution manifold.
8. The hydraulic turbine of claim 1 positioned in a concrete foundation and wherein
the draft tube further includes a man hole door permitting access through the first
inside wall into the draft tube, a person access passageway leading to the man
hole door located in the concrete foundation and the oxygen containing gas supply
extending through the person access passageway and through the first inside wall
of the draft tube adjacent the man hole door and into the gas distribution manifold.
9. The hydraulic turbine of claim 8 wherein the gas distribution manifold extends
around the first inside wall of the draft tube except for a portion of the first
inside wall where the man hole door is positioned.
10. The hydraulic turbine of claim 1 wherein a wall portion of the first inner
wall of the draft tube forms part of the gas distribution manifold.
11. The hydraulic turbine of claim 6 wherein a wall portion of the first inner
wall of the draft tube forms part of the gas distribution manifold.
12. A turbine installation configured to introduce oxygen into water passing
through a water passageway of a turbine, the installation comprising:
a stationary casing for containing the turbine and defining the water passageway,
the casing extending from an upstream inlet to a downstream outlet and including
a head cover and a discharge ring;
a runner rotatably disposed in the casing so that water flowing therethrough
impinges on the runner;
a draft tube extending downstream of the runner, the draft tube having a first
inside wall diverging outwardly in the downstream direction of water passing through
the draft tube;
a gas distribution manifold mounted to, and extending at least substantially
around, a wall portion of the first inside wall of the draft tube, the gas distribution
manifold having a plurality of gas outlet ports spaced around the gas distribution
manifold; and,
an oxygen containing gas supply passing through the first inside wall of the
draft tube and being connected to the gas distribution manifold for supplying an
oxygen containing gas whereby the oxygen containing gas flow around the gas distribution
manifold and is discharged from the plurality of gas outlet ports into the water
passageway to increase dissolved oxygen in the water discharged from the water passageway.
13. The turbine installation of claim 12 wherein the oxygen containing gas is
ambient air.
14. The turbine installation of claim 13 wherein the ambient air is pressurized.
15. The turbine installation of claim 12 wherein the oxygen containing gas is
supplied under pressure.
16. The turbine installation of claim 12 wherein each of the gas outlet ports
has a shroud covering for providing a venturi arrangement responsive to flow of
water along the water passageway.
17. The turbine installation of claim 12 wherein the gas distribution manifold
comprises a second inside wall spaced from the first inside wall of the draft tube
and a downstream inclined wall angled and extending from the second inside wall
to the first inside wall of the draft tube, and wherein the plurality of gas outlet
ports are located in the downstream inclined wall providing a venturi arrangement
responsive to flow of water along the water passageway over the first and second
inside walls.
18. The turbine installation of claim 12 wherein the gas distribution manifold
includes baffles for controlling the volume of oxygen containing gas into the water
passageway around the gas distribution manifold.
19. The turbine of claim 12 positioned in a concrete foundation and wherein the
draft tube further includes a man hole door permitting access through the first
inside wall into the draft tube, a person access passageway leading to the man
hole door located in the concrete foundation and the oxygen containing gas supply
extending through the person access passageway and through the first inside wall
of the draft tube adjacent the man hole door and into the gas distribution manifold.
20. The turbine installation of claim 19 wherein the gas distribution manifold
extends around the first inside wall of the draft tube except for a portion of
the first inside wall where the man hole door is positioned.
21. The turbine installation of claim 12 wherein the wall portion of the first
inner wall of the draft tube forms part of the gas distribution manifold.
22. The turbine installation of claim 17 wherein the wall portion of the first
inner wall of the draft tube forms a part of the gas distribution manifold.
Description
FIELD OF THE INVENTION
The present invention relates to a hydraulic turbine and, in particular, to a
draft tube for a turbine adapted to increase the dissolved oxygen content of water
discharged from the turbine.
BACKGROUND OF THE INVENTION
The oxygen levels of water discharged from hydraulic turbines used in hydroelectric
installations have been known to provide an environmental problem due to the discharged
water having relatively low levels of dissolved oxygen. The problem is more predominant
in the summer months. During the summer months, thermal stratification of water
in an upstream water reservoir creates warmer water near the surface having relatively
high dissolved oxygen and a colder water near the bottom of the reservoir having
relatively lower dissolved oxygen. Because the water utilized by the turbines is
usually taken from the bottom of the reservoir, this water presents a potentially
environmental hazard when discharged downstream by the turbines.
In the building of new hydroelectric installations and the refurbishing of existing
hydroelectric installations, there is an opportunity to improve the level of dissolved
oxygen in the water by introducing oxygen to the water as it passes through the
turbine. It is known to admit air through one or more runner blades in the turbine
as disclosed in U.S. Pat. No. 5,879,130 issued Mar. 9, 1999; U.S. Pat. No. 5,896,657
issued Apr. 27, 1999; U.S. Pat. No. 5,924,842 issued Jul. 20, 1999; U.S. Pat. No.
6,155,783 issued Dec. 5, 2000; U.S. Pat. No. 6,247,893 issued Jun. 19, 2001, and
U.S. Pat. No. 6,454,533 issued Sep. 24, 2002. However, each of these turbines requires
introducing air through at least one of the moveable turbine runner blades. This
requires complex blade manufacture and the introduction of air through a moving part.
It is also known from U.S. Pat. No. 4,142,825 issued Mar. 6, 1979; U.S. Pat.
No.
4,142,826 issued Mar. 6, 1979 and U.S. Pat. No. 4,146,351 issued Mar. 27, 1979,
to admit air through the foundation of the draft tube. The purpose of this air
admission however, is to quiet pressure pulsations and cavitation problems caused
by high or part load rope vortices within the draft tube. A finite number of shroud
covered air outlets extend through the draft tube to provide the air admission.
These patents, however are not concerned with an even distribution of oxygen gas
into the draft tube to increase dissolved oxygen in the water passing through the
turbine. Further, because the draft tube is usually embedded in a concrete foundation,
providing multiple air supply lines in embedded concrete is cumbersome and is not
well suited for use in an existing turbine to be refurbished.
It is also known from U.S. Pat. No. 5,941,682 issued Aug. 24, 1999 to enhance
oxygen content in water passed through a turbine by having a gas chamber substantially
surrounding an upper peripheral portion of the draft tube and by having a continuous
gas discharge slot that extends about an entire circumference of the water passage.
Gas is discharged from the slot under pressure into the water passage so that the
level of dissolved oxygen in the water discharged from the turbine is increased.
To utilise this arrangement in existing turbine installations, however, involves
costly removal of an upper portion of the draft tube along with a 360° surrounding
portion of the concrete from the foundation. Further, the patent recites the gas
plenum chamber contains gas at a higher pressure than the local water pressure
adjacent the slot whereby the chamber remains substantially free of water and gas
is discharged from the slot into the water passageway.
Accordingly, there is a need for a relatively less labour intensive
and less complex draft tube construction that permits for the introduction of oxygen
into the water passing through the turbine.
SUMMARY OF THE INVENTION
The present invention relates to a hydraulic turbine adapted to introduce oxygen
into the water flowing through the water passageway of the turbine. This is accomplished
by a gas distribution manifold mounted to the inside wall of the draft tube where
the gas distribution manifold has a plurality of gas outlet ports spaced around
the gas distribution manifold. An oxygen containing gas supply passes through the
draft tube wall to supply an oxygen containing gas for distribution by the gas
distribution manifold there around and out through the gas outlet ports into the
water passage.
The present invention has the advantage that the gas distribution manifold may
be readily mounted to the inside of the draft tube without requiring any alteration
in the concrete foundation supporting the draft tube. Further, the gas distribution
manifold, from a labour installation perspective, is relatively easy to install
and requires minimal changes to the draft tube wall for supplying oxygen containing
gas to the gas distribution manifold. Further, the gas distribution manifold circulates
or distributes the oxygen containing gas about the manifold and out the outlet
ports to increase the dissolved oxygen in the water being discharged from the water
passageway. Also an oxygen containing gas supply passes through the inner wall
of the draft tube at one or more chosen locations without requiring multiple gas
supply pipes passing through multiple locations spaced around the draft tube wall.
This simplifies or eliminates reconstruction of the concrete foundation about the
draft tube during refurberation of a turbine installation to accommodate gas supply lines.
In a typical hydraulic turbine installation, the concrete foundation is typically
provided with a person access passageway that leads to the draft tube wall and
a man hole door cover across an opening in the draft tube wall that permits access
to a person into the draft tube to effect any inspection or repair without having
to remove the turbine runner. It is envisaged within the preferred aspect of the
present invention that the oxygen containing supply extends through the person
access passageway and through the inside wall of the draft tube adjacent the man
hole door and into the gas distribution manifold. This provides the advantage that
the concrete foundation of the turbine installation does not have to be altered
for the insertion of an oxygen containing gas supply. Further, the oxygen containing
gas supply passes through the access passageway and is readily available for inspection.
It should be understood that in such instances, the gas distribution manifold does
not necessarily extend completely around the inside wall of the draft tube and
may stop at a portion of the draft tube inner wall adjacent the man hole door.
In one aspect of the present invention, the gas distribution manifold is provided
with gas outlet ports passing through a shroud covering each of the gas outlet
ports and providing an interior arrangement responsive to the flow of water along
the water passageway. It should be understood that these shrouds may extend further
into the water passageway than the inside wall of the gas distribution manifold.
The use of the shrouds creates a negative pressure adjacent the gas outlet ports
which draws gas through the gas outlet ports from the gas distribution manifold.
The number and shape of shrouds may vary to maximize their effect on drawing gas
from the manifold into the draft tube. Alternatively, one continuous shroud may
be attached to the manifold and extend around, or substantially around, the inside
of the draft tube wall.
In an alternative aspect of the present invention, the gas distribution manifold
may include a downstream inclined wall angled and extending from the inside wall
of the gas distribution manifold to the inside wall of the draft tube. A plurality
of gas outlet ports are located in the downstream inclined wall and as a result
provide a venturi arrangement responsive to the flow of water along the water passageway,
over the inside wall of the gas distribution manifold and the inside wall of the
draft tube.
The outlet ports of the gas distribution manifold may vary in size, number and
position around the gas distribution manifold so as to control the amount of oxygen
containing gas introduced into the water. It should be understood that the introduction
of oxygen containing gas to the gas distribution manifold at one or more locations
may result in a more concentrated introduction of the oxygen containing gas at
that location. Accordingly, the size, number and positioning around the gas distribution
manifold of the outlet ports may be varied in order to control the amount of oxygen
containing gas introduced into the water so as to provide for a more even distribution
of the oxygen containing gas into the water passageway. It is envisaged for example
that the outlet ports adjacent the oxygen containing gas supply line may be of
different number and/or size than the outlet ports displaced around the gas distribution
manifold and located further away from the oxygen containing gas supply line. It
is also contemplated that the gas distribution manifold may be provided with baffles
for regulating or directing the flow of oxygen containing gas thereabout and out
of the outlet ports.
The oxygen containing gas may be ambient air or alternatively the gas may be pressurised.
In accordance with an aspect of the present invention, there is provided a hydraulic
turbine adapted to introduce oxygen into water flowing through a water passageway
of the turbine. The turbine comprises a rotatably mounted runner and a draft tube
extending downstream of the runner. The draft tube has a first inside wall. The
turbine comprises a gas distribution manifold mounted to, and extending at least
substantially around, the first inside wall of the draft tube. The gas distribution
manifold has a plurality of gas outlet ports distributed around the gas distribution
manifold. The turbine comprises an oxygen containing gas supply passing through
the first inside wall of the draft tube and being connected to the gas distribution
manifold for supplying an oxygen containing gas to the gas distribution manifold
whereby the oxygen containing gas flows around the gas distribution manifold within
the draft tube and is discharged from the plurality of gas outlet ports of the
gas distribution manifold into the water passageway was to increase dissolved oxygen
in the water discharged from the water passageway.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the nature and objects of the present invention
reference may be had to the accompanying diagrammatic drawings in which:
FIG. 1 is an elevational view, partially in cross-section, of a Francis turbine
showing a gas distribution manifold mounted to the draft tube inside wall;
FIGS. 2A and 2B are partial sectional views showing a turbine runner and the
location of the gas distribution manifold;
FIG. 3 is a bottom view of the draft tube and distribution manifold of FIG.
1 taken along the line 3—3 shown in FIG. 1;
FIG. 4 is a view similar to FIG. 3 except that different gas outlet ports are
illustrated for the gas distribution manifold;
FIG. 5 is a view similar to FIGS. 2A and 2B illustrating the invention in use
with a fish friendly turbine runner.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to a hydraulic turbine and, in particular, to a
draft tube of a turbine adapted to increase the dissolved oxygen content of water
discharged from the turbine.
Referring to FIGS. 1 to 3, a portion of one embodiment of a turbine installation
10 is illustrated for use in the generation of hydroelectricity. The installation
10 has a water passageway
12. Water flows from an inlet
14
of passageway
12 to an outlet
16 located at a lower elevation. The
water passageway
12 passes through a Francis turbine
18 having a
runner
20 and a draft tube
22. The runner
20 is secured by
bolts
24 to a shaft
26 transmitting energy to a generator (not shown).
The turbine
18 is mounted in a stationary casing
28 having a head
cover
30 and a bottom discharge ring
32. The head cover
30,
discharge ring
32 and draft tube
22 are embedded in concrete foundation
34.
Runner
20 is rotabily mounted in casing
28 and has a crown
36
and a plurality of circumferentially spaced runner blades
38 extending therefrom
to an enclosing band
40.
It should be understood that installation
10 includes other components
such as, for example, stay vanes and wicket gates which are not shown.
The enclosing band
40 has a first diameter. The draft tube
22 has
a first inside wall
44 that has a second diameter. The second diameter is
measured adjacent the band
40 and is shown to be greater than the first
diameter of the band
40 in FIGS. 1 and 2A. The first inside wall
44
of the draft tube
22 is recessed outwardly as shown by a step
48
from the band
40. The draft tube
22 is also shown to diverge outwardly
as the draft tube
22 extends in the downstream direction. In FIG. 2B, the
first inside wall
44 of the draft tube
22 is substantially a continuum
surface from band
40 in the water passageway
22.
A gas distribution manifold
50 is mounted to and extends at least substantially
around a portion
45 of the first inside wall
44 of the draft tube
22. The manifold
50 is mounted to inside wall
44 by welding
of the manifold to the wall
44 whereby inside wall portion
45 forms
or defines one of the closing walls of the manifold
50. The gas distribution
manifold
50 has a second inside wall
52. This second inside wall
52 of the manifold
50 provides a continuum in the water passageway
12 from the enclosing band
40 of the turbine runner
20. This
continuum in the water flow passageway
12 does not introduce any encumbrances
that significantly affect or alter the water flow through the turbine runner
20
and the draft tube
22.
As shown in FIG. 2A, the band
40 has an outturned lip
41 that overlies
upper portion
43 of first inside wall
44 of draft tube
22
to allow for the runner to be temporarily supported on the top of the draft tube
during installation phase.
In FIGS. 1 to 3, the gas distribution manifold
50 is shown to comprise
outlet ports
56. The outlet ports
56 are spaced about the circumference
of the gas distribution manifold
50 and each have a shroud covering
60.
Shroud coverings
60 extend slightly into the water passageway
12.
The shroud coverings
60 cover the outlet ports
56 and provide a venturi
arrangement responsive to the flow of water along the water passageway
12.
This induces gas to flow out from the outlet ports
56.
A man hole door
64 is located in the first inside wall
44 of the
draft tube
22. The man hole door
64 provides access into the interior
of the draft tube
22 without having to remove the turbine runner
20.
The man hole door
64 is located at the end of a person access passageway
66 formed in the concrete foundation
34. The man hole door
64
is positioned in such a manner that the gas distribution manifold
50 does
not extend completely around the inside wall portion
45 of the draft tube
22. Further, the gas distribution manifold
50 may be provided with
baffles
68 which are shown in dotted lines in FIG. 1. The purpose of the
baffles
68 is to regulate the flow of gas within the gas distribution manifold
50. The manifold
50 in this preferred aspect comprises three walls
and is shown welded to the draft tube
22 with wall portion
44 closing
the manifold
50 to define an enclosed gas passageway. Alternatively, the
gas distribution manifold
50 could have an enclosed chamber in cross-section
that is mounted to inside wall
44 of draft tube
22.
The installation
10 further includes an oxygen containing gas supply
70
(see FIG. 3) in the form of two pipes
72 that pass along the person access
passageway
66, through the first inside wall
44 of the draft tube
22 and into the gas distribution manifold
50. In the embodiment shown
there are two gas supply entrances to the manifold
50. It should be understood
that more than two pipes
72 or only one pipe
72 may be utilized.
The oxygen containing gas supply
70 provides oxygen in the gas either in
the form of ambient air under no pressure, a pressurized gas, or a pressurized
ambient air. The gas flows either under pressure or due to the venturi effect along
the pipes
72, into the gas distribution manifold
50 and out the plurality
of outlet ports
56 into the water passing through the passageway
12
in the draft tube
22. This introduction of the oxygen containing gas into
the water passageway
12 of the turbine
18 increases the dissolved
oxygen in the water discharged from the water passageway
12.
Referring to FIG. 4, outlet ports
58 are shown located in a downstream
positioned inclined wall
62. In this embodiment the outlet ports
58
replace outlet ports
56. The Inclined wall
62 is angled from the
second inside wall
52 to the first inside wall
44 of the draft tube
22. This inclination provides a venturi arrangement for the outlet ports
58 that is responsive to the flow of water or water along the water passageway
over the first and second inside walls
44 and
52, respectively.
The outlet ports
56 or
58 may be uniformly spaced around the manifold
50 or, alternatively, may increase in number of outlet ports grouped together
in groups spaced evenly about the inclined wall
62. Hence, the size and
grouping of the outlet ports
56 and
58 may be chosen to control the
oxygen introduction into the water passageway
22.
Referring to FIG. 5, there is shown a turbine installation
10 having
a fish friendly turbine
100. As shown, the gas distribution manifold
50
is mounted to the inside wall
44 of draft tube
22 in the same manner
as that shown and described for FIGS. 1 to 3.
It should be understood that the shape of the manifold
50 may be different
than that shown in the illustrated embodiments. It is within the scope of the present
invention to alter the shape of the manifold
50 so long as the manifold
remains mounted to the inside wall of the draft tube
22.
While the invention has been described in connection with what is presently
considered to be the most practical and preferred embodiments, it is to be understood
that the invention is not to be limited to the disclosed embodiments, but on the
contrary, is intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
*
