FIELD OF THE INVENTION
The invention relates to high pressure Oil Header for blade turning mechanism of
Kaplan type Hydro Turbines. More particularly the invention relates to an
improved high pressure Oil Header with submerged leakage oil discharge.
BACKGROUND OF THE INVENTION
Oil Header is required in Kaplan Turbines for Oil pressure supply to the Runner
Servomotor (2) through concentric steel tubes (9) for oil passage. The main
function of an oil header (10) is to supply high pressure oil to said tubes (9)
rotating along with the runner (1) while minimizing leakage of oil which is
essential for effective functioning of said blade turning mechanism. Figure 1
illustrates a known arrangement of a blade turning mechanism of Kaplan
Turbines. The leakage of very high pressurized hot oil in the form of jets from
the clearances between a plurality of stationary body bushes and the rotating oil
tubes (9) might catch fire and hence it is necessary from safety aspects that the
leaking hot oil jets do not immediately come in contact with atmospheric air.

Earlier the oil pressure system used in old Kaplan Turbines was of quite low
pressure in the range of 40 to 60 kg/cm2. In such cases, asbestos rope gland
sealing (11) were used to minimize the leakage of oil from the oil header (10).
Figure 2 illustrates prior mechanism of oil header for such low oil pressure
systems. In these cases, the fibres of asbestos ropes (11) frequently get
detached in the relative zones of the interference between the bushes and the
rotating oil tubes (9) which further goes into a governor oil system necessitating
the use of a filter in the return oil circuit. Also the wear rate of these asbestos
ropes (11) is quite high which leads to shut down of machines every two months
of operation.
In order to reduce the servomotor sizes in the turbines, the prior art
subsequently had adopted high pressure oil systems in the range of 40 to 60
kg/cm2. The major challenge in operating with high pressure oil systems is the
safe and efficient functioning of the oil header (10) of Kaplan Turbines.
Presently, the oil pressure systems operate at a pressure range of 100 to 160
kg/cm2. In such cases, only a minimum leakage of oil may be allowed to ensure
effective functioning of blade turning mechanism (3). Also for safe working, an
arrangement is required to prevent leakage of hot oil in the form of fine jets and
mist to atmosphere to avoid catching fire inside the Oil Header (10).
As described herein above, with the advancements in very high pressure, oil
storage devices for example, nitrogen filled piston accumulators, adoption of
high pressure operating systems for turbine controls in the range of 100 to 160
bar is gaining popularity on account of the advantages of compactness and
economy.

Use of high oil pressure for turbine controls does not pose any such problem for
Pelton and Francis type hydro turbines; however it poses a problem in Kaplan
turbines on account of heavy leakages at the oil header supplying oil under
pressure to a runner servomotor (2) through the rotating oil tubes. Also the
leaking hot oil jets from the sealing bushes coming in contact with atmospheric
air carry the risk of catching fire.
CN 201220124863 discloses an oil-supply head sealing device for an axial flow
Kaplan turbine generator set. The oil-supply head sealing device comprises an
oil-supply head body, sealing covers and sealing rings, wherein operation oil tube
assembly holes are formed at the upper end and the lower end of the oil supply
head body; an oil cavity is formed in the oil-supply head body; the sealing covers
are fixed at the upper end and the lower end of the oil-supply head body; the
sealing rings are positioned in the assembly holes and comprise sealing limiting
sleeves; the sealing limiting sleeves are fixed on the sealing covers; the copper
sleeves are movably positioned in the sealing limiting sleeves; clearances are
reserved between the outlet walls of the copper sleeves and the inner walls of
the sealing limiting sleeve; limiting bosses positioned in the sealing limiting
sleeves are formed on the sealing covers; limiting slots of the sealing limiting
sleeves; limiting bosses positioned in the sealing limiting sleeves are formed on
the sealing covers; limiting slots corresponding to the limiting bosses are formed
on the copper sleeves; and the outer walls of the sealing limiting sleeves are
tightly attached to the inner walls of the assembly holes. The oil-supply head

sealing device has the advantages of compact structure and convenience in
machining and can prevent an oil-supply head from leaking oil; the use reliability
is improved; on the premise of guaranteeing the displacement of the copper
sleeves, the weights of the copper sleeves are reduced; the cost is reduced; the
friction is reduced; and a phenomenon that operation oil tubes are locked is
avoided.
CN 200810151364 teaches an oil-supply head of a Kaplan type turbine, which
comprises an operating oil pipe assembly, an oil-supply head body, a front oil
tank and a restoring mechanism; the oil-supply head is characterized in that the
operating oil pipe assembly comprising an inner pipe, a middle pipe and an outer
pipe is connected with the oil supply head body which is produced by a seamless
steel pipe into a whole structure, the outer wall of the operating oil pipe
assembly is sheathed with a sealing pad and a revolving ring, an oil-supply head
seat is connected with the oil-supply head body, one end of the oil-supply head
body is connected with the front oil-tank, the end part of the inner pipe of the
operating oil pipe assembly is connected with a swing link type restoring
mechanism; all pipe bodies of the operating oil pipe assembly are connected by
thread heads, the joint is provided with limited blocks, the outer walls of the
inner pipe and the middle pipe of the operating oil pipe assembly are fixedly
provided with guide blocks and limited blocks and the oil-supply head seat is a
steel plate welded structure. The oil-supply head has the advantages that the
outer pipe of the operating oil pipe assembly does not need the supplement of a
front-end shaft a generator, has more simplified structure, is convenient to install
and can avoid oil leakage; the restoring mechanism can accurately detect the
middle position of the stroke of a vane in virtue of the movement of a fork joint
and a swing link, thus leading to more accurate feed back and higher sensitivity.

CN 200820142645 discloses an improved structure of an oil supply head of an
axial-flow adjustable-blade water turbine. The improved structure comprises a
base fixedly installed on a collector ring cover, an oil dish positioned in the base
and fixedly connected with a front end shaft of a motor, an oil supply head body
fixedly installed on the base, and a floating tile installed on a tile seat of the oil
supply head body. The improved structure is characterized in that regulating
clearances are formed on the floating tile, and the end surface and the side
surface of the tile seat of the oil supply head body; and both the oil supply head
body and the oil dish adopt plate welding structures. The improved structure has
the advantages that the floating tile can achieve automatic position adjustment,
thereby avoiding problems of tile lapping, slip, oil leakage and the like during
operation of the oil supply head, which are caused by processing and installation
errors of operation oil pipes, so that the operation stability of the oil supply head
is ensured; besides, both the oil supply head body and the oil dish adopt the
plate welding structure, so that not only the quality of the oil supply head is
ensured, but also manufacture costs of the oil supply head is reduced; and
furthermore, the processing cycle is shortened.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved high pressure
Oil Header with submerged leakage oil discharge for blade turning mechanism of
Kaplan turbines.

Another object of the invention is to propose an improved high pressure Oil
Header with submerged leakage oil discharge for blade turning mechanism of
Kaplan turbines which minimizes the leakage of oil at high pressures.
A further object of the invention is to propose an improved high pressure Oil
Header with submerged leakage oil discharge for blade turning mechanism of
Kaplan turbines which prevents possibility of fire hazards inside the oil header.
SUMMARY OF THE INVENTION
Accordingly, there is provided improved high pressure Oil Header with
submerged leakage oil discharge for blade turning mechanism of Kaplan
turbines. The improved oil header addresses both the prior art problems of
heavy oil leakage and fire hazard. Oil leakage is minimized by providing a
plurality of throttle grooves and arranging an oil bleed-off from an intermediate
relief groove. The risk of fire hazard is eliminated primarily by locating oil
chambers at the ends of the top and bottom oil bushes so that the leaking oil
does not come in contact with air but gets submerged in oil. Additionally at end
of top and bottom bushes, an end relief groove has been provided with at least
six divergent angular exit grooves. These angular exit grooves are divergent
radially and tangentially so that escaping oil is highly diffused and not in the form
of jets. Also, the angular grooves being in a

direction opposite to that of direction of rotation resulting a reverse pumping
action, which further minimizes the leakage.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Overall Arrangement of a known Kaplan Turbine
Figure 2 : Prior Art Arrangement of oil header
Figure 3 : High Pressure oil header with submerged leakage oil discharge
according to the invention.
Figure 4 : Details of lower bush and lower chamber arrangement of the high
pressure oil header of figure 3.
Figure 5 : Details of lower bush exit grooves of the high pressure oil header
of Figure 3.
Figure 6 : Details of top bush and top chamber arrangement of the high pressure
oil header of Figure 3.
Figure 7 : Details of angular exit grooves of the top bush of the high pressure
oil header of Figure 3.

DETAILED DESCRIPTION OF THE INVENTION
In Kaplan Turbines of Hydro-Electric projects, an oil pressure system is required
for Runner servomotor (2) for Blades turning operations. The oil chambers of
these servomotors are installed inside a Runner Hub and Cone, Comprising of
piping system of concentric tubes for these chambers is installed in the central
bores of turbine and generator shafts. These tubes are connected to the oil servo
chambers inside the Runner Hub and hence these oil tubes are rotating along
with the Runner.
According to the invention, the improved oil header (10) is an arrangement of a
fabricated steel structure mounted at the top of the generator for oil
connections. The Oil header (10) ensures proper communication of oil through
the rotating tubes (9) right from the generator top, up to the runner servo
chamber inside the runner hub. It is provided with bearing and sealing
arrangement for smooth running operation with ability to absorb wobbling of the
generator top shaft on which the oil header (10) tubes are mounted. The main
challenge of the system is to minimize the leakage corresponding to the
wobbling effect of the rotating oil tubes.
For the inventive high pressure oil systems, a plurality of throttle grooves are
provided in the bearing (12,13, 14) to minimize the oil leakage. At a location of
about 40% to 50% of throttle grooves, a relief chamber (15) is provided from
which oil is bleed off (16) to relieve the pressure (refer Figure 3). This would
thus reduce the oil pressure for the next stage of the throttle grooves and thus
minimize the oil leakage.

Another major concern in high pressure oil header is that the oil which escapes
through the fine bearing clearances gets heated up. Hence the most important
safety aspect of the improved high pressure oil header is that the hot oil leaking
in the form of fine jets might catch fire while leaking into the atmosphere. To
take care of this, oil chambers (18 and 21) have been introduced at both the
ends of top and bottom bushes (12, 14) so that the hot pressurized leakage oil
jets are not exposed to the atmosphere but are submerged in oil.
The hot oil leakage from the bushes (12, 14) might come out to the atmosphere
in the form of vertical jets. To prevent such occurrence, an end relief groove (19)
is made at the end of second stage of throttle grooves and divergent angular exit
grooves (20) are made in a direction opposite to the direction of rotation of the
system. Refer detail of grooves in figures 5 and 7. Such divergent angular exit
grooves (20) have the following functions:
a. Six to eight of such grooves are provided having a combined area, higher
than the clearance area between the rotating oil tube and the bush. Thus
this enlarged area of the exit grooves (20) ensures that the velocity of
leaking oil drops down drastically and leaking oil does not spurt out in the
form of jets or mist.
b. The grooves being at an angle, the leakage jets from the end of the bush
does not escape vertically through the clearance / gap. The jets if any
comes out of an angle, somewhat tangentially creating a swirl action.

c. The angular grooves (20) are divergent in the radial direction also, so that
the leaking jets which are highly diffused are also at an angle to the
vertical escape through a vertical gap.
d. If the angular grooves are in the same direction as that of rotation, a
sucking action will generate and leakage will increase. Hence by making
the angular grooves in the opposite angle from the direction of rotation,
the rotation of the tubes will oppose the leakage of oil and hence the
discharge of leakage oil would reduce.
Thus, the improved high pressure oil header becomes safe and effective on
account of the following features:
i) Location of the Oil Chambers (18 and 21) allowing a submerged oil
leakage;
ii) a plurality of throttle grooves with intermediate bleed off (16) to
minimize leakage; and
iii) a plurality of divergent Angular exit grooves (20) at the end of the
bushes in a direction opposite to the direction of rotation of the tubes
minimizes leakage and prevent leakage oil jets from coming out
vertically.

List of features of the invention
1. Runner
2. Runner servomotor
3. Blade Turning mechanism
4. Blade
5. Turbine Shaft
6. Generator Shaft
7. Generator Rotor
8. Generator Brush Gear Housing
9. Oil Tubes
10. Oil Header
11. Asbestos gland packing
12. Bottom guide bush / bearing
13. Middle guide bush / bearing
14. Top Guide bush / bearing
15. Relief Groove
16. Bleed-off tapping
17. Throttle Grooves
18. Lower chamber
19. End Relief groove
20. Divergent angular exit grooves
21. Upper Chamber

WE CLAIM:
1. An improved high pressure Oil Header with submerged leakage oil discharge for
blade turning mechanism of Kaplan turbines, the oil header (10) mounted on the
top shaft of the generator to supply high pressure oil to a blade turning
mechanism through a plurality of concentric metallic tubes (9) rotating in
registration with the rotation of the turbine blades, the rotating tubes acting as a
continuous oil passage from the generator up to a servo chamber disposed inside
the (12, 13, 14) with sealing means provided to allow smooth operation of the
turbine and minimize oil leakage, the improvement is characterized in that:
a first plurality of throttle grooves to minimize oil leakage constructed on
the bearing bushes (12, 13, 14) extending till a location where a relief
chamber (15) is provided for oil bleed off tapping (16) to relieve oil
pressure;
a second plurality of throttle groove provided after the bleed off (16) to
ensure both reduction in oil pressure and minimization of oil leakage;
one each oil chamber (18, 21) provided respectively at top and bottom
bush ends (12, 14) to allow the pressurized leakage oil jets to be
submerged instead of directly discharged to the atmospheric air; and

multiple divergent and angular exit grooves (20) in a direction opposite to
the rotational direction of the turbine blades are configured on an end
relief groove (19) formed beyond the second plurality of throttle grooves
to ensure exit of leaking oil at a low velocity.

ABSTRACT

The invention relates to an improved high pressure Oil Header with submerged
leakage oil discharge for blade turning mechanism of Kaplan turbines, the oil
header (10) mounted on the top shaft of the generator to supply high pressure
oil to a runner servomotor through a plurality of concentric metallic tubes (9)
rotating in registration with the rotation of the turbine blades, the rotating tubes
acting as a continuous oil passage from the generator up to a servo chamber
disposed inside the (12, 13, 14) with sealing means provided to allow efficient
operation of blade movement and minimize oil leakage, the improvement is
characterized in that a first plurality of throttle grooves to minimize oil leakage
constructed on the bearing bushes (12, 13, 14) extending till a location where a
relief chamber (15) is provided for oil bleed off tapping (16) to relieve oil
pressure; a second plurality of throttle groove provided after the bleed off (16)
to ensure both reduction in oil pressure and minimization of oil leakage one each
oil chamber (18, 21) provided respectively at top and bottom bush ends (12, 14)
to allow the pressurized leakage oil jets to be submerged instead of directly
discharged to the atmospheric air; multiple divergent and angular exit grooves
(20) in a direction opposite to the rotational direction of the turbine blades are
configured on an end relief groove (19) formed beyond the second plurality of
throttle grooves to ensure exit of leaking oil at a low velocity.