FIELD OF THE INVENTION
The invention relates to a device and method for aligning the inner and outer
casing for High pressure (HP) / Intermediate pressure (IP) steam turbine.
More particularly it relates to a device and method for aligning inner and
outer casing of HP/IP module steam turbine where there exists a close
dimensional clearances between the blades and outer casing.
BACKGROUND OF THE INVENTION
Large steam turbines are made up of High pressure (HP), intermediate
pressure (IP) and low pressure stages. These stages consists of an inner casing
and an outer casing. During assembly of HP/IP stages, it requires to adjust the
HP/IP inner casing in line with the outer casing and with respect to rotor. This
is a fine adjustment and very critical to adjust because of its close (0.8-1.1
mm) radial clearances in blading area. To get the above clearances it is
necessary to hold inner casing rigidly with respect to outer casing. To achieve
this, the designers provide a pin called eccentric bolt, which holds the
innercasing rigidly with outercasing.
The present process of assembling the Inner casing (1/C) with outer casing
(O/C) involves
i) Lowering of outer casing bottom half on assembly bed.
ii) Centering outer casing bottom half with respect to bearings.
iii) Lowering of inner casing bottom half with bottom fitted keys into the
outer casing bottom half.
iv) Centering of inner casing with respect to outer casing bottom half.
v) For centering the inner casing bottom half, eccentric bolt has to be
placed in the outer casing whose top head will enter into the inner
casing fitted key's center hole.
vi) To properly aligning the innercasing with the outercasing, the eccentric
bolt has to be rotated till desired tolerances are achieved.
vii) The eccentric bolt will have slot at the bottom coller.
viii) To rotate the eccentric bolt, a rod has to be placed into the slot and it
has to be hammered to rotate it till required tolerances on alignment of
innercasing are achieved.
Drawbacks of the present system
- The process of hammering the rod placed inside the eccentric collar is an
unsafe practice.
- This process requires, more manpower for holding and hammering the rod.
- The eccentric bolt may fall down while rotating during assembly.
- There are chances of damging the eccentric bolt.
- It is a time taking and tedious process.
OBJECTS OF THE INVENTION:
It is therefore an object of the present invention to propose a device for
aligning the inner and outer casing for HP/IP module steam turbine which
eliminates the disadvantages of the prior art.
Another object of the invention is to propose a device for aligning the inner
and outer casing for HP/IP module steam turbine which saves a lot of time
while increasing the quality of work.
A further object of the invention is to propose a device for aligning the inner
and outer casing for HP/IP module steam turbine which eliminates the unsafe
working.
SUMMARY OF THE INVENTION
A device (1) for aligning the inner (9) and outer casings (8) for HP/IP module
steam turbine comprising:
a block body (2) supported between the eccentric bolt (7) and holding plate
(3) for avoiding the falling; the holding plate (3) suspended from the outer
casing characterized in that, the block body (2) having plurality of teeths (2c)
on diametrically opposite end on top face (2b) that exactly matches the
groove (7a) on bottom collar of the eccentric bolt (7) such that a forged
spanner (4) rotates the block body (2) which in turn gives radial movement of
the inner casing (9) via bolt head (7b) and fitted key (10) thus aligning the
inner casing (9) with respect to outer casing (8).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 - Prior art system of aligning the inner and outer casing
Fig. 2 - The block body having plurality of teeth on the upper face and lower
half with hexagonal surface for gripping by the forged spanner.
Fig. 3 - The invented device in the machine set up during alignment of inner
casing with respect to outer casing.
Fig. 4 - The holding plate (3)
DETAILED DESCRIPTION OF THE INVENTION
The invented device (1) is a kind of holding and adjusting mechanism which
helps to hold and rotate the eccentric bolt (7) of HP/IP turbine.
It consists of a hollow block body (2) which has a hexagonal surface at the
lower portion (2a) and plurality of teeths (2c) on the top surface (2b), a
holding plate (3) having 2 holes at the distal ends for holding by studs (5) and
nut (6), the holding plate (3) has a central hole for accommodating the
protruding portion (2a) of the block body (2). The holding plate (3) is
suspended from the outer casing
(8) by studs (5) and nuts (6) and hold the block body (2) between the bottom
collar face of eccentric bolt (7) and the neck of the block body (2).
The eccentric bolt (7) needs to rotate from outside bottom of outer casing (8)
to move the inner casing (9) in the required direction (left or right) through
the fitted key (10). Here the torque applied on the eccentric bolt (7) is
transmitted to the inner casing (9) via the fitted key (10) which hold the head
(7b) of eccentric bolt (7).
The developed device will play the role to hold the eccentric bolt (7) as well
as rotate the eccentric bolt (7) with great torque and easier way
The eccentric bolt is having a tapped hole and a slot (same as mentioned
above) at the bottom of its collar. The teeths of the block body sits into the
slot with minimum clearance and the holding plate (3) gives support to the
main fixture from falling down.
The holding plate (3) also has two holes, which helps to hold this fixture with
the outer casing (8) of the turbine through already drilled tapped holes which
are drilled for holding the flange. This flange is placed after alignment.
Now with the help of a forged spanner and a hammer the main fixture can be
easily rotated by a single man.
We claim
1) A device (1) for aligning the inner (9) and outer casings (8) for HP/IP
module steam turbine comprising:
a block body (2) supported between the eccentric bolt (7) and holding plate
(3) for avoiding the falling; the holding plate (3) suspended from the outer
casing characterized in that, the block body (2) having plurality of teeths (2c)
on diametrically opposite end on top face (2b) that exactly matches the
groove (7a) on bottom collar of the eccentric bolt (7) such that a forged
spanner (4) rotates the block body (2) which in turn gives radial movement of
the inner casing (9) via bolt head (7b) and fitted key (10) thus aligning the
inner casing (9) with respect to outer casing (8).
2) The device (1) as claimed in claim 1 where in the lower portion (2a) of the
block body (2) is hexagonal and the upper face (2b) has plurality of
diametrically opposite teeths (2c).
3) The device (1) as claimed in claim 1 where a close dimensional tolerance is
maintained between the teeths (2c) of block body (2) and the groove (7a) at
the bottom collar face of eccentric bolt (7).
4) The device as claimed in claim 1 where the holding plate (3) has plurality
of holes at the distal ends for holding the plate in suspended condition by
studs (5) and nuts (6) and a central hole for accommodating the potruding
portion of the block body (2).
5) A method for aligning the inner casing (9) of the steam turbine with outer
casing (8) by the device (1) as claimed in claim 1 comprising:
- lowering the inner casing (9) bottom half with bottom fitted keys (10) in to
the outer casing (8) bottom half.
- placing the eccentric bolt (7) in the outer casing (8) whose top head (7b) will
enter in the hole of fitted key (10) of inner casing (9).
- holding the block body (2) by the holding plate (3) with the help of studs
(5) and nuts (5) wherein the studs (5) are suspended from outer casing (8).
- positioning the block body (2) such that the twin teeths (2c) of the block
body (2) sits on the groove 7a of the eccentric bolt (7).
- Rotating the forged spanner (4) right or left by a hammer for aligning the
inner casing (9) with respect to outer casing (8).

ABSTRACT

The invention relates to a device and method for aligning the Inner casing
with respect to Outer casing for HP/IP module steam turbine where there
exists a close dimensional clearance between the blades and outer casing.
The device comprising a block body (2), supported between an eccentric
bolt (7) and holding plate (3), the holding plate (3) suspended from outer
casing (8), the block body (2) having plurality of teeths (2c) which fit
into grove (7a) of the eccentric bolt (7) such that a forged spanner (4)
rotates the block body (2) which in turn transmit the rotation to inner
casing (9) via eccentric bolt (7) and fitted key (10) thus aligning the inner
casing (9) with respect to outer casing (8).