REUSABLE PLATFORM FOR IN- SITU TURBINE ASSEMBLY
FIELD OF THE INVENTION
The present invention relates to the reusable platform for the assembly of high backpressure supercritical low pressure turbine components. More particularly the present invention provides a reusable platform to be used between inner casing and outer walls of the low pressure turbine to ensure the accessibility to the turbine components to complete the turbine assembly.
The reusable platform for the assembly of high back pressure supercritical low pressure turbine with air cooled condensers hereinafter referred as ‘platform’.
Turbines used in coal or nuclear fuel based thermal power plants shall hereinafter referred as ‘turbine’.
BACKGROUND OF THE INVENTION
A thermal power station is a power plant in which heat energy is converted to electric power. The working fluid is recycled by condensing it to original state i.e. at low pressure & low temperature, and then fed back to turbine through boiler to produce electricity continuously. The way of heat generation from fuel decides the name of the power plant i.e. if nuclear energy is used to generate heat and that heat gets transformed into electricity then it is called a nuclear power plant, if coal energy is used to generate heat and that heat gets transformed into electricity then it is called a conventional thermal power plant while working fluid in both of the power plants is same that is water.
In a thermal power plant a steam turbine rotor is rotated with help of high pressure and high temperature steam and this rotational kinetic energy of rotor is

transferred to the generator through coupling, where it gets converted in to electricity (Refer figure-3).
Turbine rotor gets rotated by high pressure high temperature steam, converting the heat energy of steam into kinetic energy of rotor; this in turn will result in a low pressure and low temperature steam in the successive stages of turbine. As soon as the pressure of steam get reduced the specific volume of steam increases, and more space is required to pass that much of steam through the turbine. This is why the size of Intermediate turbine is greater than high pressure turbine and low pressure turbine is larger than intermediate pressure turbine. Because of high specific volume the low pressure turbine becomes as big as a rectangular hall
(refer figure-1 & 2).
Because of space limitation as well as ease of circulation the condenser is located under the turbine due to this the turbine floor lies at a height of 17-18 meter above the ground; hence the open low pressure turbine enclosed by its two side walls and two ends walls looks like a rectangular well. The inner casing of low pressure turbine is to be fitted in this open rectangular space, for which a customized platform is required which is to be successfully installed at the walls to execute the assembly work of inner casing and turbine components such as shaft sealing, shaft seal compensators, guide blade carriers, fasteners and other parts and finally to be removed safely from the position to fulfill the functional requirement of the turbine.
After completion of assembly the device needs to be removed safely from its position and may be used in other successive units for assembly. At the time of

overhaul the device will be required again to reach up to the preinstalled components /subassemblies. To make the device reusable it’s mounting is kept on threaded fasteners which can be loosened easily without using flame/torch to cut the parts, because use of torch generates stress and spatters may damage the device, condenser tubes and turbine components.
Earlier temporary supports, wooden batten, wooden shattering, open steel gratings etc. are used for this purpose. Open steel gratings can be used only when their ends are simply supported, it is generally avoided in case of overhung or cantilever supports because cantilever portion bends when load is applied. In the subcritical machines the inner casing rests on girders which provides the simple support to use the open steel gratings but in super critical sets the LP inner casing is supported on pedestals only and creates a big void which needs to be covered with such platform before starting the assembly work. The invented device replaces the use of old technique of using simply supported open steel gratings by opaque steel solid gratings on overhung and cantilever support for the platform.
As far as high back pressure turbine is concerned it has a narrow construction due to which it is not possible to put the simply supported beams to make the platform by wooden batten or open steel gratings. To deal with such situations overhung and cantilever beams are used with solid opaque steel gratings. Open gratings can be used only when their ends are simply supported, it is generally avoided in case of overhung or cantilever supports because cantilever portion bends when load is applied. Which is not safe and work friendly as utensils tools and other small items fall into it also person standing on open gratings frightens due to visibility of depth through it. In the design code safety comes first which has to be incorporated to avoid any fatal during erection.

In view of above there was a need of a reusable platform for in-situ turbine assembly which is easy to install, safe, reliable, and easy to dismantle without damaging any component.
OBJECT OF THE INVENTION
The object of present invention is to provide a reusable platform which provides the accessibility to execute the assembly of LP turbine components such as shaft sealing, shaft seal compensators, LP inner casing, guide blade carriers, fasteners and other components as well as the same must be removable safely and easily from its position after completion of assembly so that it could not create any hindrance in the performance of intended function of turbine.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure-1 outer casing of a low pressure turbine, isometric view showing inside space.
Figure -2 plan view of L.P turbine with rotor.
Figure-3 is a diagrammatic representation of power production in thermal power plants by steam turbine.
Figure-4 is a 3-dimensional isometric view of the invented device representing constructional details from bottom.
Figure-5 is a 3-dimensional isometric view of the invented device representing constructional details from top.

SUMMARY OF THE INVENTION
The arrangement basically consists of a number of support elements to hold the platform successfully at a specified height from the ground. Few of these support elements are permanently welded with casing for lifetime use of it, while others are threaded fasteners that can be removed by loosening it with help of a simple spanner after completing the assembly work.
DETAIL DESCRIPTION OF WHOLE ARRANGEMENT OF THE ASSEMBLY PLATFORM.
All the major components have been marked in the Figure-4. Details of major components of proposed device, their functions and assembly procedure is described below for better understanding of invented device.
1. Assembly of Supports (item no. 4, 5, 12, 14, 17, 19 & 20): First of all bracket support (item no. 4) & pipe support (item no.5) is to be welded with middle plate of casing frame section, plate (item no.12), Tee plate (item no.14) & plate (item no.17) are to be welded with casing side wall and plates (item no. 19 & 20) are to be welded with casing end wall at a specified location as a permanent support of invented device.
2. Assembly of Longitudinal Beam (item no. 1): Longitudinal beam (item no 1) is now simply supported on bracket support (item no. 4) &plate (item no. 20) followed by bolting successfully with the help of screw M20*50 (item no. 26)& Serrated washer (item no.-28) with the plate (item no. 20) which is already welded with casing end wall.

3. Assembly of Beam (Item no. 3): One end of the Beam (item no 3) is now simply supported on longitudinal beam (item no. 1) and other end is successfully bolted with the help of fasteners screw M20*50 (item no. 26) & Serrated washer A21.4x30.7x3.0 (item no.-28) with the Tee-plate (item no. 14) which is already welded with casing side wall, followed by welding of beam (item no.3) with longitudinal beam (item no.1) keeping perpendicular to each other as shown in figure- 4.
4. Assembly of L - shaped Beam (Item no. 2) & Strap (items no. 18):
Firstly both the L-shaped beams are to be coupled by double strap joint as shown in figure-4 with the help of strap (item no. 18), bolt M20*50 (item no. 26) & Nut M20x1.5 (item no. 27) & Serrated washer A21.4x30.7x3.0 (item no.28) then it is to be kept simply on pipe support (item no. 5) and longitudinal beam (item no. 1) for welding it with longitudinal beam (item no-1).
5. Assembly of Angle supports (item no.15 & 16) and Plate Item o.13:
Angle support is to be kept over the support plates (items no. 12, 14 & 17) in such a manner that the open end of angle is upward, then by putting the plate (item no. 13) at the position the locations of plate (items no.13) are marked on angle support by matching the threaded holes. Plates (item no.13) are to be welded with angle support by taking angle support out from the position. Now angle support with plates again placed at the position and fastened with support plates (item no.12, 14 & 17) with the help of screw M20*50 (item no. 26) & Serrated washer A 21.4x30.7x3.0 (item no.-28) as shown in figure-4.

6. Assembly of Grates & nuggets (Item no. 21, 22, 23, 24 & 25):
Nuggets are already welded with the supplied grates at their specified locations in each grate. After completion of angle support assembly grate (item no. 21) to be placed at the left most position, grate (item no. 23) to be placed at the right most position, grate (item no. 22) to be placed at the middle position and a number of prefabricated customized length general grate (item no.24) are to be placed at their corresponding positions as shown in figure-4. To avoid vertical lift of all the grates from their specified position, a number of plates (item no.34) of cross section 5x70 with desired length to be welded with angle support over the grates successfully.
7. Assembly of cantilever Beams (item no. 6 &7) & Plates (item no. 8): Plates (item no. 8) are welded with Cantilever beams (item no. 6 & 7) with weld seam of size 5mm all around the beams, while other stiffening items (not itemized here) of platform (item no. 9 & 10) are already welded with beams to complete the platforms (item no. 9 & 10).
8. Assembly of platforms (item no. 9 & 10) Platforms (item no. 9 & 10) are mounted on casing end walls opposite to each other with the help of screw fastener M20x80 (item no. 32) and serrated washer A21.4x39.0x3.2 (item no.33) through end wall with the threads of support plate (item no. 19) as shown in figure -4.

9. Assembly of platforms (item no. 11): Platform (item no.11) to be assembled between platform (item no. 6) and longitudinal beam (item no. 1) as well as platform (item no. 7) and longitudinal beam (item no. 1) on other side of turbine with the help of Bolt M12x100 (item no. 29), Nut M12 (item no. 31) and serrated washer A13x19.5x2.2 (item no. 30) through grates already spread on longitudinal beam. Now the working platform is ready for its intended function i.e. assembly of LP turbine can be done successfully just by standing on it.
10. Removal of platform: This platform can be easily removed by loosening the fasteners and also remounted quickly at another turbine because few of important assembly work is already completed and need not to dismantle while removing. Permanent supports item no. 4, 5, 12, 14, 17, 19 & 20 are left in their position as it is, these items will be required new to mount the removed platform on other turbine.

We Claim
1. A reusable platform for in- situ assembly of steam turbine components comprising:¬- bracket (4) and pipe support (5) welded with the middle plate of casing frame section (fig.1), plate (12), Tea plate (14), plate (17) welded with the inner side of casing side wall (fig.1) and plates (19,20) with inner side of casing end wall at a specified location as permanent support for the platform where the location of the components are shown in the platform in fig (4);
- a plurality of longitudinal beams (1) coupled by double strap joint (18) with the help of bolt (26) and nut (27) and washer (28) are simply supported at location bracket support (4) at the middle and over plate (20) already welded with the casing end all at specified location;
- a pair of L-shaped beam (2) coupled together by double strap joint (18), bolts (26) and nuts (27), the said beam (2) being simply supported at location pipe support (5) and over the longitudinal beam (1) and welded therein;
- a pair of beams (3) placed across the platform with one end resting over the longitudinal beam (1) followed by welding whereas the other end is bolted with the help of bolts (26) with the Tea-plate (14) already welded in the casing side wall;

- angle supports (15, 16) disposed over the support plate (12, 14, 17) in such a manner that the open end of angle support facing upward and then plates (13) are welded with angle support (15,16);
- grates (21, 72, 23, 24) with nuggets (25) welded therein and placed at specified location ;
- cantilever beams (6, 7) welded with plates (8) form part of the platforms (9,10) mounted on casing end walls opposite to each other with the help of bolts (32), washer (33) with the threads of support plate (19) as shown in fig.4 wherein the platform (11) disposed between the cantilever beam (6) and longitudinal beam (1) in one side and beam (7) and longitudinal beam (1) on other side.
2. The platform as claimed in claim 1, wherein the parts are disassembled after completion of the turbine assembly except the items (4,5,12,14,17,19 & 20) which are left in their position as it is in (fig.1).