FIELD OF THE INVENTION
The present invention relates to a steam blowing device for IP control valve to prevent entry of leaked steam from blowing device of IP stop valve to IP Control valve in a stream turbine.
BACKGROUND OF THE INVENTION
Steam blowing of Reheat steam pipe lines of steam turbine is carried out in order to remove welding slag, grease, loose foreign materials, iron pieces, rust etc. from the system, generated during manufacturing, transportation and erection. Steam blowing operation of the pipe lines is of great importance to ensure satisfactory operation of steam turbines as impurities in the steam can deposit on the turbine blades, imbalance the rotor chain and damage the valve and turbine components.
During steam blowing operation, steam of high pressure (45-60 bar) and temperature (530°C-550°C) is blown in the pipelines. This steam is bypassed upstream of turbines using steam blowing devices to prevent ingress of impurity in turbines during steam blowing operation as per arrangement shown in figure-1. As per normal practice, at least one Steam blowing device is installed in IP stop valve. Steam enters into the IP stop valve from an inlet connection and blown out from an outlet connection (shown in figure-1).

During this operation, the on-going steam flow to the IP control valve is blocked by the steam blowing around the IP stop valve at its valve seat area. However, this process of blocking steam flow at IP stop valve, fails to completely ensure steam leakage to the IP Control valve.
To prevent any risk of ingress of impurities through leaked steam-flow to the IP control valve, in turn to the turbine due to the leakage in said steam blowing device of IP stop valve, a steam blowing device for IP control valve has been proposed to additionally seal the valve seat surface of the IP control valve. Before installing the steam blowing device within the IP control valve, internal components of the IP-Control valve, are taken out from the valve body.
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose a steam blowing device for IP control valve to prevent entry of leaked steam from blowing device of IP stop valve to IP Control valve in a stream turbine.
SUMMARY OF THE INVENTION
Accordingly, there is provided a steam blowing device for IP control valve to prevent entry of leaked steam from blowing device of IP stop valve to IP Control valve in a stream turbine. The device comprising a spindle, a first end

of which abuts with a central portion of a plug having a circular cross section, a second end of said spindle having an external thread for passing through a cover plate having matching internal thread; wherein a pipe is welded at a Central location on the inner surface of the plug (3) for aligning the spindle on the central axis such that when the spindle is tightened in the cover plate, it creates a push force on the inner surface of the plug, to allow abutting of inclined surface of the plug with the valve seat face of said IP control valve.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Cross-section view of IP stop cum control valve indicating major components of Steam blowing device for IP control valve;
Figure 2: Front view of the steam blowing device assembly indicating different components.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
As shown in figure 1, the inventive steam blowing device for IP control valve consists of a cone shaped Plug (3) which seats on a Diffuser (A) of the IP control valve. The Plug (3) is having very fine surface finish to make a steam tight surface contact with the Diffuser (A) of IP control valve. Plurality of special plates (6) having rectangular cross-section are welded on diffuser side surface of the Plug (3), 90 degree apart from each other which gets inserted

in the inner diameter of the diffuser so as to hold the Plug (3). A Spindle (2) pushes the Plug (3) towards the diffuser. Outer end of the Spindle (2) is having external thread which joins with a Cover plate (1) having matching internal threads. Tightening of the spindle (2) with the Cover plate (1) provides a push force to the plug (3). Inner end of the spindle (2) is aligned with the centre of Plug (3) through a pipe (5) which is welded on the plug (3). The cover plate (1) is mounted on the existing valve casing (D) of the IP Control valve by a plurality fasteners (7). As the complete valve casing is not covered by the Cover plate (1) and IP control valve seating surface area is blocked by the Plug (3), steam leaked from IP stop valve shall come out from the cover plate side, without entering into the IP control valve and in turn to the Steam turbine.

WE CLAIM:
1. A steam blowing device for IP control valve to prevent entry of
leaked steam from blowing device of IP stop valve to IP Control valve
in a stream turbine comprising:
a spindle (2), a first end of which abuts with the central portion of a plug (3) having circular cross section, a second end of said spindle (2) having an external thread (E) for passing through a cover plate (1) having matching internal thread;
wherein a pipe (5) is welded on the inner surface and centre of plug (3) for aligning the spindle (2) on the central axis such that when the spindle (2) is tightened in the cover plate (1) a push force is generated on the inner surface of the plug (3) thus abutting its inclined surface (F) with a Diffuser face (A) of the IP control valve.
2. The device as claimed in claim 1, wherein a plurality of plates (6) having rectangular cross-section are positioned on the outer surface of plug (3) at 90° apart and welded therein.
3. The device as claimed in claim 1, wherein when the push force applied on the plug (3) by the spindle (2), the inclined surface (F) of plug (3) abut with the surface of the diffuser (A) of the IP control valve.
4. The device as claimed in claim 1, wherein the cover plate (1) is mounted on the valve casing (D) by a plurality of fasteners (7).