FIELD OF THE INVENTION
The present invention relates to an improved steam conditioning valve operable at
super critical parameters of steam in a turbine-bypass system.
BACKGROUND OF THE INVENTION
HP by-pass valves are used for steam conditioning in the Turbine-bypass system in a
power plant. Steam at a high pressure and temperature entering in the inlet of the
valve is reduced to a low pressure and temperature to match the cold Reheat Line
parameters in the boiler.
Basically, the steam entering in the valve body is throttled to achieve higher pressure
drop. Simultaneously, spray water is injected into the throttled steam. The spray water
is atomized to achieve a thorough mixing of the water with the incoming steam to de-
superheat the steam.
The profile of the valve body and the internal components are designed in such a way
that vibration, noise level and water hammer effect are brought to a minimum level.
The valve including the upstream and down stream pipes are safeguarded against any
damage during the by-pass of steam.
According to the prior art, such valves are manufactured for sub-critical parameters of
steam. However, prior art do not report producing steam conditioning valves used for
super-critical parameters of steam. Manufacture of such valves require new materials,
improved welding technique and an innovative manufacturing process.

OBJECTS OF THE INVENTION
It is therefore an object of invention to propose an improved steam conditioning valve
operable at super critical parameters of steam in a turbine-bypass system, which has
the valve body, valve seat, inlet nozzle and outlet nozzles, each formed of a first
material suitable to withstand higher temperature and higher pressure.
Another object of the invention is to propose an improved steam conditioning valve
opening at super critical parameters of steam in a turbine-bypass system, in which the
valve body after welding with the nozzles can be machined to a smooth curved profile.
A still another object of the invention is to propose an improved steam conditioning
valve operable at super critical parameters of steam in a turbine-bypass system, in
which the shape of the valve body is optimized to minimize the operational thermal
stress.
A further object of this invention is to propose an improved steam conditioning valve
super critical parameters of steam in a turbine-bypass system, which has jet cage,
Penstock and Pressure Seal Plug formed of a second material operable under higher
temperature and higher pressure.
A still further object of this invention is to propose an improved steam conditioning
valve super critical parameters of steam in a turbine-bypass system, which has jet
cage, Penstock and Pressure Seal Plug formed of a second material operable under
higher temperature and higher pressure, in which the valve steam is made of a third
material.

SUMMARY OF THE INVENTION
According to the invention, the valve body is formed of F-91 material. Profile
machining of this valve body is carried out to maintain an uniform thickness is
maintained on the body.
Inlet Nozzle and outlet Nozzles are made of F91 forgings and are machined to suit the
bellies of the body. The Nozzles are weldably fitted to the valve body. The welding is
carried out under controlled conditions to avoid distortions during welding. Suitable
preheating, post heating and post weld heat treatment is maintained. The weld joint is
examined for Radiographic test and Ultrasonic test.
The Valve body is machined to a close tolerance where the other internals are
housed.
The seat rings are made of F-91 materials with stellite cladding and are machined and
drilled to a close tolerances.
The jet cage, Penstock, are made of F-91 material with hayness welding on Jetcage
and Hayness plus stellite cladding on Penstock. They are machined and drilled to a
closer tolerances.
The pressure Seal Plug is made of F-91 material machined to closer tolerances.
The valve stem is formed of X19CrMo material, and having grooves with aerodynamic
profiles to allow the steam flow to split into discrete paths.
The seat ring is positioned in the body and secured by means of a Welding Jig and
welding is carried out. By this method, the distortion during welding is controlled. The
co-axiality of the stem, the Seat ring, the penstock, and the Jet cage is perfectly
maintained without any distortion during this welding.

A lapping of the Valve seat is done. Assembly of all the components is done and
hydraulic testing is carried out for this valve.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure-1 Cross sectional view of the HP-Bypass valve according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Figure-1 illustrates the HP-BYPASS VALVE of the invention. The valve comprises:
-a valve body (1) having two hemisphere shaped bellies made of material SA 182 F91;
at least one inlet Nozzle (F-91) and a plurality of outlet Nozzles (F-91) welded to the
valve body (1);a spool piece (F22 material) welded with full penetration at an extreme
end of the outlet nozzle; the valve body (1) being stress relived after welding and then
machined to a final dimension.
-a Valve Seat (3) made of F-91 material with stellite cladding (S-CoCr20W15Ni), the
valve seat (3) weldably fixed to the valve body (1); and firmly secured and welded.
-a Stem (2) produced of material X19CrMoNbN11-1, and machined to a matching
profile of the valve body (1);
-a Jet cage (9) machined and drilled from F-91 material and provided with holes
including stellite cladding;

a Penstock (80) formed of F-91 material cladded with S-Co65Cr25W, and having a
plurality of holes;
-a Gland bush (43) made of Monel K500 material;
-a Gland Retainer (41) made of Sa 182 F6a cl.3 material;
-One each Pressure Seal Plug (68) and Connecting Flange (69) object of this
invention is to propose an improved steam conditioning valve super critical parameters
of steam in a turbine-bypass system for supply water; and object of this invention is
to propose an improved steam conditioning valve super critical parameters of steam
in a turbine-bypass system is made of F-91 material.
-a plurality of grooves configured on the valve stem (2) to divide the incoming steam is
divided into a number of discrete paths which allows nullifying the aerodynamic effects
as the steam impact on the valve components
The Penstock (80) is having several deep drilled minute holes around the pheriphery
in two rows. Spray water with high pressure is injected through the holes in to the
zone of steam with high velocity and turbulence, which enables atomization of the
spray water and a thorough mixing of water with the incoming steam for instant
desuperheating.
The jet Cage (9) is having a complementary profile with holes around the pheriphery,
which enables breaking of the steam jets into multiple small jets. This also prevents
water droplets reaching the pressure boundary wall and thus eliminates the thermal
shocks.

The Pressure Seal plug (68) accommodate the Penstock (80) and jet cage (9) along
with the body (3) and secure them together by means of a plurality of fasteners. (31,
47,48,49,67, 203)
Following is the parameters of steam and spray water that is handle by this valve.
Steam inlet Pressure 276 Kg/Sq.Cm
Steam inlet Temperature 568 Deg.C
Steam outlet pressure 74 Kg/Sq.Cm
Steam outlet Temperature 525 Deg.C
Spray water temperature 300 Deg.C
Spray water pressure 350 Kg/Sq.Cm
The present invention is able to achieve fine atomization of spray water and thorough
mixing of steam and quick and complete evaporation is achieved in the system.
Therefore erosion of boundary walls caused by high velocity droplets is eliminated.
The valve is suitable for frequent start up.

WE CLAIM:
1. An improved steam conditioning Valve operable at supercrital parameters of steam
in a turbine bypass system, comprising:
a valve body (1) having two hemisphere shaped bellies made of material SA 182 F91;
at least one inlet Nozzle (F-91) and a plurality of outlet Nozzles (F-91) welded to the
valve body (1);a spool piece (F22 material) welded with full penetration at an extreme
end of the outlet nozzle; the valve body (1) being stress relived after welding and then
machined to a final dimension.
-a Valve Seat (3) made of F-91 material with stellite cladding (S-CoCr20W15Ni), the
valve seat (3) weldably fixed to the valve body (1); and firmly secured and welded.
-a Stem (2) produced of material X19CrMoNbN11-1, and machined to a matching
profile of the valve body (1);
-a Jet cage (9) machined and drilled from F-91 material and provided with holes
including stellite cladding;
-a Penstock (80) formed of F-91 material cladded with S-Co65Cr25W, and having a
plurality of holes;
-a Gland bush (43) made of Monel K500 material;
-a Gland Retainer (41) made of Sa 182 F6a cl.3 material;

-One each Pressure Seal Plug (68) and Connecting Flange (69) object of this
invention is to propose an improved steam conditioning valve super critical parameters
of steam in a turbine-bypass system for supply water; and object of this invention is
to propose an improved steam conditioning valve super critical parameters of steam
in a turbine-bypass system is made of F-91 material.
-a plurality of grooves configured on the valve stem (2) to divide the incoming steam is
divided into a number of discrete paths which allows nullifying the aerodynamic effects
as the steam impact on the valve components.
2. The valve therefore claim 1, wherein said plurality of holes configured on the
penstock (80) constituting several deep-drilled minute holes configured in two rows
around the periphery which allows atomizing the spray water and mixing with steam
for desuperheating the steam.
3. The valve therefore claim 1, wherein the holes on the jet cage (9) enables breaking
of the steam jets to eliminate thermal shock.
4. An improved steam conditioning Valve operable at supercrital parameters of steam
in a turbine bypass system as substantially described and illustrated herein with
reference to the accompanying drawings.

An improved steam conditioning Valve operable at supercrital parameters of steam in
a turbine bypass system, comprising a valve body (1) having two hemisphere shaped
bellies made of material SA 182 F91; at least one inlet Nozzle (F-91) and a plurality of
outlet Nozzles (F-91) welded to the valve body (1);a spool piece (F22 material) welded
with full penetration at an extreme end of the outlet nozzle; the valve body (1) being
stress relived after welding and then machined to a final dimension; a Valve Seat (3)
made of F-91 material with stellite cladding (S-CoCr20W15Ni), the valve seat (3)
weldably fixed to the valve body (1); and firmly secured and welded,
a Stem (2) produced of material X19CrMoNbN11-1, and machined to a matching
profile of the valve body (1);a Jet cage (9) machined and drilled from F-91 material
and provided with holes including stellite cladding; a Penstock (80) formed of F-91
material cladded with S-Co65Cr25W, and having a plurality of holes; a Gland bush
(43) made of Monel K500 material; a Gland Retainer (41) made of Sa 182 F6a cl.3
material; one each Pressure Seal Plug (68) and Connecting Flange (69) object of this
invention is to propose an improved steam conditioning valve super critical parameters
of steam in a turbine-bypass system for supply water; and object of this invention is to

propose an improved steam conditioning valve super critical parameters of steam in a
turbine-bypass system is made of F-91 material; a plurality of grooves configured on
the valve stem (2) to divide the incoming steam is divided into a number of discrete
paths which allows nullifying the aerodynamic effects as the steam impact on the
valve components.