Description:FIELD OF INVENTION
The present invention disclosure generally relates to a device and a method for pressure reduction of start-up vent steam for high pressure and high temperature steam generators of thermal power plant.

BACKGROUND OF THE INVENTION

Steam generators are generally used in once through super critical power generation plants. Initiation of this type of steam generator is done through start up and warmup system below the critical pressure of water.

During initial start-up operation of once through super critical boilers, the super-heated steam generated may not have the required pressure and temperature to allow the steam to expand in the turbine, if admitted in to the turbine because of expansion, condensation occurs and turbine blades get damaged. Therefore, the low quality steam is exhausted out to the atmosphere through start up vent. Huge volume of steam with high pressure to be vent out.

As merely exhausting the steam to the atmosphere produce high level noise, a silencer is used to keep the noise level below the limits that conforms to OHSAS standard requirements. But, steam to be exhausted will be around 81 Kg/cm2 pressure which is far above the maximum pressure that a silencer could withstand. So the pressure of super-heated steam which is 81 Kq/sq.cm in the vent line should be reduced below 3 kg/sq.cm before admitting to the silencer.

US9784137B2 titled “Subcritical pressure high-temperature steam power plant and subcritical pressure high-temperature variable pressure operation once-through boiler” discuss about a subcritical pressure high-temperature steam power plant includes a combustion boiler system, steam turbine generator system, and condensate and feedwater system and wherein the conditions of steam generated in the boiler system and supplied to the steam turbine generator system are subcritical pressure and high temperature (turbine inlet temperature of 593° C. or more).

US 3675733A titled “Pressure safety release industrial air exhaust silencer” discusses an air exhaust silencer comprises a barrel which has a piston head, the barrel is contained for reciprocation within a cylinder and is normally retained in the cylinder in an inwardly retracted position so as to permit air exhaust through the silencer structure supported within the barrel and which embodies a pair of gas permeable frequency distorters adapted to muffle the noise of the exhaust air to below a predetermined maximum noise level; the barrel containing cylinder of the silencer is provided with a plurality of relief ports which are in open communication with a normally closed off relief chamber in front of the piston head; regulated fluid pressure retaining means are employed to normally retain the barrel in the retracted position; upon build-up of back pressure in the silencer assembly, due to clogging of the gas permeable members of the silencer, the increased air pressure through the silencer becomes sufficient to move the barrel of the silencer out of the cylinder overcoming the magnitude of the fluid pressure retaining means to establish communication between the relief chamber and the inlet port of the silencer to thereby permit air pressure to bypass said clogged gas permeable members of the silencer for direct passage to the atmosphere.

None of the above cited prior art discusses the issues related to pressure reduction from high range to low range and to handle high range of steam flow simultaneously.
The present invention is directed to overcoming one or more problems set forth above and/or other problems associated with known devices for pressure reduction.

OBJECTS OF THE INVENTION

It is therefore a principal object of the present invention is to provide a device and method to reduce the pressure from 81 Kg/sq.cm to less than 3 Kg/sq.cm such that at the inlet of the silencer pressure be less than 3 Kg/sq.cm.

Another object of the present invention is to develop a device which ensures the steam flow of 40 TPH (tons per hour) without back flow during pressure reduction.

These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.

SUMMARY OF THE INVENTION

This summary is provided to introduce concepts related to a device and method for pressure reduction of start-up vent steam for high pressure and high temperature steam generators of thermal power plant.

The present invention relates to a device and method for reducing the pressure of start-up vent steam. The pressure reduction device comprises a plurality of expanders and a plurality of orifice plates having orifice holes through which the steam passes successively. Each orifice plates having orifice holes in a specific pattern. One or more stages having at least one expander and at least one orifice plates welded together through which the steam passes from an inlet connection pipe. An outlet connection pipe is inserted to a silencer inlet through which the steam passes and the pressure reduction is carried out depending on the different arrangement of orifice holes in the plurality of orifice plates.

In an aspect the diameter of orifice holes, number of orifice holes and pattern of orifice holes are designed at each stage of welding of the plurality of orifice plates with a plurality of expanders.

In an aspect the pressure reduction devices reduces pressure from 81 Kg/sq.cm to 2.53 Kg/sq.cm and handle 40 TPH flow of steam with 430 deg C.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:

FIG. 1 illustrates in cross-section view of a pressure reduction device in an embodiment of the present invention;

FIG. 2 is a top view of a first stage orifice plate arranged in the pressure reduction device in an embodiment of the present invention;

FIG. 3 is a top view of a second stage orifice plate arranged in the pressure reduction device in an embodiment of the present invention;

FIG. 4 is a top view of a third stage orifice plate arranged in the pressure reduction device in an embodiment of the present invention;

FIG. 5 is a top view of a fourth stage orifice plate arranged in the pressure reduction device in an embodiment of the present invention; and

FIG. 6 is a top view of a fifth stage orifice plate arranged in the pressure reduction device in an embodiment of the present invention.

The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.

The present invention relates to a device (100) and method for pressure reduction of start-up vent steam for high pressure and high temperature steam generators of thermal power plant.

FIG. 1 illustrates in cross-section view of a pressure reduction device (100) in an embodiment of the present invention. The pressure reduction device (100) consists of a plurality of expanders (01, 03, 05, 07, 09, 10) and a plurality of orifice plates (02, 04, 06, 08, 11) which are welded between the plurality of expanders (01, 03, 05, 07, 09, 10), an inlet outlet connection (13) and an outlet connection pipe (12). In a preferred embodiment the pressure reduction device (100) reduces the pressure from 81 kq/sq.cm to below 2.53 kg/sq.cm and capable of handling steam pressure of 40 TPH (tons per hour) flow. In one embodiment the plurality of expanders (01, 03, 05, 07, 09, 10) and plurality of orifice plates (02, 04, 06, 08, 11) configured with suitable orifice holes in a specific pattern which is used to reduce the pressure. In an embodiment the inlet connection pipe (13) of the pressure reduction device (100) is 3.5 inch and the outlet connection pipe (12) is 14 inch. The inlet connection pipe (13) is welded to a main steam line stub and the outlet connection pipe (12) is inserted in to a silencer inlet. (Not shown)

In one embodiment the diameter of orifice holes, number of orifice holes and pattern of orifice holes of the plurality of orifice plates (02, 04, 06, 08, 11) are designed at each stage of configuring the plurality of orifice plates (02, 04, 06, 08, 11) in such a way to reduce pressure from 81 Kg/sq.cm to 2.53 Kg/sq.cm. The pressure reduction device (100) is capable of handling 40 TPH flow of steam with 430 deg C as inlet temperature and also the flow is maintained with in sub sonic range throughout the pressure reduction process. In a preferred embodiment the pressure reduction device (100) is installed to a thermal power plant having super heater start up vent line and the pressure reduction device (100) reduces the pressure to a minimal level. The pressure reduction device (100) is robust enough to perform satisfactorily at high temperatures.

For example, sample calculation for the stage 1st orifice plate (02) is illustrated below:

Sample Calculation for stage – 1 orifice
Upstream Pressure = 81.0 Kg/cm2
Upstream Temperature = 430°C
Maximum Flow = 80 TPH
Two Start up vent, so the flow per vent = 40 TPH
Stage:I Condition: 1
Pressure = 81.0 Kg/cm2
Temperature = 430°C
Density = 27.443 Kg/m3
Sp. volume = 0.0364 m3/Kg
Enthalphy = 3219.12 KJ/Kg
Dynamic Viscosity = 0.02575 Centipoise
Pressure Drop ratio = 0.5 assumed
P1 = 81.0 Kg/cm2
P2 = 81.0 * 0.5 = 40.5 Kg/cm2

Diameter of pipe in which Orifice plate is fitted 108 mm
= 108 – (2 x 16)
Internal Diameter = 108 – (2 x 16) = 76 mm
Flow x Specific Volume
Velocity = -----------------------------------------
Area

Specific Volume at Condition 1 = 0.0364 m3/Kg
(0.076)2
Area = p x ------------- = 4.534 x 10-3 m2
4
Velocity = 89.20 m/sec.

Viscosity at Condition 1 = 0.02575 cp

þvd
Renolds Number = ---------------
µ
Where
þ = Density in Kg/m3
v = Velocity in m/sec
d = Pipe diameter in mm
µ = Dynamic viscosity in centipoise
27.443 x 89.2 x 76
Re = ---------------------------- = 7.2 x 106
0.02575

Orifice hole dia
? = ---------------------------------------------
Internal diameter of pipe

32 mm
? = ------------------ = 0.42
76 mm

From Crane Book Page A-20
for ? = 0.42

Pressure Ratio = ?P/P1 = 0.5

Y – Expansion Factor = 0.835 (Approx)

Flow Coefficient C
For Re = 7.2 x 106
? = 0.42
C = 0.605 (Approx)

Flow through Orifice hole diameter
p d22 2 (P1 – P2)
= CY ---------- -------------- = m3 / sec
4 þ

d2 = 32 mm

D2 = Orifice hole diameter in m
(P1 – P2) = Pressure drop in Pa.
þ = Density in Kg/m3
Flow through orifice hole of dia 32 mm = 0.218 m3/sec.
Flow through Orifice of hole diameter 32 mm = 0.218 x 27.443 = 5.99 Kg/sec.

Q = 21564 Kg/hr
Total flow = 40,000 Kg/hr
Flow through 32mm hole orifice = 21564 Kg/hr
Remaining flow = 40000 – 21564 = 18436 Kg/hr.

First PCD
Orifice diameter = 15 mm
? = 15/76 = 0.19
Expansion factor ‘Y’ = 0.84
Flow Coefficient C = 0.595

Flow through Orifice hole diameter
p d22 2 (P1 – P2)
= CY ---------- -------------- = m3 / sec
4 þ

d2 = 15 mm

(152 x 10-6) 2 x 40.5 x 9.8 x 104
= 0.595 x 0.84 x p x ----------------- -----------------------------
4 27.443

Flow through orifice hole of dia 15mm = 0.047 m3/sec.
Flow through Orifice of hole diameter 15 mm = 0.047 x 27.443 = 1.28 Kg/sec.

= 0.047 x 27.443 x 3600 = 4643.3 Kg/hr.

Flow through 32mm orifice hole = 21564 Kg/hr.

Flow through 15mm orifice hole = 4643.3 Kg/hr.

Total flow = 40,000 Kg/hr.

40000 – 21564 Minimum No. of 15mm orifice holes required = -------------------------- = 4
4643.3

Provided 6 holes.

First PC diameter is 56 mm.

Calculation orifice plate thickness

Checking for Bending stress:
Plate Material = SA 387 Gr.22
Design Pressure = 1.1 x operating pressure
= 1.1 x 81 = 89.1 Kg/cm2

Design Temperature = 1.1 x 430°
= 473°C

Allowable stress at 473°C = 10.311 Kg/mm2 = 1031.1 Kg/cm2
Checking in Bending

t = FG/2 P / S

F = 0.8 constant

G = Orifice Plate diameter = 108 mm

P = Design Pressure in Kg/cm2 = 89.1

S = Allowable stress in Kg/cm2 = 1031.1 Kg/cm2

T = Thickness in mm

= ( 0.8 x 10.8 ) / 2 x 89.1 / 1031.1 = 12.69 mm

Checking Thickness in Shear Stress:
T Shear = ( ( ( 0.31 x DL ) / ~ ) x ( P / S ) )
DL = (4 x A ) / C
A ? Area enclosed by Polygon Perimeter
C ? Perimeter of Polygon formed
~ ? Ligament Efficiency
A = (1/2 x b x h x 6)
A = (1/2 x 27.83 x 24.2 x6)
A = (4040.916 / 2)
A = 2020.458 m2
C = 27.83 x 6
C = 166.98
DL = (4 x A ) / C
DL = (4 x 2020.458 ) / 166.98
DL = 48.4
~ = ( ( x – 15 ) / x ) )
~ = ( ( 27.83 – 15 ) / 15 ) )
~ = 0.855
T Shear = ( ( ( 0.31 x 48.4 ) / 0.855 ) x ( 89.1 / 1031.1 ) )
T Shear = 1.516 mm

Check for Mach No – Sub Sonic flow.

Mach number calculated has to be less than 0.4

C/Z = Mach No.

C = Velocity of steam in m/s

Z = Velocity of sound pressure wave in stream in m/s.

C = 353.632 x f x v/d2

f = Total mass flow in Kg/hr

v = Specific volume in cu.m/Kg

d = Inside diameter of reducer in mm.

353.632 x 40000 x 0.0364
C = ------------------------------------------------ = 89.142
762

89.142
Mach No. = ---------------- = 0.145 < 0.4,
613
Flow is sub sonic.

FIG. 2 is a top view of a first stage orifice plate (02) arranged in the pressure reduction device (100) in an embodiment of the present invention. Referring to FIG.1, one or more stages are shown in the pressure reduction device (100). In a preferred embodiment, steam of 40TPH enters through an expander C in the first stage. As shown in FIG.2, the first orifice plate (02) having orifice hole in the centre and six number of orifice holes are equally spaced in the outer PCD (pitch circle diameter), the pressure gets reduced to 40. 50kg/cm2 with subsonic flow. In a preferred embodiment the pressure reduction device (100) consists of small portion of the inlet connection pipe (13) welded with 1st expander (01) and the 1st expander (01) is welded with 1st orifice plate (02) in order to reduce the pressure and the pressure reduction ratio is 0.5. In one embodiment at the outlet of 1st orifice plate (02) the pressure is 40.5 Kg/sq.cm. The hole pattern and orifice hole diameters are designed to reduce the pressure from 81 Kg/sq.cm to 40.5 Kg/sq.cm.

FIG. 3 is a top view of a second stage orifice plate (04) arranged in the pressure reduction device (100) in an embodiment of the present invention. Referring to FIG.1, the steam of 40TPH enters through the expander C in the second stage. As shown in FIG.3, the second orifice plate (04) having orifice hole in the centre and six number of orifice holes are equally spaced in the outer PCD (pitch circle diameter), the pressure gets reduced to 20.25kg/cm2 with subsonic flow. In a preferred embodiment the 1st orifice (02) is welded with 2nd expander (03) and 2nd expander (03) is welded with 2nd orifice plate (04) which is designed for the pressure reduction ratio of 0.5. In one embodiment at the outlet of 2nd orifice plate (04) the pressure is 20.25 Kg/sq.cm. The hole pattern and orifice hole diameters are designed to reduce the pressure from 40.5 Kg/sq.cm to 20.25 Kg/sq.cm.

FIG. 4 is a top view of a third stage orifice plate (06) arranged in the pressure reduction device (100) in an embodiment of the present invention. Referring to FIG.1, the steam of 40TPH enters through the expander C in the third Stage. As shown in FIG.4, third orifice plate (06) having orifice hole in the centre and six number of orifice holes are equally spaced in the outer PCD (pitch circle diameter), the pressure gets reduced to 10.12kg/cm2 with no back flow. In a preferred embodiment the 2nd orifice (04) is welded with 3rd expander (05) and the 3rd expander (05) is welded with 3rd orifice plate (06) which is designed for pressure reduction ratio of 0.5. In one embodiment at the outlet of 3rd orifice plate (06) the pressure is 10.12 Kg/sq.cm. The hole pattern and orifice hole diameters are designed to reduce the pressure from 20.25 Kg/sq.cm to 10.12 Kg/sq.cm.

FIG. 5 is a top view of a fourth stage orifice plate (08) arranged in the pressure reduction device (100) in an embodiment of the present invention. Referring to FIG.1 the steam of 40TPH happens through the expander C in the fourth stage. In a preferred embodiment as shown in FIG.5, the fourth orifice plate (08) having orifice hole in the centre and seven numbers of orifice holes are equally spaced in the outer PCD (pitch circle diameter), the pressure gets reduced to 5.06kg/cm2 with no back flow. In a preferred embodiment the 3rd orifice (06) is welded with 4th expander (07) and 4th expander (07) is welded with 4th orifice plate (08) which is designed for pressure reduction ratio of 0.5. At the outlet of 4th orifice plate (08) the pressure is 5.06 Kg/sq.cm. The hole pattern and orifice hole diameters are designed to reduce the pressure from 10.12 Kg/sq.cm to 5.06 Kg/sq.cm.

FIG. 6 is a top view of a fifth stage orifice plate (11) arranged in the pressure reduction device (100) in an embodiment of the present invention. Referring to FIG.1, the steam of 40TPH happens through the expanders NB250/NB300 (09) and NB300/NB350 (10) where the inlet pressure is 5.06kg/cm2 with C in the fifth stage. In a preferred embodiment as shown in FIG.6, the fifth orifice plate (11) is welded next to the expander NB300/NB350 having six number of holes which are equally spaced in outer PCD (pitch circle diameter) and three numbers of orifice holes which are equally spaced in the inner PCD (pitch circle diameter), the pressure gets reduced to 2.53kg/cm2 with no back flow. In one embodiment the 4th orifice (11) is welded with two expander 5th (09) and expander 6th (10) respectively. The 6th expander (10) is welded with the 5th orifice plate (11) which is designed for pressure reduction ratio of 0.5. In a preferred embodiment at the outlet of 5th orifice plate (11) the pressure is 2.53 Kg/sq.cm. The hole pattern and orifice hole diameters are designed to reduce the pressure from 5.06 Kg/sq.cm to 2.53 Kg/sq.cm.

In one embodiment the 5th orifice plate (11) is again welded to the outlet connection pipe (12) which is a straight pipe of 14 inch that is inserted inside the silencer. In a preferred embodiment referring to FIG. 1, five stages of the plurality of orifice plates (02, 04, 06, 08, 11) with different arrangement of orifice holes are welded with the plurality of expanders (01, 03, 05, 07, 09, 10) and tested at high pressure and high temperature steam generator unit for the pressure reduction from 81.0kg/cm2 to less than 2.53kg/cm2 to facilitate the entry of steam into the silencer. The combination of the plurality of expanders (01, 03, 05, 07, 09, 10) and the plurality of orifice plates (02, 04, 06, 08, 11) are capable of handling 40 TPH flow of steam and Mach number maintained less than 0.4 to ensure the flow is sub sonic.

In one embodiment implementation of the method is shown by the example of the operation of the pressure reduction device (100). The method is implemented using the pressure reduction device (100) as follows. Step 1: Configuring a plurality of expanders (01, 03, 05, 07, 09, 10) and a plurality of orifice plates (02, 04, 06, 08, 11) having orifice holes through which the steam passes successively, each orifice plates (02, 04, 06, 08, 11) having orifice holes in a specific pattern than the preceding orifice plates. Step 2: Assembling at least one expander (01, 03, 05, 07, 09, 10) and at least one orifice plates (02, 04, 06, 08, 11) in one or more stages by welding together through which the steam passes from an inlet connection pipe (13). Step 3: Inserting an outlet connection pipe (12) to a silencer inlet that make a narrow passage through which the steam passes and the pressure reduction is carried out depending on the different arrangement of orifice holes in the plurality of orifice plates (02, 04, 06, 08, 11).

In one embodiment the pressure reduction device (100) is designed for pressure reduction from 81 Kg/sq cm to less than 3 kg/sq.cm and capable of handling 40 tonnes of steam flow. In a preferred embodiment the pressure reduction device (100) is designed with plurality of expanders (01, 03, 05, 07, 09, 10) and the plurality of orifice plates (02, 04, 06, 08, 11) to handle 40 tonnes of steam flow to reduce the pressure from 81kg/sq.cm to 2.53 Kg/sq.cm. In a preferred embodiment the pressure reduction device (100) is connected in the upstream of the silencer. The pressure reduction device (100) reduces the pressure from 81 Kg/cm2 at inlet to 2.53 Kg/cm2 at outlet in five stages of expanders and orifice plate assembly.

It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope. The present invention will now be described more specifically with reference to the following specification.

It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

Although embodiments for the present subject matter have been described in language specific to package features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.

Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:

1. A device (100) for reducing the pressure of start-up vent steam comprises:

a plurality of expanders (01, 03, 05, 07, 09, 10) and a plurality of orifice plates (02, 04, 06, 08, 11) having orifice holes through which the steam passes successively, wherein each orifice plates (02, 04, 06, 08, 11) having orifice holes in a specific pattern than the preceding orifice plates;

one or more stages having at least one expander (01, 03, 05, 07, 09, 10) and at least one orifice plates (02, 04, 06, 08, 11) welded together through which the steam passes from an inlet connection pipe (13) and

an outlet connection pipe (12) is inserted to a silencer inlet that make a passage through which the steam passes and the pressure reduction is carried out depending on the different arrangement of orifice holes in the plurality of orifice plates (02, 04, 06, 08, 11).

2. The device (100) as claimed in claim 1, wherein the diameter of orifice holes, number of orifice holes and pattern of orifice holes are designed at each stage of welding of the plurality of orifice plates (02, 04, 06, 08, 11) with a plurality of expanders (01, 03, 05, 07, 09, 10).

3. The device (100) as claimed in claim 1, configured to achieve pressure reduction from 81 Kg/sq.cm to 2.53 Kg/sq.cm.

4. The device (100) as claimed in claim 1, configured to handle 40 TPH (tons per hour) flow of steam with 430 deg C.

5. The device (100) as claimed in claim 1, configured to reduce pressure using the inlet connection pipe (13) dimension of 3.5 inch and outlet connection pipe (12) dimension of 14 inch.

6. The device (100) as claimed in claim 1, wherein the flow is maintained with in sub sonic range throughout the pressure reduction.

7. The device (100) as claimed in claim 1, configured to reduce pressure for high pressure and high temperature steam generators of thermal power plant.

8. A method for reducing the pressure of start-up vent steam comprising the steps of :

configuring a plurality of expanders (01, 03, 05, 07, 09, 10) and a plurality of orifice plates (02, 04, 06, 08, 11) having orifice holes through which the steam passes successively, each orifice plates (02, 04, 06, 08, 11) having orifice holes in a specific pattern than the preceding orifice plates;

assembling at least one expander (01, 03, 05, 07, 09, 10) and at least one orifice plates (02, 04, 06, 08, 11) at one or more stages by welding together through which the steam passes from an inlet connection pipe (13) and

inserting an outlet connection pipe (12) to a silencer inlet that make a passage through which the steam passes and the pressure reduction is carried out depending on the different arrangement of orifice holes in the plurality of orifice plates (02, 04, 06, 08, 11).