Claims:WE CLAIM:
1. An LP exhaust hood spray system (100) comprising:
a piping routed inside LP Exhaust Casing, the piping having:
a pipe (1);
a Half round Pipe Assembly-Upper (2) and a Half Round Pipe Assembly-Lower (3) coupled to the pipe (1),
wherein, the Half round Pipe Assembly-Upper (2) and the Half Round Pipe Assembly-Lower (3) defines a circular profile installed in LP Exhaust on the LP Exhaust Diffuser (20), and wherein,
the piping routed inside the LP Exhaust Casing includes a plurality of nozzles (18) installed in a direction of steam flow.
2. The LP exhaust hood spray system (100) as claimed in claim 1, wherein the Half round Pipe Assembly-Upper (2) and the Half Round Pipe Assembly-Lower (3) are routed in between holes drilled in a Stiffening plate (19) arrangement and fixed on a Diffuser using Plate (7), Pipe clamp (8), Screw Hex (9) and Washer (10) at a plurality of locations.
3. The LP exhaust hood spray system (100) as claimed in claim 1, wherein the pipe (1), the Half round Pipe Assembly-Upper (2), and the Half Round Pipe Assembly-Lower (3) are coupled through a removable type connecting piece (4), a flange, and an Intermediate piece (6), and wherein the Intermediate piece (6) is designed to be installed at both ends of the Half round Pipe Assembly-Upper (2), and the Half Round Pipe Assembly-Lower (3), and the intermediate piece (6) being configured to be welded to an outer diameter of the pipe (1).
4. The LP exhaust hood spray system (100) as claimed in claim 3, wherein one end of the Half round Pipe Assembly-Upper (2) is connected to a water supply from a Supply line, and one end of Half Round Pipe Assembly-Lower (3) is Closed using a Dummy Flange (15) coupled with the intermediate piece (6).
, Description:LP EXHAUST HOOD SPRAY SYSTEM
FIELD OF INVENTION
[001] The present invention relates to LP Exhaust Hood Spray System. More particularly, the present invention relates to LP Exhaust Hood Spray for Russian design steam turbines to take care of unallowable high exhaust temperatures.

BACKGROUND OF THE INVENTION

[002] Steam turbine extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft to drive an electrical generator for generating electricity.

[003] In a typical larger power stations, the steam turbines are split into three separate stages, the first stage being the High Pressure (HP), the second stage the intermediate Pressure (IP) and the third the Low Pressure (LP) stage where high, intermediate and low describe the pressure of the steam. The High Pressure (HP) turbine module is the first turbine to receive steam from the main steam system, while Low Pressure (LP) turbine module is the last. The turbine in between the HP and LP is an intermediate Pressure (IP) Turbine module. These turbines are designed to efficiently extract work out of high pressure of the steam as steam passes through all the modules and converts thermal energy (high pressure and high temperature) of working fluid in to mechanical energy (as shown in Fig. 1).

[004] Due to stiff requirement of increase in capacity of old power plants it has become an engineering challenge to increase the rated power output of old existing thermal power plants by keeping the same turbine casings and footprints to avoid change in civil concrete structure available at location. In a similar requirement to increase the power output of thermal power plant will require change in LP bladed rotor and Bladed casings inside Turbine outer casing, and Pedestals and Turbine outer casings will remain same.
[005] The new design requires blading of KWU design mounted on a single machined forging. The blading of the LP turbine has been converted from Impulse design to reaction design and Baumann stage available in the existing LP Guide blade carrier is to be removed. The complete change in existing blade philosophy has made the turbine exhaust prone to higher exhaust temperatures.

OBJECTS OF THE INVENTION

[006] The present disclosure overcomes the above-mentioned problems, and an object of the present disclosure is to design an Exhaust hood spray system to avoid unallowable high temperatures in LP Exhaust.

SUMMARY OF THE INVENTION

[007] The present invention relates to an LP exhaust hood spray system (100) including a piping routed inside LP Exhaust Casing, the piping having a pipe (1); a Half round Pipe Assembly-Upper (2) and a Half Round Pipe Assembly-Lower (3) coupled to the pipe (1), wherein, the Half round Pipe Assembly-Upper (2) and the Half Round Pipe Assembly-Lower (3) defines a circular profile installed in LP Exhaust on the LP Exhaust Diffuser (20), and wherein, the piping routed inside the LP Exhaust Casing includes a plurality of nozzles (18) installed in a direction of steam flow.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[008] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:
Figure 1 shows: cross sectional view of the high rating steam turbine.
Figure 2 shows: 3-dimensional representation of Hood spray piping installed in LP Exhaust casing.
Figure 3 shows: the outer piping connection used to connect hood spray piping installed in Upper Half and Lower Half.
Figure 4 shows: 3-dimensional representation of Hood spray piping installed in Upper part of LP Exhaust casing.
Figure 5 shows: Side view of LP Exhaust Casing with Hood spray.
Figure 6 shows: Front view of LP Exhaust Casing with Hood spray.
Figure 7 shows: View U as shown in Figure 6.
Figure 8 shows: View V as shown in Figure 6.
Figure 9 shows: Cross section showing the Installation of nozzle in the pipe.
Figure 10 shows: arrangement of Connecting piece.
Figure 11 shows: installation of Pipe on the Exhaust diffuser using the pipe clamp.
Figure 12 shows: view in which pipe is passing through the diffuser Stiffening plates

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

[009] The present invention will now be described more specifically with reference to the following specification.

[0010] 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 1-12.

[0011] The present invention is contemplated with a view for avoiding unallowable high exhaust temperatures in LP Exhaust which can occur during normal course of operation, bypass operation or seal steam operation. To prevent an unallowably high temperatures caused by LP-ventilation a water injection system is installed at the Low-Pressure turbines. Condensate is injected into the steam via. Atomizer nozzles arranged in the ends of the LP Turbine casing. The cooling is carried out via. One stage injection of condensate via. 18 nos. nozzles arranged on a circular pipe fitted in the exhaust casing of LP Turbine. The exhaust hood spray system is installed on both Turbine side and Generator end of the LP Turbine.

[0012] The water injection valve is open when limit temperatures of the LP blading or LP Exhaust are exceeded. The water injection is closed when the temperatures fall down or a define turbine load is reached (in this case the mass flow through the turbine is so high that the blades are cooled sufficiently). For the turbine load the pressure before LP Blading is used as criterion. The steam temperature of LP Exhaust is measured as wall temperature of each casing top section and in the rear area of the LP Blading (Generator end).

[0013] The water injection is interlocked during the steam turbine crosses a certain turbine speed area in order to prevent vibration excitation of the free-standing end stage blades. To prevent the LP Turbine during turning operation from thermal load the LP Hood spray system is put automatically into action during bypass and /or seal steam operation. In addition to piping, throttle valves and monitoring equipment, the following components are included:
- LP Hood spray Injection Valve.
- Reducing Valve of LP Hood Spray.
- Filter of LP Hood Spray.

[0014] If cooling is insufficient at otherwise constant operating conditions, then it is possible that either the filter or the atomizer nozzles are contaminated. The subject matter disclosed herein relates to an LP Exhaust Hood Spray (100) for Russian design steam turbines to take care of unallowable high exhaust temperatures.

[0015] According to an implementation of the present subject matter, a novel method is specifically designed to take care of unallowable high exhaust temperatures. In accordance with an embodiment of the present disclosure, reference is made to the following figures and associated components.

[0016] The support arrangement comprises of following members:
- Pipe (1)
- Half round Pipe Assembly-Upper (2)
- Half Round Pipe Assembly-Lower (3)
- Connecting Piece (4)
- Flange (5)
- Plurality of Intermediate Piece (6)
- Plurality of Support Plate (7)
- Plurality of Pipe Clamp (8)
- Plurality of Screw Hex (9)
- Washer (10)
- Plurality of Screw Hex (11)
- Washer (12)
- Pipe Elbow (13)
- Dummy Flange (15)
- O Ring (16)
- Plug (17)
- Spray Nozzle (18)
- Stiffening Plate (19)
- LP Exhaust Diffuser (20)

[0017] In an embodiment, the LP Exhaust Hood Spray system (100) consist of piping routed inside LP Exhaust Casing in which nozzles (18) are installed in the direction of steam flow. The piping basically consists of two halfs to accommodate individually inside both halfs of LP Turbine i.e. Upper half and Lower half. The Upper half of Piping consists of 2nos. of Pipe (1) welded with Half round Assembly –Upper (2) using a Pipe Elbow (13) in between on both sides.

[0018] Similarly, The Lower half of Piping consists of 2nos. of Pipe (1) welded with Half round Assembly –Lower (3) using a Pipe Elbow (13) in between on both sides. A hole of required size at is drilled in Half round Assembly –Upper (2) at 8 locations and in Half round Assembly –Lower (3) at 10 locations. The angle between the locations of holes is decided based upon the space availability in LP Exhaust Casing (Refer Figure 6).

[0019] The two half of Piping assembly is installed in LP Exhaust on the LP Exhaust Diffuser (20). Holes are drilled in the Stiffening plate (19) arrangement designed inside the LP Exhaust Casing to direct the flow into condenser and to maintain the rigidity of the fabricated casing (Refer Figure 9). The Two half of piping assembly is routed in between the holes drilled in the Stiffening plate (19) arrangement (Refer Figure 12) and fixed on the Diffuser using Plate (7), Pipe clamp (8), Screw Hex (9) and Washer (10) at multiple locations. Each location is decided such that there is a fixing point on each side of the Nozzle (18).

[0020] The two halfs of piping installed individually in Upper half and Lower half of casing is to be coupled together to achieve continuity of flow of water inside the piping. Since there is requirement of lifting of upper half of casing during maintenance period it is not possible to connect both half of piping permanently by welding. Hence to resolve the problem a removable type connecting piece (4) is designed. Flange (5) of required size is connected on both side of the Connecting piece (4). An Intermediate piece (6) (Refer Figure 13) is designed to be installed at both ends of Upper half (1,2,1) and Lower half (1,3,1) of Piping Assembly. The intermediate piece (6) is welded to the outer diameter of the pipe (1). An O ring is placed in between the Intermediate Piece (6) and Flange (5) to avoid any leakage of water during operation. The two items are coupled together using Screw hex (11) and Washer (12).

[0021] One end of the Upper half assembly is connected to the water supply from the Supply line (Refer Figure 7). One end of the Lower half assembly is Closed using a Dummy Flange (15) coupled with the intermediate piece (6) as shown in Figure 8. The design and size of the nozzles are calculated based upon the total flow requirement of water to be sprayed and no. of ports available for spray. In case of fewer requirement of No. of spray nozzles Few of the holes can be plugged using Item Plug (17).

[0022] 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.

[0023] From the foregoing description, it will be appreciated that a system is designed for avoiding unallowable high exhaust temperatures in LP Exhaust which can occur during normal course of operation, bypass operation or seal steam operation.

[0024] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims.