Title of Invention

" A HIGH TEMPERATURE BEARING FOR GAS FLOW DIVERTOR

Abstract

The invention relates to a high-temperature bearing for gas flow divertor in which the bearing will not be prone to jamming caused by thermal expansion. The inner ring (8) is segmented in odd numbers and each segment will be free to expand in circumferential direction which will be accommodated in the angular gap left between segments. The contact zone between the inner ring (8) and the bearing housing (9) is symmetrical for superior self-aligning capability to the inner ring (8).

Full Text

This invention relates to a high temperature bearing for gas flow divertor of a combined-cycle power plant. In a combined-cycle power plant, a gas turbine is used to convert the heat generated in the combustion chamber into mechanical power, which drives the turbo-generator through a gear box and generates electrical power. The exhaust gases coming out of the turbine are very hot (operating temperature being more than 560°C). Part of this heat is recovered in the Heat Recovery Steam Generator (HRSG) and the steam generated herein is used for driving a steam turbine, which in turn drives a turbo-generator for generation of electrical power. As an option the steam generated in the HRSG can be used in a chemical process. The exhaust gases flow either to the Heat Recovery Steam Generator or chimney, in accordance with the operational requirements, and for carrying out repairs on HRSG side. The gas flow divertor is used to control the flow of exhaust gases. This is a very large valve (typical cross-sectional area being 10 sq.mtr.) and is subjected to temperatures in excess of 560°C of the exhaust gases. Hence thermal expansions of the components have to be considered in design. Further sealing arrangements have to have high efficiency for minimising loss of heat and protection of persons working for repairs. The gas flow divertor consists of a blade/flap mounted on two high-temperature bearings mounted on the main frame assembly. The blade is moved by an electric actuator through combined bevel and worm gear boxes. Seals are provided all around the blade assembly to ensure 100% sealing efficiency with the seal air system being operational. The bearing housing is mounted on the main frame assembly of the gas flow divertor by bolts through the holes in its flanges. The inner ring made of one piece has slots machined on its inner diameter to trap debris and the outer surface is spherical for self-alignment. mounted on said bearing housing and a a cover plate/ stopper, mounted on a flat surface machined in the inner surface of the bearing housing characterized in that said inner ring comprises of plurality of segments in odd numbers, each of said segments has a land portion on its inner diameter, the edges of said segments are in contact with each other and total included angle subtended by said segments and said stopper is less than 360°C which leaves a small angular gap between said segments. The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non-limiting exemplary expodiments of the invention represented in the accompanying drawings. Figure 1. A sectional elevation of Prior art arrangement of high-temperature bearing. Figure 2. A side elevation of Prior art arrangement of high-temperature bearing. Figure 3. A sectional elevation of arrangement of high-temperature bearing according to present invention. Figure 4. A side elevation of arrangement of high-temperature bearing according to present invention. The existing arrangement of the high-temperature bearing as shown in figure 1 & 2 consists of an inner ring (1), bearing housing (2) and a cover plate (3). The inner ring has slots (4) machined on its inner diameter for trapping any debris. The outer surface of the inner ring is spherical (5) to facilitate self-alignment of the bearing with the shaft in case of any misalignment due to thermal stresses. The inner ring is inserted into the bearing housing through a slot (6) and turned to make it seated in the inner spherical surface of the bearing housing. The cover plate (3) prevents the inner ring from coming out of the bearing housing. The bearing housing is mounted on the main frame assembly of the gas flow divertor by bolts through the holes in its flange (7). The high-temperature bearing according to the present invention as shown in figure 3 & 4 consists of inner ring with plurality of segments (8), bearing housing (9), cover plate ,(10) and a stopper (11) The number of segments (8) to be used is odd. The outer surface of the segments is spherical and is seated in a spherical surface machined in the bearing housing (9). Each segment (8) has a land portion on its inner diameter and material at the edges is removed for trapping any debris. The edges of the segments are in contact with each other. The total included angle subtended by the segments and the stopper is less than 360°, which leaves a small angular gap between the segments (8 ). The bearing housing (9) has a stopper mounted on a flat surface machined in its inner surface. The stopper (11) prevents rotation of the segments (8) alongwith the shaft when the blade is moved. The stem of the stopper (11) has a threaded portion in its lower part for fastening it to the bearing housing (9). The stopper (11) is mounted in the unloaded side of the bearing. The invention described hereinabove is in relation to a non-limiting embodiment and as defined by the accompanying claims. WE CLAIM: 1. A high temperature bearing for gas flow divertor used upto the high temperature of 560°C comprising an inner ring, the outer surface of said inner ring is spherical and is seated in a spherical surface machined in the bearing housing (9), a cover plate (10) mounted on said bearing housing (9) and a stopper (11) mounted on a flat surface machined in the inner surface of the bearing housing characterized in that said inner ring comprises of plurality of segments (8) in odd numbers, each of said segments (8) has a land portion on its inner diameter, the edges of said segments (8) are in contact with each other and total included angle subtended by said segments (8) and said stopper (11) is less than 360°, which leaves a small angular gap around 3° to 4° between said segments (8). 2. A high-temperature bearing for gas flow divertor as claimed in claim 1 wherein the stem of said stopper is provided with a threaded portion in its lower part for fastening it to said bearing housing. 3. A high-temperature bearing for gas flow divertor as claimed in claim 2 wherein said stopper is mounted in the unloaded side of the bearing to prevent the rotations of said segments alongwith the shaft when the blade is moved. 4. A high-temperature bearing for gas flow divertor as claimed in claim 1 wherein the radius of the spherical surface of the said inner ring is smaller than that of the said bearing housing surface for tilting and self-aligning property. 5. A high-temperature bearing for gas flow divertor as claimed in claim 1 wherein said segments are individually removable for service after the said cover plate is opened. 6. A high-temperature bearing for gas flow divertor as herein described and illustrated.

Documents:

90-del-1999-abstract.pdf

90-del-1999-claims.pdf

90-del-1999-complete specification (granted).pdf

90-del-1999-correspondence-others.pdf

90-del-1999-correspondence-po.pdf

90-del-1999-description (complete).pdf

90-del-1999-drawings.pdf

90-del-1999-form-1.pdf

90-del-1999-form-13.pdf

90-del-1999-form-19.pdf

90-del-1999-form-2.pdf

90-del-1999-form-3.pdf

90-del-1999-gpa.pdf