# US 7,744,343 B2 · Method and apparatus for controlling the operation of a steam turbine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,744,343 B2 - Document ID: US7744343B2 - Status: Granted - Kind: B2 - Application number: 11/534,170 - Filed: 2006-09-21 - Published: 2008-03-27 - Granted: 2010-06-29 - Earliest claimed: 2006-09-21 - Assignees: General Electric Company - Inventors: Steven Sebastian Burdgick; Boris Ivanovitch Frolov - Web page: https://patentgrep.com/patent/US7744343B2 ## CPC - F01D 11/10: using sealing fluid, e.g. steam - F01D 11/005: {Sealing means between non relatively rotating elements} - F01D 11/04: using sealing fluid, e.g. steam - F01D 11/06: Control thereof - F05D 2220/31: in steam turbines - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A steam turbine includes, in one exemplary embodiment, a rotor and a plurality of bucket stages coupled to the rotor with each bucket stage including a plurality of circumferentially spaced buckets coupled to the rotor. The steam turbine also includes a diaphragm assembly surrounding the rotor and the bucket stages, and an outer casing disposed about the rotor and diaphragm assembly. The diaphragm assembly includes a plurality of nozzle stages located between the bucket stages, a circumferentially extending groove, with the groove located upstream of one of the bucket stages and between that bucket stage and an adjacent nozzle stage, a circumferentially extending extraction chamber, and at least one first bore extending from the groove to the extraction chamber. The diaphragm assembly also includes at least one second bore extending from the extraction chamber through an outer surface of the diaphragm assembly. ## Claims ### Claim 1 A steam turbine comprising: a rotor; a plurality of bucket stages coupled to said rotor, each said bucket stage comprising a plurality of circumferentially spaced buckets coupled to said rotor, each said bucket comprising a base portion and a tip portion; a diaphragm assembly surrounding said rotor and said bucket stages; and an outer casing disposed about said rotor and diaphragm assembly; said diaphragm assembly comprising: a plurality of nozzle stages located between said bucket stages; a circumferentially extending groove, said groove located upstream from one of said bucket stages and between said bucket stage and an adjacent nozzle stage positioned upstream from said bucket stage; a circumferentially extending extraction chamber; at least one first bore extending from said groove to said extraction chamber, said at least one first bore providing bi-directional fluid communication between said groove and said extraction chamber; and at least one second bore extending from said extraction chamber through an outer surface of said diaphragm assembly; said at least one second bore providing bi-directional fluid communication between said extraction chamber and an area between said outer surface of said diaphragm assembly and said outer casing. ### Claim 2 (depends on 1) A steam turbine in accordance with claim 1 wherein said groove comprises a slot. ### Claim 3 (depends on 1) A steam turbine in accordance with claim 1 wherein said groove comprises a substantially scoop shape. ### Claim 4 (depends on 1) A steam turbine in accordance with claim 1 wherein said groove comprises a slot connected to an outer pocket, said at least one first bore extending from said outer pocket to said extraction chamber. ### Claim 5 (depends on 1) A steam turbine in accordance with claim 1 wherein said groove is located upstream of a last bucket stage. ### Claim 6 (depends on 1) A steam turbine in accordance with claim 1 wherein the area between the outer surface of the diaphragm assembly is in flow communication with a condenser. ### Claim 7 A diaphragm assembly for a steam turbine, the steam turbine including a rotor and a plurality of bucket stages coupled to the rotor, said diaphragm assembly comprising: a plurality of nozzle stages configured to be positioned between the bucket stages; a circumferentially extending groove, said groove located upstream from one bucket stage and between the one bucket stage and a nozzle stage that is positioned upstream from the bucket stage and adjacent to the one bucket stage; a circumferentially extending extraction chamber; at least one first bore extending from said groove to said extraction chamber, said at least one first bore providing bi-directional fluid communication between said groove and said extraction chamber; and at least one second bore extending from said extraction chamber through an outer surface of said diaphragm assembly; said at least one second bore providing bi-directional fluid communication between said extraction chamber and an area outside of said diaphragm assembly. ### Claim 8 (depends on 7) A diaphragm assembly in accordance with claim 7 wherein said groove comprises a slot. ### Claim 9 (depends on 7) A diaphragm assembly in accordance with claim 7 wherein said groove comprises a substantially scoop shape. ### Claim 10 (depends on 7) A diaphragm assembly in accordance with claim 7 wherein said groove comprises a slot connected to an outer pocket, said at least one first bore extending from said outer pocket to said extraction chamber. ### Claim 11 (depends on 7) A diaphragm assembly in accordance with claim 7 wherein said groove is located upstream of a last bucket stage. ### Claim 12 A method of controlling the operation of a steam turbine, the steam turbine comprising a rotor, a plurality of bucket stages coupled to the rotor, and an outer casing disposed about the rotor, each bucket stage comprising a plurality of circumferentially spaced buckets coupled to the rotor, each bucket comprising a base portion and a tip portion; said method comprising: providing a diaphragm assembly to surround the rotor and bucket stages, the diaphragm assembly comprising: a plurality of nozzle stages located between the bucket stages; a circumferentially extending groove, the groove located upstream from one of the bucket stages and between that bucket stage and an adjacent nozzle stage positioned upstream from the bucket stage; a circumferentially extending extraction chamber; at least one first bore extending from the groove to the extraction chamber, the at least one first bore providing bi-directional fluid communication between the groove and the extraction chamber; and at least one second bore extending from the extraction chamber through an outer surface of the diaphragm assembly; the at least one second bore providing bi-directional fluid communication between the extraction chamber and an area between the outer surface of the diaphragm assembly and the outer casing. ### Claim 13 (depends on 12) A method in accordance with claim 12 further comprising delivering external cooling steam to tip portion of the buckets of a bucket stage by passing cooling steam from the area between the outer surface of the diaphragm and the outer casing through the at least one second bore, through the extraction chamber, through the at least one first bore, through the groove and into the main steam flow cavity to cool the bucket stage during low steam flow operating conditions. ### Claim 14 (depends on 12) A method in accordance with claim 12 further comprising removing moisture through the groove, through the at least one first bore, through the extraction chamber, through the at least one second bore and into the area between the outer surface of the diaphragm assembly and the outer casing during steady state operating conditions. ### Claim 15 (depends on 14) A method in accordance with claim 14 wherein the area between the outer surface of the diaphragm assembly is in flow communication with a condenser. ### Claim 16 (depends on 12) A method in accordance with claim 12 further comprising removing steam through the groove, through the at least one first bore, through the extraction chamber, through the at least one second bore and into the area between the outer surface of the diaphragm assembly and the outer casing during high back pressure operating conditions. ### Claim 17 (depends on 12) A method in accordance with claim 12 wherein the groove comprises a slot. ### Claim 18 (depends on 12) A method in accordance with claim 12 wherein the groove comprises a substantially scoop shape. ### Claim 19 (depends on 12) A method in accordance with claim 12 wherein the groove comprises a slot connected to an outer pocket, the at least one first bore extending from the outer pocket to the extraction chamber. ### Claim 20 (depends on 12) A method in accordance with claim 12 wherein the groove is located upstream of a last bucket stage.