Methods of measuring steam turbine efficiency

• US 7,634,385 B2
• Filed: 04/18/2005
• Issued: 12/15/2009
• Est. Priority Date: 05/22/2003
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Smith, Raub Warfield
• Primary Examiner(s): Lau; Tung S
• Application Number:
  US11/108,299
• Publication Number:
  US 20050182576A1
• Time in Patent Office: 1,702 Days
• Field of Search: 702/182
• US Class Current: 702/182
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F01K 23/101 Regulating means specially adapted therefor F01K23/105, F01K23/108 take precedence
• CPC Class Codes: F01K 23/16 all the engines being turbines F01K23/14 takes precedence
• CPC Class Codes: F01K 7/22 the turbines having inter-stage steam heating
• CPC Class Codes: F05D 2220/31 in steam turbines
• CPC Class Codes: F05D 2260/80 Diagnostics
• CPC Class Codes: G01L 3/26 Devices for measuring efficiency, i.e. the ratio of power output to power input
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

A method for measuring efficiency of a turbine includes operating the power plant at a first load, wherein a gas turbine is operated with a first fuel flow and a first gas turbine inlet air flow, determining a first shaft output at the first load with steam supplied from a heat recovery steam generator (HRSG) to both the first steam turbine inlet and the second steam turbine inlet, maintaining the first gas turbine fuel flow, the first gas turbine inlet air flow, and the first steam turbine inlet steam flow while isolating the second steam turbine from the steam admission flow, determining a second shaft output while the second steam turbine is isolated from the steam admission flow, and determining an expansion efficiency of the second steam turbine based on the first shaft output and the second shaft output and a measured change in second steam turbine admission steam flow.

Claims

1. A method for measuring expansion efficiency of a turbine within a power plant, said method comprising:

operating a Rankine cycle steam power plant including at least one steam turbine at a first load and a first HP throttle steam flow, the steam turbine including a first turbine with superheated exhaust and a second turbine with two phase exhaust and steam extracted to an extraction feedwater heater;

determining a first shaft output at the first load with steam extraction flow to the extraction feedwater heater from either a second steam turbine inlet or after partial expansion in the second steam turbine;

determining a second shaft output at the first load, the first HP throttle steam flow and the extraction from the second steam turbine to feedwater heating closed; and

determining an expansion efficiency of the second steam turbine using the first shaft output, the second shaft output, and a change in extraction steam flow from the second steam turbine.

2. A method in accordance with claim 1 wherein operating the at least one steam turbine at a first load and the first HP throttle flow, the steam turbine including at least a first turbine and a second turbine, the steam turbine further comprises a High Pressure/Intermediate Pressure (HP/IP) steam turbine and a Low Pressure (LP) steam turbine.

3. A method in accordance with claim 1 wherein determining an expansion efficiency of the second steam turbine comprises:

estimating an initial expansion efficiency of the second steam turbine; and

estimating a second expansion efficiency of the second steam turbine different than the initial turbine expansion efficiency.

4. A method in accordance with claim 1 further comprising measuring the LP turbine expansion efficiency using an iterative computer performance model also including calculated changes in the second steam turbine exhaust loss, generator losses, and feedwater heater extraction conditions.

5. A method in accordance with claim 3 wherein measuring an expansion efficiency of the second steam turbine is in accordance with: