GAS TURBINE PERFORMANCE CODES BASIC INFORMATION AND TUTORIALS

Performance Codes used to Measure Turbine

Performance analysis is not only extremely important in determining overall performance of the cycle but also in determining life cycle considerations of various critical hot section components.

The following three ASME Test Codes govern the test of a Gas Turbine Power Plant:

ASME, Performance Test Code on Overall Plant Performance, ASME PTC 46 1996, American Society of Mechanical Engineers 1996 2.

ASME, Performance Test Code on Test Uncertainty: Instruments and Apparatus PTC 19.1, 1988
3. ASME, Performance Test Code on Gas Turbines, ASME PTC 22 1997, American Society of Mechanical Engineers 1997.

The ASME, Performance Test Code on Overall Plant Performance, ASME PTC 46, was designed to determine the performance of the entire heat cycle as an integrated system. This code provides explicit procedures for determination of power plant thermal performance and electrical output.

The ASME, Performance Test Code on Test Uncertainty: Instruments and Apparatus PTC 19.1 specifies procedures for evaluation of uncertainties in individual test measurements, arising from both random errors and systematic errors, and for the propagation of random and systematic uncertainties into the uncertainty of test results.

The various statistical terms involved are defined. The end result of a measurement uncertainty analysis is to provide numerical estimates of systematic uncertainties, random uncertainties, and the combination of these into a total uncertainty with an approximate confidence level.

This is especially very important when computing guarantees in plant output and plant efficiency.
The PTC 22 establishes a limit of uncertainty of each measurement required;

the overall uncertainty must then be calculated in accordance with the procedures defined in ASME PTC 19.1 Measurement Uncertainty. The code requires that the typical uncertainties be within a 1.1% for the Power Output, and 0.9% in the heat rate calculations.

It is very important that the post-test uncertainty analysis should also be performed to assure the parties that the actual test has met the requirement of the code.

The instrumentation will be calibrated as per the requirements of the test codes. All the instrumentation must be calibrated before a test and certified that they meet the code requirements. The ASME PTC 19 series outlines the governing requirements of all instrumentation for an ASME Performance Test to be within the governing band of uncertainty.