Defects in air heaters can be troublesome for their performance, sparking a multitude of longstanding additional problems. For example, excessive air leakage can be responsible for the degradation of the performance of downstream air pollution control equipment, increased heat rate, increased rate of cold end air heater basket corrosion, and increased potential for fires and explosives, among many other concerns. To continue its reliable standard procedures for conducting performance tests of air heaters, ASME PTC 4.3-2017 – Air Heaters has been revised.
ASME PTC 4.3-2017 is an performance test code (PTC) written, developed, and published by the American Society of Mechanical Engineers (ASME). These documents provide uniform rules and procedures for the planning, preparation, execution, and reporting of performance test results.
This performance test code, ASME PTC 4.3-2017, has been written and updated to provide guidelines for test procedures for air heaters that yield of the highest level of accuracy, due to its basis in the highest engineering knowledge. Specifically, the test procedures in the PTC can be used to determine the following:
- exit gas temperature
- air to gas leakage
- fluid pressure losses
- other fluid temperatures
It also provides procedures for determining the heat capacity ratio (X-ratio), which may be necessary under certain conditions.
The ASME PTC 4.3-2017 code applies to all air heaters used in industrial applications, specifically combustion gas-to-air heat exchanger-including air heaters with multisection air streams and air preheater coils utilizing noncondensing steam, water, or other hot fluids. It does not, however, cover direct-fired air heaters or gas-to-gas heat exchangers.
The content found within ASME PTC 4.3-2017 is extensive, addressing the test’s preparations and background information, the instruments used, methods of measurement, procedure for computing the results of the observations taken in the measurements, and ways to analyze uncertainty, with the use of figures as visual aides.
Work on this latest revision was conducted for several reasons, fulfilling the need to:
- include test uncertainty
- minimize the prescriptive guidelines and emphasize the performance-based approach
- address air heater configurations with multiple flow streams
- update measurement methods
- include improved instrumentation currently available
- base combustion calculations on O2 instead of CO2
- update nomenclature
- comply with ASME policy that SI units be used in publications
ASME PTC 4.3-2017 – Air Heaters is available on the ANSI Webstore.