Acoustic gas temperature measurement
Acoustic gas measurement is a contactless measurement method. It is optimized for use in a power plant, and is usable for temperatures up to 2000 °C. For application in all sorts of temperature monitoring projects in power plants, the institute has an acoustic gas temperature measurement system. The measurement system is used in the framework of various research projects in power plants. The system is mainly based on the temperature dependency on the speed of sound.
In practice, the speed of sound is determined through the so-called “time of flight” of a sound pulse. Through a known distance between the two measuring points, the average sound velocity can be determined. To this end, an air pressure powered sound signal is used, which lies in the frequency range of 200 to 3000 Hz. The sound signal runs from the sender to the receiver, and is recorded on both ends with a piezoelectric microphone. Subsequently, both digitalized signals are processed using a cross correlation to determine the term of the pulse.
For the determination of individual temperatures, two sending and receiving systems are necessary. The system can provide a maximum of eight analog individual temperatures. There does however exist the possibility that multiple sending/receiving systems are set up together, through which a defined number of temperature measurements can be determined. This number is dependent on the number of installed sending/receiving systems. For these measurements, the steam generator can determine the signal temperature distribution on one plane of the steam generator through a post-processing, which will then provide insight into the state of operations.