Technology for signal transit time to be measured accurately in real stack conditions

FlueSonic® ultrasonic technology measures the time of flight of ultrasonic signals between two transducers.

Each transducer emits an ultrasonic pulse where the time of flight of ultrasonic signals sent between the transducers in the direction of flow is measured and compared to that from the pulses in the opposite direction against the flow. The difference in transit time of the pulses is directly proportional to the velocity of the flue gas. The stack flow velocity in the measurement path is calculated from the upstream and downstream transit time in a way that is independent of the actual speed of sound in the gas, flue gas temperature or pressure of flue gas composition.

ENVEA FlueSonic® instruments include Automated Reference Checks:

• Lower and Upper Reference (Zero and Span) sensor self-checks, a requirement of EN 16911-2
• Self-checks assess not only the performance of the electronics and measurement algorithm, but also the performance and correct operation of the transducers, including their ability to transmit, receive and discriminate actual ultrasonic signals from noise and offsets in the stack environment
• These automatic Quality Assurance features provide outputs which can be used for QAL 3 reporting requirements, as defined in EN 16911-2 and provide feedback to the user on the correct operation of the instrument