Flow Measurement

Non-invasive Flow Measurement With Clamp-on Ultrasonic Sensors In Titanium Dioxide Production

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Clamp-on Versus Vortex

Clamp-on ultrasonic technology is not limited to flow measurement applications involving aggressive or abrasive media. It is a good solution whenever users are looking for ways of avoiding downtime. A vortex flow meter, which was installed to monitor boiler feed water flow, was causing problems. The filter salts separated out during the sulfuric acid recycling process are broken down at crenox in a fluidized-bed furnace. The waste heat is routed to a boiler and then fed into the steam distribution network at the chemical park.

The flow of feed water to the boiler must be constantly monitored to ensure that sufficient cooling capacity is available for the fluidized-bed furnace. Because fluctuating pressures and temperatures up to 35 bar and 260 °C caused extreme wear, the service life of the vortex flow meter was inadequate. The system had to be shut down for days at a time to repair or replace the vortex flow meter, and that was a costly exercise.

It was no surprise that the crenox engineers approached Heinrich Brucks again when they needed a flowmeter system that can deliver dependable results for an extended period. For his part, Heinrich Brucks was glad that he did not have to say: “Sorry, but ultrasonic flowmeters don’t work at 250 °C.”

Flexim has developed the WaveInjector for high-temperature applications. The principle of operation of the patented device is simple yet very effective. The sensors on the WaveInjector are thermally insulated from the heat of the pipe while still ensuring excellent acoustic contact. This is achieved through the use of two steel coupling plates which connect the pipe and sensors but hold them apart. The plates dissipate enough heat, so that the temperature at the sensor mounting point remains within the allowable range.

The WaveInjector extends the application range of clamp-on ultrasonic technology to as much as 400 °C, retaining the obvious advantages of non-invasive flow measurement, namely no wear caused by the medium, exceptional dynamic performance and no work needed on the pipes. Clamp-on sensors stay on the safe side so to speak, namely on the outside where they are not affected by pressure inside the pipe. Installation of a high-temperature system to detect the flow of boiler feed water was completed during ongoing operation.

All that was needed was a bit of care and above all gloves for the work at the hot pipes. A comparison with the vortex flow meter, which is still installed in close proximity, is enough to convince even the most incorrigible skeptic. The differences in the results from the two flowmeters are insignificant.

* The author works at Flexim in Berlin/Germany.

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