Flow and Concentration Measurement of Nitric Acid at a Filling Station
At an automatic filling station of a production plant of nitric acid, tank lorries are filled with either 68% or 60% concentrated acid. If the lower concentration is required, the 68% nitric acid has to be diluted by adding water. In order to ensure that the desired concentration is maintained, either density and temperature measurements or a direct concentration measurement is required.
Furthermore, a flow measurement is necessary for the monitoring of the tank lorries filling rate. A Coriolis meter, which was previously used to determine the density and mass flow proved to be unreliable, sensitive to wear and subsequently prone to leaking due to the strong corrosiveness of the acid.
Clamp-on ultrasonic concentration measurement with FLEXIM's PIOX S process analyser proved to be the superior solution for this measuring task. In the monitored concentration and temperature range (50 to 70 M%, T > 10°C), a distinctive relation of the media's sonic velocity can be drawn to its concentration levels.
Since the ultrasonic transducers are simply attached to the outside of the pipe and do not get in contact with the aggressive medium, they are not subject to any abrasion or corrosion and can never be a risk for leaks.
As the mediums density can be computed out of the measured concentration levels and the temperature (pressure if needed), PIOX S also allows for the monitoring of the mass flow rate by factoring in the measured volumetric flow rates. It is thus a better alternative to the Coriolis meters - especially at such demanding environments.
Advantages
- Precise and reliable non-invasive concentration and mass flow measurement
- No risk of leaks caused by the caustic and poisonous (when inhaled) nitric acid
- Highest level of adaptability to future changes in the facility
- Measuring system with robust design, developed for harsh industrial environments.
