Flow and Concentration Measurement of Nitric Acid
Nitric acid production plants use tankers to transport the product from one site to another, 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.
A flow measurement is necessary for the monitoring of the tank lorries filling rate. A Coriolis flow meter is usually the meter of choice, with the ability to measure the density and mass flow directly.
This can be problematic and expensive and even with Hastelloy C Coriolis tubes the material is sensitive to wear and can leak due to the corrosiveness of the acid.
Clamp-on ultrasonic concentration measurement with FLEXIM's PIOX S process analyser has proven to be the 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.