Chemistry - Product storage
Storage tanks come in all shapes and sizes. They are used for the storage of incoming (raw) materials, as intermediate storage or buffer tank. Of course, the final product is also stored in such tanks.
In many cases, a nitrogen blanket is applied on top of the stored product. This is an amount of nitrogen in the uppermost section of the tank that ensures that an explosion cannot occur in the tank, or to prevent the product from reacting with oxygen (oxidising) and therefore no longer meets quality standards. This technique is called inertisation. In this regard it’s important to measure whether there isn’t too much (or too little) oxygen present in that nitrogen atmosphere.
The quality or composition of the stored product is, of course, closely monitored. It may happen that the properties of the product change due to (too long) storage or changing circumstances (such as ambient temperature or moisture). That’s not the intention. Continuous product monitoring is therefore of the utmost importance.
- Oxygen analysis: Using a TDL (Tunable Diode Laser) gas analyser, one can flawlessly determine the oxygen content in the nitrogen atmosphere. Measurement takes place directly in the tank with this technique. If necessary, the analyser can be protected with filters against moisture and dust particles.
- Oxygen measurement: If conditions in the tank allow, you can monitor inertisation using simple oxygen sensors. This can be done with optical sensors as well as classical amperometric ones.
- Pressure and differential pressure measurement: The oldest technique to ensure that there is sufficient nitrogen in the tank is by measuring the gas pressure or the overpressure in relation to the outside air. If the pressure decreases, the nitrogen has to be topped up.
- Temperature measurement: As an extra safeguard, a temperature sensor is sometimes placed in the tank. Unwanted temperature changes indicate possible dangers.