In an automatic liquid nitrogen supply, LN2 is transported under pressure through vacuum lines from the bulk tank to the individual storage tanks. However, liquid nitrogen is not a trivial medium: even in the best vacuum-insulated line, it absorbs heat along the way. This heat causes some of the liquid nitrogen to evaporate, resulting in a two-phase mixture of liquid and gas.
This two-phase mixture is problematic for downstream devices and processes. Gas bubbles in the line can interfere with valves and sensors, reduce the flow rate and impair the accuracy of the level measurement. This is where the phase separator comes into play: a device that separates the gaseous and liquid phases and forwards only pure liquid nitrogen to the consumers.
Consarctic® integrates phase separators as an important part of its automatic supply systems. In this article, we explain the functionality and benefits of this often underestimated component.
A phase separator utilizes the physical difference in density between liquid and gaseous nitrogen:
The two-phase mixture is fed into a vessel in which it can settle. The heavier liquid nitrogen collects at the bottom, while the lighter nitrogen vapor rises and is discharged via a separate outlet. Pure liquid nitrogen is fed into the supply line from the bottom of the vessel.
The phase separator is typically operated at a defined pressure level. The separated vapor is discharged in a controlled manner without entering the supply line. This ensures a constant quality of the nitrogen supplied.
Many cryogenic devices are sensitive to gas bubbles in the nitrogen flow. Level sensors in particular, which are based on the principle of thermal conductivity, provide incorrect measured values if they are surrounded by gas instead of liquid. A phase separator prevents this source of error.
Gas bubbles in the pipe can interrupt the flow in batches (slug flow). This leads to uneven filling of the storage tanks and, in the worst case, can lead to flooding. The phase separator ensures a steady, even flow of liquid.
The separation of the vapor component ensures that only liquid nitrogen - with its full cooling potential - is delivered to the tank. The separated vapor can alternatively be used for less critical applications or discharged in a controlled manner.
Consarctic® strategically positions phase separators within the LN2 distribution network:
The correct dimensioning of a phase separator depends on several factors: the pipe length (and therefore the expected steam content), the flow volume and the operating pressure. Our engineers take all these parameters into account when planning your automatic supply.
A well-designed phase separator is a low-maintenance appliance. Regular inspection is limited to checking the seals, pressure gauges and blow-off valves. As part of Consarctic®'s regular maintenance contracts, the phase separator is checked as standard.
The phase separator is one of those components that works behind the scenes - but has a significant impact on the reliability and efficiency of a cryogenic supply system. As an integral part of the Consarctic® cryogenic systems, it ensures that your cryobank is always supplied with the best possible prepared nitrogen.
Are you planning an automatic LN2 supply or would you like to optimize your existing system? Contact our planning engineers for a technical consultation in which we optimally coordinate all components - including phase separation.