FAQ – NESS NLPA150 / NLPA250

Passive light ends removal system NLPA150 / NLPA250 as special solution

In this FAQ-area, you can read some general questions and answers around the NLPA150 / NLPA250 of the NESS Light Ends Removal systems, which advantage you can take of it, and what you generally should consider for integration. In addition, it has to do with the infrastructure that should be given for successful operation.

What does the NESS Light-ends removal system do?

The NESS Light-ends removal system is a product in the NESSessities concept which constantly increases safety, availability, durability and efficiency in thermal oil systems. One of the 3 most important factors for a good quality is a stable flashpoint. The NESS Light-ends removal system helps you ensuring this permanently.

Besides acid figure and Conradson value,
the flashpoint is an important factor for good quality

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How do I integrate the NESS Light-ends removal system in my plant?

No problem at all! Like all NESSessities, also the NESS Light-ends removal system is designed as an individual module. Existing processes are not influenced. because the light-ends removal takes place in the bypass flow. This concept allows the relatively easy retrofitting also for already existing systems.

NESSessities work independently
in the bypass flow of the system

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Are there different light-ends removal systems available? And if yes, do we have to consider something?

Basically, there are two types of systems for light ends removal at NESS: a passive system and an active system.

The passive light ends removal system works with gravity. That means that it must be installed at least 2m above the highest point of the system (mostly the expansion tank). This often requires an additional steel structure which would preferably seem the thing to do when a new plant is planned and not for retrofitting. The solution is feasible for systems with up to 110,000 litres of thermal oil.

The active light ends removal system is very flexible because it is equipped with its own pump pump and a frequency converter. Therefore, among others, its implementation in existing systems can be planned better and it can also be used optimally for systems with more than 110,000 litres of thermal oil.

What product solutions are available for your system you will read here


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Do I need additional infrastructure for the operation of the light-ends removal system?

Besides a certain inlet pressure of the thermal oil, nitrogen, cooling water and control air will be required in addition. Due to its own pump and control unit, the active light ends removal system certainly needs the respective power supply.

Please find more details here.


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For operation, additional nitrogen and cooling water are required. What do I have to consider and how high is consumption?

Nitrogen is always required for the operation of the light-ends removal system. This is required for the intertisation and the generation of overpressure within the system. Consumption depends on the quantity of light-ends in the oil.

Nitrogen cylinder (50 litres / 200 bar)
With fresh oilapprox. 6 days
With used oilapprox. 2 days

To ensure the continuous provision of nitrogen and simultaneously to reduce the running costs, we recommend using a nitrogen generator with a 750-l nitrogen tank.

Cooling water is always required for the operation of the light ends removal systems. While the passive light ends removal systems mostly work without cooling water (due to air cooling), it is highly recommended for active light ends removal systems. In warmer regions with ambient temperatures of more than 25ºC it is even always required. Water cools the condenser in which the hot, gaseous light ends are cooled down and condensed.

Volume flow of cooling water200 litres / hour

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The recommended inlet temperature in the NESS Light-ends removal systems is 250 °C. What happens, if this is below that?

If the recommended inlet temperature is below 250 °C, removal of the light ends is still possible, but it will be clearly worse than at the recommended temperature.


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Is humidity removed from the thermal oil in addition to the light-ends?

Indeed, also water is removed from the thermal oil additionally to the light-ends. The evaporation temperature of water is approx. 100 °C and therefore, it is separated like the light-ends.


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What happens with the separated light-ends and what do we have to observe?

The separated light ends are collected in the light-ends collecting tank. This contains a volume of 70 litres.

It must be disposed of in accordance with the local regulations. We recommend storing in a metal tank outside the building in an explosion-proof room. The metal tank must always be kept closed and emptied by a company specialised in disposal.


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What do I have to consider in the place of installation of the NLPA150 / NLPA250? Which conditions must be met?

Generally, the light ends removal system must be installed at least 2m above the highest point (expansion tank) to operate it using gravity. The nitrogen for the light ends removal system flows through a nitrogen anti-cavitation valve from the expansion tank.
Because the passive light-ends removal works without its own pump, the return flow and the flow of the distillation tank must be connected on the intake and outlet side of the primary circulation pump (in the return flow of the heat transfer oil heater).

It should be connected to the flow line of the thermal oil system. The flow and return flow with the primary circulation pump between them.
With this, pay special attention to the following interface parameters:

Connection valves – thermal oil (inlet)Nominal diameter DN25
Connection valves – thermal oil (outlet)Nominal diameter DN50 (NLPA150) / DN80 (NLPA250)
Cooling water valvesNominal diameter 3/4´´ (NLPW250)
Thermal oil – flowmin. 1 bar + static height of the expansion tank +
overpressure due to nitrogen blanketing
Thermal oil – return flow–
Recommended inlet temperature 250 °C
Nitrogen supplyVia expansion tank
Air-cooled (NLPA150 / NLPA250)15 – 30 °C
Cooling water (NLPW250)2 – 4 bar

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How does the cooling of the condenser work for the NLPA? Are there any differences?

In case of the passive light ends removal with the NLPA150 / NLPA250, the condenser is cooled by an air-cooling system. Because it is installed on the building roof, the ambient temperature, which usually is between 15 °C and 30 °C, cools down the condenser of the light ends removal system.

Beside the air-cooled variant, the NLPA250 unit is also available as water-cooled variant (NLPW250), which makes it possible to use the system up to an oil volume of 110,000 litres. However, this solution is preferably applicable for smaller systems.


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Does a passive light-ends removal system pay off as retrofitting or better not?

Generally, the integration of a light ends removal system in a thermal oil system is always an advantage. Due to the relatively simple, technical design (no additional pump, no additional control unit), pure original cost is lower. However, the fine adjustment of the system and the additional steel structure for the installation must be considered for the total cost estimate as well.

Due to its flexibility in integration and installation, an active light ends removal system is therefore optimally suitable for retrofitting. Because it has an integrated pump and its control system, its integration in existing system can be realized more efficiently.


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Other FAQ topics that might interest you

Light ends in the heat transfer oil
What do the light ends cause in the heat transfer oil
and how to act best?

NESS NALD250 / NALD250i
Active light ends removal system NALD250 / NALD250i
for fast and flexible integration