Automated Solvent Recovery for High-Purity Laboratory Analysis

Customer: OELCHECK GmbH
Industry: Chemistry / Analytical Testing / Lubricant Analysis
Application: Purification and recovery of kerosene and heptane for reuse in analytical laboratories

Background:
OELCHECK GmbH is one of Europe's leading laboratories for lubricant and operating fluid analysis, offering more than 100 analytical methods for industries ranging from automotive and energy to heavy machinery. In routine laboratory operations, large volumes of organic solvents are required for cleaning, rinsing, and sample preparation. In particular, heptane is used for rinsing and cleaning procedures, while kerosene is used as a dilution solvent for highly precise ICP-OES trace element measurements.

Traditionally, these used solvents were collected and disposed of as hazardous waste in IBC containers. However, increasing disposal costs, sustainability goals, and the demand for resource efficiency motivated OELCHECK to establish a closed-loop solvent recovery process while maintaining the extremely high purity standards required for trace analysis.

Challenge:
The company faced several technical and operational challenges when implementing solvent recycling:

• Recovering used solvents at analytical-grade purity, especially kerosene used for trace element analysis.
• Ensuring that critical contaminants such as sulfur and phosphorus remained below detection limits to avoid interference with ICP-OES measurements.
• Handling large solvent volumes with minimal operator involvement.
• Managing a complex plant layout: solvent waste is collected in the basement and must be pumped approximately 3 meters vertically over a 25-meter pipeline to the evaporation systems.
• Continuously collecting the purified distillate in 200-liter drums outside the building without interrupting the process.

Solution:
To address these challenges, OELCHECK implemented two independent solvent recovery systems, each based on a Hei-VAP Industrial rotary evaporator equipped with Hei-VOLUME Distimatic Pro control and a Hei-CHILL 5000 recirculating chiller. The chiller was deliberately installed outside the laboratory to prevent heat emissions within the analytical workspace.

System configuration:

• Heptane recovery: 160 mbar, 90 °C
• Kerosene recovery: 45 mbar, 115 °C

A key advantage of the Hei-VAP Industrial systems is their semi-continuous operation:

• Vacuum remains stable throughout the entire process.
• Fresh solvent waste is fed into the evaporator while distillation is ongoing.
• Kerosene recovery runs continuously throughout the day.
• For heptane, the residue flask only needs to be emptied automatically once or twice a day for a few minutes.

Unlike conventional batch systems, which require interruptions every 10–20 minutes for refilling, the semi-continuous process enables near-uninterrupted distillation with consistent quality and significantly higher throughput.

The process is highly automated: the systems are started in the morning, solvent waste is automatically pumped from the basement to the evaporators, and purified solvent is continuously transferred under pressure over a distance of more than five meters into external storage drums. Even drum exchange can be carried out during operation without interrupting the process.

Results and Performance:

The implementation of the Hei-VAP Industrial systems delivered outstanding technical, economic, and environmental benefits:

Technical performance

• Throughput:
  • Approximately 5 L/h of kerosene
  • Approximately 7 L/h of heptane
• Purity:
  • All critical elements, including sulfur and phosphorus, remain below the detection limit.
• Recovery rates:
  • 80 - 90% for kerosene and heptane
  • Overall laboratory solvent recovery of approximately 55%, considering additional solvents that are not recycled.

Economic benefits

• Annual savings of approximately:
  • 65,000 liters of kerosene
  • 18,000 liters of heptane

Environmental benefits

• Annual CO₂ savings through avoided production of fresh solvents:
  • Heptane: ~32 tonnes CO₂
  • Kerosene: ~12 tonnes CO₂
  • Total: approximately 44 tonnes CO₂ per year
• Reduction of hazardous solvent waste by more than 24,000 liters annually, corresponding to approximately 60 fewer IBC containers (400 liters each).
• Elimination of 45 – 55 transport operations per year due to reduced hazardous waste disposal and fresh solvent deliveries.

Conclusion:
With the implementation of Hei-VAP Industrial systems combined with Hei-VOLUME Distimatic Pro, OELCHECK has established an economically attractive and environmentally sustainable solvent recycling process. The fully automated, semi-continuous operation minimizes operator involvement while delivering distillates of the highest analytical quality.

Particularly noteworthy is the exceptional purity of the recovered kerosene, which can be reused directly for demanding ICP-OES trace element analysis without causing matrix effects or instrument contamination. By reducing hazardous waste, lowering CO₂ emissions by nearly 44 tonnes per year, and significantly decreasing solvent consumption, OELCHECK demonstrates how modern evaporation technology can contribute to both operational excellence and sustainable laboratory practices.

Customer feedback:
"The Hei-VAP Industrial systems run fully automatically with minimal supervision—exactly what we needed. We are particularly impressed by the high purity of the recovered kerosene, which can be safely used in ICP-OES trace analysis. The annual savings of more than 24,000 liters of solvent and almost 44 tonnes of CO₂ speak for themselves. The semi-continuous process enables a significantly higher throughput than traditional batch systems. If any questions do arise, Heidolph is very easy to reach and provides prompt assistance."

Heidolph product models used:

hei-vap industrial

hei-volume distimatic pro