Technology
Batch Used-Oil Re-Refining Plants
Dedicated dehydration, degassing and high-vacuum distillation — proven up to 120 TPD and beyond.
Overview
Balaji Consultants designs and supplies complete batch used-oil re-refining plants incorporating feed preparation, dedicated dehydration and degassing, high-vacuum distillation, base-oil recovery and suitable downstream finishing systems. Unlike conventional single-vessel batch systems, the Balaji process utilises a dedicated dehydration and degassing vessel followed by a separate high-vacuum distillation vessel. Separating these operations provides improved process control, protects the high-vacuum section from excessive water and volatile contaminants, improves vacuum stability and enhances overall plant reliability.
Batch re-refining remains one of the most practical and proven technologies for processing used lubricating oils. It offers exceptional flexibility in handling variable feedstocks, allows operators to optimise processing conditions for each batch, and enables the production of different base-oil grades according to market requirements. The technology is particularly suitable where feedstock quality varies significantly, where different product grades are produced in campaigns, or where operational flexibility is an important consideration.
Over the years, Balaji Consultants has successfully designed and supplied batch re-refining plants with capacities up to 120 TPD and beyond, demonstrating that well-engineered batch technology can be successfully applied to large commercial production facilities while maintaining product quality, operational reliability and process flexibility. Although continuous plants may offer advantages for certain applications, batch re-refining continues to provide an economical, dependable and technically robust solution for many projects, particularly where feed variability, product flexibility and phased capacity expansion are important considerations.
How It Works
1
Feed Preparation & Charging
A measured quantity of used lubricating oil is transferred into the dehydration and degassing vessel. Depending on the quality of the incoming feed, preliminary settling, coarse filtration or other feed preparation may be carried out to remove free water, sludge and large suspended contaminants before charging. Feed quantity and available laboratory analysis are reviewed to determine the appropriate operating conditions for the batch.
2
Dehydration & Degassing
The feed is heated in the dedicated dehydration and degassing vessel under controlled vacuum conditions. During this stage the process removes free water, dissolved water, entrained gases, low-boiling volatile hydrocarbons and other volatile contaminants; the resulting vapours are condensed and collected separately. Effective dehydration and degassing are essential to ensure stable operation during the subsequent high-vacuum distillation stage, minimise foaming and protect the vacuum system from excessive vapour loading. Once the feed has reached the required condition it is transferred to the high-vacuum distillation vessel.
3
Light Hydrocarbon Recovery
Inside the high-vacuum distillation vessel, vacuum is progressively increased while the feed temperature is carefully raised. The lighter hydrocarbon fractions — which may include petrol-range, kerosene-range and diesel-range hydrocarbons depending on the feedstock — are recovered first and collected separately. Removing these components before recovering the base-oil fractions improves product flash point, reduces vapour loading on the vacuum system and provides better control over the subsequent distillation process.
4
High-Vacuum Base Oil Distillation
Following removal of the lighter fractions, the distillation vessel operates under deep vacuum while temperature is gradually increased to recover the lubricating-oil fractions. Operating under high vacuum significantly reduces the boiling temperature of the oil, allowing valuable base-oil components to be recovered while minimising thermal degradation. Depending on project requirements, the recovered distillate may be collected as a single combined base-oil fraction or as multiple viscosity-grade base-oil cuts; the operator controls cut transitions using process temperature, vacuum conditions, distillate characteristics and the required finished-product specifications.
5
Residue Recovery & Discharge
As distillation progresses, the non-volatile components become concentrated within the distillation vessel. Once the desired base-oil recovery has been achieved, or when further recovery is no longer technically or commercially justified, heating is discontinued and the batch is completed. The remaining residue — comprising heavy degraded hydrocarbons, carbonaceous material, asphaltenic compounds, additive-derived contaminants, metals, ash and other non-distillable components — is discharged to the appropriate storage or downstream handling system. Residue quantity and characteristics are recorded as part of routine operating data to provide valuable information regarding feedstock quality and overall plant performance.
Key Equipment
Feed preparation and pre-treatment system
Dedicated dehydration and degassing vessel
Separate high-vacuum distillation vessel
Thermic fluid heating system with heat-transfer coils or Reboilers
Multi-stage condenser train (dehydration, light-ends and base-oil condensers)
Product receivers with level gauges and sampling points
High-vacuum pump package
Residue discharge pump or gravity drain system
Process controls and automation (PLC or manual)
Process Configurations
A
Two-Vessel System (Balaji Standard)
A dedicated dehydration and degassing vessel is followed by a separate high-vacuum distillation vessel. Separating these operations provides improved process control, protects the high-vacuum system from excessive water and volatile contaminants, improves vacuum stability and enhances overall plant reliability.
B
Single-Vessel Atmospheric + Vacuum Still
The conventional configuration where dehydration and high-vacuum distillation are carried out sequentially in a single vessel. Simpler in terms of equipment count, though it provides less protection to the vacuum system and affords less independent control over each processing stage.
C
Multi-Vessel Campaign System
Two or more batch stills operated in staggered cycles — while one vessel is being charged and heated, another is in the main cut recovery phase and a third is discharging residue. Smooth feed throughput reduces peak energy demand and increases effective daily processing capacity without the capital cost of continuous equipment.
Selection Considerations
Selecting the appropriate batch re-refining configuration depends on several project-specific parameters, including feedstock composition, required product quality, plant capacity, available utilities and the desired operating philosophy.
Feedstock variability is an especially important consideration. Where incoming used oil can vary substantially in water content, light hydrocarbons, additives, metals and other contaminants, independent dehydration and degassing provides greater operational control before the high-vacuum stage.
For projects requiring multiple base-oil grades, batch operation allows the distillation conditions and cut points to be adjusted from one campaign to another. This makes the technology particularly useful for operators serving different markets or gradually expanding production capacity.
Frequently Asked Questions
Batch re-refining is particularly suitable when feedstock quality varies significantly, when different base-oil grades need to be produced in campaigns, or when phased capacity expansion and operational flexibility are important. It also offers a practical solution where product flexibility is more important than maximum continuous throughput.
Batch re-refining can be engineered for a wide range of capacities. Balaji Consultants has successfully designed and supplied plants up to approximately 120 TPD and beyond, depending on the required configuration, number of vessels, feedstock characteristics and operating philosophy.
The Balaji standard configuration uses a dedicated dehydration and degassing vessel followed by a separate high-vacuum distillation vessel. This separation improves process control, reduces water and volatile loading on the vacuum system, improves vacuum stability and provides greater operational reliability.
Related Technologies
Not sure which process configuration is appropriate?
Process selection depends on feedstock composition, required product quality, capacity, utilities, operating philosophy and project economics. Share your available feedstock data with our engineering team for an initial technical evaluation.
Submit Feedstock InformationDiscuss Your Project
Connect with our engineering team to review your feedstock, required capacity, and process objectives.