Large Scale Yellow Grease Purification | A Centrifuge Case Study

Used Oil Self-Cleaning Centrifuge

Table of Contents

Synopsys

Dolphin Centrifuge designed and manufactured a complete Yellow Grease purification system featuring an Alfa Laval ‘Self-Cleaning’ Disc-Centrifuge. The system was supplied to a yellow-grease (UCO) collection company. The following is a case study of this particular application of a Yellow Grease centrifuge for large scale processing.

Case Study of Centrifuge on Yellow Grease Processing.

WVO Purification Alfa Laval Centrifuge

Customer Background

A large-scale, mid-west waste oil collection company processed 6M gallons per year. They collect waste oil consisting of grease trap waste, UCO, yellow grease, restaurant slop oil, fryer oil, etc.

The company used the age-old heating method and settling to get good oil from their collected yellow grease. In this process, the processor heats the yellow grease and allows it to settle under gravity. They then decant the clean oil off the top, leaving the ‘rag layer’ (emulsion), water, and sludge in the tank.

Processing Challenges

There are many challenges with this method of purifying yellow grease. Some of these are listed below.

  • Settling under gravity takes time – it is a slow process.
  • Settling also requires storage volume – more investment in tanks.
  • Heating large volumes of crude yellow grease are energy-intensive.
  • Decanting clean oil leaves a lot of ‘good’ oil in the tank bottom.
  • Cleaning tank bottoms are essential to reclaiming storage volume.
  • Disposal costs are associated with a large volume of tank bottom waste.

Centrifuge Selection and Validation Process

The yellow grease company contacted Dolphin Centrifuge in mid-2018. They wanted to investigate using an industrial centrifuge to improve their process efficiency.

The customer provided a detailed process flow diagram (PFD) to Dolphin Centrifuge. The PFD provided details on their existing facility, equipment, and process.

Customer Sample Testing

Dolphin Centrifuge has extensive experience with WVO processing. Based on our experience, we suggested pilot-scale centrifuge testing the customer’s WVO sample.

As part of this process, we run a small sample of the process fluid through our small-scale disc stack centrifuge. This is a 3-phase centrifuge capable of separating water, oil, and sludge.

If confirmed by pilot-scale testing, phase separation assures the customer of disc stack centrifuges’ applicability for their process.

Yellow Grease Sample Testing Results

The test results showed excellent separation at an optimum process temperature of 180F. The test simulated a flow-rate of about 40 GPM. This was the customer’s preferred throughput rate in production.

The customer compared the clean oil from the test centrifuge with their product. The disc-stack centrifuge produced a much better product. The centrifuged clean oil had no sludge and < 0.05% water!

Based on the test results, Dolphin offered a detailed technical proposal for a centrifuge system. Dolphin also provided an improved PFD for the customer’s existing plant. The intent was to repurpose some of the existing pre-straining equipment.

The quality of the purified yellow grease and centrifuge related cost savings convinced the customer to order the centrifuge system.

Installation, Startup, and Benefits of the Centrifuge System

Dolphin Centrifuge designed and manufactured a complete, turn-key centrifuge system. It has the capacity to process 30,000 gallons of yellow grease per day. The customer installed the centrifuge system at their facility under our guidance. After installation, Dolphin engineers helped startup the centrifuge system at the customer’s site.

Labor (decanting, changing filters, etc.) and material cost savings (filter media, etc.) were soon realized. The customer was able to recoup the capital investment in less than 6 months of installation! The ~30% increased throughput was an extra benefit. Their annual throughput was on track to reach 8M gallons.

The centrifuge also eliminated some of the settling tanks.

Yellow Grease Centrifuge Technical Details

The featured image (on top) shows the centrifuge supplied for yellow grease processing at 40 GPM.

Listed below are the components and accessories of this centrifuge system.

Centrifuge Capabilities

The centrifuge can 3-Phase separation of yellow grease to remove all free-water and sediment down to 0.5µ. The system can process up to 40 GPM of yellow grease at 180 F to separate all free water and sludge.

Conclusion

In summary, an industrial centrifuge is an ideal solution for the purification of yellow grease. As detailed above, it is cost-efficient for large scale purification of yellow grease.

Contact Dolphin Centrifuge for more information or to discuss your particular application with our centrifuge experts!