Large ships generate significant amounts of waste oil through operations like contaminated fuel, bilge water management, and used engine lubrication. Efficiently recovering and processing this waste oil is essential for environmental compliance and cost management.
Traditional methods, such as heating and settling, are energy-intensive and inefficient. This case study examines how a waste oil processor in Guam improved its recovery process by implementing the DMPX-028, a disc stack centrifuge from Dolphin Centrifuge, capable of handling 4,800,000 gallons of waste oil annually.
The facility's traditional filtration machine used heating waste oil to reduce its viscosity. This process consumed a significant amount of energy, increasing operational costs.
The heating and settling method was ineffective in removing fine particulates and water mixed with the oil, leading to lower purity levels in the recovered oil.
Settling tanks required frequent maintenance to remove sludge, resulting in increased operational costs and downtime. Additionally, the centrifugal filter used in the traditional system was inefficient in handling the contaminants present.
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To find a more efficient solution, the facility partnered with Dolphin Centrifuge, an established manufacturer of waste oil centrifuges. Dolphin Centrifuge recommended installing the DMPX-028 disc stack, a self-cleaning centrifuge. This is a purpose-modified Alfa Laval centrifuge for high-efficiency waste oil processing.
Each DMPX-028 unit processes up to 20 gallons per minute (GPM) at 180°F. By deploying one unit operating continuously for 16 hours a day over 250 days a year, a total processing capacity of 4,800,000 gallons annually was achieved.
DMPX-028 Self-Cleaning Disc Stack Centrifuge Specifications | |
Capacity | 30 GPM light viscoisty oils; 20 GPM on waste oil |
Bowl Speed | 8,000 RPM |
Drive Motor | 10 HP |
Module Size/Weight | 5' x 6' x 6' (H) ; 3,200 Lbs |
Services Needed | 480 V 3-Phase Power, Potable Water, Compressed Air |
The centrifuge effectively separates waste oil from contaminants, including fine particulates, water, residual fuel, and emulsions known as the 'rag layer'. This separation increased the recovery rate by approximately 20%, enhancing both efficiency and profitability.
A pilot test confirmed that the DMPX-028 centrifuge achieved high-quality recovered oil, which is sold to re-refiners and used as heating fuel, improving the overall waste management process. The centrifuge serves as a reliable waste oil purifier, ensuring cleaner output.
Waste oil is introduced into the centrifuge through a central inlet tube or pipe.
The centrifuge’s bowl spins at high speeds, generating centrifugal forces up to 9,000 Gs. This force is essential for separating oil from lighter contaminants like water, residual fuel, and fine particulates.
Inside the bowl, a series of conical discs are closely packed. These discs significantly increase the surface area available for separation. As the waste oil flows through the gaps between the discs, the centrifugal force drives denser contaminants outward while allowing the cleaner oil to remain closer to the center.
Contaminants accumulate at the periphery of the bowl, forming a concentrated sludge that is automatically ejected without slowing down. Additionally, the centrifuge effectively separates the 'rag layer' or emulsions, further purifying the oil.
The purified oil flows towards the center and exits the centrifuge through an outlet for sale to re-refiners or use as heating fuel.
The centrifuge automatically ejects the separated sludge while maintaining its operating speed. This feature ensures continuous operation with minimal manual intervention.
The high centrifugal forces and increased surface area provided by the disc stack enable the centrifuge to remove even the smallest contaminants, resulting in higher-purity oil.
The centrifuge's ability to separate or break emulsions or the 'rag layer' increases the overall recovery rate by approximately 20%, maximizing the amount of usable oil recovered from the waste stream.
Unlike the batch nature of heating and settling, the centrifuges operate continuously, allowing for a steady flow of recovered oil and reducing downtime.
By deploying multiple DMPX-028 centrifuges, the facility can easily scale operations to handle increased volumes of waste oil, ensuring consistent performance without bottlenecks.
The centrifuge system significantly lowers operational costs by reducing energy consumption associated with heating and minimizing the need for frequent maintenance of settling tanks. Additionally, the longevity of the centrifuges’ components reduces replacement costs.
The self-cleaning feature minimizes the need for manual sludge removal, freeing up labor resources for other critical tasks within the facility.
The centrifuges' compact design requires less floor space than multiple settling tanks, optimizing the facility’s layout and allowing for increased processing capacity within the same area.
A comparison of waste oil before and after processing with the DMPX-028 centrifuge is presented below:
Sediment | 0.42 | 0.06 | 473 | wt% |
Water (by distillation) | 38 | 1.2 | 95 | vol% |
Metals: | ||||
Vanadium | 28 | 31 | ppm | |
Aluminum | 495 | — | ppm | |
Silicon | 386 | — | ppm | |
Aluminum + Silicon | 881 | 222 | ppm | |
Ash Content | 1.17 | 0.09 | 482-00a | wt% |
Switching to the centrifuge system saved approximately $380,000 each year.
Lower energy use for heating decreased the carbon footprint.
Efficient separation reduced the volume of contaminated waste requiring disposal.
Mechanical separation reduced the need for chemical additives.
Installing the DMPX-028, a disc stack centrifuge from Dolphin Centrifuge, significantly improved the waste oil recovery process at the Guam-based facility.
The centrifuge enhanced oil purity, increased recovery rates by 20%, and reduced annual costs by $380,000. These improvements led to more efficient operations and substantial environmental benefits.
By adopting the DMPX-028 centrifuge, Dolphin Centrifuge enabled the waste oil processor in Guam to achieve greater sustainability, lower operational expenses, and optimized waste management. This implementation highlights the effectiveness of disc stack centrifuges in transforming waste oil recovery in the maritime industry.