Recover oil while reducing waste handling costs. Alfa Laval PureDry is an automated system that separates waste oil into three phases: cleaned oil, water and super-dry solids.
Automated and modular
- Processes continuously at flowrates of up to 300l/h
- Compact, modular system, install in any space
- Integrates with onboard systems
- Smart automation adapts process control to feed conditions
- No water consumption or additional waste generated
Substantial savings on waste oil handling
PureDry cuts the cost of waste oil and sludge handling by removing water from the waste oil and concentrating the solids to super-dry sludge (typically 15-25 kg/24 h), thus eliminating oily waste and related disposal costs.
The efficiency of the system in terms of drying up oily waste streams means holding tank volumes for waste oil and waste water can be reduced, thus freeing up valuable space on board a ship or in a power plant.
Furthermore, waste fuel recovery is possible when fuel oil sludge are separated from lube oil sludge (separate sludge tanks) – fuel saving typically up to 0,4 % is possible.
The uniquely simple separator design ensures easy, reliable operation. The system separates the waste oil into three phases: cleaned oil, super-dry solids which can be disposed of as dry waste, and water clean enough to be sent to the bilge system. Smart automation adapts the process control to varying feed conditions. There is no water consumption and no additional waste generated.
Compact modular design
The compact PureDry system comprises a pumping module with emulsifier dosing unit, a heating module, a separation module and a control unit. Its modular design provides flexibility for installation in any convenient location and makes it easy to integrate with existing onboard systems.
Integrated waste oil/bilge water treatment concept
In combination with Alfa Laval’s PureBilge system, PureDry forms a complete, integrated sludge/bilge water treatment solution that can dry up all oily waste streams on the ship or in the power plant. PureDry separates out the oil, concentrates the solids to super-dry sludge which can be landed as dry waste, and sends the water to the bilge system. PureBilge then takes care of the fine polishing of the oily water prior to discharge overboard.
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How it works
The PureDry oily waste treatment system continuously processes sludge, separating oil, water and solids. It is comprised of a pumping module with dosing unit, a heating module, a separator module, and a control unit.
The separator bowl containing a disc stack rotates at high speed and solids from the waste oil feed accumulate at the periphery. From the periphery, the solids are continuously discharged by a patented spiral-shaped device called the XCavator into a container under the separator. The amount of solids accumulated in the container is continuously monitored by means of a load cell.
An oil paring disc, which forms part of the separator bowl, continuously discharges recovered oil from the separator through the oil outlet under pressure. The oil is directed to the oil recovery holding tank. A built-in water paring disc continuously discharges separated water through the water outlet. Although sealing water is added to the bowl during start-up, no more water needs to be added, thus no additional waste is created by the process itself.
Process operating principle
The system operates at flow rates of up to 500 liters(typically 150 to 200 liters) per hour. A positive displacement feed pump operating at a constant ﬂow directs the waste oil to the system. The process liquid then passes through a duplex strainer, which traps large particles, into a preheater. For optimum separation efficiency, the heater raises the temperature of the unprocessed liquid to the desired feed temperature of 95°C.
A three-way changeover valve directs the waste oil to the separation stage if all process conditions, such as feed temperature and feed pressure are met. During an alarm situation, loss of operating pressure, power failure or when any preset condition is not met, the valve recirculates the ﬂuid back to the waste oil tank.
The water is then transferred either to the bilge water treatment system for further processing to ensure that it meets IMO standards for discharge overboard, or back to the waste oil tank, according to the process conditions.
To enhance performance in the presence of stable emulsions, a demulsifier dosing unit is included. The unit is connected before the pumping stage in order to mix Alfa Laval demulsifier directly into the feed.
The process is continuously monitored and controlled by the EPC 60 control system for fully automatic operation.