Location: Local Sarnia, Ontario Storage Tank Facility
Tank Capacity: 150 ft. in diameter and 48 ft. in height
Roof Type: External Floating Roof (EFR)
Sludge Content: 353,145 ft3 / 10,000 m3
Sludge Recovery Rate: Close to 98%; 346,082 ft3 / 9,800 m3
Local Sarnia Storage Tank Facility: Allerion Oilfield Services utilized the combined DS Jet Mixing System with Oreco’s Non-Man Entry Automated Tank Cleaning System. The main objectives to be accomplished with this project were to achieve reduced manhours spent inside the tank, reduced tank outage time and minimum waste generation thereby reducing overall cost to the customer.
For more than 20 years, the DS Jet Mixing System, developed by Allerion Oilfield Services, has been the best method for recovering aboveground crude oil storage tank sludge. This technique, developed as an alternative to conventional prop mixers, is safe, efficient, and cost-effective in combating sludge build-up.
To clean this tank, we started desludging using the DS Jet Mixing System. We typically empty the tank with vacuum trucks after Jet Mixing to prepare for personnel entry and manual cleaning. We utilized Oreco’s Non-Man Entry Automated Tank Cleaning System, which provided remarkable results in terms of personnel and environmental safety.
In this technique, Nitrogen is first introduced to make the tank atmosphere inert and avoid risk of ignition or explosion. The target is to maintain the oxygen level at or below 8% throughout the process and is verified by continuous gas monitoring. Next, heated cutter liquid washing begins. The heated cutter liquid is re-circulated using Single Nozzle Sweepers (SNS®) and Automated Tank Cleaning Technology. These nozzles produce low pressure, high impact jets of recirculated fluid which efficiently cleans all internal surfaces of the tank in a precise computer-controlled pattern, with lower water usage.
Following the cutter liquid wash, a hot water and chemical wash (EverSolv) is performed to remove the residual hydrocarbons and lower the volatile and toxic compounds in the tank atmosphere. In this case, the hot water and chemical wash was repeated to achieve the desired results leading to significant hydrocarbon recovery.
Finally, the manways were opened to vent the tank to the atmosphere and raise the oxygen level to the desired level. Upon testing, the LELs and Benzene levels were zero and the tank was ready for personnel entry without the use of supplied air making it a huge success.