The transportable Sludge Recovery System (SRS) allows the delivery of hot or cold crude oil or water, under pressure to the Jet washer nozzles system installed on the roof of a tank. Based on the proven Crude oil washing technology the cleaning process, performed as a closed loop operation or with fresh oil provides safe and effective cleaning. Safety features ensure hydrocarbon vapour emissions are minimised and the atmosphere in a tank maintained in a safe condition.
Crude oil washing is the most effective method of cleaning floating roof tanks with large volumes of sludge. Unlike side cannons, the diameter of a tank does not affect the effectiveness. The ability to install cleaning nozzles across the diameter of the tank ensures maximum coverage, improving dissolution of sludge deposits wherever they are located.
Crude oil washing allows dissolution of sludge deposits prior to landing of a floating roof thus reducing the possibility of damage during the roof landing process.
Using a suitable crane the riser once constructed at ground level undergoes installation. Constructed of high quality flanged pipes to ensure rigidity and the strength required, the riser provides oil or water to the jet washers on the roof from the SRS at a pressure of 6 – 8 bar.
UNIT B (DELIVERY UNIT)
Consisting of a 180 M³/Hr sludge pump, Steam driven heat exchanger and a compressed air reservoir. The delivery unit is used to provide clean oil or water (heated when necessary) via the riser to the Jet washers for cleaning of the tank. The compressed air reservoir provides a regulated airflow for the drive units of the Jet washers, pneumatic valves and safety valves on the SRS units.
UNIT A (RECOVERY UNIT)
Consisting of a 180 M³/Hr sludge pump and an ejector tank header system and pump, and scrubber tank. The recovery system’s primary use is to collect oil / sludge mixtures from the tank during cleaning for transfer within the terminal or recycling to the jet washers for further cleaning. The recovery system when used during hot water washing recovers oily water mixtures for discharge to the separator. The scrubber tank supplies the water ring vacuum pump and cleans recovered hydrocarbon gases before return to the tank.
Based on a simple weir principle recovered oily water mixes transferred from Block A to the separator. After natural separation, the clean water feeds block B for further cleaning of the tank with recovered oil discharged to the terminal.
NITROGEN SUPPLY HOSE
After the floating roof landed, or in the case of a fixed roof tank from the very start, it is necessary to maintain an inert atmosphere inside the tank to avoid static electricity build up and risk of explosion. Use of Nitrogen gas from either a liquid nitrogen tank via an evaporator unit or nitrogen generator to the void space ensures a safe atmosphere for the operation. An oxygen sampling system monitors the atmosphere continuously throughout the operation taking readings at multiple points in the tank.
Constructed of stainless steel, aluminium alloy and bronze, the Jet washer design allows insertion through existing roof supports with a minimum diameter of 75mm. Driven by an integrated air motor the system provides rotation in horizontal and vertical planes, being programmable for roof, floor or all-round cleaning modes. The internal nozzle diameter of 30mm combined with an anticipated throughput of up to 90 M³/hr at a pressure of seven bar provides cleaning without risk of damage to tank coatings.
FLOATING ROOF LEGS
During installation of equipment, based on cleaning pattern and roof stability floating roof legs in locations and number predetermined and agreed with the terminal are removed for installation of the Jet washer units. The legs are cleaned, wrapped in plastic and laid as close as possible to their location. This maintains the cleanliness of the roof and ensures replacement of removed legs in their correct location at the end of cleaning.
DOUBLE VALVE SYSTEM
Supply to the jet washers is via the riser to the temporary pipeline system installed on the roof. A double valve system between the temporary pipeline and the Jet washers provides increased isolation. A gate valve for operation of the jet washers, supplemented with a pneumatically controlled valve which allows remote operation during the hours of darkness or when gas levels do not permit personnel to access the roof area. This provides additional safety and reduces manned access to potentially dangerous areas.