For over 10 years Nico SpA has been working in the tank cleaning sector using an innovative tank cleaning process called “NicoTank” for cleaning crude oil storage tanks through an automatic process suitable for cleaning all types of tanks (both fixed roof and floating roof tanks) and recover hydrocarbons. The tank cleaning process is based on the principle of mechanically liquefied hydrocarbon sediments by injecting crude oil or fuidifying agents into the closed tank through a jet washer (that is mounted in the transport pipes of the roof tank and on the bottom through the manholes) and using energy and heat during the process. In the first stage of the Nico Tank process, the sludge is dissolved with crude oil or other solvents and once the hydrocarbons are separated, they are ready for the refinery.
NicoTank is a closed circuit tank cleaning system, which is considered practical and safe and helps reduce to a minimum the entry of personnel within confined spaces. Once the work site is set up, nozzles are placed on the manholes of the tank. When and if the tank level is above the level of the manhole, the nozzles are installed with the use of special ‘HOT TAP MACHINE’. This system allows the installation of the nozzles on the manholes, while cold cutting them.
Next, gas, oil or other middle distillate can be used to dissolve and recover further hydrocarbons from the residues and from the sediment layer on the bottom of the tank. The sludge that dredges out from the tank is now ready to be treated in a “Centralized Sludge Treatment Facility”. The technology used by Nico S.p.a. includes the circulation and fluidification of the product and the use of a three-phase and two-phase centrifugation station that allows the recovery of hydrocarbons and reduces to a minimum the waste to be disposed of. Now the solid waste may be treated using a drying system called NICODRYER, which operates in a slightly depressurized closed circuit, with water and oil condensation.
In order to assess the recovery of valuable substances the composition of the sludge needs to be evaluated. Typical sludge is made up of 80% – 90% heavy Hydrocarbons and paraffin, 5-20% water and 3-5% non organic materials.
The configuration of the Centrifugation Plant with a “pre-teater”, decanter and vertical disc centrifuge allows the reach of high quality separated oil, water with low content of oil and solids and a minimum quantity of waste for the landfill.
When the product level is below the level of the manhole and it isn’t possible to continue with the circulation, the entire circuit is dismantled and the manholes are opened. In the case when some residues of sludge are still present, it is possible to use the NES-MOVER system, (later described in more detail), which allows the final cleaning phase to be carried out and requires only 1 technician to enter within the tank.
At the end of the process, a final washing of the walls, roof and tank floor is performed, in order to obtain a Gas Free environment within the equipment.
The NES-MOVER system comprises of several individual components:
- The MOVER
- The lobe pump
- Umbilical storage reels
- Diesel driven hydraulic power pack
The NES-MOVER system is a purpose built tank cleaning tool for large diameter above ground storage tanks; The NES-MOVER system is proven to be the fastest and most efficient way to carry out desludging operations; typical desludging rates of up to 200 m³ per day can be achieved with an experienced operator. The system is controlled by an operator on board car. Such system can be used alone or together to a previous cleaning phase through a closed circuit circulation system.
Thanks to a stern and continuous collaboration with the University of Catania – Department of Industrial Engineering – new trials related the activity of Tank cleaning have recently been developed. Taking advantage of the use of last generation technologies and equipment, the new NicoTank process has allowed us to reach the following objectives:
- Reduction of the time needed for the installation of the equipment
- Installation of the equipment with non-invasive and applicable methodologies also for tanks which are not in optimal conditions
- Reduction of the number of specialized technicians within the tank for the final reclamation operations
- Reduction of the total reclamation time
- Recovery of a high percentage (around 90%) of hydrocarbons present within the tank
- Reduction of the total quantity of waste to be taken to the waste pit
- Reduction of the total costs related to the operations of reclamation and waste disposal