Costs – Benefits Analysis

The value of the recovered hydrocarbon obtained by Nuova Saimar S.R.S.® cleaning activity can reach the 98% of the hydrocarbon contained in the sludge. It is dissolved in the  fluidizing oil and carried to the production, thus becoming a real recovery. Manual Cleaning technique, on the other side, allows no hydrocarbon recovery, as sludge is just transferred and stored to the receiving tank, and is not sent back to the production line. Manual cleaning, therefore, generates further costs at the time when the receiving tank shall be cleaned.

1.  S.R.S.® operations are carried out with no people entering the tank until the final cleaning of the sediments. In this last stage, considering that the water‐washing phase has eliminated HC e H2S from the tank internal atmosphere, people may enter without any breathing device. As a precaution, before people enter the tank, the tank’s internal atmosphere is checked for oxygen and hydrocarbons content. Conversely, during manual operations people are compelled to work in a flammable and hazardous environment. In addition, a big quantity of hydrocarbons dissolves in the atmosphere thought the opened man‐holes, due to the superfluous steam used during manual operations.
2. Sometimes the amount of sludge is too high for the roof to land (more than 2m). Even in this case the S.R.S.® guarantees a safe roof landing. The operations start with the roof floating on the liquid phase, and the S.R.S.® unit operates by reducing sludge peaks that prevent the roof from landing. This result can be achieved with any kind of sludge shape and quantity.
   The Jet Washers are installed on the roof using the roof support legs. To avoid to compromise roof stability, and to guarantee suitable roof support, a max of 20% of the legs are used. Supports are then put back into place before people enter the tank for final cleaning.
3. During the S.R.S.® washing phase, the atmosphere within the tank is kept monitored, to avoid it becomes flammable, and nitrogen is used to inert it. During this phase the unit is equipped with O2 monitoring system and alarm. Safety instruments are brand new and subject to maintenance control procedures. Very experienced and highly qualified people manage and supervise every operation.

• During the fluidization phase, to avoid any HC loss, all the openings that may connect the tank’s inner atmosphere to the external atmosphere are purposely sealed
• No chemicals are used during S.R.S.® operations.

When asphaltenes and paraffin melt, they get more compact when back to room temperature, therefore a higher temperature is required to melt them a second time. To avoid this and leave the solution stable for a very long time, the S.R.S.® carries out a continuous soft heating.

The S.R.S.® enable to recover up to the 98% of the hydrocarbon contained in the sludge; the recovered hydrocarbon is returned then to the client, together with the fresh oil used to fluidize it.
The subsequent hot‐water washing leaves a residue inside the tank that shall be disposed, which average composition is 1/3 inert, 1/3 water, 1/3 solid hydrocarbon. No other system gives a better recovery, and a minor quantities of waste material.
Such result generates a significant cost saving that gets evident only by taking into consideration the entire cleaning project.

The S.R.S.® enable to recover up to the 98% of the hydrocarbon contained in the sludge; the recovered hydrocarbon is returned then to the client, together with the fresh oil used to fluidize it.
The subsequent hot‐water washing leaves a residue inside the tank that shall be disposed, which average composition is 1/3 inert, 1/3 water, 1/3 solid hydrocarbon. No other system gives a better recovery, and a minor quantities of waste material.
Such result generates a significant cost saving that gets evident only by taking into consideration the entire cleaning project.

S.R.S.® operations are much faster than any other type of manual cleaning.
During the washing phase the sludge is treated at a speed of approx. 120-130 m3/day (it depends on the technique used and on the type of sludge). At the end of S.R.S.® washing, the residue that shall be taken out, manually or  mechanically, ranges between 5 and 10% of the original sludge quantity.
The hot water washing phase facilitates the final manual cleaning operations.

At a first glance, S.R.S.® operation may appear more expensive than manual cleaning method.
The S.R.S.® is cheaper, if all the benefits are considered:

• the value of a 100% safe method, which value is for the current European  regulations “inestimable”;
• the recovery of valuable material
• the subsequent saving of treatment/disposal cost of that material that has been recovered.