vendredi 27 décembre 2013

How To Do Crude Oil Storage Tank Cleaning

By Harriett Crosby


Crude Oil Storage Tank Cleaning has been a challenging and daunting task for years. To simplify the processes used, we have broken down the three common methods below. Ti is a very involving process that includes the removal of sludge at the bottom of the storage chamber, treating the sludge to separate it and lastly is washing the receptacle. Some companies still use the conventional methods while some have advanced to the new developed methods for efficiency and time saving.

Starting with the conventional method, the sludge is manually removed from the tank bottom. It may take about 100 days depending on the number of personnel working on it and the machines being used. With more operators it can even take 2 months. At times tank cleaning machines that are remotely operated are used; this can take double the time taken above.

The removed sludge is then treated in the second step. It is separated into oil, solid wastes and water. The process is done right in the storage chamber before pumping it out of system.

After removing and separating the sludge the tank will then be washed in the third stage. It involves the use of high pressure cleaners that washes the walls, roof and floors of the storage chamber. This process includes de-rusting by the use of sand blasting and may take between 40 to 60days. For two teams working concurrently, this may take around 30 days to complete. The external walls of the storage chamber also require another thirty (30) to sixty (60) days to de-ruts and de-paint. However if ultra-high pressure cleaner is used, this process can take very few days though it is more expensive.

There is a one step cleaning method that has been developed and used by some companies. In this process, diesel is pumped through nozzles in a jet fixed on the receptacle's roof. This washes the sludge dissolving it after which the sludge/diesel mixture is pumped out of the storage chamber.

Even though this method is more efficient than the conventional one, some sludge will still remain solid and stuck to the tank base. This may take up to four months to dissolve then the mixture is pumped out into another tank. This means that an extra receptacle is required to store the mixture before it I separated.

The other method is a two step washing procedure. This is very advanced and way more effective than the first two. Very fast in cleaning and recovers more crude oil in the process. The first step is the use of a rotary jet mixer that is submerged into the sludge. It thoroughly mixes the sludge suspending it in the solution and recovers about 90% of the hydrocarbons. The machine needs 7 days to set up and only 3 days to complete the mixing.

This is followed by removing the remaining 10% sludge that is then very soft in comparison to the hard crust in the other methods. Given the violent mixing it has undergone, the sludge will not be a hard task to remove. This method of Crude Oil Storage Tank Cleaning is the most efficient and very time saving comparing 6 months for other methods and 10 days it uses.




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