Friday, December 27, 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.

In the conventional method, the sludge is removed from storage chamber's bottom, a process that can take between 90 to 120 days. This is done with experienced personnel and machines and with more operators, the stage can take less like 2 to 3 months. And when using receptacle cleaning machines that are remotely operated will take double the time as compared to human operators.

Once the sludge has been removed, it is treated. This results in it being separated into waste water, recovered oil and solid matter. All this happens inside the chamber after which it is pumped out of the storage chamber before cleaning.

The third stage is to wash the tank since the sludge has been removed. By the use of high pressure cleaners, the floor and walls of storage chamber are thoroughly cleaned and de-rusted by use of sand blasting. It can take around 50 days if one team is working on it or about 30 days for two teams working simultaneously. To clean the external wall by sand blasting, the operators will take another 30 to 60 days based on the number of teams working on it. Another more efficient alternative which is more expensive is to use ultra-high pressure cleaning which combines de-rusting and de-painting in one process.

Another method of Crude Oil Tank Cleaning is to use one step tank washing technology. This scientifically developed and is way more efficient as it washes in one step. It involves the pumping of diesel through nozzles installed on the roof of the storage chamber. This diesel washes the sludge after which the mixture of diesel and sludge is pumped from the receptacle bottom.

Using this method may be efficient but some solid sludge may take time to dissolve. For a 100,000KL tank this may take up to 4 months to dissolve. Temporary storage of the diesel/sludge mixture should be made as it is planned how to separate them into oil, solid and water. Another receptacle is required to contain the pumped out mixture when a receptacle is being cleaned.

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.

The second step can be skipped if the client feels so. But if there is a need, then the residual sludge is removed. And since it is only 10%, the process will take way less time. And after the thorough and violent mixing, the remaining sludge is quite soft and easy to handle as compared to when using the conventional method of Crude Oil Storage Tank Cleaning.




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