Changing from manual to automated tank cleaning saved time and money

At ESSO’s Fawley Refinery in the UK, the cat slurry tanks were in need of cleaning. Two main objectives were outlined for the project: Minimum downtime and minimum waste gen- eration. The BLABO automated system proved its strength on both accounts.

Over time, the Fawley Refinery cat-fines sludge tanks had built up calalytic fines strata and con- solidated sediments at the bottom. A thorough cleaning was called for, but two major criteria must be met: Minimum downtime and minimum waste – both crucial cost factors. STS, using the BLABO automated tank cleaning system, delivered.

Facts and figures

Location: Fawley Refinery (ESSO), UK
Contractor: STS Tank Cleaning Services
Tank capacity: Diameter: 39.46 meters  / Height: 14.60 meters
Tank content: Cat slurry
Roof: Fixedroof
Sludge content: 1,832 m3
Time consumpt.: 15 days
Recovery rate: 97.8%
Recovered oil: 1,791 m3
Value of rec. oil: USD 675,900 (USD 60/bbl)

From manual to automated cleaning
Before the BLABO system entered the scene, the Fawley Refinery had already cleaned one cat slur- ry tank through traditional manual cleaning. The process entailed high waste disposal costs and took longer than the company would prefer. Also, personal and operational safety was at risk. This prompted the management to try automated tank cleaning, eliminating the need for tank entry and ensuring an efficient, cost-effective cleaning process.

The cleaning procedure
STS entered the picture in March 2007. STS has over a decade of experience with safe, automated tank cleaning and oil recovery throughout Europe, and Managing Director Jorge Oteiza is a firm advo- cate of the Oreco BLABO system. Preparations and compliance checks complete, the modular, fully au- tomated BLABO system was mobilised on-site.

Nitrogen was introduced to create a safe atmosphere for tank cleaning. The target was 8% Oxygen vol- ume in air to eliminate the risk of explosion. With the atmosphere made safe, the desluding process began using any remaining oil in the tank as initial flushing medium. Then, heated LCO (Light Cycle Oil) washing was begun. The LCO was re-circulated through the BLABO system and back into the tank via the nozzles, simulatenously cleaning the tank and separating the hydrocarbons.

Says Mr. Oteiza: “Maximum hydrocarbon recovery is a key asset of the BLABO system. The value of this recovered oil is part of what makes automated tank cleaning a financially advantageous option.”

Washing complete, tank opened
The LCO wash was repeated until the high stand- ard specified by ESSO was met. Then, ejectors degassed the tank to raise Oxygen levels back to 20%, leaving it ready for operation.

Client pleased: “Cleanest we’ve ever seen”
The Fawley Refinery was very pleased to have its tank back in just 15 days. The results proved im- pressive; when the tank man-holes were opened, managers and supervisors all stated that they had never seen a slurry tank that clean in all their years in the business. And the results were not only achieved with speed; money was saved on waste disposal and, best of all, no people were subjected to any risk.


The cat slurry tank at Fawley Refiney in the UK was clea- ned by STS and ready for operation in just 15 days – and no staff had to enter it during the cleaning process.

Oreco A/S . Oldvej 1A . DK-3540 Lynge . Denmark . TEL. +45 4332 0200 .

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