The Ma’aden Waad Al Shamal Phosphate Company (MWSPC), based in Saudi Arabia, operates some of the largest and busiest fertilizer plants anywhere in the world. The Umm Wu’al sulfuric acid and power plant is an example, located in a new industrial city in the extreme northeast of the kingdom. Structured around three sulfuric acid trains containing a total of nine vast process towers, it produces almost 14 000 t of fertilizer a day. As well as bringing wealth to this remote region, its integrated power plant provides 150 megawatts of clean electricity to the local population.
So, when the company was looking to upgrade the facility, and replace the original towers with cleaner, more efficient equivalents, it needed to keep downtime to an absolute minimum. To compound the issue, the towers had originally been stick-built, not designed to be lifted in one piece when they needed to be replaced. The conventional approach for dismantling them piece-by-piece would take several months for each train.
Fluor, the project consultant, reached out to Mammoet for an audacious solution – to lift out the old towers in one piece. With careful planning, sophisticated computer modelling, the right equipment, and an expert team, Mammoet was able to develop the solution to delicately lift out the old towers intact, then manoeuvre the modular replacements into position.
To convince MWSPC and Fluor that this unlikely operation could be achieved, Mammoet prepared a detailed engineering study. 3D digital models of each tower were supplemented by a series of ultrasonic tests to reveal their true structure and strength. A finite element (FE) simulation showed how they would respond to the pressure of being hoisted out of the plant. And a series of bespoke frames and slings were designed to safely cradle the towers throughout the move.
A key requirement was to draft in the right equipment, and Mammoet had the ideal tools for the job, in the shape of two crawler cranes – the 1600 t capacity CC8800-1 and 1250 t capacity CC6800 – and the 3,200t MSG-80 ring crane. With this combination, it became possible to reach far above the tight confines of the site, extract all nine of the towers, move them to a central staging area, and hoist the replacements into position.
Abdullah Terkaoui, Project Manager for Mammoet explains: “Our methodology enabled our customers to reduce the planned shutdown schedule for each train from 120 days to 45 days. Then, as the operation progressed, further time savings were realised: the complete shutdown of the first train was completed in 30 days; the second shutdown, where the lifts took only seven days, enabling completion in 22 days; and, for the third, the lift took just three days, with a total mechanical completion in 19 days.”
Source: worldfertilizer
