Operating a 500-tonne mobile crane for 24-hours a day, at heights of 50 metres and a load exceeding 100 tonnes in highly constricted work conditions is no mean feat. Despite these challenges, Babcock’s plant services business concluded an economiser replacement project in March for Sappi Saiccor four days ahead of schedule, mainly due to the efficiency and planning of the managing contractor.
The contract
Babcock was contracted to provide cranage and full rigging services for the economiser replacement project by Austrian-based company, Andritz, who was commissioned by Sappi Saiccor to replace four economisers for their MGO2 recovery boiler.
Babcock’s scope of work began on 14 March 2017 and was completed less than a month later on 6 April, and included:
- Strand jack system and rigging service at a roof level of 50 metres to lower the old economiser units onto a 27m high sliding platform, with the heaviest unit weighing 160 tonnes
- Cranage and rigging services to lift the economiser units from the sliding platform to ground for scrapping and removal
- Installing the new economisers and precisely positioning the new units at ground level for welding together.
The crane configuration had to be changed four times during the project and the conditions were tough. The clearances when lifting the original economisers from the sliding platform proved challenging. The team had to be mindful of the limited space available and the crane’s lifting capacity. Despite these challenges, the boiler was returned to full operational capacity three days ahead of schedule.
Additional work required for the pre-lift and post-lift consisted of the installation and removal of the 17-tonne sliding platform, removal and replacement of the boiler venturi pipe through the roof level, and the removal and replacement of various roof steel and other support beams.
Star of the show
The star of this achievement was the Liebherr LTM 1500, a universal-use mobile crane with an extensive range of boom systems. Liebherr’s award-winning VarioBase system allows the crane to be used flexibly and efficiently with precise measuring and control.
The Liebherr LTM 1500 mobile crane has a maximum lifting capability of 500 tonnes at a 3-metre radius. The telescopic boom extends to a limit of 50 metres in length and the lattice jib can be utilised in lengths from 21 to 91 metres. Its load capacities can be increased even further with its Y boom guying (a cabled anchor system).
The client
The Sappi Saiccor Mill is situated 50 km south of the port of Durban and is one of the production facilities for Sappi Specialised Cellulose. The mill has the capacity to produce approximately 800 000 tonnes of elemental chlorine-free (ECF) dissolving wood pulp (DWP) per annum, mostly for the export market.
A large amount of steam and electricity is required by the mill which is produced by six coal-fired boilers and a chemical recovery boiler, with economisers used to reduce energy consumption by recycling energy produced or by leveraging environmental temperature differences to achieve efficiency improvements in a safe and environmentally.