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New Constructive Technologies – part one

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World Cement,

Clinker storage in Siniscola, Italy

In October 2015, Buzzi Unicem began work on a new clinker storage facility in Siniscola. The production, assembly and commissioning (July 2016) of the equipment and the full scope of supply was entrusted to B.S.P. Engineering.

B.S.P. Engineering has previously supplied Buzzi Unicem with silos for the storage of coal, flyash, cement and biomass, as well as cooling towers for their Robilante, Trino Vercellese, Siniscola, and Barletta plants in Italy and Luxembourg.

The whole project was designed by the technical department of Buzzi-Unicem, headquartered in Casale Monferrato, Italy.

The demanding design presented B.S.P. with a complex challenge for the engineering, production and installation of the main structures including silos, walkways, platforms to support filters at the quota of over 30 m and product weighing and dosing systems.

The new storage facility is composed of three silos (2000 m3, 4000 m3 and 8500 m3) intended to store three different types of clinker, which is dosed, weighed and mixed in different formulas after being discharged, according to required needs.

Machines intended for loading and unloading, product dosing and dust filtering have been partly constructed using salvaged materials from other Buzzi Unicem installations and partly are completely new.

For the three silos, B.S.P. Engineering suggested and applied a new constructive system: double folding spiral silos with internal continuous welding and external welding in sections.

The new system employs 5 – 7 mm thick metal coils that are spirally processed by a special machine that, by joining the edges of the unrolling coil and processing them with a double fold (outside and inside), erects the cylinder shell.

A robotic automated system secures the outside 90° folded metal sheet wall with continuous welding, and the inside wall with sectioned welding.

The simultaneous operations of unrolling coils and double folding/welding ensures the construction of the spiral tanks in a very short amount of time.

Skilled labour limited in quantity – approximately 3-4 people per silo – can erect silos ranging from 5 m to 36 m in diameter.

The use of up to 7 mm thick metal sheets greatly reduces the need for vertical stiffeners in the silo inner wall to safeguard the structure of the tank, thus accelerating the construction process.

Also interesting and convenient is the possibility of building tanks for liquids, where the thickness of the wall constitutes a fundamental element, particularly with the storage of fuels.

An outside coating made of pre-painted galvanised metal panels protects the silos wall from the atmospheric agents and contributes to the cooling of the stored mass of clinker by forming an air chimney that vents from the bottom to the top of the silo wall.

B.S.P. Engineering was also responsible for the design and the construction of the walkway on top of the silos. Due to the complex engineering, the heavy structure had to be anchored to the silo walls that were then reinforced to support the walkway’s weight and to withstand a 150 km/h wind.

Double wall silos in Ecocem site, Runcorn UK

Since August 2016 B.S.P. Engineering has been duplicating this at the Ecocem storage facility in Runcorn, UK and by assembling a second 7000 t silo (16 m dia. and with a height of 33 m) and a 250 t bulk forwarding silo.

The galvanised steel silo is going to be built using the same spiral double folding constructive system as its first twin silos.

An identical double wall erected all around the cylinder with the same spiral system creates a circular room that will be filled with concrete to reinforce the structure and counteract the lateral thrusts of the product against the wall of the silo.

Developed by B.S.P, these elements contribute to the resistance of the assembly: the three elements, inner shell, annular reinforcement and outer shell are considered as three rings acting in parallel thanks to the congruence ensured by the connecting concrete.

The small gap between the two walls (250 mm) allows the negative effects of the withdrawn concrete to be disregarded. However, these can be further minimised using a suitable anti-withdrawal additive.

The belting conferred by the folding creates a shell of equivalent thickness, with the surface of the single fold divided by the horizontal pitch of the fold itself. To ensure the belting effectiveness, the circumferential folding must be properly superimposed.

A steel mesh is welded to the first wall of the silo between the two cylinder shells. The circumferential room between the two walls of the silo is filled with top quality concrete casting (Top Flow) to prevent vibrations.

In Runcorn, B.S.P. has fully executed the engineering, manufacturing and construction of the silos, metallic structures, and fluidised hoppers to unload the product, as well as loading/unloading equipment such as bucket elevators with a flow rate of 150 m3/h, screw conveyors and telescopic dischargers.

B.S.P Engineering also installed Planetary Extractors at a 160 – 170 tph flow rate, to ensure the extraction of the product from the storage bins.

This is part one of a two-part article written for World Cement’s December issue and abridged for the website. Subscribers can read the full December issue by signing in, and can also catch up on-the-go via our new app for Apple and Android. Non-subscribers can access a preview of the December 2016 issue here.

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