La Robla Sulphur elimination plant
Project management:
Execution period:
Grupo Cobra - Plantas Industriales
3,500,000 €   
Grupo Cobra
February 2007 - December 2007  
La Robla, (León)


The construction work to be carried out in the Sulphur Elimination Plant in La Robla power station (CTR), consists principally in preparing the terrain  (earth-moving and demolition), construction of foundations for the equipment, auxiliary structures and buildings, construction of buried channels, buried drainage tanks and pits for equipment, execution of the buried earthing system and the urbanization of the areas.

1) Preparing the terrain:
• Avenue channel wall.
Earth movement:
• Filling in the avenue channel.  (800 m3. approximately).
• Separation wall for the coal yard.
• Wall about 60 m. long and 1m high on the terrain for separation of the absorber area from the coal yard.

2) Buried tanks and pits:
The buried tanks and pits are:
• Drainage tank for the absorber area.
• A tank with reinforced walls and floor, with a reinforced concrete covering slab.
Built using shoring. The bottom of the tank was under the water table.
• Drainage tank for the lime area.
• A tank with reinforced walls and floor and a reinforced concrete covering slab.
The bottom of the tank is under the water table. The slab at the bottom of the tank is supported by piles.

• Drainage tank for the gypsum area.
• A tank with reinforced walls and floor and a reinforced concrete covering slab. The slab at the bottom of the tank is supported by piles.
• Tape ditch: Formed by two adjoining cubes.
Foundation work was carried out in all action areas. The equipment the foundations are made for is:
• Gas conduit connecting the chimney and the gas by-pass.
• Foundation slabs grouping adjacent supports.
• Backup fan. Foundation slab measuring 10 x 5 m2. and approximately 1m thick and short columns to support the equipment.
• Oxidation blowers. Foundation slab to hold two or three pieces of equipment of about 6 tons each, occupying an area of 6 x 3 m2. approximately.
• Gas heater. Foundation slab measuring 16.5 x 16.5 m2. area approximately and 1 m thick.
• Absorber. Circular foundation ring measuring 21.05 m. in diameter and 80 cm. thick and an interior 30 cm. slab.
• Externally it will have an embedded channel 0.2 m. wide by 0.5 m. deep.
• Recirculation pump building/electrical building. The building measures approximately 18.8 x 15.6 m2.  The foundations are formed by a slab measuring approximately 17 x 18 m2. and 1 m thick with several foundation beams 40 m. long, 1.5 m. wide and 1 m thick, in addition to the floor made of composite decking type PF 76/383.
• Recirculation pumps.
• Lime slurry emergency tank with a circular slab.
• Gypsum bleeding pumps and emergency pumps for lime slurry.
Limestone building:  
The building measures approximately 18.5 x 25.5 m2. with 5 gates. Six of the building’s pillars (two gates) support two silos weighing approximately 900 tons each when in operation and other equipment. The foundation of the pillars were pile capped supported by piles and tied by beams. One of the gates supporting the silos rests on the pit walls.
Next to the building is the material reception building, which has foundations of tape pits. All the flooring in the gypsum drying area had been built with composite decking type PF-76/383 and a 28 cm. thick slab.
• Lime mills. Each of the mills will be on a slab supported by piles from which the support blocks for the mills, reducers and other auxiliary elements will arise.

3) Lime slurry tank, filter feeding, filter return, and process water:
The foundation of these tanks will be made with slabs with piles.
Water treatment plant area:
• Water Treatment Plant.
• Rack. The metal rack is about 250 m. long by 2.5 m. wide with supports every 6 m. on individual footing.

4) Buried channels:
The following buried networks will be made:
-For rainwater.
-For electricity-instruments.

5) Earthing network:
Consisting of a network of buried earth connections enabling the structures and equipment of an area to maintain the same potential. Composed of rings of bare copper directly buried in trenches, grounding pegs in junction boxes and potential control junction boxes.

6) Urbanization:
Urbanisation work consisted in paving the affected areas, building roads to connect the areas, outside of the CTR and water treatment, collection of rainwater and enlargement and reforms of the fence of the CTR to include the new outside area.


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