STEEL BELT CONVEYORS FOR SEVERE CONDITIONS since 1929

KVA Horgen

THE CHALLENGE

Within the project to join the metals recovery facility at KEZO Hinwil, the wet-to-dry conversion of the bottom ash handling system at the Horgen CHP plant involved the replacement of the existing submerged chain conveyor with the Magaldi Ecobelt® WA conveyor.
In 2014, Hitachi Zosen Inova (HZI) awarded Magaldi a contract for the supply of a patented Ecobelt® WA (standing for waste ash) conveyor to be installed on the incineration line #2 at the Horgen CHP plant in Switzerland.

 

THE CUSTOMER

Hitachi Zosen Inova (HZI) is a global leader in energy from waste, acting as an engineering, procurement and construction contractor delivering complete turnkey plants and system solutions for energy recovery from waste.
Its solutions are based on efficient and environmentally sound technology. HZI’s innovative and reliable waste and flue gas treatment solutions have been part of some 500 reference projects delivered since 1933.
The final Client is KVA Horgen, a waste incineration plant located close to Zurich (Switzerland). The combustion line #2, completely refurbished in 2015, burns mainly household wastes and about 6,000 t/y of industrial wastes and 10,000 t/y of bulky wastes.

 

THE SOLUTION

Before the wet-to-dry conversion project, the bottom ash was removed by means of a wet submerged chain conveyor (SCC) installed underneath the combustion grate. In June 2015, Magaldi completed the installation of the Magaldi Ecobelt® WA conveyor, that receives both the fine ash particles, collected in the sifting hoppers, and the bottom ash discharged by gravity from the combustion grate.
The fine particles are discharged onto the conveyor through rotary valves, that have the function of isolating the hoppers at positive pressure from the downstream equipment at slight negative pressure. Since the Ecobelt® WA conveyor has a 40° slope, the steel belt is provided with cleats to avoid any roll back of material.
The amount of cooling air flowing into the furnace is limited by means of suitably designed belt skirtboards and special curtains hinged to the conveyor covers, which allow the passage of the bottom ash while preventing uncontrolled air backflow to the furnace.
The Ecobelt® WA is also equipped with the spill chain to recover the fine residuals from the bottom of the casing. Usually, the spill chain is intermittently operated due to the small amount of material to be conveyed. After cooling, the dry bottom ash is discharged onto a rubber belt conveyor, that is isolated from the Magaldi Ecobelt® WA through two hydraulic gate valves.
The bottom ash is finally unloaded into special containers and dispatched to the metals recovery facility at KEZO Hinwil. This innovative facility, designed to treat about 200,000 tons per year of bottom ash, is the first fully-dry slag recycling plant in the world.

 

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