Description of Operation
Sand leaves customer’s mechanical reclaim silo through a metering device and is deposited onto the belt conveyor 1. Sand is discharged from the conveyor into the thermal reclaimer’s first stage, along with air 2 preheated by the sand exiting the reclaimer. The sand is electrically preheated from ambient 3 to a temperature where ignition of LOI materials will start to occur. At this point, combustion of materials not only includes carbon and organics with higher vaporization temperatures, but also the lower temperature VOCs formed during preheating 4, as they are entrained along with the sand and combustion air into the midsection 5. In the midsection of the thermal reclaimer the temperature of the sand and combustion gases increase to 1300-1400 F, allowing for complete combustion of all VOC’s, thereby eliminating any smoke or odor. As the sand and gases continue towards the discharge end 6, they are cooled by the counter flow incoming combustion air 2. The sand is discharged into the cooler at 1100-1200 F 7.
The cooler is comprised of two sections. In the inlet section 8, the sand is cooled by air. This reduces the sand temperature from 1100 to approximately 300 F. The discharge section 9 primarily uses water cooling to reduce the sand temperature to 15 F or less above ambient. By utilizing a two stage process, the efficiency of both air and water cooling is maximized. The cooled sand is then discharged into an extremely compact dense-flow pneumatic sand transporter 10 where it can be conveyed to storage 11.
The entire thermal reclamation system is controlled by a single PLC based control cabinet. The foundry’s peripheral equipment (such as bindicators, dust collection, etc) can be easily integrated into the system for fully automatic operation.
