A wet bottom ash handling system in a waste-to-energy (WtE) facility uses water to cool, quench, and transport hot bottom ash from the combustion chamber. The wet process controls dust and enables the efficient recovery of metals from the ash. The most common technology for this is a submerged scraper conveyor (SSC)
Key components and process:
Quench and collection hopper: Hot incinerator bottom ash (IBA), which consists of metals, glass, and other unburned inorganic materials, falls off the end of the furnace grate into a water-filled hopper.
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- The water immediately quenches and cools the hot ash, reducing its temperature and preventing dust from becoming airborne.
- A refractory-lined hopper with a water seal maintains a gas-tight seal at the bottom of the boiler to prevent air from leaking into the furnace.
- Submerged Scraper Conveyor (SSC): From the hopper, the cooled ash is continuously extracted and transported by an SSC.
- The conveyor uses scraper blades, attached to a chain, that drag the ash along the bottom of a water-filled trough.
- The low-speed movement (0.1–0.3 m/s) of the scraper chain provides a robust method for transporting the abrasive ash.
- Dewatering and discharge: The conveyor system inclines upwards to carry the ash out of the water-filled trough.
- This allows the water to drain away from the ash.
- The moist ash is then discharged to a crusher, which breaks down any large clinkers.
- Recycling and disposal: After crushing, the ash can be sent for further processing.
- Water-based processing, using jigs and density separation, can recover valuable ferrous and non-ferrous metals.
- The remaining inert ash aggregate can be reused as a construction material for road foundations or other civil wo
Advantages of wet bottom ash handling
Effective cooling: The water bath rapidly cools the ash, making it safer to handle and protecting downstream equipment from high temperatures.
- Dust suppression: The submerged environment effectively eliminates airborne dust emissions, improving worker safety and environmental compliance.
- Improved metal recovery: Wet processing methods, such as density separation, are more effective at recovering fine particles of precious and non-ferrous metals that are often lost in dry systems.
- Reduced wear and tear: Water lubricates the scraper conveyor and reduces the abrasive wear on the equipment compared to handling dry, hot ash.
- Enhanced final product quality: Wet-treated incinerator bottom ash aggregate has better environmental and physical properties, making it more suitable for use in construction
Post time: Oct-31-2025