Sand Cooling and Wetting Screws

Indispensable Auxiliary Equipment for Fluidized Bed Boilers

Sand Cooling and Wetting Screws are critical engineering solutions that increase the efficiency and sustainability of fluidized bed boiler systems. These systems provide both material savings and energy recovery by processing the bed material (sand) after combustion.

Working Principle: Step by Step Recovery

In fluidized bed boilers, the hot sand and ash mixture discharged from the bottom of the bed after combustion is processed by these special spiral systems:

1. Sand Cooling and Energy Recovery: High-temperature sand, removed from the bottom of the bed, enters a water-jacketed cooling spiral. As the sand moves through the spiral, it transfers its heat to the water circulating in the jacket. This recovers waste heat, producing usable hot water for the facility and cooling the sand to a safe temperature.
2. Elimination and Recovery: The cooled sand is directed through a screening system. The screening separates the appropriately sized, valuable bed sand from the larger ash and slag particles produced by combustion.
3. Feed Back to Bed: The screened, clean, appropriately sized sand is reused by feeding it back into the boiler's fluidized bed. This reduces the need for constant new sand, providing a significant cost advantage.
4. Ash Wetting: The ash and slag separated in the screen can be directed to a wetting screw. Here, the ash, mixed with water, is ready to be transported safely to storage or disposal sites without creating dust.

Key Benefits:

• Energy Efficiency: It provides energy recovery by producing hot water from the heat of waste sand.
• Cost Savings: It reduces consumable costs by recycling bed sand.
• Environmental Protection: It creates a cleaner working environment by preventing dust emissions through the ash wetting process.
• System Security: It increases operational safety by cooling the hot material in a controlled manner.