UCC pioneered the first dry bottom ash system using pneumatic technology in 1920. The PAX Pneumatic Ash Extractor added new technology to this time-proven vacuum system design and offers many benefits over wet bottom ash systems. The PAX system eliminates the need for water, increases both combustion of unburned carbon and heat recovery to the boiler and reduces overall maintenance costs. For plant retrofits, the PAX system provides excellent routing flexibility around structural barriers.
Bottom ash is collected in refractory-lined hoppers under the boiler. Percolating air promotes combustion of unburned carbon, cools the ash, and protects ancillary equipment from the 1600°F ( 871°C) temperature. At the appropriate time, grid doors at the hopper bottom open to allow ash and clinkers to pass into a crusher and are fed to the vacuum system for transport to the dry storage silo or ash transfer truck.
PAX Pneumatic Ash Extractor:
- Zero water discharge – No contaminated water to treat and no ash ponds to maintain
- More complete combustion of unburned carbon – Better boiler efficiency
- No space required for pumps, tanks or re-circulation system
- Time-proven dependability of a vacuum conveying system
- Substantially reduced maintenance costs with no major recurring expenses
- Cleaner working area – No puddles
- Dry bottom ash can be sold and reused in environmentally-friendly applications.
When is the PAX system the most appropriate?[+]
The PAX system is the preferred retrofit system where structural barriers exist and where complete water elimination is required. It is also advantageous in applications where maintenance costs are major concerns.
How often is the bottom ash conveyed?[+]
The dry bottom ash hopper is normally sized for 8 hours of storage, which allows for conveying once per shift.
Where does the percolating air come from?[+]
A controlled positive pressure flow of air from the FD fan is directed through the crusher and ash pile. This air flow is regulated to approximately 1% of total combustion air with no adverse effect on boiler operation.
How can UCC crushers/clinker grinders withstand high ash temperatures?[+]
UCC EXCEN-CRUSHERS contain cams and anvil plates that have cast-in carbide wear surfaces to withstand the high temperature and abrasiveness of the ash.
– Nuvaloy, Durite, Dur-rok, Ceramic, Expansion joints, Connections
– 27”, 33”, 54”