Generally speaking, fly ash is the ash that has gone through the boiler furnace and steam generating bank sections. It is collected beneath the equipment in downstream hoppers, such as the air heater, economizer, precipitator, dust collector, baghouse, and so forth.
Let’s take a closer look at how fly ash removal systems work and how fly ash moves through your equipment.
What Makes Up Fly Ash?
Fly ash is usually made up of particles less than 100 microns in size, with material and flow characteristics that are extremely unique. Ash isn’t the only type of particle in fly ash, either—there’s also sand and dirt that came into the boiler process with the biomass. In fact, the sand and dirt may make up a significant percentage of the fly ash in biomass facilities that use bark, storm damage debris, or forest debris as a portion of the biomass portfolio.
The composition of the fly ash is an essential consideration when it comes to the fly ash removal system, because it must take into account the additional particles that may be present in addition to the ash.
The Design of a Fly Ash Removal System
Because of the lack of large, solid particles that could impose a large amount of force on the chain/flight setup, fly ash drag conveyors may be designed to work on a single strand drag chain design with arrangements of cantilevered flights. Such a design uses principles of “en masse” conveying—a very efficient method that allows for smaller conveyors and slower chain speeds for a specific volumetric output.
One of the benefits of a single strand drag chain is that uneven drag chain elongation is no longer a concern regarding the conveyer functionality. There may be some drag chain elongation, but it is easy to manage in the conveyer take-up mechanism.
When we can keep the bottom and sifting ash out of the fly ash removal system, we don’t have to worry about the presence of large, solid particles. In turn we can have a smaller, simpler fly ash drag conveyer design, improved conveying efficiency and reliability, and less future maintenance/repairs.
Interested in learning more about making your fly ash removal system more efficient? Contact ProcessBarron today.