High-Capacity Conveying Solutions for Fly Ash

Fly ash is a byproduct generated from coal- and biomass-fired boilers — fine at the micron level, with a high silica and alumina content, and both abrasive and prone to dust generation. Due to its low bulk density, variable moisture content, and high abrasiveness, standard pneumatic solutions in transfer systems can quickly lead to problems such as wear, blockage, and high energy consumption.

VOLDE Fly Ash Transfer Systems are designed with dense-phase pneumatic conveying technology developed specifically for this challenging material character. The goal is to safely convey the ash at low speed, under controlled pressure, and in a way that maximizes line life.

| Dense-Phase Design Specific to Fly Ash

Typical properties of fly ash:

• Fine particle distribution between 5–150 microns
• High abrasiveness (particularly due to SiO₂ content)
• Bulk density between 0.6–1.2 t/m³
• Low flowability and a tendency to bridge
• Being hot and dry at the filter outlet

DENSPLUS, developed with these properties in mind, is VOLDE's dense-phase pneumatic conveying tank. Operating on the pressure vessel principle, the system dispatches fly ash into the line in "slug" flow form.

Thanks to this:

• In-line conveying speed drops → elbow and pipe wear is reduced
• Air consumption is optimized → energy cost decreases
• Trouble-free conveying is achieved over long distances (100 m+ and beyond)
• Reliable operation is achieved at high capacities (tons/hour)

DENSPLUS tank volume, fill-discharge cycle time, operating pressure, and line diameter are determined through engineering calculations based on plant capacity and ash flow rate.

| Wear Control – Support Air Kits

The most critical issues on fly ash dense-phase lines are pressure fluctuation, dispersion of the material column, and wear at elbow sections.

AIRPLUS is a support air kit integrated onto the pipeline. Through controlled, low-flow-rate air injection, flow balance is maintained throughout the line.

AIRPLUS's contribution to fly ash transfer:

• Maintaining the continuity of the material column on long horizontal lines

• Providing stable transitions on vertical risers

• Reducing friction and wear load at elbows

• Balancing pressure spikes

• Minimizing the risk of blockage

Particularly in high-silica, abrasive ash transfer applications, the combined use of the DENSPLUS dense-phase tank and AIRPLUS support air kits significantly extends system lifespan.