Preparation & Handling of Alternative Fuels (AF)

Waste for Cement Kiln Firing – Examples

 

Alternative Fuel Preparation – Why?

• Alternative fuel preparation is required to change the waste’s physical properties.

-Granulometry (Size)

-Water Content

-Foreign Bodies

-Viscosity

• A homogeneous alternative fuel allows a higher substitution rate.

Alternative Fuel Preparation – How?

Solid Waste – Example Waste Tyres

 

Solid Waste – Cost of Shredding

Solid Alternative Fuel Installation – General Flowsheet

Size Classification of Solid AFs

Storage & Extraction of Alternative Fuels

Storage & Extraction – Fine Solids

Storage & Extraction – Lump Fuel

Pneumatic Kiln Feeding

Guidelines

-Separation of oversizes & metals

-Introduction to pneumatic transport through a rotary valve

-Pneumatic transport as short and straight as possible.

-Injection through a pipe, parallel and on top of the main burner, or a central channel if available.

Gravimetric Kiln Feeding

• Actuated double or tripple pendulum flap gate

 

• Actuated shut-off gate(s)

-Protection of AFR feeding system during upset kiln operation.

-De-coupling of AFR feeding system.

Liquid AF Installation – General Flowsheet

Filtering

• Discharge filter is mandatory
  (for pump protection and to avoid atomizer blockage)
• Standard solution: Double basket filter (manual cleaning)
• Screen size depends on fuel specification:
  Recommended 1.5 mm, max. 5 mm (for good atomization)

Storage & Mixing of Alternative Fuel in Cement industry

• Minimum 2 tanks (one for kiln feed, one for new deliveries)
• Vertical installation
• Conical or rounded bottom
• Continuous mixing with mechanical agitator (circulating flow only second choice)
• Retention wall
• Fire protection (water and foam)

Kiln Feeding Pumps for Liquid AF

• 2 Pumps in parallel (one stand by)
• Spec.: Particles (wear), continuous flow (no pulsations) and high pressure
• Standard pumps for liquid AF:

Screw Pole Pump

-little pulsations

-not suited for very abrasive solids and solvents

Membrane Pump

-large pulsations

-suited for solvents

Flow Measurement & Injection

Coriolis Type Flow Meter

• no wear parts, no flow restrictions
• simultaneous measurement:

-flow rate [m3/h]

-Density [kg/m3]-  correlation to water content

-Temperature [°C]

Two-phase Nozzle

• atomization with pressurized air or steam
• design of atomizer depends on max. particle size

 

for more information please contact us