Pyroflex VFE

Direct firing system 850 to 8000 kW

The very dry, dust-like fuel is blown into the fully ceramic-lined and heavily insulated combustion chamber through one or more blowing lines. The combustion chamber geometry is specially designed for the blowing in of fuel to ensure optimally complete combustion of the fuel as well as the required turbu­lence and flow condi­tions.

Direct firing system VFE

The specialist for the wood industry

Very dry, dust-like fuels from indus­trial wood processing

Direct firing system with high tempe­rature residue combustion for energy production from dust-like wood scrap from wood processing.

Direct firing system

The fuel is blown in according to the injector principle. In other words, no fuel enters the blower fan, avoiding fan wear. The heat storage in the ceramic lining ensures corre­spon­dingly high combustion chamber tempe­ra­tures for very low emissions values. The horizontal 3-pass flame tube-flue tube boiler is installed on top of the combustion chamber as a warm or hot water boiler. Steam boilers or thermal oil boilers can also be supplied, if needed.

Designed for the wood industry

The Pyroflex VFE was specially designed for indus­trial wood processing. Even fuels like MDF or chipboard scraps pose no problem for this firing system.

The low-NOx combustion chamber is designed with primary-side measures such as air staging to reduce NOx emissions. Regulation of the primary air supply together with flue gas recir­cu­lation ensures substoi­chio­metric combustion in the reduction zone.

Secondary air is injected after the reduction zone of the combustion chamber. The corre­sponding firebox geometry combined with the combustion air injection ensures high turbu­lence and mixing with the flue gas, resulting in optimal oxidation (CO burnout) of the combustion gases.

Flue gas recir­cu­lation

The flue gas is drawn into the exhaust line and reintro­duced to the combustion chambers with a fan. This decreases the flame tempe­rature and reduces nitrous oxides. The efficiency of the system is increased as a result since a lower residual oxygen content remains in the flue gas, even in the case of dry fuels.

Equipment and access­ories

Measu­re­ments in the primary air and recir­cu­lation air

The flow rates of the primary and recir­cu­lation air are measured, and the required air quantities are calcu­lated in advance. This achieves optimal combustion results and emissions values in all load stages, including with difficult fuels.

Use of high-quality O2 probes

The secondary air flow rate is regulated based on the detected oxygen level. High-quality O2 probes make it possible to maintain a conti­nuously low residual oxygen level in the flue gas (approx. 5–6% O2 (damp) – depending on the fuel). This allows the highest levels of efficiency to be achieved even in modulating partial load operation.

Ash removal

Due to the in-flight combustion, very little ash remains in the combustion chamber. Ash can be removed from the combustion chamber either manually or automa­ti­cally using a water-cooled screw.

Sectional drawing VFE
  1. 3-pass boiler (6 bar – higher pressure ratings on request)
  2. Safety heat exchanger (integrated into boiler)
  3. Combustion chamber
  4. Blow-in ports
  5. Injection of secondary air
  6. Injection of flue gas recir­cu­lation
  7. Automatic ash removal from the combustion chamber using a water-cooled screw
  8. Firebox door
  9. Pneumatic boiler tube dedusting (optional)

Profit from these benefits:

  • Fully automatic wood-burning system with direct firing 850 to 8000 kW
  • Fuel water content: 6 to 15%, ash content (share of foreign matter) up to 2% (4% for upright combustion chamber)
  • Modulating load regulation from 55 to 100% in compliance with the emissions values
  • Stop-and-go operation: If the heating demand on the system falls below the minimum output, the system automa­ti­cally switches off and enters standby mode. If the supply tempe­rature falls below the target value, meaning heating is again required, the system is restarted. If the firing system remains idle for a prolonged period, the automatic ignition burner in the combustion chamber starts up and heats the combustion chamber back to the required tempe­rature for feeding in fuel.

Optional access­ories

  • Pneumatic boiler tube dedusting (signi­fi­cantly extends the time between cleanings)
  • Automatic ignition system
  • Optional two blow-in nozzles for modulating load regulation up to 35% (from 1700 kW)
  • Remote maintenance and visua­li­sation systems (full system access from a PC, tablet or mobile phone)
  • Raising of the flue gas tempe­rature (to avoid conden­sation in the flue gas path and in downstream components)
  • Nitrogen oxide reduction system (for reducing of NOx emissions with the SNCR method)
  • Conti­nuous emissions measu­rement


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Example instal­lation

Furniture industry (profiles and coverings)

Firing system: Pyroflex VFE
Output: 1700 kW
Fuel: Dust and shavings from production

Anlagenbeispiel VFE
  1. Fuel storage in a silo
  2. Fuel discharge with a pendulum screw
  3. Pneumatic fuel transport
  4. Firing system: Pyroflex VFE
  5. Automatic ignition system
  6. Flue gas cleaning by multi­cy­clone filter
  7. Gas-fired boiler for covering peak loads

Areas of appli­cation