Pyroflex FSB

Flat moving grate firing system 180 to 2600 kW

The flat moving grate firing system is parti­cu­larly suited to the combustion of wood fuels with a water content up to 55% and an ash content of 6%. Key advan­tages include the use of a variety of fuels plus a low dust content in the flue gas thanks to the resting fuel bed.

Flat moving grate firing system FSB

State-of-the-art combustion technology

Logging and sawmill scraps
Wood from lands­caping
Wood processing scraps

The Pyroflex FSB is charac­te­rised in parti­cular by flexible use of various wood fuels plus a low dust content in the flue gas thanks to the resting fuel bed.

Flat moving grate firing system

We generally use low-NOx reduction technology in our flat moving grate firing systems. The combustion chamber is equipped with an NOx emission reduction system on the primary side. Regulation of the primary air supply together with flue gas recir­cu­lation ensures substoi­chio­metric combustion in the reduction zone. Secondary air is injected into the oxidation zone within the ceramic-lined portion of the combustion chamber. This air injection ensures high turbu­lence and mixing with the flue gas, resulting in optimal oxidation (CO burnout) of the combustion gases. Ideal emissions values are achieved thanks to these measures.

Minimal life cycle costs

We place the utmost impor­tance on durability and a long lifespan for our systems. This is achieved by using robust system components. Solid steel construction for the biomass boiler and the use of high-quality refractory material guarantee reliable system availa­bility for many years. Minimal power consumption in all load states of the system is ensured by frequency-controlled screws, grate drives and flue gas recir­cu­lation.

Equipment and access­ories

Type Output range*
FSB 180 45 to 180 kW
FSB 220 55 to 220 kW
FSB 280 70 to 280 kW
FSB 350 87 to 350 kW
FSB 440 110 to 440 kW
FSB 550 137 to 550 kW
FSB 700 175 to 700 kW
FSB 850 212 to 850 kW
FSB 1100 275 to 1100 kW
FSB 1400 350 to 1400 kW
FSB 1700 425 to 1700 kW
FSB 2100 525 to 2100 kW
FSB 2600 650 to 2600 kW

*Depending on fuel and water content


The Pyroflex FSB is tested and certified according to the Machinery Directive and DIN EN 303-5 and is subject to conti­nuous monitoring by TÜV.

Sectional drawing FSB
  1. 3-pass boiler (6 bar – higher pressure ratings on request)
  2. Safety heat exchanger (integrated into boiler)
  3. Flat moving grate, hydrau­li­cally driven
  4. Injection of secondary air
  5. Injection of flue gas recir­cu­lation
  6. Inter­me­diate vault
  7. Automatic combustion chamber ash removal
  8. Fuel infeed, hydraulic or with screw
  9. Pneumatic boiler tube dedusting (optional)
  10. Firebox door

Profit from these benefits:

  • Fully automatic wood-burning system with flat moving grate
  • Fuel water content: 6 to 55%
  • Staged combustion (low-NOx technology)
  • Lower pollutant emissions thanks to resting fire bed
  • High efficiency (up to 92%)
  • 3-pass flame tube-flue tube boiler with flue gas tempe­ra­tures below 190 °C at full load
  • Highly insulated, fully ceramic-lined combustion chamber design and optimally designed combustion air supply guarantee complete combustion of all fuels
  • Safety heat exchanger integrated into boiler
  • Sliding load regulation from 25 to 100% of the rated heat output in compliance with the emissions values (fuel-dependent)

Optional access­ories

  • Pneumatic boiler tube dedusting (signi­fi­cantly extends the time between cleanings)
  • Automatic ignition system (automatic ignition for fuels with a water content of up to 35%)
  • Flue gas recir­cu­lation “under” the grate runs behind the lining. (Increases efficiency and reduces nitrogen oxides, plus cooling of the grate)
  • 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

Wholesale nursery (heating of green­houses)

Firing system: Pyroflex FSB
Output: 1700 kW
Fuel: Forest wood chips M45

Anlagenbeispiel FSB
  1. Fuel storage with moving floor discharge
  2. Hydraulic fuel transport with direct infeed
  3. Firing system Pyroflex FSB
  4. Ash removal from the combustion chamber into 800 l container
  5. Flue gas cleaning by electro­static filter with integrated multi­cy­clone separator
  6. Flue system
  7. Pneumatic boiler tube dedusting (optional)