Moving grate firing system UTSR

Operating medium: water / hot water / steam
Grate cooling: Air / Water
Operating range: 150 - 6500 kW
Capacity regulation: modulating
Water content: M 10-60
Fuel types: woodchips / bark / residual wood / pellets / alternative fuels


  • Wood chips furnaces for private and public installations.
  • Bark furnaces and residual wood furnaces in sawmills.
  • Residual wood furnaces in the wood-processing industry.
  1. Fuel supply with hydraulic feeder, single or double stoker
  2. Primary combustion chamber
  3. Air-cooled horizontal moving grate
  4. Under-grate de-ashing – automatic or manual
  5. Automatic grate ash discharge
  6. Access to the secondary combustion chamber
  7. Radiation vault
  8. Refractory concrete for heat storage
  9. Secondary combustion chamber – in accordance with low NOx process by means of air control
  10. 13-pass steam boiler
  11. Boiler door with automatic pulse-jet cleaning system of the boiler tubes
  12. Flue gas cleaning by means of multi-cyclone with automatic fly ash discharge
  13. Flue gas fan – can be positioned either on the right, left or at the rear
  14. Grate door with safety lock
  15. Access door to undergrate

The UTSR boiler unit is equipped with a flat feed grate and also suitable for fuel with a high ash content. The fuel is passed into the furnace from the rear of the furnace on the flat feed grate with high-alloy casting grate bars. The grate bars are designed that they overlap on both sides and the minimum fuel slips through the grate. Furthermore, the grate is designed to enable a clear, uniform distribution of the primary air supplied to the various zones, thereby creating a steady, undisturbed gasification zone. The grate carriage has a hydraulic drive, so that the movement intervals can be automatically adjusted to the capacity. The complete combustion chamber is lined with fireproof material, thereby producing a high furnace temperature even in case of wet fuel. An additional, full-combustion roof with furnace lining is provided above the radiation cover in the combustion room, which varies according to the fuel. The secondary air supplied to the combustion chamber and the full-combustion stage makes possible a stepped combustion that results in optimum combustion and a reduction in the NOX value in the exhaust gases. This results in low emission values. The ash is transported slowly to the end of the grate and then to the automatic ash removal system. If so desired, an ash removal system can also be installed under the grate. With this system, any fuel that falls through the grate is transported with the grate ash directly to an ash bucket or container, by an ash screw conveyor.

Combustion chamber design

  • Insulation of the combustion chamber (100 mm) with external cladding plate
  • Air cooling inside double-wall steel plate construction (5-5, 6-8, 8-10 or 10-10 mm)
  • High temperature resistant heat insulation board (60/75/100 mm)
  • Fireproof ceramic fibre mat coated with aluminium foil (13/25 mm)
  • Fireproof cast concrete (115-150 mm)

The refractory concrete is secured to the steel structure of the combustion chamber with heat resistant wall anchors. The refractory concrete has a high density as well as a high temperature resistance and is cast in sections. Dilation seams between the sections compensate for expansion of the refractory concrete when the temperature fluctuates. The ceramic fibre mat behind the refractory concrete and the high temperature resistant heat insulation board protect the steel plate structure against overheating.

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