Pyrotec 950 Underfeed Combustion Boiler

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The 'Pyrotec 950' is a Biomass Boiler, manufactured by Viessmann and produces 950 kWinfo.png
'950 kW'

Last calculated 77 weeks ago
 from wood fuels with a moisture content < 50% such as Forestry Waste.

The unit is designed to burn wood pellets, wood chips in various forms. Currently, it is not approved for non-woody biomass fuels.

The 950 kW unit is equipped with a 60 tonnes vertical storage hopper and auger feed system, designed for pellet fuels.

The estimated fuel requirement is 425 to 475 tonnes per annum.

The ash fuel specification limit is 1.5%.

It has a conversion efficiency of 0.85info.png
'0.85'

Last calculated 77 weeks ago
.

Contents

Key components of the boiler

The arrangement of key components of the boiler are as follows[1]:

  1. a feed auger moves the wood fuel into
  2. the burner trough with internal grate
  3. an attached external grate and
  4. a horizontal moving annealing grate
    • where the fuel is pre-dried and gasified under precisely controlled primary air to produce syngas.
  5. precisely controlled secondary air is injected
    • to ensure full combustion of the syngas
  6. air flow is effected by an ignition fan
  7. a deashing system is provided
  8. the combustion of the syngas occurs in a high-temprature burn-out zone
  9. access to the combustion can be gained through a chamber door
  10. thermal energy is released into the boiler’s triple-pass heat exchanger
  11. the tubes of which are kept by means of a pneumatic cleaning system

Fig. 1 Viessmann underfeed boiler

Fuel requirements

Bulk densities, water contents and sizes of classes of feasible wood fuels

Viessmann's specification of the bulk densities, water contents and sizes of classes of feasible wood fuels in biomass boiler plants are tabulated in Section #5 of 'Wood Fuels Minimum Requirements/Information', Viessmann Operation and Maintenance manual 5443 117 v1.2[2]::

Wood type Viessmann Code Bulk density Water content Size Code
Sawdust (planing shop) a) 130 (8.1) 10 to 20 C1
Sawdust (sawmill) b1) 200 (12.5) 20 to 35 C1
Forest wood chips, soft b2) 200 (12.5) 20 C3, C4, C5
Forest wood chips, soft c1) 250 (15.6) 20 to 35 C3, C4, C5
Sawdust, (sawmill) c2) 250 (15.6) 35 to 50 C1
Forest wood chips, soft/hard d1) 300 (18.7) 20 to 35 C3, C4, C5
Forest wood chips, soft d2) 300 (18.7) 35 to 50 C3, C4, C5
Forest wood chips, hard e1) 350 (21.8) 20 to 35 C3, C4, C5
Forest wood chips, soft/hard e2) 350 (21.8) 35 to 50 C3, C4, C5
Forest wood chips, soft e3) 350 (21.8) 50 to 60 C3, C4, C5
Forest wood chips, hard f1) 400 (24.9) 35 to 50 C3, C4, C5
Forest wood chips, soft/hard f2) 400 (24.9) 50 to 60 C3, C4, C5
Shavings & chips from wood remnants, mixed g) 130 (8.1) < 15 C3, C4, C5
Shavings & chips from wood remnants, mixed h) 200 (12.5) < 15 C3, C4, C5
Shavings & chips from wood remnants, mixed i) 250 (15.6) < 15 C3, C4, C5
Briquettes from wood remnants 20 mm to max 60 mm j) 350 (21.8) < 15 P3
Pellets conforming to standards, up to 10 mm k1) 650 (40.6) < 10 P1
Pellets conforming to standards, 10 mm to 20 mm k2) 650 (40.6) < 10 P2

Notes:

  1. Units of bulk density are: kg/m3 (lb/ft3)
  2. Units of water content are: weight %
  3. Size Code is as per CAN/CSA-B366.1-M91
  4. Viessmann Code refers to the labels used in Section #5 of Wood Fuels Minimum Requirements/Information in the Operation and Maintenance manual 5443 117 v1.2

Limits on ash composition to qualify as a fuel to Viessamann boilers

Ash is prepared at a temperature of 815oC, according the Chinese coal ash standard.

The limits on ash composition, expressed as mg/kg (db) are as follows[3]:

Ash component Limit Min. or Max.
Chlorine 300 max.
Sulfur 1000 max.
Total Cl, S 1000 max.
Ash content, total 15.0 max.
Alkali oxides (K2O, Na2O) 1.0 max.
Sintering point of the ash 1000oC min.

References

  1. ↑ Viessmann Pyrotec wood-fired boiler
  2. ↑ Section #5 of Wood Fuels Minimum Requirements/Information, Viessmann Operation and Maintenance manual 5443 117 v1.2
  3. ↑ Minimum requirements
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Facts about Pyrotec 950 Underfeed Combustion BoilerRDF feed
Efficiency0.85info.png
'0.85'
  +
FeedstockForestry Waste  +
ManufacturerViessmann  +
NameplateCapacity950 kWinfo.png
'950 kW'
  +
ShortName'Pyrotec 950'  +