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13. GENERAL TECHNICAL TIPS
13.1. Settings and maximum allowed temperatures
High power boilers are often used to heat industrial plants in wood processing plants.
In such situations, the different processes wastes are frequently used to fuel the boiler.
Often the waste materials are very dry and contain synthetic resins and paints which should not be used as
fuel. Their thermal specific power is very high, and consequently the boiler output power and the smoke
exhaust temperature as well increase significantly
WARNING!: if the smoke exhaust temperature raises beyond 200°C, drafting fan motor problems may occur
(the bearings lubricating grease gets dry), the burner grate bar cast iron elements may quickly wear out, the
same thing happens to the catalyst elements and so on.
Therefore, we recommend to monitor the smoke temperature, proportionally reducing the combustion air
supply and mixing with the dry wood wastes other less dry wood with a lower specific thermal power.
For a proper operation of the boiler the smoke exhaust temperature must be in the range 150°C - 180°C.
If lower, condensation and corrosion problems may appear.
If higher, fan problems may occur and the burner bar elements and the catalyst may wear out quickly.
Obviously, a correct boiler setting “on the place” is required for the many specific thermal power differences
among the various wood types used.
13.2. First firing
Any kind of boiler, especially the high power models, require a progressive first firing to allow the refractory
parts to dry out completely.
At the first firing, we recommend to use only a small amount of wood, letting the water temperature raise
gradually, otherwise the outer layers of the refractory cement inner parts may detach, or cracks may appear.
In some cases, if the humidity cannot escape outside gradually from the cement blocks, dull explosions may
be heard.
13.3. Refractory cement components in the boiler
It is pretty normal that the refractory blocks show small imperfections.
For this reason, the refractory blocks thickness is overdimensioned; by this way, even if happens what
outlined above, (paragraph 16.2.), the boiler overall insulation degree is anyway maintained.
13.4. Boiler autonomy and fuel charging intervals
Under normal operating conditions, the boiler will require to be charged two times every day. With “normal
operating conditions” we intend using the boiler at an average output power about in the middle of the
recommended power range.
This is obtained if the building has a good insulation from the thermal point of view, for an external average
temperature around 5°C, etc.
In extreme conditions the fuel charging operations will be more frequent (3-4 every day), while in the middle
seasons a single charge will be enough.
13.5. Explosions
With low flue duct drafting action, when using very dry wood and too much wood logs charged in the boiler,
the gas released by wood can accumulate in the wood box; when the drafting fan starts again, the air-gas
mixture could cause noisy explosions. Anyway, the boiler won't get damaged because antideflagration doors
are present the in the back side.
Summary of Contents for ASPIRO DUO TECH
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