Power reduction okofen = poorly burned granule ...

[chatelot16]

chemistry calculates the total amount of air for burning wood ... but the question is not there! the quantity of primary air is much lower ... it is with secondary air that the gas produced by the first combustion finds something to burn

if all the theoretical amount of air were sent under the pellets it would cool them so much that it would no longer burn!

the quantity of primary air must therefore be just enough for it to burn well ... if it is too much it cools too much and it will go out

if it is not enough it does not burn all the pellets ... so it accumulates ... and depending on the shape of the burner it can overheat under a layer of pellets

if the primary air is too strong before turning it off it does not start to cause the fires to fly: too much spark going up in the air ... too much dust to clog up the whole boiler

[Did67]

So the wood has 40% cellulose and 35% lignin, at worst !!

.

Yes.

Betrayed by my memories. And the mistake of not having checked. So 100% all wrong for me. My excuses.

[Did67]

if it is not enough it does not burn all the pellets ... so it accumulates ... and depending on the shape of the burner it can overheat under a layer of pellets

if the primary air is too strong before extinguishing everything it does not start to make the fire fly:

This does not happen on the Okofen volcano burner, where the pellets arrive from below and from the inside, then find themselves pushed onto the perforated disc where they are burned.

Lack of primary air would result in incomplete combustion and incompletely burnt pellets falling into the ashtray, along with the ashes.

In any case, the settings allowing only a limited variation around the "average point" (there is automatically dosage of the pellets supplied and the air blown in - fan and supply screw are driven by motors "not with "piloted" steps). So an excess will never reach the point where it would blow everything away ...

[chatelot16]

at my place there is no okofen: there is a brick hearth and a canister vacuum cleaner mounted upside down to blow, with a dimmer to choose the right flow rate

so all the excesses are possible for me ... and what I choose at the moment is rather the low primary air flow, the accumulation of fuel and the melting of ash in the bottom

coming out above the fuel the gas finds secondary air and burns well without smoke or dust

[Did67]

It's just that we are on a thread called "Okofen power reduction = badly burned pellet" ...

So I repeat what you say. I do not think that the problem as you state it applies to Okofen, therefore to the problem posed by Bedouin [it seems to me?], At the beginning [I do not say that what you say is false!].

[dedeleco]

So 100% all wrong for me. My excuses.

It is not 100% false, but very little, at 45 to 35% false and I forgot the lignin, which is not cellulose.
in addition I find it instructive to learn and clarify !!

In any case the optimum is a minimum primary air for pyrolysis and secondary to burn everything.

The most interesting would be an automatic feed for any wood, log that advances or chips, with a simple pre-drying, if necessary, instead of being blocked with standardized pellets.

I am not convinced that the current solutions are the simplest possible.

With a microprocessor, the air conditions can be automatically adapted to the fuel with the right sensors, especially in temperature.

[chatelot16]

of course if the okofen is properly studied, the possibility of adjustment remains limited to what is useful, not to excess!

what I meant is that the primary air is necessarily much weaker than what would be calculated by chemistry, and must be determined empirically ... it would not surprise me that the setting should be changed from delivery of pellets to the other without being able to say whether one is better than the other since both will burn perfectly with the setting that suits them

[chatelot16]

With a microprocessor, the air conditions can be automatically adapted to the fuel with the right sensors, especially in temperature.

the microprocessor can calculate everything, but it does not do the main work ... it can not pass wood into chips in a small screw that only passes granular

I fully agree that it is better to make a boiler burns everything than only pellet, but it is more complicated than putting a microprocessor

[Did67]

It is not 100% false, but very little, at 45 to 35% false and I forgot the lignin, which is not cellulose.
in addition I find it instructive to learn and clarify !!

Yes Yes ! I had 100% in the sense that, without checking, I was convinced that the wood was essentially lignin with a little cellulose, "straw" products (straw, dried miscanthus, old hay, etc.) .) being the reverse (a lot of cellulose and a little liginin - this depending on the age of the plant in the case of fast growing plants).

[Did67]

To come back to the question of the quantity of O²:

- theoretically, it should be determined for each batch, the composition of the wood varying ...

- In practice, by standardizing the pellets, the variation margin is considerably reduced and an average setting is close to the optimum; some manufacturers adding a lambda probe so that the control of the boiler takes into account the quality of the pellets ...

- we must not forget that in general, wood is very very very badly burned by ordinary people (I am talking about the classic "smothered driving" of stoves and inserts and even boilers when they are not 'have no buffer or controlled heating circuit); this must represent 80 or 90% of the situations ...

- the pellet boiler seems to me to be a solution that is certainly "very technical" (electronic board), with all the risks involved (but I always remember that any HDI engine is 3 times more complicated, works 15 years and no more 'scares anybody!), but it "relieves" the user of a lot of stress, while achieving a level of combustion cleanliness that the common of smortals do not otherwise ...

- this has its price (and perhaps some risks - dependence on a sector; for the moment, this is not a problem)

- that does not invalidate the "research" of enthusiasts such as you, chatelot, who can possibly succeed in doing better (I do not know all the same? would need analyzes of your emissions - without offending you, except filtrations, installations more plauqettes emit more simply because the fuel is basically wetter); but how many lmabda citizens are capable of doing what you do, or of following you (question settings) if you "tinkered" with them an installation ...

Where it gets tough (and that's why I'm a little "boring" with you, chatelot) is when your posts (necessarily brief) let the common people believe that by burning wafers, wet "like that ", or waste, without" quibbling "the boiler, it will be as clean as if it had opted for pellets ...

Of course, if you fine-tune "by hand" than a processor would automatically, this is no longer true.

But you see, I manage to forget my boiler and empty the overflowing ash box! While having a "top" combustion ...