Rocket fuel burner..... Silly question....

[manicman]

Hi all,
I've seen/read many posts on Rocket Fuel Burners with deep interest as I'd like to build one for my workshop ready for winter.... However, I've not seen any reference to what happens to the ash from the fire??? Could anyone shed any light on this as I've no idea how to deal with this???

Thanks
Ian

 

[Parm]

Hi all,
I've seen/read many posts on Rocket Fuel Burners with deep interest as I'd like to build one for my workshop ready for winter.... However, I've not seen any reference to what happens to the ash from the fire??? Could anyone shed any light on this as I've no idea how to deal with this???

Thanks
Ian

Good question, I'd be interested to see the responses !

 

[Paul99]

Hi all,
I've seen/read many posts on Rocket Fuel Burners with deep interest as I'd like to build one for my workshop ready for winter.... However, I've not seen any reference to what happens to the ash from the fire??? Could anyone shed any light on this as I've no idea how to deal with this???

Thanks
Ian

If you mean how to dispose of it - Once cool (get a metal bucket if you plan emptying the stove whilst still hot) it goes in normal household refuse - my grandparents still call the bin wagon an ash cart - back in the day coal ash and clinker was about the biggest reason a refuse collection service was set up by councils - there was very little else people back then couldn't deal with without having to resort to landfill. Of course you can also do what I personally do and spread it on the garden and flowerbeds - having sieved or picked out nails etc.

 

[rtbcomp]

If you burn wood (not rocket fuel) the fire sits on top of the ash, you don't use a grate, and when the pile of ash gets too large dispose of as above.

 

[manicman]

DOH..... I know how to get rid of it after it's been removed from the RFS but I mean how do you/RFS cope with where the ash goes INSIDE the RFS whilst the fire is still burning?

 

[Paul99]

If you burn wood (not rocket fuel) the fire sits on top of the ash, you don't use a grate, and when the pile of ash gets too large dispose of as above.

Although a grate shouldn't be needed I found mine better for adding one as I could keep it going for long periods - coals built up in mine as it gets smothered by ash and eventually the j-tube constricted to the point where smoke made it out the feed tube.

DOH..... I know how to get rid of it after it's been removed from the RFS but I mean how do you/RFS cope with where the ash goes INSIDE the RFS whilst the fire is still burning?

A rocket stove going well with good wood should produce little ash which should allow long enough burns before having to let it cool and scrape it out - but as above nothing wrong with adding a grate and ashpan to allow removal whilst hot - there's a few pics of what I did with mine here: http://www.mig-welding.co.uk/forum/threads/another-rocket-stove.44860/page-2#post-507800 which might give you some ideas.

 

[manicman]

Paul,
THanks for the link and yes it was a help... Although it has raised another question.....
I think I can see some plates down in the burn tube? Are these for creating a heat vortex? If so, what's the benefit of this and how should they be fitted?

 

[Wallace]

From what I have read up about rocket heaters there is very little ash if the temperature is high enough as everything gets burnt and the most efficient ones are made with fire bricks to withstand the temperatures and last as steel eventually burns out.

 

[Paul99]

Paul,
THanks for the link and yes it was a help... Although it has raised another question.....
I think I can see some plates down in the burn tube? Are these for creating a heat vortex? If so, what's the benefit of this and how should they be fitted?

I think what you mention is the secondary air tube - better photos of it on page 1 of that link. Simply a length of 30mm box running through the bottom of the burn tube which adds pre-heated secondary air to the bottom of the riser - which seemed like the best place to put it given what I had read about secondary air at the time. I added one both sides of the burn tube though I don't think I needed to one side would have likely been enough. They don't create any sort of vortex - that I did with crossed discs in the riser - again shown on the first page of the link. The secondary air is supposed to be there to add more oxygen to the bottom of the riser causing any remaining flammable gases to burn increasing efficiency and creating cleaner emissions - it has no effect until the stove is up to temperature and even then it's hard to actually see that it has a significant effect. I suspect that given the size of my J tube there is always an excess of air being pulled through the feed tube - this may not necessarily be the case with more conventionally sized j tubes in which case this extra pre-heated secondary air might make a marked difference.

Whether or not the way I did it is right or not I don't know but it works plenty good enough for now - I do plan to experiment more one day when / if I ever get to the end of the always growing list of things to do. It gets a bit addictive trying to improve what initially starts out as a very simple way to heat a shed but whether any of the extra work adding fancy bits is worth while or not isn't always that clear.

 

[Farside]

If it ever gets a sufficient supply of round tuits, there will be rocket stoves in my workshop and kitchen, the kitchen one being more of a mass heater type, but on the same principle.
Do you know the simplest rocket stove? Get ten ft of flue pipe with a right angle bend at the bottom and place a burning rag in there to light off the small pan of oil or wood bits. The natural draught is immense and you can see the hot spot develop on the flue pipe - it also makes a racket - the sound of power, I like to think of it as. I found this one out more than a decade ago when I was messing around thinking of ways to use up an immense pile of chip fat I'd built up, far more than I needed for biodiesel. The flue pipe hot spot got me thinking that would be a good place to put a water jacket, and if the flue was thicker walled it would last for a decent while, of course the heat being robbed away by the water would lessen its efficiency a bit, but easily compensated by more flue on top. Luckily I've got the height to do that with.
The reason I was looking at that was to burn oil outside - didn't fancy it indoors, not all that smelly muck (and some of it is horrible) and too much chance of a burning spill.