Charcoal

Now for the stupid question of the day - do charcoal bbq briquettes offer a viable alternative to coal for live steam or do they not burn hot enough or the right heat.

Not all of us in Australia have ready access to coal.

I've only ever used gas powered boilers and was just wondering.

Wood charcoal (from Bunnings hardware) burns OK in my 6" traction engine but produces a lot of sparks and needs an arrestor on the chimney. I have been burnt on more than one occasion. Easily raises steam but does not last long and continually adding a handful size every 5 minutes of operation.

Have not used briquettes that much because the type which I used produced a lot of clinker. Have not tried a mix of charcoal and briquettes which may be a better option.

Coal is available but has to be bought in bulk quantities and many clubs buy by the tone and share it between members.

Edited By Paul Lousick on 28/08/2023 09:21:32

Yes, but it depends on what sort of wood was used to make the charcoal. How much ash, water, air, and volatile chemicals are in the wood. Not much heat in Balsa charcoal because Balsa is so light. Other woods have a high volatile and ash content, so a lot of heat is lost when the wood is cooked evaporating oils and acetone etc, leaving a Carbon diluted by ash.

The wood used to make Charcoal for Gunpowder comes from a few high carbon low ash species. The wood used to make BBQ charcoal is highly variable, but as a rule of thumb hardwood charcoal contains more energy per lump than softwood charcoal.

You will need to sample several brands to find experimentally which works best in your loco. And don't assume that a particular brand will always be consistent - there's no guarantee the maker will carbonise exactly the same species of wood every time: more likely he carbonises a mix decided by the availability and cost of wood. Choosing woods that flavour food are more important to him than heat value: the needs of locomotive drivers aren't considered at all. But the right sort of charcoal competes well with good coal.

Most coals are unsuitable for model locos too. Coal is a natural product created over millions of years. It's qualities depend on the type of vegetation, high or low ash content etc, that grew in a primeval forest then on the circumstances in which it was submerged, how much pressure was applied to it by succeeding geological layers, and for how long. Brown coal is very poor, whilst hard coals have a high heat value. Welsh Steam Coal was the best in the world for locomotives. It was a hard coal, created from a low ash vegetation, highly compressed, for a very long time - as good as it gets. Other coals, notably from the Eastern US, are nearly as good, but most are more contaminated. or have lower heat value than the very best. Coal suitable for making coke is a good bet if you can find any, but most of it goes for steel-making. Power stations burn inferior coal, where high ash content and impurities like Sulphur and Phosphorous can be managed. Older Brits will remember 'Nutty Slack', a dusty highly contaminated coal product left after removing the best lumps. It burnt reluctantly in domestic grates and the pollution caused smog - anyone with a lung or heart problem died young! Now we have Smokeless Fuel, coal treated to remove dirt, not quite coke. I don't know if it's any good for model locos.

Not sure what the problem obtaining coal in Australia is : Australians consume more coal per head than any other country in the world! Most likely reason is it's all exported, mostly to China, and there isn't a domestic market.

Dave

As well as considerably lower density than coal, charcoal generally lacks volatiles, and thus has a much shorter flame length. These factors will reduce its performance in a boiler designed for coal.

Edited By Clive Brown 1 on 28/08/2023 09:48:55

Was Anthracite not "the good stuff" for model steam

As Nick originally stated, it is difficult to get coal in small quantities for model engines, even though Australia has vast quantities. Fortunately, I also belong to a full size steam engine club that gets it by a 20 ton truck load.

Nick, this the type of charcoal that I have used which is made from hard wood but at almost $60 for a 20 kg bag is expensive and I would burn 2 of these on a full days steaming.

Edited By Paul Lousick on 28/08/2023 10:15:03