Biomass Briquettes for fuel vs coal

[bkueber]

I was hoping some of our european members could comment. I am considering the Idea of building a hydraulic briquette mill to produce hardwood sawdust briquettes to burn in my boiler and perhaps market to the us live steam community.

The questions I have are:

How well do briquettes burn in our boilers?

How do they compare to wood and coal?

What is the cost in Europe for a 20 and 50 lb bag?

Is the smoke good smelling and clean?

What are the pros/cons to using them?


Thanks!

[Gudmund]

I tried wood briquettes and found that with the boiler 'quiet' they were very good, but as soon as the blower was started the briquettes 'disintegrated', the burning wood chips flew up the chimney and burned holes in the canopy. I have heard others have tried, but haven't heard of anyone finding them successful.

Gudmund

[gondolier88]

Hi Bkueber,

We have been using compressed sawdust logs on SY Gondola for three years now, the ones we use, after trialling a few different makes, are 'Blazer Logs', manufactured by Clifford Jones Timber Ltd. in Wales, UK.

I will answer your questions in the order you ask them;

How well do briquettes burn in our boilers?

Very well is the answer- though they require a lot more top air to the grate, far less bottom air and we also need a flue damper to increase the dwell time of the flue gasses in the tubes of our loco' type boiler.

How do they compare to wood and coal?

They don't have the same calorific value of coal so you burn more by weight for the same energy output, but they are higher output than split wood.

They do take quite a while to catch properly, especially under heavy draft conditions, and this means recovering a dead fire is very hard, you HAVE to keep a deep bed on the grate.

What is the cost in Europe for a 20 and 50 lb bag?

Hard to answer as we buy in bulk to the tune of 70tons per summer season, but commercial price per ton is usually around the £370-390 mark.

Is the smoke good smelling and clean?

Respectively; 'a definite no' and 'sometimes', it depends on what woods the logs have been made out of, but in our experience what smoke there is is very dense, and foul smelling.

What are the pros/cons to using them?

Pro's;

-Cheaper than coal
-Vastly more environmentally freindly
-Easy to store
-Vastly reduced ash- we ash out every 4/5 days as opposed to having a full ashpan every day on coal
-What ash is made is potash and wholly re-usable as fertilizer

Con's;

-Hard to fire with a nonchalent mentality- you WILL end up with no fire on the grate- and to relight you MUST have flames, glowing embers will very quickly disappear.
-Easy to store- but it has to be a completely waterproof purpose built store- they expand to 200% their original volume when wet!!!
-They don't smell as nice
-Require modified grates/flues
-No good on vertical boilers, especially watertube- the dwell time of the products of combustion would be far too quick, and their radiant heat properties don't compare to fossil fuels.

Greg

[steamboatjack]

I have tried "blazers" too, great if you have a big space above the fire bars, and I agree will all that Gudmund & Greg say,
However..... If you have a small open boat, and it rains you can expect to have a big mess on your hands unless you keep them dry, not always possible on a small boat.
regards
Jack

[mtnman]

Is the smoke good smelling and clean?

Some of us think coal smoke smells fine! It reminds me of the steam traction engine I used to have. I plan on only burning soft coal in my launch. Here in East Tennessee coal is only $70 a ton, that's a LOT of days on the lake!

[bkueber]

Oh, I like the smell of coal smoke (provided it is low sulfur), just not the waxy smell of presto logs.

[daysaver1]

At every NWSS annual meet I've attended the sawdust logs have been made available for free and each year the bin ends up empty. Yes, I take them too and burn them in my Semple 40' vft boiler and have had very positive results. Would I buy them to burn in my boat? No, I have plenty of good smelling wood available and as was mentioned, when wet they make a heck of a mess.

[SL Ethel]

It sounds like there are two different kinds of sawdust logs people are discussing, and there are important differences. "Presto-Logs" and other similar products are generally sawdust bound together with parafin wax. On the other hand, wood pellets (the 1/4" diameter ones used in pellet stoves) are bound together by the natural resins in the wood which get sticky under the high heat and pressure of the pelletizing process.

If you put straight sawdust into a briquetting machine, it likely won't hold together enough to make it into the boiler in one piece. You would need some kind of binder like wax to hold things together. The benefit, however, is getting large briquettes or logs. The little wood pellets from pellet mills burn fine, but they require a modified grate and would work much better with an automatic stoker or hopper.

Cheers,
Scott

[gondolier88]

It sounds like there are two different kinds of sawdust logs people are discussing, and there are important differences. "Presto-Logs" and other similar products are generally sawdust bound together with parafin wax. On the other hand, wood pellets (the 1/4" diameter ones used in pellet stoves) are bound together by the natural resins in the wood which get sticky under the high heat and pressure of the pelletizing process.

If you put straight sawdust into a briquetting machine, it likely won't hold together enough to make it into the boiler in one piece. You would need some kind of binder like wax to hold things together. The benefit, however, is getting large briquettes or logs. The little wood pellets from pellet mills burn fine, but they require a modified grate and would work much better with an automatic stoker or hopper.

Cheers,
Scott

Hi Scott,

Blazer Logs, the ones we burn on SY Gondola are not held together by anything other than the naturally occuring resins; the majority of others on the market are the same as they all use the same machine to make them.

Anything with wax in I would view more as a firelighter than as a fuel.

Greg

[daysaver1]

I've been told that at least in the Western part of the US that no sawdust logs are made with any sorts of binder any more. It's all done with natural occuring pitch and LOTS of pressure...say like 40+ tons.