Kiln Drying on Crop Drying Floor

[spuddog0507]

41 minutes ago, openspaceman said:

What would be interesting is to put a temperature and RH data logger just under the top layer of logs, one on top of one of the floor vents would be handy too.

The hot air is coming out of the vents on the floor at 86 degrees and it is fairly being blown out, hence i dont think or i would not like to work on that floor when its running. i have spent a bit of time on it and it is only a bit, your feet are piss wet with sweat in no time and you can feel the heat being blown up your trouser legs, 

Last back end they was combining in the rain and tipping wheat on to the floor and spreading it out at about 12" deep and drying it from 28% down to 10% in 12 hrs, they dry a lot of sawdust for other farms in the area and when that comes off the floor that is down to approx 3-5% after 48 hrs and thats sawdust direct from a sawmill so will start at 40% ish, What these floors are designed for they do very well but they are not for designed for drying logs, but they will do it, it just takes a lot longer than other products,

[Will76]

9 hours ago, spuddog0507 said:

Hi are you having to pay for this service or is it for free ?

we have access to same sort of floor, a price is sorted out but we havent used it yet as its not as good as i thought it would be, for drying logs, 

some one else has used it and i have been and robbed a few logs out of a crate and i was very dissapointed at the result, we tested several logs out of several crates and from different positions in the crate, ok not covered up just the heat n draft going through,

The results after 10 days on the floor where, logs from the outside of the crate where down to 8% on the outside but when split 32% on the inside, logs from the centre of the crate 18% on the outside and still at 42% when split, but this guy who the logs belong to is addvertising and selling them as super dry kiln dried logs, i think he might just get 1 or 2 complaints, so if you cover yours the results might be slightly better but i know i need to come up with a different plan for getting my logs dried, i have an idea and i think it will work and i think i could get logs dried down to 15% from fresh cut in 5 days but time will tell,,,,

Thanks - very interesting to hear real world examples.

I would have thought I'd need to cover the IBCs to have any chance of success. I guess it's worth trying to find out.

 

What's your 5 day plan?! Sounds interesting!

 

I think polytunnels in a windy location are the answer here....

 

 

[openspaceman]

The reason for the RH and temperature logger at the top is to see how much of the heat is wasted and  how much unsaturated air is being exhausted.

 

There is a dimensionless term called the Biot number which  describes how a heat gradient applied at the surface will put energy into the middle. It is used for determining how hot a body will get in free space over time. I suspect the biot number for grain and sawdust is much less than one, hence they accept energy easily and that for logs much greater than one, so they don't deliver energy into the middle very well .

[SbTVF]

Just tip as much on the floor as you can loose, as deep as you can and once the top logs are dry the rest is. You don't want to be doing it in IBCs.

 

You can dry logs on a floor kicking out that heat in 7 days.

Some floors more designed towards drying chip at lower temperatures can take 3 weeks or more.

 

The one I've used that dried them in 7 days was with a 1000kw chip boiler powering a Lauber Lenz 650 unit. Serious heat energy and fan power. Those logs were sopping wet Ash and they were as dry as can be after 7 days.

 

 

We use 40yard hook bins with false floors on an AD plant with a slightly smaller Lenz unit and that takes 7-10 days depending on species. Oak and Beech take the longest. Full load of birch might only take 5 days.

 

Get a price per day for the floor to be turned on in terms of pricing it in my opinion.

 

RE data loggers, I've tried this. The bins basically sit at around 55-75° and once the initial surface moisture is off the logs the air is not much more than 5-10% RH

Whereas in my recirculating kiln once the RH reaches 10% the logs are sub 20% moisture but it'll have worked its way down steadily from as much as 80% RH to start with.

Uses a lot less energy but if like us you can use waste heat at an AD plant well then it's better pushed through logs first than out of a big heat sink to cool the turbines.

 

 

[Billhook]

I have three corn stores with Challow wooden fully vented floors which are not being used at the moment as the grain from the farm is taken away by the contractor to dry in his barn.  Having operated these on floor stores for many years I would be surprised if they worked for wood especially wood in crates. I have never done so.  Then there is the massive cost of running the fans (electric) let alone the cost of heating (gas? wood?) which I would have thought would come to more than the value of the wood.  We never used heat ,just ambient air and it could take several weeks in which case you may be better just storing it in a Dutch barn with open sides

When we had a wet harvest, if the corn was too deep ,say over eight feet and you were not too vigilant  there might be a layer of wet corn gradually making its way up and eventually forming a bridge to block air flow.  With oilseed rape we never stored it above  four feet.  Very important to have a relative humidity switch on the fan to prevent blowing wet air through.

Wood chips, perhaps or even densely stacked firewood even more perhaps.

Having said all this I would be interested to hear the result.

[openspaceman]

38 minutes ago, Billhook said:

 

When we had a wet harvest, if the corn was too deep ,say over eight feet and you were not too vigilant  there might be a layer of wet corn gradually making its way up and eventually forming a bridge to block air flow.  With oilseed rape we never stored it above  four feet. 

Good to hear your experience, Do you mean you never used heat when drying grain, just blew when the ambient RH was low?

 

This wet layer migration upward is what I meant when I said  as the moist saturated air from drying the lower layers rose and cooled moisture condensed, as I said with wood chip this layer was visible.

[Billhook]

6 hours ago, openspaceman said:

Good to hear your experience, Do you mean you never used heat when drying grain, just blew when the ambient RH was low?

 

This wet layer migration upward is what I meant when I said  as the moist saturated air from drying the lower layers rose and cooled moisture condensed, as I said with wood chip this layer was visible.

The problem was worse if we had to sell the grain early to make way for more storage.  To do this we used heat in the early days before we had enough  grain store capacity .  When we eventually built enough capacity we were able to dry the grain slowly over the Winter to benefit from higher prices in March/April.

The initial blowing of air after harvest in a wet year would take the grain down from say 24% to 18/19% quite quickly .  (It was very difficult to harvest grain at high moisture content without losses at the combine)  This would prevent the grain from heating up as the cooling effect of the air was just as important as the drying.  Because it was so wet we could keep the fans going even if the relative humidity was high to keep the grain cool.

As it dried to below 18% we had to be careful not to run the fans with humid air so the fans were controlled automatically to hopefully reach the 15% which meant the grain could be safely stored with less worry of heating or pests.

Later on there were vertical auger stirring systems which improved air flow and broke the layer of damp grain.  This would work well with sawdust and woodchip but obviously not with firewood!

You can see how quickly things heat up if you put your hand in a heap of lawn cuttings after a week or two.

Yes I suppose blowing dry air would dry firewood a bit quicker but the cost would be huge and I am not sure it would have much more effect on the inner wood.than just leaving it to dry in the conventional way.

So air coming in at below 70% RH will dry corn down to 15% and oilseed down to *%

 

Bulk Storage Drying of Grain and Oilseeds (HGCA Topic Sheet No.16)

ADLIB.EVERYSITE.CO.UK

 

This is where I have some difficulty with these new rules on firewood moisture content.  I do not sell wood to the public and the only way I can make any sense of firewood production is to use it myself after producing it with my own labour which I thoroughly enjoy (for some bizarre reason!) to save on gas, oil and electric heating.

If I spent all this money to dry wood down to the required percentage  and sold it to someone who stored it outside in a badly ventilated shed, and who lived in a damp hollow, the wood would soon take the moisture out of the air and become damp and the customer might then come back and complain to some inspectorate to fine me

[openspaceman]

4 hours ago, Billhook said:

If I spent all this money to dry wood down to the required percentage  and sold it to someone who stored it outside in a badly ventilated shed, and who lived in a damp hollow, the wood would soon take the moisture out of the air and become damp

Thanks for that again but as long as the shed is rain tight and moisture cannot get into the logs form underneath I d I think the equilibrium moisture content in the UK means it will not uptake water to above 20% wwb.

 

I think the reasoning behind the regulations are that sellers will leave the market and generally less solid fuel will be burned in smaller stoves.

[Billhook]

20 hours ago, openspaceman said:

Thanks for that again but as long as the shed is rain tight and moisture cannot get into the logs form underneath I d I think the equilibrium moisture content in the UK means it will not uptake water to above 20% wwb.

 

I think the reasoning behind the regulations are that sellers will leave the market and generally less solid fuel will be burned in smaller stoves.

Yes you are probably correct but copying these recommendations off the web, I cannot see many UK customers bothering to do all this.  In America it is a way of life and I am sure people show their log piles to each other with a sense of pride

 

To help season wood as fast as possible and to keep firewood dry in the winter, the firewood should be:

• Stacked up with one side of the logs fully exposed to the atmosphere.
• Located under some sort of overhang to provide cover to the wood for the majority of rainfall and snow.
• Placed on a dry and impermeable platform such as concrete, or raised off the ground
•  
• The UK is a damp place in Winter compared to US and Scandinavia where it may be cold and snow a lot but much less rain and fog.
•  
• My only hope for all firewood producers is that it will become so expensive to heat .yourself in the Winter using electricity, since coal and gas and oil will be banned in the name of Climate Change, that firewood again will become valuable and there will be a lot of pressure on the Government to make it easily available especially after a few power cuts have nailed a lot of the elderly and vulnerable.