Drying corn on aerated floor anyone?

kevindb880

Member
Location
Herts
We have a grain store with aerated floor which is blown by two Typhoon fans, its only been used to cool wheat but this year we want to put wheat in it with 16 or17% moisture and attempt to dry it.
we have no heaters so the question is what is the best way regarding heaters etc?
The wheat is usually pushed up about 10ft high!
 

Badshot

Member
Location
Kent
First question.
How big is the floor?
How big are the fans kw/hp?
Is it a complete drying floor, or well spaced laterals?
I can dry from 20%, 60 by 100, 2 X 40hp fans and temperature/humidity controls.
With the aid of a butler
 

chaffcutter

Moderator
Arable Farmer
Location
S. Staffs
If you haven’t got auto control to run the fans when the Relative Humidity is right to dry, you need to get a meter so that you can switch them on and off at the right time. If you blow when the air is too dry you will just overdry the grain at the bottom and the moisture can condense out in the top layers and make a wet crust on the top.
If you blow at the right RH it will dry fine.
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
If you haven’t got auto control to run the fans when the Relative Humidity is right to dry, you need to get a meter so that you can switch them on and off at the right time. If you blow when the air is too dry you will just overdry the grain at the bottom and the moisture can condense out in the top layers and make a wet crust on the top.
If you blow at the right RH it will dry fine.
Whatever you do it will always dry at the point the air goes in, and form a drying front. The optimum way to do is to dry as much as you think, then give it a good stir (2 or 3 days) without blowing, then sample for moisture,
DO NOT dry whilst stirring - this puts the dry grain above the wet stuff, where it will re-absorb the moisture and you will achieve nothing.
 

Lincsman

Member
Arable Farmer
Location
Lincolnshire
If you haven’t got auto control to run the fans when the Relative Humidity is right to dry, you need to get a meter so that you can switch them on and off at the right time. If you blow when the air is too dry you will just overdry the grain at the bottom and the moisture can condense out in the top layers and make a wet crust on the top.
If you blow at the right RH it will dry fine.
You only make the top wetter when using heat, the air cools as it rises through the heap and drops the water, enough ambient air at 60% RH will dry anything, its a question of fan power and time before days are over 60%

Stirring helps as it keeps the heap loose, pushing it up with blades is also a bad idea due to compaction.

PS dont stop the fan if its over 19%... even in fog.
 
Last edited:

teslacoils

Member
Arable Farmer
Location
Lincolnshire
As said, fan power is what you need at depth. I've merrily shoved it ten foot deep in sheds with big fans and humidity controllers at 20 percent and let the expensive kit sort it out.
 
We have a grain store with aerated floor which is blown by two Typhoon fans, its only been used to cool wheat but this year we want to put wheat in it with 16 or17% moisture and attempt to dry it.
we have no heaters so the question is what is the best way regarding heaters etc?
The wheat is usually pushed up about 10ft high!

Got 3 sheds with your system. One from the 60’s with a typhoon fan. Simplest way to get heat into that is by putting a mobile burner in front of the fan intake. We’ve just got an old gas one. The fan sucks the heat in from the burner. It’s not the fastest but it’ll do 800t of wheat from 20% down to 15% in 4 weeks.

The newer ones have heat from a heat exchanger along the same lines sat in front of the fan so it sucks the heat from it into the tunnel.

However in both cases the key is stirring. The older shed has a fixed stirrer which you must run all the time. In the newer sheds we just use a mobile stirrer. If you don’t stir you’ll get a crust on the top although you can alleviate that by having a large fan pulling the air out of the shed as it’ll draw the damp air out stopping it hanging around.
 
A fortnight from now and the window for drying using ambient air will be slipping away, as the days shorten and the nights cool down.

Ideally you need a heat source (as above) and good ventilation pushing warm (drier) air up through the grain and pulling cool (damp) air out of the eaves of the shed.

Check the airflow volumes with a meter on your grids and keep taking moisture samples at depth as the drying front makes progress.
 
Buy a modulating gas burner and run 24 hours per day it’s is the most cost effective drying
the heat will only be used for less than half the day

i find the rh I’d low enough from 1030am to 11pm to dry corn with out heat
but the saving with a modulating gas burner is that blowing 24 hours per day in august and September when it is warmer removes for moisture than in November when it is cooler saving on electric

air at 20 c and 60 rh caries a lot more moisture than air at 60 rh and 10 degrees
 
We also stir like this if you want to be quick and it’s not to deep. This will stir 1000t at 2m deep in about 30 mins. It’s a 13t machine but an 8t would be better due to being physically smaller in the shed.
 

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Brisel

Member
NFFN Member
Location
Midlands
DO NOT dry whilst stirring - this puts the dry grain above the wet stuff, where it will re-absorb the moisture and you will achieve nothing.
I disagree. Re wetting grain takes a lot of moisture and time. How do you think a full set of grain stirrers on a gantry work? You have to think of it becoming a batch drier with dry air going in and wet air coming out, not just in terms of a drying front in an unmoved heap.
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
I disagree. Re wetting grain takes a lot of moisture and time. How do you think a full set of grain stirrers on a gantry work? You have to think of it becoming a batch drier with dry air going in and wet air coming out, not just in terms of a drying front in an unmoved heap.
Sorry, I have spent a long time studying drying, and have written a thesis on control of drying. If you stir while drying, you will heat up the heap first before drying, and spend a lot of energy doing so. You will eventually dry the grain, but in the least efficient way possible. Then you will have to cool it down. Since doing my PhD 20 years ago, we have been drying the way I recommend, and it works with least cost.
 

shakerator

Member
Location
LINCS
Sorry, I have spent a long time studying drying, and have written a thesis on control of drying. If you stir while drying, you will heat up the heap first before drying, and spend a lot of energy doing so. You will eventually dry the grain, but in the least efficient way possible. Then you will have to cool it down. Since doing my PhD 20 years ago, we have been drying the way I recommend, and it works with least cost.
Surely every case varies with the parameters of air flow , depth, heat, extraction, frequency of stirring ——-many many permutations ? I would like to see your thesis as always keen to learn !
 

Brisel

Member
NFFN Member
Location
Midlands
Sorry, I have spent a long time studying drying, and have written a thesis on control of drying. If you stir while drying, you will heat up the heap first before drying, and spend a lot of energy doing so. You will eventually dry the grain, but in the least efficient way possible. Then you will have to cool it down. Since doing my PhD 20 years ago, we have been drying the way I recommend, and it works with least cost.
So, how do stirrers work? Plenty of these systems about. I can see that they prevent crusting and you certainly use a lot of heat. Are they just less efficient because of the heat input, extra cost of the stirrers and disturbance of the drying front?

Are they just a way of drying wetter grain at greater depth?
 

fudge

Member
Arable Farmer
Location
Lincolnshire.
We have a grain store with aerated floor which is blown by two Typhoon fans, its only been used to cool wheat but this year we want to put wheat in it with 16 or17% moisture and attempt to dry it.
we have no heaters so the question is what is the best way regarding heaters etc?
The wheat is usually pushed up about 10ft high!
Just wondering what type of wheat you are storing and for how long? We have an on floor drying system with a constant humidity controller and I don’t find drying feed wheat below 16% economic. If cooled properly it will definitely store for at least six months at that mc and the deductions incurred at the feed mills our grain goes to wouldn’t cover the cost of drying. Depends on end user of course.
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
So, how do stirrers work? Plenty of these systems about. I can see that they prevent crusting and you certainly use a lot of heat. Are they just less efficient because of the heat input, extra cost of the stirrers and disturbance of the drying front?

Are they just a way of drying wetter grain at greater depth?
Stirrers are essential for deep grain. Our strategy is:
1. Fill store and stir for a day or so. This mixes the grain and removes any compaction from grain pushers, etc. so you get uniform air passage.
2. Estimate how long it will take to take out the moisture in the grain. Stop stirrers and dry for that time, or slightly less with stirrers off.
3. Give it a day or two stirring with air off, then measure moisture. If still too high, repeat 2 and 3 until done.
If you omit the stirring in stage 3, you will end up with over dried grain on the bottom if you are using heated air, or in a low humidity ambient condition.
For best effect, study a psychrometric chart and the equilibrium moisture table of your grain.
1628432293823.png

1628432416910.png
 

Brisel

Member
NFFN Member
Location
Midlands
Thank you. Every day is a school day in here 👍

What wisdom can you share when it comes to blowing moist air through a bulk? My education (not a PhD) taught me that 20% or over needs blowing 24/7 regardless of humidity, without adding heat.
 

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Man fined £300 for bonfire-related waste offences

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Written by William Kellett from Agriland

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A man has pleaded guilty at Newtownards Magistrates’ Court to waste offences relating to a bonfire next to the electrical sub-station on the Circular Road in Newtownards, Co. Down.

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Discussion with Northern Ireland Environment Agency (NIEA) officers confirmed the site...
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