How many Kwh of heat to dry grain

Just doing some rough calculations for grain drying using biomass.

I have seen somewhere its x kwh / ton / 1% of MC reduction but cant recall where

I know there are huge variables like fan speeds / air flows / depth etc but a ball park may be helpful.

TYIA
 

Exfarmer

Member
Location
Bury St Edmunds
I am not an expert, but I do not think there is a simple answer.
It is a matter of reducing the R/H of the incoming air.
The lower this is the quicker the grain moisture reduces.
Also you cannot the grain moisture below certain points if the R/H is too high.
So basically the more heat you put in the quicker the grain moisture will come down
 
I am not an expert, but I do not think there is a simple answer.
It is a matter of reducing the R/H of the incoming air.
The lower this is the quicker the grain moisture reduces.
Also you cannot the grain moisture below certain points if the R/H is too high.
So basically the more heat you put in the quicker the grain moisture will come down
yup I agree entirely to all points. I am sure there is a formula though to work it out under 'ideal conditions' (what ever that means!)
 

PeterW

New Member
Does this help?

Balring Farm, Mintlaw (courtesy of Hamish Watson) Hamish grows 283ha (700ac) of combinable crops (2,100t) and installed a 100t tray drier with stirrers in 2007 (previously had 2 mobile driers). The tray drier was supplied from Clark & Sutherland and cost approx £60,000 which included the shed.

The tray drier used two burners fuelled by gas oil, normally operating at 55oC with an electric fan blowing the hot air through the grain. A full tray (100t wet grain) would take 12hrs of drying (20% mc grain dried to 14%mc) plus a further 3hrs of cooling. Depending on the grain’s moisture content it would normally take 1,000l of gas oil to dry 100t of grain (10,000kWh, 1L diesel = 10kWh). The annual cost to dry the combinable crops was £14,700 and rising annually.

The economics Previously to dry 100t of grain would take 1,000l gas oil @70p = £700 or £7/t Using biomass, 100t grain would require 2.5t wood @ £ 50 = £125 or £ 1.25/t A saving of £ 5.75/t or £ 12,075 per year for the farm (2,100t) If eligible for RHI, can earn £7,711 for drying the grain which is index linked for 20-years Effectively the crops are dried for free, plus £ 5,086 surplus.

Balring Farm, Mintlaw (cont) Assumptions:
• Dry 2,100t pa using the biomass burner.
• Throughput of the tray drier 100t in 18hrs = operating for 378hrs
• 378hrs @ 400kw = 151,200 kWh
• 151,200 kWh @ 5.1p (tier 1) = £7,711

Without RHI, pay-back of the £34,000 capital cost would be 3-years from the savings in fuel cost. With RHI, pay-back is less than 2-years plus crop drying in the future is free.

Regards

PeterW
 

T C

Member
Location
Nr Kelso
Does this help?

Balring Farm, Mintlaw (courtesy of Hamish Watson) Hamish grows 283ha (700ac) of combinable crops (2,100t) and installed a 100t tray drier with stirrers in 2007 (previously had 2 mobile driers). The tray drier was supplied from Clark & Sutherland and cost approx £60,000 which included the shed.

The tray drier used two burners fuelled by gas oil, normally operating at 55oC with an electric fan blowing the hot air through the grain. A full tray (100t wet grain) would take 12hrs of drying (20% mc grain dried to 14%mc) plus a further 3hrs of cooling. Depending on the grain’s moisture content it would normally take 1,000l of gas oil to dry 100t of grain (10,000kWh, 1L diesel = 10kWh). The annual cost to dry the combinable crops was £14,700 and rising annually.

The economics Previously to dry 100t of grain would take 1,000l gas oil @70p = £700 or £7/t Using biomass, 100t grain would require 2.5t wood @ £ 50 = £125 or £ 1.25/t A saving of £ 5.75/t or £ 12,075 per year for the farm (2,100t) If eligible for RHI, can earn £7,711 for drying the grain which is index linked for 20-years Effectively the crops are dried for free, plus £ 5,086 surplus.

Balring Farm, Mintlaw (cont) Assumptions:
• Dry 2,100t pa using the biomass burner.
• Throughput of the tray drier 100t in 18hrs = operating for 378hrs
• 378hrs @ 400kw = 151,200 kWh
• 151,200 kWh @ 5.1p (tier 1) = £7,711

Without RHI, pay-back of the £34,000 capital cost would be 3-years from the savings in fuel cost. With RHI, pay-back is less than 2-years plus crop drying in the future is free.

Regards

PeterW
Using today's prices, kero at 45p and wood chips at 110 per tonne makes biomass hard to justify.
 

PeterW

New Member
But with a good RHI tariff you get more back in payments than the wood chip costs you? Then it's just a matter of financing the boilers to match our existing fuel costs, once paid for, you're drying for free.
 

scotston

Member
from Richard Flach , Flach and Leroy; 200t of grain will require 20,000 cfm airflow. To reduce the relative humidity by 35% to 65% (equivalent to 14.3%mc) will require 90kw heat. No stirrers, constant humidity drying.
 

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