Airflow is key | Grain rides on bed of air to allow maximum circulation
BRANDON — A new continuous flow horizontal dryer designed for low temperature with high airflow reduces energy costs and fire risks.
The Double Flow, built by the Alvan Blanch company in England, can take canola from 25 percent moisture down to nine percent in a single pass at 85 C.
Sunflowers at 20 percent moisture can be taken down to nine percent in a single pass at 70 C.
Feed grains typically run at 100 C to 110 C with the same dry down data, according to Nick Gaisford, who had travelled from the United Kingdom to represent Alvan Blanch at Manitoba Ag Days held in Brandon Jan. 17-19.
“The grain travels on two stationary louvered beds set on an incline,” said Gaisford.
“Grain is loaded on the top bed at the front of the dryer. It runs down the incline to the far end, where it drops to the lower bed. The grain layer is inverted as it drops. Grain then runs down the second incline and returns to the front to be augered out.
“Regardless of what you’re drying, you only need a single pass because you adjust the depth of the grain layer, the speed it travels, temperature at the burner and volume of air.”
Gaisford said grain with higher moisture content runs at a lower speed, higher temperature and thinner layer than grain with less moisture.
A hand crank at ground level adjusts the thickness of the layer. For lightweight seeds like flax, the air volume can be turned down.
Slots in the louvers are aimed down the slope to help gravity move the grain and prevent it from compacting.
“The grain basically floats down the two inclines on a bed of air, allowing maximum air circulation and drying. It’s never compacted. Always loose,” he said.
A chain and slat system, in which the chain speed can be automatically adjusted, pulls the top of the grain layer.
Grain is moved by airflow and slats, so there’s no chance for hot spots to occur, said Gaisford. The inclined beds do not move and are not adjustable. Grain travels over them.
Cooling is not a problem, according to Gaisford. Halfway down the lower bed, fresh outside air is pulled into the lower chamber by a 20 horsepower cold air fan. As it’s directed up through the louvers, the fresh air cools the grain.
This fresh air is recovered and channelled to the burners. Heat removed at the cooling section is channelled up to the main drying compartment to reduce fuel consumption.
The fresh air is regulated by opening or closing the sliding doors along the bottom edges of the dryer. All fans are located inside the dryer housing to reduce noise.
“The entire dryer is an airtight unit. It sits on a concrete footing or a concrete pad with a seal. We control all air entering and exiting the housing. And we direct where the air goes within the housing.
“One of the benefits is removal of dust and chaff at the far end where grain drops to the lower bed. The exhaust airflow lifts the lighter weight dust and chaff and blows it out into a collection box. There’s no need for an expensive cyclone system.”
He said removal of dust and light chaff further reduces the risk of fire.
The automated control system allows unsupervised operation. Safety sensors monitor for an empty feed hopper, blocked discharge, overheating of the furnace or grain, motor overload and burner malfunction. The automated phased failsafe system ensures the correct shutdown procedure is followed.
Another sensor detects if there is a change in moisture levels in the grain flow. It automatically adjusts the speed of the electric motor driving the chain and slat mechanism. Data from this motor is also used in calculating the volume of grain dried over any specific time period.
Two automatic pressure jet burners in the combustion chamber work together so the drying temperature is always correct throughout the full range, without changing nozzles.
Gaisford said the Double Flow is suited to temperamental crops such as malting barley and seed grain that can be damaged by excess heat.
The most popular Double Flow for on-farm use is the DF2200, a 1,000 bushel unit, capable of removing five points of moisture from 1,000 bushels of grain in one hour. In warm dry weather, it can also remove up to two points of moisture without burners.
The Canadian contact is Larry Dorig with Dave Ross Equipment in Spirit River, Alta. The DF2200 sells for $214,000.
For more information contact Dorig at 780-864-3731 or visit www.alvanblanch.com.