SVPro

Grain drying

The challenge

Drying grain and cereal crops to controlled conditions efficiently, effectively, and without taint, shrinkage or degradation.

The solution

From small scale minimally powered installations, to integration with existing systems, SVPro Grain solutions are cost effective, efficient and effective.

Smarter grain drying, for better returns

"The primary advantage of high-temperature drying is that you can harvest grain at any moisture, dry it quickly, and sell it soon after harvest without moisture discounts." - Wheat and barley drying (UoM Extension)

"Well designed - purpose built high flow rate aeration drying silos with air flow rates of 15-20 l/s/t and higher, can dry grain from higher moisture contents... over several days and sometimes weeks depending on starting grain moisture and ambient conditions. For aeration drying, larger fans and ducts are required... a large quantity of ambient air with low to moderate RH (relative humidity) is utilized to push drying fronts through grain. For most inland grain growing regions, fans should run for most of the day and night apart from short periods of high RH." - DPI Qld

"Moisture content of 25 % is not uncommon in newly harvested grain in humid areas but it must be dried immediately to protect it against mould. At 14 % moisture grain can be safely stored for 2 to 3 months. For longer periods... moisture content must be reduced to 13 % or below". - Solar Drying (Weiss)

Drying and aerating stored grain: sizing a SVPro system

Aeration is the practice of moving air through stored grain to reduce the rate of grain deterioration and prevent storage losses. Spoilage in stored grain is caused by mould growth and insect activity, which is related to the moisture content and temperature of the stored grain. Aeration greatly improves the "storability" of grain by maintaining uniform temperature throughout the storage: reducing mould development and insect activity, and preventing moisture migration.

There are two aeration approaches: cooling, and drying. The cooling of grain through aeration requires airflow rates of only 7-14m3/h/tonne. As air passes through the grain it collects moisture and creates a drying front, which must be forced through the volume of grain to attain drying.

Only in very dry climates with consistently low relative humidity and little risk of airborne moisture is this possible. In most areas, dehumidified and dry air is suggested, and considered best practice.

To dry grain with aeration, airflow rates should ideally be no less than 50m3/h/tonne, and preferably more than 70m3/h/tonne. Snap drying rates can be as high as 120m3/h/tonne.

source: WA guide to high moisture harvesting (CBH group)

System design is based on a number of factors, including the amount of moisture to be removed, the timeframe, and the volume of grain to be dried. To ascertain preliminary system sizing, calculate the desired moisture reduction, and consequent weight reduction, for a given quantity of grain. For example:

wheat, from harvest 16.0% to finished 12.5%, 10000kg: finished weight 9600kg

Around 0.7kWh of energy is required to remove each litre of moisture. For this example, that equates to 280 kWh. To dry over 16 days requires 17.5kWh/day.

Average solar insolation levels in Australia vary by season, and in wheat-belt areas often between 2-8kWh/m2/day. We’ll assume 3kWh/m2/day, which implies a collection area of 5.8m2.

A single SVPro module has a collection area of approximately 2m2, so three modules will be required. Fans with a volume and back-pressure rating suited to the rates of drying and method of storage must then be selected, and ducting incorporated. Additional options include temperature and humidity controllers, zone monitors, flow control and check valves, each of which must be matched to the system.