Small scale batch grain dryers

Comparing small scale drying options

Download the complete publication PDF from ADMI: Small Scale Batch Dryers for Developing and Underdeveloped Countries

Open-air sun drying

Capacity: limited by space

Drying time: depends on weather conditions, 2 to 5 days

Crops: any

Fuel: solar

Portable? not applicable

Performance considerations: grain needs to be shifted periodically to improve drying.

Bubble dryer

Capacity: 500 or 1,000 kg

Drying time: Reducing moisture by .5 percent every hour for rice or corn in good conditions. With optimal conditions, a crop can be brought from 22 to 14 percent moisture in 6 to 8 hours, according to the manufacturer.

Crops: tested for rice and maize

Fuel: solar or electric options available

Portable? yes, can be rolled up and transported easily

Ease of construction: professional

Product available for purchase? Yes, from GrainPro at the link below.

Performance considerations: grain should be mixed regularly for optimum drying.

An instructional setup video is available here.

See FAQ from the International Rice Research Institute (IRRI) for more information.

Bin dryer

Circular bin dryers ventilate the grain outwards from a center column. They are compact, save floor space, and can be expanded or contracted to accommodate different batch sizes.

STR bin dryer

Capacity: 500 kg and up, bin can be expanded to more than 500 kg

Drying time: 500 kg of paddy dried from 24.75% to 8.5% moisture content in 7.5 hours. Time can depend on air temperature and blower speed.

Crops: rice, maize

Fuel: Electricity needed for blower, heat generated by burning rice briquettes or LP gas

Portable? yes, can be disassembled and transported

Ease of construction: some technical expertise required

Directions available for download? yes

Performance considerations: grain should be mixed regularly for optimum drying

Flat bed dryer

In the flatbed dryers, grain is laid out on a perforated screen, and dried by forcing heated air from below. A fan provides the drying air. A furnace provides drying heat. Loading and unloading the bed is done manually. Multiple versions of the flat bed dryer have been developed for use by smallholders.

Vietnamese flatbed dryer

This classic simple flatbed dryer was developed in Vietnam. It can be constructed in 4-ton (SGH4) or 8-ton (SGH8) configurations.

Capacity: 4 or 8 tons per batch depending on configuration

Crops: paddy, maize

Drying time: reduce moisture by about 1.5% per hour; 4 ton batch of paddy dried from 25% to 15% in 9-11 hours

Fuel: generator or electricity connection for fan and additional biomass furnace for heat

Performance considerations: grain needs to be mixed by hand; cover over the dryer allows use in more weather conditions.

Portable? no

Ease of construction: no technical expertise required

Directions available for download? Yes

SRA flat bed dryer

This dryer is an incremental upgrade to a conventional unidirectional flow flatbed dryer by introducing the principle of airflow-reversal drying. The reversible air dryer adds a cover to a standard flatbed dryer and an air channel to allow the operator to force air from the top down or from the bottom up. By reversing the airflow, these dryers reduce the moisture differential between the topmost and bottommost layers of grain, thereby increasing the consistency in drying.

Capacity: 500 kg up to 12 tons

Drying time: reduce moisture by about 1.15% per hour; an 8-ton batch of paddy can be dried from 24% to 12.5% moisture content in 9-11 hours.

Crops: paddy, whole coffee, coffee bean, pulped coffee, peanuts

Fuel: generator or electricity connection for fan and additional biomass furnace for heat

Portable? no

Performance considerations: Due to reverse flow drying, grain does not need to be mixed.

Collapsible flatbed dryer

The Easydry M500 dryer is a small collapsible flatbed dryer designed to be portable, unlike the conventional flatbed. In addition to portability, it differs from the conventional flatbed dryer by using a heat exchanger after the blower, so that clean air is blown through the grains to be dried.

Capacity: 500 or 1,000 kg

Drying time: for 500 kg, the dryer can reduce moisture by about 1.6% per hour; a batch of maize can be dried from 17% to 13% moisture content in 2.5 hours.

Crops: paddy, whole coffee, coffee bean, pulped coffee, peanuts

Fuel: generator or electricity connection for fan and additional biomass furnace for heat

Portable? yes

Performance considerations: Grain needs to be mixed frequently.

Ease of construction: technical expertise required

Directions available for download: yes

Flatbed drying wagon

The Flatbed Wagon Dryer is a completely self-contained mobile flatbed dryer, which is commercially available. This dryer can be shipped into a standard 20-foot shipping container anywhere in the world. It is designed for precision drying and contains a thermo-humidistat, which regulates the heater to bring the product to the desired moisture content..

Capacity: 215 bushels and 315 bushels

Drying time: reduce moisture by about 1.67% per hour; the 215 bushel dryer takes about 3 hours per 5% moisture reduction.

Crops: maize, but steel mesh can be customized to accommodate finer grains including flaxseed, rice, and wheat

Fuel: electricity

Portable? yes

Ease of construction: professional production required

Performance considerations: No grain mixing necessary. Difficult to use in poor electricity supply situations. Sides are 9 feet high, which could make loading difficult.