Drying systems for tree nuts and oilseeds
The oil is what you are selling. Protect it.
Drying tree nuts and oilseeds removes moisture without damaging the oil fraction that carries most of the crop’s value. Biomass hot air chambers run these crops within the 40–100 °C range at 2.0–3.0 m/s, indirectly heated so no combustion product reaches the kernel, on burners rated 200,000 to 900,000 kcal/h.
Why oilseeds are their own drying problem
Oil-bearing crops fail differently from fruit. Excess heat oxidises the oil and drives free fatty acid up, which is measured, priced and rejected on. Too little heat leaves moisture that supports mould and, in groundnut and maize-adjacent crops, aflatoxin. The working window between those two failures is narrower than for most fruit, and it is the reason controlled drying pays for itself faster here than almost anywhere else.
The second problem is throughput timing. Nuts and oilseeds arrive in a concentrated harvest and then have to be stabilised quickly, before field heat and surface moisture do their work. Chamber capacity, not chamber temperature, is usually the binding constraint.
Cashew shell: the crop that fuels the plant
Cashew is the one crop in this family that supplies its own energy. The shell left after kernel extraction carries 4,800 kcal/kg and 15–25 % CNSL, and a burner engineered around that acidic, phenolic fraction turns a disposal cost into the plant’s fuel supply. Processors drying their own kernels on their own shell close the loop entirely.
Crops in this family
| Crop | Drying temperature | Target moisture | Notes |
|---|---|---|---|
| Cashew kernel | 40–100 °C chamber range | Product specific | Shell is the fuel — 4,800 kcal/kg, 15–25 % CNSL |
| Shea kernel | 40–100 °C chamber range | Product specific | Moisture control protects butter yield and colour |
| Groundnut | 40–100 °C chamber range | Product specific | Shell briquettes at 4,500 kcal/kg — a validated fuel |
| Palm kernel | 40–100 °C chamber range | Product specific | High oil content; surface temperature matters more than air temperature |
| Olive | 40–100 °C chamber range | Product specific | Low-temperature staging protects the oil profile |
| Soybean | 40–100 °C chamber range | Product specific | Balances anti-nutritional reduction against protein preservation |
The equipment behind these crops
- biomass hot air generator
- industrial tunnel dryers
- multi-fuel biomass burner
- turnkey biomass drying plant
Detailed pages by crop and country
Frequently asked questions
What drying temperature should I use for oilseeds?
Lower than for fruit, and staged rather than flat. Our chambers hold anywhere in the 40–100 °C range, and oil-bearing crops usually sit at the bottom of it, because free fatty acid rises with heat history rather than with peak temperature alone. The exact profile is set against your crop, your incoming moisture and your buyer’s specification.
Can one chamber handle several oilseeds?
Yes, on PLC recipes set per crop, provided the changeover is planned. The constraints are hygienic and commercial rather than thermal: residual oil and aroma carry between crops, and an allergen such as groundnut needs a documented cleaning protocol — on SS304 trays and wagons — before a non-allergen crop follows it.
Does cashew shell really cover the fuel demand?
For a cashew processor drying its own kernels, usually yes, and often with shell to spare. Shell carries 4,800 kcal/kg. The practical constraint is not calorific value but storage and handling — shell must stay dry, because rain leaches CNSL and destroys the delivered heat value.
Size a line for your crop
Tell us the product, the daily fresh throughput and the fuel you can source. An engineer replies within one business day.
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