Biomass hot air generators for industrial drying
What turns a flame into a usable process.
A biomass hot air generator transfers heat from a biomass burner into a clean air stream through a heat exchanger, so combustion gases never touch the product being dried. SahelDry units are double-chamber, three-pass designs delivering 2,500–3,000 m³/h of filtered air at a controlled 50–150 °C, fired on pellets, briquettes or loose crop residue.
Indicative price, Ex-Works (EXW): USD 3,140–14,135
Shipping, customs clearance and local duties are extra. The final price depends on the configuration and is fixed in the written quotation.
This is process equipment for drying a product to a target moisture content. If what you need is to heat a building rather than dry a product, here is the difference.
Where this equipment is used
The same equipment is specified across several product classes. These are the ones it is configured for most often:
industrial mango drying system, fish and seafood drying and fruit and vegetable drying.
Each of those pages carries the drying parameters, cycle times and quality targets for that product class.
How indirect heat exchange works
Combustion gases from the burner pass through one side of a heat exchanger. Process air passes over the other side, picks up heat, and is ducted to the drying chambers. The two streams never mix. This is what makes the system usable for food: no smoke, no ash, no CNSL-derived compounds and no combustion odour reach the product.
Three passes mean the combustion gas crosses the exchanger three times before it is exhausted, recovering heat that a single-pass design sends up the stack. The double chamber allows the second stage to hold temperature while the first responds to load changes, which is what keeps the delivered air within a narrow band rather than swinging with the fire.
Specifications
| Parameter | Value |
|---|---|
| Airflow | 2,500–3,000 m³/h |
| Delivered air temperature | 50–150 °C, controlled |
| Configuration | Double chamber, three-pass |
| Heat transfer | Indirect, air-to-air heat exchanger |
| Heat-transfer efficiency | above 80 % |
| Static pressure | 250 Pa |
| Blowers | 2 × 15 HP, dynamically balanced, 2,800 rpm |
| Matched burner range | 200,000–900,000 kcal/h |
| Filtration | MERV-8 |
| Ducting | 3 mm MS, 80 mm rockwool insulation, volume-control dampers |
| Control | Delta PLC with multiple monitoring points, closed-loop fuel and air trim |
| Warranty | 12 months from date of shipment |
| Manufacturing lead time | 10–18 weeks from confirmed order and receipt of advance payment |
| Design life | 15–20 years, main structure |
Which fuels it runs on
The generator is fired by a matched multi-fuel biomass burner, so fuel flexibility is set at the burner, not here. Fuels the burner is designed for:
| Fuel | Calorific value | Form |
|---|---|---|
| Cashew shell | 4,800 kcal/kg | Loose shell |
| Groundnut shell | 4,500 kcal/kg | Briquette, 90 × 90 mm |
| Dried mango peel | 4,200 kcal/kg | Briquette, 90 × 90 mm |
| Corn cob | 4,100 kcal/kg | Briquette, 90 × 90 mm |
| Cotton stalk | 3,900 kcal/kg | Briquette, 90 × 90 mm |
| Rice stalk | 3,800 kcal/kg | Briquette, 90 × 90 mm |
Wood pellets and commercial biomass pellets are also accepted — see the biomass pellet burner page for pellet-specific feed and ash handling.
Air distribution and filtration
- MS ducting — 3 mm mild steel, leak-proof welded joints, fabricated to SMACNA standard, two coats of anti-rust paint.
- Thermal insulation — 80 mm rockwool at 65 ± 3 kg/m³, chicken-wire mesh and 24G aluminium cladding, fire-rated Class 1 to BS 476 Part 6:1989.
- Volume-control dampers — 3 mm MS, opposed-blade, on fire-rated bushes, for precise flow balancing to each branch.
- MERV-8 filtration — 610 × 610 mm panels at the blower inlet, capturing particles from 3.0 to 10.0 microns.
Where it is used
A hot air generator is the heat stage of a complete drying line. It feeds:
- Industrial tunnel dryers — 1,500 kg per chamber, continuous or batch.
- Panel room drying — six insulated rooms, 4,968 kg fresh mango per line batch.
- Batch units — smaller volumes and rapid product changeover.
Typical applications include industrial mango drying systems, fish and seafood drying, fruit and vegetable dehydration, bakery oven and rusk drying, snack frying and edible oil heating, papad drying, tea withering and coffee drying, and spice roasting and grain puffing.
Configure for your process
Sizing a generator for your line
Sizing runs from the product, not the equipment. To specify a unit we need:
- 01Product and daily throughput — fresh input in kg/day, not finished output.
- 02Target moisture — starting and finishing, wet basis.
- 03Available fuel — type, form, moisture content and reliability of supply.
- 04Site conditions — ambient temperature and humidity range, altitude, power supply.
- 05Existing equipment — whether the generator feeds new chambers or retrofits existing ones.
We publish real specifications and real limitations. Where a system will not suit an application, we say so.
One system has been commissioned so far: a 900,000 kcal/h cashew shell burner firing a steam boiler at Premium Cashew Commodities Limited in The Gambia, on the factory’s own empty shell. It is a boiler application — no drying line has been built anywhere yet, so every drying figure on this site remains an engineered design target. The configuration is published in full, and the measured performance deliberately is not, on the page for the PCCL installation in The Gambia.
Frequently asked questions
What is the difference between a direct-fired and an indirect hot air generator?
In a direct-fired system, combustion gases mix with the process air and pass over the product. In an indirect system the two streams are separated by a heat exchanger. Indirect costs more and loses some efficiency to the exchanger, but it is the only option where the air contacts food, because combustion products, ash and fuel-derived compounds never reach the product. Our generators are indirect throughout, double chamber and three-pass, delivering 2,500 to 3,000 m³/h.
What temperature range can it hold?
50–150 °C at the generator outlet, controlled by a Delta PLC that trims fuel feed and combustion air together. Delivered temperature at the chamber is set by the process: mango dries at 65–70 °C, fish at 45–50 °C, and industrial materials run higher.
Can it run on wood pellets rather than crop residue?
Yes. The matched burner accepts wood pellets, commercial biomass pellets, 90 × 90 mm agricultural briquettes and loose cashew shell. Changing fuel changes feed rate, ash volume and cleaning interval, so the fuel should be named at the sizing stage rather than after commissioning.
How much airflow do I need?
Airflow is set by chamber volume and the air velocity the product tolerates — typically 2.0–3.0 m/s across the product bed. A single 2,500–3,000 m³/h generator suits a line in the region of one to two 1,500 kg tunnel chambers; larger plants use multiple units or a larger custom build.
What maintenance does it need?
Daily visual checks, weekly mechanical and control routines, and monthly servicing of major components. The two disciplines that determine service life are ash removal on schedule and heat-exchanger cleaning — a fouled exchanger loses efficiency before it shows any fault. The main structure is designed for 15 to 20 years; the grills are consumable and are expected to be replaced.
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Pairs directly with our industrial tunnel dryers and batch units, or integrates into existing process-heat installations.
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