Biomass hot air for tea withering and coffee drying
Withering is a controlled loss, not a dry-down.
A biomass hot air generator supplies tea withering troughs and coffee drying beds with clean, filtered air at a controlled temperature, heated indirectly so no combustion product reaches the leaf or the bean. Units deliver 2,500–3,000 m³/h at 50–150 °C, fired on pellets, briquettes or crop residue.
Indicative price of a biomass hot air generator, 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.
Withering versus drying
Withering is not drying, and treating it as drying is the most common way a tea line loses quality. The object is a controlled, partial moisture loss that makes the leaf physically pliable and starts the biochemical changes the rest of the process depends on. Take too much moisture out and the leaf will not roll; take it out too fast and the chemistry does not develop evenly through the bed.
Coffee drying is a genuine dry-down, but a slow and even one. Driving it hard produces a bean dry at the surface and wet at the centre — the same case-hardening failure that afflicts high-sugar fruit, with a cup-quality consequence instead of a shelf-life one.
Temperature and airflow requirements
Both processes are airflow-led rather than temperature-led. Withering troughs need a large volume of gently warmed air moving evenly through a deep bed of leaf, and the risk of pushing temperature up is scorching the leaf against the trough floor while the top of the bed is barely affected. Coffee beds have the same uniformity problem in a different geometry.
This is why volume-control dampers and even distribution matter more here than peak output. A generator delivering 2,500–3,000 m³/h into a well-balanced duct network does more for a withering trough than a hotter one into an unbalanced one.
Specifications
| Parameter | Value |
|---|---|
| Matched burner | 200,000–900,000 kcal/h |
| Generator airflow | 2,500–3,000 m³/h per generator |
| Delivered air temperature | 50–150 °C, controlled |
| Heat transfer | Indirect, double chamber, three-pass |
| Filtration | MERV-8 |
| Ducting | 3 mm MS, 80 mm rockwool insulation, volume-control dampers |
| Fuels | Wood pellets, biomass pellets, 90 × 90 mm briquettes, crop residue |
| Control | Delta PLC with recipe management |
| Warranty | 12 months from date of shipment |
| Lead time | 10–18 weeks from confirmed order and receipt of advance payment |
This page covers the equipment. For the crop side — process parameters, fermentation and smoke taint — see the tea, coffee and cocoa drying hub. For the underlying generator see the biomass hot air generator, and for the fuel stage the biomass pellet burner. The nearest sibling duty is agricultural processing.
Supply outside West Africa
We accept orders from any country. West Africa is the market these systems are engineered around and where most of them go, but there is no territory we will not supply.
Lead time, warranty and scope of supply do not change with the destination: manufacture in 10–18 weeks from confirmed order and receipt of advance payment, warranty 12 months from date of shipment, and spares dispatched alongside the machines. For installation outside the region the buyer covers the team’s travel, accommodation and entry formalities — stated up front because it is a real line in the budget. Documentation and the operator interface are supplied in English and French; other languages on request.
Frequently asked questions
Will biomass firing put smoke into tea or coffee?
Not with indirect heat exchange. Combustion gas passes one side of the exchanger and process air the other, and they never mix, so no smoke phenol reaches the leaf or bean. Smoke taint is a rejection at the fine-flavour end of both markets rather than a price deduction, which is why direct-fired biomass is not offered for this duty. The generator is indirect throughout, moving 2,500 to 3,000 m³/h.
Can one generator serve several withering troughs?
Yes, through a balanced duct network with volume-control dampers on each branch. The constraint is uniformity rather than total output: with 2,500 to 3,000 m³/h available, each trough must receive its designed share, or batches finish at different moisture levels and the line runs to the slowest.
How does this differ from your standard drying chamber?
The generator is the same equipment. What differs is the downstream geometry — troughs and beds rather than tunnel chambers with wagons — and the control profile, which is airflow-led and gentler than a fruit or fish drying cycle. Sizing starts from bed area and depth rather than from the 1,500 kg batch mass a tunnel chamber is quoted at. The burner behind it is the same 200,000 to 900,000 kcal/h platform.
Discuss a tea or coffee installation
Tell us the trough or bed area, the throughput and the withering or drying profile you work to, and we will size the heat stage against it.
Talk to an engineer