Export mango drying — Ghana commercial design scenario
Building capacity to a buyer’s specification.
A commercial mango drying line for Ghana, engineered backwards from an export buyer’s written specification rather than forwards from available capacity. A burner at the upper end of the 200,000–900,000 kcal/h range feeds a multi-chamber plant built for consistency at volume.
A commercial operation, not a cooperative, with correspondingly different constraints: overwhelming seasonal volume depressing prices, quality inconsistency closing off premium markets, unreliable power, and processing capacity that cannot absorb peak harvest.
The configuration
- High-capacity biomass burner at the upper end of the 200,000–900,000 kcal/h range, sized for commercial throughput.
- Multi-tunnel configuration for high daily volume.
- Standards-based quality management built into the production protocol from the outset.
- Hygienic pre-processing infrastructure — washing, sorting, cutting and inspection.
- Comprehensive staff development across operations, maintenance and quality.
Projected outcomes (modelled design targets)
- Substantial annual processing throughput.
- Tight batch-to-batch consistency in final moisture content.
- Access to premium European and Middle-Eastern buyers.
- Significant permanent and seasonal employment created.
- Year-round revenue from stored product rather than a compressed selling window.
What this scenario is
A costed design we are ready to build, not a delivered project. GreenMach has one commissioned installation — a cashew shell burner firing a steam boiler at PCCL in The Gambia — and no drying line has been built yet.
The throughput below is an assumption, stated as one. It would be replaced by the buyer’s contracted volume before anything is sized for manufacture.
The line, item by item
| Item | Specification |
|---|---|
| Burner | Upper end of the 200,000–900,000 kcal/h range, sized to contracted volume |
| Hot air generator | Double chamber, three-pass, indirect exchange |
| Chambers | Multi-chamber tunnel configuration at 1,500 kg per standard chamber |
| Pre-processing | Washing, sorting, cutting and inspection, zoned away from the dry side |
| Product contact | SS 304 trays, wagons and wearing decks |
| Control | PLC with recipe management and full cycle data logging |
| Quality systems | Traceability records, in-process sampling ports, deviation alarms |
How the line would be sized
The method is the one set out for Banfora, run against a commercial rather than a cooperative volume. Peak-day intake gives the water to remove, the cycle gives the rate, and the rate divided through the efficiency chain gives the fuel input.
The chain is combustion 0.85 × hot air generator 0.78 × ducting 0.95 × envelope 0.97 × exhaust 0.68, which multiplies to 0.415 and is carried at 0.40 for sizing. Published in full because most suppliers quote the first term alone and let it be read as system efficiency.
The sequence matters more here than the arithmetic. Building capacity and then looking for buyers is the standard failure mode in this sector. Establishing what buyers specify — moisture, colour, piece size, residue limits, documentation — and engineering to it is what makes the capacity saleable at all.
What we would need to confirm on site
Four things, and the first of them is not an engineering question.
- The buyer’s written specification. Final moisture, colour, piece geometry, sulphite limits and documentation. Everything downstream is designed to it, so a verbal specification is not enough.
- Contracted volume and season. Peak-day intake, not annual tonnage. A line sized on the average turns fruit away in the weeks that matter.
- Fuel supply. Shell, or a residue mix. Whichever it is, the collection arrangement is scoped alongside the equipment rather than assumed to exist.
- Power and water. Supply to the panel terminals and one water connection are the buyer’s, and both are on the critical path more often than the equipment is.
Modelled design targets, not measured results
These are modelled design targets for this configuration, not measured results — we have not yet built this line.
Frequently asked questions
Why design to a buyer specification before sizing the plant?
Because the specification decides the equipment. A buyer wanting 12 % final moisture and a specific piece size sets the cycle, the loading density and therefore the chamber count. Sizing first and asking the buyer afterwards produces a line that runs well and makes something nobody has agreed to purchase.
What does export-grade actually require beyond drying well?
Traceability and evidence. Cycle data logged per batch, in-process sampling, deviation alarms, and a documented cleaning regime between products. Sulphite residue must be declared above 10 mg/kg for the European market, which is a pre-treatment decision rather than a dryer one.
Can a commercial line run below capacity out of season?
Yes, and it should be planned for. Chambers run individually, so a six-chamber plant works as a two-chamber plant out of season without heating empty volume. Recipes anywhere in the 40 to 100 °C range are held per chamber. What it costs is a full wet clean when the product changes, which is most of a shift.
Scaling for export?
We engineer to buyer specification first, then size the plant to match.
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