Rotary Dryer Capacity in TPH: Wet Feed, Dry Output and Moisture

A “1 TPH rotary dryer” enquiry is incomplete until it identifies what the tonne-per-hour figure measures: incoming wet material, dried product or another basis. State the material, inlet and target moisture, operating conditions and units before asking for size or price. FEECO's dryer FAQ lists material and process information needed for selection.

Separate feed, product and evaporated water

Wet feed contains both solids and water. Drying reduces water content; it does not mean the discharged product has zero moisture. Define moisture as wet basis or dry basis, because these percentages use different denominators.

Wet-basis moisture is water mass divided by total wet material mass. In the simplified balance below, dry solids remain in the product, there are no solids losses and no other material changes.

Engineering insight: a transparent 1 TPH example

Assume 1,000 kg/h wet feed, 40% inlet moisture wet basis and 10% outlet moisture wet basis:

• Dry solids: 1,000 × (1 − 0.40) = 600 kg/h.
• Product flow: 600 ÷ (1 − 0.10) = 666.7 kg/h.
• Water removed: 1,000 − 666.7 = 333.3 kg/h.

Under the same simplified assumptions, producing 1,000 kg/h finished product instead would require 1,500 kg/h wet feed, with 500 kg/h water removal. These are different duties despite both being described casually as “1 TPH.”

This is a mass balance, not dryer sizing, heat consumption or an OP performance guarantee. Material testing and thermal/process assessment are still needed.

Buyer resource: dryer capacity enquiry sheet

• Material, particle sizes, bulk density and representative moisture data.
• Required feed/product rate, normal/peak conditions and tonne definition.
• Inlet and target moisture, stating wet or dry basis.
• Product-temperature limits, available heat source and operating schedule.
• Site layout, dust/exhaust requirements and process hazards for assessment.
• Dryer, feeding, discharge, drive, controls and auxiliary-equipment scope.

Frequently asked questions

Can TPD be converted directly to TPH?

Only when operating hours and the same measurement basis are known. Divide daily tonnes by operating hours—not automatically by 24.

Is one rated TPH valid for every biomass material?

No. The material and moisture duty need separate review.

Does this calculation determine dryer dimensions?

No. It defines one part of the process duty; it does not determine heat transfer, residence time or equipment size.

Request a duty-based quotation

Explore our rotary dryer services and biomass rotary dryer page. Send a completed duty sheet through the contact page for technical review.