Forage dehydrators, how to calculate your ventilation system

Guide to calculating ventilation systems for forage dehydrators

Proper ventilation system design in a forage dehydrator is crucial to ensuring process efficiency and the quality of the final product. In this guide by Casals Ventilación, we show you how to perform the necessary calculations to determine the type and number of fans required.

CASE STUDY: drying 10 Tonnes of forage per hour

1. Initial parameters:

• Drying capacity: 10 tonnes/hour.
• Initial moisture content: 65%.
• Final moisture content: 12%.
• Air temperature: 250°C.
• Dryer type: Rotary.

2. Calculating the amount of water to remove:

The goal is to reduce the moisture content from 65% to 12%.

• Initial water content: 10 tonnes × 0.65 = 6.5 tonnes.
• Final water content: 10 tonnes × 0.12 = 1.2 tonnes.
• Water to remove: 6.5 tonnes - 1.2 tonnes = 5.3 tonnes/hour.

3. Calculating hot air flow rate:

To remove 1 tonne of water, approximately 4,000 m³ of hot air at 250°C is required.

• Total air flow: 5.3 tonnes × 4,000 m³/tonne = 21,200 m³/hour.

4. Fan selection:

For this airflow, a medium-pressure centrifugal fan with a capacity of 21,200 m³/hour and a pressure of 2,500 Pa is recommended, ensuring the system's resistance is overcome.

Recommended fan:

• MTRU 710: A high-efficiency centrifugal fan designed to withstand high temperatures and optimise the drying process.

5. Energy consumption calculation:

• Effective power: 20.29 kW.

• Hourly energy consumption: 20.29 kWh.

  Download the full guide for more details

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