M.03Dryer Evaporation and Heat Load

Set up the mass and heat balance for preliminary dryer sizing.

Typically 0.8–1.2 kJ/kg·K for minerals and salts.

Covers exhaust air and shell losses; typically 40–70% for convective dryers.

Results

Water evaporated
—
Product rate
—
Dry solids
—
Net heat duty
—
Gross heat duty
—
Specific heat consumption
—

    This tool is for preliminary sizing. Final design must be verified with material tests, the relevant standards and equipment manufacturer data.

    Formulas

    Dry solids
    S = F · (1 − x₁)
    Product
    P = S / (1 − x₂) W = F − P
    Evaporation heat
    Q_w = W · [cp_water · (100 − T₁) + h_fg]
    Heating
    Q_s = S · cp_s · (T₂ − T₁) + (P − S) · cp_water · (T₂ − T₁)
    Gross heat
    Q_gross = (Q_w + Q_s) / η

    How to use

    Net heat is the theoretical energy needed to evaporate the water and heat the product to its outlet temperature. Heat lost with exhaust air and through the shell is approximated with the thermal efficiency; the gross value is a starting point for burner or heat exchanger selection.

    We used calculations like these in the preliminary design of projects such as the Eti Maden Kırka borax pentahydrate and Yatağan lump coal drying plants.

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