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Calcimator

Evaporator Design Calculator

Design a single-effect evaporator: calculate evaporation rate, steam requirements, heat duty, and required heat transfer area.

Inputs

kg/hr
mass fraction
mass fraction
psi
°F
kW/(m²·°C)

Results

Evaporation Rate

4,000 kg/hr

Steam Required

4,000 kg/hr

Heat Duty9,040,000 kJ/hr
Required Heat Transfer Area167,028.5 m²
Steam Economy1 kg/kg
How to Use This Calculator
  1. Enter the Feed Rate in kg/hr, the Feed Concentration, and the Product Concentration as mass fractions — these define the evaporation duty.
  2. Enter the Steam Pressure in kPa supplying the evaporator heating side.
  3. Enter the Boiling Point Elevation in °C due to dissolved solids — reduces the effective temperature driving force.
  4. Enter the Overall Heat Transfer Coefficient (U) in kW/(m²·°C) — typical range 1–5 kW/(m²·°C) for aqueous solutions.
  5. Read the Evaporation Rate and Steam Required in kg/hr to size utilities, and the Required Heat Transfer Area in m² for vessel specification.
  6. Check the Steam Economy (kg evaporated per kg steam) — values near 1.0 are typical for single-effect; multiple-effect designs achieve 2–5.

How the result changes with Feed Rate

Feed RateEvaporation RateSteam Required
10,0018,000.8 kg/hr8,000.8 kg/hr
35,00128,000.8 kg/hr28,000.8 kg/hr
65,00052,000 kg/hr52,000 kg/hr
90,00072,000 kg/hr72,000 kg/hr

What each input means

Feed Rate
Mass flow rate of the dilute feed solution.
Feed Concentration
Mass fraction of solute in the feed (e.g., 0.1 = 10% solids).
Product Concentration
Desired mass fraction of solute in the concentrated product.
Steam Pressure
Pressure of the heating steam supplied to the evaporator.
Boiling Point Elevation
Increase in boiling point due to dissolved solids compared to pure water.
Overall Heat Transfer Coefficient
Overall U-value for the evaporator. Typical range: 1-5 kW/(m²·°C).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Feed Rate = 5000, Feed Concentration = 0.1, Product Concentration = 0.5, Steam Pressure = 200 = 6 input(s) provided
  2. Calculate Evaporation Rate
    Evaporation Rate
    4000 = 4000
  3. Calculate Steam Required
    Steam Required
    4000 = 4000
  4. Calculate Heat Duty
    Heat Duty
    9040000 = 9040000
  5. Calculate Required Heat Transfer Area
    Required Heat Transfer Area
    167028.5 = 167028.5

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