The Yarrow arrangement has an upper steam drum and two lower water drums connected by inclined water tubes. Explore the three-drum layout and a simple steam-output estimate from fuel rate and an evaporation ratio you supply.
Yarrow Water Tube Boiler Interactive Calculator
Enter fuel rate and an assumed steam-to-fuel mass ratio to estimate steam output. The displayed drum pressure repeats your pressure input; it is not a predicted pressure.
Equation Used
- Inputs are user-supplied scenario values.
- The displayed equations are evaluated directly.
- Entered efficiencies, shares, limits and factors are not predicted.
- The visual is schematic and not dimensional.
- Strength, fatigue, wear, variation, controls and safety compliance are omitted unless explicitly calculated.
How the Yarrow Water Tube Boiler Works
The inclined water-tube banks connect the lower drums to the upper drum around the furnace. The schematic illustrates their arrangement; the calculator does not solve circulation or combustion.
What This Calculator Represents
Evaporation ratio is an input, not a predicted boiler efficiency. The fixed conversion factors do not account for actual feedwater or steam enthalpy. Pressure does not change the computed steam output. Circulation, combustion, strength and operating limits are not calculated.
Calculation Method
Steam output = fuel rate × entered evaporation ratio. Using steam output in lb/h, boiler horsepower = steam output / 34.5 and heat-to-steam indicator = steam output × 970.3 / 1,000,000 in million Btu/h. These conversions use fixed equivalent-evaporation reference values. Drum pressure is the entered pressure.
How to Read the Result
Change one input at a time to compare its effect. Apply the assumptions stated beside the equations when interpreting each result.
Assumptions and Limits
Evaporation ratio is an input, not a predicted boiler efficiency. The fixed conversion factors do not account for actual feedwater or steam enthalpy. Pressure does not change the computed steam output. Circulation, combustion, strength and operating limits are not calculated.
Frequently Asked Questions
Does changing the pressure input change predicted steam production?
No. This simple calculation multiplies fuel rate by the entered evaporation ratio. Pressure is displayed for reference and is not used to solve heat transfer or steam properties.
What does the evaporation ratio mean?
It is the assumed mass of steam produced per unit mass of fuel. The calculator multiplies your fuel rate by this entered ratio; it does not predict the ratio from combustion or heat transfer.
Is the drawing suitable for manufacturing?
No. It is a schematic explanation and does not specify manufacturing dimensions, tolerances or materials.
Do these results establish safe operating limits?
No. Assess the complete equipment, loads, materials, controls and applicable requirements separately.
References
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