The Morrin Climax boiler has a central vertical drum surrounded by many inclined, bent water-tube loops. Each loop returns to the same drum at a higher connection. A fire chamber surrounds the lower drum. This page illustrates that historical arrangement and provides a simplified evaporation heat balance.
Climax Boiler Interactive Calculator
Adjust effective evaporating area, absorbed flux, heat-rate setting and latent heat. Compare the evaporation heat balance while exploring the central drum and inclined tube loops.
Equation Used
- Area is effective evaporating surface; representative tube drawings do not count actual tubes.
- Input heat flux is absorbed flux, not fuel input or a boiling-limit rating.
- Liquid enters this simplified energy balance at saturation.
- Pressure, circulation velocity, heat losses, feedwater heating and superheating are not solved.
This is the Morrin Climax vertical water-tube arrangement, not a reconstruction of a Climax logging locomotive boiler. The heat balance uses absorbed heat available for evaporation of saturated liquid. It excludes feedwater heating, superheat and additional losses. Effective flux is a calculated input quantity, not a safe-flux limit.
The central drum and inclined tube loops
Hiscox illustrates the Climax with a central water-and-steam drum and inclined bent tubes. Kennedy describes both tube ends expanded into that drum at different heights. Water passes from the drum into the heated loops and the less-dense heated mixture returns through the higher ends. The annular fire chamber heats the tubes around the lower drum.
The cutaway removes part of the casing and shows a representative subset of loops. The upper drum provides steam space. Some historical arrangements also included upper drying or superheating chambers and a feedwater-heating coil; these are omitted from the evaporation-only drawing and calculation.
The Morrin Climax arrangement
The Morrin Climax is a vertical water-tube generator with loops connected to one central drum. The illustration follows the arrangement described by Hiscox and Kennedy. It does not identify the boiler construction of a Climax logging locomotive.
Evaporation heat balance
Q = A × q × F/100; steam rate = Q/hfg.
A is evaporating area in ft², q is absorbed heat flux at the full setting in Btu/(h·ft²), F is the selected percentage, and hfg is latent heat in Btu/lb. The resulting rate is lb/h; multiplying by 0.45359237 converts it to kg/h.
This assumes saturated liquid receives only its latent heat of evaporation. For actual feedwater and outlet conditions, use Q/(h_out − h_in). Fuel input also requires a heat-transfer efficiency or loss balance. No critical heat flux, pressure rating or tube-wall temperature is determined.
Worked heat-balance example
At 180 ft², 12,000 Btu/(h·ft²) full-setting absorbed flux and an 80% setting, the effective flux is 9,600 Btu/(h·ft²). Absorbed heat is 1,728,000 Btu/h, or 1.728 MMBtu/h.
With an entered latent heat of 838 Btu/lb, the evaporation estimate is 1,728,000/838 = 2,062.1 lb/h, approximately 935.3 kg/h. These are illustrative inputs, not an operating recommendation or a rating for an identified boiler.
Interpreting the controls
Doubling area or absorbed flux doubles the estimated evaporation rate. Doubling the heat-rate setting has the same effect when the assumed flux relationship remains linear. A larger latent heat reduces mass evaporation for the same absorbed heat. The animation markers show flow direction; they do not measure circulation velocity or steam quality.
Questions about the Climax calculation
Why do both tube ends join one drum?
That is the defining connection shown in the historical Climax references. The return end is higher than the lower entry.
Does the calculator predict fuel consumption?
No. The flux input represents absorbed heat, so fuel heating value and losses would be needed for a fuel-rate calculation.
Is the maximum slider value a safe operating limit?
No. The range is a calculator input range. Safe operating conditions depend on the specific pressure equipment and its engineering assessment.
Why does latent heat change the output but not the drawn tubes?
It changes the energy required per unit mass of evaporated water. It does not specify a tube dimension or a measured circulation rate.
References & Further Reading
- G. D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, printed page 61, figures 193–194.
- Rankin Kennedy, Modern Engines and Power Generators, volume VI, printed pages 93–95, figures 96–98.
- Spirax Sarco, Heat Transfer, heat and enthalpy-of-evaporation principles.
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