TEMA 10th Ed. API 660 GPSA Ch. 8

Reboiler Type:

Kettle Reboiler Thermosiphon Forced Circulation

Kettle: Shell-side boiling with enlarged shell. Best for clean fluids, moderate duties, and amine/glycol regeneration.

Process Fluid

Fluid Type Auto-fills latent heat and density for common fluids

Liquid Flow Rate

GPM

Boiling Temperature

°F

Operating Pressure

psig

Vapor Fraction

Percent of feed vaporized (typical 15-35%)

Latent Heat of Vaporization

BTU/lb

Enter 0 for auto-calculation from fluid type

Liquid Density

lb/ft³

Enter 0 for auto-calculation from fluid type

Heating Medium

Medium Type

Steam Pressure

psig

Condensing steam temperature derived from pressure

Hot Fluid Inlet Temperature

°F

Hot Fluid Outlet Temperature

°F

Design Parameters

Tube OD

inches

Tube Length

Standard: 8, 10, 12, 16, 20 ft

Tube Pitch

inches

Typically 1.25 × tube OD minimum

Tube Layout Triangular: higher tube count. Square: easier cleaning.

Tube Passes

Fouling Factor

hr·ft²·°F/BTU

TEMA: 0.001 (clean) to 0.005 (fouling service)

Design Factor

—

Oversurface factor (1.10–1.25 typical)

Known Duty (Optional)

Known Heat Duty

MMBTU/hr

If provided, skips duty calculation and sizes bundle directly

Typical Overall U Values (BTU/hr·ft²·°F)

Service	Kettle	Thermosiphon
Amine regenerator	100–150	120–180
Glycol regenerator	80–120	100–150
Hydrocarbon (light)	100–200	150–250
Hydrocarbon (heavy)	40–80	60–100
Water (steam heated)	200–400	250–500

Engineering Basis

Heat Transfer Equation:

Q = U × A × LMTD

Where Q = duty (BTU/hr), U = overall coefficient (BTU/hr·ft²·°F), A = area (ft²), LMTD = log mean temperature difference (°F)

Heat Duty (from process):

Q = ṁ × x × λ + ṁ × Cp × ΔT

Latent heat + sensible heat. x = vapor fraction, λ = latent heat, Cp = specific heat.

Critical Heat Flux (Kern):

q_max = 12,000 BTU/hr·ft² (kettle, per GPSA)

LMTD for Condensing Steam: When using condensing steam, the hot-side temperature is constant (saturation temperature at steam pressure). LMTD simplifies to T_steam − T_boil.

Design Margin: TEMA recommends 10–25% oversurface to account for fouling, uncertainties, and turndown requirements.

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Results

Heat Duty

MMBTU/hr

Duty (BTU/hr) -

Duty (kW) -

Latent Component -

Sensible Component -

Heat Transfer

LMTD -

Overall U (Clean) -

Overall U (Design) -

Required Area (Clean) -

Required Area (Design) -

Tube Bundle

Tube Count -

Bundle Diameter -

Shell ID -

Actual Area -

Oversurface -

Heat Flux Check

Avg Heat Flux -

Max Allowable Flux -

% of Max Flux -

Design Guidelines

Kettle Reboiler: Shell diameter typically 1.5–2.0× bundle diameter. Liquid level must cover tube bundle. Max heat flux ~12,000 BTU/hr·ft² per GPSA.

Thermosiphon: Requires sufficient static head (4–15 ft) for natural circulation. Vapor fraction at outlet ≤ 25–35% to avoid dryout.

Forced Circulation: Use when fouling is severe or static head is insufficient. Pump provides circulation independent of boiling.

Reboiler Sizing Calculator

Process Fluid

Heating Medium

Design Parameters

Known Duty (Optional)

Typical Overall U Values (BTU/hr·ft²·°F)

Engineering Basis

📚 Learn the Theory

Results

Heat Transfer

Tube Bundle

Heat Flux Check

Design Guidelines

Related Calculators

Heat Exchanger

Heat Transfer

Fired Heater

Glycol Dehydration