Fired Heater Sizing Calculator

Calculation Mode:

Size from Process Duty Fuel Calc (Known Duty)

Calculate heat duty from process fluid conditions, then size radiant and convection sections.

Process Fluid

Fluid Type

Flow Rate

Inlet Temperature

°F

Outlet Temperature

°F

Operating Pressure

psig

Fluid Specific Gravity

air/water=1

Specific Heat (Cp)

BTU/lb-°F

Leave 0 for auto-estimate based on fluid type

Known Heat Duty

Absorbed Duty

MMBTU/hr

Process Outlet Temperature

°F

Used for tube wall temperature estimate

Heater Design

Heater Type

Tube OD

inches

Tube Wall Thickness

inches

Sch 40: 0.337" for 4.5" OD

Tube Material

Design Factor

Typical: 1.10–1.25 over process duty

Fuel & Combustion

Fuel Heating Value (HHV)

BTU/SCF

Fuel Heating Value (LHV)

BTU/SCF

Excess Air

Typical: 15-25% for natural draft, 10-15% for forced draft

Ambient Temperature

°F

Learn the Theory

Radiant heat transfer, convection design, tube metallurgy, API 560 standards, and efficiency optimization

Read Engineering Guide

Engineering Basis

Process Duty

Q = ṁ × Cp × (T_out − T_in)

Tube Wall Temperature (API 530)

T_wall = T_fluid + q × (1/h_i + t/k)

API 560 API 530 GPSA Ch. 8

Fired Heater Quick Reference

Radiant fraction65–75%

Max flux (gas)10,000 BTU/hr-ft²

Gross efficiency80–92%

Excess air15–25%

Stack temp350–500°F

Frequently Asked Questions

What does the fired heater sizing calculator determine?

It calculates radiant and convection section sizing, tube wall temperature, fuel consumption, and thermal efficiency for fired heaters.

What standards does this fired heater calculator use?

The calculator follows API 560 and API 530 standards for fired heater design.

Can this calculator be used for gas processing applications?

Yes, it is designed for fired heater sizing in gas processing and refining applications.

Process Fluid

Known Heat Duty

Heater Design

Fuel & Combustion

Learn the Theory

Engineering Basis

Results

Fired Heater Quick Reference

Frequently Asked Questions

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