neqsim-fired-heater-duty-screening

name	neqsim-fired-heater-duty-screening
calculation_basis	screening
version	0.1.0
description	Educational fired-heater duty and radiant-flux screening using public energy-balance relations (API 560 style). USE WHEN: a task needs a public, screening-level estimate of process duty, fired duty, fuel rate, and average radiant flux for a fired heater before detailed thermal design.
last_verified	2026-06-18
requires	{"python_packages":[],"java_packages":[],"env":[],"network":[]}

Fired Heater Duty Screening

Use this skill for public, educational fired-heater screening. It estimates the process duty, the fired duty, the fuel-gas rate, and the average radiant-section heat flux using open energy-balance relations so an agent can scope a fired-heater study and check the radiant flux against a public guideline before detailed thermal design.

When to Use

• When a user asks roughly what fired duty and fuel rate a heater needs.
• When an agent needs a quick radiant-flux check to scope a fired-heater study.
• When examples must run without confidential heater designs, vendor data, or company specs.

Inputs

• mass_flow: process mass flow in kg/s.
• specific_heat: process-fluid specific heat in kJ/(kg K).
• inlet_temperature: process inlet temperature in kelvin.
• outlet_temperature: process outlet temperature in kelvin.
• thermal_efficiency: heater thermal efficiency, default 0.85.
• fuel_heating_value: fuel lower heating value in MJ/kg, default 46.0.
• radiant_area: radiant-section tube surface area in m2.
• allowable_radiant_flux: allowable average radiant flux in kW/m2, default 37.0.

Outputs

• process_duty_kw: process absorbed duty Q.
• fired_duty_kw: fired duty from the efficiency.
• fuel_rate_kg_s: fuel-gas mass rate.
• average_radiant_flux_kw_m2: process duty divided by radiant area.
• flux_ratio: ratio of average radiant flux to the allowable flux.
• fired_heater_warning: ok, watch, or high-flux.
• assumptions: public assumptions used by the placeholder model.

Engineering Method

The Python class FiredHeaterDutyModel uses open energy-balance relations only:

• the process duty uses Q = mass_flow * specific_heat * (T_out - T_in).
• the fired duty uses Q_fired = Q / thermal_efficiency.
• the fuel rate uses fuel = Q_fired / fuel_heating_value.
• the average radiant flux uses Q / radiant_area and is compared to a public guideline.

This is educational and screening-only logic. It uses a constant specific heat, treats all process duty as absorbed in the radiant section for the flux estimate, and does not model convection-section split, tube-wall temperature, flame and bridgewall temperature, draft, or emissions. Typical public average radiant fluxes are about 30 to 37 kW/m2. It is not a replacement for validated fired-heater design (for example API 560) and a qualified review.

Python Usage Pattern

from fired_heater_duty_screening import FiredHeaterDutyModel

model = FiredHeaterDutyModel()
result = model.evaluate(
    mass_flow=15.0,
    specific_heat=2.4,
    inlet_temperature=473.15,
    outlet_temperature=623.15,
    radiant_area=200.0,
)

print(result.fired_heater_warning)
print(result.fired_duty_kw)
print(result.average_radiant_flux_kw_m2)

Related NeqSim Functionality

For validated fired-heater calculations, redirect to existing NeqSim classes:

• neqsim.process.equipment.heatexchanger.FiredHeater — fired-heater equipment model with duty and efficiency.
• neqsim.process.equipment.heatexchanger.Heater — generic process heater with duty calculation.
• neqsim.process.equipment.powergeneration.HRSG — heat-recovery steam generator for waste-heat duty.

This skill is a public energy-balance triage layer that decides when to invoke those validated heater classes.

Validation Checklist

• Mass flow, specific heat, and temperatures are positive and T_out > T_in.
• Radiant area and efficiency are positive and in range.
• Tests cover a duty calculation, a high-flux case, and invalid input.
• Results are described as educational screening indicators.
• Real design is redirected to validated methods, API 560, NeqSim, and qualified review.

Common Mistakes

Symptom	Cause	Fix
Duty too low	Specific heat at wrong temperature	Use an average specific heat over the duty range
Flux always high	All duty assigned to radiant section	Split convection and radiant duty in detailed design
Fuel rate wrong	Higher heating value used with efficiency on lower basis	Keep the heating value and efficiency on the same basis

Limitations

• No proprietary heater designs, vendor data, or company specs are included.
• No convection-section split, tube-wall, draft, or emissions modeling is performed.
• A constant specific heat is assumed over the full duty range.

References

• NeqSim repository: https://github.com/equinor/neqsim
• NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md