Fired Heater

Introduction

The fired heater model solves exclusively in dynamics mode. For steady state cases, use the refinery furnace unit operation.

The model takes an air fuel mixture which is combusted to provide a source of heat. Various process streams can then be heated in radiative, convective or economizer zones.

Parameters

The burner feed should contain the air/fuel mixture to be combusted. Combustion requires the presence of H2O, CO, CO2, O2 and CH4 in the component list. Most hydrocarbons can be consumed. Do not use a mixture of say pure propane and oxygen, as it will burn too hot and result in likely flash failure. Add some nitrogen or inert components to the mixture.

The burner can also be turned on or off.

Sizing

The model calculates heat transfer areas and volumes, and for that, sizing information needs to be provided.

Heat Transfer

Heat transfer coefficients, emissivities, and tube metal properties need to be provided. Reference flows should be provided to enhance the model under low flow startup or shutdown conditions.

Performance

These pages show detailed performance views for the furnace, such as temperature profiles.

Specifications

Similar to other unit operations, it is recommended that the furnace be set to not use any pressure drop specifications, but be set to use pressure flow k values. This applies to the tube side as well as the shell side. k values can be easily calculated by providing a pressure drop value, and pressing Calculate Ks.

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