(735bj) Fired Heater Modeling Using Htri

A fired heater is the industry's largest energy consumer and NOx / CO2 emitters process. Furnace models are useful for troubleshooting plant problems, evaluating proposed changes to revamp old heaters for a new service, evaluating the addition of an economizer/air pre-heater to improve plant energy efficiency, evaluating the effect of proposed changes in plant operating conditions on furnace operation, estimating retirement life of tubes based on past and projected operations, and assist in assessing vendor furnace designs. This paper shows a stepwise modeling of a fired heater using HTRI software. The rigorous model utilizes four furnace components:

• Combustion module:
  • Any fuel type(s) (liquid, gas)
  • Any oxidant stream (e.g., air, turbine exhaust)
  • Specify %XS air or O2% in stack
• Radiant coil module (API 530 method):
  • Tube thickness, radial temp profiles, tube life, heat flux (circumferential)
• Convection section module:
  • Duty, flue gas, and metal temperatures calculated
  • Draft profiles
• Radiant section module:
  • 3-D Hottel Zone method for radiation heat transfer calculations
  • Integrated rigorous process side calculations (mass, heat, momentum transport)
  • Multiple burners modeled as superimposed individual jet flows