CFD Modeling of Industrial Burners

Introduction to Industrial Burners

  • Basic of combustion is discussed in the previous post what are essential parts of gas burners.
  • An industrial burner is a piece of mechanical equipment connected to a furnace or combustion chamber  to assist the combustion process by correctly mixing air and fuel with designed velocity and using an ignition source
  •  Major parts of the burner
    • air and fuel metering system
    • ignition source
    • Burner tiles
    • air register: damper opening mechanism
    • Fuel tips and pipe
Principle of Industrial Burners_and its parts
  • Wall-fired premix burner mounted on the fired heater wall is shown below


  • High-pressure fuel is injected in the Centre of the venturi cone to entrain more air for combustion

Gas Burner - Venturi effect uded for mixing of fuels

  • The mixture of air and fuel is ignited to form a flame. The following figure shows an example of venturi burner.


  • The mounting of the gas-fired burner on the fired heater is shown below

 Coal Fired Burner

  • In power generation, most of the power is generated by coal-fired thermal power plant
  • Coals are easily available at low cost in many countries
  • The combustion process of a coal-fired boiler is more complex compared to gas-fired boiler due to turbulence, multiphase flow, ash handling, and pollution
  • To understand such complex combustion and waste heat absorption, CFD modeling can be used to design and select the best configurations of burner and boiler furnace

  • The pulverized coal-fired boiler is shown below. Burners can be wall-fired or corner-fired.



Schematic of Coal-fired Burner

  • In a coal burner, coal particles are spread in the Centre of of burner surrounded by air

  • Air staging carried out for low NOx
  • The air-jet type low NOx burner of Babcock Wilcox is shown below. Air staging is carreid out to control combustion.

Cement Kiln Burner

  • Cement kilns are used for the pyro-processing stage of the manufacture of Portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium
  • A burner is used to heat the cement mixture. Different types of burners have been used in cement industries
  • Due to the high-temperature gradient across the cement kiln, thermal stress results in the failure of the shell of the cement kiln
  • Major issues is the selection of low NOx burners and overheating of cement kiln
  • CFD modeling will help to design a low NO burner and configuration of air cooling

Cement Kilns: Design features of rotary kilns

  • A typical Cement kiln Burner is shown below. It can be gas-fired or coal fired.


Oil burner

  • Oil burners are also used in some cases when fuel gas is not available
  • Oil burners need the mechanics of fuel automation for spreading liquid droplets, evaporation  and mixing with air

Scope of CFD Simulation

  • Objective: CFD simulation is carried out for industrial burners to understand the following results:
    1. Velocity contours
    2. Mixing Flow Pattern of fuel and air
    3. Flame Pattern
    4. NOx
  • The following three industrial burners are considered for CFD modeling
    1. Premix (Inspiration Mix) burner
      • Type pf fuel: Natural Gas
      • Firing rate: 0.3 MM Btu/hr
      • A simple heater model considered to check burner design
    2. Coal-Fired Burners in Boiler
      • Type pf fuel: Coal
      • Firing rate: 800 MW
      • waste recovery units like super heater, economizers,s and air pre-heater
    3. Cement Kiln burners :
      • Type pf fuel: Natural Gas
      • Firing rate: 3.7 MM Btu/hr
      • Air jets used for cooling of heated cement kiln
  • Pre-mix burners have been mounted vertically in the fired heater
  • The maximum capacity of the Venturi  burner is up to 2 MM Btu/hr
  • We have to select the best suitable burner configuration based on CFD results

CFD Modelings of Premix Venturi Burner

Computational Domain

  • The computational domain is created in ANSYS space claim
  • Hight of the furnace is sufficiently taken high

Geometry of Burner

  • The computational domain for the Venturi- type burner is shown below
  • The opening of the air inlet is fixed for the present simulation
  • The 3D model was created in ANSYS space claim
  • The details of combustion modeling is discussed in the previous post

  • Details of the Burner are shown below
  • To retain the stability of the flame, a large number of mixture holes are created at the outlet of the mixing tube. The size of the hole is 0.2 inches. These holes plays the role of  flame arrester.
  • The mass flux across each hole should not exceed 6 lb/ft2-s for stable flame

Boundary Conditions for Premix Burner

  • Fuel Firing Rate: 0.25 MM Btu/hr
  • Type of Fuel : Natural Gas
  • Burner Air Inlet
    • The mass flow rate of air: 230 lbm/hr
    • Inlet temperature: 90 °F
  • Burner Fuel Air inlet
    • A mass flow rate of air: 11.7 lbm/hr
    • Inlet temperature: 80 °F
  • Ambient Condition
  • Air inlet temperature: 80­­­° F

CFD Results

Velocity Contours

  • High-velocity fuel induct the surrounding air via the venturi effect. It does need external means to supply air.
  • Inducted air and fuel are mixed in the mixing chamber. After that its velocity decreases.

















Temperature contours






CFD Modelings of Coal-Fired Burners in Boiler

Computational Domain 



CFD Results for Coal-Fired Boiler


CFD Modeling of Cement kiln with Burner



Computational Domain

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