Further Cooling of Furnace Gases

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Further Cooling of Furnace Gases

• P M V Subbarao
• Professor
• Mechanical Engineering Department

Change the Modes of Heat Transfer for Better use.
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Measures of Furnace Performance
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Temperature Field Coefficient

• Temperature field coefficient accounts for the
  temperature distribution in the furnace.
• It is a function of relative level of the burners
  and on the type of fuels burnt.
• The expression of M is given as

• Z r is the relative position of highest
  temperature zone wrt to furnace bottom.
• DZ is a correction factor for tilt of burners.
• C1 C2 are constants depend on fuel quality

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Distribution of Heat Flux

• Average Heat flux can be calculated using

• As the temperature and emissivity of flame is not
  uniform in the furnace volume, the local heat
  flux is not uniform.
• Actual local wall temperature depends on the
  value of local heat flux.
• Special experiments are carried out to find the
  heat flux distribution on water wall.

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Measurement of Local Heat Flux Distribution
Control System
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Distribution of Heat Flux
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Distribution of Heat Flux
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Calculation of Non-uniformity of Heat Flux

• Experimental determination of zone wise value of
  non-uniformity index, hi .
• Calculate zone wise distribution of heat load.
• Develop a local resistance network to compute
  local wall temperature.

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Elaborate Models for Better Analysis

• Self-absorbing Models
• Directional Averaging Methods
• 2-Flux, 4-Flux, Multiflux, DOM
• Differential Approximation Method
• Moment, Modified- Moment, PN Appro
• Energy Methods
• Zone, MCM, Numerical (FD, FV)
• Hybrid Methods
• DTM, Ray Tracing ,Radiation Element

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Format of Report

• At lease four references (journal/conference
  publications).
• Basic theory, Verification through standard
  problems, Special problems solved.
• Formulation of this method for Furnace cooling.
• All clues to model
• Complex flame and furnace geometry.
• Complex properties of flame and gas.
• Boundary conditions.

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Evaluation

• Submission of report 20th April 2011.
• Presentations 23rd April 2011 (Saturday 10.00
  am onwards).
• 30 to 40 weightage.

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Have we completed furnace cooling ????
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Thermal Structure of A SG
DPNL
SH
R H T R
drum
screen tubes
Platen SHTR
Furnace
Bottom ash
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Paths of Steam and Gas
Drum
Water walls
Economizer
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Furnace Energy Balance
Enthalpy to be lost by hot gases
Water walls
Economizer
Furnace
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Other Radiative Exits of A Furnace
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