Different Methods Obtained by PHOENICS Simulation to Improve the Performance of Pusher- Type Steel Slab Reheating Furnace

1
Different Methods Obtained by PHOENICS Simulation
to Improve the Performance of Pusher- Type Steel
Slab Reheating Furnace

• Yong Tang Jarmo Laine Timo Fabritus
  Jouko Härkki
• Oulu University
• Tel[phone] Fax[phone]
• http// www.Oulu.fi

2
1. Objective

• Study the gas flow and temperature distribution
  in the furnace
• Investigate the gas flow modification while a
  block wall is built in front of the lower burners
  in the heating zone

3
2.The Outline of the Furnace and Grids Used In
the Calculation
4
3. Model Discription

• K-? equation for turbulent flow model.
  Non-equilibrium wall function was applied
• Extended Simple Chemically-Reacting System
  (ESCRS) was selected to simulate the combustion
  and EBU model was used
• The reaction assumed
• 2CH4O2-gtCO 2COO2-gt2CO2 2H2O2-gt2H2O
• Composite flux model for radiation simulation
• Boundary conditions
• 1)The circle inlet is assumed as square
• 2) Slab surface temperatures were measured
• 3) Temperatures of inside wall ,roof and
  floor were determined from the monitor system
• 4) gas thermal property and enthalpy near the
  boundary wall was derived from the ground file,
  according to the temperature and fraction

5
4. PHOENICS Settings and Iteration Process

• Phoenics Version 3.1 of MS-DOS was used in this
  simulation.
• SATELLITE The satellite module operates in the
  batch model and stop at the first STOP line.
  There are no other special requirements for
  SATELLITE.
• GROUND The thermal boundary conditions are
  determined in the calculation and coded in the
  GROUND file. After the GROUND file is compiled
  and re-link, private executables (earexe.exe) is
  created. Type run77 earexe to start private
  EARTH.
• Iteration More than 2000 sweeps was iterated for
  coarse ,firs order scheme. About 4000sweeps was
  used for fine or higher order scheme (HQUICK). No
  significant difference was found between coarse
  mesh and fine mesh.
• Convergence was thought achieved when the values
  at the monitor point stopped changing, the sum
  residuals were reduced by several orders of
  magnitude ( from 104-6 to 101-3) and the sums of
  sources balance.

6
Monitor screen of the error residence
7
5. Results

• Flow Pattern and Gas Temperature Distribution

Gas temperature distribution
Gas flow pattern in the furnace
along longitudinal furnace, cross burners in the
heating zone
8

• The flow modification when a block wall is
  installed in the heating zone

The illustration of block wall added in front of
the lower burners in the heating zone
9
Without block wall
With a block wall
Gas velocity distribution near the burners in the
heating zone
10
6.Verification
Comparison of calculated gas temperature with
measured results at different positions in the
furnace
11
Comparison of modeled O2 distribution with
measured values in the furnace
12
7. Conclusions

• Momentum, combustion and radiation models are
  combined together to predict gas flow pattern and
  temperature distribution in the pusher-type
  reheating furnace.
• A block wall installed in front of the lower
  burners can reduce the reverse flow under the
  slab in the heating zone.
• Industry measurements indicate that the predict
  values were reasonable.