Metallurgical and Materials Transactions A

, Volume 32, Issue 6, pp 1301–1308

Heat-transfer model for the acheson process

  • G. S. Gupta
  • P. Vasanth Kumar
  • V. R. Rudolph
  • M. Gupta
Article

Abstract

The Acheson process is used to manufacture silicon carbide (SiC) in a resistor furnace using petroleum coke and silica as raw materials. The process is highly inefficient, as only 10 to 15 pct of the charge gets converted into silicon carbide. No published attempt has been made to optimize this century-old process by applying mathematical modeling. Therefore, a simultaneous heat- and mass-transfer model has been developed for the resistance-heating furnace, considering silicon carbide formation as a typical carbothermal reaction. Coupled transient partial differential equations have been worked out. These equations have been solved numerically, using the implicit finite-difference method in their nondimensional form, to obtain the profiles of solid temperature and volume fraction reacted in the furnace. The trend of the computed results appears to be realistic; comparison of the results with published experimental work validates the applicability of the model’s predictions. The effects of various parameters on the process have been studied. These include void fraction, power inputs, initial concentration of silicon carbide present in the charge, etc.

Nomenclature

QR

heat generation term

r

coordinate in the radial direction

t

time

Cp

specific heat

x

fraction of silica reacted

\(\dot R\)

the rate of reaction for SiC formation

K

a constant

M

molecular weight

R

universal gas constant

T

absolute temperature

ΔS

diffusion distance

A

area of diffusion

L

length of the furnace

p

partial pressure

D

diffusion coefficient

Q

heat loss at the furnace wall

h

convective heat-transfer coefficient between air and the steel shell

r1 and r2

radius of the graphite core and furnace inwall, respectively

r3

furnace radius, including refractories

r4

furnace radius, including steel shell

ΔHR

heat of reaction for Reaction [1]

Re

resistance

I

current

Subscripts

e

effective

s

solid

0 and i

initial

SiC

silicon carbide

ss

steel shell

ref

refractory

CO

carbon monoxide

tT*

nondimensional time for the heat-balance equation

tC*

nondimensional time for the mass-balance equation

Superscript

*

nondimensional quantities

Greek Symbols

κ

thermal conductivity

ρ

density

ɛ

void fraction

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Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2001

Authors and Affiliations

  • G. S. Gupta
    • 1
  • P. Vasanth Kumar
    • 1
  • V. R. Rudolph
    • 2
  • M. Gupta
    • 3
  1. 1.the Department of MetallurgyIndian Institute of ScienceBangaloreIndia
  2. 2.the Department of Chemical EngineeringUniversity of QueenslandSt. LuciaAustralia
  3. 3.the Department of Mechanical EngineeringNational University of SingaporeSingapore

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