Adiabatic Converter for Sulfur Trioxide Production

mole fraction of

SO

2

0.095

A furnace is necessary for the combustion of liquid sulfur in air:

S

liq

+

O

2



SO

2

.

The sulfur dioxide then undergoes a catalytic conversion into sulfur trioxide,

SO

3

, in an adiabatic reactor:

SO

2

+

1

2

O

2

⇌

SO

3

.

Sulfur trioxide is prepared on a massive scale as a precursor to sulfuric acid.

This Demonstration computes the extent of reaction,

ξ

, the exit temperature,

T

3

, and the composition of the effluent for the adiabatic converter used for

SO

3

production. To do so, one has to write: (1) the chemical equilibrium using the equilibrium constant

K

2

(T)=exp(30.2021-0.048292T+0.0000186433

2

T

)

, obtained by fitting the free energy data versus temperature for

SO

2

and

SO

3

, and (2) the energy balance:

H

2

=

H

3

, which exploits the fact that the converter is adiabatic.

Finally, the temperature at the entrance of the converter is chosen equal to

T

2

=700 Kelvin, a value that depends on the energy produced in the furnace,

Q

, used to generate live or superheated steam.

The user-specified values of the mole fraction of

SO

2

are in the range typically used in the industry.