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ADIABAT

Adiabatic temperature calculations for the mixing of different reaction streams

This application is used for the calculation of the temperature resulting from the chemical reaction between different reaction streams. The calculations assume that there is no loss of heat to the surroundings (ie adiabatic conditions). The reaction streams may have different initial temperatures.

The application is number 11.

set user_v(application_code) = 11 !

Before initiating the calculations it is necessary to define a datafile for the full system to be covered by the calculations and to specify the pressure. It is possible to classify any phases required to be absent or identified as giving rise to miscibility gaps for each stream separately. All this can be set up using the normal APPLICATION commands within MTDATA eg:

access define system 'Fe,S,O,N' source sub !

Initially it is necessary to provide an estimate of the final temperature eg:

set user_v(final t) = 2500 !

and the number of reaction streams that will be brought into equilibrium prior to mixing eg:

set user_v(no of streams) =3 !

For each reaction in turn it is necessary to specify the composition, the temperature and compute the equilibrium state. In this example the first reaction scheme is FeS at 298.15 K. eg:

set user_v(stream no) = 1 !
set n(1) 1 n(2) 1 !
set temp 298.15 ! compute !

MTDATA then calculated the properties of this initial state and displays the phases present in equilibrium and the calculated enthalpy.

Similarly for the other reaction streams. The second reaction stream in oxygen at 298.15 K, while the third is nitrogen at 500 K.

set user_v(stream no) = 2 !
set n(3) 2 !
set temp 298.15 ! compute !

set user_v(stream no) = 3 !
set n(4) 8 !
set temp 500 ! compute !

Finally the output stream, defined as stream number 99 needs to be specified: eg

set user_v(stream no) = 99 !

In this particular case we have decided to suppress the formation of FeO

classify absent p(FeO) !

Finally, giving the compute command initiates the calculation of the adiabatic temperature.

compute !

The results of the calculation are displayed on the screen but are also sent to the ".mpr" file.


Stream 1 Initial temperature = 298.15
Equilibrium species Moles
FeS 1.0000000
Initial Enthalpy= -101300.0

Stream 2 Initial temperature = 298.15
Equilibrium species Moles
O2 1.0000000
Initial Enthalpy= 0.0

Stream 3 Initial temperature = 500.00
Equilibrium species Moles
N2 4.0000000
Initial Enthalpy= 23632.2

Total initial enthalpy = -77667.8
Overall composition in moles:
Fe 1.00000E+00
S 1.00000E+00
O 2.00000E+00
N 8.00000E+00

Iterations to find Delta H = 0
Iteration   0 Temperature = 298.15  Enthalpy change = -458904.5
Iteration   1 Temperature = 2500.00 Enthalpy change = 313499.1
Iteration   2 Temperature = 1606.32 Enthalpy change = -53039.3
Iteration   3 Temperature = 1735.64 Enthalpy change = 36548.7
Iteration   4 Temperature = 1670.98 Enthalpy change = 17459.2
Iteration   5 Temperature = 1654.97 Enthalpy change = 12823.4
Iteration   6 Temperature = 1630.65 Enthalpy change = -47023.8
Iteration   7 Temperature = 1649.76 Enthalpy change = -36752.9
Iteration   8 Temperature = 1652.36 Enthalpy change = 12072.4
Iteration   9 Temperature = 1651.72 Enthalpy change = 10210.3
Iteration  10 Temperature = 1650.74 Enthalpy change = -12577.1
Iteration  11 Temperature = 1651.28 Enthalpy change = -130.1
Iteration  12 Temperature = 1651.29 Enthalpy change = -1.3
Iteration  13 Temperature = 1651.29 Enthalpy change = 0.0
Iteration  14 Temperature = 1651.29 Enthalpy change = 0.0
Iteration  15 Temperature = 1651.50 Enthalpy change = 5079.0
Iteration  16 Temperature = 1651.29 Enthalpy change = 0.0
Iteration  17 Temperature = 1651.29 Enthalpy change = 0.0
Successful interpolation
Enthalpy change = 0.00

Equilibrium species           Moles
FeS                    1.286283368991E-06
N2                     3.99999760632
NO                     3.772755981473E-06
NS                     1.014610241059E-06
OS                     1.254988687912E-02
OS2                    3.787216321091E-03
O2S                    0.573496865618
O3S                    1.590612351562E-06
S                      1.198879082417E-04
S2                     7.903325317726E-02
S3                     1.387798262995E-04
Fe0.947O               0.633147976860
Fe3O4                  5.087815955711E-02
FeS                    0.247772189613

Gibbs energy = -2390530.0 J

Adiabatic Temperature = 1651.29 K

 

Updated 14 April 2010