Aspen-Warning in calculation by Fortran

Shell Programming and Scripting
1

Would you please tell me what I can do to solve this warning in aspen program? I want to calculate flow and mass balance for this program.

*   WARNING DURING FLOWSHEET ANALYSIS
      FORTRAN READ-VAR VOLFLOW IN FORTRAN BLOCK VALKIN2
      APPEARS ON THE LEFT-HAND SIDE OF AN ASSIGNMENT STATEMENT.
*   WARNING DURING FLOWSHEET ANALYSIS
      FORTRAN READ-VAR T IN FORTRAN BLOCK VALKIN1
      APPEARS ON THE LEFT-HAND SIDE OF AN ASSIGNMENT STATEMENT.

T is a import variable as this :Block-Var Block=REACTOR1 Variable=TEMP Sentence=PARAM Units=C

VOLFLOW is a import varaible this :Stream-Var Stream=ACIDPROD Substream=MIXED Variable=STDVOL-FLOW Units=cum/day

Fortran Calculation is:
A = 0.00000001
      AA1 = ARG + HIS + LYS + TYR + TRY + PHE + CYS + MET + THR + SER
      AA2 = LEU + ISO + VAL + GLU + ASP + GLY + ALA + PRO
      AA = AA1 + AA2
       
      IF (AA .EQ. 0.0) THEN
          AA = AA + A
      ENDIF

      IF (VOLFLOW.EQ. 0.0) THEN
          VOLFLOW = VOLFLOW + A
      ENDIF
N = 1.0 / (1.0 + 0.3 / (AA / VOLFLOW))
T = T + 273.15
      T0 = 298
      Z = 70.0 * EXP(-(-14143.72619 / 8.314) * (1.0 / T - 1.0 / T0))

Thanks for your attention
2

Your Aspen FORTRAN block assigns new values to imported read-only variables T and VOLFLOW, which causes the warnings.

Use local variables instead, for example TK = T + 273.15 and VF = VOLFLOW, then use TK and VF in the calculations.

3

in addition to @Neo 's feedback, just ensure variables are the correct type - classic fortran I->N are integers the rest are float/double .... , ie 'N = 1.0 / (1.0 + 0.3 / (AA / VOLFLOW))' where N will be an integer result not a float/double - so precision is lost

4

The implicit declaration is deprecated.
Better declare everything, and have

implicit none
5

(duck.ai): Aspen Plus is a software used for process simulation, and it can utilize Fortran for custom kinetic subroutines. To integrate Fortran code with Aspen, you typically need to write the code in Fortran 77 for compatibility, as newer versions may not support Fortran 95 directly. Fortran 77 code does not live in modules and should be written as standalone subroutines.

6

Thanks Neo,

I will do this roll, I hope I get the results.

7

Thanks mumkeHoller,

But we have alot of import variable,therefor can't control calculated N.

8

As per the Aspen help,only Fortran 77 is confirmed and approparte.

9

I did this roll,only one variable solved and removed the warrning.All variable are the similar equetions withe IF..Then ...Endif.

These are remaind:

IF (VOLFLOW.EQ. 0.0) THEN

VOLFLOW =VOLFLOW+ A

ENDIF

N = 1.0 / (1.0 + 0.3 / (AA / VOLFLOW))

WARNING DURING FLOWSHEET ANALYSIS FORTRAN READ-VAR VOLFLOW IN FORTRAN BLOCK AMIKIN2 APPEARS ON THE LEFT-HAND SIDE OF AN ASSIGNMENT STATEMENT.

10

As suggested before:
at an early point put it in a read/write variable
VF = VOLFLOW
then use VF instead of VOLFLOW

11

Thanks,Warning resolved.:+1: