NESC0662 SOLVEX

1. NAME OR DESIGNATION OF PROGRAM:  SOLVEX

3. DESCRIPTION OF PROBLEM OR FUNCTION

SOLVEX simulates  the dynamic
and steady-state behavior of solvent  extraction banks composed of
either  mixer-settlers  or centrifugal  contactors.   Two  options
permit terminating dynamic phases by time  or by achieving steady-
state,  and  a third  option  permits  artificial rapid  close  to
steady-state.  Distribution data  may be expressed in  the form of
tables or cubic polynomial equations.

4. METHOD OF SOLUTION

SOLVEX uses  a finite-difference  solution of
the differential  equations describing the material  balance.  For
both  dynamic and  steady-state options  the calculation  proceeds
from stage  1 through  the last  stage specified  by the  user for
successive time intervals, beginning at  time zero with pure water
and  pure solvent  in the  bank.   In the  steady-state case  time
merely corresponds to number of iterations.  The rate of change in
the  inventory of  a  given component  in either  the  mixer or  a
settler zone is proportional to the flow of that component in less
the component  flow out.   Input concentrations  to the  stage are
taken as the output concentrations from adjacent stages during the
previous  time  interval and  the  equations  are solved  for  the
aqueous and  organic exit concentrations  during the  current time
interval.  Concentrations from the mixer and each settler zone are
calculated before proceeding to the next stage.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of -
   24 stages for the bank
    5 chemical components
    5 tables and 5 equations of distribution data
    2 methods of expressing distribution of each component

6. TYPICAL RUNNING TIME

Three seconds  per steady-state  problem is
typical.   One second  of  computer  time simulates  approximately
eight  minutes of  the  solvent  extraction process.   The  sample
problem took about six minutes of  CPU time to compile and execute
on Argonne's IBM370/195.

7. UNUSUAL FEATURES OF THE PROGRAM

SOLVEX  allows multiple  problem
input, as many  as 50 lumped parameter zones in  each settler, and
flexible distribution data input.

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES

W.  C.  Scotten,  SOLVEX -  A  Computer  Program  for
Simulation  of Solvent  Extraction  Processes, DP-1391,  September
1975.

11. MACHINE REQUIREMENTS

Less than  125K bytes are required  for the
load module.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   OS/360.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHOR

                 W. C. Scotten
                 Savannah River Laboratory
                 E. I. duPont de Nemours and Company, Inc.
                 Aiken, South Carolina  29801

File name	File description	Records
NESC0662_01.001	SOURCE (F4,EBCDIC)	765
NESC0662_01.002	SAMPLE INPUT DATA	31
NESC0662_01.003	SAMPLE OUTPUT	1117