# this model works fine. see comments in r1.values and the reactor model
# In the original model the reactor model was not well scaled. 
# Extensive flow balances
# generally need to be divided by a characteristic scaling value
# set based on problem input.
# many of these comments, and changes made by Ben Allan at Carnegie Mellon 
# University - thanks  
# 
DELETE TYPES;
READ FILE frpg508.a4c;
COMPILE tc of flowsheet;
BROWSE tc;
RUN tc.clear;
RUN tc.specify;
RUN tc.values;
RUN tc.seqmod;
ASSIGN tc.r1.in_ethane 100 {mole};
RUN tc.r1.values;
SOLVE tc;
BROWSE tc;

# The base case (100lb_mole) now claims
# 'diverged' but you must look at the
# residual reported to really believe it.
# For large flowrates (~10^5 mole/s},  a residual of 1e-1
# is about 1 part in 10^15 error for eq8. Scale the
# reactor flow equation 8 by  flowscale := input_ethane^3;
# or rewrite 7 and 8 in unsubstituted form. Alternatively,
# set the QRSlv option max residual(absolute) to 1e-1.

DELETE TYPES;
READ FILE frpg508.a4c;
COMPILE tc of flowsheet;
BROWSE tc;
RUN tc.clear;
RUN tc.specify;
RUN tc.values;
RUN tc.seqmod;
set ascSolvQRSlvVect(feastol) 1e-1
SOLVE tc;
BROWSE tc;