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Aspen Plus warning "not mass balance" in a simulation including recycle streams

  • 1.  Aspen Plus warning "not mass balance" in a simulation including recycle streams

    Posted 01-11-2020 10:55
    Hi,
    I am simulating a process unit that is related to producing lignin nano particles, I have four recycle streams. When I run the program the results show a warning which says
    "STREAMS CROSSING THE LOOP CONVERGED BY $OLVER01 ARE NOT IN MASS BALANCE:
    MASS INLET FLOW = 0.33916774E+02, MASS OUTLET FLOW = 0.15844044E+01
    RELATIVE DIFFERENCE = 0.20406640E+02
    IMBALANCE MAY BE DUE TO A LARGE RECYCLE FLOW, AND A
    RELATIVELY LOOSE TEAR STREAM TOLERANCE."
    I tried different tear converging methods such as Broyden, Wegstein and etc. I also changed the tolerance, maximum iteration. However, the warning did get solved. When I do not connect the recycled streams directly to the destinations and copy the properties of the recycle streams to new ones and connect them to the destinations, the answer converges. However, if I connect the recycle streams directly to the destinations the mass balance warning appears. Please Kindly guide me what I should do to solve this issue.
    Thanks.


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    Susan J IENG
    student
    asan
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