9/25/2010

Aspen Plus Hydrocracker V7.2 User's Guide

http://www.cadfamily.com/downinfo/301327.html

Changing Specifications with
Specification Options
What if the plant we are modeling has both a DP cell and an outlet pressure
gauge? We have a choice as to which to use. From a mathematical
standpoint, it is just as valid to declare PRES_OUT a MEAS and DELTAP a
CALC as the other way around. Thus we have two possible variable
specifications affecting both our simulation and parameter-fitting modes.
In Aspen Plus Hydrocracker this type of spec swap is made using the
Specification Options button on the Flow Diagram Sheet
A specification option is a pre-set set of alternate specifications that are
equally mathematically valid. The specification sets is set by the EBS script
defined on the ES Scripts worksheet. One of the sets may be more
appropriate for a given unit based on its configuration, control strategy,
instrumentation, type of lab test, mass or volume basis for flowmeters, or a
variety of other reasons.

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