Abstract:
In this work, the development of simultaneous heat and mass exchanger networks
module for ASPEN PLUS has been introduced. The module is developed as a user
interface to retrieve supplemental data from the process simulated in ASPEN PLUS and
to communicate with the optimizer called GAMS. In the network synthesis point of
view, the stage-wise superstructure originally proposed by Yee and Grossmann (1990)
is applied to construct the network structure. With the principle that the concept of
pinch is not concerned, the model formulation of the aforementioned network thus can
be classified in the class of mixed-integer nonlinear programming (MINLP)
optimization model. Although all available constraints in the model are linear, the target
on the minimum total annual cost causes the objective function in the model become
nonlinear. Therefore, the operating cost of MSAs as well as external hot/cold utilities,
and the annualized equipment cost for heat/mass exchangers can be minimized
simultaneously. Three case studies from literature - including those with 1) heat
integration system for nine process streams, 2) a single waste component for the
sweetening of coke oven gas (COG) process which attempts to remove an undesirable
hydrogen sulfide, and 3) sweetening of COG process with simultaneous heat integration
- are examined to demonstrate the applicability of proposed superstructure approach.
From the results, the synthesis of simultaneous heat and mass exchanger networks can
satisfy heat/mass balance of the process and also obtain the lower total annual cost of
the network.