Information Technology Reference
In-Depth Information
CHAPTER THREE
THE SIMPLE BLOCKS
Aspen Plus provides several blocks that are suitable for, but not limited to, material-
balance-only calculations: the stream splitter, the mixer, and the simple separator
blocks. Additionally, the stoichiometric reactor, covered in Chapter Ten, is also very
useful for material-balance-only calculations. These blocks are especially important
since when they are combined to form a simple process model, the results are useful
as an initial estimate for a rigorous model of a process. In some cases, such calculations
are used as the basis for design.
Aspen Plus also provides two blocks with general utility in various aspects of
simulation. The stream duplicator block enables, for example, the execution of duplicate
processes with different thermodynamics and parameters but the same feeds. The stream
multiplier enables all elements of an input stream to be modified by a calculated
multiplier subject to the specification of a block output, such as the composition of a
component in an output stream.
3.1 MIXER/SPLITTER BLOCKS
The blocks Mixer, Fsplit, and Ssplit are available from the Aspen Plus model library
shown on the bottom of the Aspen Plus displays under the Mixers/Splitters tab, as
shown in Figure 3.1.
3.1.1 Mixer Block
The Mixer block combines an arbitrary number of input streams and produces a single
stream by a simple material balance. If the “no heat balance” option is chosen, no
other input is required. An example is shown in Figure 3.2. If
F
i
and
h
i
represent the
