Information Technology Reference
In-Depth Information
Figure 9.1
Heater block primary input.
1
2
H1
5
4
3
H2
Figure 9.2
Two heaters modeling a heat exchanger.
An example of a process in which heat exchangers are replaced with heaters is shown
in Figure 9.3. The heat exchangers here are used to conserve energy by extracting heat
from the bottoms of the columns and transferring part of the available energy to the
column feeds. An important aspect of using heaters rather than heat exchangers is that
the calculations can be performed once through, and no tear streams are required. This
is illustrated by Aspen Plus's analysis of the process, given in Figure 9.4. In most
cases, whenever a heat exchanger is placed on a flowsheet, a tear stream is introduced.
This is illustrated in Figure 9.5, where the heaters from the Figure 9.3 process are
replaced by heat exchangers. Aspen Plus's analysis, in Figure 9.6, shows that one tear
stream has been generated for each heat exchanger inserted. Details of the solution to
the process with four heaters are given at Examples/fourheatersflowsheet. Similarly,
the two-heat-exchanger process is provided at Examples/twoheatxflowsheets.
