Page 266 - Sustainability in the Process Industry Integration and Optimization

E x a m p l e s a n d Ca s e S t u d i e s 243

10.4.2 Utility Placement: Second Problem

Problem 7: Task Assignment
A process involves the set of process streams described in Table 10.18.
The utilities available to satisfy its heating and cooling requirements
are given in Table 10.19.
For the HEN to be designed, assume ΔT = 30°C.
min
(a) Identify the minimum heating duty, the minimum cooling
duty, and the Process Pinch location.
(b) Plot the GCC.
(c) Perform an appropriate placement of the utilities against the
GCC so as to achieve minimum total cost of the utilities.
(1) Draft the placement on the GCC.
(2) Calculate the total duty for each of the utilities.
(3) Calculate the total utility cost for the problem.
(d) Consider the following ways to reduce the utility costs
further, and comment on their suitability for application to

Stream T [°C] T [°C] CP [MW/°C] ΔH [MW]
s t
H1 175 75 3.5
H2 100 40 2.4
H3 180 130 1.5
H4 195.1 195 100
C1 50 150 2.0
C2 140 140.1 150
C3 80 140 1.5
C4 20 80 3.0

TABLE 10.18 Process Streams Data for Problem 7

Name T [°C] T [°C] Cost [$/MWy]
s t
HP steam 300.1 300 65000
MP steam 200.1 200 50000
Cooling water 15.0 20.0 7000
Chilled water 5.0 10.0 30000

TABLE 10.19 Utilities Available for Problem 7