Chemical Engineering August 2013 - 45

Outsourced : 15 containers
Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
10
20 30
40
New pinch
(July)
Opportunities for
operational changes
50 60 70 80 90 100 110 120
Number of containers
FIGURE 6. The PPPD for the second scenario of Case Study 1 shows rescheduling
of the noni factories
Outsourced : 15 containers
Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
10 20 30
40
New pinch
(July)
Rent /acquire 2
additional factories
to meet production
50 60 70 80 90 100 110 120
Number of containers
FIGURE 7. Here, the PPPD for the second scenario of Case Study 1 shows rescheduling
of the noni factories with renting additional production capacity
J
F
M
A
M
J
J
A
S
O
N
D
15 containers
5
10 15 20 25 30
Number of containers
35 40
FIGURE 8. The new PPGCC for the rescheduled scenario
of Case Study 1 is depicted here
the factory is under-utilized after the
time pinch has passed. In other words,
the company may be able to make use
of this excess capacity for producing
other products or provide the storage
service to other manufacturers.
From Figure 3, it is noted that 60
sis, Trans. of the IChemE, Part A, 80. pp.
597-605, 2002.
12. Foo, D. C. Y., others, A Heuristic-based Algebraic
Targeting technique for aggregate
planning in supply chains. Computer and
Chem. Eng., 32(10), pp. 2,217-2,232, 2008.
13. Zhelev, T. K. and Ridolfi, R. (2006). Energy
Recovery and Environmental Concerns Addressed
through Emergy-pinch Analysis, Energy,
31 (13), pp. 2,150-2,162, 2006.
14. Tan, R. R. and Foo, D. C. Y., Pinch Analysis Approach
to Carbon-constrained Energy Sector
Planning. Energy, 32(8), pp. 142-149, 2007.
15. Foo, D. C. Y., Hallale, N. and Tan, R.R., Pinch
containers are needed
to fulfill the given planning
horizon. However,
the outsourced containers
are not needed at the
beginning of the project.
In other words, the outsourced
containers may
be delayed until it is indeed
necessary. However,
the exact day when the
outsourced container is
needed cannot be seen directly
in the PPPD. This
calls for the use of the
PPGCC, which has been used extensively
for appropriate utility selection
in heat integration [1].
The construction of the PPGCC for
Case Study 1 is shown in Figure 4,
where the horizontal distance between
the source and sink composite curves
Analysis Approach to Short-term Scheduling
of Batch Reactors in Multi-purpose
Plants, Int. J. of Chem. Reactor Eng., 5, A94,
2007.
16. Tan, R. R., Ng, D. K. S. and Foo, D. C. Y., Pinch
Analysis Approach to Carbon-Constrained
Planning for Sustainable Power Generation.
J. of Cleaner Production, 17, pp. 940-944,
2009.
17. Ooi, R. E. H., and others, Planning of
Carbon Capture and Storagewith Pinch
Analysis Techniques, Chem. Eng. Res. &
Des., (in press); http://dx.doi.org/10.1016/j.
cherd.2013.04.007.
18. Foo, D. C. Y., Hallale, N. and Tan R. R., Optiof
the PPPD are plotted against time
throughout the entire planning horizon.
Once the PPGCC is constructed,
time pockets - the shaded areas in
Figure 5 - can be determined. The
time pocket is analogous to the heat
pocket for heat recovery [1], where
the required production requirement
(sink) may be supplied by internal capacity.
The opening at the top of the
PPGCC indicates when the outsourcing
(60 containers of product) are
needed. As shown, storage outsourcing
is needed between March and May
(25 containers of products), as well as
for August to September (35 containers
of products).
Scenario 2. The opportunities of
rescheduling can also be considered
with the aid of the PPPD. In a different
scenario, we shall reschedule the
noni factories in order to make use of
its excess capacity identified earlier.
In this case, it is assumed that the
factory can be rescheduled by producing
some goods earlier than originally
planned. Assuming that Factories 2
and 3 can now be rescheduled three
months ahead of the original schedule,
the pinch point moves forward to
the month of July instead of October
(see Figure 6). Note that any factory
rescheduling or operational adjustment
can only be made after the
pinch, where there is excess resource
availability. On the other hand, adjustments
before the time pinch do
not bring any benefit. Shifting the
pinch point earlier, thus gives the
company room for operational adjustment.
In this particular case, the outsourced
requirement is reduced from
60 to 15 containers. Apart from outsourcing,
the company may decide to
rent another two production facilities
each with capacities of 20 containers
during the months of August and Sepmize
Shift Scheduling Using Pinch Analysis.
Chem. Eng., July, pp. 48-52, 2010.
19. Singhvi, A., Madhavan, K. P. and Shenoy, U.
V., Pinch Analysis for Aggregated Production
Planning in Supply Chains, Comp. and
Chem. Eng., 28, pp. 993-999, 2004.
20. Ludwig, J., and others, Production Planning
by Pinch Analysis for Biomass Use in
Dynamic and Seasonal Markets, Int. J. of
Operational Res., Vol. 47, No. 8, January, pp.
2,079-2,090, 2009.
21. Foo, D. C. Y., Process Integration for Resource
Conservation, " Green Chemistry and Chemical
Engineering, " ISBN: 978-1-4398-6048-9,
CRC Press, 2012.
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