Page 202 - Design of Simple and Robust Process Plants

5.6 Overall Process Simplification 187
such as cooling water, the addition of chemicals is placed in the hands of specialized
companies who supply, operate, and service these systems. This keeps the operators'
hands free to carry out more direct, process-related activities.
Utility supplies represent another area where outside companies have taken over
the ownership, operation and service. Supplies such as cooling water, steam, air,
nitrogen, and refrigeration are added to the historical supply of electricity, gas, and
water. These activities will also unload process operation from their primary task.
Such supplies can be cheaper and more reliable than on-site generation, because the
suppliers of the utilities are experienced in this field, and often operate standardized
units remotely. It is in their benefit to keep their prices competitive, and to maintain
availability and reliability. In particular, it is the standardization and robustness of
these designs, next to the capability of monitoring and operating them remotely,
that makes this approach a realistic option.
Care should be taken that contracts cover not only capital, operational costs and
service costs, but also guarantee availability and reliability. These guarantees should
include the total planned and unplanned outages in time, and also include penalties
for contract violations.
Optimization of storage areas is a very important point due to the high fixed and
operational capital involved. Storage optimization must be done in concert with the
whole supply chain. In these studies, the option for zero storage by using pipeline
and/or transport containers needs to be part of the study, and the batch process
shown in Figure 1.4 of Chapter 1 is an example of this. The optimization techniques
for sizing the storage are discussed in Chapter 9, and are based on probability anal-
ysis of supply, demand, and operation performance.

5.6.4
Strategy Around Single Component Design

This point was referred to during the description of the design philosophies. It is,
however, a general point for the process designer to consider, and will be discussed
in greater detail in Chapter 6.

Summary
Process simplification is explained with reference to different categories, all of
which should focus on the objective of more economic designs.
. The avoidance of equipment plays a dominant role, and in this respect one
might consider in line with Trevor. Kletz's statement: ªwhat does not exist
can't leak and does not cost anythingº.
± Avoiding equipment can be realized by critically reviewing the functional
need and added value of that equipment.
± Tanks and vessels are a primary target for elimination or reduction.
± In current designs, transport of fluids only very rarely benefits from forces of
gravity or pressure.
± Recovery systems in a well-designed process should be nonexistent.