Page 77 - Design of Simple and Robust Process Plants

3.3 Design Philosophies 61
The above illustration emphasizes the benefit of evaluating inherently safer design
philosophies during the design. As a standard, safety reviews are performed during
different stages of the design of a process, and often result in add-ons. The evalua-
tion of the inherently safer set-up during the conceptual design forms the largest
contribution to simple robust and safer design. (For a reference to this, see the excel-
lent training package of the IChemE on Inherently Safer Process Design.)

Summary
The application of inherently safer design philosophies based on the guiding words:
ªminimizeº; ªsubstituteº; ªmoderateº; and ªsimplifyº result in a safer design and in
a more simple and robust plant design.

3.3.12
Environmentally Sound Design

While environmentally sound designs might be seen as a local problem, it is the
author's opinion that such an approach may lead to designs with high cost over the
lifetime of a process. Environmental requirements are subject to rapid changes;
initially, these were driven by the western world but are becoming increasingly glo-
bal as they are also adopted by developing countries.
Both the designs and the products must comply with a minimal environmental
load. During the last decades of the 20th century all types of technical solutions
were developed in order to minimize the environmental load. Inevitably, such devel-
opments will keep pace with the environmental requirements.
The concept of sustainability is introduced at global scale, driven mainly by the
United Nations (see ISO 14040/41/42/43). This is defined as: ªsustainable develop-
ment meets needs of the present, without compromising the ability of the future generations
to meet their own needsº (Brundtland, 1987).
The development in sustainability is one which is also strongly influenced by con-
sumer markets. An example is the car industry, which analyzes the environmental
contribution of individual components selected for the production of cars that are
more environmentally friendly. Similar results have been published in Eco-profiles
of the European plastic industry (APME, 1997).
Next to the pollution of air, water, and soil, the main environmental factors of
concern are those of nuisance and risk. Nuisances,- such as noise and skyline pollu-
tion-, driven by local situations, will in time, evolve to generate more stringent local
requirements. Risk of processing facilities and transportation of hazardous materi-
als will have to comply with more stringent governmental regulations.
Consequently, processes designs will need to attack environmental problems by
using a sequential approach (Figure 3.8):

. Prevent/minimize
. Recycle in process/reuse in process
. Recycle between processes
. Destroy with recovery