Page 45 - Materials Chemistry, Second Edition

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generally on Paretian’s theory of well-being, in which individuals facing external
effects judge their importance for their quality of life. Preferences may be shown in
monetary terms, just as in market choices. In this way, the final assessment of the
marginal damage balance (external costs) and marginal abatement costs (internal
costs) may be carried out in one monetary unit: currency (dollar, euro, yen), which
is a globally accepted reference in decision-making (Dasgupta and Pearce, 1972;
Nas, 1996).

1.5.4.5 Process Simulation

Process re-engineering is one of the applications within chemical engineering that
shows increases in interest year after year. The vast majority of plants have been
built and are currently operating so as to obtain the highest possible return using
available equipment and reduce investment. New process synthesis tools allow
analysis, in a relatively simple and fast way, of whether the optimum current process
setting is the best and to assess possibilities for improvement. To attain this, it is
necessary to count on models with an exact and precise representation of equipment
operation. In the first place, it is necessary to adjust these models using plant data
to ensure successful predictions. After the base case has been obtained, exploring
alternative design choices and assessing their applicability through equipment sizing
begins. At this point, it is necessary to assess in detail the possibilities for imple-
menting the proposed alternative by means of detailed research of the most promising
alternatives (detailed sizing, economic estimate, cost analysis, etc.). Apart from these
applications, process simulation has proved to be the fundamental tool for detecting
bottlenecks in processes and operation problems, and in obtaining ideal operating
conditions for the environment.

15.4.6 Accident Prevention

To prevent accidents, it is necessary to determine the environmental risk associated
with a facility or process operation resulting from undesirable events or accidents.
Undesirable events are those unforeseen events that accidentally cause the emission
of pollutants into the environment. Analysis of undesirable events (accidents) must
include the following phases:

• Analysis of facilities and information gathering
• Identification of the most representative accident scenarios
• Establishment of accident probability for these scenarios and its evolution
• Establishment of consequences associated with each accident scenario
assessed (scope of associated physical effects)
• Establishment of the impact these physical effects have on the environ-
ment

Fail trees and event trees are applied when accident prevention assessments are
undertaken (AICHE, 1985).

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