Development of quantitative methods for sustainability assessment in process industry
Sviluppo di metodi quantitativi per l'analisi della sostenibilità di processo
Creators: name: Tugnoli, Alessandro <1981>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2008
Subjects: ING-IND/25 Impianti chimici

description: The increasing aversion to technological risks of the society requires the development of inherently
safer and environmentally friendlier processes, besides assuring the economic competitiveness of
the industrial activities. The different forms of impact (e.g. environmental, economic and societal)
are frequently characterized by conflicting reduction strategies and must be holistically taken into
account in order to identify the optimal solutions in process design. Though the literature reports an
extensive discussion of strategies and specific principles, quantitative assessment tools are required
to identify the marginal improvements in alternative design options, to allow the trade-off among
contradictory aspects and to prevent the “risk shift”.
In the present work a set of integrated quantitative tools for design assessment (i.e. design support
system) was developed. The tools were specifically dedicated to the implementation of
sustainability and inherent safety in process and plant design activities, with respect to chemical and
industrial processes in which substances dangerous for humans and environment are used or stored.
The tools were mainly devoted to the application in the stages of “conceptual” and “basic design”,
when the project is still open to changes (due to the large number of degrees of freedom) which may
comprise of strategies to improve sustainability and inherent safety. The set of developed tools
includes different phases of the design activities, all through the lifecycle of a project (inventories,
process flow diagrams, preliminary plant lay-out plans). The development of such tools gives a
substantial contribution to fill the present gap in the availability of sound supports for implementing
safety and sustainability in early phases of process design.
The proposed decision support system was based on the development of a set of leading key
performance indicators (KPIs), which ensure the assessment of economic, societal and
environmental impacts of a process (i.e. sustainability profile). The KPIs were based on impact
models (also complex), but are easy and swift in the practical application. Their full evaluation is
possible also starting from the limited data available during early process design. Innovative
reference criteria were developed to compare and aggregate the KPIs on the basis of the actual sitespecific
impact burden and the sustainability policy.
Particular attention was devoted to the development of reliable criteria and tools for the assessment
of inherent safety in different stages of the project lifecycle. The assessment follows an innovative
approach in the analysis of inherent safety, based on both the calculation of the expected
consequences of potential accidents and the evaluation of the hazards related to equipment. The
methodology overrides several problems present in the previous methods proposed for quantitative
inherent safety assessment (use of arbitrary indexes, subjective judgement, build-in assumptions,
etc.). A specific procedure was defined for the assessment of the hazards related to the formations
of undesired substances in chemical systems undergoing “out of control” conditions. In the
assessment of layout plans, “ad hoc” tools were developed to account for the hazard of domino
escalations and the safety economics.
The effectiveness and value of the tools were demonstrated by the application to a large number of
case studies concerning different kinds of design activities (choice of materials, design of the
process, of the plant, of the layout) and different types of processes/plants (chemical industry,
storage facilities, waste disposal). An experimental survey (analysis of the thermal stability of
isomers of nitrobenzaldehyde) provided the input data necessary to demonstrate the method for
inherent safety assessment of materials.