Sharif University of technology Department of chemical engineering

Master of Science

Subject

Integrated safe design of industrial processes under uncertainty

Dissertation by Mojtaba Meghdari

Supervisors Dr. Rashtchian Dr. Sharifzadeh

September 2015

Abstract

Chemical industries are associated with hazardous chemicals and extreme operating conditions.

Unsafe events can incur dramatic costs in terms of the loss of life, financial penalties and

damages to the environment. Therefore, design of industrial processes which can be operated

safely over a wide range of operating conditions is vital. Nevertheless, operation of industrial

processes is a strong function of their design. If the process is initially poorly designed,

ensuring its safe operation, if not impossible, would require costly modifications at the

operational phases. This observation is due to the fact that process design decisions (e.g. design

of process equipment) often have a physical realization and later on they are fixed throughout

the process life. Therefore, many commentators recommended that the design and the safe

operation of chemical processes should be considered simultaneously. The challenge is that

during the process design phase, there are large uncertainties in the operational conditions and

parametric values of the process models. The present research aims at developing an

optimization framework which ensures the process safe operation and simultaneously

optimizes other design objectives such as process profitability considering the associated

uncertainties. The developed optimization framework is demonstrated on the case of a hybrid

power plant including solid oxide fuel cells (SOFC) and steam/gas turbines. The significance

of this industrial application is due to the fact that power plants experience a wide range of

electricity power load. Furthermore, their behavior changes over the time. For instance, coking

of the fuel cells can change their heat transfer coefficient and affect their performance. The

results of the case study demonstrated a strong trade-off between the range of safe process

operation and the process economy in terms of the required capital investment and operating

costs. Furthermore, it was shown that it is possible to maximize the process profitability and at

the same time ensure its safe operation over a high degree of uncertainties in the operating

conditions and design parameters. While these results provide the proof of concept, they are

to large extent general and it is expect to be transferable to other industrial processes.