Reliability issues in the design and optimization of process utility systems

The reliability of process utility systems is a prime consideration for both their design and operation. This paper combines the optimization of utility system performance with reliability theory based on Markov analysis. Operation mode is first to be considered, e.g. hot standby, cold standby, load-sharing, etc. Downtime during start up has been considered for the first time. When optimising the working load, the downstream processes are also considered, so as to minimize the total penalty cost due to shutting down of the units serviced by the utility system. The proposed methodology combines the operation and design problems and optimizes them simultaneously.