Optimum Reliability and Maintainability Allocations for Load-Sharing Continuous Flow System with Buffers

Reliability and availability of systems are traditionally provided by using different forms of redundancies such as multiple units in parallel or standby units. However, in oil and gas plants and other continuous flow large scale industrial systems, applications of redundancies are neither structurally nor economically feasible. On the other hand, multi-units sharing the load with buffers are commonly used. In these plants, buffers are essential to guarantee the steady output flow in the cases of having failed units, or having units under maintenance and repair. In these loadsharing multi-unit systems, the total capacity of the units forming the system should be greater than the design capacity of the plant by a specified margin, aiming at maximizing the system availability within constraints of allocated budgets. In the proposed work, the problem of optimal allocations of reliability and maintainability to such load-sharing continuous flow multi-units systems is considered. Optimum number of units, capacity distribution among them, and capacity of buffers will be considered as decisions variables in addition to other variables describing the performance of the system.