الگوريتم جديد تجزيه سازي براي اصلاح شبكه مبدل هاي حرارتي

A New Decomposition Algorithm for HENs Retrofit

In present paper a new decomposition algorithm is introduced to reduce energy consumption. In this algorithm, some rules and assumptions are considered to minimize the costs of fluid transmission such as piping costs, associated pumping costs and the plantʹs complexity. The algorithm has a good flexibility to be applied for vast majority of industrial process plants. The algorithm is consisted of two steps. At first, by using the concept of zoning in grassroots design, the existing HENs divided into two or more primary substructures (sub-networks) with considering the limitations of fluid transmission. At primary substructures, each heat exchanger could be belonged to one or more substructures. The second step is to decrease the substructure components by applying plantʹs constrains such as operability, layout of components and heat exchangerʹs materials in each substructure. Eventually, the final substructures achieved, are independent and there is no heat transfer across the different substructures due to the limitation of the fluid transmission. The existence of path in each substructure is led to opportunities for heat recovery in retrofit design. Path analysis in each substructure is a beneficial tool to identify the streams which have capability to adapt process to process heat transfer. These streams may cross different substructure simultaneously. Each substructure could be modified by retrofit methods. Also, in this a new algorithm of retrofitting HENs which is useful when there is no process to process heat exchanger is introduced. The case-study which is chosen is Acetic Acid plant of FPC (Fanavaran Petrochemical Company). The HENs of FPC has been divided into substructures and each one has been retrofitted by use of new retrofit method.