Cost-Effective Reconstruction of Existing Two-Stream Heat Exchanger Systems
摘要
The paper proposes a method for optimizing a two-stream heat exchanger system, taking into account technical constraints imposed by heat exchange equipment, and the economic efficiency of the retrofit project. The optimization of the heat exchanger network is carried out considering the necessity of conducting an safety expert review in cases where process flow temperatures exceed the design temperatures of heat exchange equipment. This method was applied to optimize energy consumption at a real hydrocracking unit. Two types of heat exchange equipment are considered, specifically, shell-and-tube and plate type heat exchangers, for a possible increase in the heat transfer area within the existing heat recovery system. For shell-and-tube heat exchangers, the minimum annual cost of the retrofit project is observed at a 500 m2 increase in heat transfer area, which corresponds to the installation of a two-section heat exchanger. This enables reducing specific consumption of hot utilities by 51% and cold utilities by 31%, with a payback period of ~1.5 years. At the same time, for plate heat exchangers, the minimum annual cost is achieved at a 400 m2 increase in heat transfer area. The cost of such a retrofit project is 18% lower than that for shell-and-tube exchangers, while the reduction in specific consumption of hot and cold utilities is 66 and 40%, respectively.