For the chemical processes, multiple fluctuations exist, and elucidating the system's dynamic changes is essential in improving its adaptability. With changes in reactor and separator operating conditions and cascading effects related to the system's topological structure considered, a comprehensive framework is established to target the disturbance propagation path and determine cost-effective debottlenecking strategies. Relations among distillation column parameters and the seasonal change in ambient temperature are deduced considering meteorological data, and the utility demand or column pressure under various conditions can be determined. All independent subsystems of the heat exchanger network and their heat surplus/deficit are identified based on the improved information flow diagram and output difference analysis, and the disturbance propagation path is determined. Correlations are deduced to clarify the heat transfer capacity requirement under fluctuating states, and the bottlenecks and cost-effective debottlenecking strategy without topology modification are identified at different stages. The proposed method is intuitive and efficient and can be applied in chemical processes' enhancement, retrofitting, and fault diagnosis. A benzene alkylation process is studied, with the total annual cost decreased by 3.4 %.