A systematic procedure to integrate the heat exchanger network considering pressure drops and multiple shells is described.The shell-side pressure drop correlation without resorting to correction factors is developed from the Esso method.The number of shells is calculated by considering the temperature cross in a heat exchanger instead of the designer's choice for the ratio.The network spaghetti design is solved by the optimization of total annual cost with the genetic algorithm.The case study shows that the proposed method can handle more constraints and make the computation more reliable and optimized.