This study deals with the high-risk shell-and-tube heat exchangers in the effluent system of hydrogenation reaction of the petrochemical industry. The process of hydroprocessing reactor effluent system is simulated in Aspen Plus to study the distribution of corrosive medium in the three phases of oil, gas and water. The least-squares method is utilized to calculate the ammonium salt crystallization temperature. Then, the heat exchanger with risk of ammonium salt crystal corrosion is identified. Dynamic mathematical modeling of the heat exchanger is established to determine the transfer function. A temperature control system with proportional integral derivative (PID) control of the heat exchanger outlet is designed, and fuzzy logic is used to implement self-tuning of PID parameters. After MATLAB simulation, the results show the control system can achieve rapid control of the heat exchanger outlet temperature.