A Study on crystallization temperature and rate of ammonium salt in the high-pressure hydrogenation heat exchanger

¹ Key Laboratory of Pressure Systems and Safety, MOE, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, PR China.
² Sinopec Engineering Incorporation, Beijing 100101, PR China.
³ Tianjin Petrochemical Equipment and Instrumentation Research Institute, Tianjin 300451, PR China.

^* Corresponding author. E-mail address: zhougy@ecust.edu.cn

Abstract

Ammonium salt crystallization corrosion failure is an essential problem in the failure of high-pressure hydrogenation heat exchangers. The crystallization equilibrium curves of NH₄Cl and NH₄HS under different pressures were established according to the ammonium salt crystallization process in the high-pressure hydrogenation heat exchange unit, and the crystallization equilibrium temperatures of NH₄Cl and NH₄HS were obtained based on Aspen Plus. In addition, a prediction model for the crystallization temperature of ammonium salt was established, then the relationship between crystallization temperature and rate of ammonium salts was elaborated. The results indicate that the initial crystallization temperatures of NH₄Cl and NH₄HS are respectively 198.95°c and 134.45°c when the system pressure is 10MPa, and the temperature is 433.15K. The maximum crystallization rate of NH₄Cl and NH₄HS occur at the initial crystallization temperature, respectively 0.104kg/h and 29.23kg/h. The crystallization rate of NH₄HS is three orders of magnitude higher than that of NH₄Cl.