Numerical investigation on prevention of fouling in the horizontal tube heat exchanger: Particle distribution and pressure drop

Abstract

To improve the performance of fouling prevention in liquid–solid fluidized bed heat exchanger with the horizontal tube bundle, parametric study of particle distribution and pressure drop in the heat exchanger was numerically conducted. Eulerian multiphase fluid model was used to calculate the flow of liquid–solid two phase in heat exchanger by means of the commercial software Fluent. In the simulation result, it was demonstrated that more particles occurred in the lower tubes of the horizontal tube bundle in low velocity due to the lack of full fluidization. Relative to that in low velocity, uniformity distribution of particle was obtained in high velocity which was accompanied with greater dynamic pressure drop. The particle with the greater density and diameter was inclined to sediment in the lower tubes due to larger sediment velocity and difficulty in the realization of full fluidization. Meanwhile an increase in size and density of particle would bring about greater pressure drop originating from more particle kinetic energy consumed. Effect of volume fraction of solid phase on particle distribution and pressure was discussed. It showed that an increase in volume fraction of solid phase led to significant rise of pressure drop. It was because consumed kinetic energy and collision energy of particles were greatly amplified with the increasing volume fraction of solid phase. Therefore greater volume fraction of solid phase, especially for the particle with the greater diameter and density, would not be recommended in the performance of fouling prevention in the horizontal tube bundle heat exchanger.