Evaluation of Fouling Precursors Residence Time in Distillation Tower

Fouling mechanisms in distillation towers are often evaluated by conducting batch experiments or running hot liquid process simulation (HLPS) in laboratories. In most cases however, it is difficult to relate the laboratory results to actual operation as the residence time of fouling precursors is often unknown in a distillation tower. Evaluating the residence time of fouling precursors in distillation towers is a difficult task as it involves vapor/liquid equilibriums (VLE) and internal recycles, which may differ from one component to another. Tracer test on towers are known methods that are effective for evaluating hydraulic distributions. However, they provide little insights with regards to specific components distribution. This paper discusses a method for estimating the residence time distribution (RTD) of fouling precursors in distillation towers. The method is based on simulating a tracer test experiment using a dynamic model of the system. The tracer is configured as a pseudo-component that has a boiling point, specific gravity and molecular weight identical to a specific fouling precursor. By doing so, the tracer follow similar VLE and internal recycle rates as its assigned fouling precursor and can then be used for estimating the residence time of such component.