Among the separation devices used to remove minute droplets of liquid from a gas stream, wave plate mist eliminators, which separate the two phases by inertial impaction, are usually adopted in many applications. Re-entrainment limits the gas-liquid separator performance because it causes a sharp decrease in separation efficiency and therefore gas velocity cannot exceed a certain value. This work presents new experimental data for the critical gas velocity at which re-entrainment occurs in industrial wave plate mist eliminators operated at atmospheric conditions with horizontal flow. The results show how the critical gas velocity is influenced by physical properties and flow rate of the liquid and by separator geometry. This paper also presents a new model for predicting re-entrainment based on the calculation of the liquid load on each plate between two consecutive bends of the separator. To this scope, an efficiency model was used to evaluate liquid flow over each plate and a mechanistic model was developed to compute the re-entrainment from the trickles which are formed on the plates by the coalescence of liquid droplets that impinge on the blades of the wave plate mist eliminator. The model developed takes into account the parameters which influence re-entrainment according to experimental data, it could be used to predict the critical velocity for different wave plate mist eliminators and therefore it is useful to design new ones.
A mechanistic model for re-entrainment in wave plate demisters
BRUNAZZI, ELISABETTA;
2004-01-01
Abstract
Among the separation devices used to remove minute droplets of liquid from a gas stream, wave plate mist eliminators, which separate the two phases by inertial impaction, are usually adopted in many applications. Re-entrainment limits the gas-liquid separator performance because it causes a sharp decrease in separation efficiency and therefore gas velocity cannot exceed a certain value. This work presents new experimental data for the critical gas velocity at which re-entrainment occurs in industrial wave plate mist eliminators operated at atmospheric conditions with horizontal flow. The results show how the critical gas velocity is influenced by physical properties and flow rate of the liquid and by separator geometry. This paper also presents a new model for predicting re-entrainment based on the calculation of the liquid load on each plate between two consecutive bends of the separator. To this scope, an efficiency model was used to evaluate liquid flow over each plate and a mechanistic model was developed to compute the re-entrainment from the trickles which are formed on the plates by the coalescence of liquid droplets that impinge on the blades of the wave plate mist eliminator. The model developed takes into account the parameters which influence re-entrainment according to experimental data, it could be used to predict the critical velocity for different wave plate mist eliminators and therefore it is useful to design new ones.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
