CFD model of fluid flow and particle deposition during cryogenic condensation

Abstract

Cryogenic condensation is an attractive option for controlling VOC emissions. Cryogenic condensation can offer lower operational costs than conventional abatement technologies like thermal oxidation and adsorption. At the low temperatures (ca. −100 °C) used in cryogenic condensation, many high melting point VOCs will freeze or desublimate. A fine particulate solid could form under the temperature gradients inside the condenser, becoming entrained in the gas phase on exit. This paper reports results in modelling the process using CFD. In this paper we present an inert DPM model in 3D and a dynamic DPM model in 2D to investigate this problem through CFD.The 3D results demonstrate particles must grow beyond a certain size to prevent entrainment in the outlet gas flow. These sizes are: 12 μm at 150 Nm³/h (Stk99% = 0.18 at Redh = 4600); 16 μm at 100 Nm³/h (Stk99% = 0.22 at Redh = 3000); 23 μm at 50 Nm³/h (Stk99% = 0.23 at Redh = 1500). The 2D results demonstrate a DPM model (Eulerian–Lagrangian model) of nucleation and growth of particles during cryogenic condensation.