Numerical modelling of the discharge behaviour of particles from a gas vessel

Abstract

Particle-laden gas flows occur in a wide variety of process technologies. It is therefore a common safety scenario to understand how many particles will escape in the event of a leak or emergency pressure relief. Therefore, a vessel filled with gas and homogeneously dispersed solid particles was considered. The aim was to derive a model to describe the discharge of arbitrary spherical particles. For this purpose, multiple numerical simulations were performed with ANSYS CFX©. A cylindrical vessel with a volume of 2 m³, a 25 mm opening and a length to diameter ratio of 2 was considered. The system was considered adiabatic, isentropic, compressible, and subcritical with an ideal gas. The velocity field was described with a one-way Euler-Lagrange method. The particle density, particle size, the gas in the vessel, as well as the initial temperature and pressure in the vessel were varied. Based on a dimensional analysis a model was developed to estimate the discharged mass of particles. This model achieves a small mean absolute deviation from the simulation data of −0.03%. The prediction model is thus able to correctly represent all variables varied without having to carry out single complex numerical simulations. The model is the first model to derive the discharge behaviour of particles from pressure vessels.

Keywords

• Gas dynamics
• Multi-phase flow
• Particle flow
• Compressible flows
• Transient