Numerical Calculation Of Vent Area Of Gaseous Vented Deflagrations

Deflagration of flammable gases in closed vessels can cause great economic loss and casualty. At present, installing rupture disks on vessels is a useful method for protecting. The investigation into venting process of deflagration is of great importance for further study of design methods of safety venting.Venting is a widely applied method to protect equipment from being destroyed by internal explosions. The key problem on vent design is the appropriate design for the vent area. With the development of computer, numerical calculation about vent design can provide reference for practical engineering application.1. Based on hydrodynamics and thermodynamics, governing equations of describing the gaseous vented deflagrations are deduced. Runge-Kutta algorithm is adopted in program to calculate the vent area of gaseous vented deflagrations in spherical vessels.2. Based on the investigation into gaseous vented deflagrations in spherical vessels, vent area of vented gaseous deflagrations in cylindrical vessels is calculated by modifying the corresponding governing equations. The difference of vented deflagrations between spherical vessel and cylindrical vessel is the geometrical sizing, so development of flame figure in vessel is different.3. Visual Basic language is used to design GUI (graphical user interface) of numerical calculation system, which providing a database of gaseous physical property parameters. The record of database can be compiled, such as accession, modification, deletion etc. The vent area of different kinds of flammable gases at different initial conditions (such as temperature and pressure) can be calculated by inputting design parameters and physical property parameters according to interface presentation.4. Several conclusions have been drawn by computed results as follows: (1) As initial pressure and vent pressure are constant the vent area increases with decreasing reduced pressure;(2) The higher the vessel dimension is, the greater the vent area is, with given design parameters;(3) If reduced pressure and vent pressure are pacified, vent area increases by enhancing initial pressure.By comparing numerical results with experimental data, the error for spherical vessels and cylindrical vessels is within 10% and 20% respectively. Therefore the numerical calculationprogram can be applied to calculate the vent area of gaseous vented deflagrations, and provide an effective safety vent design for project planners.