Experimental investigation of explosion mitigating properties of aqueous potassium carbonate solutions

Abstract

The oil industry operates installations and processes with important quantities of flammable substances within a wide range of pressures and temperatures. A particular hazard for this type of installations is an accidental release of a large quantity of flammable material resulting in the formation of a flammable cloud within the installation. Upon ignition, such a cloud can lead to a devastating explosion. Such accidents are commonly named “Vapor Cloud Explosions” (VCE).Water mist systems are known to be effective for inhibition and suppression of fires. Other systems for inhibition and suppression of fires are based on the action of dry powders as inhibitors. Alkali compounds, applied as powders, have proven to be effective not only for mitigation of fires but also for inhibition of vapor cloud explosions. The combination of the physical effects of water mist on flames combined with the inhibiting effects of alkali compounds on combustion chemistry might result in a superior Vapor Cloud Explosion mitigating agent.In this article, the results are given and discussed of an experimental study of explosion mitigation by using various concentrations of aqueous K2CO3 concentrations (varying from 10 to 70 g/l K2CO3) in lean, stoichiometric and rich propane/air mixtures in a 135 L channel. The tests with inhibitor-solutions were compared to that of pure water and dry tests (only propane/air). Four different congested configurations were applied, creating different degrees of turbulence and explosion violence.The experimental results show that by increasing the amount of potassium carbonate in water, an increase of the degree of mitigation (reduction of flame velocity and explosion overpressure) is observed up to possible full quenching. For the same mass loading density, aqueous solutions of K2CO3 in concentrations above 50–60 g/l have superior inhibition properties compared to dry K2CO3 powders with a particle distribution in the range of 20–100 μm.