Interaction of Steam Curtains with High-pressure Jets

Abstract

In the industrial context, the risk of accidental release to the environment is an event which can occur in different chemical plant areas and cause serious consequences. In the presence of a hazard, risk management involves reducing the probability or the magnitude of the damage without extinguishing the hazard itself. Forms of mitigation can be primary or secondary, according to the target chosen to work on: primary refers to a reduction of the vulnerabilities of the element interested in a possible breakage (for example, hardening the coating of the device), whereas secondary mitigation refers to reduce the effects (consequences around the broken one). Considering the design of the equipment in a state-of-the-art manner, secondary mitigation methods focus on three possible strategies: procedural systems, passive-type systems, and active-type systems. Passive-type systems are devices designed to confine the leakage to a target area, defend a sensitive area using physical barriers or protect the equipment (such as fireproof coatings in the presence of fuels). Active mitigation systems, on the other hand, exploit the introduction of turbulence in the dispersing cloud, e.g., by adding a fluid to it, and could be successful with gas releases. Among the active mitigation barriers, one of the devices considered is the vapour curtain, but nowadays the understanding of the variables involved in their effectiveness, especially how to manipulate them to achieve the best result, is still not entirely clear. This work aims to show the efficiency of steam curtains in diluting a high-pressure methane jet by conducting computational fluid dynamics simulations with ANSYS 19.1® software. In doing so, several evaluations were made on the impact that certain operational parameters may have on the efficiency of the system, such as the pressure of the vapour, the position of the vapour curtain along the axis of the release and the amount of the release (obtained varying the diameter of the release).