Simplified vent sizing methods incorporating two-phase flow

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:255381

Leung, J C ^[1]

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1. Fauske & Associates, Inc., Burr Ridge, IL (United States)

Venting requirements for both reactive and non-reactive systems are reviewed here with particular reference to multiphase discharge and runaway reactions. Runaway reaction systems can generally be classified as tempered or non-tempered types. A tempered system is one in which the reaction heat can be removed by latent heat of vaporization, thus controlling the runaway reaction from escalation in temperature. This of course is accomplished by pressure relief venting. Many of these systems are in fact normally operated in the refluxing mode for temperature control. The latent heat can be provided by either the reactant(s) or the solvent(s). However, the latter case presents special concern if the system loses its solvent via boil-off due to fire. Note that a tempered system can accommodate a reaction that gives off noncondensable gases as long as the reaction temperature can be controlled is called a tempered hybrid system. On the other hand, a non-tempered system exhibits little or no latent heat of cooling at all; this is typical of a low vapor-pressure system (or high boiling point compound). If the reaction products are also of low vapor pressure, the pressure relief requirement can be quite small. But quite often the reaction product(s) are noncondensable gas(es), these are so-called {open_quotes}gassy{close_quotes} systems. For these non-tempered systems, the heat release is largely retained in the runaway reaction mass and if left unattended, without cooling re-initiation, quenching or dumping, may lead to very large temperature and pressure excursions. As might be expected, the vent sizing methods differ depending on the system type. 39 refs., 17 figs.

• OSTI ID: 255381
• Report Number(s): CONF-9508216--
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CALCULATION METHODS
CHEMICAL EXPLOSIONS
CHEMICAL EXPLOSIVES
CHEMICAL REACTIONS
PRESSURE RELEASE
SIZE
TWO-PHASE FLOW
VENTS