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Optimization of water sprayer characteristics

Objective



Water sprays are used extensively in the petrochemical
exploration, production and processing industries both onshore and offshore to mitigate the effects of fire on equipment and structures. This can be achieved in several ways, for example by extinguishment of the fire, by cooling either the fire or the surface to be protected, or by providing a protective curtain to absorb radiative heat flux. Fine water sprays may also have
potential for explosion suppression.
Failure to provide adequate protection in the event of fire could lead to loss of life, structural failure or damage and loss of containment of hydrocarbon products with an accompanying
pollution risk.
Regulations governing the use of water sprayers are relatively general. It is usual for rules to specify only the surfaces to be protected, the minimum water application rates and the length of time protection is required. These application rates are
likely to have been based on limited experimental results and "engineering experience".
Although the use of a spraver may be characterized by a water application rate, the effectiveness of the sprayer depends also on the water droplet distribution and on the fire scenario
involved. For some situations the droplet must be of sufficient size and velocity to penetrate and cool the fire plume. In
others droplets should present a large surface area to absorb radiation. Size and velocity of droplets are important in any situation where wind may be present.
The aim of this proposal is-i) to determine optimum droplet size and velocity distributions as well as mass flux for protection from a number of fire scenarios likely to arise in the
petrochemical industry and ii) to relate these to the physical characteristics of the water spraying device. It should then be possible iii) to design and prototype an efficient sprayer with these optimum characteristics.
In order to accomplish these objectives a combined theoretical and experimental programme of work is needed.
A major part of the programme of work will involve an analysis of the way in which water sprays interact with various selected scenarios. This will be done theoretically by examinining droplet ballistics, heat transfer and cooling processes and
experimentally, following construction of a device to produce droplets of a variable but specifiable size and velocity, by examining the interaction of such droplets with small scale
fires. Information at this basic level will be invaluable for assessing the performance of existing water spray devices, and also for providing a sound technical basis for the future
development of regulations for water spray protection. The
information will also be used in the second part of the work programme in which the water spray characteristics will be
related to the physical characteristics of the spray devices and a spray head producing the optimum droplet characteristics
designed and prototyped.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bertin et Cie S.A.
Address
Avenue Du 1Er Mai Zone Industrielle
40220 Tarnos
France

Participants (1)

Itsemap Fuego SA
Spain
Address

28034 Madrid