Page 532 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

498 Applied Process Design for Chemical and Petrochemical Plants

Table 7-24
Typical Damage Caused by Overpressure Effects of an Explosion

Uvmprit ,'i1Hf! lp�1)
1
._.__
Equipment ,, s Ill 1' ll) /', � Jl"l'1 ,11) ,,., 110 !-, � t,() I)!, II) l!t "o n � • '.JCJ '.J!,U,I 1]1 114( lhlhHC 1()( '>}I
... ..
- .
-·
C11r,1rr,1 h•i.o .. ., ., c ti 11 ·- -- -I--· -
-.,�ttl ,,,,,t a .. I + .. ,__
Conltf)I "'m""" fl ti I
r:11nr:,�1· ,r,ol
Cor,hnr1 •,)w.,, ·� I ()
T.ink r.r,"" rr,HI ti . le u
ln�tu,rr�I a !Im I
cuh1Cl1t
Fued .,,..,.,, g_ .... , t
Reactor a I i p I
che1T11ca1 I
F,lter h f v - -t
R19t"nen110t I t
hrk. f1011.nq k u d
rcct I
Reacto,. i t
cracimq
P,oe sui::oorts p so
Ut.lor,es eiec- h i t
Irie r,1,,-s'ormer
Electric -ictor h i v
Slower 10 t
Fr1ctton1t1on r t
column
Pressure ·,esseJ pi t
t,or1zona1
S:eaM tc-e.oe i m s v
Heat e .. c ... :1nger i t
Tank SP"' e-e i I t
Pressure .esser i+t
.. e,tical
Puma i-1-- -V
:>0• oo* 1 !014 �17 0·2 1>2•p2a o J o-J5pJBt>-•1p45P·•a D521>55D59 0·62p65 �B!joeJ)c>g 1·1 1 2 1 • i 1 s
Overpressure (bar)
a Windows and gauges break Power lines severed
b Louvres fall at 0.3-0.5 psi m Controls damaged
c Switchgear damaged by roof collapse n Block walls fail
d Roof collapses 0 Frame collapses
e Instruments damaged p Frame deforms
f Inner parts damaged q Case damaged
g Brick cracks r Frame cracks
h Debris-missile damage occurs s Piping breaks
Unit moves and pipes break t Unit overturns or is destroyed
J Bracinc fails u Unit uplifts (0.9 filled)
k Unit uplifts (half-filled) v Unit moves on foundation
By permission, Wells, G. L., Safety i11 Process Plant Design. George Godwin Ltd., London: John Vviley & Sons, N.Y., 1980 (53).

might erroneously be concluded that some fuel-air mix- ingly, the shape of the vessel is an important considera-
ture were "not explodable." For a pipeline of flammable tion when evaluating the explosion potential ofa mixture.
gas/vapor with one end closed and the other open, an All remarks above are related to non-turbulent mixtures,
explosion originating at the closed end will produce a because turbulence increases the violence of the explo-
higher velocity and higher pressure explosion than if igni- sion (Figure 7-58).
tion originates at the open end [54].
The violence of an explosion increases when the shape Figure 7-58 shows the differences in Kc value and max-
of the vessel changes from spherical to a more elongated imum explosion pressures for turbulent and non-turbu-
shape or has a ratio of length: diameter of 1:1 to 1:5, with lent systems for the same fuel-air mixtures.
length several times the diameter due to the flame front
of the explosion moving swiftly in the axial direction and Mixtures of flammable gas/vapors plus oxygen when
compressing at the end of the vessel thereby energizing ignited can form more violent explosions with greater
the violence of the explosion (see Figures 7-56). Accord- peak pressures than when ignited in air.