Explosion Science - morechemistry.com

Transcription

SAFe and Efficient hydrocarbon oxidation processes by KINetics and Explosion
eXpertise and development of computational process engineering tools
Project No. EVG1-CT-2002-00072
Workshop
Saint Dénis La Plaine, November 2006
Explosion Science
Federal Institute for Materials Research and Testing (BAM)
Kai Holtappels
Working Group "Safety Related Properties of Gases"
Division II.1 "Gases, Gas Plants"
1
Outline
History, Trends and Challenges
Beginning of explosion science
Prevention of explosive atmospheres
Ignition of explosive atmospheres
Flame propagation in explosive atmospheres
Protection against the consequences of flame propagation
Final statement
SAFEKINEX - Project Partner
Federal Institute for Materials Research and Testing
Berlin, Germany
Kai Holtappels
Workshop, Explosion Science
2
• The development of human culture is closely linked to the use and
exploitation of fire by mankind.
• Even today more than 90 % of the energy used comes from combustion
processes (apparently decreased in recent decades).
• A remarkably high degree of operational safety has been achieved over
thousands of generations in using combustion processes.
• Of course there is never 100 % safety.
• We occasionally hear of accidental fires and explosions, of combustion
processes running out of control, and of undesired processes that
happen completely unexpectedly.
• Even though their share of the total volume of combustion is generally
very small, their local effects can be disastrous.
• It is therefore truly worthwhile to ensure that such events are avoided.
Berlin, Germany
Kai Holtappels
3
Mining disasters
• The Oaks explosion, Barnsley, Yorkshire, (March 1847): 73 killed
• Courrières mine disaster, Courrière, France, (March 1906): 1099 killed (Worst
mine disaster in Europe)
• Consol No. 9 Mine Mining Disaster, Farmington, West Virginia, USA (1968): 78
killed, 21 survivors (very gassy mine, 200.000 to 250.000 m3 CH4 per day:… a
concrete cap was placed on both shafts….to reduce the amount of intake
air…sustaining the mine fire…November 22 at 2:45 a.m. an explosion
occurred….and blew the cap off the shaft opening. After the concrete cap
blew off, both shafts were filled with limestone….)
• Liaoning mine disaster, Fuxin, People's Republic of China (February 14, 2005):
210 killed
• Sago Coal Mine Disaster, Tallmansville, West Virginia, USA (January 2, 2006): 12
killed, one survivor
Berlin, Germany
Kai Holtappels
4
Consol No. 9 Mine Mining Disaster (http://www.msha.gov/DISASTER/FARM/FARM1.asp)
Explosion 5.30 am
Flames after
explosion (9.30 am)
Concrete cap was blown away
in a second explosion two days
later (installed one day after
explosion)
Berlin, Germany
Kai Holtappels
5
Berlin, Germany
Kai Holtappels
6
Gas explosion disasters
• New London School explosion, New London, Texas, USA (March 18, 1937):
300 killed (natural gas leak)
• Cleveland East Ohio Gas explosion, Cleveland, Ohio (October 20, 1944):
130 killed, one square mile area destroyed (LPG vapour) Refinery in Feyzin,
Isère, France (January 4, 1966): 18 killed (BLEVE)
• Flixborough disaster, North Lincolnshire, England (June 1, 1974): 28 killed
(cyclohexane oxidation)
• San Juan Ixhuatepec explosion, México State, Mexico (November 19, 1984):
500 killed (LPG BLEVE), Petroleum storage facility
• Piper Alpha explosion, North Sea, Scotland, (July 6, 1988): 167 killed (leakage
of natural gas condensate)
• Phillips Petroleum Co., Pasadena, Texas, USA (October 23, 1989): 23 killed
(isobutane UVCE)
• Guadalajara sewer explosion, Jalisco, Mexico (April 22, 1992): 296 killed
(gasoline explosions in a sewer system)
Berlin, Germany
Kai Holtappels
7
Berlin, Germany
Kai Holtappels
8
Berlin, Germany
Kai Holtappels
9
New water pipes, made of zinc-coated copper, were built too close to an existing steel
gasoline pipeline. The underground humidity caused these metals to create an elctrolytic
reaction, which eventually caused the metal to corrode, creating a hole in the pipelines that
caused gasoline to leak into the ground and into the main sewer pipe.
Berlin, Germany
Kai Holtappels
10
Outline
Final statement
Berlin, Germany
Kai Holtappels
11
An explosion can take place only if a reaction can propagate in the
mixture. For the evaluation of the flammability (explosibility) the following
characteristics are used:
•
Explosion limits,
•
Other characteristics of explosion regions,
•
Temperature and pressure limits for instability,
•
Explosion point,
•
Flash point.
Berlin, Germany
Kai Holtappels
12
Explosion limits
Berlin, Germany
Kai Holtappels
13
Explosion limits
First reported explosion limits of methane by Davy (1816, 100 cm3 narrow
necked bottle, top ignition via candle flame):
LEL = 6.2 (burning without explosion) LEL = 6.7 (diminished violence)
UEL = 14.3
History of
methane
explosion limits
Berlin, Germany
Kai Holtappels
14
Explosion limits
Flame propagation
criterion according
to EN 1839,
method „T“
Flame detachment (ignition, height min. 100 mm)
Presentation of
Volkmar Schröder!
Aureole (no ignition, except height of aureole is 240 mm)
Explosionskriterium
Berlin, Germany
Kai Holtappels
15
Explosion limits
fuel rich NH3/air mixture
14,7 mol-% NH3 in air
Berlin, Germany
Kai Holtappels
16
Explosion limits
Newer aspects :
Explosion limits of various fuels in N2O atmosphere (instead air)
Æ follow-on project
Fuel
ammonia
n-butane
ethane
ethylene
carbon monoxide
methane
propane
propylene
hydrogen
LEL (mol.-%)
UEL (mol.-%)
4,4 (15,4)
0,7 (1,4)
1,3 (2,1)
1,4 (2,3)
9,5 (11,0)
1,5 (4,4)
0,7 (1,7)
0,8 (2,0)
2,9 (4,1)
65,0 (33,6)
27,0 (9,3)
33,0 (15,4)
40,5 (32,4)
86,0 (77,0)
45,9 (16,5)
27,0 (10,9)
29,5 (11,0)
82,5 (77,0)
BAM-Annual report 1986
Berlin, Germany
Kai Holtappels
17
Explosion limits
Pressure-time histories of propane/N2O explosions Æ follow-on project
160
160
5,0 mol-% propane
2,0 mol-% propane
140
140
1,5 mol-% propane
1,0 mol-% propane
120
0,5 mol-% propane
100
pressure [bara]
pressure [bara]
120
80
60
100
80
60
40
40
0,0 mol-% propane
20
20
0
0
0
0.5
1
time [s]
1.5
2
0
0.01
0.02
0.03
0.04
0.05
time [s]
Berlin, Germany
Kai Holtappels
18
Other characteristics of explosion regions
Reducing the explosion range by inerting the gas system
0
100
10
90
MOC: maximum oxidizer content
20
80
MXC: maximum permissable
30
amount of combustible
70
40
IAR
MAI: minimum required amount
60
of inert gas
50
fuel
inert gas
50
IAR: minimum inert gas / air
60 [mol-%]
[mol-%]
(oxidizer) ratio
40
70
ICR: minimum inert gas /
30
combustible ratio
80
20
10
0
C
explosion region
90
MAI
100
MOC
100
90
80
60
50
70
40
oxydizer [mol-%]
MXC
ICR
30
20
10
0
Berlin, Germany
Kai Holtappels
19
Temperature and pressure limits for instability
C2H2 decomposition reaction
(1.5 bar, 20 °C, 500 f/s):
pex = 11.7 bara
22
measured pstabat 293.15 K
measured pstab at 373.15 K
simulation: T0 = 293.15 K; TFG = 1454.39 K
simulation: T0 = 373.15 K; TFG = 1458.96 K
19
pstab [bara]
16
Pressure limits of stability for
C2H2/NH3 mixtures at 20 °C and
100 °C (measured and
calculated)
13
10
7
4
1
40
50
60
70
80
90
100
C2H2 [mol-%]
Berlin, Germany
Kai Holtappels
20
Explosion point, Flash point
Scheme of a flash point apparatus
Correlation between explosion limits, explosion points and
flash points: vapour pressure versus temperature
5
6
C
3
8
UEL
molar amount
vapor pressure
D
2
1
7
1
2
3
4
5
6
7
8
Sample (liquid phase)
Sample (vapour phase)
Ignition source
Stirrer
Thermometer reading the flashpoint
Thermometer regulating the heater
Thermostating device
Lid
e
urv
c
e
sur
s
e
r pr
o
p
B
va
A
A
lower explosion point
LEL
temperature
flash point
A = not explosive (to lean)
C = not explosive (to rich)
A
upper explosion point
B = explosive
D = hybrid mixtures possible
Berlin, Germany
Kai Holtappels
21
Explosion point, Flash point
The knowledge of the flash point may lead to a wrong safety impression
due to possible reactions on liquid surface and in foams of bubbles
(Hattwig, Stehen: "Handbook of Explosion Prevention and Protection")
Æ Possible topic for follow-on
Methanol at -20 °C (flash
point at 1 bara: 9 °C,
increases with initial
pressure) and 5 bara O2
Berlin, Germany
Kai Holtappels
22
Outline
Final statement
Berlin, Germany
Kai Holtappels
23
If an explosive mixture is present, the question arises whether it is
ignitable by a certain ignition source or not. For the evaluation of the
ignitability the following characteristics are used:
•
Minimum ignition energy,
•
Minimum ignition current,
•
Autoignition temperature.
Berlin, Germany
Kai Holtappels
24
Examples of
possible
ignition
sources
Berlin, Germany
Kai Holtappels
25
Definition of the
minimum ignition
energy
Presentation of
Max Weiss!
Berlin, Germany
Kai Holtappels
26
Typical blue flames at
ethers:
Ignition of an ether vapor air mixture on a hot surface
(PTB)
Berlin, Germany
Kai Holtappels
27
Determination of Autoignition Temperature according IEC 79-4
3
4
1 Ignition chamber
(Erlenmeyer flask 200 ml)
2 Oven
3 Metering device
4 Mirror
T1
1
T1 Thermocouple reading the
auto ignition temperature
T2 Thermocouple regulating
the oven
2
T2
Berlin, Germany
Kai Holtappels
28
Ignition Temperature / °C
Variation of autoignition temperature with C-chain length
700
700
Hydrocarbons
600
600
500
500
Alkoholes
400
400
300
300
200
200
100
100
Aldehydes
0
0
1
3
5
7
9
11
13
15
17
19
Length of C-chain
Ignition process is strongly dependent on the reaction mechanism!
Æ Presentations of John Griffith and Christian Liebner
Berlin, Germany
Kai Holtappels
29
Outline
Final statement
Berlin, Germany
Kai Holtappels
30
If a combustible mixture can be ignited, the question arises how the
explosion can propagate under given conditions. The following
characteristics describe the reaction propagation:
•Detonation limits,
•Propagation speed of deflagrations,
•Maximum experimental safe gap.
Berlin, Germany
Kai Holtappels
31
Explosion
Deflagration
Detonation
Sf/SS
10-4 < Sf/SS < 3 * 10-2
5 < Sf/SS < 10
Sbehind/Sahead
4 < Sbehind/Sahead < 6
(acceleration)
0.4 < Sbehind/Sahead < 0.7
(delay)
pbehind/pahead
0.98
(slight expansion)
13 < pbehind/pahead < 55
(compression)
ρbehind/ρahead
0.06 < ρbehind/ρahead < 0.25
1.7 < ρbehind/ρahead < 2.6
Tbehind/Tahead
4 < Tbehind/Tahead < 16
(heating)
8 < Tbehind/Tahead < 21
(heating)
Berlin, Germany
Kai Holtappels
32
50-dm3 spherical autoclave designed for pressures up to 1.100 bar
(investigation of detonations)
Berlin, Germany
Kai Holtappels
33
0
10
90
2
N
80
50
l. -
m
hio
c
i
sto
ere -%)
d h ol.
me 69 v
for
is up to
ot
so l.-%
vo
%]
70
ve
ati
n
60
eto
f d ion
o
H2
ge plos
3
ran ex
+
CO
3
->
O2
5
1.
range of
+
6
H
deflagrative
explosion,
3
C
ric
5
bar
abs,
25 °C
t
e
[Vo
[Vo
40
70
O2
l. - %
]
30
50
60
80
(43
st
oi
ch
io
m
et
st
ric
oi
ch
C
io
3H
m
6 +
et
4.
ric
5
O
C
2 3H
>
6 +
3
CO
3
O
2 +
2 >
3
H
3
CO
2O
+
3
H
2O
20
yellow range:
possibly heat
explosion
Different explosion regimes
(deflagration, heat explosion,
detonation)
100
40
30
20
90
prope
ne/air-
mixtur
10
es
100
0
Presentation of
Peter Schildberg!
0
10
20
30
40
50
60
70
Propene C3H6 [Vol.-%]
80
Berlin, Germany
90
100
Kai Holtappels
34
Determination of MESG (maximum experimantel safe gap) according
to IEC 79-1A
6
1 Inner explosion chamber (20 ccm)
2 Outer explosion chamber (2,5 l)
3 Gap
1
4 Window
3
4
2
5 Ignition source
6 Screw
5
Berlin, Germany
Kai Holtappels
35
Maximum Experimental Safe Gap
maximum experimental safe gap
(mm)
3,5
Alkane
Alkene
Alkyne
Hydrogen
Ammonia
Carbondisulfid
3
2,5
2
1,5
1
0,5
0
0
1
2
number of C atoms
3
4
Berlin, Germany
Kai Holtappels
36
Outline
Final statement
Berlin, Germany
Kai Holtappels
37
If an explosion propagates the question arises how its effects can be
estimated. For the evaluation of the effects of an explosion, the following
characteristics are used:
•Explosion pressure and maximum explosion pressure,
•Pressure rise and maximum rate of pressure rise, "KG-value",
•Pressure effects during detonations.
Berlin, Germany
Kai Holtappels
38
Explosion pressure ratios for hydrogen/oxygen and hydrogen/air
mixtures (measured and calculated)
11,0
10,0
9,0
8,0
pex/pi [-]
7,0
6,0
5,0
4,0
BAM 6.0-dm^3 H2/air
3,0
BAM 6.0-dm^3 H2/O2
2,0
calculation H2/air
1,0
calculation H2/O2
0,0
0
10
20
30
40
50
60
70
80
90
100
H2 [mol-%]
Berlin, Germany
Kai Holtappels
39
KG-values for hydrogen/oxygen and hydrogen/air mixtures
(measured and calculated)
4500
BAM 6.0-dm^3 H2/air
4000
BAM 6.0-dm^3 H2/O2
3500
KG [bar m/s]
3000
Presentation of
P. Schildberg
and
K. Holtappels!
2500
2000
1500
1000
500
0
0
10
20
30
40
50
60
70
80
90
100
H2 [mol-%]
Berlin, Germany
Kai Holtappels
40
Examples of constructional measures
Berlin, Germany
Kai Holtappels
41
Pressure venting:
C3H8/N2/air at 1 bara (rupture foil opened at 20 mbar overpressure)
Berlin, Germany
Kai Holtappels
42
Outline
Final statement
Berlin, Germany
Kai Holtappels
43
Final statement
SAFETY
KINETICS
(gas phase) E x p
C1-C3
CVB:
C4-C10
LEL
aromats
UEL
(benzene,
Pmax
toluene,
(dP/dt)max
o-xylene)
MIE
Explosion modelling
eriments
(gas phase)
CVB,RCM, ST: Detailed kinetic
IDT
AIT
CFT
ISC
modelling
C1-C3; C4-C10
aromats
Validation / Reduction
Many aspects (trends, challenges…)
have been combined in
Data base the SAFEKINEX-project.
Reactive flow
+Prediction
Comp.Fluid Dynamics
Flow Explosion Tests
of explosion indices
Industrial Application
Process safety, Engineering, Process control
Berlin, Germany
Kai Holtappels
44
Final statement
Important trends and challenges not presented:
• vapour cloud explosions and their consequences
• quantitative risk assessment of explosion hazards
• Security (terrorism)
• modeling (reactive flows in closed/confined/open
spaces, safety characteristics, kinetics)
Berlin, Germany
Kai Holtappels
45
Final statement
… The way we blind ourselves to honest assessment of
risk goes back a long way. …
… As individuals, we may learn from close shaves and
warnings; as a society, we only learn from blood. …
Risk Management and Technology by Roy Brander, Calgary, Alberta
Presentation to the National Defense Industrial Association Conference,
Vancouver, 29 February 2000
Berlin, Germany
Kai Holtappels
46
Thank you very much for your attention. If there are
any questions left don`t hesitate to ask me.

Explosion Science - morechemistry.com

Transcription

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