Flow of a Flashing liquid Through a Pipe
Flow of a Flashing liquid Through a Pipe
(OP)
I'm trying to predict the flow rate of liquid chlorine out of a 90 Ton tanker car in the event of a piping failure downstream of the tanker given the following information:
1. Pipe Size: 1", sch 80
2. Pipe Length: 90' with 12-90 Deg elbows and 3 Valves (1 angle valve at the tanker and 2 ball valves)
3. Tanker car vapor pressure 125 psi.
I have assumed a 1" hole (piping completely cut) to atmoshpere as the worst cast event.
The system we have uses cholorine gas generated by 2 hot water evaporators supplied by the tanker car. No pumps are used. We only rely on the tanker car pressure to force the liquid chlorine into the evaporators.
Any help will be appreciated.
Cotton
1. Pipe Size: 1", sch 80
2. Pipe Length: 90' with 12-90 Deg elbows and 3 Valves (1 angle valve at the tanker and 2 ball valves)
3. Tanker car vapor pressure 125 psi.
I have assumed a 1" hole (piping completely cut) to atmoshpere as the worst cast event.
The system we have uses cholorine gas generated by 2 hot water evaporators supplied by the tanker car. No pumps are used. We only rely on the tanker car pressure to force the liquid chlorine into the evaporators.
Any help will be appreciated.
Cotton





RE: Flow of a Flashing liquid Through a Pipe
What I have used before is
B = (delta P x d^4 / (8.8166 x 10^-6 x K x p))^0.5, where:
B = flow rate in barrells per hr
K = resistence coeffecient (generally 1)
p = density of fluid (lbs/cu ft)
d = inside dia of the rupture (inches)
delta P = pressure differential (psi)
Greg Lamberson
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: Flow of a Flashing liquid Through a Pipe
RE: Flow of a Flashing liquid Through a Pipe
I'm just curious. Are you results based on thermo properties of chlorine?
Typically, it is a straight foward (but tedius) analysis to calculate homogeneous critical flow.
In the nuclear field, research showed that flows higher than that calculated for homogeneous blow down were observed. This goes back to around the early 1960's.
Dr. F. Moody of GE (Not the Moody for friction factors) came up with a steam water blow-down model based on the two phases flowing in an annular flow. This annular flow with slip, resulted in higher than that of homogeneous models but with flows within that actually measured. In fact back in the 80's, the USNRC recommended the the Moody blowdown model be used in safety analysis for line break.
Regards
RE: Flow of a Flashing liquid Through a Pipe
Cotton:
Unless Milton Beychok posts his direct response to your query, I believe the specific solution to your problem is to to to Milton's website:
http://www.air-dispersion.com/usource.html
There, you will see the almost exact application described and the resolution given in a referenced equation. You will note that you are describing a fugitive emission of LIQUID chlorine. The pressurized liquid chlorine will adiabatically expand into a 2-phase mixture as soon as it exits the leakage point. The liquid chlorine emitted will evaporate to form an additional gaseous emission. Milton also gives you the simple equation to determine the amount of liquid and gaseous chlorine initially emitted.
I consider Milton a recognized expert and consultant in this type of emission problem and I would heed what he writes or says.
RE: Flow of a Flashing liquid Through a Pipe
RE: Flow of a Flashing liquid Through a Pipe
dcasto, how did you come up with a flow rate of 10,000 lbs/hr with an eqivalent pipe length of 100ft?
Cotton
RE: Flow of a Flashing liquid Through a Pipe
RE: Flow of a Flashing liquid Through a Pipe
Regards
RE: Flow of a Flashing liquid Through a Pipe
Quite some time ago, I emailed the author about errors, and received no response.
Listed below is the type of info still published on the referenced website.
mbeychok (Chemical) 8 Nov 04 13:00
One important point that is often mis-stated and/or mis-understood:
When a gas flow is at "choked" conditions (i.e., at sonic velocity), the LINEAR VELOCITY IS AT A MAXIMUM. By linear velocity, I mean ft/sec or m/sec for example.
I would like to know the reference for the above ---
since choked flow for any fluid exists when a further decrease in downstream pressure will not result in increased flow.
For a gas, under adiabatic conditions, this is at Mach=1
For a perfect gas under isothermal conditions choking occurs at Mach=1/sqrt(gamma). Clearly for T=constant, velocity is not sonic.
Realistically, conditions are between adiabatic and isothermal,
Regards