Mixing of flashing water with cold water
Mixing of flashing water with cold water
(OP)
Case description:
Saturated brine (9 bara) is flashed (5 bara) over a valve. The two phase fluid is than mixed with cold brine (<100oC) discharged from a heat exchanger.
What we see (or hear) on field are heavy and noisy bumps that seem close to take the pipe out of the concrete.
1. Are there any flow elements that can help with that kind of mixing?
2. Are there any rules of thumb for the upstream minimum length for the two phase before it mixed with the cold fluid?
3. Any reference/paper deals with that kind of mixing?
4. Any good field experience?
Thanks
Saturated brine (9 bara) is flashed (5 bara) over a valve. The two phase fluid is than mixed with cold brine (<100oC) discharged from a heat exchanger.
What we see (or hear) on field are heavy and noisy bumps that seem close to take the pipe out of the concrete.
1. Are there any flow elements that can help with that kind of mixing?
2. Are there any rules of thumb for the upstream minimum length for the two phase before it mixed with the cold fluid?
3. Any reference/paper deals with that kind of mixing?
4. Any good field experience?
Thanks





RE: Mixing of flashing water with cold water
Best regards
Morten
RE: Mixing of flashing water with cold water
RE: Mixing of flashing water with cold water
It will be not responsible to say that I am sure that it is not from the valve. The all line was taking the bumps and the valve is very close to the mixing point. It is very hard to identify if the bumps are from the valve or from the mixer. For the mixer, and that goes for RustBuster as well, we use common mixer with the cold fluid line is inserted in the main line tangentially.
My questions to you still stands.
RE: Mixing of flashing water with cold water
RE: Mixing of flashing water with cold water
Tell me if you need a draft.
RE: Mixing of flashing water with cold water
But to test my other theory about the noise comming from the valve you would only have to turn of the cold water for a while - if possible. Then the noise should move "downstream" the cavitation coming later due to slower cooling.
Best regrads
Morten
RE: Mixing of flashing water with cold water
The mixing should be done inline so vessel is not applicable.
I will try to arrange a test to check IONE and MORTENA suggestions.
For the sake of good practice, let's consider the following options:
1. Flashing the saturated fluid on a valve and enlarging the pipe so the flow will become annular (assuming enough straight run). Than injecting the cold fluid.
2. Same as one but not enlarging the pipe to allow dispersed flow for better mixing.
3. Injecting the cold fluid just after the flash valve to avoid two phase flow regime development.
After deciding on the best location what is the best way:
1. Type of mixer.
2. Inject the cold fluid from bottom/side/top of the line.
Further information that I dropped is that the cold and saturated fluids flow is similar (by weight) and lines are 12".
RE: Mixing of flashing water with cold water
Good luck,
Latexman
RE: Mixing of flashing water with cold water
[quote]close to take the pipe out of the concrete[quote]
I have to admit that the phenomenon theorized by rustbuster and Latexman is very likely to happen (kudos to them). It is defined as condensation induced waterhammer. Condensation promoted by cold brine and flashing brine mixing is associated with a fast volume reduction. Consequent depressurization leads to voids formation, which are rapidly replenished by the liquid phase. The resulting collision of liquid phase provokes surge.