8 replies to this topic

[Pouya79]

I am trying to simulate tube rupture case in Hysys Dynamic. Has anyone tried this before?
I assumed NG is the medium in high pressure side of the HX with 5600kpaa and 0C (tube side) and Glycol is in the shell side with 1035 kpaa and 150C.
Another assumption is the Glycol mixes with NG in the mixer and then splitted in two pathway, one is the PSV and another is the shell outlet.
Can I activate the flow spec instead of pressure spec? I tried to do this however, Hysys did not allow me to proceed and automatically changed all boundry streams to pressure spec.
Thanks

[AlertO]

hi pooyishka

This sounds interesting because i've never performed the tube rupture calculation on hysys dynamic simulation. However, you can try, but not forget to be compared to simplified calculation method i.e. the two-orifices.
The boundary spec is the most important during dynamic simulation which normally can be flow or pressure spec, but pressure spec is more common in use.
For your problem, i can not give you exact solution due to too less information.

[Pouya79]

Thanks in advance for your quick response. Please follow my topic, I will upload my simulation by tomorrow.
I will be greatful, if you help me how to swtich from pressure spec activation to flow. I think the model I simulated is not that much far from reallity, however I do not know how much hysys dynamic can help to see the pressure transient wave.

[Pouya79]

I attached an snapshot of my simulation. Please give me your email and I can send you the Hysys file.

Attached Files

•  HYSYS-Print.pdf   39.34KB   249 downloads

[AlertO]

dear pooyishka

my email address is lert_mynet@hotmail.com

[AlertO]

Dear Pooyishaka

i have reviewed your model and if there is no error with input, the overall are fine because all pressure boundaries are specified and all device has been sized. So, i will ask you more as the following questions:

1. you mention about flow specification. which stream you mention and why do you want to spec the flow rate?

2. Does VLV-104 is PSV? if yes, you should use the safety valve item from hysys instead.

3. and the final one (most important), how will you generate the tube rupture scenario into your model? i've never done before and have no idea now. please share your idea how to do it. This is the most important which will tell you that if you can use HYSYS-dynamic to find the relief load.

looking forward to hearing from you.

Edited by AlertO, 06 March 2014 - 02:42 AM.

[Pouya79]

Hi,

 

Below is my reply to your questions:

 

1- I was about to switch the pressure spec to flow spec for stream "NG Injects ...", in order to keep the flowrate constant ( to dictate the tube rupture flow rate to my simulation from that point) and then trace the pressure wave in my system. However, I think it is better that I use pressure spec in my boundaries to get more stable and reliable simulation as I searched in the internet. It is a little bit tough for me to understand and touch the concept of Pressure Spec. and Flow Spec.

 

2- Yes, Valve-104 is the PSV. I do not know how to use the PSV in Dynamic model. I tried to put PRV from Object Panel but I could not to solve it. If you help me on that I really appreciate that.

 

3- If you insert a pressure of 2000 kPa in stream "NG Injects..." and wait to get system stabilized and then change the pressure to 5600 kPa and trace the pressure wave by stream 6 and 15, you will see the time that wave reaches to those streams and how much delay you have. This is just a primary idea and I am trying to find the better way to define this scenario. Actually I am not able to insert this pressure shock directly to the heat exchanger, however the Pipe-101 is a 24" pipe with 8 m long which is the dimensions of HX shell. In fact this pipe is the volume of shell which is pressure shock goes inside.

 

I could not find any answer these question:"Does hysys consider this sudden pressure increasing as a pressure surge and shock wave or not?"

[AlertO]

hi

See my more explanation to your points below.

1. Flow spec is used when your source can maintain the flow even though the higher pressure in the boundary. If not, pressure spec is proper to be used.

2. Only three parameter you have to input: set pressure, full open pressure, and prelim. orifice size (no need the actual size at the begining).

3. the change you have mentioned doesn't reflect the tube rupture scenario. as i mention, this is the most important. if you cann't create the proper scenario into the model, you cann't find the relief load from this file. The manual model with a series of mathematics like CFD will be used if you still want to do on dynamics.

4. Yes, hysys-dynamic is applied to find the sudden pressure change in abnormal scenario i.e. the surge line of the compressor. however, i'm not quite sure the word " shock wave" you mentioned.

[joshimanan01]

Tube ruputre is now available in HYSYS 8.4 and later version.  Just try to check.  I am confuse about the properties it considered. please if any one can highlight on it.

Manan