14 replies to this topic

[applepe]

my supervisor asked me to find the flow rate of the depressurization of pig launcher, pig receiver, and multiphase flow meter. the pressure must be depressurized from 1115 psia to 0 psig and the gas will be released from vent to atmosphere. the pig launcher and pig receiver use 2'' valve and the mpfm uses 3/4'' valve. i use depressuring utility in hysys. the heat flux parameter that i choose was fire api 521 and the type of valve that i used was general valve. the problem was when i run the simulation, the time that it took to depressurize from 1115 psia to 0 psig was so fast maybe under 30 second for all the equipments. one of the mpfm even only took around 5 seconds for it to depressurize. because of that, the peak flow rate was too high and the final temperature was too low. what do you think might be the problem and how can i solve them? im sure i inputed the right composition, condition, and volume of the vessel as my task was just to simulate the data that i got in hysys, but maybe im doing the simulation wrong...

 

for more information this is what i inputed in depressuring utility:

 

volume of vessel: only inputed the value that my coworker already calculated
initial liquid: 10%

discharge coefficient: 0.9
heat flux parameter: c1: 2.100e+04; c2: 0.82; c3: 1

valve area: inputed the size i got from p&id
pv work term: 93%

Edited by applepe, 24 June 2024 - 11:28 PM.

[Pilesar]

I don't know the composition and you have not shown your work, so I will offer some general observations. a) recheck your input. Are your units of measure correct? Is your valve area correct? Ask someone else to verify your input and review your calculations. b ) check the vessel volumes yourself. Ask your coworker for their volume calculations to verify them step-by-step c) do you have reason to disbelieve the depressuring calculation results? Or is it that the results just don't match your expectations? Some depressuring can be very fast. Perhaps the calcs are correct with the flow rate high and the temperature cold. d) Find a verified go-by of a similar calculation. Duplicate that calc and see if you get the same answer that was verified correct. Then you can trust that your methods are good.

Edited by Pilesar, 25 June 2024 - 12:10 AM.

[applepe]

hm so i've already shown my result to my supervisor before i made this post and he said that the flow rate was too high and maybe i made a mistake and that is mostly why i believe that i did something wrong. i will give one of the composition and condition inside one of the pig launchers. this is the every data that i inputed in hysys and the results. (i dont know how to attach picture so im putting the pics in my google drive account.)

 

https://drive.google...mrd?usp=sharing

 

 

I don't know the composition and you have not shown your work, so I will offer some general observations. a) recheck your input. Are your units of measure correct? Is your valve area correct? Ask someone else to verify your input and review your calculations. b ) check the vessel volumes yourself. Ask your coworker for their volume calculations to verify them step-by-step c) do you have reason to disbelieve the depressuring calculation results? Or is it that the results just don't match your expectations? Some depressuring can be very fast. Perhaps the calcs are correct with the flow rate high and the temperature cold. d) Find a verified go-by of a similar calculation. Duplicate that calc and see if you get the same answer that was verified correct. Then you can trust that your methods are good.

[breizh]

Hi,

Check with a smaller valve or orifice.

Let you try the Xcel sheets attached.

Breizh 

Attached Files

•  depressurization Mike beychock.doc   126.5KB   27 downloads
•  Depressurization by Foster Wheeler.xlsx   25.67KB   34 downloads
•  depressurization rev1.xlsx   61.09KB   34 downloads

[applepe]

hi breizh, thanks for your input. i changed the size of the valve into a smaller one and yes it led to a longer depressurization time and lower flow rate. my supervisor agreed with this but he said that now i have to calculate the velocity of the flow to proof if my simulation makes sense or not. so i want to ask another question, does the fluid that goes through vent to atmosphere have a velocity limit? and what if my calculated velocity exceeds 100 m/s? i know fluid in regular pipe usually doesnt even go near 100 m/s to minimize noise and corrotion and does it apply to this case also?

Hi,

Check with a smaller valve or orifice.

Let you try the Xcel sheets attached.

Breizh 

Edited by applepe, 25 June 2024 - 02:15 AM.

[breizh]

Hi,

Check Rho*V^2 criteria  , should be < 150 000 to 200 000 , Rho kg/m3 and V m/s

another one Mach Number < 0.7

Get input from your supervisor and standard at your place .

Selamat Siang

Breizh

[applepe]

that was helpful and hey you speak indonesian haha, terima kasih banyak breizh 

Hi,

Check Rho*V^2 criteria  , should be < 150 000 to 200 000 , Rho kg/m3 and V m/s

another one Mach Number < 0.7

Get input from your supervisor and standard at your place .

Selamat Siang

Breizh

[latexman]

i dont know how to attach picture 

Selamut Pagi.

 

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[fallah]

my supervisor asked me to find the flow rate of the depressurization of pig launcher, pig receiver, and multiphase flow meter. the pressure must be depressurized from 1115 psia to 0 psig and the gas will be released from vent to atmosphere. the pig launcher and pig receiver use 2'' valve and the mpfm uses 3/4'' valve. i use depressuring utility in hysys. the heat flux parameter that i choose was fire api 521 and the type of valve that i used was general valve. the problem was when i run the simulation, the time that it took to depressurize from 1115 psia to 0 psig was so fast maybe under 30 second for all the equipments. one of the mpfm even only took around 5 seconds for it to depressurize. because of that, the peak flow rate was too high and the final temperature was too low. what do you think might be the problem and how can i solve them? im sure i inputed the right composition, condition, and volume of the vessel as my task was just to simulate the data that i got in hysys, but maybe im doing the simulation wrong...

 

for more information this is what i inputed in depressuring utility:

 

volume of vessel: only inputed the value that my coworker already calculated
initial liquid: 10%

discharge coefficient: 0.9
heat flux parameter: c1: 2.100e+04; c2: 0.82; c3: 1

valve area: inputed the size i got from p&id
pv work term: 93%

 

Hi,

 

Didn't you set the time of depressurizing to get the peak flow rate?

Didn't you use any RO after depressurizing valve?

[applepe]

hi latexman, thank you very much for your help. terima kasih!

 

i dont know how to attach picture 

Selamut Pagi.

 

If you are replying, click on "More Reply Options" in lower, right corner of Reply text box.  The file attaching functions are below the new text box.

 

If you are editing a post, click on "Use Full Editor".  The file attaching functions are below the new text box.

 

[applepe]

 

my supervisor asked me to find the flow rate of the depressurization of pig launcher, pig receiver, and multiphase flow meter. the pressure must be depressurized from 1115 psia to 0 psig and the gas will be released from vent to atmosphere. the pig launcher and pig receiver use 2'' valve and the mpfm uses 3/4'' valve. i use depressuring utility in hysys. the heat flux parameter that i choose was fire api 521 and the type of valve that i used was general valve. the problem was when i run the simulation, the time that it took to depressurize from 1115 psia to 0 psig was so fast maybe under 30 second for all the equipments. one of the mpfm even only took around 5 seconds for it to depressurize. because of that, the peak flow rate was too high and the final temperature was too low. what do you think might be the problem and how can i solve them? im sure i inputed the right composition, condition, and volume of the vessel as my task was just to simulate the data that i got in hysys, but maybe im doing the simulation wrong...

 

for more information this is what i inputed in depressuring utility:

 

volume of vessel: only inputed the value that my coworker already calculated
initial liquid: 10%

discharge coefficient: 0.9
heat flux parameter: c1: 2.100e+04; c2: 0.82; c3: 1

valve area: inputed the size i got from p&id
pv work term: 93%

 

Hi,

 

Didn't you set the time of depressurizing to get the peak flow rate?

Didn't you use any RO after depressurizing valve?

 

 i just tried to get as close to 0 psig as i could (i inputed the time by trial and error). and i also didnt use any RO for this case it was only valve

[fallah]

 

 

 

Hi,

 

Didn't you set the time of depressurizing to get the peak flow rate?

Didn't you use any RO after depressurizing valve?

 

 i just tried to get as close to 0 psig as i could (i inputed the time by trial and error). and i also didnt use any RO for this case it was only valve

 

 

Hi,

 

If you are following API 521 method to do the depressurizing study, you should set the depressurizing time also should use RO to control and adjust the depressurizing rate such that having 0 barg (mentioned in your first post) inside the vessel (which is subject to depressurization) just after passing the time was already set.

[applepe]

 

 

 

 

Hi,

 

Didn't you set the time of depressurizing to get the peak flow rate?

Didn't you use any RO after depressurizing valve?

 

 i just tried to get as close to 0 psig as i could (i inputed the time by trial and error). and i also didnt use any RO for this case it was only valve

 

 

Hi,

 

If you are following API 521 method to do the depressurizing study, you should set the depressurizing time also should use RO to control and adjust the depressurizing rate such that having 0 barg (mentioned in your first post) inside the vessel (which is subject to depressurization) just after passing the time was already set.

 

Hi Fallah, i fear i might not understand what you meant about setting the depressurizing time... My goal is to reach 0 psig so thats what i was going for. I didnt set any time or anything i just changed the time until i reached 0 psig. I've asked my supervisor and he said we didnt need to use restricition orifice because we dont need to restrict the flow rate. The fluid will be released to atmosphere. Do you think i should switch from API 521 to another parameter? What do you think is the best for my case? Im a new jr engineer so i only did what i was instructed to do and theres so much thing i dont know 

[fallah]

 

 

 

Hi,

 

If you are following API 521 method to do the depressurizing study, you should set the depressurizing time also should use RO to control and adjust the depressurizing rate such that having 0 barg (mentioned in your first post) inside the vessel (which is subject to depressurization) just after passing the time was already set.

 

Hi Fallah, i fear i might not understand what you meant about setting the depressurizing time... My goal is to reach 0 psig so thats what i was going for. I didnt set any time or anything i just changed the time until i reached 0 psig. I've asked my supervisor and he said we didnt need to use restricition orifice because we dont need to restrict the flow rate. The fluid will be released to atmosphere. Do you think i should switch from API 521 to another parameter? What do you think is the best for my case? Im a new jr engineer so i only did what i was instructed to do and theres so much thing i dont know 

 

 

Hi,

 

Qoute [the problem was when i run the simulation, the time that it took to depressurize from 1115 psia to 0 psig was so fast maybe under 30 second for all the equipments. one of the mpfm even only took around 5 seconds for it to depressurize. because of that, the peak flow rate was too high and the final temperature was too low. what do you think might be the problem and how can i solve them?] Unquote

 

Above statement is selected from your first post and you yourself declared that the peak flow rate was too high hence leading to very low temperature at final and you asked a solution to resolve these problems!

 

Now i repeat my previous advice: if you are intended to lower the peak flow rate hence increase the final temperature, you have to restrict the flow using a RO with a size based on a prespecified depressurizing time... 

[applepe]

 

 

 

 

Hi,

 

If you are following API 521 method to do the depressurizing study, you should set the depressurizing time also should use RO to control and adjust the depressurizing rate such that having 0 barg (mentioned in your first post) inside the vessel (which is subject to depressurization) just after passing the time was already set.

 

Hi Fallah, i fear i might not understand what you meant about setting the depressurizing time... My goal is to reach 0 psig so thats what i was going for. I didnt set any time or anything i just changed the time until i reached 0 psig. I've asked my supervisor and he said we didnt need to use restricition orifice because we dont need to restrict the flow rate. The fluid will be released to atmosphere. Do you think i should switch from API 521 to another parameter? What do you think is the best for my case? Im a new jr engineer so i only did what i was instructed to do and theres so much thing i dont know 

 

 

Hi,

 

Qoute [the problem was when i run the simulation, the time that it took to depressurize from 1115 psia to 0 psig was so fast maybe under 30 second for all the equipments. one of the mpfm even only took around 5 seconds for it to depressurize. because of that, the peak flow rate was too high and the final temperature was too low. what do you think might be the problem and how can i solve them?] Unquote

 

Above statement is selected from your first post and you yourself declared that the peak flow rate was too high hence leading to very low temperature at final and you asked a solution to resolve these problems!

 

Now i repeat my previous advice: if you are intended to lower the peak flow rate hence increase the final temperature, you have to restrict the flow using a RO with a size based on a prespecified depressurizing time... 

 

hi fallah, ok i understand. im going to talk to my supervisor about this suggestion. thank you!!