14 replies to this topic

[deepakrraj]

Dear all,
Is there any Nozzle Criteria for Atmospheric Storage Tank Inlet Nozzle?Because we planned to increase pumping in capacity to the floating roof storage tank.As per the revised flow rate the Rho v² becomes 43000.Its acceptable?

[ankur2061]

deepakrraj,

Please refer the link below for an answer to your query:

http://www.cheresour...-nozzle-sizing/

Regards,
Ankur.

[deepakrraj]

Thank you Mr.Ankur Srivastava.But in the topic its not clear about the maximum acceptable rhov² .Please clarify me....

[ankur2061]

deepakrraj,

I have no means to qualify the rhov² value of 43,000 as acceptable or not. Post # 4 in the link provided in my response to you mentions that momentum values are not critical since there is less or insignificant concern related to separation of phases, liquid entrainment & mechanical vibration due to large open area of discharge inside the tank.

Momentum values are very well defined for two-phase and 3-pahse separators for 2-phase flow in Shell Design Engineering Practice DEP 31.22.05.11-Gen.

I guess that if you are faced with high momentum values you could increase the inlet nozzle size by one or two sizes bigger than the inlet pipe size.

Ultimately the static mechanical engineer will have to make a decision on how to strengthen the nozzle e.g providing truss support to the nozzle in case the momentum values are unavoidably high.

Regards,
Ankur

[deepakrraj]

Dear Mr.Ankur Srivastava the problem is we experience noise in the nozzle area.Before that rhoV² is about 10000.After the flow rate was increased we experience some problems.

[S.AHMAD]

Dear Raj
1. Is the inlet nozzle equipped with "diffuser"?.
2. If not, diffuser shall be helpful in reducing the noise level.
3. If yes, then ensure that the velocity per slot is 1 ft/s or less otherwise increase the number of slots e.g increase the length of the nozzle diffuser accordingly.

[deepakrraj]

Dear Mr.Ahmad,
1.The inlet nozzle is not provided with diffuser.
2.We plan to provide two inlets to the tank.Its advisable?

[jrtailor09]

Deepakraj,

You are increasing the inlet flow rate so, Outbreathing rate is also increse accordingly.
Please do check your existing PVRV size also whether existing valve able to take care revised flow rate as per API 2000.

For others :

I felt that rhov² value usually check for two phase line. Is it aplicable for single phase line also ? Please inform & correct me.

Regards,

Jatin

[deepakrraj]

Dear Mr.Jatin
1.This is floating roof tank.
2.Sorry. i have no idea about Rhov² criteria.

[S.AHMAD]

Dear Raj
1. Reducing the velocity through the nozzle is the right direction.
2. Increasing the number of inlet nozzle certainly helpful in eliminating the noise since noise is normally related to vibration induced by high velocity.
3. If room is available, install the nozzle in opposite site. This will improve mixing.

[deepakrraj]

Thank you Mr.Ahmad.
1.We planned to provide another inlet through spare nozzle available near by the existing nozzle.

[jrtailor09]

Deepakraj,

Sorry, I have not noticed floating roof tank.

Please do check your Size & No. of bleeder vent.This is also depend upon the inlet & outlet flow rate of tank because in your case inlet flow rate is increasing.

Rest all member

Regarding Rhov² criteria please give your suggestion.

Regards,

Edited by jrtailor09, 13 May 2012 - 04:59 AM.

[vikramltv]

Dear jrtailor09
as per my company standered mixed flow line have rho*v2 criteria as 14900 for continous services and 23300 for intermittent service..and this criteria is also accepted by many process licensors..

[vikramltv]

Dear jrtailor09
as per my company standered mixed flow line have rho*v2 criteria as 14900 for continous services and 23300 for intermittent service..and this criteria is also accepted by many process licensors..

[deepakrraj]

Dear Mr.jrtailor09,
Thanks.I forget to check that.Bleeder vent only comes in line when the floating roof reaches the maximum level or minimum level...... right?