4 replies to this topic

[navneet2109]

MAJOR POINT

 

1. Is FT is necessary to control the flow of fluid in recirculation Line as pump flow is constant?

 

2. Could we use Spherical tank Level to control the recirculation Line through level transmitter on the tank? if yes why and how?

 

3. If PG is fix at discharge then it should be before check valve or after check valve?

 

Other points

 

 a)  somebody suggest me to Use pressure transmitter instead of pressure gauge so that we use pressure of pump discharge to control the recirculation line?

 

   Its also suggest me that i should take resirculation branch before check valve so that it will be easy for commisioning purpose and second point is that pump need stablisation first so that it will reciculate the all fluid at start after stablisation of pump we open the isolation valve for further step.

 

Your suggestion required if other thing comes after your study of this PFD. Please

 

 

Regard Navneet

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•  LPG Storage tank unit Questions.txt   877bytes   14 downloads

[shvet]

 

 1. Is FT is necessary to control the flow of fluid in recirculation Line as pump flow is constant?

 

 

Yes. It is called min continious stable flow and pump shall be protected to prevent pump damage and/or leakage. Especially LPG pumps. See 3.28 and 3.29 terms in API 610 for more information.

 

 

 

2. Could we use Spherical tank Level to control the recirculation Line through level transmitter on the tank? if yes why and how?

 

 

No

 

 

 

 3. If PG is fix at discharge then it should be before check valve or after check valve?

 

 

Before. See fig. B.3 API 686 for more information. Anyway pressure gauge connection should be located no less 2D from any flow disturbancies - discharge flange, valve or reducer.

 

 

 

 a)  somebody suggest me to Use pressure transmitter instead of pressure gauge so that we use pressure of pump discharge to control the recirculation line?

 

Pressure transmitter - yes you can. But do you actually need pressure transmitter instead of pressure gauge?

 

Use pressure transmitter to control flow - no. It will not work. You can use this for pump safety trip if there exist such vendor's requirements.

 

 

 

  Its also suggest me that i should take resirculation branch before check valve so that it will be easy for commisioning purpose and second point is that pump need stablisation first so that it will reciculate the all fluid at start after stablisation of pump we open the isolation valve for further step.

 

 

No. It will not work. If you want to use individual min flow line for each pump you can use schroedahl valve. It works in the same way as FC valve in your PFD.

 

Your PFD seems to me rather conservative but reasonable. Don't change it.

[ankur2061]

Navneet,

 

I have presented several schemes for minimum continuous recycle flow for centrifugal pumps with notes stating their salient features including advantages / disadvantages. You may find them useful for review and selecting the right scheme. Refer the link below:

 

http://www.cheresour...trifugal-pumps/

 

Regards,

Ankur.

[navneet2109]

To, 

Ankur sir & shvet

 

Thank you to both for your reply

One more question related to this project but a little different topic.

 

What is the difference between Remote Operated Valve (ROV) and Motor Operated Valve ( MOV) ??

I need some detail on this.

 

What I know is MOV is particular only for electrically actuated but ROV can be used for Pneumatic, Hydraulic & Electrically. I have read recently in forum (http://www.eng-tips.....cfm?qid=392317) (http://www.eng-tips.....cfm?qid=232259) MOV doesn't have Fail-safe Provision.

Edited by navneet2109, 09 July 2016 - 12:51 AM.

[fallah]

Navneet,

 

In general, MOV is a valve used as an isolation valve for equipment need regular access in which the actuator part of the valve is replaced by a motor mostly due to high required torque not to be provided by pneumatic actuator. Hence, MOV is usually applied in big line sizes for on/off conditions mostly due to more ease of operation than the ordinary on/off valves.

 

Remote operated valve is another story and is normally a shut down valve can be closed remotely in the case of an emergency condition.