Analyzing flow in a Marine Auxiliary Plant Problem

[NicholasAgius]

Hello,
I have the following problem that i cannot comprehend and understand. I tried searching the internet with no luck on this matter. i am asked to find the Pipe Bore of the system. But i don't have a flow rate for the equation to find the pipe bore.
The Situation is this : Fuel Oil is to be pumped from a double bottom tank to an elevation of 3.8m above a centrifugal pump. the fuel oil vapor pressure varies according to law:

Log Pv = 0.127T - 0.913
where T is the Temperature (degree Celsius)
Pv is the vapor pressure in Bar
the desity of the fuel oil is 880kg/m3 over a temperature range from 50 - 70 degree celsius. the ppump performance is given in the table below and the system is shown in the figure below.
photo (7).jpg

Can somebody help me determine the pipe bore please?

Regards
Nicholas Agius

[JAlberts]

Nicholas, before I give you any further information and references I should advise you to try and find an engineer in your area, hopefully one with piping design experience, to assist you with this issue. Having presented that advice I will give the following comments.

First, on side note, I believe your above Pv formula is in error. I believe the correct form is Pv = Log(0.127T - 0.913). With this revision, the formula gives a Pv = 0.902 Bar, which is consistent with the general specific gravity of diesel fuels.


Beyond that, there are a number of references on the net if you search with the title "piping flow loss"; however, I am afraid many of those are more academic than instructional and will likely simply complicate your search for information. On the other hand, if you want to get an available publication on the subject of piping design I refer you to: http://www.flowoffluids.com/publicat...ne-tp-410.aspx by Crane Fittings Co. This publication in its many editions has served as a reference bible for piping design for over 50 years.

I realize that this document provides a large amount of information to digest but it also covers the elements required for your design. In that respect, you need to realize that unless you intent to dump the fuel from the end of the 1 m discharge pipe end then the piping diagram you provide is insufficient for analyzing the true piping losses of your system and resulting pump capacity. Your analysis must include absolutely every piping section and piping element from the tank intake to the final delivery point of the fuel to be accurate.

Also, what you will find is that all piping analyses start with a required or specified fluid delivery volume and trial piping size(s). From that starting point, then a successive series of trial and error calculations balancing the piping flow losses with the pump delivery curve are made until the piping flow allowed by the piping losses matches the pumps capability to deliver the required volume delivery.

If this seems complicated to you, don't feel alone. These types of calculations are both extensive and tedious even for degreed engineers with a basic educational background in the process. Fortunately these days there are piping design computer programs available and in use in companies that perform them on a repeated basis.

I am not sure if this information is of any real assistance to you but I hope it helps you understand more about the issues related to your problem.

[kriyaa]

Thanks JAlberts for resolve problem.