Pressure Surge in Fuel Oil/Diesel Pipeline

[ryonan]

Dear all,

First, some background info:

To improve the quality of product in our plant, fuel oil and diesel are mixed together using different portions eg 85:15, 93:7 etc.
The fuel oil is pumped at 3600 l/min while the diesel at 1800 l/min via centrifugal pumps.
The two products then simultaneously go into a mixing/blending pipeline (abt 2 metres long) before going into lorry tankers etc for delivery.
The amount of fuel or diesel that goes into the mixing pipeline are controlled by actuated control valves (butterfly).

However we suspect that the the pumps have been over designed. Not much problem for the fuel oil since the portion required is quite large (more than 85%). But the instantaneous opening and closing of the valves controlling the amount of diesel going into the mixing pipe creates a pressure surge, transferring the force even to the loading bay structures causing it to vibrate most rigorously.

Can anyone suggest any good and economical solutions to stop this?
Thanks!

ryonan

 

[TD2K]

I doubt the problem is the sizing of the pumps, it's your 'instantaneous' opening valves (or very fast) that is creating the water hammer.

I was in one bulk terminal and they had essentially expansion devices to control water hammer and it sounds like they had a similar setup to yours. Essentially, problem is that when your valves slam shut, the liquid being essentially incompressible experiences very high pressures as the kinetic energy (velocity) is converted to potential energy (pressure). The expansion vessels contain gas (frequently separated from the liquid by a bladder) and dampens the pressure wave. They are analogus to pulsation dampeners on PD pumps.

 

[Scipio]

I agree with TD2K. No pump is built to discharge against instantaneous valve operation, I think your problems are cause by the rapid change in velocity of the diesel. Same as water pipes sometimes hammering if you turn off the tap too quickly. I also agree that a surge stabilizer is the way to go, or alternatively modify your proportioning valves so they throttle the diesel flow rather than just operate on/off.

 

[stanier]

Try

http://www.charlatte.com.

They make a range of surge arrestors for yoiur application.

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