Heavy Fuel Oil Delivery

[kimawi]

Hi All,

We are operating a "small" burner (~400 kW) on Heavy fuel oil #6. The oil tank is heated to 110C and the pipe delivering the fuel to the burner is electrically traced and insulated. Our problem is that we get a very unstable and pulsating flow of oil to the burner which affects the flame stability. We watched the oil flow right after the pump (into a drum) and was stable, the instability comes from the piping to the burner (about 20 m). The pipe was originally designed for a much bigger burner and hence is oversized (half Inch pipe for 35 L/h oil) but not sure if that can cause all this instability, seems like some gas or air comes out with the oil and causes this pulsation on the burner end. Would a smaller pipe help solving the problem? The pump suction is right at the bottom of the tank, I can't see how any air can get into the system.

Thanks

 

[TBP]

I seriously doubt that the piping is the issue. How is the oil being atomized?

 

[kimawi]

TBP,
The oil was atomised with a twin-fluid atomiser and we suspected at some stage that the atomising nozzle is the problem. Well, we disconnected the nozzle and throttled the flow with a valve and the flow was still pulsating.

 

[TBP]

What kind of pump are you running?

 

[kimawi]

It's a rotary screw pump.

 

[TBP]

Most of the applications like yours that I've worked with, have used gear pumps. I can't actually recall ever seeing a screw pump in bunker oil service. Is your problem the pump?

 

[jmw]

Have you checked the water content of your fuel?
Is it homogenous?

JMW

http://www.ViscoAnalyser.com

 

[rmw]

Is there anywhere where the oil supply piping is next to or touching very hot parts of the device that has the burner? With a velocity that low, it would have plenty of opportunity to heat further.

Also, why are you heating to 110C? Would a lesser temperature get your oil to the burner?

What is does your #6 consist of? Is it true #6 or is it some nasty heavy something or the other (think asphalt) cut with some light something or other to make it similar to #6? If it is the latter, which is fairly common in #6 these days, then what ever the lighter component is might be off-gassing before or in the burner tube.

rmw

 

[kimawi]

Sorry Gentlemen,

Nitrogen used for purging was leaking into the oil line via a faulty ball valve, problem solved.

Apologies for the confusion.

 

[jmw]

Thanks for that Kimawi, I for one can add that to the list of things to look out for that I didn't know before and all too frequently we never hear the outcome of some of the problems posted so it is satisfying to know that a problem has been solved (however it was solved).

JMW

http://www.ViscoAnalyser.com

 

[MJCronin]

I agree that this problem sounds like it is not associated with the piping size or configuration.

Just to be sure, a "pulsation dampener" could be installed on the pump suction. It may help....

If you decide that this is worth a try (modest expense) I would be sure to confirm with a vendor that component materials are acceptable (No. 6 is slightly corrosive to elastomers)

Good luck.......let us know of your final solution...

-MJC