DP

[padovano]

I would like to know to what extent the pressure difference between atomization steam and fuel in a fuel oil gun can be increase. I discovered recently that, the pressure of fuel oil fluctuates between 6-8 bars. The present pressure difference is 2 bars. I intend to raise it to 2,5 bars. I believe it will cause the fuel oil to burn more efficiently. I would like to know if the would be any consequences.

 

[rmw]

The oil flow through the gun tip is a balance between oil pressure and atomizing steam pressure. If you raise the atomizing steam pressure it may well help the atomization of the oil, but the increased pressure can reduce your oil flow. If you have all the guns in, then that will affect your unit load-you may have a better fire, buy you will end up with reduced load. If you can add guns, them it might be the right thing to do.

rmw

 

[786392]

Even there may be increased possibilities of Flame-out; although might not be usually envisaged.
Around 1.5~2.0 bar delta P is considered most usually practiced as per the burnt Fuel Viscosity and other fluidity related considerations.Hope this helps.

Best Regards
Qalander(Chem)

 

[padovano]

so there is no benefit in increasing the delta P?
I taught by doing so, I would reduce flame lenght and also reduce the drooling of fuel oil along the fuel oil gun.
Any light on these views?

 

[jmw]

What type of oil? is it a heavy fuel oil?
If so, have you got viscosity regulation of the heaters?

JMW

http://www.ViscoAnalyser.com

 

[rmw]

If you are 'drooling' fuel along the gun, your steam atomizing pressure might not be up to what it is supposed to be. If that is the case, raising it would help. If it is already where it is supposed to be, raising it will result in what I stated above.

If it is what it is supposed to be, check your steam piping to make sure it is trapped properly. You might be getting moisture in your steam and that isn't helpful.

Also, your gun tip pieces/parts might be worn out. Have you checked them lately? If the steam holes are gone or plugged, or oil passages are plugged or worn so that they are open more than designed, your gun will 'drool' (dribble) oil out the tip.

For an oil burner of any type, steam or mechanically atomized, the tip components need to be top notch and burning heavy oil is tough duty even on some of the hardest materials known to man.

rmw

 

[rmw]

And, speaking of the which, when I clicked out of this thread, I noticed that the next thread in the line by RCRom is on the topic I just touched on. That would be a good read for you.

rmw

 

[padovano]

Thanks for your various views.
The fuel oil is heavy fuel. Viscosity at 50°C is 126mm2/S.
I will check the orifices of the burner tips as rmw surgested.

 

[jmw]

So, how do you control the viscosity?

What you are seeing might also be due to poor heater control resulting in the viscosity not being optimum (or it in turn can help degrade the nozzles if the viscosity is too high).

If the oil is to thick or too thin you will not get good performance. If it is too thin then you may get a fine non-dispersive mist around the nozzle and if too thick the fuel will be projected in large slower burning drops right through the optimum burning zone.

A common approach to dealing with heavy fuel oil is to make frequent samples and lab analysis to determine the EVT (Equi Viscous Temperature) i.e. the temperature at which the viscosity is optimum (but which may change unexpectedly due to fuel oil quality changes) and use temperature to control the fuel heaters. This is accompanied by excess oxygen flow to try and ensure more complete combustion, and visual flame inspection.

An online viscometer automatically respond to changes in oil quality and viscosity by controlling the heating to maintain the optimum viscosity.

The benefits are that excess oxygen can be reduced which can lead to significant cost benefits, the fuel is burnt more efficiently which brings better economic efficiency but also less pollution and less soot blowing, and lab testing becomes far less critical.

This is an article about what used to be Huntsman Chemicals... no idea what they are called now...

http://www.engineeringtalk.com/news/slm/slm106.html

JMW

http://www.ViscoAnalyser.com

 

[786392]

Dear padovano Hello/Good Afternoon,

Options to check/explore for rectification include, but not limited to the following.

Check Fuel Oil system strainers Main Pumps/Local near each burner,manifolds.

Check/ Ensure as per requirements Fuel Oil viscosity blend and maintain its temperature within the limits;not lower.

Check ensure as per requirements atomizing steam temperature and pressure within the limits;not lower.

Also Check/Ensure various control instruments to maintain Fuel Oil header pressure& desired DP for Atomizing steam VS fuel oil.

The above should trouble-shoot 'drooling' at burner gun tips and must help the way forward indeed!

Best Regards
Qalander(Chem)