Heating Limit of Bunker 'C' or HFO

[MangaMech]

For marine boilers what temperature is Bunker oil brought to before entering the burners. Is there any limit imposed by the equipment used or oil itself. Whats recommended and does practice look to exceed these for better cost/effeciency?
Could any one provide some reference sites to read up on this application?
Thanks in advance

 

[jmw]

Visit

http://www.Steamesteem.com

and the Warsash university diesel engines page

http://www.marinediesels.co.uk

The Chalmers Lindholmen website used to have some useful data but not sure how much is still in the open directory now.


JMW

http://www.ViscoAnalyser.com

 

[mbeychok]

Zymech:

Heating Bunker C or heavy fuel oil (under presssure) to about 700 degrees F (370 degrees C) will cause those fuels to thermally crack into coke which will plug up the piping and the burners.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[TD2K]

Your burner should have some specifications on what the viscosity of the fuel oil should be, I'd start there.

I'll have to see if I have some data in the office on the recommended viscosity, I'm thinking it's going to be 150F or higher to get the viscosity down to a reasonable value.

 

[danberry]

TD2K is right: fuel temperature is dictated by the required viscosity, whish is normally specified by the burner manufacturer. If the fuel varies, so must the temperature setpoint.

 

[21121956]

Hello everybody:

Viscosity is actually not a direct measure of heavy fuel oil quality, but it determines the complexity of the fuel heating and handling system; because heavy fuel oil must be heated to reach a correct injection viscosity in order to have an optimized combustion process in the engine or boiler. Further, heavy fuel oils are typically classed and marketed based on their viscosity.

In order to avoid: too rapid coating or fouling of the fuel oil heaters; the clogging of the fuel injectors tips and the negative influence on the lifetime of fuel injection pumps´s O-rings, the temperature before the injection pumps should not exceed 150º C.

This value is, so far, the adopted in consensus by the engines manufacturers world-wide.

 

[MangaMech]

Thanks all for the posts.
I want to read further on the fuel systems (pumps, meters, burners, and heating) for marine boilers and engines especially when it comes to the use of heavy fuel oils. The demands of the environment especially regarding equipment is of particular interest. Can anyone recommend a web site or publication that gives a solid coverage in part or full?

Any leads appreciated.

 

[jmw]

Visit the IMO and check into MARPOL Annex VI. (a search for MARPOL Annex Vi and search within your results for boilers/burners may take you where you want to go.
There are provisions for COX NOX and SOX reductions which may have some input for you.
I think the MARTOB report on "Onboard Ballast Water Treatment and the Application of low sulphur fuels" examines the necessary fuel systems changes on board vessels in some detail. This mainly applies o the engines but there ought to be some comment on marine boilers also.
Fuel quality is now defined by ISO 8217 2005E. FOBAS and others are very informative on this and you can visit sites such as Viswalab where there are useful comments on marine application of fuels plus also IBIA (International Bunker Industries Association) technical section.
You can visit this link (

http://www.viscoanalyser.com/page8.html)

for a spreadsheet which lets you calculate the injection or EVT temperature for the burners once you know the target viscosity.

Most engines operate between 10 and 20cst but there is an increasing trend from 380cst fuels to 500cst fuels for those who have the equipment to handle the higher temperatures.
For burners it may depend where you draw the fuel from as to your handling temps but for engines the fuel is first heated to around 98degC to drop the viscosity as much as possible without causing the water content to flash into steam before going through the centrifuges and then it goes to the high pressure circuit where it is heated up to optimise the viscosity. e.g., for an MAK type 43 engine the mas allowable fuel temperature is 150degC but for a 380cst fuel the injection temperature is typically 141degC and the optimum viscosity is 11cst. For burners the viscosity allowable may be higher and it will differ for different engines.

Some engines have a fuels envelope that is defined by the viscosity at 100degC, the density at 15degC and the ignition index (usually CCAI values calculated according to BS MA 100).

By the way, if your fuel viscosity lies between the data pre-loaded into the spreadsheet, and you only have the viscosity at one temperature for your fuel, I have another spreadsheet which allows you to infer the viscosity at a second temperature so you can use the spreadsheet you get from that download link. email via the website if you want it.

JMW

http://www.ViscoAnalyser.com