Accelerated wear of burner gun tips - Bunker c fired furnace 4

[RCMRon]

What would cause accelerated wear, 4 to 5 times normel wear, on burner gun tips/nozzels? We have bunker c heated to 285 deg F going into a flame fried pelletizing furnace. Burner gun tip materail is consistent.

 

[ash9144]

Have you recently changed the tips? When was last time orifice sizes of tips were measured?

If it is consistent to all tips it sounds like a fuel issue. Maybe some solids or some chemical contaminant.

 

[rmw]

Are you sure that the tips you are using as replacements are of the material that you think they assuming that you are going for the premium materials.

rmw

 

[athomas236]

Have the tips that wear excessively always worn excessively or is this just a recent occurence?

Regards,

athomas236

 

[RCMRon]

All tips, 96 of one type from 3 different manufacturers and 48 of another type are all wearing prematurely since about aug/sept 2008. We have just compiled the oil analysis of our buncker C shipments and to the untrained eye there doen not seem to be an disturbing trends but it may be an interaction of various chemicals/metals. We have also noticed sludge build up in the final filters. Previously we would change the screens on a weekly basis and any minor buildup was removed by waching in a solution. No the build up is like a thick grease and has to be scraped off and a wire brush used. One type of tip that has ben in operation for over ten years has never word before and now they are wearing also.

 

[786392]

Have You Changed Bunker C source recently?

Have you got the 'present Bunker C in use' analyzed for metal contents and any variances from original Specs?

Did you check-out the gum formation tendency in the storage(s) or has the storage tanks temperature raised recently?

Have you any damage to storage tank roof; thereby excessive air in-contact with heated stored fuel?

Has there been excessive water contents or asphaltic residues and/or cracked materials in the present bunker C in use?

Similar queries need to be answered for problem solving.

Moreover any change(s) recently might be very un-important should be traced back to find out the issue root cause(s).

Best Regards
Qalander(Chem)

 

[RCMRon]

Once again thanks for the great feedback.

Since the spring of 2008 we are single sourced out of one refinery whereas it used to be 2. That information as to which chipment came from which refinery is in the process of beingh tabulated and cross referenced but i don't have it yet.

All of the bunker C analyses for metals etc we have and none of them seem to exceed specs but I would question the validity of our specs, is Vanadium in the 200 to 300 PPM range normal? the gum formation tendency and temperature raise of the tansk has not been chacked but i beilieve it is constant. How would I do a check for gum formation tendency?
In terms of water, asphaltic residues or cracked material, all we have are the oil analysis reports which report the condition of the oil at our port and not necessarily in our tanks. i will have the integrity of the tanks verified. Is the asphaltness test an indicator of getting asphaltic residues or is it a test that can be perfomed with the insitu bunker C in our tanks.

 

[786392]

I understand Vanadium Contents beyond 30~45 ppm are not advisable.

Also the Calcium contents on the higher side indirectly indicate overall higher vanadium contents.

Cracked material or some asphaltenes presence do increase gum forming tendency.

Water contents do initiate bacterial growth and also create bacterial strains with polymerised and oxidised material agglomerates.

All these may impart sludge and sediment increases and consuquently may lead to the situation indicated by you as the worst case indeed.

Best Regards
Qalander(Chem)

 

[RCMRon]

I have queries in progress as per your previous suggestions of what i should be looking for.

What exactly is Cracked material, how would you check for it and how would you see the presense of ashpaltness?

is 30 to 45 PPM a normal specification that we could get from Bunker C?

I am told the as little as 50PPM of vanadium can harm refrctory. We had a refractory failure a few months ago.

thanks for the great input and suggestions. I believe i am being steered in the right direction.

 

[jmw]

Any recent changes/maintenance to any equipment in the fuel supply line... oil heaters, perhaps?

JMW

http://www.ViscoAnalyser.com

 

[786392]

As 'JMW' suggested check the issue thoroughly.

The 'change' might be apparently unrelated; still trace for any changes.
e.g. any of the strainer's mesh size change in circuit,

Heating medium change for fuel oil heaters(i.e.use of 150# steam against 35~40# or vice versa etc.)

Best Regards
Qalander(Chem)

 

[jmw]

See comment on heater control in the "DP" thread.
Poor viscosity control may be a problem.

Some possibilities are:
The heat exchanger is fouled or partially obstructed so that heat transfer takes place through a smaller surface area but with higher temperatures casing some problems with the fuel.
The fuel is more viscous than the heat exchangers were originally designed for such that the target temperature is higher and the heating fluid flow rates and temperatures at the heat transfer areas are higher.

Possibly also the fuel is not behaving as a blend but a mixture with some separation in the heat exchanger?

Not sure about this one but most heavy fuel oils are today a blend of residual oils with low value low viscosity cutter stocks. If the resid and cutter are not compatible the fuel can stratify and it can separate in storage. What you would then see is that the fuel will start to flow with a high density and high viscosity requiring more heating and then progressively the viscosity and density will reduce... or maybe you will see step reductions in density and viscosity as you consume fuel from storage.
Heater control will depend on how you control the heaters... using temperature (excess oxygen and flame inspection) or online viscometers).

If temperature then there maybe rapid transitions that take the lab testing some time to detect. Much also depends on how and where samples are taken from to determine the EVT.

One bunker fuel supplier told me he did a top middle and bottom sample on his 380cst storage. Normally these samples are combined and tested for the aggregate value but he had them separately analysed. Top was 215cst and bottom was 450cst.

How it layered out, he had no way of knowing. This is fuel that is resident normally for very short periods of time before resupply.

I'd suggest a survey of how your fuel is received, a quality check as received, and a survey of how the uel is managed. As you go from the bottom of one tank to another you may find a significant increase in density and viscosity as you go from the light values of what is left in one tank to the heavy fraction at the bottom of the next tank. Do you completely exhaust a tank before loading a new batch of fuel into that tank?

Be aware also that because of MARPOL ANnex VI which imposes low sulphur limits on marine fuels that the demand is such that it is no longer possible to select a fuel that is naturally low sulphur (derived from low sulphur crudes)but is now achieved by cross blending low sulphur and high sulphur fuels which come from different refineries and different crudes. This is resulting in a lot of fuel quality issues with separation and compatibility being serious problems. These problems are most evident with Large diesel engines but the consequences could be felt on burner heavy fuel oils since it affects the global fuel supply.





JMW

http://www.ViscoAnalyser.com