Is heating oil filtered to produce higher grades?

[marcophys]

Fuel for a paraffin/kerosene inverter heater is sold typically in 20L containers (in Europe).
They all claim to be highly filtered to remove odour, and burn cleaner.

Customers are also given the opportunity to pay more for different brands, but they all seem to meet the same standards.​

The heater instructions indicate that this high-grade paraffin should be used, and not heating oil.
Further, I note that user reports do indicate carbon build up on the flame rod and gasifier, when heating oil is used.
Whereas, my heater has only used high-grade paraffin, and there is zero carbon build up.

I'm wondering... what is the science behind this?
Is filtration just a marketing term, when really the high-grade paraffin is simply refined differently.

... and is it then burning at a higher temperature (than standard heating oil), thereby ensuring that less carbon is deposited.

Is this fuel the Naphtha, that is shown on the classic refining charts?

 

[marcophys]

Just had time to do a little more research on this.
The story of the 10 names is listed first, with refs.
You can jump this section and go straight to the detailed specs
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10 names & Refs
As is often the case we end up at Wikipedia where also as is often the case... subsequent paragraphs, and linked pages, tend rather to cloud rather than illuminate understanding.

The multiple names certainly don't help, as AKA followed by a different spec doesn't help.
The first article is here https://en.wikipedia.org/wiki/Kerosene

"Kerosene, also known as paraffin, lamp oil and coal oil... widely used as a fuel in industry and households...Liquid paraffin (called mineral oil in the US) is a more viscous and highly refined product which is used as a laxative."... (considering paraffin is liquid... 'liquid paraffin doesn't help') :)​

But wait, we also have https://en.wikipedia.org/wiki/Fuel_oil
Number 1 fuel oil is a volatile distillate oil intended for vaporizing pot-type burners.[3] It is the kerosene refinery cut that boils off right after the heavy naphtha cut used for gasoline. Older names include coal oil, stove oil and range oil.[2]

But wait again!
Further down the page, we learn that it is AKA No. 1 distillate No. 1 diesel fuel Distillate 9-16 (chain length)

So, I do more searching and of course find another name: 28 Second Kerosene Heating Oil

So we have at least 10 names.
Of these 10 names, it is not readily apparent what are the differing grades.
There are even more names that this, but I'm leaving out No.2 to No 6 Fuel oils, as being presumably heavier.

On top of this, we have commercial sales ops, offering three different grades of paraffin purity, which I won't list as they offer no spec sheets.
--------------------------

Okay... let's resolve the data
British Fuel Oils (bulk delivery) kindly provide three spec pdf's:

1. https://www.britishfueloils.co.uk/bfo-gas-oil-a2-specification.pdf
2. https://www.britishfueloils.co.uk/bfo-bs-2869-kerosene-class-c2-spec.pdf
3. https://www.britishfueloils.co.uk/bfo-bs2869-class-c-premium-paraffin-spec.pdf

1. Is for tractors (so not massively relevant, but worth including)
2. 28 second Kerosene vs 3. Premium Paraffin
Lower flash point, lower smoke point, lower energy, yet higher char value and higher sulphur content.

Notice also how the twats don't list comparative test results.
Notice how they attempt to bamboozle us, by using J/g and MJ/Kg
(I've seen this type of obfuscation in many oil spec docs)

The final hidden grade, is what I bought for my heater
In fact, having researched all the codes on the container, they provide no information other than standard safety specs.
The two data elements that might be useful are:
0.01 g/g odours (it's French and it's meaning is not clear - maybe it is sulphur but the Brit specs list no odour data)
Min Flash-point: 61 degC

The Actual standards
It then dawned on me that we needed the defined British Standards, from which the fuel companies must work.
These standards must provide us with a primary guide as to what we are looking for (in developed states) regarding: C1 & C2 basic specs.
The assumption being that if fuels are within these specs, we can then understand what we are buying, and burning, within our homes.

I found them here: https://www.gov.uk/government/uploa...achment_data/file/296420/geho0211btmo-e-e.pdf
Pages 15 & 16
Bingo!
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Analysis

We are interested in:

1. Safety
2. Energy when burned
3. Clean burn
4. Smell

I'm going to look at this further.

 

[russ_watters]

Can't help you, but kudos for doing your own quality research!

 

[marcophys]

Safety
I have found the UK Gov Toxicological Report:
https://www.gov.uk/government/uploa...29/hpa_kerosene_toxicological_overview_v2.pdf

The important overview states that "flue-less appliances use “paraffin” (C1) fuel"

The report is worth a read from a chemistry perspective as the annex provides the general chemical composition of C2 fuel (C1 is not provided).

BS-2869 Specs C1 & C2

We can see:
C2 maximum metal content is much higher for zinc, copper, and lead.
C2 Halogens as Chlorine 30 times higher
C2 Sulfur content could be ten times higher - creating odour
C2 Ash is 20 times higher - burn cleanliness

Energy (ref British Fuel Oil specs above)
Gross calorific value
C1 J/g 46.5
C2 J/g 42.8 less energy produced

Summary & Conclusion
When it is cold we must try to keep warm... but fuel is damn expensive.
C1 Paraffin can be sold at twice the price of kerosene (so do your research).
Both fuels will burn in a home heater, and because of this many people suggest that kerosene can be used, at risk of clogging the fuel rod and combustion chamber, or wick.
The principal being that the lower cost, justifies the occasional strip and clean up, and putting up with the smell.
However, the above research proves that in doing so, the occupants of the house will be breathing far more dangerous toxic fumes.
The UK Gov Toxicology Report clearly indicates C1 paraffin should be used in flueless heaters.

If C1 grade fuel is not available in your country, and you must have heat to survive - this information clearly drives home the need for careful positioning of the heater and very good ventilation.
The blown heaters (injector gasifier type) will be the worst heater option, as all result of combustion is blown into the room.
The high temp radiant heaters (wick type) vent the fumes upwards - therefore it could be placed beneath a chimney, or a flue should be arranged, to lead the fumes outside.

Special Note on Aviation grade fuel
This will also burn in these heaters, and I have seen people suggesting this fuel as an alternative.
This is not at all recommended as it is saturated with many different chemicals, in addition to those poisons mentioned above.

Stay warm & stay safe & check the specs, not the name.
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[Asymptotic]

To me, "filtering" suggests a physical filtration medium that captures particles above a certain size. On the other hand, it wouldn't be inaccurate in the broader sense when used to signify a greater degree of purification. As you've noted, the term "kerosene" began as a brand name for a specific formulation of coal oil, and it's meaning over the years has evolved to indicate a particular range of petroleum distillates.

In the U.S., ASTM DS3699-90 tests are identical between 1-K and 2-K kerosene except for sulfur content. 1-K is low sulfur (0.04% or less by weight) suitable for a flue-less heater. 2-K sulfur content is between 0.04% and 0.3%, and only suitable for flue-equipped heaters.

A review of various supplier SDS sheets show a considerable constituent range for what can be called kerosene. For instance (although they don't call it 1-K kerosene), W.M. Barr sells a formulation called "Klean Strip Kerosene" which is actually a mixture of Stoddard's solvent and trimethylbenzene, and not something I'd want to burn, particularly in an unvented space. They have another formulation intended for kerosene lamps and heaters called "Klean Heat Kerosene Substitute" which actually is a form of low-sulfur kerosene - CAS #64742-47-8, "Hydrotreated light distillate (petroleum)".

Mostly, I've seen CAS #8008-20-6 "Kerosine (petroleum)" with, depending on the manufacturer (Marathon Oil, Shell, etc.) anything from 0.04% up to 5% of naphthalene (CAS# 91-20-3).

I'm using 1-K kerosene from a local mini-mart that sells Valero branded fuels. Valero Energy's SDS lists their kerosene as 100% CAS# 64742-81-0, "Kerosine (petroleum), sweetened", and signage at the pump says sulfur content is 15 ppm (about 0.0015%). Interestingly, one of the synonyms for CAS #64742-81-0 is "Jet A-1" suggesting this formulation is used as the base for A-1 aviation grade kerosene although, as you've noted above, jet fuel itself isn't suitable as an unvented burner fuel due to various additives.

From what I've been able to discern, #8008-20-6 is straight cut from primary fractional distillation, while #64742-47-8, and #64742-81-0 have both been treated with additional processing steps to reduce the content of sulfur, and other noxious compounds. What we call 1-K kerosene appears to be nearly identical to BS2869-C1.