1 reply to this topic

[Adriaan]

I was wondering about the result of blending oils. I basically have NO experience with the subject and was wondering about the following particular properties;

1. BMCI index
2. LHV (lower heating value) - for the purpose of flame temperature calculation
3. density

For mixtures of oils - between 25 and 50 % of one type of oil, the rest of another type, for each of which the above properties are known - would it be okay to to simply take the proportional average of the properties (the results aren't critical, thankfully!) or do I need to do something else?

Where I work we do not blend oils (well we DO, really, but only in the big tank when a new shipment is added). I produced a (software) system that I am now trying to adapt for use in a sister company where AT REACTOR oil blending is used. I am mainly interested in the LHV (because the combustion temperature is a critical element in the system / production and it is relatively easy to calculate said temperature IF the LHV is known / can be calculated). They (sister company boss) use the BMCI - dunno what FOR - and density so I sort of have to add them to my system.

All oil types used are HEAVY fractions, aromatic oils (Kreosote, Coaltar destillate etcetera). I THINK they are pre-heated before the inline blending, so the blend ought to be fairly homogenous.

[JMW]

I was wondering about the result of blending oils. I basically have NO experience with the subject and was wondering about the following particular properties;

1. BMCI index
2. LHV (lower heating value) - for the purpose of flame temperature calculation
3. density

For mixtures of oils - between 25 and 50 % of one type of oil, the rest of another type, for each of which the above properties are known - would it be okay to to simply take the proportional average of the properties (the results aren't critical, thankfully!) or do I need to do something else?

Where I work we do not blend oils (well we DO, really, but only in the big tank when a new shipment is added). I produced a (software) system that I am now trying to adapt for use in a sister company where AT REACTOR oil blending is used. I am mainly interested in the LHV (because the combustion temperature is a critical element in the system / production and it is relatively easy to calculate said temperature IF the LHV is known / can be calculated). They (sister company boss) use the BMCI - dunno what FOR - and density so I sort of have to add them to my system.

All oil types used are HEAVY fractions, aromatic oils (Kreosote, Coaltar destillate etcetera). I THINK they are pre-heated before the inline blending, so the blend ought to be fairly homogenous.

I'll be interested to see some of the replies.
Oil blending is usually based on the fuel target viscosity and most of the available calculators appear to be modelled on ASTM D341.
Many of the blend properties are additive but some, like viscosity, are not.
In burner and engine applications, the heating of the fuel is usually controlled to optimise the fuel viscosity for the best atomisation and most of the fuel oil blend calculators also show the injection temperature for a given target injection viscosity though the heater is controlled using an in-line viscometer. In-line viscometers are increasingly used for fuel oil blending control since they can help achieve a precise blend without the extra cutter stock needed for a "hot blend" (one guaranteed to be below the maximum allowed viscosity.... if the fuel is to viscous the fuel oil heaters may have insufficient capacity to raise the fuel temperature enough).
"Hot Blends" cost more money because the distillate is the expensive part.
Once you are measuring density and viscosity in-line it is a short step to calculate many of the required parameters live (as the fuel flows) such as Ignition index, base density and base viscosity. I believe the Viscosity Gravity gradient is also calculated from density and viscosity and is a measure of the kerosene or parafin composition.