FIELD OF THE INVENTION

The present disclosure relates to a fuel composition and a method for producing a fuel composition. BACKGROUND

The following background description art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the present disclosure. Some such contributions disclosed herein may be specifically pointed out below, whereas other such contributions encompassed by the present disclosure the invention will be apparent from their context.

A Fischer-Tropsch (FT) process may be used to convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process enables producing synthetic fuel from coal, natural gas, or biomass.

A gas to liquids (GTL) process is a refinery process that enables converting natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases may be converted into liquid synthetic fuels either via direct conversion or via syngas as an intermediate.

A freezing point of jet fuel is the lowest temperature at which the fuel remains free of solid hydrocarbon crystals that may restrict the flow of the fuel through filters, if present in the fuel system of the aircraft. The temperature of the fuel in the aircraft tank normally falls during flight depending on the aircraft speed, altitude, and flight duration. The freezing point of the fuel needs to be lower than the minimum (i.e. lowest) operational tank temperature.

EP 1664249 Bl discloses a fuel composition of petroleum derived kerosene fuel and FT-derived kerosene fuel, which composition has a lower freezing point than that of the fuel components.

SUMMARY

The following presents a simplified summary of features disclosed herein to provide a basic understanding of some exemplary aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to a more detailed description. According to an aspect, there is provided the subject matter of the independent claims. Embodiments are defined in the dependent claims.

An exemplary multipurpose fuel composition comprises petroleum derived jet fuel component and renewable jet fuel component, wherein the multipur- pose fuel composition has a freezing point of -40°C or below, and a cetane number more than 40, preferably more than 45, more preferably more than 50.

An exemplary method comprises producing a multipurpose fuel composition, the method comprising mixing petroleum derived jet fuel component and renewable jet fuel component to obtain a multipurpose fuel composition having a freezing point of -40°C or below, and a cetane number more than 40, preferably more than 45, more preferably more than 50.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

Figure 1 shows measured and calculated freezing points of exemplary fuel compositions comprising a renewable jet fuel component having a distillation range from 180°C to 315°C blended with a petroleum derived jet fuel component;

Figure 2 show measured and calculated freezing points of exemplary fuel compositions comprising a renewable jet fuel component having a distillation range from 145°C to 280°C blended with a petroleum derived jet fuel component. DETAILED DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising", "containing" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may contain also features/structures that have not been specifically mentioned. Jet aircraft is exposed to low operating temperatures, and it is necessary that the fuel used in the aircraft does not freeze in these conditions. Blocking of fuel filters and pumpability of the jet fuel are dependent on the freezing point of the fuel. The Jet A fuel specification has limited the freezing point of the Jet A fuel to a maximum of -40°C. The Jet A-1 fuel specification has limited the freezing point of the Jet A-1 fuel to a maximum of -47°C.

Because jet fuel is a mixture of hundreds of individual hydrocarbons each having its own specific freezing point, jet fuel does not become solid at one temperature. When the fuel is cooled the hydrocarbons with the highest freezing point solidify first. Further cooling causes the hydrocarbons with a lower freezing point to solidify.

The quality of diesel fuel may be determined by using the cetane number (CN). The cetane number is an inverse function of the fuel's ignition delay, and a time period between the start of injection and the first identifiable pressure in- crease during combustion of the fuel. In a particular diesel engine, higher cetane fuels have shorter ignition delay periods than lower cetane fuels.

Gas-to-liquids (GTL) jet fuel is typically not used in diesel engines in ground vehicles. The properties of the GTL jet fuel (i.e. GTL kerosene), such as the cetane number, flash point and the distillation range are not suitable for modern diesel engine use.

An embodiment discloses a multipurpose fuel composition comprising petroleum derived jet fuel component and renewable jet fuel component.

In an embodiment the renewable jet fuel component is hydrotreated renewable middle distillate.

Another embodiment discloses a multipurpose fuel composition comprising a petroleum derived jet fuel component and a renewable jet fuel component with a distillation range from 145°C to 315°C.

Another embodiment discloses a multipurpose fuel composition comprising a petroleum derived jet fuel component and a renewable jet fuel component with a distillation range from 145°C to 280°C.

Another embodiment discloses a multipurpose fuel composition comprising a petroleum derived jet fuel component and a renewable jet fuel component with a distillation range from 180°C to 315°C.

Thus an embodiment discloses a multipurpose fuel composition which is a blend of a petroleum derived jet fuel component and renewable jet fuel com- ponent, and which is usable as a fuel in both aircrafts and ground vehicles. The resulting blend has a better (i.e. lower) freezing point than the neat components. This enables utilization of fuel components with a poorer (i.e. higher) freezing point. The cetane number of the multipurpose fuel composition is high enough so the composition may be used in diesel engines.

Petroleum derived jet component typically comprises C7 to C15 hydrocarbons or C8 to C16 hydrocarbons, for example. The amount of such hydrocarbons may be more than about 95 wt-% of the component, or more than about 99 wt-% of the component. Petroleum derived jet fuel component typically comprises i-par- affins, n-paraffins, naphthenes, and/or aromatics. In the petroleum derived jet fuel component, the amount of i-paraffins is typically about 15 to about 35 wt-%, or about 20 to about 30 wt-%, such as about 25 wt-%. In the petroleum derived jet fuel component, the amount of n-paraffins is typically about 10 wt-% to about 30 wt- %, or about 15 wt-% to about 25 wt-%, such as about 20 wt-%. In the petroleum derived jet fuel component, the amount of naphthenes is typically about 15 wt-% to about 35 wt-%, or about 20 wt-% to about 30 wt-%, such as about 25 wt-%. In the petroleum derived jet fuel component, the amount of aromatics is typically about 20 wt-% to about 40 wt-%, or about 25 wt-% to about 35 wt-%, such as about 30 wt-%.

Renewable jet fuel component typically comprises i-paraffins and n- paraffins and only a minor amount of other compounds. In the renewable jet fuel component, the amount of i-paraffins is typically more than about 50 wt-%, more than about 60 wt-%, more than about 70 wt-%, more than about 80 wt-%, or more than about 90 wt-%. Typically the amount of C15 to C18 paraffins in the renewable jet fuel component is more than about 70 wt-%, more than about 85 wt-%, or more than about 90 wt-%. In the renewable jet fuel component, the amount of paraffins smaller than C15 paraffins is typically less than about 20 wt-%, less than about 10 wt- %, or less than about 7 wt-%. In the renewable jet fuel component, the amount of paraffins larger than C18 paraffins is typically less than about 10 wt-%, less than about 5 wt-%, or less than about 3 wt-%. The amounts of C15, C16, C17 and C18 hydrocarbons may vary in the renewable jet fuel component.

An embodiment discloses a fuel composition with a predefined freezing point (or freezing point range) and predefined cetane number (or cetane number range). An embodiment discloses a fuel composition with a predefined combination of freezing point (or freezing point range) and cetane number (or cetane number range).

An embodiment discloses a multipurpose fuel composition comprising petroleum derived jet fuel component and renewable jet fuel component, wherein the freezing point of the multipurpose fuel composition is -40°C or below, and the cetane number of the multipurpose fuel composition is more than 40, preferably more than 45, more preferably more than 50.

An embodiment discloses a method for producing a fuel composition, the method comprising mixing petroleum derived jet fuel component and renewable jet fuel component in an amount to obtain a multipurpose fuel composition having a freezing point -40°C or below and a cetane number of more than 40.

An embodiment discloses a multipurpose fuel composition comprising petroleum derived jet fuel component and renewable jet fuel component, wherein the freezing point of the multipurpose fuel composition is -47°C or below.

An embodiment discloses a method for producing a fuel composition, the method comprising mixing petroleum derived jet fuel component and renewable jet fuel component in an amount to obtain a multipurpose fuel composition having a cetane number of more than 50.

The cetane number of the blend may be obtained by linear calculations from the cetane numbers of the blended components.

An embodiment discloses a fuel which is a blend (i.e. mixture) of 1) a petroleum derived jet fuel component, and 2) a renewable jet fuel component. An exemplary fuel is usable as a multipurpose fuel, i.e. it is usable both as diesel fuel (e.g. in ground vehicles) and as jet fuel (e.g. in aircrafts), since the cetane number of the fuel composition is such that it allows the use of the fuel composition in ground vehicles (such as cars, trucks etc.) in addition to the use in aircrafts. This is logistically beneficial, for example, in remote areas or crisis situations when it may be laborious to provide diesel fuel and jet fuel separately.

An exemplary fuel composition has a lower freezing point than that of the components. Thus the freezing point of the fuel composition may be upgraded by utilizing renewable fuel components in jet fuel and multipurpose fuel manufacturing and blending. For example, when blending the petroleum derived jet fuel component and the renewable jet fuel component, the freezing point requirement of Jet A-l grade (maximum freezing point -47°C) may be fulfilled even though the fuel components were only of Jet A grade (maximum freezing point -40°C). A difference between the renewable jet fuel component and GTL kerosene is that the GTL kerosene (i.e. GTL jet fuel) has an iso-paraffin content from 20 wt- % to 50 wt-%, whereas the renewable jet fuel component has an iso-paraffin content of more than 70 wt-%, preferably more than 80 wt-%, more preferably more than 90 wt-%.

A further difference between the renewable jet fuel component and GTL kerosene is that the GTL kerosene (i.e. GTL jet fuel) has a freezing point of -42.5°C to -53.5°C and a flash point of 42°C to 48.5°C, whereas the renewable jet fuel component typically has a freezing point of -29°C to -33°C and typically a flash point above 61°C.

Table 1 discloses physical properties of the renewable jet fuel component in comparison with conventional GTL kerosene.

Table 1. Comparison between renewable jet fuel component and conventional GTL kerosene component

In order to achieve the advantageous freezing point lowering phenomena of the fuel composition, there are requirements for the conventional petroleum derived jet fuel component and renewable jet fuel component, since it is required that the difference between the freezing points of the components used is less than 25°C.

The renewable jet fuel component herein refers to a jet fuel component produced from vegetable oil and/or animal fats. Palm oil, rapeseed oil, and/or waste fat from the food industry may be used as a raw material for the production of the renewable jet fuel component. Other examples of possible raw materials in- elude waste fats from the food industry, biogas, algae oil, jatropha oil, soybean oil, and/or microbial oil. Examples of possible waste fats from the food industry include cooking oil, animal fat, and/or fish fat. Renewable fuel refers to biofuel produced from biological resources formed through contemporary biological processes. Herein the renewable jet fuel component is produced from vegetable oil and/or animal fat.

In an embodiment, the renewable jet fuel component is produced by means of a hydrotreatment process. Hydrotreatment involves various reactions where molecular hydrogen reacts with other components, or the components undergo molecular conversions in the presence of molecular hydrogen and a solid catalyst. The reactions include, but are not limited to, hydrogenation, hydrodeoxy- genation, hydrodesulfurization, hydrodenitrification, hydrodemetallization, hy- drocracking, and isomerization. The renewable jet fuel component may have different distillation ranges which provide the desired properties to the component, depending on the intended use.

In an embodiment, the freezing point of the multipurpose fuel composition is -55°C or below, preferably -55.2°C or below, more preferably -55.6°C or below, yet more preferably -55.9°C or below, yet more preferably -57.4°C or below, yet more preferably -58.2°C or below.

In an embodiment, the multipurpose fuel composition comprises at least 1 vol-% of renewable jet fuel component, preferably at least 5 vol-%, more preferably at least 10 vol-%, yet more preferably at least 15 vol-%, yet more pref- erably at least 15 vol-%, yet more preferably at least 50 vol-%.

In an embodiment, the petroleum derived jet fuel component has a freezing point between -47°C and -60°C, wherein the difference between the freezing point of the renewable jet fuel component and the freezing point of the petroleum derived jet fuel component is less than 25°C. EXAMPLE 1

The freezing points of multipurpose fuel compositions were measured using a test method IP 529. The measured freezing points of the fuel compositions were compared to freezing points calculated by linear calculations (i.e. based on the volume percentages of the components in the fuel composition).

It was noticed that fuel compositions comprising renewable jet fuel component with a distillation range from 180°C to 315°C, blended with a petroleum derived jet fuel component had a better (i.e. lower) freezing point than predicted according to linear calculations (see Table 2 and Figure 1). This effect was seen when the amount of the renewable jet fuel component in the blends was 20 vol-% or less. When renewable jet fuel component having a distillation range from 145°C to 280°C was blended with a petroleum derived jet fuel component (see Table 3, Figure 2, Table 4), the lowering of the freezing point was even bigger, and the effect was seen with up to over 50 vol-% of renewable jet fuel component in the blend.

The freezing point lowering phenomena of the blend was detected when the petroleum derived jet fuel had a freezing point between -47°C and -60°C, and when the difference between the renewable fuel freezing point and petroleum derived jet fuel freezing point was less than 25°C.

Table 2. Measured and calculated freezing points of fuel compositions comprising renewable jet fuel component with distillation range 180°C - 315°C blended with petroleum derived jet fuel component

Renewable jet Measured freezing Calculated freezing Difference (°C) fuel content point (°C) point, linear (°C)

(vol-%)

0 -54.7 -54.7 0.0

1 -54.9 -54.5 0.4

5 -55.3 -53.5 1.8

10 -55.7 -52.4 3.3

15 -54.1 -51.2 2.9

30 -46.0 -47.7 -1.7

50 -41.3 -43.1 -1.8

100 -31.5 -31.5 0.0

Table 3. Measured and calculated freezing points of fuel compositions comprising renewable jet fuel component with distillation range 145°C - 280°C blended with petroleum derived jet fuel component

Table 4. Measured and calculated freezing points of fuel compositions comprising renewable jet fuel component with distillation range 145°C - 280°C blended with petroleum derived jet fuel component

Figure 1 shows measured and calculated freezing points for a fuel com- position comprising renewable jet fuel component with a distillation range from 180°C to 315°C blended with petroleum derived jet fuel component.

Figure 2 shows measured and calculated freezing points for a fuel composition comprising renewable jet fuel component with a distillation range from 145°C to 280°C blended with petroleum derived jet fuel component.

Cetane numbers of the multipurpose fuel compositions containing renewable jet fuel component and petroleum derived jet fuel component were measured using the EN15195 method. The results obtained are presented in Table 5. Table 5 shows the content of renewable jet fuel component (RJF) in the fuel composition, as well as the cetane number of the fuel composition. The results show that cetane numbers behave linearly. Therefore, the cetane number of the multipurpose fuel composition may be calculated from the cetane numbers of the re- newable jet fuel component and petroleum derived jet fuel component, as presented in Table 6.

Table 5. Cetane numbers of blends containing petroleum derived jet fuel component and renewable jet fuel component having a distillation range from l80°C to 315°C

The example 1 shows the superior freezing point behavior of the renew- able jet fuel based blending component. This behavior was seen with up to 20 vol- % renewable jet fuel component in the blend with conventional petroleum derived jet fuel. Similar kind of superior freezing point behaviour was also shown with the renewable jet fuel component with a slightly lower distillation range. The superior freezing point behaviour was seen with up to over 50 vol-% renewable jet fuel com- ponent in the blend with conventional petroleum derived jet fuel component.

The freezing points and cetane numbers of the multipurpose compositions are such that they may be used in aircrafts as well as in ground vehicles.

EXAMPLE 2 (COMPARATIVE EXAMPLE)

The freezing points of fuel compositions were measured using a test method IP 529. The measured freezing points of the fuel compositions were compared to freezing points calculated by linear calculations (i.e. based on the volume percentages of the components in the fuel composition). It was noticed that fuel compositions comprising renewable jet fuel component with a freezing point of -31.5°C, blended with a petroleum derived jet fuel component with a freezing point of -73.3°C, did not have a better freezing point than predicted according to linear calculations (see Table 7).

Table 7. Measured and calculated freezing points of renewable jet fuel component and petroleum derived jet fuel component blends

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.