WAX FLOW VISCOSITY FOR FUELS

Description

FIELD

[0001] This application relates to marine fuel compositions.BACKGROUND

[0002] Marine fuel compositions, sometimes referred to as bunker fuel, have conventionally included heavy gas oils that may be otherwise difficult and / or expensive to convert to a beneficial use. The heavy gas oils may include heavier distillation fractions that are lightly processed (or even unprocessed), such as vacuum gas oils, heavy atmospheric gas oil, and residual components. Due in part to use of the marine fuel compositions in international waters, the fuels have typically incorporated heavy gas oils with relatively high sulfur content. However, many countries have recently adopted local specifications for lower sulfur emissions from marine vessels. In addition, the International Maritime Organization is implementing a new global sulfur limit of 0.50 wt.% sulfur, effective January 1, 2020, commonly referred to as "IMO 2020."

[0003] In preparing low-sulfur fuels that are IMO 2020 compliant, different hydrocarbon components can be blended. These different hydrocarbon components can include wax, such as paraffin wax, as a byproduct of the refining process. Since wax can be problematic, there is a need to manage wax content when making IMO 2020 compliant marine fuel compositions. For example, solid wax in the marine fuel compositions can lead to filter blocking in the fuel handling system and starve the engine of fuel. If solid wax is present, the marine fuel compositions may be heated to melt any wax prior to injection into the engine. However, engine manufacturers also specify a viscosity at which the marine fuel composition should be injected into the engine. Raising the temperature of the fuel to melt the wax may result in too low of a viscosity.

[0004] US Patent publication 9,057,035 B1 describes low-sulfur marine fuel compositions comprising 10-50 wt% of a residual hydrocarbon component. US Patent application publication 2012 / 246999 A1 describes low-sulfur marine fuel compositions with a reduced concentration of components that have been cracked.SUMMARY

[0005] Provided herein is marine fuel composition according to claim 1.

[0006] Further provided herein is a method of blending marine fuel compositions according to claim 2.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] These drawings illustrate certain aspects of the present invention and should not be used to limit or define the invention. FIG. 1 illustrates a prophetic graph of temperature versus heat flow for a marine fuel composition. FIG. 2 illustrates a graph of temperature versus heat flow for two different marine fuel compositions. DESCRIPTION

[0008] Provided herein are marine fuel compositions that are low sulfur. Embodiments disclosed herein may use wax flow viscosity to provide marine fuel compositions with essentially no solid wax in the marine fuel composition as it is being injected into the engine that also meet viscosity requirements of the engine manufacturer. As used herein, the term "wax flow viscosity" refers to the minimum kinematic viscosity at about 50 °C necessary to ensure that essentially all the wax in the marine fuel composition is melted prior to fuel injection at a minimum operational viscosity as specified by an engine manufacturer. Essentially all the wax is considered to be melted where about 98 wt.% or more of the wax in the marine fuel composition is melted.

[0009] As described above, many countries have adopted local specifications for lower sulfur emissions from marine vessels. Even further, IMO 2020 is requiring development of new marine fuel compositions that are low sulfur to meet the new sulfur requirements that are being implemented on January 1, 2020. In addition to IMO 2020, marine fuel compositions classified as residual marine fuels must meet the requirements of ISO 8217, Fuel Standard Sixth Edition 2017, Table 2, while marine fuel compositions classified as distillate marine fuels must meet the requirements of ISO 8217, Fuel Standard Sixth Edition 2017, Table 1.

[0010] To provide marine fuel compositions that are low sulfur, the method provided herein includes blending heavy gas oils, which are conventional hydrocarbon components that are typically higher in sulfur content, with lighter gas oils that are typically lower in sulfur content. While this can provide marine fuel compositions with desirable sulfur concentrations, embodiments may further include monitoring the viscosity and wax content of the marine fuel compositions to ensure adequate flowability without undesirable wax levels. For example, the heavy gas oils typically have a high viscosity while the lighter gas oils typically have a low viscosity. The use of the lighter gas oils that are low sulfur in embodiments of the marine fuel compositions can reduce the viscosity of the marine fuel composition to levels that may be lower than conventional marine fuel compositions.

[0011] Suitable marine fuel compositions include a hydrocarbon component or blend of two or more hydrocarbon components such that the marine fuel compositions have the properties enumerated herein: sulfur content, density, kinematic viscosity at 50 °C ("KV50"), and wax endpoint temperature. A marine fuel composition prepared by the method provided herein includes a heavy gas oil and / or a lighter gas oil. The heavy gas oil typically may include long-chain paraffinic molecules that can form a solid wax at moderate temperatures, such as ambient to about 130 °C. In addition, to problems with wax formation, the heavy gas oils are also typically lightly (or even unprocessed) so can contain higher sulfur content. To provide the requisite sulfur levels and acceptable wax flow viscosities, the heavy gas oil is blended with the lighter gas oil. The composition of the components of the marine fuel compositions and their relative proportions can be selected to provide a marine fuel composition having the properties enumerated herein.

[0012] Heavy gas oil is defined as a hydrocarbon fraction in which at least 50 vol.% boils at 500 °C to 750 °C (as measured by ASTM D86-18) at atmospheric pressure, for example, about 550 °C to about 650 °C or about 575 °C to about 625 °C. Boiling ranges in weight percent may also be determined using the measurement technique described in ASTM D2887-18, ASTM D6352-15, or ASTM D7169-18. Additional properties that can characterize heavy gas oils, include, but are not limited to, density and KV50. In some embodiments, the heavy gas oil may have a density in g / cm 3< of about 0.93 to about 1.0, for example about 0.95 to about 1, or about 0.93 to about 0.95. In some embodiments, the heavy gas oil may have a KV50 in centistokes ("cSt") of about 30 or greater, for example about 30 to about 2,500,000, about 30 to about 100, about 100 to about 10,000, or about 500 to about 1,000. In some embodiments, the heavy gas oil may have a high sulfur content. For example, the heavy gas oil may have a sulfur content in wt.% of greater than about 0.10, for example about 0.10 to about 5, about 0.50 to about 3, or about 1 to about 2.5. Examples of suitable heavy gas oils may include a variety of different hydrocarbon fractions including, but not limited to, distillates and residues, such as heavy atmospheric gas oil, vacuum gas oil, vacuum residuals from fractionating (total / partial) crude oils, atmospheric residuals from fractionating (total / partial) crude oils, visbreaker residuals, deasphalted residuals, and slurry oil, among others. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate heavy gas oil for a particular application.

[0013] Lighter gas oils are referred to herein as "lighter" because they have a reduced boiling point than the previously described heavy gas oil. The lighter gas oils are defined as a hydrocarbon fraction in which at least 50 vol.% boils at 200 °C to 550 °C (as measured by ASTM D 86-18) at atmospheric pressure, for example, 200 °C to about 400 °C or 200 °C to about 350 °C. Boiling ranges in weight percent may also be determined using the measurement technique described in ASTM D2887-18. Additional properties that can characterize lighter gas oils, include, but are not limited to, density and KV50. In some embodiments, the lighter gas oil may have a density in g / cm 3< of about 0.8 to about 1.0, for example about 0.8 to about 0.9, about 0.83 to about 0.87, or about 0.9 to about 1. In some embodiments, the lighter gas oil may have a KV50 in cSt of about 1 to about 30, for example about 1 to about 20, about 1 to about 10, about 1 to about 5, about 10 to about 20, or about 15 to about 20. In some embodiments, the lighter gas oil may have a low sulfur content, such that when blended with the heavy gas oil, the marine fuel composition may be considered IMO 2020 compliant. For example, the lighter gas oil may have a sulfur content in wt.% of less than about 0.05, for example, about 0.05 to about 0.0001, about 0.1 to about 0.0001, or about 0.001 to about 0.0005. Examples of suitable lighter gas oils may include a variety of different hydrocarbon fractions including, but not limited to, light atmospheric gas oil from the atmospheric tower in fractionating (total / partial) crude oil, automotive fuel oil, or hydrocarbon fractions from the catalytic cracker main fractionator. A specific example of a lighter gas oil may include diesel, such as ultra-low-sulfur diesel, which is defined by the Environmental Protection agency to have a maximum sulfur content of 15 parts per million.

[0014] The heavier gas oils and / or the lighter gas oils may be included in the marine fuel compositions in any suitable concentration, to provide the marine fuel composition with desirable properties. For example, the heavier gas oil may be included in an amount of 1 vol.% to 90 vol.%, for example, about 1 vol.% to about 60 vol.%, about 1 vol.% to about 30 vol.%, about 1 vol.% to about to 10 vol.%, about 1 vol.% to about 5 vol.%, about 1 vol.% to about 3 vol.%, about 3 vol.% to about 90 vol.%, about 5 vol.% to about 90 vol.%, about 10 vol.% to about 90 vol.%, about 30 vol.% to about 90 vol.%, about 60 vol.% to about 90 vol.%, or about 80 vol.% to about 80 vol.%. By way of further example, the lighter gas oil may be included in an amount of 10 vol.% to 99 vol.%, for example, about 10 vol.% to about 90 vol.%, about 10 vol.% to about 60 vol.%, about 10 vol.% to about 30 vol.%, about 20 vol.% to about 99 vol.%, about 30 vol.% to about 99 vol.%, about 60 vol.% to about 99 vol.%, or about 90 vol.% to about 99 vol.%. One of ordinary skill in the art with the benefit of this disclosure should be able to select an appropriate amount of the heavier gas oils and / or the lighter gas oils to include in the marine fuel compositions for a particular application.

[0015] In some embodiments, viscosity of the marine fuel compositions may be monitored to ensure compliance with viscosity requirements from the engine manufacturers. Typically, engine manufacturers will specify a viscosity range at which a marine fuel composition should be injected into the marine engine. This viscosity requirement for injection may range, for example, from about 2 cSt to about 20 cSt, regardless of temperature. For example, the engine manufacturer may specify that the marine fuel should be injected at a kinematic viscosity ranging from about 12 cSt to about 18 cSt at ambient temperature in the engine room (e.g., 35° C to 40° C). This example range corresponds to a minimum kinematic viscosity at 50° C of 8 cSt for residual marine fuel. To meet the desired viscosity range, the temperature of the marine fuel composition may be modulated. For example, high viscosity marine fuel compositions may be heated to reduce the viscosity to meet the viscosity range, while low viscosity marine fuel compositions may be cooled to increase the viscosity.

[0016] In some embodiments, the wax content of the marine fuel compositions may be monitored to ensure that there is essentially no solid wax present when injected into the engine. As previously described, solid wax in the marine fuel composition can lead to filter blocking in the fuel handling system, thus potentially starving the engine of fuel. If solid wax is present in the marine fuel composition, embodiments may include increasing the temperature at which the marine fuel composition may be injected into the engine so that essentially all the wax would be melted and in the liquid phase prior to injection. However, with hydrocarbon components in the marine fuel composition that are low sulfur and low viscosity to reach the new sulfur requirements, the overall viscosity of the marine fuel composition may be lower such that raising the temperature to reduce solid wax may result in too low of viscosity. Accordingly, embodiments may include using wax flow viscosity to provide a marine fuel composition with an acceptable viscosity that also has acceptable wax levels. For example, a ratio of kinematic viscosity to wax flow viscosity may be specified that provides acceptable viscosity and wax levels in the marine fuel compositions.

[0017] Based on the relationship between viscosity and wax content for embodiments of the marine fuel compositions having low sulfur content, various desirable properties for a fuel oil composition may be specified. The marine fuel compositions provided herein have the following properties: (i) a sulfur content of 0.40 to 0.49 wt.% or less; (ii) a density at 15° C of 0.86 g / cm 3< to 0.95 g / cm 3< ; and (iii) a kinematic viscosity at 50° C ("KV50") of 10 cSt to 80 cSt.

[0018] One property used for selection and / or modification of embodiments of the marine fuel compositions is sulfur content. The marine fuel compositions may be considered IMO 2020-compliant in that the marine fuel oil compositions have a sulfur content of 0.50 wt.% or less. The marine fuel compositions have a sulfur content of 0.4 wt.% to about 0.49 wt.%. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate sulfur content for embodiments of the marine fuel compositions, as desired for a particular application.

[0019] Another property used for selection and / or modification of embodiments of the marine fuel compositions is density. The standardized test method in ISO 3675 (June 15, 1998) is defined as providing the procedure for determination of density. The marine fuel composition has a density at 15° C of 0.86 g / cm 3< to 0.95 g / cm 3< . For example, the density at 15° C of the marine fuel composition may be 0.86 g / cm 3< to about 0.93 g / cm 3< , 0.86 g / cm 3< to 0.9 g / cm 3< , 0.86 g / cm 3< to 0.89 g / cm 3< , or about 0.9 g / cm 3< to about 0.95 g / cm 3< . One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate density for embodiments of the marine fuel compositions, as desired for a particular application.

[0020] Yet another property that used for selection and / or modification of embodiments of the marine fuel compositions is KV50. The standardized test method in ISO 3104 (1997) is defined as providing the procedure for determining KV50. The marine fuel composition has a KV50 of 10 cSt to 80 cSt. In accordance with some embodiments, selection and / or modification of an appropriate KV50 in combination with wax flow viscosity provides an ability for the marine fuel compositions to meet viscosity requirements from engine manufacturers while also being essentially free of solid wax during injection into the engine. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate KV50 for embodiments of the marine fuel compositions, as desired for a particular application.

[0021] Yet another property that can be used for selection and / or modification of embodiments of the marine fuel compositions is ratio of KV50 to wax flow viscosity. It has been determined that there is relationship between wax flow viscosity and KV50. In accordance with certain embodiments, marine fuel compositions with an acceptable wax flow viscosity have a KV50 that is greater than the wax flow viscosity. By way of example, if the KV50 of the marine fuel composition is greater than the wax flow viscosity, then essentially all the wax should be melted at injection temperature. In other words, essentially all the wax in the marine fuel composition should be in a liquid state as it is being injected into the engine, thus reducing problems causes by solid wax blocking the fuel filters. In some embodiments, a marine fuel composition may have a ratio of KV50 to wax flow viscosity greater than 1. By way of example, the marine fuel composition may have a ratio of KV50 to wax flow viscosity of about 1.01 to about 25, for example, about 1.5 to about 25, about 2 to about 25, about 5 to about 25, about 10 to about 25, about 15 to about 25, about 20 to about 25, about 1.01 to about 25, about 1.01 to about 20, about 1.01 to about 15, about 1.01 to about 10, about 1.01 to about 5, about 2 to about 25, about 2 to about 20, about 2 to about 15, about 2 to about 10, about 2 to about 5, about 5 to about 20, about 5 to about 15, about 5 to about 10, about 10 to about 20, or about 10 to about 15. Specific examples of suitable marine fuel compositions may have a ratio of KV50 to wax flow viscosity of about 1.01, about 1.5, about 2, about 2.5, about 3, about 4, about 5, about 10, about 15, about 20, or about 25. In accordance with some embodiments, selection and / or modification of the ratio of KV50 to wax flow viscosity can provide an ability for the marine fuel compositions to meet viscosity requirements from engine manufacturers while also being essentially free of solid wax during injection into the engine. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select a ratio of KV50 to wax flow viscosity for embodiments of the marine fuel compositions, as desired for a particular application.

[0022] As previously described, the wax flow viscosity of a marine fuel composition is the minimum kinematic viscosity at about 50 °C necessary to ensure that essentially all the wax is melted prior to fuel injection at a minimum operational viscosity as specified by an engine manufacturer. Engine manufacturers may specify different viscosity ranges at which a marine fuel composition should be injected into the marine engine. This viscosity requirement for injection may range, for example, from about 2 cSt to about 20 cSt, regardless of temperature. For example, the engine manufacturer may specify that the marine fuel viscosity should be injected at a kinematic viscosity ranging from about 12 cSt to about 18 cSt at ambient temperature in the engine room (e.g., 35° C to 40° C), thus providing a minimum kinematic viscosity at the ambient temperature of 12 cSt, which corresponds to KV50 of 8 cSt.

[0023] A technique for determining wax flow viscosity will now be described. The method described herein is defined as providing the procedure for determining wax flow viscosity. The method includes determining a wax endpoint temperature for a marine fuel composition, identifying a minimum operational viscosity for use of the marine fuel composition, which may be required by the engine manufacturer, converting the minimum operational viscosity at the wax endpoint temperature to an estimated KV50, which is the wax flow viscosity; and rejecting the marine fuel composition if the ratio of the measured KV50 of the marine fuel composition to wax flow viscosity is less than 1. Should this ratio be the measured KV50 of the marine fuel composition or be greater than 1, then the marine fuel composition may have an acceptable wax flow viscosity, indicating that essentially all the wax will be melted during injection into the engine while having an acceptable kinematic viscosity.

[0024] In determining the wax flow viscosity, the method includes determining a wax endpoint temperature. As used herein, the term "wax endpoint temperature" refers to the temperature at which essentially all (98 wt.% or more) of the wax is melted at atmospheric pressure. Determining the wax endpoint can include measuring the temperature profile of the marine fuel composition. By way of example, the temperature profile may be measured using differential scanning calorimetry ("DSC") in which the difference in the amount of heat required to increase the temperature of a sample is measured as a function of temperature. The DSC may be performed, for example, in accordance with any suitable technique, including, but not limited to, ASTM D4419 - 90 (2015). In some embodiments, the wax endpoint point may be determined based on the DSC. Embodiments may use a heat flow or a heat flux DSC. The heat flow or heat flux determined from the DSC may be provided as function of temperature. FIG. 1 is an illustrative plot of heat flow as a function of temperature for a heat flow DSC. The plot is a prophetical example of an illustrative plot determining the wax endpoint temperature. On FIG. 1, the heat flow is plotted as a function of temperature, shown as curve 100. The point where curve 100 reaches an asymptote and returns to the baseline is the wax endpoint temperature. On FIG. 1, the wax endpoint temperature is about 70.43° C. The area under the line bounded by the curve 100 represents the wax content.

[0025] In determining wax flow viscosity, the method includes identifying a minimum operational viscosity required by the engine manufacturer. As previously described, engine manufacturers may specify different viscosity ranges at which a marine fuel composition should be injected into the marine engine. This viscosity requirement for injection may range, for example, from about 2 cSt to about 20 cSt, regardless of temperature For example, the engine manufacturer may specify that the marine fuel viscosity should be injected at a kinematic viscosity of about 12 cSt to about 18 cSt at ambient temperature in the engine room (e.g., 35° C to 40° C), thus providing a minimum kinematic viscosity at the ambient temperature of 12 cSt, which corresponds to KV50 of 8 cSt.

[0026] In determining wax flow viscosity, the method includes estimating the wax flow viscosity based on the wax endpoint temperature and the minimum operational viscosity. In some embodiments, the minimum operational viscosity at the wax endpoint temperature may be converted to an estimated KV50, which is the wax flow viscosity. Any suitable technique may be used for this conversion of the minimum operational viscosity at the wax endpoint temperature to the estimated KV50 (wax flow viscosity). For example, there are known relationships between viscosity and temperature for most grades of fuel, such as distillate and residual marine fuels, that can be used for this conversion. The marine fuel composition should have a measured KV50. Should the measured KV50 of the marine fuel composition be greater than the estimated or wax flow viscosity (i.e., a ratio of measured KV50 to wax flow viscosity of greater than 1), then the marine fuel composition may have an acceptable wax flow viscosity, indicating that essentially all the wax will be melted during injection into the engine while having an acceptable kinematic viscosity. However, should this ratio of measured KV50 to wax flow viscosity be less than 1, the marine fuel composition may be rejected. Remedial steps may be taken to adjust the wax flow viscosity to provide an acceptable wax flow viscosity. For example, the concentration of one or more components in the marine fuel composition may be adjusted. Alternatively, one or more additional hydrocarbon components may be added to the marine fuel composition.

[0027] The wax endpoint temperature is another property that is used for selection and / or modification of embodiments of the marine fuel compositions. As previously described, the "wax endpoint temperature" is the temperature at which essentially all (98 wt.% or more) of the wax in the marine fuel composition is melted. The marine fuel composition has a wax endpoint temperature of 70 °C to 130 °C, about 80 °C to 130 °C, about 90 °C to 130 °C, about 100 °C to 130 °C, about 110 °C to 130 °C, or about 120 °C to 130 °C. Selection and / or modification of an appropriate wax endpoint temperature in combination with KV50 and wax flow viscosity provides an ability for the marine fuel compositions to meet viscosity requirements from engine manufacturers while also being essentially free of solid wax during injection into the engine. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate wax endpoint temperature for embodiments of the marine fuel compositions, as desired for a particular application.EXAMPLES

[0028] To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the entire scope of the invention. ASTM Test Method D341 was used as the reference for the correlation between viscosity and temperature.Example 1

[0029] In this example, ten different heavy gas oils and ten different lighter gas oils were used to prepare several different sample marine fuel compositions, identified as Fuels 1-27. Fuels 1, 2, and 19 are according to the invention, the other Fuels are comparative examples. Table 1 below shows the properties of the different heavy and lighter gas oils used in this example, identified as LGOs and HGOs. Table 2 below shows the properties of the sample marine fuel compositions with acceptable wax flow viscosities (i.e., a ratio of KV50 to wax flow viscosity of greater than 1). As illustrated, Fuels 1-19 have a KV50 that is greater than the wax flow viscosity, indicating an acceptable wax flow viscosity. Table 3 below shows the properties of the different sample marine fuel compositions with unacceptable wax flow viscosities. As illustrated, Fuels 20-27 have a KV50 that is less than the wax flow viscosity, indicating an unacceptable wax flow viscosity. Table 1 Blend Component Density, g / cm 3< Viscosity at 50 °C, cSt Sulfur, wt.% Distillation T10, °C Distillation T50, °C Distillation T90, °C Distillation Method Wax content (wt.%) Wax Endpoint, °C (0% residual wax) Wax Flow Viscosity (predicted), cSt LGO A1 0.874918.620.0005306.2376.2399.9D8635LGO A2 0.923648.20.3144339466632D7169not testedLGO A3 0.906864.30.2284339466632D71692.56418.3LGO B1 0.83901.90.0053201250.8324D86not testedLGO B2 0.85002.600.004224.5280.5347.1D288710.5205.3LGO B3 0.85484.270.0526229325400D86not testedLGO C1 0.99852.001.13222243289D86not testedLGO C2 0.97958.891.15320.6346.9370.7D86not testedLGO C3 0.939319.600.77359.5419460.5D28878.65012LGO C4 0.88301.6910.098204262.4318.7D861.6513.4HGO A1 1.00002000001.2not testednot testednot testednot testedHGO A2 0.9732593.701.34326582727D2887105HGO A3 0.93285750.5109324610731D7169not testedHGO A4 0.971518780.71not testednot testednot testednot testedHGO A5 0.93959410.68299607705D6352not testedHGO A6 0.977930202.38476613729D2887104HGO A7 1.0047084320.81569659D6352not testedHGO B1 0.935925.510.17351440D8613.54911.6HGO B2 0.922725.680.14350424.5D8614.35012HGO B3 0.992450.001.7not testednot testednot tested6.66217.2 Table 2 Fuel Blend Recipe, vol % Density @ 15 °C, g / cm 3< Sulfur, wt% Viscosity KV50, cSt Wax content (wt%) Wax Endpoint, °C (0% residual wax) Wax Flow Viscosity (predicted), cSt Fuel 1 HGO A4, 580.90190.424930.31.88029.6LGO B1, 42Fuel 2 HGO A5, 680.90690.48453.72.38334.5LGO B1, 32Fuel 3 HGO A1, 410.94340.8566.89962LGO B2, 30LGO C3, 22Fuel 4 HGO A6, 67.30.94921.87210065LGO C1, 12Fuel 5 HGO A2, 1.360.87450.035111.51358LGO A1, 76LGO B3, 22LGO C2, 0.64Fuel 6 HGO A2, 1.360.880.03420.18358LGO A1, 98LGO C2, 0.64Fuel 7 HGO A2, 3.40.89730.33911.61358LGO A1, 58LGO B3, 18LGO C2, 20.6Fuel 8 LGO A1, 1000.87490.000518.62358Fuel 9 HGO A1, 37.20.939650.915.78134.8HGO B3, 14LGO B2, 35.78LGO C3, 10.54Fuel 10 HGO A1, 480.942588.155.548953.1LGO B2, 35.2LGO C3, 13.6Fuel 11 HGO A6, 750.93321.1579.89648LGO B3, 25LGO B2, 5Fuel 12 HGO A7, 750.94100.44521210065LGO B3, 25Fuel 13 HGO A6, 620.95996198.561LGO B3, 14LGO C1, 24Fuel 14 HGO A4, 800.92730.46183523.38052.6LGO A3, 42Fuel 15 HGO A4, 410.90830.322466.63.07328.1LGO A3, 47LGO B1, 12Fuel 16 HGO A4, 280.90840.291467.11.97126.3LGO A3, 65LGO B1, 7Fuel 17 HGO A1, 45.60.937666.684.28949LGO B2, 38.44LGO C3, 12.92Fuel 18 HGO A1, 39.60.934448.338.58134.8HGO B3, 7LGO B2, 39.54LGO C3, 11.22Fuel 19 HGO A2, 16.40.91540.430023.32.87123.0LGO A2, 64.7LGO B1, 18.9 Table 3 FUEL Blend Recipe, vol % Density @ 15 °C, g / cm 3< Sulfur, wt% Viscosity KV50, cSt Wax content (wt%) Wax Endpoint, °C (0% residual wax) Wax Flow KV50 (predicted), cSt Fuel 20 HGO A1, 31.80.932833.434.88536.1HGO B3, 17LGO B2, 40.07LGO C3, 9.01Fuel 21 HGO A1, 25.80.924520.577.38129.0HGO B3, 20LGO B2, 45.17LGO C3, 7.31Fuel 22 HGO A1, 170.89010.387.8424.28740LGO B2, 70LGO C3, 10Fuel 23 HGO A1, 110.88440.36.09722.78740HGO B3, 6LGO B2, 75LGO C3, 6Fuel 24 HGO A2, 240.90950.50746.94.49553LGO A1, 65LGO C2, 11Fuel 25 HGO A6, 15.20.89440.76912.418.17829LGO B3, 77.4LGO B2, 2.7Fuel 26 HGO A6, 8.70.87670.288.88519.37224LGO B3, 87LGO B2, 1.6Fuel 27 HGO A1, 42.60.930743.894.48944.4LGO B2, 42.49LGO C3, 12.07 Example 2

[0030] In this example, the wax endpoint temperature of comparative Fuels 10 and 21 were determined. To determine the wax endpoint temperature, differential scanning calorimetry ("DSC") was performed on each sample. The heat flow as a function of temperature from the DSC is provided as FIG. 2. The point where each curve reaches an asymptote and returns to the baseline is wax endpoint temperature. For Fuel 10, the wax endpoint temperature was identified to be 89 °C. Assuming a minimum operational viscosity at 89 °C of 8 cSt, this minimum operational viscosity can be converted to a wax flow viscosity of 53.1 cSt at 50 °C. As indicated in Table 2 above, the KV50 of Fuel 10 is 88.15 cSt. Because the ratio of the measured KV50 to the wax flow viscosity is greater than 1, the wax flow viscosity for Fuel 10 is acceptable. For Fuel 21, the wax endpoint temperature was identified to be 81 °C. Assuming a minimum operational viscosity at 81°C of 8 cSt, this minimum operational viscosity can be converted to a wax flow viscosity of 29.0 cSt at 50 °C. As indicated in Table 3 above, the KV50 of Fuel 21 is 20.57 cSt. Because the ratio of the measured KV50 to the wax flow viscosity is less than 1, the wax flow viscosity for Fuel 21 is unacceptable.

Claims

1. A marine fuel composition having low sulfur content, the marine fuel composition having the following enumerated properties: a sulfur content of 0.40 % to 0.49 % by weight of the marine fuel composition; a density at 15 °C of 0.86 g / cm3 to 0.95 g / cm3; a kinematic viscosity at 50 °C of 10 centistokes to 80 centistokes; and a wax endpoint temperature of 70 °C to 130 °C, said temperature being the temperature at which 98 wt% or more of wax contained by said liquid fuel has melted at atmospheric pressure, as determined via Differential Scanning Calorimetry.

2. A method of blending marine fuel compositions, comprising: blending two or more hydrocarbon components to prepare a liquid fuel, wherein the two or more hydrocarbon components comprise a heavy gas oil and a lighter gas oil, wherein at least 50 wt.% of the heavy gas oil boils at 500 °C to 750 °C, and wherein at least 50 wt.% of the lighter gas oil boils at 200 °C to 550 °C; and wherein the liquid fuel has the following enumerated properties: a sulfur content of 0.40 % to 0.49 % by weight of the marine fuel composition; a density at 15 °C of 0.86 g / cm3 to 0.95 g / cm3; a kinematic viscosity at 50 °C of 10 centistokes to 80 centistokes; and a wax endpoint temperature of 70 °C to 130 °C, said temperature being the temperature at which 98 wt% or more of wax contained by said liquid fuel has melted at atmospheric pressure, as determined via Differential Scanning Calorimetry.

3. The method of claim 2, wherein the heavy gas oil has a sulfur content of 0.50 wt.% to 3 wt.%, wherein the lighter gas oil has a sulfur content of 0.0001 wt.% to 0.05 wt.%, wherein the heavy gas oil as a kinematic viscosity at 50 °C of 30 centistokes or greater, wherein the lighter gas oil has a kinematic viscosity at 50 °C of 1 centistokes to 30 centistokes, wherein the heavy gas oil is present in an amount of 1 vol.% to 60 vol.%, and wherein the lighter gas oil is present in an amount of 40 vol.% to 99 vol.%.

4. The method of claim 2, comprising monitoring the viscosity and wax content of the liquid fuel.