Novel Fuel Compositions And Methods For Making Same

CATEGORY: BUNKER FUEL
PATENT
Novel Fuel Compositions And Methods For Making Same
United States Patent Application 20120246999
Inventors:
Stern, David L. (Fairfax, VA, US)
Di Mauro, Salvatore R. (Fairfax, VA, US)
Roccaro, Aldo (Legnano, IT)
Bessonette, Paul W. (Deptford, NJ, US)
Application Number:
13/431050
Publication Date:
10/04/2012
Assignee:
Exxonmobil Research And Engineering Company (Annandale, Nj, Us)
Abstract:
This invention relates to low sulfur marine/bunker fuel compositions and methods of making same. Contrary to conventional marine/bunker fuel compositions/methods, the inventive lower sulfur compositions/methods focus on use of mostly uncracked components, such as (cat feed) hydrotreated gasoils, and/or can also have reduced contents of residual components.
FIELD
This invention relates generally to methods for making marine/bunker fuels having relatively low sulfur content, as well as to the resulting low sulfur content fuel compositions made according to such methods.
BACKGROUND
As promulgated by the International Maritime Organization (IMO), issued as Revised MARPOL Annex VI, marine fuels will he capped globally with increasingly more stringent requirements on sulfur content. In addition, individual countries and regions are beginning to restrict sulfur level used in ships in regions known as Emission Control Areas, or ECAs.
The fuels used in global shipping are typically marine/bunker fuels, for larger ships. Bunker fuels are advantageous since they are less costly than other fuels; however, they are typically composed of cracked and/or resid fuels and hence have higher sulfur levels. Meeting the lower sulfur specs for marine vessels can be conventionally accomplished through the use of distillates. However, distillate fuels typically trade at a high cost premium for a variety of reasons, not the least of which is the utility in a variety of transport applications employing Compression ignition engines. They are produced at low sulfur levels, typically significantly below the sulfur levels specified in the IMO regulations.
Those regulations specify, inter alia, a 1.0 wt % sulfur content on ECA Fuels (effective July, 2010) for residual or distillate fuels, a 3.5 wt % sulfur content cap (effective January, 2012), which can impact about 15% of the current residual fuel supply, a 0.1 wt % sulfur content on ECA Fuels (effective January, 2015), relating mainly to hydrotreated middle distillate fuel, and a 0.5 wt % sulfur content cap (circa 2020-2025), centered mainly on distillate fuel or distillate/residual fuel mixtures. When the ECA sulfur limits and sulfur cap drops, various reactions may take place to supply low sulfur fuels. The 0.1% S ECA fuel can he challenging to supply, since shippers typically purchase lower sulfur fuel oils with properties suitable for marine applications, and at a steep price discount to distillate fuels.
Hydrotreaters in front of FCC units, commonly called CFHT, typically hydroprocess Virgin Gas Oils (VGOs) to sufficiently low sulfur levels such that the product fuels are sufficient to he sold as fuel with no further treatment, or with minimal incremental hydroprocessing.
It would be advantageous to utilize a fuel high energy content, low sulfur fuels in marine applications, which fuels have conventionally included cracked distillates. Distillates can typically command a much higher value than bunker fuels. An alternative low sulfur marine/bunker fuel, with the correct fuel quality characteristics, could command a high premium in the marketplace.
Indeed, there are some publications that disclose the desirability of lowering the sulfur content of marine/bunker fuels. A non-exclusive list of such publications includes, for example, U.S. Pat. Nos. 4,006,076, 4,420,388, 6,187,174, 6,447,671, and 7,651,605, U.S. Patent Application Publication No. 2008/0093262, PCT Publication Nos. WO 1999/057228 and WO 2009/001314, British Patent No. GB 1209967, Russian Patent No. RU 2213125, Japanese Patent No. JP 2006000726, and the following articles: Chem. & Tech. of. Fuels and Oils (2005), 41(4), 287-91; Ropa a Uhlie (1979), 21(8), 433-40; Godishnik na Visshya Khim. heski Institut, Sofiya (1979), 25(2), 146-48; and Energy Progress (1986), 6(1), 15-19.
Thus, it would be desirable to find compositions and methods for making them) in which hydrotreated and/or untracked gasoil products could he used in marine/bunker fuels, as described with reference to the invention herein.
SUMMARY OF EMBODIMENTS OF THE INVENTION
One aspect of the invention relates to a method for making a low sulfur marine and/or bunker fuel composition with a reduced concentration of components that have been cracked, the method comprising: contacting a gasoil feed stream having at least 7500 wppm, for example at least 2000 wppm, sulfur content with a hydrogen-containing gas in the presence of a hydrotreating catalyst under effective hydrotreating conditions in a catalytic feed hydrotreater, such that the product exhibits at most 5000 wppm, for example at most 1000 wppm, sulfur content, a pour point of at least 7° C., and a kinematic viscosity of at least 12 cSt at about 50° C., without the product being subject to cracking; optionally blending at least a portion of the uncracked product with 0-70 vol % of other components, selected from viscosity' modifiers, pour point depressants, lubricity modifiers, antioxidants, and combinations thereof, to form a marine and/or bunker fuel composition, the resulting marine and/or bunker fuel composition containing the uncracked product having: at most 5000 wppm, for example at most 1000 wppm, sulfur content; at most 25 vol %, based on all components of the marine and/or bunker fuel composition, of residual components selected from crude fractionation vacuum resid, crude fractionation atmospheric resid, visbreaker resid, deasphalted vacuum resid, slurry oil, and combinations thereof; less than 50 vol %, based on all components of the marine and/or bunker fuel composition, of residual components, components subject to a refinery cracking step, or both; and at least one of a kinematic viscosity at about 50° C. from 12 cSt to 50 cSt; a density at about 15° C. from 0.90 g/cm3 m to 0.94 g/c3, a pour point from 7° C. to 45° C., and a calculated carbon aromaticity index of 850 or less.
Another aspect of the invention relates to a low sulfur marine and/or bunker fuel composition comprising: 30 vol % to 100 vol % of an uncracked, hydrotreated gasoil product having at most 5000 wppm, for example at most 1000 wppm, sulfur content, a pour point of at least 7° C., and a kinematic viscosity of at least 12 cSt at about 50° C.; and up to 70 vol % of other components, selected from viscosity modifiers, pour point depressants, lubricity modifiers, antioxidants, and combinations thereof, wherein the low sulfur marine and/or bunker fuel composition has: at most 5000 wppm, for example at most 1000 wppm, sulfur content; at most 25 vol %, based on all components of the marine and/or bunker fuel composition, of residual components selected from crude fractionation vacuum resid, crude fractionation atmospheric resid, visbreaker resid, deasphalted vacuum resid, slurry oil, and combinations thereof; less than 50 vol %, based on all components of the marine and/or bunker fuel composition, of residual components, components subject to a refinery cracking step, or both; and at least one of a kinematic viscosity at about 50° C. from 12 cSt to 50 cSt, a density at about 15° C. from 0.90 g/cm3 to 0.94 g/cm3, a pour point from 7° C. to 45° C., and a calculated carbon aromaticity index of 850 or less.
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