Patent Application
20140290610
Exemplary embodiments disclosed herein generally relate to diesel engines, and more particularly, to deoxygenation of a diesel fuel configured for use in a diesel engine.
Recent advancements in injector technology are responsible for improvements in emissions and power density of diesel engine systems. Such advancements have been achieved through a combination of reduced nozzle orifice diameters, reduced cavitation, and increased temperatures at the nozzle tip.
Carbonatious deposits are common in diesel engine systems, and particularly in advanced diesel systems operating at high temperatures, because increased temperatures accelerate the formation of such deposits. As a result of the reduction in the diameter of the nozzle orifice, the effect of the carbonatious deposits is even more pronounced. Additionally, the reduced cavitation in advanced diesel engine systems minimizes the self-cleaning mechanism that prevents blockages from obstructing the passages in the nozzle, such that the power output of the advanced diesel engine system will significantly decrease over time. Carbonatious deposits may also form within the injector body, such as in the armature, the piston and nozzle needle, or inside the nozzle body for example. Therefore, the improvements in advanced diesel engine technology and the increased utilization of alternative, bio-fuels have, unfortunately, resulted in an increased propensity for carbonatious formation, and an increased susceptibility to problems resulting from the formation of such deposits.
According to one embodiment of the invention, a fuel system is provided including a diesel fuel reservoir configured to supply a diesel fuel having a first amount of dissolved oxygen. An adjacent diesel engine is arranged generally downstream from the diesel fuel reservoir. A deoxygenation system has an inlet fluidly coupled to the diesel fuel reservoir and an outlet fluidly coupled to the advanced diesel engine. The deoxygenation system is configured to remove dissolved oxygen from the diesel fuel. The diesel fuel provided to the advanced diesel engine has a second amount of dissolved oxygen. The second amount of dissolved oxygen is less than the first amount of dissolved oxygen.
According to another embodiment, a fuel system for a marine vessel is provided including at least one collecting tank configured to store diesel fuel containing a first amount of dissolved water, a first amount of non-miscible water, and a first amount of dissolved oxygen. A diesel fuel reservoir is arranged generally downstream from the at least one collecting tank. The diesel fuel reservoir is configured to store a diesel fuel having a first amount of dissolved oxygen, a first amount of dissolved water, and a second amount of non-miscible water. A purifier is fluidly coupled to the at least one collecting tank and the diesel fuel reservoir. The purifier is configured to remove non-miscible water from the diesel fuel. An advanced diesel engine is arranged generally downstream from the diesel fuel reservoir. A deoxygenation system has an inlet fluidly coupled to the diesel fuel reservoir and an outlet fluidly coupled to the advanced diesel engine. The deoxygenation system is configured to remove dissolved oxygen from the diesel fuel. The diesel fuel provided to the advanced diesel engine has a second amount of dissolved oxygen. The second amount of dissolved oxygen is less than the first amount of dissolved oxygen.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
An exemplary deoxygenation system 20 configured to remove oxygen from a fuel F flowing through the deoxygenation system 20 is schematically illustrated in
The permeable membrane 24 allows primarily dissolved oxygen and not larger fuel molecules, to diffuse through openings, such as voids or pores for example. Alternatively, or in conjunction with the openings, the permeable membrane 24 may utilize a solution-diffusion mechanism to dissolve and diffuse primarily oxygen through the membrane 24 while excluding the fuel F. The family of Teflon™ AF, which is an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole (PDD) often identified under the trademark “Teflon™ AF” registered to E. I. Dupont de Nemours of Wilmington, Del., and the family of HYFLON™ AD which is a copolymer of 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (TTD) registered to Solvay Solexis, Milan, Italy have proven to provide effective results for fuel deoxygenation. The Teflon™ AF 2400 and/or Teflon™ AF 1600 material is believed to use a solution-diffusion mechanism. Given this description, one of ordinary skill in the art will recognize other types of fluoropolymers or other polymer materials suitable for their needs as a permeable membrane 24.
Fuel F having naturally dissolved oxygen is provided to the inlet 28 of the deoxygenation system 20, and oxygen-depleted fuel F is discharged from the outlet 30 of the deoxygenation system 20. A vacuum port 29 is in communication with the permeable membrane 24. The fuel F flowing through the fuel channels 22 is in contact with the permeable membrane 24. A vacuum 31 (see
In one embodiment, the permeable membrane 24 allows dissolved water within the fuel F, in addition to dissolved oxygen, to diffuse through the openings of the membrane 24. In such embodiments, the partial pressure differential created across the membrane 24 by the vacuum 31 causes dissolved water and dissolved oxygen to migrate through the membrane and into the receiving channels 26 of the deoxygenation system 20.
The quantity of fuel channels 22 arranged within the deoxygenation system 20 is generally determined based on application-specific requirements, such as fuel type, fuel temperature, and mass flow demand for example. The configuration of the one or more fuel channels 22 within the deoxygenation system 20 may be designed to maximize exposure of the fuel F to the permeable membrane 24 to increase the amount of dissolved oxygen and/or dissolved water removed from the fuel F. In one embodiment, the surface area of the permeable membrane 24 is increased. In another embodiment, an active area of the permeable membrane 24 is exposed to a flow region where a dissolved oxygen or a dissolved water concentration is relatively high. In yet another embodiment, the fuel flow is mixed as it travels through the fuel channels 22. The deoxygenation system 20 described herein is exemplary, and other suitable deoxygenation systems configured to reduce the amount of dissolved oxygen in a fuel F flowing there through are within the scope of the invention.
Different fuels containing different amounts of dissolved oxygen may require different amounts of deoxygenation to remove a desired amount of dissolved oxygen. In one embodiment, the fuel F flowing through the fuel channels 22 of the deoxygenation system 20 is a diesel fuel configured for use in an advanced diesel engine. In general, advanced diesel engines employ high-pressure “common rail” injection technology which provides better fuel atomization, and therefore, improved emissions control. Exemplary diesel fuels that may be used in conjunction with advanced diesel engines include petroleum-derived diesel, bio-derived diesel, and any other suitable fuel known to a person having ordinary skill in the art.
Referring now to
In one embodiment, a strainer 52 and/or at least one filter 54 may be arranged generally downstream from the fuel reservoir 44, such as within conduit 46 for example. The strainer 52 and/or filter 54 remove debris particles equal to or greater than a predetermined size from the fuel flow. In one embodiment, the strainer 52 is configured to remove particles generally larger than a first size, and the one or more filters 54 are configured to remove particles generally larger than a second, smaller size.
As generally understood, the diesel fuel F stored within the fuel reservoir 44 is saturated with dissolved oxygen, for example at a level of approximately 70 ppm. The fuel pump 50 communicates with the reservoir 44, such as through a valve (not shown) for example, to supply fuel F to the inlet 28 of the deoxygenation system 20. As the fuel F passes through the deoxygenation system 20, oxygen is removed from the fuel using a vacuum 31 or sweep gas. The size and number of fuel channels 22 can be adjusted to remove the desired amount of dissolved oxygen depending on application needs. In one embodiment, the deoxygenation system 20 is sized for a minimum of 20% deoxygenation to a maximum of 90% deoxygenation, relative to the initial 70 ppm level of dissolved oxygen. The deoxygenated fuel F flows through the second conduit 48, from the outlet 30 of the deoxygenation system 20 to the energy conversion device 42, such as the fuel injector of an advance diesel engine. It should be understood that although a particular arrangement is disclosed in the illustrated embodiment, other arrangements are within the scope of the invention.
Referring now to
In one non-limiting embodiment, illustrated in
By decreasing the amount of oxygen in a diesel fuel F before it is provided to an advanced diesel engine, the rate of “auto-oxidation” reactions that cause coking and varnish are substantially reduced. As a result, the thermal stability of the diesel fuel F is improved.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
