AU2005338280B2

AU2005338280B2 - Improved fuel efficiency for trunk piston four-stroke diesel engines

Info

Publication number: AU2005338280B2
Application number: AU2005338280A
Authority: AU
Inventors: Klaus-Werner Damm; Richard Leahy
Original assignee: AP Moller Maersk AS
Current assignee: AP Moller Maersk AS
Priority date: 2005-11-21
Filing date: 2005-11-21
Publication date: 2010-02-11
Anticipated expiration: 2025-11-21
Also published as: WO2007057007A1; CN101321933B; BRPI0520703A2; CA2630171A1; CN101321933A; NO20082409L; HK1124648A1; AU2005338280A1

Description

WO 2007/057007 PCT/DK2005/000740 Improved fuel efficiency for trunk piston four-stroke diesel engines. FIELD OF THE INVENTION The invention relates to a system for reducing fuel consumption in a four 5 stroke trunk piston diesel engine. Further, the invention relates to a method of reducing fuel consumption in a four-stroke trunk piston diesel engine. BACKGROUND OF THE INVENTION Diesel engines used onboard certain types of vessels and/or used in certain 10 stationary applications are typically of the well known two-stroke type or of the well known four-stroke type. Two-stroke cross-head engines used in marine and/or stationary applications are equipped with two separate lubricating oil systems. One lubricating 15 system comprises so-called system oil/system lubricant that normally is used for lubrication and cooling of the engine's bearings and e.g. oil-cooled pistons as well as for activation and/or control of various valves or the like. The other lubricating system comprises an all-loss lubricant (cylinder oil/cylinder lubricant) that normally is used for lubrication of the engine's cylinders, piston 20 rings and piston skirt. Four-stroke trunk piston diesel engines, however, typically use only a single oil type for lubrication and cooling. Such engines are typically used as secondary/auxiliary or propulsion engines on ships, or in stationary power 25 generation or liquid/gas transmission applications. Such oils typically have a SAE viscosity of about 30 or 40. Trunk piston engine oils are constantly affected by exposure to the combustion process whereby the useful properties of the trunk piston engine 30 oil is degraded over time as the oil become more and more spent until finally the oil will have to be either replenished or completely changed. This degradation process cannot be reversed or halted by separators or the like. Contaminations caused by engine and part wear, particle pollution (e.g. from 35 combustion by-products), oxidation, hydrolysis, etc. further degrade the quality of the oil over time in addition to the oil degrading simply from being 2 used, which speeds up the degradation process. The degradation process in effect increases the viscosity of the engine oil. A diesel engine's frictional loss is mainly of a viscose character. An increase in the viscosity of the engine oil will therefore result in diminished operating efficiency, increased fuel 5 consumption, decreased engine efficiency, increased component wear and increased emissions. The performance level of the oil is typically measured periodically and may not go beyond certain limits if the oiled component's condition should not be 10 jeopardized. When the engine oil is approaching its condemning limit it will have to be replenished or changed. Changing the oil is usually done by de bunkered the oil, which is a costly process, or storing the oil as waste for later burning resulting in emissions. 15 To prolong the usable time of oils used in such engines, suited additives and/or additive packages are added to the base oil in order to obtain a fully formulated oil. Such blending is typically done at dedicated land based blend plants and the fully formulated oil has to the delivered to a ship or an off shore plant for use in the engines. The addition of additives or additive 20 packages increases the cost of the engine oil significantly. Patent application WO 02/087726 Al discloses an auxiliary filtration system and filtering method where the auxiliary filtration system consists of an auxiliary filtration device, an integral oil transfer pump controlled by an 25 electric motor being controlled by an control unit, an electronic pressure sensor, and fluid conductors. Engine oil is pumped from an oil pan of the engine through an auxiliary filter before it is returned to the oil pan of the engine e.g. through an optional 30 cooler. An electrostatic agglomeration system may be used to enhance the ability of -a filtering media.

-2a The system may also include an additive replenishment system supplying additives to the filtering media to enhance the quality of the oil. Alternative methods of additive replenishment involves applying a special chemical coating to the filtering media or mounting a replaceable and recyclable additive 5 releasing cartridge onto a return line. SUMMARY OF THE INVENTION The present invention provides a system for and a corresponding method of reducing fuel consumption in a trunk piston diesel engine that mitigates the io above-mentioned (and other) shortcomings. In accordance with the invention there is provided a four-stroke trunk piston diesel engine comprising a system for reducing fuel consumption, the system comprising: 15 * a replenishment system connected to receive oil from the engine and replenishment oil, where the oil replenishment system is configured for mixing the engine oil and the replenishment oil, the resulting a mixed oil being introduced into the engine, e wherein the replenishment system comprises a mixing unit receiving the 20 replenishment oil and the engine oil and mixing them according to a predetermined rate resulting in the mixed oil. There is further provided a method for reducing fuel consumption in a four stroke trunk piston diesel engine, the method comprising: 25 0 receiving engine oil from an engine in an oil replenishment system, e receiving replenishment oil in the oil replenishment system, and * mixing the engine oil and the replenishment oil, e introducing the mixed oil into the engine, wherein the oil replenishment system comprises a mixing unit and mixes the 30 replenishment oil and the engine oil according to a predetermined rate resulting in the mixed oil. Since the degradation process of the engine oil effectively is slowed by replenishing it the above mentioned adverse effects of the degradation process 35 are reduced or slowed or even avoided in a simple way. Thus, the 2122038_1 (GHMatlers) -3 replenishment system provides enhanced and consistent performance of the initial engine oil resulting in greatly reduced component wear and equipment lifecycle cost. Even further, a more environmentally friendly system is provided since less waste in the form of spent oil is produced as the usability period of s time for the engine oil is prolonged. The efficiency of the engine may also increase as it in a longer period of time uses oil having a lower viscosity. 10 Further, the addition of a replenishment system according to the present invention only requires minor adaptation of existing systems. In one embodiment, the replenishment system comprises a mixing unit receiving the replenishment oil and the engine oil and mixing them according to 15 a predetermined rate resulting in the mixed oil. In one embodiment, the replenishment system is configured for mixing the engine oil and the replenishment oil on a continuous, near-continuous or intermittent basis. 20 In one embodiment, the replenishment system is configured for introducing the mixed oil to the engine on a continuous, near-continuous or intermittent basis. In one embodiment, a rate for mixing the engine oil and the replenishment oil is 25 dependent on at least one measured actual condition of the oil, where the rate of mixing is automatically adjusted in response to the at least one actual condition of the oil. In one embodiment, the replenishment oil comprises one or more additives 30 and/or additive packages comprising one or more selected from the group of a Calcium detergent, an alkali metal detergent, an alkali-earth metal detergent, an anti-wear additive, a dispersant, a friction modifier, and anti-oxidants. In one embodiment, the engine is used in marine or stationary applications. 35 2122038_1 (GHMaters) -4 In one embodiment, the engine is used offshore, on-site or in a land based plant. In one embodiment, the replenishment oil is selected from the group of: 5 - a heavy fuel oil, - bunker oil, and - residual fuel oil. Advantageous embodiments of the method according to the present invention 10 are defined in the sub-claims and described in detail in the 2122036_1 (GHMatlers) WO 2007/057007 PCT/DK2005/000740 5 following. The embodiments of the method correspond to the embodiments of the system and have the same advantages for the same reasons. BRIEF DESCRIPTION OF THE DRAWINGS 5 These and other aspects of the invention will be apparent from and elucidated with reference to the illustrative embodiments shown in the drawing, in which: Figure 1 illustrates a schematic block diagram of a prior art four-stroke trunk 10 piston engine system; Figure 2 illustrates a schematic block diagram of a four-stroke trunk piston engine system according to one embodiment of the present invention; and 15 Figure 3 illustrates a schematic block diagram of a preferred embodiment of a replenishment system according to one embodiment of the present invention. DESCRIPTION OF PREFERRED EMBODIMENTS 20 Figure 1 illustrates a schematic block diagram of a prior art four-stroke trunk piston engine system. Shown is a typical prior art four-stroke trunk piston engine (100) connected to its oil system responsible for cycling oil through the engine during use thereby cooling and lubricating the engine (100) and other parts of the system. 25 Oil being tapped from the engine (100) is typically passed through a first filter (110) by a pump (not shown) or the like where the filter (110) is responsible for removing small particles, insolubles, wear debris, etc. from the oil. After this, the oil is passed to an engine oil container (101) or the like. Connected 30 to the oil container (101) is a separator or filter (111) (forth only denoted separator) that receives some of the oil from the container (101) and removes dirt, wear debris from engine components, water caused by hydrolysis, etc. typically by spinning. The separator (111) may also remove unwanted chemical compounds like CaSo4, etc. The resulting unwanted 35 materials are removed from the system as waste or sludge.

6 Oil is taken from the oil container (101) and passed through another filter (112) removing small particles, insolubles, debris, etc. and water and other materials of different density SG e.g. the same or, as preferred, a different 5 technique (e.g. using a centrifuge mechanism) than the first filter (110) before being introduced into the engine (100) for use again. As mentioned earlier, the oil is degraded by this process causing decreased engine efficiency, increased fuel consumption, etc. When the oil is 10 approaching its condemning limit it will have to be replenished or changed and is discarded as waste and stored for later de-bunkering or burning. Figure 2 illustrates a schematic block diagram of a four-stroke trunk piston engine system according to one embodiment of the present invention. The 15 illustrated system comprises a four-stroke diesel piston engine (100), a first filter (110), an oil container (101), a separator (111) and another filter (112) connected and , corresponding to the ones shown and described in connection with Figure 1. 20 Further shown is a replenishment system (102) according to an embodiment of the present invention. The replenishment system (102) is connected to receive some of the engine oil after leaving the engine (100) e.g. via a three way valve (113) or some other flow and/or rate controlling means. 25 Preferably, the replenishment system (102) receives engine oil after it has proceeded through the separator (111) so it is cleaner than if it was tapped directly from the oil container (101). Alternatively, the replenishment system (102) could receive engine oil directly from the oil container (101) whereby the three-way valve (113) is not needed or from another place in the engine 30 system. The replenishment system (102) mixes replenishment oil (120) (e.g. heavy fuel oil (HFO), residual fuel oil, bunker- oil or the like) received from an 6a adequate source (like a container, tank or the like) with the received engine oil thereby creating a mix of oil (103) that effectively is less spent as it is mixed with fresh or fresher oil. The mixed oil (103) is then introduced into the engine in 7 addition to the engine oil being introduced normally as described in connection with Figure 1 from the oil container (101). The mixed oil (103) may be, supplied to the engine (100) on a continuous, 5 near-continuous or intermittent basis. In one embodiment, the replenishment oil (120) (HFO, residual fuel oil, bunker oil, etc.) also comprises one or more additives and/or additive packages. The additives may e.g. comprise a Calcium detergent, alkali 10 metal(s) detergent(s), alkali-earth metal detergent(s), anti-wear additives, dispersants, friction modifiers, anti-oxidants, etc. improving the engine/system condition and/or efficiency in some way or another. The replenishment system (102) may be configured for mixing the engine oil 15 and the replenishment oil (120) on a continuous, near-continuous or intermittent basis. Since the degradation process of the engine oil effectively is slowed by replenishing it the above mentioned adverse effects of the degradation 20 process are reduced or slowed or even avoided. Thus, the replenishment system provides enhanced and consistent performance of the initial engine oil resulting in greatly reduced component wear and equipment lifecycle cost. Even further, a more environmentally friendly system is provided since less waste in the form of spent oil is produced as the usability period of time for 25 the engine oil is prolonged. Further, the normal engine oil need not contain so many additives since it is replenished whereby cheaper engine oil (since it do not need to contain additives or additive packages) can be used without compromising the 30 efficiency of the engine. The efficiency of the engine is also increased as it in a longer period of time uses oil having a lower viscosity.

7a Further, the addition of a replenishment system according to the present invention only requires minor adaptation of existing systems.

WO 2007/057007 PCT/DK2005/000740 8 The engine (100) according to the present invention can e.g. be used in marine or stationary applications, both on-shore and off-shore. 5 Figure 3 illustrates a schematic block diagram of a preferred embodiment of a replenishment system according to one embodiment of the present invention. Shown is an engine system corresponding to the one in Figure 2 with the addition of a more detailed embodiment of the replenishment system (102). In this embodiment, the replenishment system (102) comprises a io mixing or blending unit (114) (forth only referred to as mixing unit) or the like that receives the engine oil via the three way valve (113) from the separator (111) (or alternatively directly from the oil container (101) and fresh (or at least less spent oil than the engine oil) heavy fuel oil (HFO), bunker oil, residual fuel oil, etc. The mixing unit (114) mixes the HFO and the spent 15 engine oil resulting in the less spent mixed oil (113) that is introduced into the engine (100). The mixing unit (114) can be any standard mixing unit capable of mixing oils at the required rates 20 In a preferred embodiment, the rate of mixing is dependent on at least one measured actual condition of the oil. The measured condition could e.g. be the pollution level or condemning level of the engine oil. In a preferred embodiment, the rate of mixing is automatically adjusted in response to at 25 least one actual condition of the oil that preferably also is measured automatically and provided to the mixing unit (114). A holding tank (104) or the like may be inserted between the mixing (114) and the rest of the engine system (101/111). This holding tank (104) may act 30 as a reservoir of engine oil coming from the separator (111). This may be useful if the rate of introducing the mixed oil (113) into the engine is not the same as the rate of engine oil passing through the separator (111). Further, since additional oil is added to the system thereby increasing the total volume of oil it may be necessary to have extra storage capacity if the oil container 35 (101) is not of an adequate size.

9 An additional tank (105) may also be inserted after the mixing unit (114) for holding the mixed oil (113) before it is introduced into the engine (100). The additional tank (105) may e.g. be a 'day' or holding tank that is emptied into the engine whenever operations requires it, which simplifies the process of 5 introducing the mixed oil (103) into the engine. Other rates of introducing the mixed oil (113) into the engine may be just as applicable. In this way, the typical degradation process of the engine oil is slowed by replenishing it the adverse effects associated with the degradation process 10 are reduced or slowed or even avoided in a very simple way. Thus, the replenishment system provides enhanced and consistent performance of the initial engine oil resulting in greatly reduced component wear and equipment lifecycle cost. Even further, a more environmentally friendly system is provided since less waste in the form of spent oil is produced as the usability 15 period of time for the engine oil is prolonged. Additionally, great economical savings and environmental improvements are achieved. In the claims, any reference signs placed between parentheses shall not be constructed as limiting the claim. The word "comprising" does not exclude the 20 presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. It is to be understood that, if any prior art publication is referred to herein, 25 such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. N:\Melbourne\Cases\Patent\77000-77999\P77770.AU\Specis\P77770.AU_2005-11-21 DHE P200500744 _EP - Final.doc

Claims

1. A four-stroke trunk piston diesel engine comprising a system for reducing fuel consumption, the system comprising: 5 e a replenishment system connected to receive oil from the engine and replenishment oil, where the oil replenishment system is configured for mixing the engine oil and the replenishment oil, the resulting a mixed oil being introduced into the engine, . wherein the replenishment system comprises a mixing unit receiving 10 the replenishment oil and the engine oil and mixing them according to a predetermined rate resulting in the mixed oil.

2. A four-stroke trunk piston diesel engine according to claim 1, wherein the oil replenishment system is configured for mixing the engine oil and the 15 replenishment oil on a continuous, near-continuous or intermittent basis.

3. A four-stroke trunk piston diesel engine according to claim 1 or 2, wherein the oil replenishment system is configured for introducing the mixed oil to the engine on a continuous, near-continuous or intermittent basis. 20

4. A four-stroke trunk piston diesel engine according to any one of claims 1 3, wherein a rate for mixing the engine oil and the replenishment oil is dependent on at least one measured actual condition of the oil, where the rate of mixing is automatically adjusted in response to the at least one actual 25 condition of the oil.

5. A four-stroke trunk piston diesel engine according to any one of claims 1 4, wherein the replenishment oil comprises one or more additives and/or additive packages comprising one or more selected from the group of a 30 Calcium detergent, an alkali metal detergent, an alkali-earth metal detergent, an anti-wear additive, a dispersant, a friction modifier, and anti-oxidants.

6. A four-stroke trunk piston diesel engine according to any one of claims 1 5, wherein said engine is used in marine or stationary applications. 35 N:\Melbourne\Cases\Patent\77000-77999\P77770.AU\Specis\P77770.AU_2005-11-21 DHE P200500744 _EP - Final.doc 11

7. A four-stroke trunk piston diesel engine according to any one of claims 1 6, wherein said engine is used offshore, on-site or in a land based plant.

8. A four-stroke trunk piston diesel engine according to any one of claims 1 5 7, wherein the replenishment oil is selected from the group of: - a heavy fuel oil, - bunker oil, and - residual fuel oil. 10

9. A method for reducing fuel consumption in a four-stroke trunk piston diesel engine, the method comprising: * receiving engine oil from an engine in an oil replenishment system, e receiving replenishment oil in the oil replenishment system, and " mixing the engine oil and the replenishment oil, 15 e introducing the mixed oil into the engine, wherein the oil replenishment system comprises a mixing unit and mixes the replenishment oil and the engine oil according to a predetermined rate resulting in the mixed oil. 20

10. A method according to claim 9, wherein the oil replenishment system mixes the engine oil and the replenishment oil on a continuous, near continuous or intermittent basis.

11. A method according to claim 9 or 10, wherein the oil replenishment 25 system introduces the mixed oil to the engine on a continuous, near continuous or intermittent basis.

12. A method according to any one of claim 9 - 11, wherein a rate for mixing the engine oil and the replenishment oil is dependent on at least one 30 measured actual condition of the oil, where the rate of mixing is automatically adjusted in response to the at least one actual condition of the oil.

13. A method according to any one of claims 9 - 12, wherein the replenishment oil comprises one or more additives and/or additive packages 35 comprising one or more selected from the group of a Calcium detergent, an N:\Melbourne\Cases\Patent\77000-77999\P77770.AU\Specis\P77770.AU_2005-11-21 DHE P200500744 _EP - Final.doc 12 alkali metal detergent, an alkali-earth metal detergent, an anti-wear additive, a dispersant, a friction modifier, and anti-oxidants.

14. A method according to any one of claims 9 - 13, wherein said engine is 5 used in marine or stationary applications.

15. A method according to any one of claims 9 - 14, wherein said engine is used offshore, on-site or in a land based plant. 10

16. A method according to any one of claims 9 - 15, wherein the replenishment oil is selected from the group of: - a heavy fuel oil, - bunker oil, and - residual fuel oil. 15

17. A four-stroke trunk piston diesel engine, substantially as herein described with reference to Figures 2 and 3.

18. A method for reducing fuel consumption in a four-stroke piston diesel 20 engine substantially as herein described with reference to Figures 2 and 3. N:\Melbourne\Cases\Patent\77000-77999\P77770.AU\Specis\P77770.AU_2005-11-21 DHE P200500744 _EP - Final.doc