Method and system for operating two-and four-stroke engines using low sulfur fuels

Abstract

A method for operating a two-stroke engine using low sulfur fuels. Blended cylinder oil is produced by blending base oil and at least one additive where the total base number (“TBN”) of the blended cylinder oil ranges from 1 TBN to 20 TBN. The engine is operated by supplying the blended cylinder oil and a fuel having less than 1.0% sulfur to the engine cylinders. The additive includes a low TBN calcium salts at a weight ratio ranging from 90:10 to 10:90; or any combination thereof. A method for operating a 4-stroke engine using low and high sulfur fuels. Blended oil, having a TBN that is greater than 20 TBN, is produced by blending base oil and at least one additive. The engine is operated by exchanging a low sulfur fuel having less than 1.0% sulfur with a high sulfur fuel. The engine lubricating system is switched to the blended cylinder oil in accordance with switching the fuel from a low sulfur fuel to a high sulfur fuel.

1 . A method for operating a two-stroke engine, comprising:
 (a) producing a blended cylinder oil having a total base number (TBN) ranging from 20 TBN to 1 TBN by blending a base oil and at least one additive; and   (b) operating the engine by supplying the blended cylinder oil and a fuel contains a sulfur content ranging from 1.0 wt. % sulfur to 0.001 wt. % sulfur to the engine cylinders.   
     
     
         2 . The method of  claim 1 , wherein the base oil is selected from the group consisting of system oil, used system oil, trunk piston engine oil, or used trunk piston engine oil. 
     
     
         3 . The method of  claim 2 , wherein the at least one additive is selected from the group consisting of detergents, anti-oxidants, and friction modifiers. 
     
     
         4 . The method of  claim 1 , wherein the fuel contains a sulfur content ranging from 0.5 wt. % sulfur to 0.001 wt. % sulfur. 
     
     
         5 . The method of  claim 1 , wherein the fuel corresponds to a Straight Vegetable Oil (SVO). 
     
     
         6 . The method of  claim 1 , wherein the two-stroke engine is operated on a marine vessel. 
     
     
         7 . The method of  claim 6 , wherein said blending is performed on the marine vessel. 
     
     
         8 . The method of  claim 6 , wherein said blending is not performed on the marine vessel. 
     
     
         9 . The method of  claim 1 , wherein the blended cylinder oil has a composition containing a base fluid of lubricating viscosity and a mixture of at least two of the following: a low (or non-overbased) TBN calcium phenate; a low (or non-overbased) TBN calcium sulphonate; a low (or non-overbased) TBN calcium salicylate, or any combination thereof, wherein the at least two additives have a weight ratio ranging from 90:10 to 10:90. 
     
     
         10 . The method of  claim 9 , wherein the blended cylinder oil composition has a TBN in the range of 1 TBN-15 TBN. 
     
     
         11 . The method of  claim 9 , wherein calcium phenate has a TBN from 20 TBN to 250 TBN. 
     
     
         12 . The method of  claim 9 , wherein the calcium phenate has a mole ratio of metal to phenate ranging from 0.2:1 to 1.5:1 for a Group IIA metal and ranging from 0.1:1 to 0.5:1 for a Group IIA metal. 
     
     
         13 . The method of  claim 9 , wherein the calcium sulphonate has a TBN from 10 TBN to 300 TBN. 
     
     
         14 . The method of  claim 9 , wherein the calcium sulphonate has a mole ratio of metal to phenate ranging from 0.1:1 to 2:1 for a Group IIA metal and ranging from 0.1:1 to 0.5:1 for a Group IIA metal. 
     
     
         15 . The method of  claim 9 , wherein the calcium salicylate has a TBN from 10 TBN to 200 TBN. 
     
     
         16 . The method of  claim 9 , wherein the calcium salicylate has a mole ratio of metal to phenate ranging from 0.1:1 to 2:1 for a Group IA metal and ranging from 0.1:1 to 0.5:1 for a Group IIA metal. 
     
     
         17 . A method for operating a 4-stroke engine, comprising:
 (a) producing a blended TPEO having a total base number (TBN) that is greater than 20 TBN by blending a base oil and at least one additive;   (b) operating the engine by exchanging a low sulfur fuel having a sulfur content ranging from 1.0 wt. % sulfur to 0.001 wt. % sulfur with a high sulfur fuel having a sulfur content ranging from 1.1 wt. % sulfur to 4.5 wt. % sulfur; and   (c) switching the engine lubricating system to the blended TPEO in accordance with the exchanging.   
     
     
         18 . The method of  claim 17 , wherein the base oil is selected from the group consisting of system oil, used system oil, trunk piston engine oil, or used trunk piston engine oil. 
     
     
         19 . The method of  claim 18 , wherein the at least one additive comprises at least one base. 
     
     
         20 . The method of  claim 19 , wherein the at least one base comprises basic salts of alkaline or earth alkaline elements, and/or detergents and/or dispersants. 
     
     
         21 . The method of  claim 17 , wherein the blended TPEO composition has a TBN in the range of 20-70 TBN. 
     
     
         22 . The method of  claim 17 , wherein the low sulfur fuel corresponds to a Straight Vegetable Oil (SVO). 
     
     
         23 . The method of  claim 17 , wherein the 4-stroke engine is operated on a marine vessel. 
     
     
         24 . The method of  claim 23 , wherein said blending is performed on the marine vessel. 
     
     
         25 . The method of  claim 23 , wherein said blending is not performed on the marine vessel. 
     
     
         26 . The method of  claim 17 , wherein blended TPEO has a composition containing a base fluid of lubricating viscosity and a mixture of at least two of the following metal-organic detergent additives: non-overbased or overbased TBN calcium phenate; a non-overbased or overbased TBN calcium sulphonate; non-overbased or overbased TBN calcium salicylate, or any combination thereof.