Cylinder lubricating oil composition for crosshead diesel engine equipped with scrubber

Abstract

A cylinder lubricating oil composition for a crosshead diesel engine equipped with a scrubber, including: a base oil; and (A) a metallic detergent, wherein the composition has a base number of 15 to 125 mgKOH/g, and a kinematic viscosity at 100° C. of 10 to 30 mm 2 /s; and the composition satisfies the requirement (i) or (ii): (i) the composition includes: (B) 0.02 to 5.0 mass % of a demulsifier; (ii) the composition includes, as the component (A), (A1) a Ca phenate detergent; and (A2) a metallic detergent other than Ca phenate; the composition optionally includes (C-1′) 0.015 mass % or less in terms of nitrogen of a succinimide dispersant or a borated derivative thereof; and the Ph value of the formula (1) is 20×10 −3 or less: Ph value= C Ca ×2/( r M ×40.08)  (1) wherein C Ca represents calcium content (mass %) derived from the component (A1), and r M represents a metal ratio of the component (A1).

1 . A cylinder lubricating oil composition for a crosshead diesel engine equipped with a scrubber, comprising:
 a base oil; and   (A) a metallic detergent,   wherein the lubricating oil composition has a base number of 15 to 125 mgKOH/g, and a kinematic viscosity at 100° C. of 10 to 30 mm 2 /s; and   the lubricating oil composition satisfies the following requirement (i) or (ii):   
       (i) the lubricating oil composition comprises:
 (B) a demulsifier in an amount of 0.02 to 5.0 mass % on the basis of the total mass of the composition; 
 
       (ii) the lubricating oil composition comprises, as the component (A),
 (A1) a Ca phenate detergent; and 
 (A2) a metallic detergent other than any Ca phenate detergent; 
 the lubricating oil composition optionally comprises: 
 (C-1′) a succinimide having at least one alkyl or alkenyl group in a molecule thereof, or a borated derivative thereof, in an amount of no more than 0.015 mass % in terms of nitrogen on the basis of the total mass of the composition; and 
 a Ph value represented by the following formula (1) is no more than 20×10 −3 :
   Ph value= C   Ca ×2/( r   M ×40.08)  (1)
 
 
 
       (in the formula (1), C Ca  represents calcium content (mass %) derived from the component (A1), and r M  represents a metal ratio of the component (A1).). 
     
     
         2 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (i); and   the lubricating oil composition comprises:   (C) a nitrogen-containing ashless dispersant.   
     
     
         3 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (i); and   the lubricating oil composition optionally comprises:   (C) a nitrogen-containing ashless dispersant in an amount of no more than 0.2 mass % in terms of nitrogen on the basis of the total mass of the composition.   
     
     
         4 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (i); and   the component (B) is one or more polyether compound.   
     
     
         5 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 4 ,
 wherein a number average molecular weight of the component (B) is no less than 500.   
     
     
         6 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (i); and   the component (A) is a Ca phenate.   
     
     
         7 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (ii); and   the lubricating oil composition comprises the component (C-1′) in an amount of greater than 0 mass % and no more than 0.015 mass % in terms of nitrogen on the basis of the total mass of the composition.   
     
     
         8 . The cylinder lubricating oil composition for the crosshead diesel engine equipped with the scrubber according to  claim 1 ,
 wherein the lubricating oil composition satisfies the requirement (ii); and   the component (A2) is a Ca sulfonate and/or a Ca salicylate.   
     
     
         9 . A method of lubricating a cylinder of a crosshead diesel engine equipped with a scrubber, comprising:
 operating the crosshead diesel engine while supplying the lubricating oil composition as in  claim 1  to the cylinder of the crosshead diesel engine equipped with the scrubber, and   purifying at least a part of gas exhausted from the cylinder in the scrubber.   
     
     
         10 . The method of lubricating the cylinder of the crosshead diesel engine equipped with the scrubber according to  claim 9 ,
 wherein the purifying in the scrubber comprises contacting the gas introduced into the scrubber with water and/or a basic aqueous solution.