DK142060B - Lubricant for diesel engines for maritime use. - Google Patents

Description

OD PRESENTATION 142060

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\ Ra / DENMARK lnt cl · 3 c 10 "1/18" (21) Application No. 6537/75 (22) Filed on 4th Dec. 1973 (23) Race day 4th Dec. 1973 (44) The application presented and p.

the petition published on laugh. SU g · 1 9 OO

DIRECTORATE OF

PATENT AND TRADE MARKET (30) Pnority requested from it

Dec 19 1972, 125511, BE

(71) LABQFINA S.A., 55, rue de la Loi, 1040 Brussels, BE.

(72) Inventor: Georges Souillard, 7a avenue Bel-Air, 1970 Wezembeek-Qppen, BE: Frederic van Quaethoven, 42, avenue de 1'Esplanade, 1970 Wezemf = beek-Oppen, BE.

(74) Plenipotentiary in the proceedings:

Hofman-Bang & Bout engineering firm .___ (54) Marine engine lubricant.

The invention relates to a lubricant for diesel engines for maritime use of the kind specified in the preamble of claim 1.

These marine diesel engines in question are most often low speed engines (maximum 120 rpm) with high power, which can be as large as 4000 horsepower per engine. cylinder.

These engines have two separate lubrication systems: one system for the lower part of the engine (bearings, crossheads, crank heads) and another system for the cylinders.

The separated lubrication of the cylinders works in such a way that the lubricant is injected directly into each cylinder during each cycle. The lubricant is injected radially by means of nozzles around the cylinder. The number of inputs for the lubricant is limited for practical reasons. For example, the distance between two inputs is approx. 35 cm in large engines with cylinders with a bore of up to 100 cm.

In these engines, the growing high pressures existing between the cylinder walls and the piston rings, and also the greater distance between the lubricant inlet openings, cause the injected lubricant to spread only over it with great difficulty. This prevents uniformity and complete lubrication and therefore leads to abnormally high engine wear.

In addition, it is common for diesel engines for maritime use to supply cheap fuel, especially heavy fuel, containing significant amounts of sulfur and ash-forming impurities. These types of fuel directly or indirectly cause a rapid wear of the cylinders by corrosion and wear. It is well known that these fuels in these engines burn during the production of sulfur oxides which, by condensing on the cylinder walls, lead to the formation of corrosive sulfur acid and sulfuric acid. These acids shorten the life of the engine, not only because of their corrosive effect, but also because these acids promote the formation of precipitates (namely, sulfates) that increase the wear of the piston rings and of the cylinder walls.

It is an object of the invention to provide a marine engine lubricant of the kind set forth in the preamble of claim 1 which meets specific requirements and exhibits special properties in connection with such diesel engines, wherein this lubricant is also to form a continuous and homogeneous film. even between the lubricant entry openings, protect the metallic surfaces from corrosion and erosion and reduce wear.

The lubricant according to the invention is characterized by the characterizing part of claim 1.

The base mineral oil used in the lubricant of the invention has a Saybolt viscosity site which is usually between 50 and 1000 SSU at 38 ~ 0. Preferably, my 3 U2060 crude oils are used which give rise to the formation of decomposition products which do not function as bonding agents for the solid particles that result from the combustion of the fuel. Therefore, an mineral based and naphthenic type oil is preferably used. However, the importance of the chemical nature of the additives is greater than the importance of the chemical nature of the base oil and paraffin-based oils can also be used *

To reduce cylinder wear from corrosion, basic additives are incorporated into lubricants. These additives act as neutralizing agents for the corrosive acids formed by the combustion of the fuel. The effectiveness of the lubricant in its anti-corrosive properties depends on the alkalinity index of this lubricant.

The alkalinity index (also referred to as the total base number of TBN) is the equivalent expressed in mg KOH per ml. g lubricant. As a result; thereof, the lubricant should have a TBN as high as possible to neutralize the significant amounts of acidic combustion products. However, comparative trials have shown that there should be a level for this TBN and that a TBN greater than this level does not result in an improvement in the anti-corrosive efficiency of the lubricant. An excessively large amount of basic additive is even detrimental as the amount of precipitates increases. The lubricant according to the invention therefore has an alkalinite one which is between 60 and 70.

The basic additives are selected from the group consisting of superbasic sulfonates or phenates of magnesium or alkaline earth metals, especially superbasic petroleum sulfonates of calcium or barium. For example, a superbasic sulfonate of barium is prepared by reacting a petroleum sulfonic acid with barium methylate and then bubbling CO 2. Thus, these superbasic sulfonates are different from the petroleum sulfonates of calcium, which are generally used as dispersing needles in lubricants for two- and four-stroke engines.

The superbasic sulfonates or phenates have a viscosity index of approx. 250-400. The lubricant according to the invention comprises between 15 and 50% by weight. (calculated in relation to the weight of the entire lubricant) superbasic additive.

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Corrosion wear is reduced with lubricants consisting of a mineral-based oil and a superbasic additive. In order to also reduce the wear caused by non-homogeneous precipitates and lubricant films, it has already been proposed to use lubricants containing butene or isobutene polymers having a viscosity ranging from 30 to 600 SSU at 99 ° C and with a molecular weight not exceeding 1000. The wear of marine engines for maritime use and the formation of precipitates which are detrimental to the life and efficiency of these engines are degraded using these lubricants.

Further experiments have been carried out to meet the recently established requirements which result from the use of high power engines and from the larger sizes of these engines. It has been found that mechanical wear was now more important than wear produced by the combustion products.

Currently, lubricants must meet strict requirements regarding the homogeneity and stability of the lubricating film at the high pressures and high temperatures at which the engines operate.

Surprisingly, engine wear was found to be significantly reduced when incorporating a mixture of polybutene and / or polyisobutenene into the mineral oil.

Comparative experiments have shown that one of the polymers must have a Saybolt viscosity at 99 ° C not higher than 100 SSU and which is generally between 40 and 95 SSU, the other polymer must have a Saybolt viscosity at 99 ° C between 150 and 3000 SSU.

These polymers are polybutenes or polyisobutenes prepared by polymerizing hydrocarbon fractions, which mainly contain alkenes at 4 ° C, in the presence of Friedel-Crafts type catalysts. Since isobutene is the most reactive monomer, a first polymerization produces a product consisting mainly of polyisobutylene. The residual fraction is then polymerized to produce a polymer consisting mainly of polybutene with a small percentage of polyisobutene.

; * '* 5 142060

According to the invention, the lubricant contains both polyisobutenes and polybutenes, whereby these polymers may be hydrogenated at an earlier stage. The most important factor is the viscosity of the polymers. For the sake of brevity, the term poly-C 2 will be used for these polymers.

Prior to the addition of the superbasic additive, the lubricant of the invention comprises between 50 and 90% by weight. of mineral-based oil, as defined above, and between 50 and 10% by weight. of a poly-C1 mixture, in a preferred embodiment of the lubricant of the invention, between 80 and 65% by weight. mineral oil and between 20 and 35% of a mixture of poly-C

Comparative experiments have shown that by adding a mixture of poly-C 2 to a mineral-based oil, mixtures which are particularly suitable as lubricants for diesel engines for maritime use are obtained, although these poly-C 2 are relatively low polymer; molecular weight. In fact, it is well known in the art that lubricating oils generally contain oils on a mineral basis and high molecular weight poly-C 5000, or mixtures of poly-C 2 and alkene copolymers. However, for high temperature lubrication with continuous introduction of the lubricant, such as for example in diesel engines, it has been proposed to use blends containing a base oil and a mixture, the majority of which consists of poly-C ca. Of which less than half consists of poly-C 2 with an average molecular weight of approx. 150,000. The main purpose of these mixtures containing high molecular weight polymers is to avoid excessive variations in viscosity as a function of temperature and to reduce the formation of carbon precipitates at high temperatures.

In modern diesel engines, high temperature efficiency is only one of the requirements and the lubricating oils listed above are not satisfactory. The lubricant must form a continuous and homogeneous film, spreadability, oily nature, mechanical stability and evaporation rate are other important criteria.

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By using "poly-C" mixtures, as defined above, which have a relatively low molecular weight, these requirements are met.

The invention will be illustrated by the following examples.

The properties of the lubricants described in these examples have been evaluated using these blends for lubrication of a marine engine BOLNES 5DNL. This engine is a two-stroke engine with three cylinders. The cylinder diameter is 190 mm and the piston stroke length is 350 mm. Such an engine with pre-compression has an output of 350 horsepower at 500 rpm.

Lubrication of the pistons and of the bearings is carried out by a separate supply for each cylinder by means of individual pumps and oil tanks, so that the oils for the three cylinders can be compared during the tests. Each cylinder has two opposite inlets for lubrication.

The bushes and other auxiliaries are lubricated by the oil in the crankcase, this oil also being used to cool the interior of the pistons.

To evaluate the properties of the lubricants, the weight loss of each ring is checked by weighing the rings before and after each sample. In addition, the purity of the engine after each test has been checked in accordance with the CECM-02-T-70 method (European Coordination Council for the development of performance tests for engine lubricants and fuels). According to this method, the engine for mechanical and chemical breakdown and precipitation is investigated. The grade is based on a grade scale, where 100 means an absolutely clean surface.

EXAMPLE 1

A lubricant was prepared by mixing; 70 parts by weight of an oil on a naphthenic basis with a viscosity of 185 centistokes at 38 ° C.

24 parts by weight of polybutene with an average molecular weight of 610 (Saybolt viscosity: 259 SSU at 99 ° C).

6 parts by weight of polybutene with an average molecular weight of 420 (Saybolt viscosity: 64 SSU at 99 ° C).

To this mixture were added 25 parts by weight of superbasic calcium sulfonate (LUBRIZOL 56) with an alkalinity index of 285.

The lubricating mixture had an alkalinity index or TBN of 62.

This mixture, referred to as "Mixture A", was tested in the previously mentioned diesel engine.

By way of comparison, it can be stated that a similar mixture was prepared, but using 30 parts of polybutene having a molecular weight of 400, instead of the mixture of polybutene.

This mixture is called "mixture B".

The properties of these blends have been compared with the properties of a commercial lubricating oil or reference oil.

The weight loss associated with this oil is assumed to be 100 and the weight loss associated with blends A and B is given as relative loss when compared to this index of 100.

The results were as follows: 8 142060

Character Weight Loss

Reference oil 78.8 100

Mixture A 91 77

Mixture B 70 71

It can be seen from this that the weight loss resulting from wear is significantly reduced when using mixture A or the mixture according to the invention, and in addition, the grade is high. A high grade means a very low corrosion or precipitation formation.

The blend B containing only one type of poly-C 2 is also very valuable in terms of weight loss, but this blend is less advantageous as the grade is lower. EXAMPLE 2

A mixture of the same kind as mixture A of Example 1 was prepared, using 15 parts by weight equal parts of polybutene and polyisobutene having an average molecular weight of 1290 (Saybolt viscosity: 3000 at 99 ° C) and 15 parts by weight of polybutene with an average molecular weight of 420 (Saybolt viscosity: 64 at 99 ° C),

The results were as follows:

Grade: 81 Weight loss: 95 *.

EXAMPLE 3

A lubricant based on: 65 parts by weight of oil on mineral basis and having a viscosity of 192 centistokes at 38 ° 0, 9 parts by weight of hydrogenated polybutene having an average molecular weight of 925 and a Saybolt viscosity of 1008 SSU at 99 ° C was prepared. , 15 parts by weight of hydrogenated polybutene with an average molecular weight of 635 and a Saybolt viscosity of 255 SSU at 99 ° C.

This mixture was divided into three parts and supep <basic magnesium sulfonate was added to each part so that the alkalinity indices were 50, 65 and 85 respectively.

The properties of the three mixtures were as follows:

Character _____ Υ®βϋ £ Ϊ2

Mixture with alkalinity index 50 79 93

Mixture with alkalinity index 65 92 72

Mixture with,.

alkalinity index 85 74 84