Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method and system for modifying a used hydrocarbon fluid to create a
cylinder oil.
FIELD OF THE INVENTION
The invention relates to a method of creating an all-loss lubricant. Further,
the invention relates to a system for creating an all-loss lubricant.
BACKGROUND OF THE INVENTION
Two-stroke crosshead engines used in marine or stationary applications are
equipped with two separate lubricating oil systems. One lubricating system
comprises so-called system oil 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) that normally is used
for
lubrication of the engine's cylinders, piston rings and piston skirt.
In typical two-stroke crosshead engines, the cylinder oil is spent
continuously
by each turn of the engine whereas the system oil in principle is not spent
(except by smaller unintentional leakages). The lubrication system
comprising the cylinder oil is also often referred to as an "all-loss"
lubrication
system as the oil is spent. The use of and various types of both system oil(s)
and cylinder oil(s) is very well known in the art.
The cylinder oil typically contains certain additives that function to reduce,
minimize or neutralise the acid level of the cylinder system.
Typical cylinder oils usually have an SAE (Society of Automotive
Engineering) viscosity equivalent to about 50 and normally have a total base
number (TBN) of about 40 to 70 for the neutralisation of acid products
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produced during the combustion process. Typical system oils usually have
an SAE viscosity of about 30 with a relatively low TBN content, typically
below 10. These exemplary values may vary dependent on the actual
application and the specific design of the systems that the oils are used in.
In recent two-stroke cross-head engine designs involving electronic and/or
hydraulic control and/or activation of valves, etc., the minimum performance
requirements of the system oil has been substantially increased compared to
earlier design using traditional mechanical control/activation.
In four-stroke, trunk piston (diesel) engines, however, typically use only a
single oil type for lubrication and cooling. Such engines are used as
secondary/auxiliary or propulsion engines on ships, or in stationary power
generation or liquid/gas transmission applications. Such used oils typically
have a SAE viscosity of about 30 or 40. While the system oil of two-stroke
cross-head engines typically remains within its specified performance limits
for an extended period of time, trunk piston engine oils are constantly
affected by exposure to the combustion process. However, due to the
inherent design of two-stroke cross-head engines, spent cylinder lubricants
invariably leaks past the piston rod stuffing box contaminating the system
oil.
Thus, the useful properties of both trunk piston engine and system oil
degenerate over time and finally the oils will have to be either replenished
or
completely changed. Similarly, other lubricants used on-board vessels or at
stationary sites, such as hydraulic fluids, gear oils, turbine oils, heavy
duty
diesel oils, system oils, trunk piston engine oils, compressor oils and the
like,
do deteriorate over time, due to e.g. contamination, oxidation, hydrolysis
etc.
and therefore have to be replenished or changed at certain intervals.
The performance level of lubricants is typically measured periodically and
may not go beyond certain limits if the oiled component's condition should
not be jeopardized. An important cause of performance loss is caused by
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particle contamination. These particles include combustion by-products and
wear components, which can be partially removed by oil separators.
However, in the case of two-stroke cross-head engines, one of the sources of
contamination is spent cylinder oil leakage past the stuffing box causing both
the viscosity and base number of the system oil to increase over time, a
process that cannot be reversed by separators.
A diesel engine's frictional loss is mainly of a viscose character. An
increase
in the viscosity of the system oil will therefore result in a diminished
efficiency, increased fuel consumption and increased emissions.
In order to manufacture cylinder oil, prior art methods and systems typically
blend suited base oils and suited additives and/or an additive package to
obtain a fully formulated cylinder lubricant. This is typically done at a
dedicated lubricant blend plant and the resulting cylinder lubricant has to
the
delivered to a ship or an off-shore plant for use in engines.
Apart from the mentioned inevitable mixing of cylinder oil and system oil
prior
art methods and systems do not otherwise mix these types of oils. Further,
some prior art methods/systems also suggest a variation in lubricant flow rate
or properties in response to actual engine conditions, cf. e.g. US 6,779,505.
However, such methods and systems do not address the deterioration of oils
due to contamination or other processes and the potential to re-use these
used oils as cylinder oil.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of creating a
cylinder oil (and a corresponding system) that solves the above-mentioned
(and other) shortcomings of prior art. A further object is to provide this in
a
cost-effective and simplified way.
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A further object of the present invention is to enable improved performance of
non-total loss lubricants over time and thus a more efficient use of both non-
total loss lubricants and cylinder oil.
These objects, among others, are achieved by a method of (and
corresponding system) creating a cylinder oil, the method comprising
modification of at least one initial fluid by determining the TBN(s) of the at
least one initial fluid, determining a desired TBN of a cylinder oil and
adjusting the TBN(s) of the at least one initial fluid accordingly by blending
the at least one initial fluid with suited additive(s).
In this way, a method for modifying an initial fluid to create cylinder oil by
adjusting solely TBN is obtained.
This provides significant economical benefits since lubricants that otherwise
would have to be disposed of can be re-used as a total-loss cylinder
lubricant. Furthermore, cylinder oil does not have to be purchased. The
oil(s) used to blend the cylinder oil is/are of more consistent quality as it
is
replenished (contrary to the traditional practice) which reduces machinery
wear, etc. Thus, the replenishment of the initial fluid(s) provides enhanced
and consistent performance of the initial fluids resulting in greatly reduced
component wear and equipment lifecycle cost. Even further, a more
environmentally friendly method/system is provided since waste, in the form
of spent oil(s) that is discarded after prolonged use, is reduced as it is
converted into cylinder oil.
Preferably, at least one of the initial fluids are at least partially used
oil(s).
Hereby, a fully formulated cylinder lubricant is obtained by modifying TBN of
this used initial fluid(s).
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In a preferred embodiment, the suited additive(s) comprise at least one base.
In a further preferred embodiment, the at least one base comprises
1. basic salts of alkaline or earth alkaline elements, and/or
5 2. detergents and/or
3. dispersants.
The alkaline / earth alkaline elements may be e.g. K, Na, Ca, Ba, Mg or the
like. The basic salts may belong to the inorganic chemical families of e.g.
oxides, hydroxides, carbonates, sulfates or the like. The detergents may
belong to the organic chemical families of e.g. sulfonates, salicylates,
phenates, sulfophenates, Mannich-bases and the like. The dispersants may
belong to the organic chemical families of succinimides or the like.
In a preferred embodiment, the cylinder oil is used in reciprocating internal
combustion engines used in marine or stationary applications. -
In yet another embodiment, the reciprocating internal combustion engines
are two-stroke crosshead engines.
Preferably, the method and embodiments thereof according to the present
invention is used offshore, on-site or in a land based plant.
Preferably, the cylinder oil is created with a TBN in response to fuel oil
characteristics and/or actual engine operating requirements.
In another preferred embodiment, the TBN of the cylinder oil is chosen based
upon sulphur-content of the fuel oil.
Preferably, the initial fluid is a hydrocarbon fluid. In one embodiment, the
hydrocarbon fluid is a lubricant.
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In a preferred embodiment, the lubricant is a used lubricant, i.e. a lubricant
that has at least been partially used elsewhere.
Preferably, the used lubricant is selected from a group of lubricants, such as
hydraulic fluids, gear oils, system oils, trunk piston engine oils, turbine
oils,
heavy duty diesel oils, compressor oils and the like.
In a preferred embodiment, the created cylinder oil is based on two-stroke
engine system oil that continuously, near-continuously or intermittently is
tapped from an existing system and where the system oil is replenished.
In an alternative preferred embodiment, the created cylinder oil is based on a
mixture of lubricants that continuously, near-continuously or intermittently
are
tapped from an existing system and where the lubricants are replenished.
The oils used as initial fluids may e.g. be used or could alternatively be non-
used, i.e. straight from any fresh lubricant storage tank or the like.
In another embodiment, the method further comprises the step of using
suited instrumentation in order to control the quality of the finished
lubricant.
The present invention also relates to a system corresponding to and having
the same advantages as the method of the present invention. More
specifically, the present invention also relates to a system for providing a
cylinder oil, the system comprising: an apparatus for modifying at least one
initial fluid by determining the TBN(s) of the at least one initial fluid,
determining a desired TBN of a cylinder oil and adjusting the TBN(s) of the at
least one initial fluid accordingly by blending the at least one initial fluid
with
suited additive(s).
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Advantageous embodiments of the system according to the present invention
are defined in the sub-claims and described in detail in the following. The
embodiments of the system correspond to the embodiments of the method
and have the same advantages for the same reasons.
BRIEF DESCRIPTION OF THE DRAWINGS
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 shows a schematic block diagram of one embodiment according to
the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 shows a schematic block diagram of one embodiment according to
the present invention. Shown are an all-loss cylinder lubricant supply
comprising cylinder oil (102), base additive(s) (103) and a system oil loop
comprising at least one initial fluid (101). Further shown is a two-stroke
crosshead engine (100), a waste tank (106), a fresh system oil tank (105), a
separator (107) and a blending apparatus (104) for carrying out the present
invention.
According to the present invention the cylinder oil is created by modification
of at least one initial fluid (101) by determining the TBN(s) of the at least
one
initial fluid, determining a desired TBN of a cylinder oil (102) and adjusting
the TBN(s) of the at least one initial fluid (101) accordingly by blending the
at
least one initial fluid (101) with suited additive(s) (103). This is
preferably
done by the blending apparatus (104). Preferably, the at least one initial
fluid
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are at least partially used oil(s). Hereby, a fully formulated cylinder
lubricant
is obtained by modifying TBN of spent oil.
Adjusting the TBN preferably comprises adjusting at least one additive level
or adding one or more additives, where the additives comprise at least one
base comprising basic salts of alkaline or earth alkaline elements, and/or
detergents and/or dispersants.
The alkaline / earth alkaline elements may be e.g. K, Na, Ca, Ba, Mg or the
like. The basic salts may belong to the inorganic chemical families of e.g.
oxides, hydroxides, carbonates, sulfates or the like. The detergents may
belong to the organic chemical families of e.g. sulfonates, salicylates,
phenates, sulfophenates, Mannich-bases and the like. The dispersants may
belong to the organic chemical families of succinimides or the like.
As mentioned, the cylinder oil may be used in reciprocating internal
combustion engines (e.g. two-stroke crosshead engines) used in marine or
stationary applications. The creation of a cylinder oil is due to its
simplicity
and the normal availability of the required initial fluid and the additives
very
suitable for offshore or on-site applications.
The creation of the cylinder oil may also take additional aspects into
consideration such as actual engine requirements and sulphur content of the
fuel.
The used initial fluid may e.g. be hydraulic fluids, gear oils, system oils,
trunk
piston engine oils, turbine oils, heavy duty diesel oils, compressor oils and
the like.
Preferably, the initial fluid is system oil and the total-loss lubricant is
cylinder
oil.
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In one embodiment, the created cylinder oil is based on two-stroke engine
system oil that continuously, near-continuously or intermittently is tapped
from an existing system and where the system oil is replenished.
Alternatively, the created cylinder oil is based on a mixture of oils that
continuously, near-continuously or intermittently are tapped from an existing
system and where the oils are replenished.
The oils may e.g. be used or could alternatively be non-used, i.e. straight
from any fresh lubricant storage tank or the like.
A significant advantage of the present invention is that the main engine(s)
only has to be supplied with fully-formulated, fresh system oil. The system
oil
is then used for its traditional purpose and some of the system oil is blended
with additives adjusting the TBN making it suitable for cylinder oil according
to the present invention. This increases the availability of the needed oil
geographically and increases competition between supplies of oil since all
presently known two-stroke system oils are usable as initial oil for the
cylinder oil by using the present invention. Further, since, where applicable,
other initial fluids, such as but not limited to used hydraulic, gear, trunk
piston
engine or compressor oils may be included in the process of creating cylinder
oil procurement cost will be considerably reduced .
Further, since some of initial fluids are now re-used in the manufacture of
cylinder oil (as opposed to their traditional use) they will have to be
replenished whereby the problem of gradual deterioration is minimised or
avoided.
In a preferred embodiment, a continuous, near-continuous or intermittently
tapping of the system oil from a two-stroke main engine and/or any other
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suited initial fluid is proposed to use these initial fluids as a basis for
the
creation of cylinder oil according to the present invention.
The additive(s) or additive package used by the modifier may serve several
5 purposes but will normally always be used for adjusting the oils TBN. The
process may also be used to provide flexible TBN levels as required by the
actual fuel oil properties and engine operating parameters.
The creation of cylinder oil/cylinder oil according to the present invention
is
10 due to its simplicity very well suited for on-site creation, e.g. aboard a
ship /
vessel, off-shore equipment, stationary plants, etc.
In the claims, any reference signs placed between parentheses shall not be
constructed as limiting the claim. The word "comprising" does not exclude
the 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.
