Patent Description:
Internal combustion engines are widely used as prime movers and other power systems in marine vessels. In order to optimize the operation of internal combustion engines i. in a point of view of emissions, the engines are typically controlled by an electronic control system by means of which the operation may be controlled such that various control values can have an effect on the overall operation of the engines.

In marine vessels the use of so called dual fuel engines operated mainly with gaseous fuel are widely recognized as an environmentally friendly solution. Environmental issues become more and more important and in the operation of power system of marine vessel should be operated accordingly.

Internal combustion engines in general may be provided with exhaust gas emission abatement system external to the engine, in order to meet the requirements set for the emissions. Although the usage of such abatement systems are beneficial in terms of exhaust gas emission level, often the usage of such abatement system involves using additional resources which may have an effect on the engine efficiency and/or incur additional costs.

There are areas or regions in the world where special or different emission regulations are applied and the vessels operation within such region must meet the regulations.

<CIT> and <CIT> both disclose systems where the operation mode or the emission control of an internal combustion engine is adjusted based on information relating to the geographic region. The emissions from power systems, such as propulsion engines and auxiliary engines, in marine vessels have a strong relation to the manner of operating them. Therefore, there is a need to make sure that the power systems operate according to set requirements.

An object of the invention is also to provide a supervising arrangement for a dual fuel internal combustion engine in a marine vessel by means of which the engine is operated in environmentally secure manner.

Objects of the invention can be met substantially as is disclosed in the independent claim and in the other claims describing more details of different embodiments of the invention.

A supervising arrangement for a power system in a marine vessel comprises a control unit adapted to control the power system to operate with at least two operational modes, the supervising arrangement comprising.

the processing unit is arranged to initiate and maintain a data logging operation to record at predetermined interval at least.

and the input unit is further arranged to save the recorded items in a non-volatile memory media which can be written once and read arbitrarily many times, and to set at least one operational restriction to the dual fuel internal combustion engine comprising restricting the operation of the engine in the diesel mode during the intensified supervision operation, and in case an emergency situation is detected arranged to cancel the command to the control unit of the dual fuel internal combustion engine to cancel the at least one operational restriction set to the dual fuel internal combustion engine, and granting full operability in the diesel mode at nominal power for a predetermined time of ≤ <NUM> hours, enabling a safe limp home operation of the vessel, and after the period of time granting operation in the diesel mode at the power less than the nominal power of the engine.

According to an embodiment of the invention the processing unit comprises instruction to record of the using a predetermined time interval and the storing the recorded items in the non-volatile memory media by defining an average value of a number of sequential recorded values.

According to an embodiment of the invention the processing unit comprises further instructions to command to the control unit of the dual fuel internal combustion engine to change over to a restricted mode operation.

According to an embodiment of the invention the dual fuel internal combustion engine comprises an exhaust gas emission abatement system and the processing unit comprises further instructions to preventing switching of the abatement system off.

According to an embodiment of the invention the dual fuel internal combustion engine is a gas engine and processing unit comprises instructions to allow diesel mode operation only in emergency circumstances.

According to an embodiment of the invention the processing unit comprises instructions enabling the switch off the restriction of gas mode only, and operating the engine in liquid fuel mode.

By means of the invention it is possible to constantly monitor and record the engine operation mode. This provides the possibility to verify compliancy of the engine with the regulations during lifetime.

In the embodiment of dual fuel engine the full operability may be granted in also diesel mode or liquid fuel mode in case of emergency enabling a safe limp home operation.

Operation of the engine comprises a step of cancelling the least one operational restriction to the power system in case of an emergency situation. Additionally the information of such cancelling is advantageously subjected to the data logging operation i.e. the event of cancelling the operational restriction is saved in the memory media. This provides an option to continue using the current operational mode without the restriction if that is not possible for some reason to be defined by an officer person being is responsible of the vessel.

Operation of the engine comprises a step of monitoring a status of safety of the vessel and in case a situation of the vessel where the vessel and/or its passengers and/or the crew are/is in imminent danger, or a special situation ruled by the officer in charge of the vessel to be an emergency situation, or a situation where the actual emergency is only about to take place is detected, the emergency detection is declared confirmative.

By means of the invention it is possible to verify that the power system is operating and has been operated using certain operational modes which comply for example with specific rules assigned to a certain geographical area. According to an embodiment of the invention the duration of each used operational mode is recorded separately.

Operation of the engine comprises a step of allowing cancelling the setting of the at least one operational restriction during a limited predetermined period of time and after the period of time has lapsed the at least one operational restriction to the power system is reset.

In the operation of the engine the predetermined interval may be set to be different for recording and saving the item in the memory media, whereas the saved values are average values of unsaved recoded values. The recording interval may be <NUM>-<NUM> seconds and the saving interval may be <NUM>-<NUM> times the recording interval.

The power system is operable with at least two alternative operational modes, which may be referred to as the first operational mode and the second operational mode. The operational modes result in exhaust gas emissions at different levels, types or categories. The actual operational modes which the power system may be set to operate with may be categorized into one of the classes of an accepted operational mode and a non-accepted operational mode. The power system may also include an external exhaust gas emission abatement system in order to meet the requirements set for the emissions.

It should be noted that here the terms "accepted" and "non-accepted" are related to certain location. The operational modes may be categorized for example such that the power system is operable using means belonging to the non-accepted operational mode which results in greater exhaust gas emission level than the accepted operational mode. Respectively the power system is operable using means belonging to the accepted operational mode which results in less exhaust gas emission level than the non-accepted operational mode,.

The emission level, type and/or category which is/are used in definition of the accepted operational mode and the second operational mode may comprises one or more of the following: NOx, SOx, CO<NUM>, particulate matter and noise emission.

There are various possible operational steps and/or procedures relating to operation of, as well as technical devices applicable to an internal combustion engine, known in the art as such, each of which have an effect on the emission level and/or type of the emission and may therefore be a subject to a predetermined operational restriction. Each of these may be categorized into one group of the first and the second operational mode. The actual case to which one of the groups each operation step and/or procedure and/or technical device belong is determined directly or indirectly by the restriction map according to the present invention.

The operational steps and/or procedures relating to the method operating the engine, as well as technical devices applicable to an internal combustion engine may be selection between at least two different fuel, using of exhaust gas emission abatement device, such as catalytic or non-catalytic exhaust gas reduction system, exhaust gas recycling, water injection into the combustion air and/combustion process, etc..

Accordingly, when the engine comprises an exhaust gas emission abatement system and the at least one operational restriction may comprise preventing switching of the abatement system off.

The engine is a multi-fuel piston engine it may be operated with gaseous fuel, such as natural gas, i.e. in gas mode representing the first operational mode, and with liquid fuel, such as marine diesel oil or light fuel oil i.e. in liquid fuel mode representing the second operational mode. It should be noted that a diesel mode is a specific form of the liquid fuel mode. Now, in some areas the gas mode may represent the accepted operational mode due to its low emissions and the liquid mode may represent non-accepted operational mode due to its greater emissions.

In case there are specific restrictions assigned to a geographic area those restrictions are verifiably obeyed once the vessel enters into such area. So in addition to making it possible to verify that the power system is operating and has been operated using certain operational modes which comply for example with specific rules assigned to a certain geographical area, the actual operation mode is ruled by detected geographic area and operational restrictions set to the power system according to the restriction information map.

In connection with this application the emergency situation or circumstances may include, in addition to actual emergency situation where the vessel and/or its passengers and/or the crew are/is in imminent danger, a special situation ruled by the officer in charge of the vessel to be an emergency situation, or a situation where the actual emergency is only about to take place unless a counter measure is commenced as soon as possible.

<FIG> depicts schematically a supervising arrangement <NUM> for operating a power system <NUM> in a marine vessel <NUM>. The power system <NUM> is operable with at least two alternative operational modes which result in exhaust gas emissions at different levels or categories. The operational modes may be called also as accepted operational mode and non-accepted operational mode which refers to exhaust gas emission level in respect to local regulations or requirements. The power system is here a dual fuel internal combustion piston engine <NUM>, capable of operated e.g. with gaseous and liquid fuels. For sake of simplicity the term engine may be used instead of dual fuel internal combustion engine.

The engine <NUM> is in connection with a source of a gaseous fuel <NUM>, such as natural gas and a source of liquid fuel <NUM>, such as marine diesel oil (MDO). The engine comprises liquid fuel injectors <NUM> arranged in connection with the cylinders <NUM> of the engine, optionally provided with pre-chambers. The engine comprises also gas admission valves <NUM> arranged in connection with intake channels of the engine. The engine is advantageously turbocharged engine with at least one turbocharger unit <NUM>. The engine may be connected to an electric generator <NUM> to provide power for e.g. propulsion systems of the vessel (not shown). The gas engine according to a preferred embodiment of the invention is arranged to use the MDO liquid fuel source and its fuel introduction system serves also as a backup system.

Even if not shown in the <FIG> the engine, according to an embodiment of the invention is provided with a third fuel source, namely a source of heavy fuel oil (HFO) and injection system adapted to inject heavy fuel oil into the cylinders. The third injection system is normally intended to be used as a back-up system, and the engine being then operated in diesel mode.

The combustion concept of the engine shown in <FIG> allows alternatively a diesel operation mode utilizing single liquid fuel (MDO, HFO) or a gas operation mode utilizing e.g. natural gas as the main fuel. Both of the operational modes utilize advantageously liquid fuel injection with compression ignition, even if e.g. a spark ignition during the gas mode may also be conceivable. In the gas mode the engine is operating with the otto-principle and according to so called lean burn principle. The natural gas is injected in the intake ports and premixed air and fuel is introduced into the cylinder. Ignition is accomplished with a pilot fuel injection of suitable liquid fuel, such as marine diesel oil (MDO). MDO is injected directly into the cylinder or a pre-chamber thereof initiating the combustion. Particularly the lean burn gas mode provides considerably low emission levels.

The engine <NUM> is provided with a control unit <NUM> which is adapted to control the engine <NUM> to alternatively run in the first mode of operation or in the second mode of operation. In the embodiment shown in <FIG>, where the engine is a dual fuel engine, the first mode of operation is gas mode operation and the second mode of operation is diesel mode operation, which result in exhaust gas emission at different levels or magnitudes.

Now, in order to increase the environmental reliability of the power system and the marine vessel, there is the supervising arrangement <NUM> arranged in connection with the engine <NUM>. The supervising arrangement <NUM> comprises as its main component a processing unit <NUM> and location information receiving system <NUM>. The processing unit is adapted to perform operations by means of which the operation of the power system <NUM> i.e. the engine may be effectively verified and also controlled. The location information system <NUM> may be realized by providing a data transmission connection with the vessel's position tracking system.

The processing unit <NUM> is adapted to communicate with the control unit <NUM> of the engine and there is a data transfer communication link <NUM> arranged between the control unit <NUM> and the processing unit <NUM> for that purpose. Facilitated by the communication feature the processing unit <NUM> is adapted to receive measured or otherwise determined status information of the engine's operation via the data transfer communication link <NUM>. Particularly, the processing unit is adapted to receive a specification of currently used operational mode of the power system <NUM>.

The supervising arrangement <NUM> further comprises a location information receiving system <NUM>, which is adapted to acquire constantly or intermittently information of the location of the vessel <NUM>. There is a data transfer communication link <NUM> arranged between the location information receiving system <NUM> and the processing unit <NUM> for that purpose. The location information receiving system <NUM> is based on for example a receiver of the Global Positioning System (GPS) signal, which is an example of a space-based satellite navigation system that provides location information usable for the invention.

The location information receiving system <NUM> is arranged to communicate with the processing unit <NUM> so that the location information is made available to the processing unit. The location information receiving system <NUM>, particularly if being the GPS system, may deliver time stamp information to the processing unit <NUM>, as well.

The processing unit <NUM> comprises a first storage unit <NUM> into which a restriction information map is stored. The restriction information map is arranged to contain information of geographical areas or locations and possible operational restrictions related to the areas or locations and being relevant to the operation of the power unit <NUM> at the areas. As an advantageous embodiment the operational restrictions are exhaust gas related restrictions. So, the restriction relates advantageously to exhaust gas emissions of the power unit <NUM> and may be set for example to an area where only a certain NOx and/or SOx levels in the exhaust gas are permitted.

The restriction information map is formed by assigning geographical areas with one or more predetermined operational restrictions. This may be implemented for example by defining a range of latitude/longitude pair within which range a certain restriction is applied.

The processing unit <NUM> comprises further a second storage unit <NUM>, which comprises a non-volatile memory media. The non-volatile memory media of the second storage unit <NUM> is utilized for purposes which will become apparent later. The first <NUM> and the second <NUM> storage units may physically be the same device having dedicated areas for the different information. According to the invention the second storage unit <NUM> comprises a non-volatile memory media which can be written once and read arbitrarily many times.

The processing unit <NUM> comprises instructions to acquire the location information of the vessel from the location information receiving system <NUM> and make it available for the processing. The processing unit comprises also instructions to acquire and make available for processing the actual operational mode of the power system <NUM>.

Further, the processing unit comprises instructions to read the restriction information map in the first storage unit <NUM>, and to select the restriction information relevant to the current location of the vessel and compare the location information and the restriction information map. The instructions comprises still further, in case the comparison reveals that the restriction information map includes one or more restrictions assigned to the current location, execution of initiating an intensified supervision operation of the arrangement <NUM>.

For the intensified supervision operation of the arrangement <NUM>, i.e. for the situation where the comparison described above results in an existence of a restriction at the current location, the processing unit comprises instructions to initiate and maintain a data logging operation which comprises instructions to record at predetermined time interval at least.

and storing the recorded items in the non-volatile memory media of the second storage unit <NUM>.

This way the supervising arrangement provides means for increasing the environmental reliability and verifiability of the operation. When the vessel is in the region where exits possible operational restrictions relevant to the operation of the power unit <NUM> the operational status of the engine <NUM> is stored in non-volatile memory media for later inspection and verification of the situation. The non-volatile memory media <NUM> is advantageously set as allowing only writing and reading the information but preventing any modification of stored information.

The predetermined interval is advantageously not more than <NUM> seconds depending to the actual case. Naturally, if it is allowed to have less accurate supervision, it is possible to decrease the rate. According to an embodiment of the invention the recording of the items takes place using interval not more <NUM> seconds and the saving the recorded items in the non-volatile memory media is performed by defining an average value of a number of sequential recorded values. The recording average values may be performed once in a minute.

The processing unit comprises according to an embodiment a computer device and the instructions relating to the processing unit are according to the embodiment in a form of computer executable program. As is depicted by the reference number <NUM>' the processing unit and the control unit <NUM> may be arranged into a one computer device or they may be separate devices as is exemplary shown in <FIG>.

According to an the invention the processing unit <NUM> comprises instructions for the intensified supervision operation, i.e. for the situation where the comparison described above results in an positive indication of a restriction at the current location, further instructions to command to the control unit <NUM> of the power system <NUM> to change into a restricted mode operation. This may be conceived as more advanced mode of intensified supervision operation. The restricted mode operation is realised by the control unit <NUM> based on the restricted mode operation instructions which are stored in the processing unit <NUM>.

In order to run the restricted mode operation the processing unit <NUM> comprises firstly an instruction to designate the gas mode as only available normal running mode. This way, when the vessel <NUM> is in the area having operational restrictions relating to gaseous emission levels, during normal operation only the gas mode operation of the engine <NUM> is allowed by the supervising arrangement <NUM>, and by means of the arrangement <NUM> the at least one operational restriction subjected to the engine <NUM> comprises restricting the operation in the diesel mode.

Additionally the processing unit comprises instructions to allow diesel mode operation only in emergency circumstances. This is despite the fact that the gas mode has been designated as the only available normal running mode in the restricted mode. These instructions are transmitted by the processing unit <NUM> to the control unit <NUM>. The instructions for emergency circumstances include enabling the switch off the restriction of gas mode only, in the event that a gas related failure condition is present, and the load reduction of the engine is not allowed. Such a reduction of load could some cases possibly remove the cause for the failure condition. According to a special embodiment of the invention the instructions for emergency circumstances include also instruction to operate the engine <NUM> by using the MDO for both the pilot fuel and main fuel and preventing the operation of the engine with HFO fuel, in case the engine is provided with diesel mode fuel injection system adapted to utilize HFO. Thus, the restricting of operation in the diesel mode comprises granting full operability in diesel mode in case of emergency only during a predetermined time enabling a safe limp home operation. Also, and particularly during the emergency circumstances the data logging operation is maintained which comprises instructions to record at predetermined interval at least the current location information of the vessel, a specification of used operational mode of the power system <NUM> at the location and storing the recorded items in the non-volatile memory media of the second storage unit <NUM>.

The instructions for emergency circumstances include also setting a time period for nominal power during a predetermined period of time, which may be for example <NUM> -<NUM> hours and allowing usage of only limited power, less than the nominal engine power after the time period. And still, instruction relating to intensified supervision operation are applied during the emergency circumstances. Thus, the restricting of operation in the diesel mode may comprise granting <NUM>-<NUM> hours operation at nominal power and after that less than nominal power.

With the reference to <FIG> the operation of the supervising arrangement <NUM> is explained in connection with a dual fuel internal combustion engine <NUM> is a marine vessel <NUM>.

Firstly the restriction information map must be provided for disposal of the arrangement <NUM>. This is accomplished by assigning geographical areas with one of more predetermined operational restriction set for the power system <NUM>. It is clear that this step is typically practised only according to need e.g. when the information is changed. The restriction information map is advantageously stored in the first storage unit <NUM>. When practising the method the location information is acquired by the read by the location information receiving system <NUM> for use in a comparing procedure. Prior to the comparing procedure the restriction information map is read to obtain the restriction information relevant to the recently acquired current location of the vessel i.e. if there is any relevant restriction set to the operation of the engine. Particularly the restrictions related to exhaust gas emissions of the engine such as maximum allowed emissions into the atmosphere. Now, in the comparing procedure the location information and the restriction information map, and in case the restriction information map includes one or more restrictions assigned to the current location, the intensified supervision operation of the power system is initiated.

During the intensified supervision operation the data logging operation is initiated and maintained which comprises recording at predetermined interval at least the current location information of the vessel <NUM>, and a specification of used operational mode of the power system at the specific location as well as saving the recorded items in the memory media of the first storage unit <NUM>. Preferably also the duration of the each used operational mode is recorded as well. It is also conceivable to transmit the recorded items to a land-based third storage unit.

In order to provide even more advanced method at least one operational restriction to the power system may be set during the intensified supervision operation. This way in addition to saving the above mention item into a non-volatile memory medium the operation of the engine is restricted to be selected from a group of accepted operational modes.

In the <FIG> there is shown schematically a supervising arrangement <NUM> for operating an internal combustion engine unit <NUM> in a marine vessel <NUM>. The engine <NUM> is operable with at least two alternative operational modes which result in exhaust gas emission at different levels, the modes may be called also as accepted operational mode and non-accepted operational mode. In this embodiment the operational modes accomplished by following setup. Even if a piston engine is shown in the figure the engine may also be for example a gas turbine unit.

In addition to what is disclosed in <FIG> the engine unit in <FIG> comprises a selective catalytic reduction system SCR <NUM> in connection with its exhaust gas channel <NUM> of the engine <NUM>. The selective catalytic reduction system comprises a catalyst unit <NUM>, and an optional reductant introduction unit <NUM> and a by-pass duct <NUM> for by-passing the selective catalytic reduction system <NUM>. The by-pass duct <NUM> is provided with a valve device <NUM> by mean of which the gas flow may be controlled between the selective catalytic reduction system <NUM> and the by-pass duct <NUM>.

The valve device and/or the reductant introduction unit <NUM> are connected to the control unit <NUM> of the engine. The connection may be alternatively or additionally to the processing unit <NUM> which is not shown here. In this embodiment the power system <NUM> is operable with at least two alternative operational modes which result in exhaust gas emission at different levels, the modes may be called also as accepted operational mode and non-accepted operational mode. One of the operational modes comprises setting the valve unit <NUM> such that leading the exhaust gases to the catalytic reduction system <NUM> takes place and introducing reactant into the exhaust gas prior to its introduction in the catalyst unit <NUM>. Accordingly in this embodiment the processing unit <NUM> comprises instruction to initiate the operation by the control unit <NUM>. Another operational mode is setting the valve unit <NUM> such that leading the exhaust gases to by-pass duct <NUM> takes place. Accordingly in this embodiment the processing unit <NUM> comprises instruction to initiate the operation by the control unit <NUM>, respectively.

Additionally the engine <NUM> may a dual fuel engine, so its operation and the supervising arrangement <NUM> described in connection with the <FIG> applies also to the embodiment of <FIG>. Thus, in this embodiment the at least one operational restriction comprises preventing the switching the selective catalytic reduction system off.

In <FIG> there is show an exemplary chart describing the present invention implemented in a dual fuel internal combustion piston engine. The vertical axis represent relative load of the engine <NUM> and the horizontal axis represent time. Some aspects about the restricted mode operation and instructions for dual fuel engine <NUM> are described in the following with the reference to <FIG> in more detailed manner. The engine is operated making use of an accepted mode of operation, for example operating in the gas mode (<FIG>) or using SCR system (<FIG>. ), during which nominal power is available for use. This situation is depicted with solid line <NUM>. In case of an emergency situation (e.g. malfunction in the gas fuel system) the available power is decreased as in depicted by <NUM>.

According to an embodiment of the invention the instructions for emergency circumstances include granting full nominal power operability in diesel mode as is depicted by reference <NUM>. Now, the engine <NUM> may be operated by using the MDO for both the pilot fuel and main fuel. But as is shown by Δt in the horizontal axis, the instructions for emergency circumstances include also setting a time period for full power to a predetermined time. The time is advantageous <NUM> hours, at most. After the predetermined time has lapsed only a limited power is allowed as is depicted by reference <NUM>. Thus, the restricting of operation in the diesel mode may comprise granting a predetermined number of hours operation at nominal power and after that less than the nominal power. The illustration of <FIG> can be applied to various exhaust gas emission abatement system external or internal to the engine and operational steps and/or procedures relating to the method operating the engine, as well as technical devices applicable to an internal combustion engine such as selection between at least two different fuel, using of exhaust gas emission abatement device, such as catalytic or non-catalytic exhaust gas reduction system, internal and/or external exhaust gas recycling, water injection into the combustion air and/combustion process, etc..

According to an embodiment of the invention a resetting the emergency circumstances s only possible after <NUM> minutes of operation free of fault conditions in the gas mode or accepted mode, generally.

Claim 1:
A supervising arrangement (<NUM>) in a dual fuel internal combustion engine (<NUM>) in a marine vessel, which arrangement comprises a control unit (<NUM>) adapted to control the dual fuel internal combustion engine, the supervising arrangement comprising
- a location information receiving system adapted to acquire location information of the vessel
- a processing unit, which is arranged to communicate with the location information receiving system and the control unit
characterized in that the supervising arrangement comprising
- an input unit for acquiring the actual operational mode of the dual fuel internal combustion engine from the control unit, the input unit is arranged
- to read a restriction information map in which geographical areas are assigned with one or more predetermined operational restrictions, and
- to obtain the restriction information relevant to the current location of the vessel, and
- to compare the location information and the restriction information map, and in case the restriction information map includes one or more restrictions assigned to the current location, to initiate an intensified supervision operation of the dual fuel internal combustion engine, during which the processing unit is arranged to initiate and maintain a data logging operation to record at predetermined interval at least
- current location information of the vessel, and
- a specification of used operational mode of the dual fuel internal combustion engine at the location,
and the input unit is further arranged to save the recorded items in a non-volatile memory media which can be written once and read arbitrarily many times, to set at least one operational restriction to the dual fuel internal combustion engine (<NUM>) during the intensified supervision operation and in case an emergency situation is detected arranged to command the control unit (<NUM>) of the dual fuel internal combustion engine (<NUM>) to cancel the at least one operational restriction set to the dual fuel internal combustion engine (<NUM>) and grant full operability in a non-accepted operational mode at nominal power for a predetermined time of ≤ <NUM> hours, enabling a safe limp home operation of the vessel, and after the period of time grant operation in the non-accepted mode, at power less than the nominal power of the engine.