WO2015040269A1

WO2015040269A1 - Arrangement of control system and auxiliaries for lng fuel storage sytem

Info

Publication number: WO2015040269A1
Application number: PCT/FI2013/050911
Authority: WO
Inventors: Fredrik Sundelin; Mikael LALL; Jonatan BYGGMÄSTAR; Mathias Jansson; Sören KARLSSON
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2013-09-20
Filing date: 2013-09-20
Publication date: 2015-03-26
Anticipated expiration: 2016-03-20

Abstract

A fuel storage and delivery system for a gas-fuelled sea-going vessel com- prises a tank room, which is a gas tight space enclosing tank connections and valves associated with them. Within or in immediate association with said tank room there is provided a communications demultiplexer configured to convey multiplexed control information from an external connection and to deliver dedicated control outputs to individual actuators that drive actions within said tank room.

Description

Arrangement of control system and auxiliaries for LNG fuel storage system

TECHNICAL FIELD The invention concerns in general the fuel storage and delivery systems in gas-fuelled sea-going vessels. In particular the invention concerns the way in which the remote control of sensors and actuators is arranged in the fuel storage and delivery system.

BACKGROUND OF THE INVENTION Natural gas, or in general mixtures of hydrocarbons that are volatile enough to make the mixture appear in gaseous form in room temperature, constitutes an advantageous alternative to fuel oil as the fuel of internal combustion engines. In sea-going vessels that use natural gas as fuel, the natural gas is typically stored onboard in liquid form, giving rise to the commonly used acronym LNG (Liquefied Natural Gas). Natural gas can be kept in liquid form by maintaining its temperature below a boiling point, which is approximately -162 degrees centigrade (-260 degrees Fahrenheit). Natural gas can be also stored for use as fuel by keeping it compressed to a sufficiently high pressure, in which case the acronym CNG (Compressed Natural Gas) is used. This description refers mainly to LNG because liquefying is considered more economical than compressing at the time of writing this text.

Fig. 1 illustrates some parts and components of an LNG-fuelled vessel. The engines, of which there can be one, two, or more, are located in the engine room 101 . In this example we assume that there are two LNG-fuelled engines 102 and 103, each with its own fuel input subsystem 104 and 105 respectively. The fuel input subsystem of a typical LNG-fuelled engine is sometimes also referred to as the GVU (Gas Valve Unit), and it may comprise for example a manual shut-off valve, a gas filter, a pressure regulation valve as well as the valves and connections needed for bleeding, blocking, inerting, and venting the gas supply line.

Gas is stored in liquid form in one or more gas tanks 106, which are located either in a tank hold 107 or on open deck. Close to (or even attached to) the tank or tanks 106 is a tank room 108, which is a gastight space that encloses the tank connections and valves associated with them, as well as the evaporators that are used to vaporize the gas. These components are generally referred to in fig. 1 with the reference designator 109. A bunker station 1 10 comprises the connections and valves 1 1 1 that are used to fill the gas tanks 106 with LNG.

The supply 1 12 of a glycol / water mixture for use in the evaporators may also be located in the engine room 101 , as can the supply 1 13 of compressed air and/or hydraulic fluid that serve as the driving medium or media for remotely operated valves and possible other actuators. The bunker station 1 10 may be equipped with a bunker control panel 1 14 for locally controlling the connections and valves 1 1 1 that are used for bunkering.

The control of all remotely operated valves and other actuators, as well as the collection of feedback information from the various units, is concentrated to a device known as the programmable controller 1 15. It has an I/O (input/output) interface 1 16, to which are connected all devices in the other illustrated blocks that need to be controlled electrically, as well as all sensors that produce feedback measurements. The programmable controller 1 15 may be located in a particular space called the switchboard room 1 17, or in some other room that ranks among the machinery spaces of the vessel. The programmable controller 1 15 has a digital connection interface to a control bus 1 18, to which also the human interfaces 1 19 and 120 are connected. The last-mentioned can be located for example in an engine control room 121 and on the bridge 122. A human interface may comprise for example a display and a keyboard, or a touchscreen, or some other means through which a human user can obtain information and give commands.

Other connections to the programmable controller 1 15 exist but are not illustrated in fig. 1 to maintain graphical clarity. These other connections may include for example flow indication signals from ventilation feedback measurements; shutdown commands from fire and gas detection systems; ESD (Emer- gency ShutDown) signals from USD buttons placed at critical locations; and operating power connections from regular and emergency current sources.

The electric connections that convey the voltages and/or currents that drive the actuators, and that also convey the measured feedback back to the programmable controller 1 15, are illustrated with simple lines in fig. 1 , but in practice they may involve a significant amount of cabling. Even if many units such as the equipment in the tank room 108 and the fuel input subsystems 104 and 105 may be pre-assembled by subcontractors and provided to the shipyard, it takes a lot of valuable construction time at the shipyard to draw, connect, tie down, and test all the required connections.

SUMMARY OF THE INVENTION

The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

According to an aspect of a present invention, there is provided a fuel storage and delivery system for a sea-going vessel, which fuel storage and delivery system exhibits a high degree of integration. According to another aspect of the invention there is provided a fuel storage and delivery system that saves assembling time on a shipyard when an LNG-fuelled sea-going vessel is built. According to yet another aspect of the invention there is provided a fuel stor- age and delivery system that enables achieving savings in manufacturing costs. According to a further aspect of the invention there is provided a seagoing vessel that comprises a fuel storage and delivery system of the kind described above.

Advantageous objectives of the invention are achieved by placing a communi- cations demultiplexer within or in immediate association with the tank room.

A fuel storage and delivery system for a sea-going vessel according to the invention is characterized by the features recited in the characterizing part of the independent claim directed to a fuel storage and delivery system.

A sea-going vessel according to the invention is characterized by the features recited in the characterizing part of the independent claim directed to a seagoing vessel. A method for constructing a fuel storage and delivery system according to the invention is characterized by the features recited in the characterizing part of the independent claim directed to a method.

The tank room, or even a larger part of the fuel storage end delivery system together with the LNG tanks and all, can be provided to the construction of a sea-going vessel as a module. When a communications demultiplexer is placed within or in immediate association with the tank room, it becomes possible to replace many of the previously existing connections with a single bus connection or command line. The same bus connection or command line can be used both for conveying commands inwards to the actuators within the fuel storage and delivery system and for conveying inputs from measurement sensors and/or other individual signal sources within the fuel storage and delivery system outwards.

Any addition to the electronic components within the fuel storage and delivery system, such as the addition of a communications demultiplexer, must be weighed against the possible addition in cost, especially if components certified for explosive environments must be used. One alternative is to build a cabinet that is an enclosed space external to but mechanically attached with the tank room, and to place the communications demultiplexer within the cabi- net. By building the access and ventilation arrangements in an appropriate way it can be ensured that the inside of the cabinet never becomes a gas- hazardous space, in which case components certified for regular maritime use are quite sufficient.

The communications demultiplexer can comprise various degrees of built-in in- telligence. In one example the communications demultiplexer may implement in practice all the functions of the programmable controller that was used in prior art solutions, so that the bus connection may even be a general bus connection, which couples the communications demultiplexer to the same control bus to which also the human interfaces are coupled. In another example the communications demultiplexer may be a simple remote I/O interface that does little more than a corresponding part of the I/O interface of a prior art programmable controller, only located in a different place. An intermediate example between those explained above is a limited-functionality programmable controller that operates under the main programmable controller, and has a lo- cal bus connection thereto. The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 illustrates a prior art LNG fuel delivery control architecture, fig .2 illustrates the concept of a solenoid valve cabinet,

fig. 3 illustrates a cabinet-based embodiment of the invention,

fig. 4 illustrates another cabinet-based embodiment of the invention, fig. 5 illustrates parts of a controller that can be used in an embodiment according to fig. 3 or fig. 4,

fig. 6 illustrates a remote I/O based embodiment of the invention, fig. 7 illustrates parts of a remote I/O interface and a corresponding controller,

fig. 8 illustrates an LNG fuel delivery control architecture according to an embodiment of the invention, and

fig. 9 illustrates some connections to and from a tank room.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The classification of spaces on board a sea-going vessel into gas-hazardous areas defines the tank room as zone 1 . One of the consequences is that any occurrence of electric sparks must be strictly prevented, and all components such as solenoids, switches, and electronic circuits that are installed in the tank room must be of a kind certified for use in explosive spaces. To operate actuators inside the tank room, a so-called SVC or solenoid valve cabinet can be used, as illustrated schematically in fig. 2. The concept "solenoid valve" is used in this description for an entity that comprises an electrically operated so- lenoid 201 as well as a solenoid-operated valve 202, which can be for example a pneumatic or hydraulic valve and which is driven by movements of the solenoid 201 .

In the schematic illustration of fig. 2 a number of solenoid valves are placed in an SVC 203, which has a pressurized air input 204 and a number of electric control inputs 205. Depending on the position of the solenoid 201 each solenoid-operated valve 202 either allows or blocks the flow of pressurized air through a corresponding pneumatic connection 206 to a pneumatic actuator 207, which in turn drives an action, for example operates a valve 208 in the tank room that controls the flow of gas in a gas pipe 209.

Fig. 3 illustrates an example of how a communications demultiplexer 301 can be arranged in immediate association with a tank room 302. The general designation "communications demultiplexer" can be used of devices of slightly different nature, as will be explained in more detail below. As a common feature, all communications demultiplexers are configured to convey multiplexed control information from an external connection and to deliver dedicated control outputs to individual actuators that drive actions within the tank room.

The communications demultiplexer 301 is located in a cabinet 303, which is an enclosed space external to but mechanically attached with the tank room 302. The mechanical attachment may be direct, for example so that the cabinet 303 and the tank room 302 share at least one wall, or indirect for example so that they both are parts of a separately built LNG supply assembly, in which an LNG tank, the tank room 302, and the cabinet 303 share a skid base or other common support structure. In the arrangement of fig. 3 the delivery of dedicated control outputs to individual actuators takes place indirectly, by using an SVC 203 of the kind described above in association with fig. 2. The communications demultiplexer 301 produces dedicated control outputs in electric form. The cabinet 303 comprises one or more solenoid valves, which in this case are located in the SVC 203 but which could also be located elsewhere within the cabinet 303, i.e. so that the cabinet 303 would simultaneously fulfill the definition of an SVC. Said one or more solenoid valves are configured to drive actions within the tank room 302 through at least one pneumatic or hydraulic connection 206 from the cabinet 303 to the tank room 302. In the embodiment of fig. 3 the external connection to and from the communications demultiplexer 301 is a general bus connection 304. It couples the communications demultiplexer 301 to a control bus 1 18, to which also human interfaces for monitoring actions within said tank room are to be coupled (see units 1 18, 1 19 and 120 in fig. 1 ). Since the communications demultiplexer 301 in this respect implements all functions that were on the responsibility of the programmable controller 1 15, we may designate it also as the programmable (logic) controller or PLC. In order to emphasize that this PLC only has responsibility of things taking place within or in association with the tank room where LNG is processed, it could be designated as LNG-PLC.

Basically there would be no technical reasons that would prevent the LNG- PLC from taking even all responsibilities of the prior art programmable controller 1 15; in other words, using an LNG-PLC as the communications demultiplexer 301 would represent transferring the prior art programmable controller from the switchboard room to a cabinet 303 mechanically attached with the tank room 302. However, a significant advantage could be at least partly lost, because the prior art programmable controller 1 15 had connections to also other devices than the actuators and sensors within or in association with the tank room. An advantage of the present invention is the limited amount of ca- bling that needs to be installed between the tank room and the other machinery spaces at the shipyard where a new gas-fuelled vessel is built or a vessel is converted to using gaseous fuel. If a full-scale programmable controller such as that designated as 1 15 in fig. 1 is placed within or in immediate association with the tank room, all such cabling needs to be installed anyway that carries signals to and from other parts of the vessel than the LNG storage and delivery system.

Fig. 4 illustrates a slightly different embodiment, where the difference to fig. 3 is in the external connection 401 to and from the communications demultiplexer. In the embodiment of fig. 4 we assume that a programmable (logic) control- ler 403 definitely exists, for example in a switchboard room like in fig. 1 . The external connection 401 of the communications demultiplexer 301 is a dedicated bus connection, which couples the communications demultiplexer to a local bus 402, to which also the programmable controller 403 is coupled. The bus connection between the communications demultiplexer 301 and the pro- grammable controller 403 is "dedicated" in the sense that it does not go further to other devices, or at least is not quite as general and extended as the control bus 1 18 to which the human interfaces are coupled.

In embodiments such as those in figs. 3 and 4 the communications demultiplexer 301 can be a programmable logic controller, an example of which is il- lustrated schematically in fig. 5. It comprises a processor 501 and a memory 502 for storing a program, the execution of which is configured to make the processor 501 convey information between an external connection (bus interface 503) and a number of dedicated control outputs (I/O drivers 504). An I/O communications module 505 may be located between the processor 501 and the I/O drivers 504. An internal power source 506 is also illustrated in fig. 5, with which electric operating power brought to the programmable logic controller is regulated and distributed to the various parts according to need. Depending on whether the bus interface 503 constitutes a general bus interface to a control bus or a dedicated bus interface to a local bus some differences come into play, but since a large variety of bus technologies are known and widely in use, selecting an appropriate bus interface and making it operation in the appropriate way is straightforward to the person skilled in the art.

Above we have mainly mentioned control outputs to individual actuators that drive actions within the tank room. However, both in the embodiments dis- closed so far and also in the other embodiments of the invention at least some of the I/O connections can act, as already their name indicates, as inputs. There may be measurement sensors and/or other signal sources within or in immediate association with the tank room, from which the generated signals need to be communicated outwards. For this purpose the communications demultiplexer is additionally configured to perform as a communications multiplexer, for conveying inputs from individual signal sources into multiplexed outputs to be transmitted through the external connection.

Fig. 6 illustrates a slightly different embodiment, in which the communications demultiplexer 301 is a remote input / output interface. As a difference to a pro- grammable logic controller, a remote input / output interface is fixedly configured to convert multiplexed commands received through the external connection to dedicated control outputs. In order to underline the difference to fig. 4 we use the designation command line 601 to designate the connection between the communications demultiplexer 301 and an external PLC 602, which may again be located for example in a switchboard room or elsewhere in the machinery spaces of the vessel.

In the embodiment of fig. 6 the communications demultiplexer 301 and a number of solenoid valves are located in an SVC 603 inside the tank room. Here we assume that a remote I/O interface consists of relatively simple electronic components, so that the manufacturing costs do not become excessively high even if they had to be certified for use in explosive spaces. If properly certified components are used, even a separate SVC may be dispensed with, so that the communications demultiplexer 301 and the actuators to which its control outputs go are all freely located inside the tank room.

Fig. 7 illustrates schematically an example of how the embodiment of fig. 6 could differ from that of figs. 3 and 4. A remote I/O interface comprises a command line interface 701 , an I/O communications module 702, and a number of individual I/O drivers 703 as well as an internal power source 704. From the command line interface 701 there is a command line connection 601 to a controller 602, which comprises a corresponding command line interface 71 1 , a processor 712, a memory 713, a bus interface 714, and an internal power source 715.

Fig. 8 illustrates an example of an LNG fuel delivery control architecture ac- cording to an embodiment of the invention. In addition to the differences in electric control lines and appliances, there is the significant difference to the prior art arrangement of fig. 1 that the engine-specific fuel input subsystems 804 and 805 are now located in the tank room 808. This placing of the engine- specific fuel input subsystems has been described in more detail in the co- pending patent application number XXXXXXXX of the same applicant, which at the time of writing this description is not yet available to the public. Significant advantages can be achieved in such a solution, for example because the gastight enclosure that the tank room 808 constitutes makes it unnecessary to enclose the fuel input subsystems separately in gastight covers. At the same time the degree of integration of the fuel storage and delivery system - and the consequent savings in construction time at the shipyard - increases, because the engine-specific fuel input subsystems can be brought to the shipyard as a part of the completely sub-assembled tank room. We assume that a control architecture like that illustrated in fig. 8 comprises a switchboard room 1 17 that houses a programmable controller 815, from the I/O interface 816 of which control lines go for example to a glycol / water supply 1 12 and a pneumatic / hydraulic supply 1 12 in the engine room 101 . How- ever, the command line to a communications demultiplexer 301 (which here takes the form of a remote I/O interface) does not necessarily come from the I/O interface 816, but for example from a separate local area network interface or local bus interface of the programmable controller 815. A very closely corresponding simplification to the cabling that needs to be installed and tested at the shipyard can be achieved by following the approaches illustrated in figs. 3 and 4, with the exception that the line drawn from the programmable controller 815 would not go directly inside the tank room 808 but to an immediately associated cabinet.

Fig. 9 illustrates an example of connections that could go to and from a tank room 302 (or a combination of a tank room with an immediately associated cabinet, if one of the approaches illustrated in figs. 3 of 4 was taken). The connections 901 and 902 for drawing liquid gas from a tank and for outputting vaporized gas (both towards gas-fuelled engines and through a pressure build-up connection back to the tank(s)) are self-explanatory and part of every tank room construction. The connections 903 and 904 for the circulation of a heat exchanging medium, such as a mixture of glycol and water, are similarly self- explanatory for every tank room that encloses a vaporizer to which the heat exchanging medium comes from an external supply. Similarly easy to recognize are the connections 905 and 906 for ventilating the inside of the tank room (and possibly also the inside of an associated cabinet), as well as the connection 907 for inputting an inerting medium, such as hydrogen, and the connection 908 for leading out gas from vented parts of the piping.

Classification regulations typically require that closed spaces such as the tank room are equipped with sensors of both a fire detection system and a gas de- tection system. The classification regulations also require that the fire and gas detection systems are substantially independent of other control systems of the vessel. As a consequence there are typically needed dedicated output connections 909 and 910 that couple sensors of a fire detection system and a gas detection system, located in the tank room, to central units of the corre- sponding detection systems. Another connection of the same kind may be the output of an ESD (Emergency Shut Down) button located within or in association with the tank room.

The connection illustrated as 91 1 is the external connection through which the communications demultiplexer (not separately shown) receives the multiplexed control information and through which it transmits the multiplexed outputs, if it is configured to perform as a communications multiplexer for inputs from individual signal sources within the fuel storage and delivery system. It can be a bus connection of any kind that is used in sea-going vessels; for example it can be an Ethernet connection, a coaxial cable connection, or an optical fibre connection. If the connection illustrated as 91 1 does not include a carrier for electric power, and/or if the tank room contains other electric equipment than those directly coupled to the connection illustrated as 91 1 , there may be a separate electric connection 912 for delivering operating power.

Fig. 9 can also be understood as explaining certain features of a method according to an embodiment of the invention for constructing a fuel storage and delivery system for a gas-fuelled sea-going vessel. The method comprises constructing a tank room 302, which is a gastight space enclosing tank connections 901 and 902 and valves associated with them (not separately shown). The method comprises installing within or in immediate association with said tank room a communications demultiplexer, which is configured to convey multiplexed control information from an external connection 91 1 and to deliver dedicated control outputs to individual actuators that drive actions within said tank room. The method also comprises testing the response of said actuators to control outputs from said communications demultiplexer to verify their correct operation, prior to delivering the fuel storage and delivery system to the construction of said gas-fuelled sea-going vessel. All testing of this kind can be done inside the unit illustrated schematically in fig. 9.

The method may also comprise forming a common entity of the tank room and one or more gas tanks meant for storing the gaseous fuel in liquid form onboard the sea-going vessel, prior to delivering the fuel storage and delivery system to the shipyard. This may be done for example by welding an open- ended tank room by the edges of the open end to the outer shell of one or more tanks. Said common entity may also be equipped with a common support base as a part of the method, and the tank room may be equipped with an airlock at its access. Providing the access to a tank room with an airlock has been described in more detail in the co-pending patent application number XXXXXXXX of the same applicant, which at the time of writing this description is not yet available to the public.

At the shipyard the fuel storage and delivery system is installed in the sea- going vessel. The connections illustrated as 901 and 902 are made, if they were not made already as a part of assembling the fuel storage and delivery system separately. The connections 903 to 910 are made to the systems on board the sea-going vessel much like in prior art. The connection 91 1 (and possibly 912, if needed) is made, and the correct operation of the communica- tions demultiplexer is tested, which is much simpler than in prior art systems where a large number of individual control connections to and from the tank room had to be made and tested separately.

Variations and modifications to the embodiments discussed so far are possible without departing from the scope of protection defined by the appended claims. For example, the communications between human interfaces, a possible programmable controller, and the communications demultiplexer can go through different kinds of bus and/or network architectures than those shown in the exemplary embodiments. Also the engines to which the gaseous fuel is fed need not be single-fuel gas engines but they can be e.g. double fuel en- gines, which can burn both gaseous fuel and fuel oil according to a selection. All parts of the description that are related to liquefied gas can be generalized to also cover compressed gas, with the natural consequence that evaporators are replaced with pressure reducing valves.

Claims

1 . A fuel storage and delivery system for a gas-fuelled sea-going vessel, comprising:

- a tank room, which is a gastight space enclosing tank connections and valves associated with them, and

- within or in immediate association with said tank room a communications demultiplexer configured to convey multiplexed control information from an external connection and to deliver dedicated control outputs to individual actuators that drive actions within said tank room.

2. A fuel storage and delivery system according to claim 1 , wherein:

- said communications demultiplexer is additionally configured to perform as a communications multiplexer, for conveying inputs from individual signal sources into multiplexed outputs to be transmitted through said external connection.

3. A fuel storage and delivery system according to claim 1 or 2, wherein:

- the fuel storage and delivery system comprises a cabinet that is an enclosed space external to but mechanically attached with said tank room, and

- said communications demultiplexer is located within said cabinet.

4. A fuel storage and delivery system according to claim 3, wherein: - said cabinet comprises one or more solenoid valves,

- said one or more solenoid valves are configured to drive actions within said tank room through at least one pneumatic or hydraulic connections from said cabinet to said tank room.

5. A fuel storage and delivery system according to any of the preceding claims, wherein:

- said external connection is a general bus connection, which couples said communications demultiplexer to a control bus, to which also human interfaces for monitoring actions within said tank room are to be coupled.

6. A fuel storage and delivery system according to any of claims 1 to 4, wherein:

- said external connection is a dedicated bus connection, which couples said communications demultiplexer to a local bus, to which there is to be coupled a controller.

7. A fuel storage and delivery system according to claim 5 or 6, wherein:

- said communications demultiplexer is a programmable logic controller that comprises a processor and a memory for storing a program, the execution of which is configured to make the processor convey information between said external connection and said dedicated control outputs.

8. A fuel storage and delivery system according to claim 6, wherein:

- said communications demultiplexer is a remote input / output interface that is fixedly configured to convert multiplexed commands received through said external connection to said dedicated control outputs.

9. A sea-going vessel, comprising a fuel storage and delivery system according to any of the preceding claims.

10. A method for constructing a fuel storage and delivery system for a gas- fuelled sea-going vessel, comprising:

- constructing a tank room, which is a gastight space enclosing tank connec- tions and valves associated with them,

- installing within or in immediate association with said tank room a communications demultiplexer, which is configured to convey multiplexed control information from an external connection and to deliver dedicated control outputs to individual actuators that drive actions within said tank room, and - testing the response of said actuators to control outputs from said communications demultiplexer to verify their correct operation, prior to delivering the fuel storage and delivery system to the construction of said gas-fuelled sea-going vessel.