U.S. patent application number 12/673442 was filed with the patent office on 2012-02-02 for arrangement and method for improving load response in a marine vessel.
Invention is credited to Noel Dunstan, Oskar Levander, Tuomas Sipila.
Application Number | 20120028516 12/673442 |
Document ID | / |
Family ID | 38572947 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120028516 |
Kind Code |
A1 |
Levander; Oskar ; et
al. |
February 2, 2012 |
ARRANGEMENT AND METHOD FOR IMPROVING LOAD RESPONSE IN A MARINE
VESSEL
Abstract
The invention relates to an arrangement for improving load
response in a marine vessel, which vessel comprises a propulsion
system (1) including an internal combustion engine (2), a generator
(3), a main switchboard (4), and an electric propulsion unit (5). A
power bank (6) is connected to the main switchboard (4), whereby
the power bank (6) is arranged to store additional electric energy
supplied by the generator (3) by way of the main switchboard (4).
The additional energy stored in the power bank (6) is arranged to
be used together with the electric energy supplied by the generator
(3) in order to increase the load response to the electric
propulsion unit (5) at a given time.
Inventors: |
Levander; Oskar;
(Lansiturunmaa, FI) ; Sipila; Tuomas; (Turku,
FI) ; Dunstan; Noel; (Ulsteinvik, NO) |
Family ID: |
38572947 |
Appl. No.: |
12/673442 |
Filed: |
August 20, 2008 |
PCT Filed: |
August 20, 2008 |
PCT NO: |
PCT/FI08/50468 |
371 Date: |
March 19, 2011 |
Current U.S.
Class: |
440/6 |
Current CPC
Class: |
Y02T 70/5236 20130101;
B63H 21/17 20130101; B63H 23/24 20130101 |
Class at
Publication: |
440/6 |
International
Class: |
B63H 21/17 20060101
B63H021/17; B63H 21/14 20060101 B63H021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2007 |
FI |
20075613 |
Claims
1-12. (canceled)
13. An arrangement for improving load response in a marine vessel,
which marine vessel comprises a propulsion system including an
internal combustion engine, a generator driven by the internal
combustion engine, a main switchboard, a power bank connected to
the main switchboard, and an electric propulsion unit, in which
arrangement the power bank is arranged to store additional electric
energy supplied by the generator by way of the main switchboard,
wherein the internal combustion engine is arranged to primarily use
gas as fuel or that the internal combustion engine is a dual-fuel
engine, and in that the additional energy stored in the power bank
is arranged to be used together with the electric energy supplied
by the generator in order to increase the load response to the
electric propulsion unit at a given time.
14. The arrangement according to claim 13, wherein the marine
vessel further comprises other energy consumers, such as hotel
load, and in that the additional energy stored in the power bank is
arranged to be used together with the electric energy supplied by
the generator in order to increase the load response to said other
energy consumers at a given time.
15. The arrangement according to claim 13, wherein the power bank
is a battery, a capacitor, a flywheel generator or any combination
of these.
16. A method for improving load response in a marine vessel, which
marine vessel comprises a propulsion system including an internal
combustion engine, a generator, a main switchboard, a power bank
connected to the main switchboard, and an electric propulsion unit,
in which method the internal combustion engine drives the generator
and the generator supplies electric energy for driving the electric
propulsion unit, whereby the generator further supplies additional
electric energy to the power bank by way of the main switchboard,
wherein the method employs an internal combustion engine primarily
using gas as fuel or that the method employs an internal combustion
engine in the form of a dual-fuel engine, and in that the
additional electric energy stored in the power bank is supplied to
the electric propulsion unit together with the electric energy
supplied by the generator in order to increase the load response to
the electric propulsion unit at a given time.
17. The method according to claim 16, wherein marine vessel further
comprises another energy consumer, such as hotel load, and in that
the additional energy stored in the power bank is supplied to said
other energy consumer together with the electric energy supplied by
the generator in order to increase the load response to said other
energy consumers at a given time.
18. The method according to claim 16, wherein a battery, a
capacitor, a flywheel generator, or any combination of these is
employed as the power bank.
Description
TECHNICAL FIELD
[0001] The invention relates to an arrangement for improving load
response in a marine vessel, which vessel comprises a propulsion
system including an internal combustion engine, a generator, a main
switchboard, and an electric propulsion unit according to the
preamble of claim 1. The invention also relates to a method
according to the preamble of claim 7.
BACKGROUND ART
[0002] A conventional way to increase load with a diesel engine has
been to increase supply of the fuel to the cylinder. Due to the
turbocharger lag, the engine will be running at low air to fuel
ratio some time, but the load of the engine is increasing. With a
dual-fuel engine in "diesel mode", the engine is working with this
principle, but in "gas mode" the engine is run according to a
so-called otto-cycle. In gas mode (otto-cycle) increasing the
amount of fuel in a short period to increase load would lead to
pre-ignition (knocking), which is an undesirable situation for the
engine.
[0003] As the awareness of the environment is increasing, gas
engines are becoming more common for power production also in
marine applications due to their lower emission levels.
[0004] In special vessel types, such as tugboats, the load response
of the engine is a critical issue.
[0005] An object of the present invention is to provide an
arrangement for improving load response in a marine vessel, which
arrangement avoids the problems encountered in connection with
prior art and which provides a simple and reliable solution. These
objects are attained by an arrangement according to claim 1 and a
method according to claim 7.
SUMMARY OF THE INVENTION
[0006] The basic idea of the invention is to provide an
environmentally sound way to deliver a high load response in marine
vessels. This is achieved by having a power bank connected to the
main switchboard on the marine vessel. The power bank is arranged
to store additional energy provided by the internal combustion
engine generator combination by way of the main switchboard. For
increasing load response, the additional energy stored in the power
bank together with the electric energy delivered by the generator
are supplied to the electric propulsion unit of the marine vessel
in order to meet high load response demand at given times.
[0007] The electric propulsion units provide the entire propulsive
power, whereby the entire power of the motors can be used for
instantaneous load change.
[0008] The marine vessel may further comprise other energy
consumers, such as hotel load. In this case the additional energy
stored in the power bank is advantageously arranged to be used
together with the electric energy supplied by the generator also
for powering said other energy consumers in order to increase the
load response of said other energy consumers at a given time.
[0009] In view of environmental aspects, the internal combustion
engine is advantageously arranged to primarily use gas as fuel.
Consequently, if the internal combustion engine is a dual-fuel
engine, the dual-fuel engine is preferably arranged to be driven in
a gas mode. Dual fuel engines are less responsive than similar
diesel fuelled engines.
[0010] Dual-fuel engines driven in diesel mode and diesel engines,
however, are also widely used in applications were load response is
critical. The present invention may also advantageously be applied
to dual-fuel engines driven in diesel mode as well as diesel
engines. Diesel driven engines are also going to longer load
response times as the mean effective pressure increases
(corresponds to engine output and efficiency).
[0011] A further advantage with the present invention is that the
power bank may also be used to cover total electric load in port
operation. The power bank can be used to assist propulsion in load
transients or it can be used as a primary source of energy for
other consumers, e.g. hotel load. This means that in an emission
sensitive area, like a port, the marine vessel can be operated
without running the engines.
[0012] The power bank is advantageously a battery, a capacitor, a
flywheel generator or any combination of these.
[0013] The preferable embodiments of the method according to the
invention are given in claims 8-12.
BRIEF DESCRIPTION OF DRAWINGS
[0014] In the following the invention will be described, by way of
example only, with reference to the accompanying schematic
drawings, in which
[0015] FIG. 1 illustrates a first embodiment of an arrangement
according to the present invention, and
[0016] FIG. 2 illustrates a second embodiment of an arrangement
according to the present invention.
DETAILED DESCRIPTION
[0017] FIG. 1 shows a general layout of a propulsion system 1 of a
marine vessel in a first embodiment of an arrangement according to
the present invention. The propulsion system includes, in this
embodiment, three so-called gensets, i.e. three internal combustion
engines 2 with three respective generators 3. The generators 3 are
coupled to a main switchboard (AC) 4. The propulsion system 1 also
includes three electric propulsion units 5. Two of the electric
propulsion units are shown as azimuthing thrusters and one as a
tunnel thruster. The number and type of electric propulsion units
may of course vary depending on the type of marine vessel. Variable
speed drive of the electric propulsion units 5 is normally achieved
by using converters (AC-DC-AC) 51 between the electric propulsion
units 5 and the main switchboard (AC) 4.
[0018] The arrangement according to the invention further includes
two power banks (DC) 6, which are connected to the main switchboard
(AC) through respective inverters (DC-AC) 61. The power bank could
be a battery, a capacitor, a fly-wheel generator or any combination
of these.
[0019] Reference numeral 8 indicates an additional energy consumer,
such as hotel load, which also is connected to the main switchboard
4.
[0020] In a marine vessel comprising a propulsion system as
described above, the internal combustion engines 2 drive the
generators 3 which deliver electric energy to the main switchboard
(AC) 4. The electric energy is then supplied to the electric
propulsion units 5 by way of the main switchboard 4 and the
converters (AC-DC-AC) 51 for driving the same. At the same time,
the power banks 6 may be loaded by electric energy supplied through
the main switchboard (AC) 4 and the inverters (DC-AC) 61 for
storage.
[0021] When there is a demand for sudden load increase in view of
required output power, which is greater than what the generator
conventionally can supply, electric energy can be delivered from
both the generators 3 and the power banks 6 in order to supply a
greater load response to one or more of the electric propulsion
units 5.
[0022] The electric propulsion units provide the entire propulsive
power, whereby the entire power of the units can be used for
instantaneous load change.
[0023] In an arrangement according to the invention, the power
required by the master of the marine vessel is taken from the
bridge control instrumentation integrated into an automation
system. The automation system assesses the status of the engine
load currently being delivered and the current state of the power
bank charge. The engine load delivered is in turn assessed by the
automation system by sampling the power, i.e. the electric energy
being produced at the generator(s). The state of charge of the
power bank is assessed by the electronics in the automation
system.
[0024] These two points of system information are important to
calculate how the power requirement is to be achieved.
[0025] Changing engine loads requires that a protocol is followed.
This protocol is integrated into the automation system. Given the
state of engine load, the engine is taken through load steps to
achieve the required output power by the automation system. Given
the time to perform this load step, the automation system
determines the optimal procedure for discharging the power bank(s)
to enhance the load response. The automation system considers the
current state of charge of the power bank(s) to ensure the power
bank(s) is discharged to sufficiently cover the difference of
required power to current engine power.
[0026] Control of the extent of discharge is also exercised by the
automation system to ensure the power bank(s) is not discharged to
the detriment of the power bank life.
[0027] If there is a demand for sudden load increase for the other
energy consumer 8, it can be met in the same way both from the
generators 3 and the power banks 6 by a combined supply of electric
energy as described above.
[0028] The invention is particularly advantageous using internal
combustion engines primarily using gas as fuel. In the case of a
dual fuel engine, the dual fuel engine is preferably driven in gas
mode. Load response in gas operation is inferior in view of diesel
operation, but on the other hand gas operation is clearly more
environmental friendly than diesel operation. The increased load
response capacity provided by the power bank set-up may thus be
used to raise the load response level in gas operation to at least
an equal level, or even a higher level than the load response level
in diesel operation.
[0029] Dual-fuel engines driven in diesel mode and diesel engines,
however, are also widely used in applications were load response is
critical. The present invention may also advantageously be applied
to dual-fuel engines driven in diesel mode as well as diesel
engines. Diesel driven engines are also going to longer load
response times as the mean effective pressure increases
(corresponds to engine output and efficiency).
[0030] FIG. 2 shows a general layout of a propulsion system 1 of a
marine vessel in a second embodiment of an arrangement according to
the present invention. The propulsion system includes, in this
embodiment, three so-called gensets, i.e. three internal combustion
engines 2 with three respective generators 3. The generators 3 are
coupled to a main switchboard (DC) 4 through respective rectifiers
(AC-DC) 31. The propulsion system 1 also includes three electric
propulsion units 5. Two of the electric propulsion units could e.g.
be azimuthing thrusters and one e.g. a tunnel thruster. The number
and type of electric propulsion units may of course vary depending
on the type of marine vessel. The electric propulsion units 5 are
connected to the main switchboard (DC) 4 through respective
inverters (DC-AC) 52.
[0031] The arrangement according to the invention further includes
two power banks (DC) 6, which are connected to the main switchboard
(DC) 4. In this embodiment one of the power banks 6 is a battery
62, i.e. a chemical storage, and the other power bank is a flywheel
63, i.e. a mechanical storage. Alternatively, the power bank could
be a capacitor, on any combination of these.
[0032] Reference numeral 8 indicates an additional energy consumer,
such as hotel load, which also is connected to the main switchboard
(DC) 4 through an inverter (DC-AC) 81. Said energy consumer 8 may
also be connected to an ACbus between the generators 3 and the
respective rectifiers (AC-DC) 31 as shown by connection 82. Thus,
energy could be delivered directly to said energy consumer 8 from
the generators 3.
[0033] Reference numeral 9 indicates a surplus load heat discharge,
for dumping reverse power in situations where propulsion load is
negative, i.e. when a propeller is turning the electric propulsion
unit.
[0034] In a marine vessel comprising a propulsion system as
described above, the internal combustion engines 2 drive the
generators 3 which deliver electric energy to the main switchboard
(DC) 4 through the rectifiers (AC-DC) 31. The electric energy is
then supplied to the electric propulsion units 5 by way of the main
switchboard 4 and the inverters (DC-AC) 52 for driving the same. At
the same time, the power banks 6 may be loaded by electric energy
supplied through the main switchboard (DC) 4 for storage.
[0035] When there is a demand for sudden load increase in view of
required output power, which is greater than what the generator
conventionally can supply, electric energy can be delivered from
both the generators 3 and the power banks 6 in order to supply a
greater load response to one or more of the electric propulsion
units 5.
[0036] The electric propulsion units provide the entire propulsive
power, whereby the entire power of the motors can be used for
instantaneous load change.
[0037] In an arrangement according to the invention, the power
required by the master of the marine vessel is taken from the
bridge control instrumentation integrated into an automation
system. The automation system assesses the status of the engine
load currently being delivered and the current state of the power
bank charge. The engine load delivered is in turn assessed by the
automation system by sampling the power, i.e. the electric energy
being produced at the generator(s). The state of charge of the
power bank is assessed by the electronics in the automation
system.
[0038] These two points of system information are important to
calculate how the power requirement is to be achieved.
[0039] Changing engine loads requires that a protocol is followed.
This protocol is integrated into the automation system. Given the
state of engine load, the engine is taken through load steps to
achieve the required output power by the automation system. Given
the time to perform this load step, the automation system
determines the optimal procedure for discharging the power bank(s)
to enhance the load response. The automation system considers the
current state of charge of the power bank(s) to ensure the power
bank(s) is discharged to sufficiently cover the difference of
required power to current engine power.
[0040] Control of the extent of discharge is also exercised by the
automation system to ensure the power bank(s) is not discharged to
the detriment of the power bank life.
[0041] If there is a demand for sudden load increase for the other
energy consumer 8, it can be met in the same way both from the
generators 3 and the power banks 6 by a combined supply of electric
energy as described above.
[0042] In this embodiment the main switchboard 4 is a DC
switchboard, which makes it easier to connect a DC-type power bank
6. In the power chain from power bank to electric propulsion unit,
this further means that a rectifier may be eliminated.
Consequently, this provides for a simple system with reduced
transmission losses.
[0043] The invention is particularly advantageous using internal
combustion engines primarily using gas as fuel. In the case of a
dual fuel engine, the dual fuel engine is preferably driven in gas
mode. Load response in gas operation is inferior in view of diesel
operation, but on the other hand gas operation is clearly more
environmental friendly than diesel operation. The increased load
response capacity provided by the power bank set-up, may thus be
used to raise the load response level in gas operation to at least
an equal level, or even a higher level than the load response level
in diesel operation.
[0044] Dual-fuel engines driven in diesel mode and diesel engines,
however, are also widely used in applications were load response is
critical. The present invention may also advantageously be applied
to dual-fuel engines driven in diesel mode as well as diesel
engines. Diesel driven engines are also going to longer load
response times as the mean effective pressure increases
(corresponds to engine output and efficiency).
[0045] The two embodiments described above are just examples and
clearly show that many variations with varying components are
possible in carrying out the present invention.
[0046] The description and drawings are only intended to clarify
the basic idea of the invention. The invention may vary within the
scope of the ensuing claims.
* * * * *