U.S. patent application number 15/459182 was filed with the patent office on 2017-06-29 for method and apparatus for supplying a gaseous fuel to an internal combustion engine.
The applicant listed for this patent is Westport Power Inc.. Invention is credited to Paul M. Blomerus, Melissa S.A. McKinnon, Bradley E. Melanson.
Application Number | 20170184056 15/459182 |
Document ID | / |
Family ID | 48652993 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170184056 |
Kind Code |
A1 |
Melanson; Bradley E. ; et
al. |
June 29, 2017 |
Method And Apparatus For Supplying A Gaseous Fuel To An Internal
Combustion Engine
Abstract
A method for supplying gaseous fuel from a tender car to an
internal combustion engine on a locomotive comprising storing the
gaseous fuel at a cryogenic temperature in a cryogenic storage tank
on the tender car; pumping the gaseous fuel to a first pressure
from the cryogenic storage tank; vaporizing the gaseous fuel at the
first pressure; and conveying the vaporized gaseous fuel to the
internal combustion engine; whereby a pressure of the vaporized
gaseous fuel is within a range between 310 bar and 575 bar.
Inventors: |
Melanson; Bradley E.;
(Vancouver, CA) ; McKinnon; Melissa S.A.;
(Vancouver, CA) ; Blomerus; Paul M.; (Vancouver,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Westport Power Inc. |
Vancouver |
|
CA |
|
|
Family ID: |
48652993 |
Appl. No.: |
15/459182 |
Filed: |
March 15, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14311321 |
Jun 22, 2014 |
9624871 |
|
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15459182 |
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|
PCT/CA2012/050931 |
Dec 21, 2012 |
|
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14311321 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F17C 2227/0135 20130101;
F17C 2223/0161 20130101; F17C 2250/01 20130101; F17C 2227/0332
20130101; F17C 2225/036 20130101; Y02T 10/32 20130101; F17C
2201/054 20130101; B61C 5/00 20130101; F02M 21/06 20130101; F17C
2205/0157 20130101; F17C 2221/032 20130101; F17C 2223/043 20130101;
F02M 21/0221 20130101; F02M 21/029 20130101; F02M 21/0218 20130101;
F17C 5/02 20130101; F17C 2250/0439 20130101; F17C 2205/0126
20130101; F17C 2227/0185 20130101; F17C 2221/033 20130101; B60Y
2200/31 20130101; F17C 2223/046 20130101; F17C 2250/0408 20130101;
F02D 19/023 20130101; Y02T 10/30 20130101; F17C 2250/0636 20130101;
Y02T 10/12 20130101; F02M 21/023 20130101; B60K 15/07 20130101;
F17C 2250/043 20130101; F17C 2225/0123 20130101; F17C 2227/0393
20130101; F02M 31/00 20130101; F17C 2250/0491 20130101; F17C
2250/03 20130101; F17C 2250/0434 20130101; F02D 19/022 20130101;
F17C 2265/066 20130101; B60K 2015/03315 20130101; Y02T 10/16
20130101; F17C 5/06 20130101; F17C 9/02 20130101; F17C 2270/0173
20130101; F02M 21/04 20130101; F02M 21/0215 20130101; F17C 2223/033
20130101; F17C 2250/032 20130101; F17C 2227/0323 20130101 |
International
Class: |
F02M 21/02 20060101
F02M021/02; F02D 19/02 20060101 F02D019/02; F17C 5/02 20060101
F17C005/02; B61C 5/00 20060101 B61C005/00; F17C 9/02 20060101
F17C009/02; F02M 21/04 20060101 F02M021/04; F02M 21/06 20060101
F02M021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2011 |
CA |
2762697 |
Claims
1. A method of supplying gaseous fuel from a tender car to an
internal combustion engine on a locomotive comprising: storing said
gaseous fuel at a cryogenic temperature in a cryogenic storage tank
on said tender car; pumping said gaseous fuel to a first pressure
from said cryogenic storage tank; vaporizing said gaseous fuel at
said first pressure; and conveying said vaporized gaseous fuel to
said internal combustion engine; whereby a pressure of said
vaporized gaseous fuel is within a range between 310 bar and 575
bar.
2. The method of claim 1, further comprising accumulating said
vaporized gaseous fuel whereby pressure fluctuations of said
gaseous fuel due to changing operating conditions of said internal
combustion engine are reduced.
3. The method of claim 2, wherein a mass flow rate of said internal
combustion engine is within a range of 7 kilograms/hour and 600
kilograms/hour, and said accumulation of said vaporized gaseous
fuel is within a range of 50 liters and 200 liters.
4. The method of claim 1, further comprising receiving advanced
notice of upcoming changes in operating conditions of said internal
combustion engine and proactively pumping said gaseous fuel to
increase said pressure of said vaporized gaseous fuel.
5. The method of claim 1, further comprising receiving advanced
notice of upcoming changes in operating conditions of said internal
combustion engine and increasing a rate of pumping said gaseous
fuel to increase said pressure of said vaporized gaseous fuel.
6. The method of claim 1, further comprising receiving advanced
notice of upcoming changes in operating conditions of said internal
combustion engine and decreasing a rate of pumping said gaseous
fuel to reduce pressure fluctuations above a predetermined pressure
threshold.
7. The method of claim 1, further comprising transferring waste
heat from said internal combustion engine to said gaseous fuel at
said first pressure whereby said gaseous fuel vaporizes.
8. The method of claim 7, wherein said waste heat is transferred
from an engine coolant to a heat exchange fluid, and said heat
exchange fluid transfers heat to said gaseous fuel at said first
pressure.
9. The method of claim 8, further comprising heating said heat
exchange fluid with a supplementary heat source.
10. The method of claim 9, wherein said supplementary heat source
is one of a gas boiler and an electric heater.
11. The method of claim 10, wherein when said supplementary heat
source is said gas boiler, said gas boiler generates heat by
combusting said gaseous fuel from said cryogenic storage tank.
12. The method of claim 11, wherein said gaseous fuel is vent gas
from said cryogenic storage tank.
13. The method of claim 1, further comprising reducing conveyance
of said vaporized gaseous to said internal combustion engine in
response to a decrease in said pressure of said vaporized gaseous
fuel below a predetermined pressure threshold.
14. The method of claim 1, wherein said gaseous fuel is natural
gas.
15. The method of claim 1, further comprising: delivering low
pressure air from a compressed air supply on said locomotive to
said tender car; pressurizing said low pressure air to a high
pressure; delivering said high pressure air to said locomotive; and
forming a gaseous-fuel/air mixture by mixing said vaporized gaseous
fuel and said high pressure air on said locomotive.
16. The method of claim 15, wherein said gaseous-fuel/air mixture
is directly introduced into combustion chambers in said internal
combustion engine.
17. The method of claim 1, wherein said vaporized gaseous fuel is
conveyed to said locomotive in the form of a gaseous-fuel/air
mixture, the method further comprising: delivering low pressure air
from a compressed air supply on said locomotive to said tender car;
pressurizing said low pressure air to a high pressure on said
tender car; and forming said gaseous-fuel/air mixture by mixing
said vaporized gaseous fuel and said high pressure air on said
tender car.
18. The method of claim 15, wherein said gaseous-fuel/air mixture
is directly introduced into combustion chambers in said internal
combustion engine.
19. The method of claim 1, further comprising: pressurizing low
pressure air on said locomotive to a high pressure; and forming a
gaseous-fuel/air mixture by mixing said vaporized gaseous fuel and
said high pressure air on said locomotive.
20. The method of claim 19, wherein said gaseous-fuel/air mixture
is directly introduced into combustion chambers in said internal
combustion engine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/311,321 filed Jun. 22, 2014, and a continuation of
International Application No. PCT/CA2012/050931 having an
international filing date of Dec. 21, 2012, entitled "Method And
Apparatus For Supplying A Gaseous Fuel To An Internal Combustion
Engine". The '931 international application claimed priority
benefits, in turn, from Canadian Patent Application No. 2,762,697
filed on Dec. 22, 2011. The '931 international application is
hereby incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The present application relates to supplying a gaseous fuel
from a store of the gaseous fuel on a tender car to an internal
combustion engine of a locomotive for combustion.
BACKGROUND OF THE INVENTION
[0003] Since the early 1980s several research projects and
demonstration programs have attempted to employ natural gas as a
fuel for locomotives. The initial motivation was to determine if
any reduction in emission levels could be obtained compared to
diesel locomotives, while maintaining the same level of power.
These efforts were driven by evolving emission standards for
locomotives from the Environment Protection Agency (EPA), for which
in 1997 the EPA established Tier 0, 1 and 2 standards, and more
recently in 2008 they set the Tier 3 and 4 standards. Both the Tier
3 and 4 standards dramatically reduce emissions of diesel
particulate matter (PM) and nitrogen oxide (NOx). Out of these
efforts only one commercially available, proven and tested natural
gas fuelled line-haul locomotive emerged, which employed a low
pressure injection technology. In a paper titled "An Evaluation of
Natural Gas-fueled Locomotives", published in November 2007 by BNSF
Railway Company, Union Pacific Railroad Company (UPRR), the
Association of American Railroads, (together known as the
Railroads) and the California Environmental Associates, the
Railroads position on natural gas fuelled locomotives was
presented. Except for some potential niche applications, the
Railroads did not believe there is an opportunity to use natural
gas as a locomotive fuel to help meet emissions and performance
goals. This position was based on the one known commercially
available natural gas fuelled line-haul locomotive available in
North America. This product was a conversion kit for the EMD 645
two-stroke diesel engine that enables the locomotive to run on
liquefied natural gas (LNG) as a primary fuel, while employing
diesel as a pilot fuel. The LNG fuel is vaporized and injected at
low pressure (85-125 pounds per square inch (psi)) such that the
fuel and air mix during compression. A small portion of diesel
"pilot" fuel is then injected into the cylinder at the top of the
stroke where it auto-ignites to facilitate combustion.
[0004] Several of the research projects and demonstration programs
attempted high pressure injection techniques where natural gas fuel
was injected late in the compression cycle. In 1992 the UPRR began
two of these efforts in separate programs with Electro Motive
Diesel (EMD) and GE Transportation Systems (GE) to investigate the
use of natural gas in line-haul, high-horsepower locomotive
engines. This was a significant, multi-year effort in which UPRR
expended over $15 million exploring basic engine and fueling
technology issues. The natural gas injection pressures employed in
both the EMD and GE systems were in the range between 3000 psi and
4500 psi. Due to technical limitations, the locomotives developed
separately by EMD and GE were incapable of revenue operation. The
technical difficulties in both programs included failure of gas
injectors, cryogenic LNG pumps for handling the cryogenic fuel
between the tender tanks and the locomotives, the engine control
system software, the gas transition control system software, and
fuel system joint leaks.
[0005] The conversion kit for the EMD 645 developed out of a
project started by Burlington Northern Railroad (BN) in 1987
involving a two pronged effort to develop natural gas fueling
infrastructure and line-haul locomotives capable of running on
natural gas. For the fueling infrastructure, BN worked with Air
Products and Chemicals (APC) to develop fueling locations and
cryogenic tank equipped tender cars to support the use of
Refrigerated Liquid Methane (RLM), a high purity form of liquefied
natural gas, as a locomotive fuel. In a paper titled "LNG as a Fuel
for Railroads: Assessment of Technology Status and Economics",
published by the Gas Research Institute in January 1993, Bob
Kirkland of APC indicates that LNG vaporization can be performed on
the locomotive or on the tender car. "As less energy is needed to
pump a liquid than to compress a gas, future tender car designs
will likely deliver liquid to a pump located on the locomotive and
upstream of the vaporizer. It would be impractical, according to
Bob Kirkland of Air Products, for the tender car to supply high
pressure liquid to the locomotive. Such an arrangement would
involve long lengths of high-pressure piping as well as additional
hardware between the locomotive and the tender car to power the
pump."
[0006] Based on the admissions of the Railroads and the results of
the research and demonstration projects cited above, it is evident
that late cycle, high pressure direct injection of natural gas in a
locomotive engine is not a straightforward or obvious undertaking.
Several technical challenges exist that have prevented a
commercially available natural gas locomotive line-haul product
from emerging that can challenge and improve upon the emissions
from so called clean diesel locomotive technologies.
[0007] The present method and apparatus provide an improved
technique for supplying a gaseous fuel from a store of the gaseous
fuel on a tender car to an internal combustion engine of a
locomotive for combustion.
SUMMARY OF THE INVENTION
[0008] An improved method of supplying gaseous fuel from a tender
car to an internal combustion engine on a locomotive comprising
storing the gaseous fuel at a cryogenic temperature in a cryogenic
storage tank on the tender car; pumping the gaseous fuel to a first
pressure from the cryogenic storage tank; vaporizing the gaseous
fuel at the first pressure; and conveying the vaporized gaseous
fuel to the internal combustion engine; whereby a pressure of the
vaporized gaseous fuel is within a range between 310 bar and 575
bar. The gaseous fuel can be natural gas, methane or other
hydrocarbon gaseous fuels. The method also comprises accumulating
the vaporized gaseous fuel such that pressure fluctuations of the
gaseous fuel due to changing operating conditions of the internal
combustion engine are reduced. A mass flow rate of the internal
combustion engine is within a range of 7 kilograms/hour and 600
kilograms/hour. The accumulation of the vaporized gaseous fuel is
within a range of 50 liters and 200 liters. The method further
comprises receiving advanced notice of upcoming changes in
operating conditions of the internal combustion engine and doing at
least one of proactively pumping the gaseous fuel to increase the
pressure of the vaporized gaseous fuel, increasing a rate of
pumping the gaseous fuel to increase the pressure of the vaporized
gaseous fuel, and decreasing a rate of pumping the gaseous fuel to
reduce pressure fluctuations above a predetermined pressure
threshold. In the method waste heat from the internal combustion
engine can be transferred to the gaseous fuel at the first pressure
such that the gaseous fuel vaporizes. The waste heat can be
transferred from engine coolant to a heat exchange fluid such that
the heat exchange fluid transfers heat to the gaseous fuel at the
first pressure. The heat exchange fluid can be heated with a
supplementary heat source, which can be a gas boiler or an electric
heater. When the supplementary heat source is the gas boiler, the
gas boiler generates heat by combusting the gaseous fuel from the
cryogenic storage tank, and the gaseous fuel which is combusted can
be vent gas. The method further comprises reducing conveyance of
the vaporized gaseous to the internal combustion engine in response
to a decrease in the pressure of the vaporized gaseous fuel below a
predetermined pressure threshold.
[0009] The method can further comprise delivering low pressure air
from a compressed air supply on the locomotive to the tender car;
pressurizing the low pressure air to a high pressure; delivering
the high pressure air to the locomotive; and forming a
gaseous-fuel/air mixture by mixing the vaporized gaseous fuel and
the high pressure air on the locomotive. The gaseous-fuel/air
mixture is directly introduced into combustion chambers in the
internal combustion engine.
[0010] The vaporized gaseous fuel can be conveyed to the locomotive
in the form of a gaseous-fuel/air mixture. The method further
comprises delivering low pressure air from a compressed air supply
on the locomotive to the tender car; pressurizing the low pressure
air to a high pressure on the tender car; and forming the
gaseous-fuel/air mixture by mixing the vaporized gaseous fuel and
the high pressure air on the tender car. The gaseous-fuel/air
mixture is directly introduced into combustion chambers in the
internal combustion engine.
[0011] The method can further comprise pressurizing low pressure
air on the locomotive to a high pressure; and forming a
gaseous-fuel/air mixture by mixing the vaporized gaseous fuel and
the high pressure air on the locomotive. The gaseous-fuel/air
mixture is directly introduced into combustion chambers in the
internal combustion engine.
[0012] An improved apparatus for supplying gaseous fuel from a
tender car to an internal combustion engine on a locomotive
comprising a cryogenic storage tank on said tender car for storing
said gaseous fuel at a cryogenic temperature; a first pump for
pumping said gaseous fuel to a first pressure from said cryogenic
storage tank; a first heat exchanger for vaporizing said gaseous
fuel at said first pressure; a conduit for conveying said vaporized
gaseous fuel from said first heat exchanger to said internal
combustion engine; a pressure sensor operatively connected with
said conduit for measuring a pressure of said vaporized gaseous
fuel; and an cryogenic controller operatively connected with said
first pump and said pressure sensor and programmed to receive
pressure signals from said pressure sensor representative of said
pressure of said vaporized gaseous fuel and to operate said first
pump to maintain said pressure of said vaporized gaseous fuel
within a range between 310 bar and 575 bar. The conduit is sized
such that it can accumulate vaporized gaseous fuel within a range
of 50 liters and 200 liters. Alternatively, an accumulator having a
volume within a range of 50 liters and 200 liters can be connected
with the conduit for accumulating vaporized gaseous fuel. There is
an engine controller for controlling operation of the internal
combustion engine. The engine controller is programmed to transmit
advanced notice of changes in operating conditions of the internal
combustion engine to the cryogenic controller. In response to the
advanced notice the cryogenic controller is programmed to change a
state of the first pump. The cryogenic controller operates the
first pump to increase the first pressure when the advanced notice
comprises an upcoming increase in mass flow rate of the vaporized
gaseous fuel. The cryogenic controller operates the first pump to
decrease a rate of pumping when said advanced notice comprises an
upcoming decrease in mass flow rate of said vaporized gaseous fuel.
There is a shut-off valve connected between the first heat
exchanger and the conduit. The shut-off valve reduces and
preferably prevents conveyance of the vaporized gaseous fuel in the
conduit when a pressure differential across the shut-off valve
reaches a predetermined threshold. The apparatus further comprises
a reservoir comprising a heat exchange fluid; a heat transfer pump
operatively connected with the reservoir to pump the heat exchange
fluid; and a second heat exchanger receiving the heat exchange
fluid under pressure from the heat transfer pump and operative to
transfer waste heat from a coolant of the internal combustion
engine to the heat exchange fluid; such that the heat exchange
fluid is circulated through the first exchanger for vaporizing the
gaseous fuel at the first pressure. There can be a supplementary
heat source for heating the heat exchange fluid. The supplementary
heat source can be a gas boiler or an electric heater. The gas
boiler generates heat by combusting the gaseous fuel from the
cryogenic storage tank, and the gaseous fuel which is combusted can
be vent gas. There is also a transfer pump operative to pump the
gaseous fuel from the cryogenic storage tank to an intermediate
pressure lower than the first pressure. The first pump is operative
to pump the gaseous fuel from the intermediate pressure to the
first pressure. The cryogenic storage tank can comprise a tank port
and the transfer pump comprises an inlet and an outlet. The
transfer pump is disposed in the tank port such that the inlet is
inside the cryogenic storage tank. In alternative embodiments the
apparatus comprises a supplementary vessel connected with the
cryogenic storage tank. The supplementary vessel comprises a tank
port and the transfer pump comprises an inlet and an outlet. The
transfer pump is disposed in the tank port such that the inlet is
inside the supplementary vessel. The gaseous fuel can be natural
gas or methane.
[0013] The apparatus can comprise a supply of low pressure air
located on the locomotive. A multi-stage compression apparatus on
the tender car pressurizes the low pressure air to a high pressure.
A second conduit delivers the low pressure air to the multi-stage
compression apparatus. A mixing apparatus on the locomotive forms a
gaseous-fuel/air mixture by mixing the high pressure air and the
vaporized gaseous fuel. A third conduit delivers the high pressure
air from the multi-stage compression apparatus to the mixing
apparatus. The gaseous-fuel/air mixture is directly introduced into
combustion chambers of the internal combustion engine.
[0014] The vaporized gaseous fuel can be conveyed to the locomotive
through the conduit in the form of a gaseous-fuel/air mixture. The
apparatus comprises a supply of low pressure air on the locomotive.
A multi-stage compression apparatus on the tender car pressurizes
the low pressure air to a high pressure. A second conduit delivers
the low pressure air to the multi-stage compression apparatus. A
mixing apparatus on the tender car forms the gaseous-fuel/air
mixture by mixing the high pressure air and the vaporized gaseous
fuel. The gaseous-fuel/air mixture is directly introduced into
combustion chambers of the internal combustion engine.
[0015] The apparatus can comprise a supply of low pressure air on
the locomotive. A multi-stage compression apparatus on the
locomotive pressurizes the low pressure air to a high pressure. A
mixing apparatus on the locomotive forms the gaseous-fuel/air
mixture by mixing the high pressure air and the vaporized gaseous
fuel. The gaseous-fuel/air mixture is directly introduced into
combustion chambers of the internal combustion engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic view of an apparatus for supplying
gaseous fuel to an internal combustion engine according to one
embodiment.
[0017] FIG. 2 is a pictorial view of a tender car according to the
embodiment of FIG. 1;
[0018] FIG. 3 is a pictorial view of a tender car according to the
embodiment of FIG. 1;
[0019] FIG. 4 is a pictorial view of a tender car according to the
embodiment of FIG. 1;
[0020] FIG. 5 is a schematic view of an apparatus for supplying
gaseous fuel to an internal combustion engine according to a second
embodiment.
[0021] FIG. 6 is a schematic view of an apparatus for supplying
gaseous fuel to an internal combustion engine according to a third
embodiment.
[0022] FIG. 7 is a pictorial view of a tender car according to the
embodiment of FIG. 1
[0023] FIG. 8A is a schematic view of an arrangement of a tender
car and two locomotives.
[0024] FIG. 8B is a schematic view of an arrangement of a tender
car and three locomotives.
[0025] FIG. 8C is a schematic view of an arrangement of three
tender cars and three locomotives.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0026] Referring to FIG. 1, fuel apparatus 10 is shown for
supplying a gaseous fuel from tender car 20 to internal combustion
engine 30 on locomotive 40. Tender car 20 supplies gaseous fuel for
combustion in engine 30 and is connected with and hauled by
locomotive 40. Cryogenic storage tank 50 is an ISO tank that stores
the gaseous fuel at cryogenic temperatures in a liquid phase. As
used herein, a gaseous fuel is any fuel that is in a gaseous phase
at standard temperature and pressure. The gaseous fuel in tank 50
is LNG in the present example, but in other embodiments the gaseous
fuel can refrigerated liquid methane (RLM) or other hydrocarbon
fuels. Tank 50 is securely connected with tender car 20 when
supplying gaseous fuel for engine 30, and is also detachable such
that an empty tank on the tender car can be replaced with a full
tank. Tank 50 comprises a fill receptacle and a pressure relief
valve to release pressure inside the tank when it builds up beyond
predetermined acceptable levels. Cryogenic electronic controller
140 communicates with tank 50 to receive information related to a
quantity of LNG remaining in the tank, and this information can
comprise a level of LNG in the tank, vapor pressure within the
tank, and a temperature of LNG within the tank. In the present
example cryogenic controller 140 is a computer comprising a
processor and memories, including a permanent memory, such as FLASH
or EEPROM, and a temporary memory, such as SRAM or DRAM, for
storing and executing a program.
[0027] Low pressure liquid fuel pump 60 transfers LNG at low
pressure from tank 50 to high pressure liquid fuel pump 70 in high
pressure gas supply system 80. As used herein, gas refers to
gaseous fuel. Low pressure pump 60 is shown located between tank 50
and high pressure pump 70 in the present example. In other
embodiments pump 60 can be located completely within tank 50 or in
a tank port such that an inlet of the pump is disposed inside the
tank and an outlet is disposed outside the tank. The tank port can
also be provided in a secondary vessel connected with tank 50. The
secondary vessel couples tank 50 to pump 60 such that the secondary
vessel is flooded with LNG from tank 60 and the inlet of the pump
is immersed in the LNG in the secondary vessel. It is advantageous
to locate low pressure pump 60 such that it can be efficiently
maintained at an operational temperature and can be conveniently
accessed for maintenance. The operational temperature for pump 60
is close to the boiling temperature of the cryogenic fluid (LNG)
such that the fluid does not vaporize in the pump while being
pressurized from the inlet to the outlet. In light of the desired
advantages the preferred location for pump 60 is in the tank port.
However, other factors such as interoperability with existing ISO
tanks may require placement of pump 60 in the other locations. In
other embodiments, pump 60 and the secondary vessel can be located
on high pressure gas supply system 80. In yet other embodiments
pump 60 may not be required such that pump 70 receives LNG directly
from tank 50. In still further embodiments, pump 70 can be located
within another secondary vessel which is flooded with LNG either
directly from tank 50 or from pump 60.
[0028] High pressure pump 70 pressurizes the LNG from low pressure
pump 60 and supplies pressurized liquid fuel to heat exchanger 90
which vaporizes the LNG into a gaseous phase. The gaseous fuel is
conveyed from heat exchanger 90 to engine 30 through conduit 100,
solenoid valve 110 and conduit 120. Cryogenic controller 140
communicates with pressure sensor 150 to receive information
related to the pressure of the gaseous fuel in conduit 120 and
commands pumps 60 and 70 to operate in order to maintain a
predetermined pressure threshold in conduit 120. The pressure of
the gaseous fuel in conduit 120 is maintained between a range of
310 bar (.about.4500 psi) and 575 bar (.about.8340 psi) which
covers a range of injection pressures for direct fuel injectors
(not shown) in engine 30. Injection pressure within this range
allows sufficient mass flow rate of gaseous fuel to meet full load
operating requirements for engine 30. In addition, as the injection
pressure is increased there is a reduction in emissions, and
especially in particular matter (PM).
[0029] Valve 110 is commanded by controller 140 to open and close
depending upon operating and fault conditions to allow or prevent
gaseous fuel from entering conduit 120. Valve 110 also operates as
an automatic shutoff valve that automatically closes (without
command from controller 140) when the pressure differential across
an inlet and an outlet of valve 110 reaches a predetermined
magnitude such that conveyance of the gaseous fuel in conduit 120
is reduced, minimized or preferably stopped. This is advantageous
in the situation when the tender car 20 accidently breaks away from
locomotive 40 while conduit 120 is connected therebetween, in which
case the pressure in conduit 120 will suddenly decrease whereby the
pressure differential across valve 110 will increase above the
predetermined magnitude. In other embodiments valve 110 can be two
valves where one valve is commanded by controller 140 to open and
close, and the other valve automatically closes based on the
inlet-to-outlet pressure differential.
[0030] There are other valves (not shown) on tender car 20 that are
actuated by compressed air. A compressed air supply (not shown) can
be located on locomotive 40, on tender car 20 or in high pressure
gaseous fuel system 80. The solenoid of valve 110 can actuate a
valve that controls the flow of gaseous fuel directly, or it can
actuate a valve that controls the flow of compressed air to another
valve that controls the flow of gaseous fuel.
[0031] The compressed air supply can be employed for enriching
gaseous fuel before it is directly introduced into combustion
chambers in engine 30 on locomotive 40. The gaseous-fuel/air
mixture provides an increased equivalence ratio in fuel jets in the
combustion chambers of engine 30 resulting in improved combustion
characteristics and reduced emissions. There are various techniques
for providing a gaseous-fuel/air mixture, such as disclosed in the
Applicant's co-pending Canadian Patent Application titled
"Air-Enriched Gaseous Fuel Direct Injection For An Internal
Combustion Engine", filed on Dec. 17, 2012, which is incorporated
by reference herein in its entirety. In one such technique, air
from the compressed air supply on locomotive 40 is further
compressed in a multi-stage compression apparatus on the locomotive
to a high pressure. Air from the compressed air supply is
approximately 6 bar and can be considered low pressure air. High
pressure air from multi-stage compression apparatus is in the range
of 155 bar to 575 bar depending upon the technique of mixing air
with gaseous fuel and the required injection pressure of the
gaseous-fuel/air mixture. High pressure air is mixed with gaseous
fuel from conduit 120 in a mixing apparatus on locomotive 40, and
the gaseous-fuel/air mixture is introduced directly into combustion
chambers of engine 30. In another technique, air from the
compressed air supply on locomotive 40 is delivered to the
multi-stage compression apparatus that is now located in high
pressure gas supply system 80 on tender car 20. The multi-stage
compression apparatus pressurizes air to the high pressure. In this
technique, the mixing apparatus can be located in supply system 80
such that the gaseous-fuel/air mixture is delivered to locomotive
40 over conduit 120, or can be located on locomotive 40 as in the
previous technique such that conduit 120 delivers gaseous fuel and
another conduit delivers high pressure air to the mixing apparatus
on locomotive 40.
[0032] The maximum mass flow rate requirement for engine 30
operating at full load is very large, for example around 600 kg/hr.
In contrast the idling flow rate requirement for engine 30 is
substantially reduced, for example around 7 kg/hr. Depending upon
operating conditions, the instantaneous mass flow rate can vary
dramatically between the maximum and idling flow rate requirements.
In order to avoid excessive pressure fluctuations in conduit 120,
which lead to a reduction in combustion performance and in engine
operating stability, accumulator 130 is connected with conduit 100
and acts as a gas buffer that filters pressure fluctuations that
occur when instantaneous flow rate requirements for engine 30
change. Based on the mass flow rate requirements for engine 30,
accumulator 130 comprises a gas buffer volume within a range of 50
liters and 200 liters. In other embodiments accumulator 130 can be
replaced by sizing conduit 100 and/or conduit 120 accordingly.
[0033] Returning to heat exchanger 90, its operation will now be
further described. Reservoir 160 comprises heat exchange fluid, for
example glycol, that circulates in heat exchanger 90 to vaporize
the LNG. The heat exchange fluid is transferred through heat
exchanger 170 by heat transfer pump 180 such that waste heat in
coolant from engine 30 increases its temperature. The coolant from
engine 30 is conveyed over conduit 190 and circulates in heat
exchanger 170 from which it returns to the engine. The heat
exchange fluid is conveyed over conduit 200 to high pressure gas
supply system 80, where it circulates through heat exchanger 90 and
transfers heat to and vaporizes the LNG. Depending upon how the
instantaneous mass flow rate for engine 30 changes based on varying
operating conditions, there may not be enough waste heat from
engine 30 to meet the vaporization load in heat exchanger 90. In
this situation, supplementary heat exchange system 210 can increase
the temperature of the heat exchange fluid in conduit 200 before it
circulates in heat exchanger 90. System 210 comprises a gas boiler
with an isolated combustion air intake and discharge (similar to a
sealed combustion residential gas fireplace or industrial radiant
heater) that burns gaseous fuel in conduit 220 from tank 50.
Conduit 220 conveys vent gas and/or gas vapor from within tank 50
to heat exchange system 210. The heat exchange fluid from conduit
200 is circulated through heat exchange system 210, where its
temperature can be increased, and transferred over conduit 230 to
heat exchanger 90, from which it returns to reservoir 160 over a
return conduit (not shown). Heat transfer pump 180 pressurizes the
heat exchange fluid to enable its circulation as described above.
As would be understood by those familiar with the technology
involved here, heat transfer pump 180 can be located at alternative
locations in the above described arrangement of components as
illustrated in FIG. 1 that achieve the same result, and such
alternative locations are considered within the scope the present
disclosure. Similarly, reservoir 160 can be located on locomotive
40, tender car 20 and within high pressure gas supply system
80.
[0034] Gas vent system 310 comprises a burner and a low pressure
gas accumulator with an outlet regulator. The accumulator captures
gas vented from tank 50. Captured gas is flow regulated to the
burner to reduce Greenhouse gas emissions. Heat exchange system 210
can be employed to burn gas captured by gas vent system 310.
[0035] Conduits 120 and 200 provide a quick connect and disconnect
feature that enables these conduits to non-destructively divide
into two parts each such that locomotive 40 and tender car 20 can
move apart from each other. Shut-off valve 110 blocks the flow of
gaseous fuel when conduit 120 divides into two parts in the event
of an accidental break-away between locomotive 40 and tender car
20. A shut-off valve can also be provided on locomotive 40 to
prevent the heat exchange fluid from spilling out when conduit 200
divides into two parts. As an alternative conduit 200 can comprise
a self-closing disconnect which closes when conduit 200 disconnects
into two parts, and opens when conduit 200 is connected into one
part.
[0036] Cryogenic controller 140 communicates with engine electronic
controller 240 to receive a feed forward parameter representative
of gas demand from engine 30 and to transmit meaningful fault
information to enable intelligent decision making on engine 30 if
fuel supply is not sufficient for desired operating point. Engine
controller 240 is a computer comprising a processor and memories,
including a permanent memory, such as FLASH or EEPROM, and a
temporary memory, such as SRAM or DRAM, for storing and executing a
program. Engine controller 240 commands the direct fuel injectors
to open and close valves therein to inject gaseous fuel into
cylinders (not shown) in engine 30 and receives signals from
sensors (not shown) that monitor operational parameters of the
engine. Controller 240 is also responsive to command signals from a
locomotive operator communicated by locomotive electronic
controller 270 to change the current operating state of engine 30.
In response to the sensor signals and the command signals, engine
controller 240 informs cryogenic controller 140 of an upcoming
change in the quantity of gaseous fuel that will be injected into
the cylinders in engine 30 and a corresponding change in the
instantaneous mass flow through conduit 120. In response to this
advance notice, cryogenic controller 140 can take proactive
measures to prepare for the upcoming change by adjusting the
current state of pumps 60 and 70. For example, in response to an
upcoming increase in the mass flow rate in conduit 120 controller
140 can proactively begin to operate pumps 60 and/or 70, or
increase a rate of pumping by increasing the operating speed of
pumps 60 and/or 70 if they are already operating, to increase the
pressure in conduit 120 such that an undershoot pressure
fluctuation below a predetermined lower pressure threshold is
reduced, minimized or preferably prevented. Similarly, in response
to an upcoming decrease in the mass flow rate in conduit 120
controller 140 can proactively begin decreasing the rate of pumping
by decreasing the operating speed of pumps 60 and 70 such that an
overshoot pressure fluctuation above a predetermined upper pressure
threshold is reduced, minimized or preferably prevented. Cryogenic
controller 140 also communicates with telemetry module 320 and
informs the telemetry module, engine controller 240 and locomotive
controller 270 of faults detected in the components it communicates
with, and whether any operational parameters monitored by it are
not within predetermined ranges or compliant with predetermined
thresholds. Telemetry module 320 communicates wirelessly with a
locomotive command center and transmits the data it receives from
controller 140, such as tank pressure, tank level and tender car
diagnostics. Locomotive controller 270 is a computer comprising a
processor and memories, including a permanent memory, such as FLASH
or EEPROM, and a temporary memory, such as SRAM or DRAM, for
storing and executing a program.
[0037] Referring to FIG. 2, tender car 20 further comprises flat
car 280 on which cryogenic storage tank 50 and high pressure
gaseous fuel supply system 80 are mounted. In FIG. 3, tender car 20
comprises two storage tanks 50 and two supply systems 80, one for a
locomotive at either end of well car 281. In other embodiments
there can one storage tank 50 and one supply system 80 associated
with well car 281. In the embodiment of FIG. 7, both storage tank
50 and supply system 80 are located within the well of well car
281. FIG. 4 illustrates cryogenic rail tank car 300 that has been
modified to accommodate high pressure gas supply system 80.
Cryogenic rail tank car 300 is conventionally employed to haul
cryogenic fluids, and in FIG. 4 it is shown adapted to act as the
tender car for locomotive 40. As depicted in FIG. 4, key interface
points between the three main subsystems comprise rail car chassis
290, cryogenic storage tank 51 and high pressure gaseous fuel
supply system 80. In other embodiments rail car chassis comprises a
support extending underneath and supporting storage tank 51.
Referring now to FIGS. 8A, 8B and 8C, there are shown examples of
advantageous combinations of tender car(s) 20 and locomotive(s) 40
that employ one or more high pressure gas supply systems 80. In
these examples, the tender cars can be the ones shown in FIGS. 2,
3, 4 and 7. In FIG. 8A, one tender car 20 supplies gaseous fuel for
two locomotives 40 located at opposite ends of the tender car. In
FIG. 8B, one tender car 20 supplies gaseous fuel for three
locomotives 40 located in sequential order adjacent one end of the
tender car. In FIG. 8C, three tender cars 20 arranged in sequential
order supply gaseous fuel for three locomotives 40 also arranged in
sequential order adjacent the tender cars. There are other
advantageous combinations of tender cars 20 and locomotives 40.
[0038] With reference to the schematic view of FIG. 5, there is
shown a second embodiment of fuel apparatus 10 that is similar to
the embodiment of FIG. 1 and like parts have like reference
numerals and are not described in detail, if at all. Heat exchange
system 211 comprises an electric heater (not shown) that receives
electrical power from electric generator 240 over conduit 250.
Similar to heat exchange system 210, depending upon the current
operating state and operating history of engine 30, the electric
heater in system 211 can increase the temperature of the heat
exchange fluid in conduit 200 before the fluid is circulated in
heat exchanger 90. In other embodiments heat exchange system 211
can be located on locomotive 40.
[0039] With reference to the schematic view of FIG. 6, there is
shown a third embodiment of fuel apparatus 10 that is similar to
the embodiment of FIG. 1 and like parts have like reference
numerals and are not described in detail, if at all. High pressure
gas supply system 80 is located on locomotive 40. This is
advantageous since conduit 260 between pumps 60 and 70, which now
runs between tender car 20 and locomotive 40, is at a low pressure
which reduces the length of high pressure conduit overall. A
similar modification to the embodiment of FIG. 5 can be made.
[0040] While particular elements, embodiments and applications of
the present invention have been shown and described, it will be
understood, that the invention is not limited thereto since
modifications can be made by those skilled in the art without
departing from the scope of the present disclosure, particularly in
light of the foregoing teachings.
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