CA2194223A1

CA2194223A1 - Method and apparatus for fueling vehicles with liquefied cryogenic fuel

Info

Publication number: CA2194223A1
Application number: CA002194223A
Authority: CA
Inventors: Richard John Kooy; Mervyn Ladd Conrad; David John Forgash; Raymond Korzonas; Bryan Patrick Neuhalfen; George D. Rhoades; Jack Wayne Sudduth
Original assignee: Individual
Current assignee: Chicago Bridge and Iron Technical Services Co
Priority date: 1994-07-01
Filing date: 1995-03-15
Publication date: 1996-01-18
Also published as: US5687776A; BR9508216A; JPH10512940A; WO1996001391A1

Abstract

Apparatus for and method of, withdrawing liquefied cryogenic fuel stored in a primary insulated storage tank (12) at a low pressure and at a temperature close to its boiling point; increasing the pressure (22) of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger (36) to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition; and feeding the said warmed and pressurized liquefied cryogenic fuel to an insulated tank (42) on a vehicle at a refueling facility, said vehicle using liquefied cryogenic fuel as its fuel and the insulated vehicle fuel tank being adapted to safely contain and store the said liquefied cryogenic fuel in liquid form, at an approximate saturated condition.

Description

~WO96/01391 2 1 94223 P~

MET}IOD AND APPAR~T118 FOR :FIJELING
~E~ICLE8 ~IT~ I~IQTTF~TFn ~;KL~ F~EL

This invention relates to the storage and ~;~p~nAinq of cryogenic fuels used to fuel engines.
More particularly, this invention is ~I.c~Ll.ed with apparatus and methods for storing and ~i~~p_n~inq liquefied cryogenic fuels such as liquefied natural gas (LNG), methane, ethane, ethylene, or hYdLOg~rl as a fuel for engines in vehicles of all types.

B;9~_r~ ur~ OF T~E lr~v~

Due to the increased costs of liquid fuels, such as gasoline and diesel fuel, as the energy source for engines in automobiles, trucks, buses, boats, ships, aircraft, tractors and off-the-road construction equipment such as cranes, earthmovers and b~ ~z-rs, all of which are considered to be vehicles for the purpose of this invention, there has been increased interest in using natural gas and other cryogenic fuels to fuel such engines.
Also, in many areas of the world natural gas is abundantly available while petroleum products such as gasoline and diesel fuel are very scarce and expensive. Additionally, engines fueled with cyrogenic fuels such as methane or hydL~g~n generally produce combustion products which have a much lower polluting effect than do gasoline and diesel fuel.
Because cryogenic fuels at ambient temperature and ~i ~ ~ric pLes~uLa have a relatively low volumetric energy content it is not practical to store them at these conditions in a vehicle fuel tank. For example, it is customary to store natural gas in a fuel tank under very high Wo96/o~sl 21 ~42~3 P~

~Lasau.~s of about 2000 to 4000 psig. See Swenson et al U.S. patent 5,107,906; Pierson U.S. patent 4,987,932; Fisher et al U.S. patent 4,527,600 and Young U.S. patent 4,505,249.
It has been previously proposed to store a cryogenic liquid fuel, such as liquefied natural gas, in an insulated fuel tank at a saturated t~ -'yll~ic state wherein the liquid is in equilibrium with the vapor. Mills U.S. patent 4,406,129 discloses a cryogenic liquid fuel in a vehicle tank and the use of the liquid and vapor to fuel a vehicle engine. However, this patent does not disclose the source of the cryogenic liquid fuel, how it was ~;~p~ or filled into the vehicle tank or its t ~tUL~ and ~Lea_uLe in the tank.
It has been rec~gn; 7~ for many years that a very practical way to store bulk quantities of liquefied gases in a tank is at low ~Lasau.~s and low temperatures. For exa~ple, liquefied natural gas may be stored at a pressure of about 5 psig to 150 psig and a t aLuL~ of about -252~F to -186~F. See Maher et al U.S. patent 3,195,316.
Storing liquefied natural gas at such a low ~L~ULe in a vehicle tank, however, may be undesirable because the low pressure may be unsuitable for practical operation of some engines, particularly fuel injected engines. A need accordingly exists for ; ~vad apparatus and methods of filling a vehicle fuel tank with liquefied natural gas.

S~NNARY OF THE ~hv~n~ll According to the invention, an apparatus i5 provided co~prising a pri~ary insulated storage ~ W096101391 ~ r~a,~
2t 94223 tank containing liquefied cryogenic fuel at a low ~LesDuLe and at a temperature close to its boiling point, a heat ~hange~, a first conduit communicating with the pri-m-ary storage tank and with the heat PY~hAngQr, a pump for withdrawing liquefied cryogenic fuel from the primary tank, increasing the esDu-e of the withdrawn liquefied cryogenic fuel and feeding it through the first conduit to the heat PY~hAngPr wherein the pl~DDuLized liquefied cryogenic fuel is warmed to a subcooled or near saturated condition, a second conduit communicating with the heat Py~hAngPr and having means for ;cating with a vehicle fuel tank, receives the warmed and ~LesDuLized liquefied cryogenic fuel from the heat exchanger and feeds it to a vehicle fuel tank for storage as a liquid therein at an approximate saturated condition.
The apparatus may include a stationary cryogenic fuel ~;qpDnc;ng tank that stores warmed and ~LesDu,ized liquefied cryogenic fuel received at least in part from the heat PYrh~ng~r. A conduit able to connect to a vehicle fuel tank feeds warmed and ~es~uLized cryogenic fuel from the dispensing tank to a vehicle fuel tank.
In the apparatus of this invention, cryogenic fuel vapor which ,A - l AteS in the primary insulated storage tank can be withdrawn by a compressor and combined with the liquefied cryogenic fuel withdrawn from the primary insulated storage tank to form a combined stream which is then fed through the heat PY~hAngPr. This r~Y;m; 7PC the amount of fuel effectively used and min;m;7Pq gas emissions to the environment.
Excess vapor which forms in the dispensing tank can be reLuL1-ed to the primary insulated WO96/013gl 2 1 9 4 2 2 3 I~

storage tank, reducing gas emissions to the environment. Also, liquefied cryogenic fuel can be witharawn from the primary storage tank and be fed directly into admixture with liquefied cryogenic fuel withdrawn from the dispensing tank to form a blended mixture which is fed to the vehicle tank.
The apparatus can include a conduit for withdrawing liquefied cryogenic fuel from the primary storage tank, pL~aDuLizing the withdrawn liquefied cryogenic fuel and feeding it into admixture with warmed liquefied cryogenic fuel with-drawn from the heat ~Y~hAngPr to thereby form a blended stream of warmed and pL~sauLized liquefied cryogenic fuel to be fed either to the vehicle fuel tank or to the dispensing tank.
The apparatus can also have a conduit for withdrawing liquefied cryogenic fuel from the primary storage tank, pressurizing the withdrawn liquefied cryogenic fuel and feeding it into admix-ture with warmed liquefied cryogenic fuel withdrawnfrom the ~icp~ncing tank to thereby form a blended stream of warmed and pressurized liquefied cryogenic fuel to feed to the vehicle fuel tank.
Additionally, a conduit can be ;n~ d for with-drawing cryogenic fuel vapor from the dispensingtank and returning it to the primary storage tank.
The apparatus can also have a vertical tube ambient heat ~Y~hAng~r with a continuous horizontal bottom inlet and a continuous horizontal top outlet that m;n;mi7~c heat gain to the system.
Conventional vehicle tanks include 6elf-actuated ~L ~5~UL ~ regulators which control the ~esaule within preset limits by selectively allowing either liquid only or liquid and vapor to flow from the fuel tank to the vehicle's engine. If ~ WO96/01391 2 1 q 4 2 2 3 r~

this system fails or the vehicle is not used for prolonged periods of time and the liquid ~ UL e rises substantially, the vehicle tank p~es :UL~ may rise above its normal operating range. Stationary pumps that deliver fuel have a certain PL~S~UL~
delivery capacity that can only deliver fuel if the delivery PLeS-UL~ is greater than the vehicle fuel tank p~ ~S~UL~. The present invention R'~ ~ ' tes vehicle fuel tank pLas~uL~6 substantially above fueling system pressure by ;nrlllding, a primary insulated storage tank containing, for example, liquefied cryogenic fuel, a heat exchanger which receives liquefied cryogenic fuel that is pumped from the primary storage tank through a first conduit, and is then warmed in the heat oYrh~ngPr to a subcooled or near saturAted condition, a second conduit - ;rating with a heat exchanger and capable of _ icating with a vehicle fuel tank receives warmed and pL~s_uLized cryogenic fuel from the heat PYrh~ngPr and feeds it to a vehicle fuel tank for storage as a liquid therein at an approximate saturated condition, and a third conduit , ; rAting with the primary storage tank and being capable of communicating with a vehicle fuel tank for receiving fluid from the vehicle fuel tank and returning it to the primary tank to reduce the internal pLes~uLe of the vehicle fuel tank.
When an optional dispensing tank is used to store warmed and p~e~_uLized liquefied cryogenic fuel from the heat PYrh~ngor, the third conduit may - icate with the di~pPn~;nq tank and feed the fluid from the vehicle fuel tank to it, rather than returning warm and PL ~S~U~ ized gas to the bulk storage tank. The third conduit may include a pump or it may include a t~ L~LuLe control valve that 2 1 ~4 2 2 3 receives, via a fourth conduit, pL~s~uLized liquefied cryogenic fuel from the first conduit so that a mixture i5 fed to the vehicle fuel tank.
A method in accordance with this invention in~ Pc, withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pL~DULe and at a t~ ~tuLe close to its boiling point, increasing the pLeSDULe of the withdrawn liquefied cryogenic fuel and then feeding it through a heat exchanger to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition reducing the internal PIeS~ULe of an insulated vehicle fuel tank by returning fluid to the primary insulated storage tank (or a ~icp~ncing tank when present), the vehicle fuel tank being adapted to safely contain and store the liquefied cryogenic fuel in liquid form at an approximate saturated condition, and feeding warmed and pL~_uLized liquefied cryogenic fuel to the vehicle fuel tank.
The stationary tanks, such as the primary bulk storage tank and the dispensing tank, must maintain a certain minimum pressure as liquid is withdrawn. Conventional cryogenic storage tanks have gravity-fed natural air draft finned tube ambient heat exchangers which vaporize some of the liquid in response to the opening of a self-actuated pressure regulator. The high volumetric liquid withdrawal flow rates associated with ~;cp~ncing operations require that these ambient heat exchanger~ be very large, and a more economical means in accordance with the present invention includes a conduit ~ icating with the heat exchanger and the primary insulated tank for receiving the warmed and ples~uLized liquefied cryogenic fuel and feeding it to the primary tank to ~ WO9~01391 2 ~ 9 4 2 2 3 r ~

maintain the p~eL~uLe in the primary storage tank above a predetprminpd mini~um ~L~SSUL~. A
dlcpDncing tank may be used with this : ' '; ~.
The same objective can be achieved by practicing a method in~luAing, withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low ~r~s~uL~ and at a t~ ~LuLe close to its boiling point, increasing the ~LesauLe of the withdrawn liquefied cryogenic fuel and then feeding the yLes~uLized liquefied cryogenic fuel through a heat PY~h~ngPr to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition, and feeding it to the primary tank to maintain the pLe~auLe in the primary talik above a predetPrm;nPA
mini~um p~es~uL~.
When a dispensing tank is used with the present invention, a means for A~ ting d; cpPnc;ng volumetric fluctuations is provided which maintains the ~L~S_ULe in the dicrPncing tank as it is being filled. ~hen the di6pensing tank is being filled from a nearly empty initial condition, its internal yres~uL~ will rise above the saturation ~L~s~uL~ of the feed liquid temperature in the feed conduit because a heat load is imposed to condense the vapor in the di cpPncing tank as it is being replaced by liquid. It is undesirable to return this high pL~S~ULe gas to the primary tank on a routine basis because the liquid in the primary tank will be ~-r.Gc~c~rily warmed. An economical means to limit the ~Le~LuL~ in the dispensing tank when it is being filled i n~l lldPC a conduit communicating with the first conduit d~ .u.~LLeam of the pump and with the dispensing tank, the conduit receives ~L~s~uLized liquefied cryogenic fuel from the first conduit and feeds it to the dispensing tank to W096/0139~ 21 94223 maintain the pLesDuLe in the ~;cpanc;ng tank below a prP~otorm;nP~ maximum ~L~D~uLe.
A method for accomplishing this result includes withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low ~Le~DuL~ and at a tr _ flLuLe close to its boiling point;
increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pL~D~uLized liquefied cryogenic fuel through a heat PYrh~nflf~r to warm the liquefied cryogenic fuel to a near saturated liquid condition; feeding the warmed and pLesDuLized liquefied cryogenic fuel from the heat exchanger to a stationary insulated cryogenic fuel dispensing tank and storing the liquefied cryogenic fuel at an approximate saturated condition;
transferring liquefied cyrogenic fuel from the dispensing tank to a vehicle fuel tank; and feeding esDuLized liquefied cyrogenic fuel to the dispensing tank to maintain the ~LeJDuLe in the ~;crPnc;ng tank below a predetprm;npd maximum ~L~SDUL_.
If the vehicle fuel tank is of small capacity, then there is a need for the system to rapidly control the t-_~el-~LuL~ in a feeding conduit that mixes the output of the heat exchanger and a by-pass conduit containing pres6urized liquefied cyrogenic fuel. It is desirable to obtain a mix of liquefied cyrogenic fuel having desired properties without the use of additional rotating equipment such as pumps or CULIPLe85ULD to m;n;m;7e energy cu.._ ,Lion and maintenance requirements. Such an apparatus can include: a primary insulated storage tank containing liquefied cyrogenic fuel at a low pL~SDUL~ and at a t~ LuL~ close to its boiling point, a heat oYrh~nfJPr, a first conduit --~ W096/01391 2 ~ 94Z2 P~

icating with the primary tank and with the heat oY~hAnqor, the first conduit inrlll~;nq a pump for withdrawing liquefied cyrogenic fuel from the primary tank, increasing the pLeS~ULe of the withdrawn liquefied cyrogenic fuel and feeding it through a control valve to the heat exchanger wherein the pLesDuLized liquefied cyrogenic fuel is converted to a vapor at a predetPrmi nod pressure and near the temperature of the heat source for the heat oY~h~nqor; a reservoir in vapor i~tion with the heat exchanger for receiving and storing warmed and pressurized vaporized cryogenic fuel; a second conduit for transferring warmed and pLeS~uL ized liquefied cyrogenic fuel to a vehicle fuel tank at an approximate saturated condition; a liquid conduit communicating with the first conduit downstream of the pump and with the second conduit, the liquid conduit including a control valve for receiving and controlling the flow of pressurized liquefied cyrogenic fuel from the primary tank to the second conduit for mixture with the warmed and pressurized cryogenic fuel from the reservoir in the second conduit to form pL~uLized liquefied cyrogenic fuel at a subcooled or near saturated condition.
When a stationary dispensing tank is used, the liquid conduit and the mixed stream of warmed and pressurized cryogenic fuel is fed into a conduit that feeds the ~icponcinq tank.
A method for achieving this result ~ 30 includes withdrawing liquefied cyrogenic fuel stored in a primary insulated storage tank at a low p~essula and at a t~ aLuL close to its boiling point; increasing the pr eS~ULe and temperature of some of the withdrawn liquefied cyrogenic fuel to form pres6urized vaporized cryogenic fuel at a W096/01391 2 1 94223 T~1l~ 5 : ~

t~ ~LUL~ approaching that of a heat source;
increasing the pLasnuLa of the 1. in~r of the withdrawn liquefied cyrogenic fuel; mixing pL~nDuLized vaporized cryogenic fuel with 5 ~L asnuL ized liquefied cyrogenic fuel to form a warmed and ~L~s~uLized liquefied cyrogenic fuel at a subcooled or approxi~ate saturated condition; and transferring warmed and pressurized cryogenic fuel to a vehicle fuel tank.
The flow rate to each vehicle need not be exactly the 6ame but should be roughly equal because it is desirable to employ one or two large pumps versu6 a number of small dedicated pumps. Thus, the conduit ;rating with the vehicle fuel tank may include a flow restrictor for controlling the flow of warmed and p~ uLized liquefied cyrogenic fuel from the heat ~hAn~Gr to ~he vehicle fuel tank and a regulator for sen6ing fluid flow pLa6suLe drop acro66 the flow re6trictor and for reducing the flow 20 of warmed and ~LasnuLized liquefied cyrogenic fuel to a vehicle fuel tank in ~en~.-6e to high fluid flow ~L~snuLe drop in the restrictor.
The invention also relates to a method and apparatus for feeding liquefied cyrogenic fuel to a 25 vehicle tank in a snhcool~ or near saturated condition. An d~yaL~Lus in accordance with this invention could include a primary in6ulated storage tank having a vapor space, a first conduit communicating with the primary storage tank and having means for ~ ic~ting with a vehicle fuel tank, the first conduit including a pump for withdrawing and yLe6DuLizing liquefied cyrogenic fuel; and a second conduit ~ ;rating with the vapor space in the primary storage tank and with the first conduit dn..l-nLLaam of the pump, the second ~ WO96/01391 21 ~4223 r~ sl ~c conduit ;nclll~ing a , ~ssor for increasing the ~LasauL~ of cryogenic fuel from the vapor space and feeding it to the first conduit for mixture with the pressurized liquefied cryogenic fuel and onto the vehicle fuel tank.
The liguefied cryogenic fuel in the primary insulated storage tank desirably is at about 5 psig to 150 psig and a tl _ aLULe of about -252~F
to -186~F.

0 ~T~ DE~ OF T~E . r Figure 1 diayL tically illustrates a first ~ L of ~yaLa-u~ useful in practicing the invention;
Figure 2 diagrammatically illustrates a second Dmho~i- L of apparatus useful in practicing the invention;
Figure 3 diagrammatically illustrates a third ' 'i- L of apparatus useful in practicing the invention.
Figure 4 diagrammatically illustrates a fourth ~mho~i- L of apparatus useful in practicing the invention;
Figure 5 diagrammatically illustrates a heat oY~hAng~r, gas reservoir, and by-pass conduit, useful in practicing the invention;
Figure 6 illustrates a manifold heat exchanger useful in practicing the invention; and Figure 7 diagrammatically illustrates an o~i- t of a fueling station useful for practicing the invention.

WO96101391 2 ~ q 4 2 2 3 1~"~ ~ ~

n~T~TT~n V~ OF T~ n ~

To the extent it is ro~crnAh]e and practical the same or similar elements which appear in the various drawing figures will be illustrated by the same numbers. As used herein, the term "cryogenic fuel" inrlll~oc natural gas, methane, et_ane, ethylene, and hYdLU~en. For c; l;r;ty, the following ~otAilo~ description refers to natural gas only, but it should be understood that other cryogenic fuels may be used in the invention as well.
With reference to Figure 1, which illustrates a first ~ nt of the invention, the insulated primary tank 10 is constructed of suitable material so as to safely store a volume of liquefied natural gas or methane 12 at a relatively low es~uLe, for example at about 5 psig to 150 psig and corrosrnn~ 1 ng saturation temperature of about -252~F to -186~F. A vapor space 14 in the upper part of primary tank 10 is provided so as to ~ te vapor 16 which forms as a result of heat flow from the ~ re into the tank. Conduit 18 communicates with the interior of tank 10 and provides a means for filling the tank with liquefied natural gas.
Conduit 20 communicates with the lower interior space of tank 12 and with heat oYrh~ngor 36. Pump 22 is located in conduit 20. Conduit 20 thus provides _ means for withdrawing a stream of liquefied natural gas from primary tank 10 and feeding it to the heat oYrh~ngor 36. The pump 22 may require a minimum circulation rate at all times.
When not fueling vehicles, valves 71 and 72, du..ll~LLeam of pump 22, are closed and the liquefied ~ WO96/01391 2 1 9 ~ 2 2 3 F~~

natural gas is forced to flow back to primary tank 10 through conduit 19. When the ~ LL am fueling valve 71 is open, for example, flow through conduit 21 is restricted by an orifice 21 or other similar flow restricting device so that most of the flow is forced downstream of conduit 19.
Natural gas vapor which A~- 1 Ates in vapor space 16 is optionally, but not nDr~ccAnily, withdrawn th~efL~. through conduit 26 which communicates with the vapor space and with conduit 20 uy~LLea~ of the heat exchanger 36 but ~ LLeam of pump 22. Vapor pump or ~ ~ssor 29 is provided in conduit 26 to increase the ~L~S~UL~ of the vapor fed to conduit 20 and check valve 27 prevents fluid flow back into vapor space 16. By b~ ~n~; ng the vapor stream from conduit 26 into admixture with the liquefied natural gas stream in conduit 20 the vapor is con~ncP~ and the liquid is warmed slightly.
The liquefied natural gas stream is then delivered by conduit 20 to conduit 28 which icAte5 with and feeds the liquid to conduit 32. Conduit 28 includes a restriction device 33 through which the flow rate of liquid c~n be measured by a flow control}er 31. Flow controller 31 permits a portion of the liquefied natural gas stream through conduit 28 to bypass the heat exchanger for mixture with warmed natural gas exiting the heat exchanger 36 and thereby controls the approximate flow rate through the restriction device 33. Temperature controller 39 permits an amount of warmed natural gas in conduit 38 to mix with cold liquid in conduit 34 in desired proportions to attain desired temperature for delivery to conduit 66. The liquefied natural gas 21 ~4~23 iB fed from conduit 32 into the inlet side of heat pYrhAn~r 36.
Further, as liquefied natural gas flows through the heat PYrh~ngPr 36, its temperature may be raised to any desirable level, including that which vaporizes the liquid, so long as the mixed t., _LuLe in conduit 66 may approach a subcooled or saturated condition, such as to about -238~F to -126~F at a euLL~~ ng ~r eOoULe of about 20 psig to 550 psig. The heat needed to raise the tempera-ture of the liquefied natural gas can be indirectly supplied by ambient or heated air or water, or any other suitable heat êxchange fluid, which can be fed to the heat PYrh~ngor at a flow rate which will raise the liquefied natural gas temperature to the extent desired, eliminating the need for bypass conduit 34.
The warmed liquefied natural gas is withdrawn from the heat exchanger 36 by conduit 38 and is fed to conduit 66. The combined streams of liquefied natural gas from conduits 34 and 38 are fed to conduit 66, the end of which is in temporary and removable _ ;cation with insulated vehicle fuel tank 42 located at the rear of bus 44 via hose 73 and ~;~cu~,PcLable coupling 74. When connected, the pressure in vehicle fuel tank 42 equates with the ~LeSoULè in hose 73. The warmed liquefied natural gas is fed from conduit 66 into insulated fuel tank 42 until the tank 42 is essentially filled. Valve 71 is then closed, and the hose 73 and coupling 74 are removed from vehicle fuel tank 42 and the tank 42 is capped.
Conduit 41 ~ irates upstream with conduit 38 and downstream with the primary storage tank 10. Alternatively, it may ~_ icate upstream ~WO96/01391 P~ . r~ -2~ 94223 with the mixed fluid conduit 66. In either configuration, conduit 41 ;nrlllAP~ a back p~es-u regulator 43 which opens wllen yL~s_uLe in primary storage tank 10 drops below the setpoint of regulator 43. In this mam~er, the ~L~UL~ in primary tank 10 can be maintained above a minimum Ul ~ with the output of heat exchanger 36. The operation of e~o~ 29 is unaffected and is still useful to maintain the pL es~ur e in primary tank 10 below a maximum value.
Alternatively, regulator 43 can be replaced by a valve (not illustrated) which opens in response to a pressure switch sensing a drop in pressure in primary tank 10.
Moving d~ L,_am, conduit 66 includes valve 71 for controlling the flow of liquefied natural gas. Conduit 75 communicates with conduit 66 ~ D~L~am of valve 71 and with the primary storage tank 10. Conduit 75 includes valve 72.
Both valves 71 and 72 are activated by a P~S~UL~
switch 70. When hose 73 is connected to a vehicle fuel tank 42, pressure switch 70 senses whether the es~uL~ in the hose 73 (which is equal to the p~esDuL~ in the vehicle fuel tank) is higher than a predetPrminPd set point. If so, valve 72 is opened and valve 71 remains closed. This interaction enables high ~L~ur~ fluid in the vehicle fuel tank to flow through conduit 75 to the primary storage tank 10. If, on the other hand, the ~Les~u~e in hose 73 is below the predetPrminpd set point of ~L~S uLe switch 70, then valve 72 remains closed and valve 71 opens to permit liquefied natural gas to flow through conduit 66 into the vehicle fuel tank 42.

Wo96/01391 2~ 942?3 - P~

Alternatively, the ~L~S~UL ~ switch 70 can be replaced by an inlet pLas~uLa regulator (not illustrated~ located ~ " LL~;U of valve 72 in line 75. The ~l~ssuLa regulator senses hose 73 ~Las~uLa when valve 72 is opened in a timed se~u~ e with valve 71 initially closed. After a preset period of time has elapsed and fluid from vehicle fuel tank 42 i6 fed to conduit 75, valve 72 i8 closed and valve 71 i8 opened to permit liquefied natural gas to flow from conduit 66 to vehicle fuel tank 42.
To m;n;m;7e the operating ~L~S_UL~
fluctuations in primary tank lO, conduit 75 preferably enters the bottom of the primary tank 10 so that the warmer, higher p as~uLa fluid from vehicle fuel tank 42 is absorbed by the liquid rather than the vapor contents of the tank. In particular, the elevation of the outlet of conduit 75 is preferably spaced above and laterally apart from the entrance of conduit 20, to m;n;m; 7e the possibility that any vapor in conduit 75 becomes entrained in conduit 20 and upsets a pump or the process.
Pigure 2 illustrates another ~ t of the invention. It will be readily seen that this embodiment incorporates the primary tank lO and heat PY~hAngnr 86 as well as many of the conduits, pump 22 and a~soL 29 forming part of the first : ~o~; ~ shown in Figure 1.
Conduit 28 _ ;cntes with flow controller 31 and conduit 32 which _ ;cates with heat PY~hAngPr 36 and serves to feed a stream of cold liquefiea natural gas from the flow controller 31 to the heat PYrhAngnr 36 in which the liquefied natural gas is warmed and subsequently fed therefrom ~ W096~1391 . .~

into conduit 38 which feeds the stream of liquefied natural gas to conduit 40.
Conduit 34 also ;nates with flow controller 31 and with conduit 40. Conduit 34 provides a means for feeding cold liquefied natural gas around or past the heat ~Y~h~nqQm 36 and into admixture with the liquefied natural gas fed by con-duit 38 to conduit 40. I~ aLuLe controller 39 and control valve 37 provide a system by which the t~ , aLuLe and inherently the p~ ULe of the liquefied natural gas fed by conduit 40 to insulated ~;~pPn~;nq tank 50 can be controlled. Thus, t~ , a~uLe controller 39 L~u--ds to the t~ , G~ULe of the liquefied natural gas 52 in conduit 40 and by signal means actuates control valve 37 so that liquefied natural gas fed by conduit 38 to the control valve 37 is proportioned with liquefied natural gas 52 from conduit 34.
Under a~ru~Liate circumstances the flow through conduit 32 could be from 0 to 100% of the flow in conduit 28, and the flow through conduit 34 could be from 0 to 100% of the flow in conduit 28.
Liquefied natural gas 12 i6 stored in ~;~p~n~;ng tank 50 in a saturated condition at a temperature of about -238~F to -126~F and a CULL:-lJO~'~;ng pressure of about 20 psig to 550 psig.
Vapor 54 which accumulates in the upper interior space of dispensing tank 50 is withdrawn through conduit 56 and is returned to the interior of primary storage tank 10. Pressure relief valve 58 in conduit 56 is set to open at a predet~rm;nP~
higher vapor pressure than the pressure normally present in the vapor space of the dispensing tank 50.

WO96/01391 2 1 9 ~ 2 2 3 As stated above, with respect to Figure 1, vehicle fuel tank 42 may develop high intorn~l yLeSDUL~ such that the fueling operation may be h:, ~d or even prevented. ~o relieve plesauLe in vehicle fuel tank 42 in the configuration illustrated in Figures 2 and 3 with a dispensing tank 50, the high pL~SDULe fluid from vehicle fuel tank 42 is ~eLuL..ed to iiRp~n~ing tank 50 in order to avoid mixing warm fluid with the cold liquefied natural gas in the primary bulk storage tank 10.
When dispensing tank 50 is being filled via mix fluid conduit 40 and the pres6ure in disp~n~ing tank 50 is undesirably high, relatively cold liquefied natural gas may be sprayed into the vapor space 54 to reduce ~LesauLe. To accomplish this result, conduit 23 communicates with conduit 20 and with the vapor space 54. Conduit 23 in~ a back pLeDDUle regulator 25 and a check valve 27.
Regulator 25 opens when the ~Le5auLe in dispensing tank 50 exceeds a predet~mm;n~d set point. When the pL~ aUL~ in ~;~p~n~ing tank 50 rises above the setpoint, regulator 25 opens and cold liquefied natural gas is sprayed into the vapor space 54 until the ~LesauLe is maintained below the predet~rm;n~d maximum ~leSauLe setpoint.
The setpoint of regulator 25 is preferably below the setpoint of the regulator 58 in conduit 56, when present. For example, for a system which is designed to r ;n~lly deliver -200~F liquid methane (for which the saturation pressure is 100.6 psig), the setpoint of regulator 25 may be 115 psig and the setpoint of regulator 58 may be 125 psig.
In operation, regulator 25 will open before regulator 58. If pump 22 is running, then cold liquid will flow through conduit 23 into dispensing ~ WO96/01391 2 1 ~ ~ 2 2 3 P~

tank 50 and lower the pLeS~uLe in dispensing tank 50. If pump 22 is not rumling, there will be no flow in conduit 23 and the ~l~sDuLe in tank 50 will continue to rise due to ambient or other heat gain until regulator 58 opens.
In an alternate ~ L (not illustrated), the regulator 25 can be replaced by a valve that opens in response to a switch that senses the pLeSDUL~ in the dispensing tank 50.
Conduit 80 communicates u~DLLeam with the lower interior space of dispensing tank 50. The dc....DLlaam end of conduit 80 communicates with conduit 66, and conduit 80 ~ncll-~P~ a pump 82 that withdraws liquefied natural gas from ~i~pPn~ing tank 50 and feeds it to conduit 66. Pump 82 may require a minimum circulation rate to avoid priming difficulties. Thus, when valve 71 is closed a minimal amount of liquefied natural gas recirculates to dispensing tank 50 via conduit 81. A flow restricting device such as an orifice is positioned in conduit 81 to allow flow through conduit 81 when valve 71 is closed but restricts flow through conduit 81 when valve 71 i6 open.
The d... DLLea~ end of conduit 66 is provided with a hose 73 having a coupling 74 which can be removably connected to the outer end of fuel fill pipe 76 which communicates with the vehicle fuel tank 42. Liquefied natural gas at a temperature of about -238~F to -126~F and a pressure of about 20 psig to 550 psig can be withdrawn from dispensing tank 50 by means of conduit 80 by the pump 82 and fed through conduit 66 and to hose 73 which feeds the fuel into vehicle fuel tank 42 at such time as the bus 44 is to be refueled. After the fuel tank 42 is filled, the hose 73 is uncoupled WO96/01391 ~ 94223 r ~

from pipe 76 and the end of pipe 76 is sealed by a cap, not shown.
The apparatus illustrated in Figure 3 also permits an optional way to practice the invention.
Thus, by means of conduit 64 relatively cold liquefied natural gas withdrawn from primary tank lO
can be fed into admixture in control valve 62 with the warmer liquefied natural gas supplied by conduit 60 to form a blend which can then be fed into vehicle fuel tank 42 at a t aLule lower than the t~ ~Lu-e of the liquid in the dispensing tank 50.
In this manner the ~Les~uLe in the dispensing tank 50 may be kept higher than the vehicle fuel tank ~L~S~UL~ in order to provide the motive force nPc~C~Ary for ~;cponc;ng the liquefied fuel and eliminate the need for pump 82. This is also desirable, at times, to ~ ~~te for the warming effect exerted by a substantially unused fuel tank 42 and also the heat which enters the fuel during the filling operation due to vapor c~nd~nc~tion.
Liquefied natural gas exiting the control valve 62 is fed to conduit 66. The temperature of the liquefied natural gas stream flowing through conduit 66 is measured by temperature controller 68 which sends a signal to control valve 62 to properly . proportion the amount of liquefied natural gas from conduit 60 and conduit 64 which is fed through the control valve 62. The amount of liquefied natural gas flowing through conduit 66 can be 0% to 100%
from conduit 60 and 0~ to 100% from conduit 64 der~n~; ng on existing conditions.
The apparatus illustrated by Figure 4 is very similar to that shown in Figure l. However, the apparatus of Figure 4 does not include the ~ WO96101391 2 1 9 4 2 2 ~

indirect heat eY~hAnq~r 36 forming part of the ~Lus illustrated in Figures 1 through 3.
Nith reference to Figure 4, the natural gas vapor which ~~_ lAtes in vapor space 16 is withdrawn therefrom through conduit 26 and fed to conduit 28 which feeds it to conduit 32 through a flow controller 31. The liquefied natural gas stream is delivered by conduit 28 where the vapor from conduit 26 is cnn~Dn~d by direct contact with the liquefied natural gas which is thereby warmed.
The warmed liquefied natural gas stream is fed from control valve 30 to conduit 66 and by it to hose 73 for delivery to vehicle tank 42. The flow rate of the liquefied natural gas fed through conduit 66 i5 controlled by flow controller 31 which regulates control valve 30. The amount of liquefied natural gas fed to conduit 38 relative to vapor supplied by conduit 26 regulates the temperature in conduit 32 and is controlled by the duration of _ , eSD~L 29 operation.
Illustrated in Figure 5 is an alternate ~ ' ';r ~ of an apparatus for developing a mixed stream of warmed and ~L~sDuLized liquefied natural gas for storage in dispensing tank 50 or direct feeding to vehicle fuel tank 42. Conduit 28 feeds ~L~s~uLized liquefied natural gas 12 from pump 22 to the heat exchanger 36 and to conduit 34. Heat exchanger 36 is of sufficient thermal capacity to ensure the liquid entering the heat PY~hAnqor 32 boils to become natural gas and that the outlet temperature approaches that of the heat source. For example, if heat PYnh~nq~r 36 is a natural air draft finned tube heat exchanger, then the outlet t~ ~ ~LUL~ of the gas in line 91 should be close to W096/01391 r~.~ h ambient t- _ ~LULe with an approximately known enthalpy for a given pLas~uLe.
Reservoir 92 is located on the discharge of heat exchanger 36 and is of sufflcient size that rapid changes in discharge from reservoir 92 do not appreciably affect the pL~aaULe within reservoir 92.
The pLebaULe in reservoir 92 i6 ~-intAinPd by pL~uLe controller 95 regulating the valve 94 which restricts flow into heat PynhAngPr 36. The liquid flow rate in liquid conduit 34 is controlled by flow controller 97 and regulating valve 96. The temperature in outlet conduit 40 is controlled directly by t~ , ~LuLe controller 99 regulating the gas flow valve 98 included in vapor conduit 93.
In particular, it is desirable that the ~bsolute ~Ies_uLe in vessel 92 be approximately 50%
greater than the absolute ~LeS~uL~ in conduit 40 so that the flow in valve 98 approaches a choked flow condition. In this manner the mass flow in vapor conduit 93 is essentially predetPrm;nPd for a given position of valve 98.
Figure 6 illustrates a particular heat ~YrhAngPr 36 configuration having a cnntinllnl~c horizontal bottom inlet and a horizontal top outlet manifold for use in the present invention as opposed to a conventional serpentine tube configuration.
Conduits 32 and 38 serve essentially the same functions as described above with respect to Figures l, 2 and 3 in addition to acting as the horizontal manifolds in the illustrated heat oYnhAngPr~ Cold liquid is fed by pump 22 to line 32 and under steady conditions estAhli~hP~ a boiling liquid level in the vertical tubes of the heat exchanger 36. When tank 42 or 50 has been filled and the transfer process is complete, valve 37 closes and some residual liguid ~W096,0l3gl 2 1 9 ~ 2 2 3 T~

remains in the bottom manifold 32 and in the lower portions of the vertical tubes. This residual liquid will cnntiml~ to absorb heat from the environment causing it to ev~Lnte in part.
Because valve 37 is closed, ~LessuLe in the heat rYrhAng~r 36 will rise allowing some liquid to be pushed out of the bottom manifold 32 and back u~aLLe~ toward primary tank 10. Once the heat ~Yrh~ng~r 36 has been ~drained" of liquid in this manner, the t~ ~LuLè of the vapor trapped within the heat ~YnhAng~r 36 will approach ambient temperature and further heat gain to the system will be min;mi7~.
Figure 7 illustrates the present invention with a number of dispensing stations. The flow rate to each vehicle need not be exactly the same but should be approximately equal because it is desirable to employ one or two large capacity pumps in the system rather than many small capacity pumps (each dedicated to a single vehicle) in order to min~mi7e capital costs and wear on the pumps due to frequent starts. Thus, an e~~~ ic~l means to regulate the flow from one or two pumps to a number of different vehicles is desirable. This can be accomplished by regulating the flow through each hose at a fueling station in response to a pLeSaULe drop induced by a flow res1:riction upstream of each hose. There will be a nominal ~LasauLe drop associated with normal flow rate. Observed ~Le8~uLe drops greater than or less than the nominal ~LeSDUL~
drop will indicate flows greater than or less than the nominal flow rate, respectively.
As shown in Figure 7, conduits 66 and 75 remain essentially the same as shown in Figures 1 through 4 except that they are now branched to serve wo r/0139~ J~

each of the three stations equally. Item nos. 42, 70, 71, 72, 73 and 74 are now shown in triplicate with a suffix 1, 2 or 3 for each respective ~;~p~n~inq station. All of these items serve essentially the same function at each station.
A flow restrictor 781 is included in conduit 661 u~aLL~a~ of regulator 711 and hose 731.
A spring-actuated differential ~L~5 UL~ regulator 791 with an external spring chamber connection, modulates its opening position in response to the differential ~Les~uLe which occurs across restrictor 781. Regulator 791 tends to close and restrict flow if an Ahn~rr-lly high flow across restrictor 781 induces a ~Le~DuLe drop above the setpoint of regulator 791. ~he higher initial flow rate may occur if the pLe~uLe in vehicle fuel tank 421 is abnormally low. Differential ~Le8DuLe regulator 791 can be a unit such as the 95 Series or 98 Series sold by Fisher Controls company of Marshalltown, Iowa. Duplicative regulators 792, 793 and restrictors 782, 783 are shown for hoses 732, 733, respectively. Further, flow restrictors 781, 782 and 783 can be either u~L.~a~ or downstream of their respective regulators 791, 792 and 793, ~r~n~;nq on the regulator's design.
Regulators 791, 792 and 793 can be gage ~lea~uL~ regulators (as opposed to differential pressure regulators~ if the supply ples~uL~ is relatively fixed; i.e. the flow restrictor can be upstream of an inlet ~L~s~uLa regulator. ~owever, the use of a differential ~Le6auLe regulator as illustrated in Figure 7 is preferred because it operates essentially ;n~rPn~ntly of supply 1~1 e~jUL t: .

~ ~096/01391 2 1 9 4223 r~ n In the subsequent examples the composition of LNG has been assumed to be essentially 100 methane to simplify the determination of th. yll~ic points.

I!:~AMPLIS 1 A transit bus 44 stores liquefied natural gas on-board in an insulated vehicle tank 42. Fuel is removed from the vehicle tank and fed to a fuel injected internal combustion engine. Proper operation of the engine requires a ~L~S~UL~ of 100 psig in the vehicle tank (the ~ULL~ n ling saturation t -~LUL~ is approximately -Z00~F).
At the bus fuel filling station, liquefied natural gas is stored in a large bulk storage or primary tank 10 at 30 psig (its cu-L-h~u~;ng saturation t~ ~LuLa is approximately -231~F). If the vehicle tank 42 is filled with -231~F liquid directly from the bulk storage tank, the pressure in the vehicle tank 42 will drop significantly below 100 psig, and the bus engine will not properly operate.
The bus 44 has been parked for some time, and heat transfer from the ai ~ e has caused the liquefied natural gas in the tank 42 to warm from -200~F to -194~F and the tank ~L~S~UL~ to rise from about 100 psig to about 120 psig.
In one example of the ~ ' ';r-nt shown in Figure 1, liquefied natural gas is withdrawn from the bulk storage or primary tank 10 by means of conduit 20 at the saturation t~ ~LuLa of -231~F
and is increased in ~Las~uLe by pump 22 to 140 psig.
From pump 22 the cold stream flows through conduits 20, 28 and 32. If ~ assuL 29 is running, the WO96/01391 ~1 ~4~

cold liquefied natural gas stream cond~n~cc excess vapor from tank 10 supplied by conduit 26 to conduit 20 and then flows into heat PYrhAngPr 36, wherein it is heated in a controlled manner such that the mixed outlet t~ LUL~ in conduit 66 is -200~F. The liquefied natural gas supply ples~uLe of 140 psig ~V~L- - the vehicle tank back ~Lesaur~ of 120 psig, plus the ~LessuL~ drop in heat P~nh~ng~r 36 and conduits 20, 38, and 66 in order to establish flow to the vehicle tank. If the vehicle fuel tank 42 back p~es_uLe is excessive, it will first be vented back to primary tank 10 through conduit 75.
Further, ~L~S~ULe regulator 33 has a setpoint of 20 psig and if the ~Las~uLe in primary tank 10 drops below 20 psig as sensed by yL~auL~ regulator 33, the ~es~uL~ will be raised by the introduction of warmed and pressurized liquefied natural gas via conduit 41. The bus vehicle tank is thus filled with -200~F liquefied natural gas and it maintains an operating pressure of near 100 psig at the conclusion of the filling seguence, allowing the bus engine to be started and the bus driven away.

~Y~MPLF 2 As illustrated in Figure 2, a quantity of liquid naturAl gas has been previously removed from primary tank 10 via pump 22, heated in a controlled manner to -200~F via line 28, heat PYrh~nger 36, and t ~LuLe controller 39, and stored in ~;Cponcing vessel 50.
The setpoint of yres~uL~ regulator 25 is 107 psig (the corrpcpnnd;ng saturation temperature is -198~F). If the ~es_uLe in dispensing tank 50 exceeds 107 psig while d;cpPnc;ng tank 50 is being ~ W0 961013gl 2 1 9 4 2 2 3 P~

filled because of ambient heat transfer or the latent heat duty of vapor ~ n~ation within the tank, then regulator 25 opens and allows cold liquid to enter d;~pPn~ing tank 50 and thereby limits the plesnuLe in di~p~n~ing tank 50 to 107 psig.
Therefore, the temperature of the liquid in dispensing tank 50 will be within the controlled t~ ~tUL~ range of -200~F feed t~ ~LUL~ and the -198~F saturation temperature at 107 psig.
Regulator 43 limits the minimum pLeSnULe in primary tank 10. The setpoint of pL~6nULe regulator 43 is 20 psig. If the ~,~snuL~ in primary tank 10 drops from 30 psig to less than 20 psig as liquid is removed from it, then regulator 43 opens in order to maintain the pLesnuLe in primary tank 10 to at least 20 psig.
Conversely, _ LeS5~L 29 limits the maximum pL 56UL e in primary tank 10 and is typically most advantageous during periods of low facility use. The setpoint to start operation of ~85~1 29 is 70 psig. If when vessel 50 is being filled with liquid the plesnuLe in primary tank 10 is 70 psig or higher, then ~SSOl 29 runs in order to withdraw vapor from primary tank 10 and auto refrigerate is contents.
rOn~ r the scenario wherein the dispensing ~pLJdL~Lus of Figure 2 is unused for an extended period of time before a bus arrives to be filled. ~ ,'~ric heat gain into dispensing tank 50 will cause its te~L~LuLe to rise. The setpoint of pressure regulator 58 is 120 psig (the cuLL~ ing saturation temperature is -194~F).
When its temperature exceeds -194~F, its c~LL~L..I~ding saturation pLeS~uLe will exceed 120 psig, and regulator 58 will open to restrict the W 096/01391 2 1 9422~ Pc~rluS95103300 pLas~iuLa in d;~pon~ing tank 50 to 120 psig and the liquid t~ tuLa to -194~F. In this scenario regulator 25 will have opened, but no flow from line 23 will have entered tank 50 because pump 22 is stopped.
Now consider that the bus 44 arrives to be filled with LNG shortly after dispensing tank 50 has been filled. The bus 44 has just returned from regular operation and the p~asauLa in vehicle fuel tank 42 is 100 psig. The pressure in tlicponF:;ng tank 50 is 107 psig and the t~ ~lLuLe: of the liquid 52 in tank 50 is -198~F. Pump 82 is running and liquid is flowing through the recircll1At;nn conduit 81 but valve 71 is closed and there is no flow in conduit 66. Valve 72 i5 also closed. The maximum differential pLJ5~:iULa developed by pump 82 is 40 psi. Hose 73 is then rnnnortecl to vehicle fuel tank 42 via c~mnPctAhle coupling 74, whereupon the pLeaDULt! in hose 73 equates with the p~ aU~e in vehicle fuel tank 42 of 100 psig. The pL~a~iuL~
switch 70 haB a setpoint of 120 psig. Since the yLta~uLa which is sensed (100 psig) i6 less than the ~witch 70 setpoint (120 psig), valve 71 is open and valve 72 is closed. LNG at -198~F and 105 + 40 = 145 p5ig (less frictional losses) flows immediately through line 66 into vehicle fuel tank 42.
r~nc;~O~ again that the bus arrives to be filled shortly after A;cronc;ng tank 50 has been filled, but instead that the bus 44 had been parked for an extended period of time. ~ -_ '~riC heat gain to vehicle fuel tank 42 caused the liquid within the vehicle fuel tank 42 to increase in t~ c. LUL a to -18 6~ F, and the yL a6a UL e: in vehicle fuel tank 42 C~rL ea~unds to the saturation pLesauLa ~ WO96/01391 2 19 ~ 2 2 ~ r .,~

of 150 psig. Pressure switch 70 will 6ense a pL~5DULe tl50 psig) higher than its setpoint (120 psig) when hose 73 is connPcted to dispensing tank 42. In this case, valve 72 will open (valve 71 will remain closed) and vapor wi.ll flow ~rom vehicle fuel tank 42 to ~;Cp~ncing tank 50 for such time until the pLeS uLa in vehicle fuel tank 42 drops to the switch setpoint (120 psig),, whereupon valve 72 will close and valve 71 will open allowing LNG to flow into vehicle fuel tank 42 ~rom dispensing tank 50.
The LNG in dispensing tank 50 will have been warmed slightly by the addition o~ the gas from conduit 75 but this is not disadvantageous for infrequent OC~;uL L e~ es.

r~YPLD 3 In one example of the embodiment shown in Figure 3, liquefied natural gas is withdrawn from the bulk storage tank 10 at the saturation t~ tUL~ of -231~F and at 30 psig and increased in p~esDuL~ by pump 22 to 140 psig. The subcooled liquefied natural gac ~ c excess vapor from tank 10 flowing in conduit 26 in conduit 20. The liquefied natural gas flows by means of conduits 28 . and 32 into heat ~Yrh~ng~r 36 wherein it is heated in a controlled manner in conduit 40 to near its saturation temperature of -189~F, such that vapor and liquid are in saturation equilibrium at 140 psig in vessel 50. Warm liquefied natural gas at 140 psig and about -189~F in conduit 60 is mixed with - 30 cold liquefied natural gas at 140 psig and -231~F
from conduit 64 in control valve 62 to produce liquefied natural gas at 140 psig and -200~F. When dispensing tank pLeS-ULe is excessively high, as W096/01391 21 q4223 sensed by regulator 25, cold ~L~DuLized liquefied natural gas is sprayed into vapor space 50 via conduit 23. High ple6auLe fluid from vehicle fuel tank 42 is fed to dispensing tank 50. The liquefied natural gas supply ~LeS~UL~ Or liO psig uv~lC
the vehicle tank back p~es~uL~ of 120 psig plus the yles~uu~ drop due to conduits 60,64 to establish flow, so that the bus can be filled with -200~F
liquefied natural gas while maintaining an operating 0 ~L~S~ULe near 100 psig, permitting the bus to be driven away.

Claims

WHAT IS CLAIMED IS:

1. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the primary storage tank and with the heat exchanger, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary storage tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it to the heat exchanger wherein the pressurized liquefied cryogenic fuel is warmed to a subcooled or near saturated condition; and (d) a second conduit communicating with the heat exchanger and having means for communicating with a vehicle fuel tank, the second conduit for receiving warmed and pressurized liquefied cryogenic fuel from the heat exchanger and feeding it to a vehicle fuel tank for storage as a liquid therein at an approximate saturated condition.

2. The apparatus of claim 1 and further comprising:
(a) a third conduit communicating with the primary tank and having means for communicating with a vehicle fuel tank, the third conduit for receiving fluid from the vehicle fuel tank and feeding it to the primary tank to reduce the internal pressure of the vehicle fuel tank.

3. The apparatus of claim 1 and further comprising:
(a) a third conduit communicating with the heat exchanger and the primary tank, the third conduit for receiving the warmed and pressurized liquefied cryogenic fuel from the heat exchanger and feeding it to the primary tank to maintain the pressure in the primary tank above a predetermined minimum pressure.

4. The apparatus of claim 1 in which the heat exchanger is a vertical tube ambient heat exchanger comprising a continuous horizontal bottom inlet and a continuous horizontal top outlet manifold.

5. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the primary tank and with the heat exchanger, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it through a control valve to the heat exchanger wherein the pressurized liquefied cryogenic fuel is converted to pressurized cryogenic fuel vapor at a temperature approaching that of a heat source for the heat exchanger;
(d) a reservoir in vapor communication with said heat exchanger for receiving and storing warmed and pressurized cryogenic fuel vapor;

(e) a second conduit having means for transferring warmed and pressurized liquefied cryogenic fuel to a vehicle fuel tank at a subcooled or near saturated condition;
(f) a liquid conduit communicating with the first conduit downstream of the pump and with the second conduit, the liquid conduit including a control valve for receiving and controlling the flow of pressurized liquefied cryogenic fuel from the first conduit to the second conduit; and (g) a vapor conduit communicating with the reservoir and the second conduit, the vapor conduit including a control valve for controlling the flow of warmed and pressurized cryogenic fuel from the reservoir to the second conduit for mixture with the pressurized liquefied cryogenic fuel to form a warmed and pressurized liquefied cryogenic fuel in the second conduit at an approximate saturated condition.

6. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the liquefied cryogenic fuel in the primary tank and with the heat exchanger, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it to the heat exchanger wherein the pressurized liquefied cryogenic fuel is warmed to a subcooled or near saturated condition;

(d) a second conduit communicating with the heat exchanger and having means for communicating with a vehicle fuel tank, the second conduit including a flow restrictor for controlling the flow of warmed and pressurized liquefied cryogenic fuel from the heat exchanger to a vehicle fuel tank for storage therein as a liquid therein at a subcooled or an approximate saturated condition;
and (e) a regulator having means for sensing fluid flow pressure drop across the flow restrictor and means for reducing the flow of warmed and pressurized liquefied cryogenic fuel to a vehicle fuel tank in response to high fluid flow pressure drop in the restrictor.

7. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the primary storage tank and with the heat exchanger, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary storage tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it to the heat exchanger wherein the pressurized liquefied cryogenic fuel is warmed;
(d) a stationary cryogenic fuel dispensing tank;
(e) a second conduit for feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to the stationary dispensing tank for storage in the dispensing tank at an approximate saturated condition; and (f) a third conduit communicating with the dispensing tank and having means for communicating with a vehicle fuel tank, the third conduit for receiving warmed and pressurized liquefied cryogenic fuel from the dispensing tank and feeding it to a vehicle fuel tank for storage therein at an approximate saturated condition.

8. The apparatus of claim 7 in which the third conduit includes a pump.

9. The apparatus of claim 7 in which the third conduit includes a temperature control valve and the apparatus further comprises:
(a) a fourth conduit in communication with the first conduit downstream of the pump and with the temperature control valve, the fourth conduit for receiving pressurized liquefied cryogenic fuel from the first conduit and feeding it to the temperature control valve for mixture with warmed and pressurized liquefied cryogenic fuel in the third conduit.

10. The apparatus of claim 7 and further comprising:
(a) a fourth conduit communicating with the primary tank and having means for communicating with the vehicle fuel tank, the fourth conduit for receiving fluid from the vehicle fuel tank and returning it to the primary tank to reduce the internal pressure of the vehicle fuel tank.

11. The apparatus of claim 7 and further comprising:
(a) a fourth conduit communicating with the primary tank and having means for communicating with the vehicle fuel tank and returning it to the dispensing tank to reduce the internal pressure of the vehicle fuel tank.

12. The apparatus of claim 7 and further comprising:
(a) a fourth conduit communicating with the heat exchanger and the primary insulated tank, the fourth conduit for receiving the warmed and pressurized liquefied cryogenic fuel from the heat exchanger and feeding it to the primary insulated tank as needed for maintaining the pressure in the primary storage tank above a predetermined minimum pressure.

13. The apparatus of claim 7 and further comprising:
(a) a fourth conduit communicating with the first conduit downstream of the pump and with the dispensing tank, the fourth conduit for receiving pressurized liquefied cryogenic fuel from the first conduit and feeding it to the dispensing tank to maintain the pressure in the dispensing tank below a predetermined maximum pressure.

14. The apparatus of claim 7 in which the heat exchanger is a vertical tube ambient heat exchanger comprising a continuous horizontal bottom inlet manifold and a continuous horizontal top inlet manifold.

15. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the primary tank and with the heat exchanger, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it through a control valve to the heat exchanger wherein the pressurized liquefied cryogenic fuel is converted to pressurized and vaporized cryogenic fuel near at a temperature approaching that of a heat source for the heat exchanger;
(d) a reservoir in vapor communication with the heat exchanger having means for receiving and storing pressurized and cryogenic fuel vapor from the heat exchanger;
(e) stationary insulated dispensing tank having means for receiving and storing warmed and pressurized liquefied cryogenic fuel at an approximate saturated condition;
(f) a liquid conduit communicating with the first conduit downstream from the pump and with the dispensing tank, the liquid conduit including a control valve for receiving and controlling the flow of pressurized liquefied cryogenic fuel from the first conduit to the dispensing tank;
(g) a vapor conduit communicating with the reservoir and the dispensing tank, the vapor conduit including a control valve for controlling the flow of pressurized and vaporized cryogenic fuel from the reservoir to the dispensing tank for mixture with pressurized liquefied cryogenic fuel to form a pressurized liquefied cryogenic fuel at an approximate saturated condition; and (h) a second conduit communicating with the dispensing tank and having means for feeding warmed and pressurized liquefied cryogenic fuel from the dispensing tank to a vehicle fuel tank.

16. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point;
(b) a heat exchanger;
(c) a first conduit communicating with the primary storage tank and with the heat exchanger the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary storage tank, increasing the pressure of the withdrawn liquefied cryogenic fuel and feeding it to the heat exchanger wherein the pressurized liquefied cryogenic fuel is warmed;
(d) a stationary cryogenic fuel dispensing tank;
(e) a second conduit for feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to the stationary dispensing tank for storage in the dispensing tank at an approximate saturated condition;
(f) a third conduit communicating with the dispensing tank and having means for communicating with a vehicle fuel tank, the third conduit including a flow restrictor for controlling the flow of warmed and pressurized liquefied cryogenic fuel from the dispensing tank and feeding it to a vehicle fuel tank for storage therein at an approximate saturated condition; and (g) a regulator having means for sensing fluid flow pressure drop across the flow restrictor and means for reducing the flow of warmed and pressurized liquefied cryogenic fuel to a vehicle fuel tank in response to excessively high fluid flow drop in the restrictor.

17. Apparatus comprising:
(a) a primary insulated storage tank containing liquefied cryogenic fuel at a low pressure and at a temperature close to its boiling point and including a vapor space containing cryogenic fuel;
(b) a first conduit communicating with the primary storage tank and having means for communicating with a vehicle fuel tank, the first conduit including a pump for withdrawing liquefied cryogenic fuel from the primary storage tank, increasing the pressure of the withdrawn liquefied cryogenic fuel, and feeding to a vehicle fuel tank;
and (c) a second conduit communicating with the vapor space in the primary storage tank and with the first conduit downstream of the pump, the second conduit including a compressor for withdrawing cryogenic fuel from the vapor space, increasing the pressure of cryogenic fuel and feeding it to the first conduit for mixture with the pressurized liquefied cryogenic fuel to form a warmed and pressurized liquefied cryogenic fuel that is at a subcooled or near saturated condition.

18. The apparatus of claim 17 and further comprising:
(a) a third conduit communicating with the primary tank and having means for communicating with a vehicle fuel tank, the third conduit for receiving fluid from the vehicle fuel tank and feeding it to the primary tank to reduce the internal pressure of the vehicle fuel tank.

19. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition;
(c) reducing the internal pressure of an insulated vehicle fuel tank by allowing fluid to flow from the vehicle fuel tank to the primary insulated storage tank, the vehicle fuel tank being adapted to safely contain and store the liquefied cryogenic fuel in liquid form at an approximate saturated condition; and (d) feeding the warmed and pressurized liquefied cryogenic fuel to the vehicle fuel tank.

20. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;

(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cryogenic fuel to a vehicle fuel tank, the vehicle fuel tank being adapted to safely contain and store the said liquefied cryogenic fuel in liquid form, at an approximate saturated condition;
and (d) feeding warmed and pressurized liquefied cryogenic fuel from the heat exchanger to the primary tank to maintain the pressure in the primary tank above a predetermined minimum pressure.

21. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a subcooled or near saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cryogenic fuel through a restrictor to a vehicle fuel tank;
(d) sensing pressure drop across the restrictor; and (e) maintaining a predetermined rate of flow of liquefied cryogenic fuel to the vehicle tank in response to a pressure drop across the restrictor.

22. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure and temperature of some of the withdrawn liquefied cryogenic fuel to form pressurized cryogenic fuel at a temperature approaching that of a heat source;
(c) increasing the pressure of the remainder of the withdrawn liquefied cryogenic fuel;
(d) mixing pressurized cryogenic fuel with pressurized liquefied cryogenic fuel to form a warmed and pressurized liquefied cryogenic fuel at a subcooled or near saturated condition; and (e) transferring warmed and pressurized liquefied cryogenic fuel to a vehicle fuel tank.

23. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a near saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to a stationary insulated cryogenic fuel dispensing tank located at a vehicle liquefied cryogenic fuel dispensing facility and storing the liquefied cryogenic fuel in the dispensing tank in an approximate saturated condition;

(d) reducing the internal pressure of a vehicle fuel tank by allowing fluid to flow from the vehicle fuel tank to the primary insulated storage tank, the vehicle fuel tank being adapted to safely contain and store the liquefied cryogenic fuel in liquid form at an approximate saturated condition;
and (e) feeding the warmed and pressurized liquefied cryogenic fuel to the vehicle fuel tank.

24. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a near saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to a stationary insulated cryogenic fuel dispensing tank located at a vehicle liquefied cryogenic fuel dispensing facility and storing the liquefied cryogenic fuel in the dispensing tank in an approximate saturated condition;
(d) reducing the internal pressure of a vehicle fuel tank by allowing fluid to flow from the vehicle fuel tank to the dispensing tank, the vehicle fuel tank being adapted to safely contain and store the liquefied cryogenic fuel in liquid form at an approximate saturated condition; and (e) feeding the warmed and pressurized liquefied cryogenic fuel to the vehicle fuel tank.

25. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a near saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to a stationary insulated cryogenic fuel dispensing tank and storing the liquefied cryogenic fuel in the dispensing tank in an approximate saturated condition;
(d) transferring liquefied cryogenic fuel from the dispensing tank to a vehicle fuel tank so that the liquefied cryogenic fuel is in an approximate saturated condition;
e) feeding warned and pressurized liquefied cryogenic fuel from the heat exchanger to the primary tank to maintain the pressure in the primary tank above a predetermined minimum pressure.

26. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and the feeding the pressurized liquefied cryogenic fuel through a heat exchanger to warm the liquefied cryogenic fuel to a near saturated liquid condition;

(c) feeding the warmed and pressurized liquefied cryogenic fuel from the heat exchanger to a stationary insulated cryogenic fuel dispensing tank and storing the liquefied cryogenic fuel in the dispensing tank in an approximate saturated condition;
(d) transferring liquefied cryogenic fuel from the dispensing tank to a vehicle fuel tank so that the liquefied cryogenic fuel is in an approximate saturated condition; and (e) feeding pressurized liquefied cryogenic fuel to the dispensing tank to maintain the pressure in the dispensing tank below a predetermined maximum pressure.

27. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure and temperature of some of the withdrawn liquefied cryogenic fuel to form pressurized and vaporized cryogenic fuel at a temperature approaching that of a heat source;
(c) increasing the pressure of the remainder of the withdrawn liquefied cryogenic fuel;
(d) mixing pressurized and vaporized cryogenic fuel with pressurized liquefied cryogenic fuel and then feeding the mixture to an insulated liquefied cryogenic fuel dispensing tank for storage at an approximate saturated condition; and (e) transferring liquefied cryogenic fuel from the dispensing tank to a vehicle fuel tank.

28. A method comprising:
(a) withdrawing liquefied cryogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cryogenic fuel and then feeding the pressurized liquefied cyrogenic fuel through a heat exchanger to warm the liquefied cyrogenic fuel to an approximate saturated liquid condition;
(c) feeding the warmed and pressurized liquefied cyrogenic fuel from the heat exchanger to a stationary insulated cyrogenic fuel dispensing tank;
(d) feeding the warmed and pressurized liquefied cyrogenic fuel from the dispensing tank through a restrictor to a vehicle fuel tank;
(e) sensing pressure drop across the restrictor; and (f) maintaining a predetermined rate of flow of liquefied cyrogenic fuel to the vehicle tank in response to a pressure drop across the restrictor.

29. A method comprising:
(a) withdrawing liquefied cyrogenic fuel from a primary insulated storage tank at a low pressure and at a temperature close to its boiling point;
(b) increasing the pressure of the withdrawn liquefied cyrogenic fuel;
(c) withdrawing cyrogenic fuel from a vapor space in the primary insulated storage tank and mixing it with the pressurized liquefied cyrogenic fuel to form a warmed and pressurized liquefied cyrogenic fuel at a subcooled or near saturated condition; and (d) transferring the warmed and pressurized liquefied cyrogenic fuel to a vehicle fuel tank.

30. The method of claim 29 and further comprising:
(a) reducing the internal pressure of a vehicle fuel tank by allowing fluid to flow from the vehicle fuel tank to the primary insulated storage tank.