AU2008219096A1

AU2008219096A1 - Apparatus and process for submerged combustion/ambient air liquefied natural gas vaporization

Info

Publication number: AU2008219096A1
Application number: AU2008219096A
Authority: AU
Inventors: Peter Falcone
Original assignee: Selas Fluid Processing Corp
Current assignee: Linde Engineering North America Inc
Priority date: 2007-02-16
Filing date: 2008-02-15
Publication date: 2008-08-28
Also published as: CN101688641A; CA2678183A1; EP2115346A1; WO2008103291A1

Description

WO 2008/103291 PCT/US2008/002045 APPARATUS AND PROCESS FOR SUBMERGED COMBUSTION/AMBIENT AIR LIQUEFIED NATURAL GAS VAPORIZATION FIELD OF THE INVENTION This invention relates to a system and method for vaporizing a cryogenic liquid 5 utilizing a submerged combustion vaporizer. BACKGROUND OF THE INVENTION It is often necessary or desirable to vaporize a cryogenic liquid, i.e., to bring about vaporization of a cryogenic liquid to a vaporized state. For example, and though a wide variety of applications exist for liquid vaporization, it is often necessary or 10 desirable to vaporize liquid natural gas (LNG), a cryogenic liquid, so that it can be handled and distributed as a fuel source. Evaporators or vaporizers of the submerged combustion type generally comprise a vessel containing a heat exchange medium (such as a water bath), an exchanger tube bundle positioned within the water bath for carrying a cryogenic liquid, and a flue 15 gas tube of a gas burner installed within the water bath for heating and consequently vaporizing the cryogenic liquid. The gas burner discharges combustion flue gases into the water bath, which heat the water and provide the heat for the vaporization of the cryogenic liquid that flows through the exchanger tube bundle. Such vaporization systems are provided, for example, by T-Thermal Company, a division of Selas Fluid 20 Processing Corporation, under the registered trademark SUB-X. Exemplary vaporization systems are also disclosed in U.S. Patent Publication No. 2006/0183064 to Rost et al. Such vaporization systems have proven to be effective in vaporizing cryogenic liquids. Nevertheless, there remains a need for improved methods and systems for 25 heating a water source in a submerged combustion vaporizer to achieve vaporization of the cryogenic liquid. SUMMARY OF THE INVENTION According to one aspect of this invention, a system is provided for vaporizing a cryogenic liquid. The system comprises a vessel for containing water, and a conduit for 30 carrying a cryogenic liquid, wherein at least a portion of the conduit is positioned within the vessel and positioned to be immersed in the water. A sparger is positioned at least partially within the vessel and configured to deliver water into the vessel, wherein heat exchanged between the water and the cryogenic liquid vaporizes the cryogenic liquid.

WO 2008/103291 PCT/US2008/002045 -2 According to another aspect of this invention, in a cryogenic liquid vaporizer system comprising a vessel for containing water and a cryogenic liquid carrying conduit positioned at least partially within the vessel, a method of vaporizing the cryogenic liquid is provided. The method comprises the steps of delivering water into the vessel 5 through a sparger positioned at least partially within the vessel, and vaporizing the cryogenic liquid by exchanging heat between the water and the cryogenic liquid within the conduit. According to yet another aspect of this invention, a method of retrofitting a cryogenic liquid vaporizer system is provided. The method comprises the steps of 10 positioning a sparger at least partially within the vessel for delivering water into the vessel, and vaporizing the cryogenic liquid by exchanging heat between the water and the cryogenic liquid within the conduit. According to yet another aspect of this invention, a sparger assembly configured to be positioned at least partially within a vessel of a cryogenic liquid 15 vaporizer is provided. The sparger assembly comprises a conduit for delivering water from a water supply and at least one sparger extending from the conduit into the vessel. A plurality of apertures are disposed on at least one sparger for delivering water into the vessel. According to another aspect of this invention a method of delivering water into a 20 cryogenic liquid vaporizer is provided. The method comprises the step of delivering water into the vessel through a series of apertures defined along a surface of the sparger. BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the invention will be described with reference to 25 several embodiments selected for illustration in the drawing, of which: FIG. 1 is a schematic block diagram of a submerged combustion vaporization system according to one exemplary embodiment of this invention; FIG. 2A is a schematic front elevation view of a submerged combustion vaporization system according to one exemplary embodiment of this invention; 30 FIG. 2B is a schematic plan view of the submerged combustion vaporization system of FIG. 2A; FIG. 2C is a cross-sectional view of the submerged combustion vaporization tank of FIG. 2B taken along the lines 2C-2C; WO 2008/103291 PCT/US2008/002045 -3 FIG. 3 is a perspective view from the back side of the submerged combustion vaporization system shown in FIGS. 2A-2C, with portions removed to reveal internal details; FIG. 4 is a perspective view from the front right side of the submerged 5 combustion vaporization system shown in FIGS. 2A-2C, with portions removed to reveal internal details; FIG. 5 is a perspective view from the bottom right side of the submerged combustion vaporization system shown in FIGS. 2A-2C, with portions removed to reveal internal details; 10 FIG. 6A is a partial top plan view of an embodiment of a water sparger assembly that can be used in the submerged combustion vaporization system illustrated in FIG. 5; and FIG. 6B is a side elevation view of the water sparger assembly of FIG. 6A. DETAILED DESCRIPTION OF THE INVENTION 15 The invention will next be illustrated with reference to the figures. Such figures are intended to be illustrative rather than limiting and are included herewith to facilitate explanation of the present invention. The figures are not necessarily rendered to any particular scale or proportion. In addition to, or even in lieu of, introducing hot flue gases into a water bath of 20 a vaporization system to effect vaporization of the cryogenic liquid, hot waste water is optionally introduced into the water bath for the purpose of transferring heat to the cryogenic liquid to achieve or promote vaporization of the cryogenic liquid. More specifically, hot waste water can be delivered into the water bath at a temperature significantly higher than the temperature profile of the receiving water bath. The hot 25 waste water may be circulated through direct contact with the receiving water bath, or, the waste water may be alternatively segregated from the receiving water bath by use of a thermally conductive coil containing the heated water that is immersed within the water bath. Introduction and removal of the hot waste water from the receiving water bath is accomplished via pipeline connections to the water bath containment vessel. 30 Additionally, pumps and agitators may be employed for generating turbulence within the receiving water bath to increase the efficiency of heat transfer between the hot water and the cryogenic liquid. Heat transfer between a hot waste water and a cryogenic liquid is facilitated through the relatively high thermal gradients between the hot waste water delivered WO 2008/103291 PCT/US2008/002045 -4 into the water bath and the water bath itself. It has been discovered, however, that vaporization can be promoted by the introduction of water at a smaller thermal gradient, e.g., at a temperature of only about 5 to about 15 degrees Fahrenheit above that of the water bath, in the absence of a high temperature water source. Specifically, 5 a vaporization system can be configured to use water at a temperature lower than aforementioned hot waste water to promote vaporization. Referring specifically to the embodiments selected for illustration in the figures, FIG. 1 provides a schematic illustration of an embodiment of a vaporization system, generally indicated by the numeral 1, according to one aspect of this invention. 10 Vaporization system 1 includes a burner 2 that is fluidly coupled to a vaporizer 3. The burner 2 is configured to receive a fuel/air mixture 4 for reaction within the burner 2. Burner 2 is also optionally configured to deliver exhaust gases 5 that are produced as a result of the reaction of the fuel/air mixture 4. The vaporizer 3 is configured to receive the exhaust gases 5 from the burner 2. Vaporizer 3 is also configured to deliver 15 exhaust gas bubbles into the water bath. In addition to, or in lieu of the exhaust gases 5, the vaporizer 3 is also configured to receive a water stream 9 from a water supply (not shown) and to return a water stream 10 at a lower temperature than water stream 9 back to the water supply. The vaporizer 3 is also configured to receive a cryogenic liquid 6 and to deliver 20 a vaporized gas 7. The hot exhaust gases 5 delivered from the burner 2 to the vaporizer 3 promotes vaporization of the cryogenic liquid 6 into a vaporized gas 7. Accordingly, the heat from exhaust gases 5 provides a heat source for the vaporization of the cryogenic liquid 6 via heat transfer within the water bath. The exhaust gases 5 received in the 25 vaporizer 3 from the burner 2 are discharged from the vaporizer 3 in the form of saturated flue gases 8 to the atmosphere. Similar to the hot exhaust gases 5 delivered from the burner 2, the water stream 9 delivered from a water supply (not shown) to the vaporizer 3 also promotes vaporization of the cryogenic liquid 6 into a vaporized gas 7. The water stream 9 may 30 be included in addition to, or in lieu of, the hot exhaust gases 5 for the vaporization of the cryogenic liquid 6. Accordingly, the heat from the water stream 9 also provides a heat source for the vaporization of the cryogenic liquid 6. The water stream 9 received in the vaporizer 3 from the water supply (not shown) is discharged from the vaporizer 3 in the form of a water stream 10 of relatively lower temperature and returned to the 35 water supply (not shown) for reheating and recirculation.

WO 2008/103291 PCT/US2008/002045 -5 FIGS. 2A and 2B provide another schematic illustration of an embodiment of a vaporization system, generally indicated by the numeral 100, according to one aspect of this invention. The vaporizer 100 generally comprises a submerged combustion vaporization (SCV) tank 122, a burner 108 configured to deliver hot gases to the SCV 5 tank 122, a water sparger assembly 12 configured to deliver water from a water supply (not shown) into the SCV tank 122, and a return conduit 53 configured to transport water of a lower temperature from the SCV tank 122 back to the water supply. The burner 108 is configured to deliver hot gases to water in the SCV tank 122 for vaporizing cryogenic liquid being distributed through the tank, as described in 10 greater detail with reference to the remaining figures. A flameless thermal oxidizer may be used in lieu of the burner 108 to generate hot gases, as described in U.S. Patent Publication No. 2006/0183064 to Rost et al., which is incorporated by reference herein in its entirety. A blower 107 is configured to deliver air through conduit 113 for urging the hot flue gases from the burner 108 into the SCV tank 122. 15 In addition to, or in lieu of the burner 108, a water sparger assembly 12 is configured to deliver a water stream to the SCV tank 122 for promoting vaporization of the cryogenic liquid, as described in greater detail with reference to the remaining figures. The water stream is delivered from a water supply (not shown), such as a water tower, for example. A suitable water tower is disclosed in U.S. Patent No. 20 6,622,492 to Eyerman, which is incorporated by reference herein in its entirety. A return conduit 53 is provided to recirculate the water stream back to the water supply for reheating and delivery back to the SCV tank 122. According to one exemplary embodiment, in operation, the flue gases resulting from the reaction of the mixture of fuel and air travels downwardly through the burner 25 108. The flue gases are then urged outwardly from the burner 108 and into a flue gas manifold and distributor assembly 116 (see FIGS. 3-5) for delivery to the SCV tank 122. The hot gases are introduced into the SCV tank 122 through the flue gas manifold and distributor assembly 116 shown in FIGS. 3-5. Gases are then exhausted from the SCV tank 122 by means of an exhaust separator 124 and an exhaust stack 126. 30 In parallel with the hot flue gases, a heated water stream is delivered from a water supply through the sparger assembly 12 into the SCV tank 122. As explained in greater detail with reference to FIG. 2C, once the water stream enters the SCV tank 122, thermal energy is exchanged between the heated water stream and the coils carrying the cryogenic liquid. The water stream is returned to the water supply at a WO 2008/103291 PCT/US2008/002045 -6 cooler temperature through return conduit 53. The heated water may be delivered and removed from the SCV tank 122, as described above, in a continuous cycle. Referring now to FIG. 2C, a cross-sectional view of the SCV tank of FIG. 2B taken along the lines 2C-2C is shown, illustrating internal details of the SCV tank 122. 5 The SCV tank 122 is at least partially filled with a heat transfer medium such as water or any other suitable heat transfer medium. The heat transfer medium may be referred to herein as a water bath. In operation, once the hot flue gases from the burner 108 are introduced into the heat transfer medium, the hot flue gases bubble up through the heat transfer medium, consequently raising the temperature of the heat 10 transfer medium, and facilitating heat transfer from the heat transfer medium to the cryogenic liquid flowing through a tubing bundle that is situated in the heat transfer medium. More specifically, the SCV tank 122 includes a tube bundle 118 through which cryogenic liquid is circulated for vaporization. Further details of the tube bundle 118 15 are described in U.S. Patent Publication No. 2006/0183064 to Rost et al. Liquid natural gas inlet and natural gas outlet manifolds are provided in the SCV tank 122 as indicated by numerals 146 and 148, respectively. It is by means of the inlet and outlet manifolds 146 and 148 that liquid natural gas, or any other cryogenic liquid, is introduced into the tube bundle and the resulting natural gas is discharged from the 20 tube bundle. According to this exemplary embodiment, the tube bundle 118 includes four (4) tubes, each extending from an inlet 146 for liquid natural gas (or other cryogenic liquid) to an outlet 148 for vaporized natural gas (or other gas). The inlet 146 and outlet 148 are provided with a plurality of openings for connection to tube bundles such 25 as tube bundle 118. Accordingly, a plurality of tube bundles 118 are positioned adjacent to each other and are connected for fluid flow communication with the inlet 146 and outlet 148 in order to provide a dense population of flow passages through which a cryogenic liquid can be passed for vaporization. For example, inlet 146 and outlet 148 can accommodate up to fifteen (15) or more tube bundles 118, each tube 30 bundle 118 optionally including four (4) tubes. In such an embodiment, the tube bundle assembly will provide sixty (60) tubes for the flow of cryogenic liquid such as liquid natural gas (LNG). Each tube bundle 118 can also have fewer or more than four tubes, and a tube bundle assembly can have fewer or more than fifteen (15) rows of tube bundles.

WO 2008/103291 PCT/US2008/002045 -7 In order to facilitate the distribution of hot gases from the burner 108 to the heat transfer medium of the SCV tank 122, a plurality of flue gas spargers 138 are uniformly positioned beneath the tube bundles 118. Interconnection between the plurality of flue gas spargers 138 and the burner 108 is described with reference to 5 FIGS. 3-5. Each flue gas sparger 138 includes multiple apertures 142 for distributing the hot flue gases within the heat transfer medium of the SCV tank 122. Heat exchange between the hot flue gases, the heat transfer medium, and the cryogenic liquid within the tube bundle 118 causes vaporization of the cryogenic liquid, yielding a cryogenic gas. This phenomena is also described in U.S. Patent Publication No. 10 2006/0183064 to Rost et al. In addition to (and to supplement) the heat provided by the flue gas spargers, a plurality of water spargers 20 are uniformly positioned beneath the flue gas spargers 138 for providing heat to the heat transfer medium within the SCV tank 122. Interconnection between each water sparger 20 and the remaining sparger assembly 15 12 shown in FIGS. 2A and 2B will be described with reference to FIGS. 3-6B. Each water sparger 20 includes multiple apertures 22, as shown, for uniform distribution of the heated water throughout the heat transfer medium of the SCV tank 122. Heat exchange between the heated water, the heat transfer medium, and the cryogenic liquid within the tube bundle 118 facilitates or assists vaporization of the cryogenic 20 liquid, in lieu of, or in addition to, the heat provided by the hot flue gases. According to one exemplary use of this invention, the temperature of the heated water distributed by the water spargers 20 is only slightly higher than the temperature profile of the heat transfer medium, e.g. a water bath, within the SCV tank 122, thereby resulting in a small thermal driving force for heat transfer. In other words, the 25 temperature gradient between the heated water distributed by the water spargers 20 and the temperature profile of the heat transfer medium is relatively small. Since the thermal driving force is limited, the water spargers 20 are configured for maximum turbulent kinetic energy release around the cryogenic tube bundle 118 to facilitate effective heat transfer between the water and the cryogenic liquid. 30 By way of non-limiting example, the temperature gradient between the heated water distributed by the water spargers 20 and the temperature profile of the heat transfer medium is about 5 to about 15 degrees Fahrenheit. Moreover, according to one exemplary embodiment of the invention, the temperature of the heat transfer medium is maintained at about 55 degrees Fahrenheit and the temperature of the 35 water delivered by the water sparger is about 65 degrees Fahrenheit. Although the thermal driving force for heat transfer is small, the water spargers 20 are uniquely WO 2008/103291 PCT/US2008/002045 -8 adapted to facilitate the delivery of large volumes of heated water into the heat transfer medium with uniform mass distribution to enable sufficient heat transfer to vaporize the cryogenic liquid within the tube bundle 118, as described in greater detail with reference to FIGS. 6A and 6B. 5 It has been discovered that delivering large volumes of heated water under small temperature gradient conditions into the heat transfer medium in combination with uniformly distributing the heated water within the SCV tank is sufficient to vaporize the cryogenic liquid within the tube bundle 118. If heated water of significantly higher temperature is unavailable, the water spargers of the present 10 invention are therefore a useful alternative. The water spargers of the present invention are useful for exploiting heated water of a lower temperature, or water that is available from an atmospheric heating process, for example. In addition to the above, the water spargers 20 significantly enhance heat transfer under reduced heat input requirements from conventional fuel combustion 15 sources, such as the burner 108. Thus, the burner 108 may be operated at a lower capacity due to the additional heat provided by the water spargers 20. It follows that a significant energy cost savings may be achieved through operation of the water sparger assembly 12. According to one exemplary use of this invention, heated water is injected 20 through the apertures 22 of the water spargers 20 beneath the flue gas spargers 138 where the water mixes in the turbulent flow region of the heat transfer medium. The turbulent flow region of the heat transfer medium is generated by hot flue gases (or air) being released from the flue gas spargers 138. Turbulent mixing and uniform mass distribution helps to ensure maximum heat transfer between the heated water and the 25 SCV tank heat transfer medium under conditions where the temperature gradient between the two is small. Referring now to FIGS. 3-5, detailed views of the internal components of the SCV tank 122 are shown. The SCV tank 122 generally comprises the water sparger assembly 12, the cryogenic tube bundle 118, the flue gas manifold and distributor 30 assembly 116, and a vessel for containing a heat transfer medium and items 12, 116 and 118. In FIGS. 3 and 4, the water sparger assembly 12, the cryogenic tube bundle 118, and the flue gas manifold and distributor assembly 116 are illustrated, while the vessel is omitted for the purposes of clarity. In FIG. 5, the water sparger assembly 12 and the flue gas manifold and distributor assembly 116 are illustrated, while the vessel 35 and the cryogenic tube bundle 118 are omitted for clarity.

WO 2008/103291 PCT/US2008/002045 -9 The water sparger assembly 12 comprises a conduit 25 for carrying water and a plurality of water spargers 20 [ten shown for illustration] fluidly connected to the conduit 25 by mating flanges 33 and 35. Each water sparger 20 extends outwardly from the conduit 25. According to one exemplary embodiment, each water sparger 5 extends through a wall of the SCV tank 122 and into the interior of the SCV tank, while the conduit 25 is positioned external to the SCV tank 122, as best shown in FIG. 2B. The water spargers 20 are positioned directly beneath the flue gas spargers 138 of the flue gas manifold and distributor assembly 116, to promote turbulent flow as described above. 10 The conduit 25 is substantially cylindrical in shape, though other cross-sectional shapes are contemplated as well. Conduit 25 is coupled to the water supply (not shown) by means of a flange 37. Plural supports 27 are provided to support the conduit 25 against a foundation of the SCV tank 122 (not shown). As best shown in FIG. 5, the flue gas manifold and distributor assembly 116, 15 hereinafter referred to as assembly 116, receives hot flue gases from the burner 108. The assembly 116 comprises a hot flue gas duct 128 and a series of flue gas spargers 138 [twenty two shown for illustration]. Each sparger 138 extends outwardly from the flue gas duct 128 and is connected to the flue gas duct 128 in order to receive hot . gases therefrom and to deliver the hot gases to the heat transfer medium within the 20 SCV tank 122. Specifically, the spargers 138 distributes the hot flue gases through apertures 142 disposed in the flue gas spargers 138 into the heat transfer medium of the SCV tank. The assembly 116 receives a stream of heated gas and divides that gas for substantially even distribution into the SCV tank 122 to encourage heat transfer between the hot gases, the heat transfer medium, and ultimately the cryogenic liquid 25 such as liquid natural gas circulating within the tube bundle 118. Moreover, the flue gas manifold and distributor assembly 116 is uninsulated and completely submerged within the water bath in order to maximize heat transfer from the flue gases to the cryogenic tube bundle 118. Each sparger 138 is provided with a closed end 140 and a plurality of openings 30 142 generally positioned along its upper surface to permit the flow of hot gases from within the sparger 138 to the heat transfer medium in the SCV tank 122. The flue gas duct 128 is substantially cylindrical in shape, though other cross sectional shapes are contemplated as well. The flue gas duct 128 is coupled to the burner 108 by means of a flange 130. The opposite end of the flue gas duct 128 is 35 encapsulated by a plate 132. Plural lifting lugs 134 are provided along a top surface of WO 2008/103291 PCT/US2008/002045 - 10 the flue gas duct 128 in order to facilitate the handling of the assembly 116 during assembly, disassembly, modification and/or maintenance. Plural supports 136 are provided to support the assembly 116 against a foundation of the SCV tank 122 (not shown). 5 Referring now to FIGS. 6A and 6B, a partial detailed view of the water sparger assembly 12 is illustrated. A partial top plan view and a side elevation view of the water sparger assembly 12 are shown respectively in FIGS. 6A and 6B. The water sparger assembly 12 generally comprises a hollow conduit 25 and a plurality of individual water spargers 20 extending therefrom. Conduit 25 is coupled to 10 the water supply by means of a flange 37. The conduit 25 and plural spargers 20 are optionally interconnected by mating flanges 33 and 35. Plural supports 27 are provided to support the water sparger assembly 12 against a foundation of the SCV tank 122 (not shown). Each water sparger 20 comprises a long hollow tube having a closed end 23. A 15 series of apertures 22 are provided on the top surface for the uniform distribution of water into the SCV tank 122. A single row of apertures 22 direct the water vertically into the heat transfer medium toward the flue gas spargers 138. The sizing of these apertures 22 is designed to provide sufficient pressure head loss, e.g., 20 PSIG, to enable uniform mass flow rate of the water, as described below. 20 According to one exemplary embodiment, and by way of non-limiting example, water sparger assembly 12 includes ten water spargers 20 extending therefrom. Each water sparger includes at least twenty-one (21) apertures 22, uniformly distributed over the surface of the water sparger, each aperture 22 having a diameter of at least about 1 3/16 inches. It should be understood that the water sparger may include any 25 number of apertures, of any diameter, in order to achieve a desired flow pattern. The water spargers 20 are configured to maximize heat transfer between the heated water and the cryogenic tube bundle 118 by circulating large quantities of heated water through the SCV tank 122, when the thermal gradient between the heated water and the heat transfer medium within the SCV tank is small. For example, and according to 30 one exemplary embodiment, the temperature difference between water contained within the vessel and heated water distributed into the vessel by the water spargers 20 may be less than fifteen (15) degrees Fahrenheit. In order to maximize heat transfer between the water distributed by the sparger and the vessel water under such a small temperature gradient, each water sparger 20 35 is configured to deliver at least about 2,800 gallons of water per minute into a vessel WO 2008/103291 PCT/US2008/002045 - 11 sized to contain at least about 30,000 gallons of water. Moreover, the ratio of the flow rate [gallons/minute] of the water distributed into the vessel by a total of ten water spargers 20 (28,000 gallons of water per minute) to the volume of water contained within the vessel [gallons] may be greater than about 0.9:1. 5 The discharge velocity of the water from each water sparger 20 coupled with the buoyant forces provided by flue gases or air exiting the flue gas spargers 138 encourages the water to travel toward and commingle with the cryogenic tube bundle 118, thereby maximizing heat transfer between the water and the cryogenic tube bundle 118. Furthermore, the trajectory and high discharge velocity of the water 10 delivered into the SCV tank 122 by each water sparger 20 discourages the water from bypassing the cryogenic tube bundle 118 and traveling directly to the water return conduit 53 shown in FIGS. 2A and 2B. This adverse phenomena is referred to herein as "short circuiting." . In addition to circulating large quantities of heated water through the SCV tank 15 122, the water spargers 20 are configured to uniformly distribute heated water across the heat transfer surfaces of the tube bundle 118 to enhance the heat transfer rate and discourage short circuiting. Further to the need for uniform distribution of heated water, the water spargers minimize the cycling time of the heated water within the SCV tank. Such short cycling will tend to reduce overall thermal efficiency. 20 One skilled in the art will recognize that the sparger assembly 12 may be tailored in a variety of different configurations, and may include any number of spargers 20 having any number of apertures 22 arranged in a variety of positions to tailor the flow of water through the SCV tank 122. According to one exemplary use of the invention, the sparger assembly 12 may 25 be retrofitted onto an existing submerged combustion vaporizer (SCV) for circulating heated water into the SCV tank of the vaporizer. It is envisioned that the water spargers 20 may be positioned through the wall of the SCV tank and immersed within the heat transfer medium contained within the SCV tank. In this manner, the retrofitted SCV may be employed in an application where hot water is not available, to 30 exploit a favorable climate, to reduce reliance on a fuel fired burner or other heat producing means, or to leverage any other of the aforementioned benefits of the water sparger assembly. While specific embodiments of a water sparger assembly 12 are shown in the figures for purposes of illustration, a wide variety of configurations can be used in order 35 to deliver water to a heat transfer medium of a vaporizer. Depending on a particular WO 2008/103291 PCT/US2008/002045 - 12 application or size constraints for a vaporization system, the water sparger assembly can have a wide variety of shapes, sizes, and configurations. Preferably, however, the assembly will be configured to distribute large quantities of water in a substantially uniform fashion into the heat transfer medium so that heat can be evenly distributed 5 for the vaporization of cryogenic liquid. Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention. 10 While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the 15 invention.

Claims

1. A system for vaporizing a cryogenic liquid comprising: a vessel for containing water; a conduit for carrying a cryogenic liquid, wherein at least a portion of 5 said conduit is positioned within said vessel and positioned to be immersed in the water; and at least one water sparger positioned at least partially within the vessel and configured to deliver water into said vessel, wherein heat exchanged between the water and the cryogenic liquid vaporizes the cryogenic liquid. 10

2. The system of claim 1 further comprising a plurality of apertures disposed on said water sparger for distributing water into said vessel.

3. The system of claim 2 wherein a diameter of each of said apertures of said water sparger is about 1 3/16 inches.

4. The system of claim 3, wherein each water sparger comprises at 15 least 21 apertures.

5. The system of claim 1, further comprising a plurality of water spargers uniformly positioned within said vessel.

6. The system of claim 1, wherein said water sparger is configured to deliver at least about 2,800 gallons of water per minute into a vessel sized to 20 contain at least about 30,000 gallons of water.

7. The system of claim 1, wherein a ratio of the total flow rate [gallons/minute] of the water distributed into the vessel by the at least one water sparger to the volume of water contained within the vessel [gallons] is greater than about 0.09 : 1. 25

8. The system of claim 1 further comprising at least one flue gas conduit positioned at least partially within the vessel and configured to deliver flue gas into said vessel.

9. The system of claim 1, wherein at least a portion of said flue gas conduit is positioned between said conduit for carrying a cryogenic liquid and said 30 water sparger. WO 2008/103291 PCT/US2008/002045 - 14

10. The system of claim 8, wherein a temperature difference between water contained within the vessel and water distributed into the vessel by the water sparger is less than about 15 degrees Fahrenheit.

11. In a cryogenic liquid vaporizer system comprising a vessel for 5 containing water and a cryogenic liquid carrying conduit positioned at least partially within the vessel, a method of vaporizing the cryogenic liquid comprising the steps of: delivering water into the vessel through a water sparger positioned at least partially within the vessel; and vaporizing the cryogenic liquid by exchanging heat between the water 10 and the cryogenic liquid within the conduit.

12. The method of claim 11, wherein the step of delivering water into the vessel comprises delivering at least about 28,000 gallons of water per minute into the vessel sized to contain at least about 30,000 gallons of water.

13. The method of claim 11, further comprising maintaining a 15 temperature of the water being delivered into the vessel at about 5 to about 15 degrees Fahrenheit greater than a temperature of the water contained within the vessel.

14. The method of claim 11 further comprising the step of delivering flue gases through a flue gas conduit into the vessel at a location between the water 20 sparger and the cryogenic liquid carrying conduit.

15. The method of claim 11 further comprising the steps of drawing water from the vessel and distributing the water to a water supply.

16. A method of retrofitting a cryogenic liquid vaporizer system comprising a vessel for containing water and a cryogenic liquid carrying conduit 25 positioned at least partially within the vessel, said method including the steps of: positioning a water sparger at least partially within the vessel for delivering water into the vessel; and vaporizing the cryogenic liquid by exchanging heat between the water and the cryogenic liquid within the conduit. 30

17. A water sparger assembly configured to be positioned at least partially within a vessel of a cryogenic liquid vaporizer, said water sparger assembly comprising: a conduit for delivering water from a water supply; WO 2008/103291 PCT/US2008/002045 - 15 at least one water sparger extending from the conduit into the vessel; and a plurality of apertures defined in the at least one water sparger for delivering water into the vessel. 5

18. The water sparger assembly of claim 17, wherein a diameter of each of said apertures of said water sparger is about 1 3/16 inches.

19. The water sparger assembly of claim 17, wherein each water sparger comprises at least 21 apertures.

20. The water sparger assembly of claim 17, wherein each water 10 sparger is configured to deliver at least about 2,800 gallons of water per minute into a vessel.

21. A method of delivering water into a cryogenic liquid vaporizer including a vessel for containing water and a sparger positioned at least partially within the vessel, said method comprising the step of delivering water into the vessel through 15 a series of apertures defined along a surface of the sparger.