JP7467028B2 - Low-temperature liquefied gas vaporizer, cooling system, and method for suppressing ice formation in the vaporizer - Google Patents

Description

The present invention relates to a low-temperature liquefied gas vaporizer, a cooling system, and a method for suppressing ice formation in the vaporizer.

Conventionally, a vaporizer for low-temperature liquefied gas is known, as disclosed in the following Patent Document 1. The vaporizer disclosed in Patent Document 1 is provided with a shell into which water, which is a fluid to be cooled, a heat transfer tube disposed within the shell and into which low-temperature liquefied gas, which is a low-temperature fluid, flows, a side wall disposed within the shell parallel to the heat transfer tube, and a flow rate adjustment unit that reduces the flow rate of water flowing between the heat transfer tube and the side wall. In this vaporizer, the provision of the flow rate adjustment unit ensures a sufficient flow rate between the heat transfer tubes. This prevents problems such as icing caused by a decrease in flow rate.

Patent No. 4313605

Patent Document 1 states that the flow of water between the heat transfer tubes is ensured by reducing the flow rate of water flowing between the heat transfer tubes and the side wall. However, water flow may not be ensured where the heat transfer tubes come into contact with their outer surfaces, which may result in icing.

The present invention was made in consideration of the above-mentioned conventional technology, and its purpose is to make it possible to suppress freezing of water even when no water flow occurs near the outer surface of the heat transfer tube.

In order to achieve the above-mentioned object, the present invention provides a low-temperature liquefied gas vaporizer comprising: a shell having an inner space extending in one direction, into which water is introduced; a heat transfer tube disposed in the inner space, into which low-temperature liquefied gas is introduced and into which the low-temperature liquefied gas is heated by the water; and a heat transfer suppressing member formed of a material having a lower thermal conductivity than water, wherein the outer peripheral surface of the shell is provided with the water inlet port and the water outlet port, one end of the heat transfer tube, which is the inlet side of the low-temperature liquefied gas, is inserted into a partition wall disposed at one end in the one direction of the inner space, the partition wall is disposed so as to be located upstream in the flow direction of the low-temperature liquefied gas in the heat transfer tube relative to the inlet port , which is located upstream in the flow direction of the low-temperature liquefied gas, and the heat transfer suppressing member covers the heat transfer tube in a part of the heat transfer tube including the inlet portion of the low-temperature liquefied gas, and suppresses freezing of water even when no water flow occurs around the heat transfer tube.

In the present invention, the portion where the low-temperature liquefied gas flows in a liquid state is covered with a heat transfer suppression member. That is, the portion where the low-temperature liquefied gas is introduced into the heat transfer tube is the portion of the heat transfer tube that is the coldest. This portion is covered with a heat transfer suppression member made of a material with a lower thermal conductivity than water. Therefore, the cold of the low-temperature liquefied gas in the heat transfer tube is transferred to the water via the heat transfer tube and the heat transfer suppression member, so that the heat transfer to the water can be suppressed compared to the case where the cold of the low-temperature liquefied gas is transferred directly from the heat transfer tube to the water. Therefore, even if no water flow occurs near the outer surface of the heat transfer tube, the freezing of water around the heat transfer tube can be suppressed. In addition, if ice occurs without a heat transfer suppression member, the ice grows large in the thickness direction and length direction, and ice blockage of the heat transfer tube gap is likely to occur. In order to prevent this, it is necessary to increase the temperature of the water supplied, but by providing the heat transfer suppression member, it becomes possible to suppress blockage due to ice even if the temperature of the water supplied is set to be low.

The heat transfer suppression member may cover the heat transfer tube over the area where the low-temperature liquefied gas begins to evaporate, or, when the low-temperature liquefied gas flows through the heat transfer tube in a supercritical fluid state, over the range from the introduction site of the low-temperature liquefied gas to the area where the low-temperature liquefied gas is heated without a phase change .

At the portion where the low-temperature liquefied gas starts to evaporate, the low-temperature liquefied gas is likely to absorb heat from the heat transfer tube. However, since this portion is also covered with the heat transfer suppressing member, the heat transfer tube is prevented from absorbing heat from the surrounding water. Therefore, even if water does not flow near the outer surface of the heat transfer tube, water can be prevented from freezing around the heat transfer tube. Furthermore, when the low-temperature liquefied gas flows through the heat transfer tube in a supercritical fluid state, the low-temperature heat transfer tube is prevented from absorbing heat from the surrounding water by providing the heat transfer suppressing member at the portion where the low-temperature liquefied gas is heated without undergoing a phase change at a low temperature. Therefore, even if water does not flow near the outer surface of the heat transfer tube, water can be prevented from freezing around the heat transfer tube.

The heat transfer suppression member may be made of a resin-based material, a glass-based material, a rubber-based material, or a ceramic-based material.

The heat transfer suppression member may be composed of a member with a C-shaped cross section, a pipe-shaped member, or two halves.

If the heat transfer suppression member is composed of a member with a C-shaped cross section, the heat transfer suppression member can be attached to the heat transfer tube from the outside by opening the slit portion. Therefore, the installation work of the heat transfer suppression member can be prevented from becoming cumbersome. Moreover, the installation work when attaching the heat transfer suppression member to the heat transfer tube of an existing vaporizer is also not cumbersome. Furthermore, if the heat transfer suppression member is composed of a pipe-shaped member, there is no cut in the circumferential direction of the heat transfer tube, so water can be prevented from penetrating inside the heat transfer suppression member. Furthermore, even if the heat transfer suppression member is composed of two half-shaped members, the installation work of the heat transfer suppression member can be prevented from becoming cumbersome. Moreover, the installation work when attaching the heat transfer suppression member to the heat transfer tube of an existing vaporizer is also not cumbersome.

The heat transfer suppression member may be attached to the heat transfer tube from the outside so as to be detachable from the heat transfer tube. In this embodiment, even if it becomes necessary to replace the heat transfer suppression member, this can be easily handled.

The heat transfer suppressing member may be configured as a member having a C-shaped cross section and a slit. In this case, a second heat transfer suppressing member may be provided to cover the slit of the heat transfer suppressing member. In this embodiment, it is possible to suppress the intrusion of water through the slit. In other words, it is possible to achieve both the simplification of the installation work of the heat transfer suppressing member and the effect of preventing the intrusion of water.

The heat transfer suppression member may be composed of a plurality of divided members arranged in the direction in which the heat transfer tube extends. In this case, a second heat transfer suppression member may be provided, which is made of a material with a lower thermal conductivity than water and covers the spaces between the divided members. In this aspect, the heat transfer suppression member can be attached to the heat transfer tube by arranging the plurality of divided members in the direction in which the heat transfer tube extends. Therefore, even if the heat transfer tube is very long, there is no need to prepare a very long, integrated heat transfer suppression member, and the installation work of the heat transfer suppression member can be prevented from becoming complicated. Moreover, since the second heat transfer suppression member covers the spaces between the divided members, it is possible to prevent water from entering between the divided members.

The heat transfer suppression member may be composed of multiple divided members arranged in the direction in which the heat transfer tube extends. In this case, one end of adjacent divided members may cover the end of the other divided member. In this embodiment, the ends of the divided members do not come into contact with each other, so water can be prevented from entering through the gaps between the ends. Furthermore, even if the heat transfer tube is very long, there is no need to prepare a very long, integrated heat transfer suppression member, so the installation work of the heat transfer suppression member can be prevented from becoming complicated.

A plurality of the heat transfer tubes may be provided, in which case each of the plurality of heat transfer tubes has a shape that extends vertically while having a plurality of straight pipe sections and a plurality of bend sections, the low-temperature liquefied gas is introduced into the straight pipe section located at the lowest position among the plurality of straight pipe sections, and the heat transfer suppressing member may be attached to the straight pipe section located at the lowest position in each heat transfer tube, covering the heat transfer tube in a part of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, while not being attached to the bend section located at the lowest position. In this aspect , the straight pipe section located at the lowest position among the heat transfer tubes is the part that becomes the coldest in the heat transfer tube, and therefore, by providing the heat transfer suppressing member in this part, freezing of water around the heat transfer tube can be effectively suppressed.

The plurality of bends arranged in the vertical direction among the plurality of bends include at least one first bend and at least one second bend that is recessed from the first bend in the extension direction of the straight pipe section, and the at least one first bend and the at least one second bend may be arranged alternately. In this case, the weld between the at least one first bend and the straight pipe section may protrude in the extension direction of the straight pipe section more than the weld between the at least one second bend and the straight pipe section.

In this embodiment, the width of the space adjacent to the weld between the first bend and the straight pipe section on the second bend side can be prevented from narrowing. This prevents the adjacent straight pipe section from getting in the way when welding the first bend to the straight pipe section or when inspecting the weld.

The low-temperature liquefied gas vaporizer may further include an adjacent heat transfer tube arranged adjacent to the heat transfer tube in the inner space, into which low-temperature liquefied gas is introduced and into which the low-temperature liquefied gas is heated by the water. In this case, the adjacent heat transfer tube may have a shape that has a plurality of straight tube sections and a plurality of bend sections and extends vertically while meandering. In addition, the plurality of bend sections arranged vertically among the plurality of bend sections in the adjacent heat transfer tube may include at least one adjacent first bend section adjacent to the at least one first bend section and at least one adjacent second bend section adjacent to the at least one second bend section, and the at least one adjacent first bend section and the at least one adjacent second bend section may be arranged alternately. In this case, the weld between the at least one adjacent second bend section and the straight pipe section may protrude further in the extension direction of the straight pipe section than the weld between the at least one adjacent first bend section and the straight pipe section, and may protrude further in the extension direction of the straight pipe section than the weld between the at least one second bend section and the straight pipe section.

In this embodiment, the width of the space adjacent to the weld between the adjacent second bend and the straight pipe section on the adjacent first bend side and the second bend side can be prevented from narrowing. Therefore, the adjacent straight pipe section can be prevented from getting in the way during the work of welding the adjacent second bend to the straight pipe section and the work of inspecting the weld.

The low-temperature liquefied gas vaporizer may include an inlet chamber into which the low-temperature liquefied gas flows, and an outlet chamber into which gas vaporized from the low-temperature liquefied gas in the heat transfer tube flows. In this case, the heat transfer tube may be configured as a straight tube that linearly connects the inlet chamber and the outlet chamber. The heat transfer suppression member may cover a predetermined range of the heat transfer tube from the inlet chamber. In this aspect, the heat transfer suppression member covers the portion of the heat transfer tube on the inlet chamber side, which is the coldest. This makes it possible to effectively suppress freezing of water around the heat transfer tube.

A plurality of the heat transfer tubes may be provided, in which case each of the plurality of heat transfer tubes is constituted by a U-shaped tube, the low-temperature liquefied gas is introduced into a lower straight tube portion of the U-shaped tube, and the heat transfer suppressing member covers the lower straight tube portion of each heat transfer tube, thereby covering the heat transfer tube in a part of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, while not being attached to a bent portion of the U-shaped tube. In this aspect , the lower straight tube portion of the heat transfer tube is the part that becomes the coldest in the heat transfer tube, so that the heat transfer suppressing member is provided in this part, thereby making it possible to effectively suppress freezing of water around the heat transfer tube.

The low-temperature liquefied gas vaporizer may include an inlet chamber into which the low-temperature liquefied gas flows, and an outlet chamber into which gas vaporized from the low-temperature liquefied gas in the heat transfer tube flows in. In this case, the introduction port may be disposed at a position in the shell adjacent to the inlet chamber.

In this embodiment, water with a large calorific value is introduced into the part of the low-temperature liquefied gas that has the lowest temperature, so freezing of the water can be further suppressed.

The present invention is a cooling system that includes the vaporizer and a cooler into which water cooled by the low-temperature liquefied gas in the vaporizer is introduced.

In this cooling system, the water cooled by the low-temperature liquefied gas in the evaporator is used in the cooler to cool the object to be cooled. Therefore, the cold energy of the low-temperature liquefied gas can be used to cool the object to be cooled. Furthermore, the provision of a heat transfer suppression member in the evaporator prevents the water from freezing. Therefore, even if the temperature of the water introduced into the evaporator is set to be lower, blockage due to icing of the gaps in the heat transfer tubes inside the evaporator is suppressed, so it is possible to set the evaporator so that the temperature of the water drawn out from inside the evaporator is lower. Therefore, the performance of the cooling system can be improved.

The present invention is a method for suppressing ice formation in a carburetor, comprising: a shell having an inner space extending in one direction, into which water is introduced; and a heat transfer tube disposed in the inner space, into which low-temperature liquefied gas is introduced and which heats the low-temperature liquefied gas with the water, the outer peripheral surface of the shell being provided with the water inlet port and the water outlet port, one end of the heat transfer tube, which is the inlet side of the low-temperature liquefied gas, is inserted into a partition wall disposed at one end in the one direction of the inner space, the partition wall being disposed so as to be located upstream in the flow direction of the low-temperature liquefied gas in the heat transfer tube than the inlet port , which is located upstream in the flow direction of the low-temperature liquefied gas, the method comprising: attaching a heat transfer suppression member formed of a material having a lower thermal conductivity than water to the outer surface of a part of the heat transfer tube including the inlet portion of the low-temperature liquefied gas in the heat transfer tube; and suppressing freezing of water even when no water flow occurs around the heat transfer tube.

As described above, according to the present invention, water freezing can be suppressed even when no water flow occurs near the outer surface of the heat transfer tube.

1 is a diagram showing an overall configuration of a low-temperature liquefied gas vaporizer according to a first embodiment. FIG. 4 is a diagram showing a heat transfer tube and a heat transfer suppressing member provided in the low-temperature liquefied gas vaporizer. FIG. 11 is a diagram partially illustrating a member having a C-shaped cross section that constitutes the heat transfer suppressing member. FIG. 13 is a perspective view of a heat-transfer suppressing member formed of a tubular member. FIG. 13 is a diagram of a heat-transfer suppressing member formed of two halves. FIG. 13A and 13B are diagrams illustrating a state in which a second heat transfer suppressing member is provided. 13A and 13B are diagrams illustrating a state in which the heat-transfer suppressing member is made up of a plurality of divided members and a second heat-transfer suppressing member is provided. 13A and 13B are diagrams illustrating a state in which a heat-transfer suppressing member is made up of a plurality of divided members, and the divided members are arranged with their ends overlapping each other. FIG. 1 shows a vaporizer configuration in which two inlet ports are provided in the shell. FIG. 1 is a diagram showing the configuration of a low-temperature liquefied gas vaporizer in which a heat transfer tube is constituted by a U-shaped tube. FIG. 1 is a diagram showing the configuration of a low-temperature liquefied gas vaporizer having a heating section provided inside a shell. 11 is a diagram for explaining a case where the heat transfer tube is constituted by a meandering tube. FIG. 1 is a diagram for explaining a low-temperature liquefied gas vaporizer having a heat transfer tube in which first bend portions and second bend portions are arranged alternately. FIG. 1A is a partial side view of a heat transfer tube group for explaining the positional relationship of bends of a plurality of heat transfer tubes provided in a low-temperature liquefied gas vaporizer, and FIG. 1B is a partial plan view of a heat transfer tube group for explaining the positional relationship of bends of a plurality of heat transfer tubes provided in a low-temperature liquefied gas vaporizer. FIG. 11 is a diagram illustrating a schematic overall configuration of a cooling system according to a second embodiment.

The following describes in detail the embodiment of the present invention with reference to the drawings.

First Embodiment
As shown in Fig. 1, a low-temperature liquefied gas vaporizer (hereinafter, simply referred to as a vaporizer) 10 according to the first embodiment is a vaporizer 10 for heating and vaporizing liquefied natural gas (LNG), which is a low-temperature liquefied gas, with water (seawater, industrial water, etc.). The low-temperature liquefied gas referred to here is a gas that is in a gaseous state at room temperature and liquefied at a low temperature, so the vaporizer 10 may be used to vaporize liquefied gases such as liquefied petroleum gas (LPG) and liquefied hydrogen (LH2).

The vaporizer 10 is a shell-and-tube type heat exchanger, and includes a shell 12 and a number of heat transfer tubes 14 arranged within the shell 12. The shell 12 is hollow and elongated in one direction. An inlet chamber 16 is connected to one longitudinal end of the shell 12. Liquefied natural gas is introduced into the inlet chamber 16 through an inlet port 16a from an external pipe (not shown). An outlet chamber 18 is connected to the other longitudinal end of the shell 12. Natural gas (NG) vaporized from the liquefied natural gas flows into the outlet chamber 18, and this natural gas is discharged to an external pipe (not shown) through the outlet port 18a.

The shell 12 is provided with a water (heat source medium) inlet port 21 and a water outlet port 22. Water is introduced from the outside into the inner space IS of the shell 12 through the inlet port 21. The water in the inner space is discharged to the outside through the outlet port 22. The water inlet port 21 may be disposed adjacent to the inlet chamber 16 in the shell 12, or may be disposed adjacent to the outlet chamber 18. The water outlet port 22 may be disposed adjacent to the outlet chamber 18 in the shell 12, or may be disposed adjacent to the inlet chamber 16. In this embodiment, the inlet port 21 is disposed adjacent to the inlet chamber 16 in the shell 12, and the outlet port 22 is disposed adjacent to the outlet chamber 18 in the shell 12. By disposing the inlet port 21 near the inlet chamber 16, the heat source medium with the largest amount of heat is introduced to the place with the lowest temperature, which further suppresses freezing of water. That is, when water flows into the inner space IS of the shell 12 through the inlet port 21, the water comes into contact with the end of the heat transfer tube 14 (heat transfer suppression member 30 described below) on the inlet chamber 16 side before changing its flow direction. This makes it possible to further suppress freezing at the end of the heat transfer tube 14 (heat transfer suppression member 30 described below) on the inlet chamber 16 side. In addition, because the outlet port 22 is located on the opposite side of the inlet chamber 16, water can easily flow along the heat transfer tube 14 inside the shell 12, allowing for efficient heat exchange.

The heat transfer tubes 14 have a shape that extends linearly and are arranged in the inner space IS of the shell 12. The heat transfer tubes 14 are bridged between the inlet chamber 16 and the outlet chamber 18. That is, the partition wall 16b that separates the inner space IS from the inlet chamber 16 is configured as a tube plate that supports one end of the heat transfer tubes 14. The partition wall 18b that separates the inner space IS from the outlet chamber 18 is configured as a tube plate that supports the other end of the heat transfer tubes 14. The liquefied natural gas in the inlet chamber 16 flows into each heat transfer tube 14. This liquefied natural gas vaporizes in the heat transfer tubes 14 and becomes natural gas, and this natural gas merges in the outlet chamber 18.

The heat transfer tube 14 is made of stainless steel, titanium, titanium alloy, steel, etc.

The shell 12 is provided with a plurality of baffle plates 25. The baffle plates 25 are provided to control the flow direction of the water flowing in the inner space IS. The baffle plates 25 are arranged at intervals in the longitudinal direction of the shell 12. A gap is formed between the baffle plate 25 and the inner surface of the shell 12 in a direction perpendicular to the longitudinal direction. This gap is located on the opposite side of the adjacent baffle plates 25 in the direction perpendicular to the longitudinal direction. The introduction port 21 is disposed between the partition wall 16b on the inlet chamber 16 side and the baffle plate 25 closest to this partition wall 16b. The discharge port 22 is disposed between the partition wall 18b on the outlet chamber 18 side and the baffle plate 25 closest to this partition wall 18b. Therefore, a meandering water flow is generated in the inner space IS from the introduction port 21 to the discharge port 22.

The heat transfer tube 14 is provided with a heat transfer suppression member 30 made of a material with a lower thermal conductivity than water. Therefore, the thermal conductivity of the heat transfer suppression member 30 is lower than the thermal conductivity of the material that constitutes the heat transfer tube 14. The heat transfer suppression member 30 is attached to only a portion of the heat transfer tube 14 in the longitudinal direction, so that a portion of the heat transfer tube 14 is covered by the heat transfer suppression member 30, but the other portion of the heat transfer tube 14 is not covered by the heat transfer suppression member 30 and is exposed.

The portion of the heat transfer tube 14 covered by the heat transfer suppression member 30 is the range from the portion where the low-temperature liquefied gas is introduced to the portion where the low-temperature liquefied gas starts to evaporate. That is, the portion where the heat transfer suppression member 30 is provided is a portion of the heat transfer tube 14 including one end portion connected to the partition wall 16b on the inlet chamber 16 side of the heat transfer tube 14. In other words, the portion where the heat transfer suppression member 30 is provided includes the portion of the heat transfer tube 14 where the liquefied natural gas is introduced. The range where the heat transfer suppression member 30 is provided extends from the one end portion to the middle portion of the heat transfer tube 14. The portion where the liquefied natural gas starts to evaporate is affected by the pressure, flow rate, and water flow rate and temperature of the liquefied natural gas, so the range where the heat transfer suppression member 30 is attached is adjusted according to these pressures, flow rates, and temperatures. In the area downstream of this area in the flow direction of the liquefied natural gas, i.e., the area where the natural gas is further heated after all the liquefied natural gas has evaporated, the heat transfer suppression member 30 is not provided and the heat transfer tube 14 is exposed. When the low-temperature liquefied gas flows through the heat transfer tube 14 in a supercritical fluid state, the heat transfer suppression member 30 is provided in a range extending from the area where the low-temperature liquefied gas is introduced to the area where the low-temperature liquefied gas is heated without undergoing a phase change in a low-temperature state.

The heat transfer suppression member 30 covers a predetermined range from the inlet chamber 16. That is, the heat transfer suppression member 30 is disposed beyond the end on the inlet chamber 16 side, beyond the baffle plate 25 located closest to the inlet chamber 16. That is, the baffle plate 25 is formed with a through hole through which the heat transfer tube 14 to which the heat transfer suppression member 30 is attached can be inserted, and the heat transfer suppression member 30 passes through this through hole. A gap may be formed between the inner peripheral surface of the through hole in the baffle plate 25 and the outer peripheral surface of the heat transfer suppression member 30. In this way, the task of inserting the heat transfer tube 14 into the through hole of the baffle plate 25 is not complicated.

The heat transfer suppression member 30 may be a coating formed on the outer surface of the heat transfer tube 14. That is, the heat transfer suppression member 30 may be configured to be formed on the outer surface of the heat transfer tube 14 by being applied onto the heat transfer tube 14. However, this is not limited to this. That is, the heat transfer suppression member 30 may be provided on the heat transfer tube 14 by covering the heat transfer tube 14 with an independently formed member.

In the first embodiment, as shown in Figs. 2 and 3, the heat transfer suppression member 30 is formed of a member 32 with a C-shaped cross section and a slit 32a extending over the entire length, and is attached to the outside of the heat transfer tube 14. That is, when attaching the heat transfer suppression member 30 to the heat transfer tube 14, the slit 32a of the member 32 is opened, and in this state, the member 32 is attached to the heat transfer tube 14 from the outside. Therefore, in an existing vaporizer 10, it is also possible to attach the heat transfer suppression member 30 to the heat transfer tube 14 without disassembling the heat transfer tube 14. Note that the heat transfer suppression member 30 may be formed of a pipe-shaped member instead of the member 32 with a C-shaped cross section.

When the heat transfer suppression member 30 is attached to the heat transfer tube 14, the slit 32a may be in an open state or in a closed state. Water may enter the inside of the heat transfer suppression member 30 through the slit 32a. However, even if this water freezes, ice will not grow on the outside of the heat transfer suppression member 30.

In this embodiment, the heat transfer suppression member 30 is detachable from the heat transfer tube 14. However, this is not limited to this, and the heat transfer suppression member 30 may be adhered to the heat transfer tube 14 with an adhesive or the like.

The heat transfer suppression member 30 may be made of a resin-based material, a glass-based material, a rubber-based material, or a ceramic-based material, as long as it is made of a material with a lower thermal conductivity than water. This makes it possible to suppress the cold heat of the liquid liquefied natural gas from being transferred to the water via the heat transfer tube 14.

Water (heat source medium) flows into the inner space IS of the shell 12 through the inlet port 21. Meanwhile, liquefied natural gas flows into the heat transfer tube 14 from the inlet chamber 16. The liquefied natural gas that flows into the heat transfer tube 14 gradually heats up through heat exchange with the water. However, because the heat transfer tube 14 near the inlet chamber 16 is covered with a heat transfer suppression member 30, the heating of the liquefied natural gas is suppressed, and heat exchange with the water is also suppressed. As a result, the cooling of the water present around the heat transfer suppression member 30 is suppressed, and the freezing of the water is also suppressed.

Nevertheless, the liquefied natural gas inside the heat transfer tube 14 is gradually heated, and begins to evaporate inside the heat transfer tube 14 that is covered with the heat transfer suppression member 30. Then, after passing the portion of the heat transfer tube 14 that is covered with the heat transfer suppression member 30, the entire amount of liquefied natural gas vaporizes as it flows through the heat transfer tube 14, becoming gas (LNG). The gas flows from the heat transfer tube 14 into the outlet chamber 18, and is then sent to the user equipment through an external pipe.

As described above, in the first embodiment, the portion where the liquefied natural gas flows in a liquid state is covered with the heat transfer suppression member 30, and the portion where the liquefied natural gas starts to evaporate is also covered with the heat transfer suppression member 30. On the other hand, the heat transfer tube 14 is not covered with the heat transfer suppression member 30 in portions other than these portions. That is, the portion where the liquefied natural gas is introduced into the heat transfer tube 14 is the portion of the heat transfer tube 14 that becomes the coldest. This portion is covered with the heat transfer suppression member 30 formed of a material with a lower thermal conductivity than water. Therefore, since the cold of the liquefied natural gas in the heat transfer tube 14 is transferred to the water via the heat transfer tube 14 and the heat transfer suppression member 30, the heat transfer to the water can be suppressed compared to the case where the cold of the liquefied natural gas is transferred directly from the heat transfer tube 14 to the water. Therefore, even if the water does not flow near the outer surface of the heat transfer tube 14, the water around the heat transfer tube 14 can be suppressed from freezing. Furthermore, in the area where the liquefied natural gas begins to evaporate, the liquefied natural gas is likely to absorb heat from the heat transfer tube 14. However, because this area is also covered with the heat transfer suppression member 30, the heat transfer tube 14 is suppressed from absorbing heat from the surrounding water. Therefore, even if no water flow occurs near the outer surface of the heat transfer tube 14, it is possible to suppress the water from freezing around the heat transfer tube 14.

In addition, in the first embodiment, the heat transfer suppression member 30 is composed of a member 32 with a C-shaped cross section, so that the heat transfer suppression member 30 can be attached to the heat transfer tube 14 from the outside by opening the slit 32a. This prevents the installation work of the heat transfer suppression member 30 from becoming cumbersome.

In the first embodiment, the heat transfer suppression member 30 is formed by a member 32 having a C-shaped cross section, but this is not limited thereto. For example, as shown in FIG. 4, the heat transfer suppression member 30 may be formed by a tubular member 34. In this case, the tubular member 34 can be attached to the heat transfer tube 14 by attaching it to one end of the heat transfer tube 14 before the heat transfer tube 14 is spanned between the partition walls 16b and 18b. In this configuration, there is no cut in the circumferential direction of the heat transfer tube 14, so water can be prevented from entering the inside of the heat transfer suppression member 30.

The heat transfer suppression member 30 may be composed of two halves 35 having a semicircular cross section, as shown in FIG. 5. In this case, it is also possible to attach the heat transfer suppression member 30 to the heat transfer tube 14 of the existing vaporizer 10 later. The halves 35 may be adhered to the heat transfer tube 14 with an adhesive, or may be fixed to the heat transfer tube 14 by wrapping a belt member (not shown) around it.

In addition, when the heat transfer suppressing member 30 is formed of a member 32 having a C-shaped cross section, a second heat transfer suppressing member 37 may be provided on the outside of the heat transfer suppressing member 30 as shown in FIG. 6. The second heat transfer suppressing member 37 is formed of a material with a lower thermal conductivity than water. Therefore, the second heat transfer suppressing member 37 may be formed of the same material as the heat transfer suppressing member 30. In this case, the thickness of the heat transfer suppressing member 30 shown in FIG. 6 can be set to about half the thickness of the heat transfer suppressing member 30 shown in FIG. 2 and FIG. 3.

The second heat transfer suppressing member 37 is composed of a member with a C-shaped cross section, whose inner diameter is slightly smaller than or equal to the outer diameter of the heat transfer suppressing member 30, and in which slits 37a are formed along the entire longitudinal direction. The slits 37a of the second heat transfer suppressing member 37 are offset in the circumferential direction relative to the slits 32a of the heat transfer suppressing member 30. Therefore, the slits 32a of the heat transfer suppressing member 30 are covered by the second heat transfer suppressing member 37.

When the second heat transfer suppression member 37 is provided, it is possible to suppress the intrusion of water through the slit 32a. In other words, it is possible to simultaneously facilitate the installation of the heat transfer suppression member 30 and prevent the intrusion of water.

The heat transfer suppression member 30 may be composed of a plurality of divided members 39 arranged in the extension direction of the heat transfer tube 14, as shown in FIG. 7. That is, the heat transfer suppression member 30 is attached to the heat transfer tube 14 by arranging the plurality of divided members 39 on the heat transfer tube 14. In this case, a second heat transfer suppression member 41 is provided so as to cover the space between adjacent divided members 39. The second heat transfer suppression member 41 is formed of a material having a lower thermal conductivity than water. Therefore, the second heat transfer suppression member 41 may be made of the same material as the heat transfer suppression member 30. A plurality of second heat transfer suppression members 41 are also arranged. The contact positions of adjacent divided members 39 and the contact positions of adjacent second heat transfer suppression members 41 are shifted. Therefore, even if a gap is formed between adjacent divided members 39, the gap is covered by the second heat transfer suppression member 41.

In this embodiment, the heat transfer suppression member 30 can be attached to the heat transfer tube 14 by arranging multiple divided members 39 in the extension direction of the heat transfer tube 14. Therefore, even if the heat transfer tube 14 is very long, there is no need to prepare a very long integrated heat transfer suppression member 30, so the installation work of the heat transfer suppression member 30 can be prevented from becoming complicated. Moreover, because the second heat transfer suppression member 41 covers the gaps between the divided members 39, it is possible to prevent water from entering through these gaps.

Also, as shown in FIG. 8, one end of adjacent partition members 39 may cover the end of the other partition member 39. In this case, the gap between the ends of the partition members 39 can be covered without providing a second heat transfer suppression member 37.

In the configuration of FIG. 1, the water inlet port 21 is provided only on the inlet chamber 16 side of the shell 12, but this is not limited to the configuration. As shown in FIG. 9, the water inlet port 21 may be provided on the inlet chamber 16 side and the outlet chamber 18 side. In this case, the water outlet port 22 is located at the center position in the longitudinal direction of the shell 12. Even in this case, the heat transfer suppression member 30 is provided only on a part of the heat transfer tube 14 on the inlet chamber 16 side. Note that the baffle plate 25 may be provided or may be omitted as shown in FIG. 9.

In the configuration of FIG. 1, the heat transfer tube 14 is shown as a straight tube, but this is not limited thereto. As shown in FIG. 10, the heat transfer tube 14 may be a U-shaped tube. In this case, the inlet chamber 16 and the outlet chamber 18 are arranged adjacent to each other at one end side of the longitudinal direction of the shell 12. The outlet chamber 18 is arranged, for example, above the inlet chamber 16. The liquefied natural gas flows from the inlet chamber 16 into the lower straight pipe section 14a of the U-shaped tube. For this reason, the heat transfer suppression member 30 is provided in the lower straight pipe section 14a of the U-shaped tube. Since the liquefied natural gas begins to partially evaporate in the lower straight pipe section 14a of the U-shaped tube, the heat transfer suppression member 30 is arranged up to the middle position of the lower straight pipe section 14a.

As shown in FIG. 11, the vaporizer 10 may be provided with a natural gas heating section 43 in the shell 12 in addition to the heat transfer tube 14 (evaporation section) where the liquefied natural gas evaporates. In this case, a connecting tube 45 is connected to the outlet chamber 18, and this connecting tube 45 is connected to a connection chamber 47 that communicates with the heat transfer tubes that make up the heating section 43. The natural gas that flows through the connecting tube 45 flows into the heating section 43 (heat transfer tube) through the connection chamber 47, and is further heated in the heating section 43. The natural gas that flows through the heating section 43 flows out through the supply chamber 49 to an external pipe (not shown).

In the configuration shown in FIG. 1, the heat transfer tube 14 is a straight tube, but instead, the heat transfer tube 14 may be formed to meander as shown in FIG. 12. That is, the heat transfer tube 14 may have a plurality of straight tube sections 14b spaced apart vertically and a plurality of curved bend sections 14c arranged at the ends of the straight tube sections 14b, and may have a shape that extends vertically while meandering. The lowermost straight tube section 14b is connected to the inlet chamber 16, and the uppermost straight tube section 14b is connected to the outlet chamber 18.

In this case, the liquefied natural gas is introduced from the inlet chamber 16 into the straight pipe section 14b located at the lowest position among the multiple straight pipe sections 14b, and a part of the liquefied natural gas begins to evaporate in the straight pipe section 14b located at the lowest position. For this reason, the heat transfer suppression member 30 is attached to the straight pipe section 14b located at the lowest position. It is not necessary to attach the heat transfer suppression member 30 to the bend section 14c located at the lowest position. This is because, even if ice forms in the bend section 14c, it will not block the gap between adjacent heat transfer tubes 14.

When the heat transfer tube 14 is formed to meander, for example, as shown in Figures 13 and 14(a), multiple bends 14c arranged vertically at one end of the straight tube section 14b may be arranged in an alternatingly shifted position. The same applies to the other end. Specifically, the multiple bends 14c of the heat transfer tube 14 include a first bend 71 that is a bend that protrudes in the extension direction of the straight tube section 14b, and a second bend 72 that is a bend that recedes in the extension direction of the straight tube section 14b. The first bend 71 and the second bend 72 are arranged alternately in the vertical direction. Note that it is sufficient that at least one first bend 71 and one second bend 72 are included.

The first bend section 71 and the second bend section 72 are welded to the end of the straight pipe section 14b. The welded section 71a between the first bend section 71 and the straight pipe section 14b is located closer to the apex section 72c of the second bend section 72 (on the right side in Figures 13 and 14(a)) than the welded section 72a between the second bend section 72 and the straight pipe section 14b in the extension direction of the straight pipe section 14b. In addition, the welded section 71a between the first bend section 71 and the straight pipe section 14b may be located closer to the apex section 72c of the second bend section 72 than the inner curved surface section 72b of the second bend section 72 in the extension direction of the straight pipe section 14b. In addition, the welded portion 71a between the first bend portion 71 and the straight pipe portion 14b may be located further outward (away from the inner curved surface portion 72b, on the right side in Figures 13 and 14(a)) than the apex portion 72c of the second bend portion 72 in the extension direction of the straight pipe portion 14b. Alternatively, the welded portion 71a between the first bend portion 71 and the straight pipe portion 14b may be located between the apex portion 72c and the welded portion 72a of the second bend portion 72 in the extension direction of the straight pipe portion 14b.

One end of the heat transfer tube 14 may be connected to the inlet chamber 16, or alternatively, as shown in FIG. 13, it may be connected to an inflow header 75 that introduces liquefied natural gas into the multiple heat transfer tubes 14. The inflow header 75 is disposed within the shell 12 and is connected to an inflow pipe 76 that penetrates the shell 12. The liquefied natural gas flows into the inflow header 75 from outside the shell 12 through the inflow pipe 76. The heat transfer suppression member 30 is attached to the lowest straight pipe section 14b that is connected to the inflow header 75.

The other end of the heat transfer tube 14 may be connected to the outlet chamber 18, or alternatively, may be connected to an outlet header 77 that joins the natural gas obtained in the multiple heat transfer tubes 14. The outlet header 77 is disposed in the shell 12 and is connected to an outlet pipe 78 that passes through the shell 12. The natural gas in the outlet header 77 is discharged to the outside of the shell 12 through the outlet pipe 78. As shown in FIG. 13, the baffle plate 25 may be connected to one side of the shell 12 by a spacer 79 and a tie rod 80.

14(a) and 14(b), the heat transfer tubes 14 arranged in the horizontal direction are arranged so that the bends 14c are alternately shifted. Specifically, the first heat transfer tube 61, the second heat transfer tube 62 adjacent to the first heat transfer tube 61, the third heat transfer tube 63 adjacent to the second heat transfer tube 62, and the fourth heat transfer tube 64 adjacent to the third heat transfer tube 63 will be described. In the first heat transfer tube 61 and the third heat transfer tube 63, the bends 14c at a certain height are in a protruding position in the extension direction of the straight tube portion 14b, and in the second heat transfer tube 62 and the fourth heat transfer tube 64, the bends 14c at the same height are in a recessed position in the extension direction of the straight tube portion 14b. Therefore, when viewed in the horizontal direction, the heat transfer tubes 14 with the protruding bends 14c and the heat transfer tubes 14 with the recessed bends 14c are arranged alternately. For example, the bend 14c (adjacent first bend) of the second heat transfer tube 62 (adjacent heat transfer tube) located next to the first bend 71 of the first heat transfer tube 61 becomes the second bend 72 located in a recessed position. Also, the bend 14c (adjacent second bend) of the second heat transfer tube 62 located next to the second bend 72 of the first heat transfer tube 61 becomes the first bend 71 located in a protruding position. The same relationship exists between the second heat transfer tube 62 and the third heat transfer tube 63, and also between the third heat transfer tube 63 and the fourth heat transfer tube 64. The second heat transfer tube 62 is adjacent to the first heat transfer tube 61, so it can be said to be an adjacent heat transfer tube to the first heat transfer tube 61. On the other hand, the first heat transfer tube 61 is adjacent to the second heat transfer tube 62, so it can be said to be an adjacent heat transfer tube to the second heat transfer tube 62.

A second bend section 72 of the first heat transfer tube 61 is disposed above and below the first bend section 71 of the first heat transfer tube 61. A first bend section 71 (adjacent second bend section) of the second heat transfer tube 62 is disposed next to each second bend section 72. In other words, in both the vertical and horizontal directions, the protruding bend section 14c (first bend section 71) and the recessed bend section 14c (second bend section 72) are arranged alternately. Note that the bend section 14c is configured as a short radius bend, but may be configured as a long radius bend.

The welded portion 71a between the first bend portion 71 and the straight pipe portion 14b in the first heat transfer tube 61 is disposed at a position protruding from the welded portion 72a between the adjacent first bend portion (second bend portion 72) and the straight pipe portion 14b in the second heat transfer tube 62 toward the apex portion 72c of the adjacent first bend portion in the extension direction of the straight pipe portion 14b (the right side in Figures 14 (a) and (b)). Also, the welded portion 71a of the first bend portion 71 in the first heat transfer tube 61 is disposed at a position protruding from the inner curved surface portion 72b of the adjacent first bend portion (second bend portion 72) in the second heat transfer tube 62 toward the apex portion 72c of the adjacent first bend portion in the extension direction of the straight pipe portion 14b. The welded portion 71a of the first bend portion 71 in the first heat transfer tube 61 is disposed at a position corresponding to the position of the apex portion 72c of the adjacent first bend portion (second bend portion 72) in the second heat transfer tube 62 in the extension direction of the straight tube portion 14b. The welded portion 71a of the first bend portion 71 in the first heat transfer tube 61 may be disposed between the inner curved surface portion 72b of the second bend portion 72 in the second heat transfer tube 62 and the apex portion 72c of the bend portion 72 in the extension direction of the straight tube portion 14b, or may be disposed further outside (the side farther from the inner curved surface portion 72b, the right side in FIG. 14(a)) than the apex portion 72c of the bend portion 72.

In any of the heat transfer tubes 61 to 64 arranged horizontally, the welded portion (first pipe welded portion) 71a of the first bend portion 71 protrudes in the extension direction of the straight pipe portion 14b more than the welded portion (second pipe welded portion) of the second bend portion 72 of the adjacent heat transfer tube. For example, since the adjacent second bend portion in the second heat transfer tube 62 is the first bend portion 71, the welded portion 71a between the adjacent second bend portion and the straight pipe portion 14b is located at a position that protrudes more in the extension direction of the straight pipe portion 14b than the welded portion 72a between the adjacent first bend portion (second bend portion 72) and the straight pipe portion 14b.

A heat transfer suppression member 30 is attached to the lowest straight pipe section 14b of each of the first heat transfer tube 61 to the fourth heat transfer tube 64.

Second Embodiment
The first embodiment is a vaporizer 10 for liquefied natural gas, while the second embodiment is a cooling system 53 including the vaporizer 10. Specifically, as shown in FIG. 15, the cooling system 53 includes the vaporizer 10 and a cooler 55. The vaporizer 10 is the vaporizer 10 having any of the configurations described in the first embodiment. The cooler 55 is connected to the outlet port 22 of the vaporizer 10 through a pipe 56. The cooler 55 is configured as a heat exchanger that cools a predetermined object by water cooled by the liquefied natural gas. The object to be cooled by the cooler 55 can be selected according to the purpose, such as conditioned air or cold water used for indoor cooling, vegetable factories, cable pit cooling, and the like, and the intake air of a gas turbine.

In this cooling system 53, the water cooled by the liquefied natural gas in the carburetor 10 is used in the cooler 55 to cool the object to be cooled. Therefore, the cold energy of the liquefied natural gas can be used to cool the object to be cooled. Furthermore, the heat transfer suppression member 30 is provided in the carburetor 10 to suppress freezing of the water. This makes it possible to set the carburetor 10 so that the temperature of the water drawn out from within the carburetor 10 is lower. Therefore, the performance of the cooling system 53 can be improved.

Note that the description of the other configurations, actions, and effects will be omitted, but the description of the first embodiment can be applied to the second embodiment.

REFERENCE SIGNS LIST 10 Vaporizer 12 Shell 14 Heat transfer tube 14a Straight tube section 14b Straight tube section 14c Bend section 16 Inlet chamber 18 Outlet chamber 30 Heat transfer suppressing member 32 Slit 37 Second heat transfer suppressing member 39 Dividing member 41 Second heat transfer suppressing member

Claims (16)

A shell having an inner space extending in one direction, into which water is introduced;
a heat transfer tube disposed in the inner space, into which a low-temperature liquefied gas is introduced and which heats the low-temperature liquefied gas by the water;
a heat transfer suppressing member formed of a material having a lower thermal conductivity than water,
The shell has an outer circumferential surface provided with the water inlet port and the water outlet port,
One end of the heat transfer tube, which is an inlet side of the low-temperature liquefied gas, is inserted into a partition wall arranged at one end of the inner space in the one direction,
the partition wall is provided so as to be located upstream in the flow direction of the low-temperature liquefied gas in the heat transfer tube with respect to the inlet port located upstream in the flow direction of the low-temperature liquefied gas,
The heat transfer suppression member covers a portion of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, and suppresses freezing of water even when no water flow occurs around the heat transfer tube. The heat transfer suppressing member is disposed over a region where the low-temperature liquefied gas starts to evaporate, or, when the low-temperature liquefied gas flows through the heat transfer tube in a state of a supercritical fluid, over a region from the introduction region of the low-temperature liquefied gas to a region where the low-temperature liquefied gas is heated without undergoing a phase change,
The low temperature liquefied gas vaporizer according to claim 1 , wherein the heat transfer tube is covered. The low-temperature liquefied gas vaporizer according to claim 1 or 2, wherein the heat transfer suppression member is made of a resin-based material, a glass-based material, a rubber-based material, or a ceramic-based material. The low-temperature liquefied gas vaporizer according to any one of claims 1 to 3, wherein the heat transfer suppression member is composed of a member having a C-shaped cross section, a pipe-shaped member, or two halves of a member. The low-temperature liquefied gas vaporizer according to any one of claims 1 to 4, wherein the heat transfer suppression member is attached to the heat transfer tube from the outside so as to be detachable from the heat transfer tube. the heat transfer suppressing member is configured with a member having a C-shaped cross section and a slit,
The low-temperature liquefied gas vaporizer according to claim 1 , further comprising a second heat-transfer suppressing member that covers the slits of the heat-transfer suppressing member. the heat transfer suppressing member is composed of a plurality of divided members arranged in an extension direction of the heat transfer tube,
6. The low-temperature liquefied gas vaporizer according to claim 1, further comprising a second heat transfer suppressing member that is made of a material having a lower thermal conductivity than water and that covers the space between the partition members. the heat transfer suppressing member is composed of a plurality of divided members arranged in an extension direction of the heat transfer tube,
6. The cryogenic liquefied gas vaporizer according to claim 1, wherein one end of each of adjacent divided members covers an end of the other divided member. A plurality of the heat transfer tubes are provided,
Each of the plurality of heat transfer tubes has a plurality of straight tube portions and a plurality of bent portions, and has a shape that extends vertically while meandering,
the low-temperature liquefied gas is introduced into a straight pipe section located at the lowermost position among the plurality of straight pipe sections,
2. The low-temperature liquefied gas vaporizer of claim 1, wherein the heat transfer suppression member is attached to the lowest straight tube section of each heat transfer tube, covering the heat transfer tube in a portion of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, while not being attached to the lowest bend section. Among the plurality of bends, the plurality of bends arranged in the vertical direction include at least one first bend and at least one second bend located at a position recessed from the first bend in the extension direction of the straight pipe portion, and the at least one first bend and the at least one second bend are arranged alternately,
The low-temperature liquefied gas vaporizer of claim 9, wherein a weld between the at least one first bend portion and a straight pipe portion protrudes in the extension direction of the straight pipe portion more than a weld between the at least one second bend portion and a straight pipe portion. The heat transfer tube may be disposed adjacent to the heat transfer tube in the inner space, and a low-temperature liquefied gas may be introduced into the heat transfer tube, and the low-temperature liquefied gas may be heated by the water.
The adjacent heat transfer tube has a plurality of straight tube portions and a plurality of bent portions, and has a shape that extends vertically while meandering,
the plurality of bends arranged in the vertical direction among the plurality of bends in the adjacent heat transfer tubes include at least one adjacent first bend portion adjacent to the at least one first bend portion and at least one adjacent second bend portion adjacent to the at least one second bend portion, the at least one adjacent first bend portion and the at least one adjacent second bend portion are arranged alternately;
A low-temperature liquefied gas vaporizer as described in claim 10, wherein the welded portion between the at least one adjacent second bend portion and the straight pipe portion protrudes more in the extension direction of the straight pipe portion than the welded portion between the at least one adjacent first bend portion and the straight pipe portion, and protrudes more in the extension direction of the straight pipe portion than the welded portion between the at least one second bend portion and the straight pipe portion. an inlet chamber into which the low-temperature liquefied gas flows;
an outlet chamber into which gas vaporized from the low-temperature liquefied gas in the heat transfer tube flows,
The heat transfer tube is formed of a straight tube that linearly connects the inlet chamber and the outlet chamber,
9. The low-temperature liquefied gas vaporizer according to claim 1, wherein the heat transfer suppressing member covers a predetermined area of the heat transfer tube from the inlet chamber. A plurality of the heat transfer tubes are provided,
Each of the plurality of heat transfer tubes is constituted by a U-shaped tube,
The low-temperature liquefied gas is introduced into a lower straight tube portion of the U-shaped tube,
2. The low-temperature liquefied gas vaporizer of claim 1, wherein the heat transfer suppression member covers the lower straight tube portion of the U-shaped tube in each heat transfer tube, thereby covering the heat transfer tube in a part of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, but is not attached to the bend portion of the U-shaped tube. an inlet chamber into which the low-temperature liquefied gas flows;
an outlet chamber into which gas vaporized from the low-temperature liquefied gas in the heat transfer tube flows,
9. The cryogenic liquefied gas vaporizer of claim 1, wherein the inlet port is disposed in the shell at a position adjacent to the inlet chamber. A vaporizer according to any one of claims 1 to 14;
a cooler into which water cooled by the low-temperature liquefied gas in the vaporizer is introduced. A shell having an inner space extending in one direction, into which water is introduced;
a heat transfer tube disposed in the inner space, into which a low-temperature liquefied gas is introduced and which heats the low-temperature liquefied gas by the water;
The shell has an outer circumferential surface provided with the water inlet port and the water outlet port,
One end of the heat transfer tube, which is an inlet side of the low-temperature liquefied gas, is inserted into a partition wall arranged at one end of the inner space in the one direction,
The partition wall is disposed upstream of the inlet port in a flow direction of the low-temperature liquefied gas in the heat transfer tube, the inlet port being located upstream of the flow direction of the low-temperature liquefied gas,
A method for suppressing icing in an evaporator, comprising attaching a heat transfer suppression member formed of a material having a lower thermal conductivity than water to the outer surface of a portion of the heat transfer tube including the introduction portion of the low-temperature liquefied gas, thereby suppressing freezing of water even when no water flow occurs around the heat transfer tube.

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