JP5301372B2 - Liquefied gas vaporizer - Google Patents

Description

  The present invention relates to a vaporizer that vaporizes liquefied gas such as liquefied natural gas (LNG), liquid hydrogen, liquid oxygen, liquid nitrogen and the like with a heating fluid such as seawater and fresh water. More specifically, the present invention relates to a technique for controlling the flow of refrigerant flowing around the heat transfer tube of a vaporizer.

  A conventional LNG vaporizer, which is generally used as a liquefied gas vaporizer, has a structure in which a plurality of finned heat transfer tubes made of aluminum alloy are arranged vertically and the upper and lower ends are connected to each other by an upper header and a lower header. Is distributed to each heat transfer tube, and the inside of the heat transfer tube flows upward, while the outside of the heat transfer tube is configured to continuously supply seawater so as to flow down along the surface of the heat transfer tube (Patent Document) 1, 2). A large number of heat transfer tubes are arranged in a straight line with a certain distance from each other between adjacent heat transfer tubes, and are covered with a curtain of seawater that flows down along the outer peripheral surface of the heat transfer tubes. As a result, the LNG of about −160 ° C. at the time of entering the lower end of the heat transfer tube is vaporized by the temperature of the seawater flowing down along the outer surface of the heat transfer tube while rising in the heat transfer tube, and is collected in the upper header of the upper end of the heat transfer tube. It is almost vaporized at the time.

  On the other hand, seawater temperature varies greatly depending on the season. For example, the temperature is about 25 ° C. in summer and about 10 ° C. in winter. For this reason, in winter, seawater may freeze in the range of about 1 m at the lower end of the heat transfer tube. At this time, ice (heat conductivity: about 2.2 W / mK) is lower in heat conductivity than heat transfer tubes made of aluminum alloy (heat conductivity: about 190 W / mK), so the vaporization performance of LNG is reduced. To do.

  Moreover, in the case of the cooling water vaporizers shown in Patent Documents 1 and 2, LNG is vaporized using the temperature of seawater, but a large amount of cold heat is used without effectively utilizing the temperature difference between LNG and seawater. Is unnecessarily dumped into the ocean, which is not preferable from the viewpoint of effective use of unused energy, and is also uneconomical in terms of heat economy.

  Therefore, the present inventors, in a liquefied gas vaporizer using a liquid such as seawater or water as a heating medium, prevent freezing of water at the lower end of the heat transfer tube and use the temperature difference between the liquefied gas and the heating fluid as electric power. For the purpose of conversion and effective use, a part near the lower end of the finned heat transfer tube, for example, a thermoelectric conversion module is provided on the surface of the heat transfer tube in the range of about 1 m at the lower end of the heat transfer tube, and the temperature of the liquefied gas and seawater It was previously proposed to generate power due to the difference and prevent freezing of seawater (application number 2008-062949, filed on March 12, 2008). Here, the connection part between the heat transfer tube portion having a rectangular cross section for attaching the thermoelectric conversion module and the finned heat transfer tube above it has a sudden shape change, so it vigorously moves along the surface of the heat transfer tube. The falling water peels off from the surface of the heat transfer tube and scatters outside. In order to prevent this water flow from scattering, a streamlined transition part that continuously connects both contour shapes without any step to the connection part of the heat transfer tube part with the thermoelectric conversion module and the heat transfer pipe with fins above it. It is proposed to intervene (called a streamlined transition).

JP-A-5-16496 JP 7-339459 A

  However, in an actual LNG vaporizer, in order to suppress an increase in equipment size, a large number of vertically arranged heat transfer tubes are required to be arranged with the gap between adjacent heat transfer tubes as narrow as possible. In the heat transfer tube portion with the thermoelectric conversion module that swells further in the diameter direction than the heat transfer tube with fins, the gap between adjacent heat transfer tubes tends to be narrower. For this reason, as shown in FIG. 1, when two streamlined transition parts are arranged at an arrangement pitch of an actual liquefied gas vaporizer, the interval between adjacent heat transfer tubes is narrow, and the water flowing between adjacent heat transfer tubes It has been proved by experiments and research by the present inventors that when the flow reaches the lower end of the streamlined transition portion, that is, when it reaches the heat transfer tube portion with the thermoelectric conversion module, it loses the escape place and scatters in the horizontal direction. In other words, when seawater flowing down the gap between adjacent heat transfer tubes flows down along the streamlined transition part, the lower end of the streamlined transition part becomes narrower than the gap between adjacent heat transfer pipes. It became clear that the flow of the seawater flowing along the surface that collides with each other and scattered so as to jump out between the adjacent streamlined transitions. And in the sea water which not only peels from each surface of the heat exchanger tube with a thermoelectric conversion module adjacent to each other but also the other surface adjacent to them by the sea water flowing between the adjacent heat transfer tubes splashes However, it will be peeled off from the surface of the heat transfer tube by being guided by the flow of scattered seawater. By this, the surface of the heat exchanger tube with a thermoelectric conversion module heated with seawater will decrease. In addition, for this reason, there is a problem that the temperature difference given to the thermoelectric conversion module is reduced, the power generation efficiency is lowered, and the cold heat of LNG cannot be effectively used.

  Accordingly, an object of the present invention is to prevent seawater flowing between adjacent heat transfer tubes from being scattered in a liquefied gas vaporizer using a liquid such as seawater or water as a heating medium.

  In order to achieve such an object, according to the first aspect of the present invention, the liquefied gas introduced from the lower end of the plurality of heat transfer tubes installed vertically and arranged close to each other is raised, while the heat transfer tube In the carburetor having a structure in which the heating fluid flows down along the outer surface of the heat transfer tube on the outside, the heating fluid outside the heat transfer tube and the liquefied gas inside the heat transfer tube are partially or entirely near the lower end of the heat transfer tube. While installing the thermoelectric conversion module that performs the vaporization of the liquefied gas using the temperature difference and at the same time generates power with the thermoelectric conversion module, the heat transfer tube with the heat transfer surface exposed entirely and the heat transfer with the thermoelectric conversion module A streamlined transition part that continuously connects the contour shapes of the two heat transfer tubes without any step is arranged at the connection part with the heat pipe, and a knife edge is provided between the adjacent streamlined transition parts. There.

  Here, the knife edge is preferably provided with fins on the surface parallel to the flow.

  According to the first aspect of the present invention, the adjacent heat transfer tubes are formed by the action of the knife edge installed between the streamlined transition portion installed at the connection portion between the finned heat transfer tube and the heat transfer tube with the thermoelectric conversion module and the adjacent streamlined transition portion. The seawater that flows through the gap between the two flows along the streamlined transition, and at the same time is guided outward from between adjacent streamlined transitions by the knife edge, so the flow of seawater that flows along the opposite surface of the streamlined transition Will not collide with each other and will not scatter to the outside, and will flow down along the surface of each heat transfer tube with a thermoelectric conversion module.

  Therefore, since the temperature difference between the liquefied gas flowing inside the heat transfer tube and the heated fluid flowing outside is applied to the thermoelectric conversion module, power generation is possible simultaneously with vaporization of the liquefied gas. And since the temperature fall of the surface through which the heating fluid flows in the vicinity of the lower end of the heat exchanger tube where the presence of the thermoelectric conversion module is likely to freeze is prevented, freezing can be prevented. That is, according to the liquefied gas vaporizer of the present invention, it is possible to generate power without impairing the performance of the vaporizer.

  In addition, when fins parallel to the flow are provided on the surface of the knife edge, the water flowing down along the surface of the knife edge is distributed to the left and right, so that it is less likely to flow significantly biased to one of the heat transfer tubes with a thermoelectric conversion module. Become.

It is a perspective view which shows the situation which arranged two streamlined transition parts arrange | positioned in the connection part of the heat exchanger tube with the exposed heat transfer surface, and the heat exchanger tube with a thermoelectric conversion module in the liquefied gas vaporizer of this invention by the actual arrangement pitch. . It is a perspective view which shows one Example of a knife edge. It is a perspective view which shows the condition where the knife edge was attached between two adjacent streamlined transition parts from the upper left front slightly. It is a perspective view which shows the condition where the knife edge was attached between two adjacent streamlined transition parts from diagonally right above. Explanatory drawing which shows the flow condition of the water in a streamlined transition part when water is dropped along a heat exchanger tube in the test device which connected a heat exchanger tube with a fin and a heat exchanger tube with a thermoelectric conversion module with a streamlined transition part It is. In the enlarged view of FIG. 5, the flow condition of the water in the surface of the heat exchanger tube with a thermoelectric conversion module just under a streamline type transition part is shown. It is an enlarged view which shows the apparatus of FIG. 5 from a side surface, and shows the flow condition of the water on the surface of the heat exchanger tube with a thermoelectric conversion module just under a streamline type transition part. It is an enlarged view which shows the apparatus of FIG. 5 from the opposite side surface, and shows the flow condition of the water on the surface of the heat exchanger tube with a thermoelectric conversion module immediately under the streamline type transition part. In a test device in which a heat transfer tube with fins and a heat transfer tube with a thermoelectric conversion module are connected by a streamlined transition, and a knife edge is installed between two adjacent streamlined transitions, water was dropped along the heat transfer tube It is explanatory drawing which shows the flow condition of the water in the surface of the streamlined transition part and the heat exchanger tube with a thermoelectric conversion module immediately below from the front side. It is a perspective view which shows the apparatus of FIG. 9 from diagonally right upper, and shows the flow condition of the water in a streamlined transition part. It is a figure which shows the apparatus of FIG. 9 from a side surface, and shows the flow condition of the water on the surface of the heat exchanger tube with a thermoelectric conversion module just under a streamline type transition part. It is a perspective view which shows the apparatus of FIG. 9 from diagonally left upper, and shows the flow condition of the water on the surface of the heat exchanger tube with a thermoelectric conversion module just under a streamline type transition part. It is explanatory drawing which shows schematic structure of the heat exchanger tube of a liquefied gas vaporizer. It is a perspective view which shows the relationship between a streamlined transition part and a knife edge. It is an axis perpendicular sectional view of a heat exchanger tube with a thermoelectric conversion module. It is an axial sectional view of a heat exchanger tube with a thermoelectric conversion module. It is a longitudinal cross-sectional view which shows an example of a waterproof thermoelectric conversion module.

  Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings. In the following description, for the sake of simplification, only water is shown as a representative of a heated fluid (seawater, water, etc.), but the present invention is not limited to this, as long as the temperature is higher than that of the liquefied gas. , Hot water and other liquids, and two-layer flow of water vapor and hot water. Of course, it may be freshly taken seawater, river water or tap water, but the higher the temperature of the heated fluid, the better the vaporization performance and power generation performance. But you can.

  FIGS. 1 to 4 and FIGS. 13 to 17 show an embodiment in which the liquefied gas vaporizer of the present invention is applied to a LNG (liquefied natural gas) vaporizer. In this liquefied gas vaporizer, a thermoelectric conversion module 7 is installed on a part or all surfaces (in the axial direction or surface) near at least the lower end (region indicated by reference numeral 5) of the heat transfer tube 1 installed vertically, The temperature difference between the heating fluid 27 outside the heat transfer tube 1 and the inside liquefied gas 26 is utilized to vaporize the liquefied gas 26 and at the same time, the thermoelectric conversion module 7 generates power. Here, the thermoelectric conversion module 7 is preferably provided at least in the region 5 near the lower end of the heat transfer tube 1 where water is likely to freeze, considering the coexistence of vaporization of liquefied gas and power generation. However, this does not mean that the thermoelectric conversion module 7 must be installed immediately from the lower end of the heat transfer tube 1. And in the area | region 5 near the lower end of the heat exchanger tube 1, you may make it provide the thermoelectric conversion module 7 in the whole region of the pipe-axis direction, but depending on the case, the area | region which provides the thermoelectric conversion module 7, and the thermoelectric conversion module 7 are provided. Instead, a region where the heat transfer tube 1 is directly exposed may be provided. The thermoelectric conversion module 7 is, for example, a surface excluding a surface facing a heat transfer tube adjacent to a heat transfer tube having a rectangular cross section, specifically two surfaces facing each other on the front side and the back side of the heat transfer tube group forming a row. (Three surfaces in the tubes at both ends of the tube row), and in some cases, it is preferably provided on either the front surface or the back surface. Of course, the thermoelectric conversion module 7 may be formed in an arc shape, and in that case, it is preferably provided on a surface excluding the surface facing the other adjacent heat transfer tube of the cylindrical heat transfer tube. In some cases, the thermoelectric conversion module 7 may be installed in an intermediate region above the lower end region 5 of the heat transfer tube 1 or the like. That is, the thermoelectric conversion module 7 is preferably installed in at least a part or the whole of the region 5 near the lower end of the heat transfer tube 1, but is not particularly limited thereto. In an actual liquefied gas vaporizer, a large number of heat transfer tubes are arranged horizontally and connected by upper and lower headers 2 and 3, but in the description of this embodiment, one or two tubes are shown for convenience of explanation. To do. In addition, as a method for supplying the heating fluid 27, an example in which the heating fluid 27 flows down from the vicinity of the upper end of the heat transfer tube 1 along the outer surface by overflowing the water supply rod 28 is described for convenience of explanation. Moreover, the code | symbol 29 is the seawater which fell.

  According to the analysis by the present inventors, the LNG 26 flows upward inside the finned heat transfer tube made of aluminum alloy and the seawater 27 flows outside along the heat transfer tube surface (called an open rack type vaporizer). In the winter, for example, in the winter season, it was found that the bottom end portion of the 6-m finned heat transfer tube is about 1 to 2 m, and the maximum icing thickness is about 9 mm. This icing causes the ability to vaporize to be impaired. Therefore, a conventional LNG vaporizer that is actually in practical use is generally a finned heat transfer tube 4 made of an aluminum alloy having a total length of 6 to 8 m, and therefore a part of the lower end thereof, for example, about 1 to 2 m. Is preferably replaced in series with a heat transfer tube 5 with a thermoelectric conversion module having a rectangular cross section. In this case, the total length as the heat transfer tube does not change, but of course, the total length as the heat transfer tube may be changed.

  In the present embodiment, the heat transfer tube 1 includes a finned heat transfer tube 4 having a circular cross section provided radially with heat transfer fins 4a on the outer peripheral surface of the tube, and a thermoelectric conversion module on the outer peripheral surface as shown in FIGS. A heat transfer tube 5 with a thermoelectric conversion module having a rectangular cross section is connected in series. The finned heat transfer tube 4 and the thermoelectric conversion module-equipped heat transfer tube 5 are not limited to specific materials, but it is preferable to use an aluminum alloy or the like in consideration of thermal conductivity, corrosion resistance, and the like. Therefore, for example, inert gas arc welding (TIG welding) is used for the connection, and welding is performed without a step.

  The heat transfer tube 5 with a thermoelectric conversion module has a rectangular outer cross-sectional shape, and is provided with a thermoelectric conversion module 7 on any surface, and a heat insulating material 8 is disposed around each thermoelectric conversion module 7 to provide unevenness. It is provided so as to form a surface having no surface. By arranging the heat insulating material 8 so as to be filled between the thermoelectric conversion modules 7, there is no unevenness on the surface, and water can flow down along the surface of the thermoelectric conversion module 7 without being peeled off. it can. In the case of this embodiment, as shown in FIGS. 15 and 16, among the heat transfer tubes 5 having a rectangular contour shape, the thermoelectric conversion modules 7 are provided on the two opposite surfaces, and the heat insulating material 8 is attached to the remaining two surfaces. Thus, the temperature difference between the inside and outside of the heat transfer tube 5 is mainly provided to the thermoelectric conversion module 7 to generate power. The thermoelectric conversion module 7 is fixed to the heat transfer tube 5 with screws 9 and both are in close contact with each other.

  Moreover, as shown in FIG. 16, the heat insulating material 8 which prevents the short circuit of heat is installed also in the axial direction (longitudinal direction) gap between the thermoelectric conversion module 7 and the thermoelectric conversion module 7. Thereby, the temperature difference between the inside and outside of the heat transfer tube 5 is effectively given to the thermoelectric conversion module 7 so that the cold heat of the liquefied natural gas 26 does not wastefully flow into the seawater 27. In addition to the heat insulating performance, the heat insulating material 8 is required to have durability against the extremely low temperature of the liquefied gas, corrosion resistance against water and other heating fluids, water resistance, and the like. Therefore, it is preferable to use wood or resin that has been subjected to waterproofing treatment. Further, the heat insulating material 8 has a role of eliminating a step from the surface of the thermoelectric conversion module 7 and preventing separation of water, and simultaneously holding a cable of the thermoelectric conversion module 7.

  Further, the thermoelectric conversion module 7 is preferably sealed in a case made of a corrosion-resistant material or a corrosion-resistant coating with respect to the heating fluid 27 to be contacted, such as seawater, or a resin, in order to prevent water from entering. Such a thermoelectric conversion module 7 can be easily realized by, for example, a case-sealed thermoelectric conversion module disclosed in JP-A-2006-49872. For example, as shown in FIG. 17, the thermoelectric conversion module 7 seals at least a pair of thermoelectric semiconductors 15 in an airtight case 20, and includes a heating side electrode part 16, a cooling side electrode part 17, and each electrode part 16, 17. A heating plate 20a and a cooling plate 19 that respectively cover the heat receiving portion are provided, and are placed between the heating side heat receiving surface and the cooling side heat radiation surface of the thermoelectric semiconductor 15 through the heating plate 20a and the cooling plate 19, respectively. It generates electricity by temperature difference. This thermoelectric conversion module 7 is provided at least between the heating plate 20a and the heating side electrode portion 16 with a sliding material 18 such as a thermal conductive sheet material or a thermal conductive grease made of a material having a low friction coefficient. The thermal connection between the heating plate 20a and the heating side electrode portion 16 is achieved with the sliding member 18 interposed therebetween. The cold-side electrode portion 17 is bonded to the cooling plate 19 with an electrically insulating adhesive 21 and bonded to the semiconductor 15 with a conductive adhesive 22. Moreover, the heating side electrode part 16 contacts the heating plate 20a through the sliding material 18 by using a functionally gradient material (FGM compliant pad) having an electrode layer and an electrical insulating layer, and the conductive adhesive 22 Some of them are bonded to the semiconductor 15. However, the structure of the thermoelectric conversion module is not limited to this. In addition, two electrodes protrude from each thermoelectric conversion module. The airtight case 20 is made of a material having excellent thermal conductivity and excellent corrosion resistance, such as an aluminum alloy, and is integrated by joining the high-rigidity cooling plate 19 by welding, an adhesive, or brazing. Has been. Further, the case 20 is provided with a pair of conductive portions 24 penetrating through, for example, the side surface thereof via an electrical insulator 23, and is connected to an electrode portion inside the case via a lead wire 25. An electrical circuit is configured by connecting the modules in series with each other using this electrode. Of course, the connection part of an electrode and an electric wire needs waterproofing measures so that it may not get wet with water. Also, the wire itself needs to be waterproofed. In the present embodiment that uses the thermoelectric conversion module enclosed in the case, the above-described heat insulating material is not particularly required to be electrically insulating because it is in an electrically insulated state.

  The connecting portion 10 between the finned heat transfer tube 4 and the thermoelectric conversion module-attached heat transfer tube 5 has a streamlined transition portion 14 that continuously connects the contour shapes of the finned heat transfer tube 4 and the thermoelectric conversion module-equipped heat transfer tube 5 without a step. Has been placed. In the case of this embodiment, as shown in FIG. 1, the streamlined transition portion 14 has a rectangular tube shape in which the lower end side forms a rectangular cross section according to the contour shape of the heat transfer tube 5 with the thermoelectric conversion module, and the upper end side has fins. It has a cylindrical shape with the same diameter and fin shape as the heat transfer tube 4, and is configured in a substantially truncated pyramid streamline shape in which the shape between both ends is continuously connected without a step. Here, since the fin 14a is formed on the upper end side, the groove gradually becomes shallower as the contour shape changes from a circular contour to a larger rectangular contour, and the fin 14a has a fin in the rectangular tube-shaped portion of the rectangular cross section. Is provided to disappear. And the lower end of the heat exchanger tube 4 with a fin and the upper end of the heat exchanger tube 5 with a thermoelectric conversion module are joined by welding or screwing in the state fitted to the streamlined transition part 14 (joint joint), respectively. The streamlined transition portion 14 is preferably formed of a material having excellent thermal conductivity and corrosion resistance, such as an aluminum alloy.

  The above-mentioned streamlined transition section 14 causes the flow of water flowing down along the outer surface of the finned heat transfer tube 4 to flow outside without being scattered or separated, and along the outer surface of the heat transfer tube 5 with the thermoelectric conversion module. Guide it to flow down. As a result, the heated fluid / seawater 27 flowing down vigorously along the outer surface of the finned heat transfer tube 4 undergoes a sudden shape change in the connection portion 10 between the finned heat transfer tube 4 and the heat transfer tube 5 with the thermoelectric conversion module having a rectangular cross section. Therefore, it is guided to flow down along the outer surface of the heat transfer tube 5 with the thermoelectric conversion module without being scattered outside or separated from the outer surface, and flows along the surface of the thermoelectric conversion module 7.

  Also, as shown in FIGS. 3 and 4, there is a knife edge 11 that fills the gap between the adjacent streamlined transition parts 14 between the streamlined transition parts 14 arranged in a plurality of rows at an actual arrangement pitch. Installed. An example of the knife edge 11 is shown in FIG. In the case of the present embodiment implemented as an LNG vaporizer, the knife edge 11 needs durability of the liquefied gas to extremely low temperatures, corrosion resistance and water resistance against seawater, etc., for example, aluminum alloy, cold-resistant plastic, waterproof treatment Use of applied wood and resin is suitable. The knife edge 11 forms a linear tip 11a serving as a diversion trough across between the adjacent streamlined transitions 14 at the upper end, and fills the space between the adjacent streamlined transitions 14 at the lower end 11b and is a streamlined transition. An inclined surface 11c having an I-shape that slightly covers the edges of the front and back surfaces of the portion 14, and a shape between the upper end 11a and the lower end 11b that is substantially the same as the contour shape of the streamlined transition portion 14 viewed from the side. Is forming. In the case of the present embodiment, there is a tip 11a serving as a water divide in the middle of the streamlined transition portion 14 in the depth direction, and an inclined surface 11c having the same width that branches from the front side to the back side is formed. And between each slope 11c of a front side and a back side is supported by the thick partition 11d which fills the gap | interval between the adjacent streamlined transition parts 14 in the position of the lower end of a streamlined transition part. Accordingly, the seawater flowing down between the adjacent streamlined transition portions 14 is divided into two parts in the front and rear at the tip 11a of the knife edge 11, and the opposing surfaces of the adjacent streamlined transition portions 14 and the inclined surfaces 11c of the knife edge 11 therebetween. Is guided to the surface of the heat transfer tube 5 with the thermoelectric conversion module, and then flows down along the surface of the heat transfer tube 5 with the thermoelectric conversion module.

  The knife edge 11 has fins 13 in the lower region parallel to the flow. The fin 13 distributes the water flowing down along the surface of the knife edge to the left and right to prevent the water from flowing significantly biased to one of the heat transfer tubes with the thermoelectric conversion module. Therefore, when the heat transfer tube pitch is wide or the amount of water flowing down the gap between the adjacent streamlined transition portions 14 is small, there is a case where it is not necessary to provide the fins 13 because a biased flow hardly occurs.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, the outer shape of the heat transfer tube 5 with the thermoelectric conversion module is selected as one suitable for closely attaching the plate-shaped thermoelectric conversion module 7, and the shape as the heat transfer tube 5 with the thermoelectric conversion module 7 Is not necessarily limited to the rectangular shape. For example, in the case of using a curved plate-like thermoelectric conversion module, it is possible to form a cross-sectional shape adapted to this, that is, a circular tube. In this case, according to the external appearance of the thermoelectric conversion module, the shape of the streamlined transition portion 14 is also configured in a substantially truncated cone streamline. The shape of the knife edge 11 is also provided with a slope that forms a curve corresponding thereto, and the seawater flowing down between the adjacent streamlined transition portions 14 is divided into two at the front and rear at the tip 11a of the knife edge 11, and the adjacent streamlined transition portion 14 are guided to the front surface or the back surface of the heat transfer tube 5 with the thermoelectric conversion module by being guided by the respective inclined surfaces 11c of the knife edge 11 between them and flowing down to the surface of the heat transfer tube 5 with the thermoelectric conversion module. It is allowed to flow down along the surface.

  In the present embodiment, the heat transfer tubes having a rectangular cross section are arranged in the lower part of the heat transfer tube, and the streamlined transition portion for connecting the heat transfer tubes to the circular finned heat transfer tubes is mainly described. However, the present invention is not particularly limited to this, and is effective when heat transfer tubes having a rectangular cross section with a step are arranged side by side regardless of location.

  In order to confirm the behavior in the streamlined transition part of water falling along the heat transfer tube, the streamlined transition part 14 shown in FIG. 1 is arranged at the connection between the heat transfer tube 4 with fins and the heat transfer tube 5 with thermoelectric conversion module. A fluid experiment was performed to compare the situation in which two heat tubes 1 were arranged at an actual arrangement pitch and the situation in which a knife edge was provided between the streamlined transition portions 14 of the two heat transfer tubes. In the experiment, tap water was used instead of seawater, and the water 6 was dropped after covering the transparent pipe 12 so that the water 6 supplied via the funnel-shaped water supply hose would not scatter.

  Here, the finned heat transfer tube 4 used in the experiment has a circular shape with an outer diameter of 35 mm, an inner diameter of 23 mm, and a wall thickness of 6 mm, and is provided with 10 fins in parallel with a base portion thickness of about 4 mm and a height of 8 mm. (Patent No. 3439644). On the other hand, a 50 mm square rectangular heat transfer tube (inner diameter 23 mm) was used for the heat transfer tube 5 with the thermoelectric conversion module. In this experiment, only six thermoelectric conversion modules 7 of about 50 mm square were installed on one side in this experiment, and the remaining two surfaces were attached with waterproofing wood as a heat insulating material 8 with screws. Further, a waterproofed wood 8 was also stuck between the upper and lower thermoelectric conversion modules 7 with screws. Thereby, it was set as the structure where the thermoelectric conversion module was embedded so that it might become flush | planar between the wooden pieces as the heat insulating material 8. FIG. Furthermore, the arrangement pitch of the heat transfer tubes was 60 mm, and the height of the streamlined transition portion 11 was 200 mm. The same as the one (comparative example 1) in which the streamlined transition portion 14 is connected to the heat transfer tube 4 with fins made of aluminum alloy having a length of 3 m and the heat transfer tube 5 with thermoelectric conversion modules made of aluminum alloy having a length of 1 m. A configuration (Example 1) in which a knife edge 11 was interposed in a heat transfer tube having a configuration was compared. In this experiment, since only water is allowed to flow out of the heat transfer tube without flowing LNG, the knife edge 11 having the structure shown in FIG. 2 is adopted, as shown in FIG. 3 and FIG. Attached between the streamlined transitions 14.

  As a result of this experiment, as shown in FIGS. 5 to 8, with only the streamlined transition part 14, the water 6 that has fallen into the space between the two streamlined transition parts 14 is near the lower end of the streamlined transition part 14. I lost the escape and confirmed that it was scattered laterally.

  On the other hand, when the knife edge 11 is installed between the streamlined transition parts 14, as shown in FIGS. 9 to 12, the water 6 that has fallen into the space between the two streamlined transition parts 14 is a knife. It was confirmed that due to the rectification effect of the edge 11, it flowed down in close contact with the rectangular heat transfer tube with thermoelectric conversion module 5 without peeling.

DESCRIPTION OF SYMBOLS 1 Heat transfer tube 4 Heat transfer tube with fin 5 Heat transfer tube with thermoelectric conversion module 7 Thermoelectric conversion module 8 Heat insulating material 10 Connection part of heat transfer tube with fin and thermoelectric conversion module 11 Knife edge 14 Streamlined transition part 26 Liquefied gas (liquefaction) Natural gas)
27 Heating fluid (seawater)

Claims (2)

A structure in which the liquefied gas introduced from the lower end is raised inside the plurality of heat transfer tubes installed vertically and arranged close to each other, while the heating fluid flows down along the outer surface of the heat transfer tubes outside the heat transfer tubes In the carburetor, the liquefied gas is vaporized by utilizing a temperature difference between the heated fluid outside the heat transfer tube and the liquefied gas inside at least a part of or near the lower end of the heat transfer tube. While installing the thermoelectric conversion module that generates power with the thermoelectric conversion module, the contour shape of both heat transfer tubes is stepped at the connection between the heat transfer tube with the heat transfer surface exposed entirely and the heat transfer tube with the thermoelectric conversion module. A liquefied gas vaporizer in which a streamlined transition portion that is continuously connected is disposed and a knife edge is provided between the adjacent streamlined transition portions. The liquefied gas vaporizer according to claim 1, wherein the knife edge has fins parallel to the flow.