JP5789386B2 - Low temperature liquefied gas vaporizer - Google Patents

Description

The present invention relates to a vaporizer for vaporizing a low-temperature liquefied gas such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), or liquid nitrogen (LN ₂ ) by heat exchange with a heat medium such as seawater.

  Conventionally, the thing of patent document 1 is known as a vaporizer (ORV) which heat-exchanges liquefied natural gas (LNG) with seawater, and vaporizes it.

  As shown in FIG. 13, this vaporizer is vaporized in a plurality of vaporized pipe blocks 102, distribution pipes 104 that distribute liquefied natural gas (low-temperature liquefied gas) to the vaporized pipe blocks 102, and vaporized pipe blocks 102. And a collecting pipe 106 for collecting liquefied natural gas (natural gas).

  Each vaporization pipe block 102 includes a plurality of vaporization pipe panels 108, a supply-side manifold 110 that distributes the liquefied natural gas from the distribution pipe 104 to each vaporization pipe panel 108, and the liquefied natural gas vaporized in each vaporization pipe panel 108. And a delivery-side manifold 112 that collects and feeds them to the collecting pipe 106. The plurality of vaporization tube panels 108 are arranged in a direction perpendicular to the panel surface in a posture parallel to each other. Each supply side manifold 110 is connected to the distribution pipe 104, and each delivery side manifold 112 is connected to the collecting pipe 106.

  The vaporization tube panel 108 includes a plurality of vaporization tubes (heat transfer tubes) 114 arranged on a vertical surface in parallel postures, and a supply-side header 116 that distributes liquefied natural gas from the supply-side manifold 110 to the vaporization tubes 114. And a delivery-side header 118 that collects the liquefied natural gas vaporized in each vaporization pipe 114 and delivers it to the delivery-side manifold 112. The supply side header 116 is connected to the lower end portion of each vaporization pipe 114 included in one vaporization pipe panel 108 and the supply side manifold 110. The delivery side header 118 is connected to the upper end portion of each vaporization pipe 114 included in one vaporization pipe panel 108 and the delivery side manifold 112.

  In such a vaporizer 100, the liquefied natural gas is vaporized by heat exchange between the liquefied natural gas flowing in the vaporization pipe 114 and seawater flowing down the surface of each vaporization pipe panel 108. Specifically, the liquefied natural gas supplied to the distribution pipe 104 is distributed to each vaporization pipe block 102 by the distribution pipe 104, and the vaporization pipe is supplied from the lower end portion of each vaporization pipe 114 through the supply side manifold 110 and the supply side header 116. 114 is supplied. The liquefied natural gas flows in the vaporization pipe 114 from the lower end to the upper end of the vaporization pipe 114. At that time, the liquefied natural gas is vaporized by exchanging heat with seawater flowing along the outer peripheral surface of the vaporized pipe 114 through the tube wall. The liquefied natural gas vaporized in each vaporizing pipe 114, that is, natural gas, is collected in the collecting pipe 106 via the sending side header 118 and the sending side manifold 112, and then connected to the collecting pipe 106 (not shown). ) Is sent to the consumption area.

  Further, the vaporizer 100 suppresses icing on the outer surface of the lower part of the vaporization tube 114 and secures sufficient heat transfer performance to efficiently vaporize the liquefied natural gas. It has a double tube structure provided with a heat tube 120. Specifically, as shown in FIGS. 14A and 14B, an internal heat transfer tube 120 is provided inside a vaporization tube 114 extending from the supply-side header 116. The inner heat transfer tube 120 extends along the vaporization tube 114 and has a length shorter than that of the vaporization tube 114. Further, the inner heat transfer tube 120 forms an outer space s1 between the inner heat transfer tube 120 and an inner space s2 inside thereof. The supply side header 116 supplies liquefied natural gas to the outer space s1 and the inner space s2. In such a vaporizer 100, the liquefied natural gas flowing in the outer space s1 has a smaller flow rate than the liquefied natural gas flowing in the inner space s2, and heat exchange with the outside of the vaporizer pipe 114 is easily performed, so that it is immediately vaporized. The vaporized liquefied natural gas (that is, natural gas) flows through the outer space s1. For this reason, the surface temperature of the vaporization tube 114 is higher than that of the vaporization tube in which the internal heat transfer tube 120 is not provided (vaporization tube in a state where the low-temperature liquefied gas before vaporization is flowing inside). Ice is suppressed. Further, when liquefied natural gas is vaporized in the outer space s1, forced convection boiling due to the temperature difference between the inner peripheral surface of the vaporization tube 114 and the outer peripheral surface of the inner heat transfer tube 120 is strengthened, and the heat transfer coefficient in the region is high. Become.

Japanese Patent Laid-Open No. 08-29075

  In the vaporizer 100, the pressure in each tube 104, 106, 110, 112, 114, 116, 118, the low-temperature liquefied gas (liquefied natural gas) flowing in each tube 104, 106, 110, 112, 114, 116, 118. Depending on the operating conditions such as the gas flow rate and temperature, vibration may occur in the vaporizer 100 and the piping system connected to the apparatus 100. This vibration generates high stress, accumulates metal fatigue or the like in each part constituting the vaporizer 100, and may cause damage or failure.

  In order to suppress this vibration, it is effective to increase the joint strength between the members in the vaporization tube block 102 and each vaporization tube panel 108 and increase the rigidity of the vaporization tube block 102 and each vaporization tube panel 108 as a whole. However, in this case, there is a problem that the thermal stress increases. Specifically, in the vaporizer 100, when a low-temperature (minus hundreds of degrees) liquefied gas is flowing in each pipe (during operation), and when the liquefied gas is not flowing and the entire apparatus is at room temperature There is a significant temperature difference from (when stopped). Therefore, the expansion and contraction (thermal expansion and contraction) of each member due to this temperature difference is intense, and if the members are firmly coupled to each other, excessive thermal stress due to the thermal expansion and contraction may occur, which may promote damage or failure.

  Therefore, in view of the above problems, the present invention is a vaporization apparatus in which an internal heat transfer tube is provided in a vaporization pipe, and when the low-temperature liquefied gas is vaporized, the vaporization apparatus or / and a piping system connected to the vaporization apparatus It is an object of the present invention to provide a low-temperature liquefied gas vaporizer that is unlikely to vibrate.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the vibration generated in the vaporizer and the like is caused by the low-temperature liquefied gas and the gas phase of the liquid phase in the vaporization tube near the upper end of the internal heat transfer tube 120. It was discovered that this was caused by periodic fluctuations in the boundary (interface) with the (vaporized) low-temperature liquefied gas. Details will be described below.

  In the vaporizer 100 described above, the low-temperature liquefied gas flowing in the outer space s1 flows in the vaporized state (gas phase) by heat from the outside of the vaporization tube 114, flows upward, and flows in the inner space s2. The gas flows upward while remaining in a liquid phase. The gas phase low-temperature liquefied gas (hereinafter also simply referred to as “gas”) g and the liquid-phase low-temperature liquefied gas (hereinafter also simply referred to as “liquefied gas”) l are the upper ends (tips) of the internal heat transfer tube 120. ) Join in the vicinity (merging area). In this merging region, periodic fluctuations at the interface between the gas g and the liquefied gas l occur. Specifically, the liquefied gas 1 supplied from the inter-vaporization pipe distribution pipe 116 to the outer space s1 is vaporized in the outer space s1, so that the gas g is low in density and higher in temperature than the liquefied gas l. When the boundary b is pushed up by the gas g above the tip of the inner heat transfer tube 120 (outside the outer space s1), as shown in FIG. 15A, the gas g and the liquefied gas l The area of the contact surface (interface) b is increased. Then, the gas g is cooled by heat exchange with the liquefied gas l and condensation occurs, and the interface b is drawn between the vaporization tube 114 and the internal heat transfer tube 120 (that is, in the outer space s1) by this condensation (FIG. 15 (B)). Thereafter, the interface b drawn into the outer space s1 starts to rise (see FIG. 15C). Such fluctuation of the interface b is repeated in the vaporizing tube 114. Here, the interface b between the gas g and the liquefied gas l is a boundary portion where the gas g that has passed through the outer space s1 and the liquefied gas l that has passed through the inner space s2 are in contact with each other, and is greater than or equal to a predetermined value. It is a site where a density difference (a density gradient greater than a predetermined value) is formed.

  When the periodic fluctuation of the boundary part (interface) b between the gas g and the liquefied gas l as described above occurs in the vaporization pipe 114, the periodic fluctuation of the interface b (that is, the gas g and the liquefied gas l Although the pressure fluctuation accompanying the volume change also occurs in the vaporization tube 114, a temporal shift (phase shift) occurs between the periodic fluctuation of the interface b and the pressure fluctuation in the vaporization pipe 114 (FIG. 16). reference). This phase shift may increase periodic fluctuations in the pressure in the tube. When the periodic fluctuation of the pressure in the pipe is increased in this way, the increased pressure fluctuation propagates to each pipe 104, 106, 110, 112, 114, 116, 118 constituting the vaporizer 100, The vibration which makes this pressure fluctuation the exciting force arises.

  The present invention has been made based on such a discovery, and a plurality of vaporization tubes for vaporizing a low-temperature liquefied gas extending in the vertical direction and flowing inside by heat exchange with the outside, and the plurality of vaporizations An inter-vaporization pipe distribution pipe connected to the lower ends of the pipes to distribute the low-temperature liquefied gas to the vaporization pipes, and a plurality of internal heat transfer pipes arranged inside the vaporization pipes and shorter than the vaporization pipes, Is provided. And the pipe between the vaporization pipes supplies the low-temperature liquefied gas to the outer space formed between the vaporization pipe and the inner heat transfer pipe and the inner space inside the inner heat transfer pipe, respectively. The inner heat transfer tube is configured to join a part of the low-temperature liquefied gas flowing in the inner space to the vaporized low-temperature liquefied gas before reaching the upper end of the inner heat transfer tube.

  According to the present invention, the temperature difference and density difference between the gas phase (vaporized) low-temperature liquefied gas and the liquid-phase low-temperature liquefied gas that merge in the region around the upper end (tip) of the inner heat transfer tube (confluence region) are suppressed. Thus, the periodic fluctuation of the interface between the gas phase low temperature liquefied gas and the liquid phase low temperature liquefied gas in the merged region is suppressed.

  Specifically, according to the inner heat transfer tube, before reaching the merge region near the upper end of the inner heat transfer tube, a part of the liquid low-temperature liquefied gas flowing in the inner space is vaporized by flowing in the outer space. Merges with (gas phase) low-temperature liquefied gas. For this reason, before the low-temperature liquefied gas in the gas phase reaches the joining region, the temperature decreases and the density increases. As a result, the temperature difference and the density difference between these low-temperature liquefied gases when the low-temperature liquefied gas in the gas phase and the low-temperature liquefied gas in the liquid phase merge in the merging region are suppressed. Periodic fluctuations at the interface between the liquefied gas and the low-temperature liquefied gas in the liquid phase are suppressed. As a result, it is possible to suppress the vibration of the vaporizer and the piping system connected to the vaporizer due to the periodic fluctuation of the interface.

  For example, specifically, the inner heat transfer tube has a through-hole in the tube wall, so that the low-temperature liquefied gas that has simultaneously passed through the respective positions in the transverse section in the lower part of the inner space reaches the upper end of the inner heat transfer tube. Before, a part of the gas can be merged with the gas phase low-temperature liquefied gas flowing in the outer space through the through hole in the tube wall. This suppresses the temperature difference and density difference between the gas phase low temperature liquefied gas that has passed through the outer space and the liquid phase low temperature liquefied gas that has passed through the inner space when merging in the merging region. Fluctuations are prevented or suppressed.

  In this case, it is preferable that the through hole is provided at least in the upper part of the inner heat transfer tube. By providing the through hole at a position close to the merging region in this manner, the gas phase low-temperature liquefied gas whose temperature has been reduced due to the merge of part of the liquid-phase low-temperature liquefied gas is exchanged by the heat exchange with the outside. It is possible to reliably reach the confluence area before rising to the previous temperature. Thereby, a temperature difference and a density difference between the low-temperature liquefied gas in the gas phase and the low-temperature liquefied gas in the liquid phase in the merge region can be suitably suppressed.

  Furthermore, it is more preferable that the plurality of through holes are provided in the inner heat transfer tube, and the plurality of through holes are arranged from the upper part to the lower side of the inner heat transfer tube.

  According to such a configuration, a sufficient amount of the liquid-phase low-temperature liquefied gas merges with the gas-phase low-temperature liquefied gas through each through-hole until the gas-phase low-temperature liquefied gas flows through the outer space and reaches the merge region. be able to. As a result, the temperature difference and the density difference between the gas-phase low-temperature liquefied gas and the liquid-phase low-temperature liquefied gas in the merge region can be sufficiently reduced. Periodic fluctuations in the interface with the low-temperature liquefied gas in the phase can be suppressed more effectively.

  In this case, it is preferable that the plurality of through holes arranged in the vertical direction are provided in a region from the upper end of the internal heat transfer tube to 20 to 40% of the length of the internal heat transfer tube in the vertical direction. Thereby, the temperature difference and density difference of the low temperature liquefied gas of a gaseous phase and the low temperature liquefied gas of a liquid phase in a confluence | merging area | region can be suppressed suitably.

  Further, the inner heat transfer tube has a plurality of through holes in the tube wall at the same height position, and the plurality of through holes at the same height position are equally spaced along the circumferential direction of the inner heat transfer tube. It is preferable to arrange | position.

  According to such a configuration, the bias of the temperature distribution of the low-temperature liquefied gas in the circumferential direction of the vaporization tube (inner heat transfer tube) is suppressed, and the decrease in vaporization efficiency due to the bias of the temperature distribution in the circumferential direction is suppressed in the vaporizer. be able to.

  Further, the inner heat transfer tube may have a notch extending in the vertical direction from the upper end surface of the inner heat transfer tube to the lower side in the tube wall of the inner heat transfer tube.

  Even in such a configuration, the low-temperature liquefied gas that has simultaneously passed through the respective positions in the cross section in the lower part of the inner space reaches the upper end of the inner heat transfer tube, and a part of the gas flows through the outer space through the tube wall notch. The phase can be merged into a low temperature liquefied gas. This suppresses the temperature difference and density difference between the gas phase low temperature liquefied gas that has passed through the outer space and the liquid phase low temperature liquefied gas that has passed through the inner space when merging in the merging region. Fluctuations are prevented or suppressed.

  In addition, since the notch has a predetermined length, a sufficient amount of the low-temperature liquefied gas in the liquid phase until the low-temperature liquefied gas in the gas phase flows through the outer space and reaches the merged region is formed in the gas phase through the notch. It becomes possible to join the low-temperature liquefied gas. As a result, the temperature difference and density difference between the gas-phase low-temperature liquefied gas and the liquid-phase low-temperature liquefied gas in the merging region can be sufficiently reduced.

  Furthermore, since the notch extends downward from the upper end surface of the inner heat transfer tube, the gas phase low temperature liquefied gas whose temperature has been lowered due to the merge of part of the liquid phase low temperature liquefied gas becomes the heat from the outside. The exchange can reliably reach the joining area before the temperature rises to the temperature before joining.

  In this case, it is preferable that a plurality of the notches are provided in the tube wall, and the plurality of notches are arranged at equal intervals along the circumferential direction of the inner heat transfer tube.

  According to such a configuration, the bias of the temperature distribution of the low-temperature liquefied gas in the circumferential direction of the vaporization tube (inner heat transfer tube) is suppressed, and the decrease in vaporization efficiency due to the bias of the temperature distribution in the circumferential direction is suppressed in the vaporizer. be able to.

  Moreover, it is preferable that the said notch is provided in the area | region from 20 to 40% of the length of the said internal heat exchanger tube in the up-down direction from the upper end of the said internal heat exchanger tube. Thereby, the temperature difference and density difference of the low temperature liquefied gas of a gaseous phase and the low temperature liquefied gas of a liquid phase in a confluence | merging area | region can be suppressed suitably.

  As described above, according to the present invention, when a low-temperature liquefied gas is vaporized in an internal heat transfer tube provided in the vaporization tube, vibration is generated in the vaporization device or / and a piping system connected to the vaporization device. It is possible to provide a low-temperature liquefied gas vaporizer that is unlikely to occur.

It is a schematic structure perspective view of the vaporizer of the low-temperature liquefied gas concerning this embodiment. It is a schematic diagram (front view) which shows the state of piping of the said vaporization apparatus. It is a schematic diagram (side view) which shows the state of piping of the said vaporization apparatus. It is an expanded cross-sectional view of the lower part of the vaporization pipe | tube in the said vaporization apparatus. (A) is a figure for demonstrating the internal heat exchanger tube arrange | positioned in the said vaporization pipe | tube, (B) is a figure for demonstrating the internal heat exchanger tube which concerns on other embodiment. It is a schematic diagram for demonstrating the pipe | tube in a header in which the some hole was each provided in the position corresponding to each vaporization pipe | tube. It is an expanded sectional view for demonstrating the pipe | tube in a header in which the some hole was each provided in the position corresponding to each vaporization pipe | tube. (A) is a side view for demonstrating the seawater supply part of the said vaporization apparatus, (B) is a front view for demonstrating the seawater supply part of the said vaporization apparatus. (A) is a figure which shows the change of the temperature of NG and LNG in the vaporization pipe | tube of the vaporization apparatus provided with the internal heat transfer pipe | tube without a through-hole, (B) shows the change of the density of NG and LNG in the said vaporization pipe | tube. FIG. (A) is a figure which shows the change of the temperature of NG and LNG in the vaporization pipe | tube of the vaporization apparatus which concerns on this embodiment, (B) is a figure which shows the change of the density of NG and LNG in the said vaporization pipe | tube. It is a figure for demonstrating the structure of the internal heat exchanger tube which concerns on other embodiment. It is a figure for demonstrating the structure of the internal heat exchanger tube which concerns on other embodiment. It is a schematic perspective view of a conventional low temperature liquefied gas vaporizer. (A) is a longitudinal cross-sectional view for demonstrating the vaporization pipe | tube and internal heat exchanger tube in the conventional low temperature liquefied gas vaporizer, (B) in the XI-XI position of FIG. 11 in the said vaporization pipe | tube and an internal heat exchanger tube It is sectional drawing. It is a figure for demonstrating the principle of the periodic fluctuation | variation of the interface in the junction part (merging area | region) of NG and LNG. It is a figure which shows the displacement of the said interface which arises in a vaporization pipe | tube, and the displacement of a pressure.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  The low-temperature liquefied gas vaporizer according to the present embodiment (hereinafter, also simply referred to as “vaporizer”) exchanges the supplied low-temperature liquefied gas with an external heat exchange liquid, thereby This is a so-called open rack type vaporizer (ORV) for vaporization. In the vaporizer of this embodiment, liquefied natural gas (LNG) is vaporized. In this embodiment, seawater is used as the heat exchange liquid.

  Specifically, as shown in FIGS. 1 to 5 (B), FIG. 8 (A), and FIG. 8 (B), the vaporizer includes a plurality of (two in this embodiment) vaporizer block blocks 11; The distribution pipe 12 that distributes LNG to each vaporization pipe block 11, the collection pipe 14 that collects natural gas (NG) that is LNG vaporized in each vaporization pipe block 11, and the surface of each vaporization pipe panel 16 flow down. Thus, the seawater supply part (liquid supply part) 30 which supplies seawater to the upper part of the vaporization pipe panel 16 is provided. In addition, the number of the vaporization pipe blocks 11 provided in the vaporizer 10 is not limited to plural, and may be one.

  Each vaporizing pipe block 11 includes a plurality of (in this embodiment, five) vaporizing pipe panels 16, a supply side manifold 17 that distributes LNG from the distribution pipe 12 to each vaporizing pipe panel 16, and each vaporizing pipe panel 16. And a delivery-side manifold 19 that collects vaporized LNG (that is, NG) and sends it to the collecting pipe 14. The number of vaporization tube panels 16 included in one vaporization tube block 11 is not limited to five, and may be another number.

  Each vaporization tube panel 16 has a plurality (90 in this embodiment) of vaporization tubes (heat transfer tubes) 21 arranged in parallel with each other on a vertical plane, and a plurality of vaporization tubes 21 arranged inside each vaporization tube 21. , The supply side header 22 that distributes the LNG from the supply side manifold 17 to each vaporization pipe 21, and the transmission side header that collects the LNG vaporized in each vaporization pipe 21 and sends it to the transmission side manifold 19. 24. The number of vaporization tubes included in one vaporization tube panel 16 is not limited to 90, and may be other numbers.

  Each vaporization tube 21 is a tube formed of a metal material having a high thermal conductivity such as aluminum or an aluminum alloy and extending in the vertical direction. The vaporization tube 21 of the present embodiment has an inner peripheral surface 21a in which radial irregularities are repeated in the circumferential direction in order to increase the contact area with the LNG flowing inside (see FIG. 4). Further, the vaporizing pipe 21 has a plurality of fins formed on the outer peripheral surface 21b in order to increase the contact area with the seawater flowing down along the vaporizing pipe 21.

  In addition, the specific structure of the inner peripheral surface and outer peripheral surface of the vaporization pipe | tube 21 is not limited to said structure, A cross section may be circular or substantially circular.

  The inner heat transfer tube 25 is a member for suppressing icing on the outer surface of the lower portion of the vaporization tube 21 and ensuring sufficient heat transfer performance to efficiently vaporize LNG, and is disposed inside each vaporization tube 21. The tube is shorter than the vaporizing tube 21. The internal heat transfer tube 25 is formed of a metal material having a high thermal conductivity such as aluminum or an aluminum alloy, like the vaporization tube 21. The inner heat transfer tube 25 defines an outer space S <b> 1 between the inner heat transfer tube 25 and the inner space S <b> 2. Specifically, the inner heat transfer tube 25 of the present embodiment has a cylindrical outer peripheral surface 25b, a cylindrical inner peripheral surface 25a positioned inside the outer peripheral surface 25b, and a tube axis (vertical direction). And a vertical upper end surface 25c. The upper end surface need not be limited to a surface perpendicular to the tube axis, and may be inclined with respect to the tube axis (see, for example, FIG. 12B).

  The inner heat transfer tube 25 is disposed inside the vaporization tube 21 so as to be coaxial with the vaporization tube 21. When the inner heat transfer tube 25 is disposed inside the vaporizing tube 21, the outer peripheral surface 25 b comes into contact with each tip of the portion projecting inwardly on the inner peripheral surface 21 a of the vaporizing tube 21. Has an outer diameter. Due to the inner peripheral surface 21a of the vaporizing tube 21 and the outer peripheral surface 25b of the inner heat transfer tube 25, an outer space S1 continuous in the axial direction and intermittent in the circumferential direction is formed between the inner heat transfer tube 25 and the vaporization tube 21. It is formed. The shape of the outer peripheral surface 25b of the inner heat transfer tube 25 and the inner peripheral surface 21a of the vaporization tube 21 is not limited to the shape that forms the intermittent outer space S1 in the circumferential direction as in the present embodiment. The shape may form a continuous outer space in the direction. That is, both the inner peripheral surface of the vaporization tube and the outer peripheral surface of the inner heat transfer tube may be cylindrical.

  The inner heat transfer tube 25 is configured such that a part of the LNG that has simultaneously passed through each position in one transverse section i (see FIG. 5A) in the lower part of the inner space S2 is the upper end of the inner heat transfer tube 25 (in this embodiment, , Before reaching the upper end face 25c), the NG flowing in the outer space S1 is joined. In addition, the specific position of the cross section i is not limited to the position of this embodiment. That is, if the cross section i is perpendicular to the tube axis, it is between the upper end surface 25c and the lower end of the internal heat transfer tube 25, and the through hole 26 and notches 26A and 26B described later (FIG. 11A and FIG. 11 (B)) may be a cross section at any position below the lower side.

  Specifically, the internal heat transfer tube 25 of the present embodiment has a plurality of through holes 26 on the tube wall.

  Specifically, a plurality of (three in the example shown in FIG. 5A) through-holes 26 arranged from the upper part of the inner heat transfer tube 25 toward the supply-side header 22 are set as one set, and this set is the circumference of the inner heat transfer tube 25. It is arranged at equal intervals in the direction. In the example shown in FIG. 5A, four sets of the through holes 51 are arranged in the circumferential direction. It is preferable that the group of the through holes 26 is provided in a region of 20 to 40% of the length of the internal heat transfer tube 25 from the tip (upper end) of the internal heat transfer tube 25 toward the supply-side header 22. By being provided in such a region, it is possible to suitably suppress a temperature difference and a density difference between the gas phase LNG (that is, NG) and the liquid phase LNG that merge at the upper end of the internal heat transfer tube 25. Here, the upper end is the position of the upper end surface when the upper end surface 25c is perpendicular to the tube axis, and is the highest of the upper end surface when the upper end surface is inclined with respect to the tube axis. Position.

  The through holes 26 in each set may be arranged in a straight line in the vertical direction as in the present embodiment (see FIG. 5A), and at a predetermined angle with respect to the vertical direction. (See FIG. 5B). Further, since the outer space S <b> 1 of the present embodiment is intermittent in the circumferential direction, each through hole 26 is provided at a position corresponding to the outer space S <b> 1 in the circumferential direction of the inner heat transfer tube 25. Further, the diameter of each set of through holes 51 may not be constant. For example, the diameter of the hole 51 located on the upper side may be larger or smaller.

  The supply-side header 22 is a tube that extends in the horizontal direction along the vertical plane in which the vaporization tubes 21 are arranged. The supply-side header 22 is connected to each vaporization tube 21 included in one vaporization tube panel 16. The supply header 22 supplies LNG to the outer space S1 and the inner space S2. In addition, one end of the supply side header 22 is connected to the supply side manifold 17 so that LNG is supplied from the supply side manifold 17 via the header inner pipe 50 disposed therein.

  The header inner pipe 50 is a tubular member extending along the supply side header 22 and is disposed inside the supply side header 22 so as to be coaxial with the supply side header 22 (see FIG. 3). The header inner pipe 50 has an outer diameter smaller than the inner diameter of the supply-side header 22, so that when arranged inside the supply-side header 22, the outer circumferential surface of the header inner pipe 50 and the supply-side header 22 A predetermined space is formed between the inner peripheral surface. The header inner pipe 50 is connected to the supply-side manifold 17 so that LNG is supplied into the header inner pipe 50, and at a position corresponding to each vaporization pipe 21 on the pipe wall (peripheral wall) in the axial direction of the header inner pipe 50. Each has a hole 51. A plurality of (two holes in the present embodiment) are provided at positions corresponding to the respective vaporizing tubes 21 in the axial direction. Specifically, the plurality of holes 51 are arranged in the circumferential direction of the header inner pipe 50 at positions corresponding to the respective vaporization pipes 21 in the axial direction (positions below the vaporization pipes 21 in the present embodiment). It is out. In the present embodiment, the two holes 51 are provided at positions facing the horizontal direction. When three or more holes (four in the examples of FIGS. 6 and 7) are provided at positions corresponding to the respective vaporizing tubes 21, the holes 51 are disposed at positions corresponding to the respective vaporizing tubes 21. Are preferably arranged so as to be aligned in the circumferential direction of the header inner tube 50 so that the center thereof is located in the lower half of the header inner tube 50.

  In this way, the header inner pipe 50 is provided inside the supply side header 22 to form a double pipe structure, and a plurality of holes 51 are provided at positions corresponding to the vaporization pipes 21 of the header inner pipe 50 to thereby provide each vaporization. The flow rate of LNG distributed to the pipe 21 is equalized.

  Also, a plurality of holes 51 are provided at positions corresponding to the vaporization tubes 21 of the header inner pipe 50, and the plurality of holes 51 are arranged in the lower half of the header inner pipe 50 (specifically, the center of each hole 51 is (Arranged so as to be located in the lower half), the flow of LNG flowing into each vaporizing tube 21 becomes uniform. That is, LNG that has flowed out from the plurality of holes 51 at positions corresponding to the respective vaporization tubes 21 passes between the supply side header 22 and the header inner tube 50 toward the vaporization tube 21 and toward the upper side in the circumferential direction of the supply side header 22. By flowing into the vaporization tube 21 after flowing, LNG flows into the vaporization tube 21 immediately after flowing out of a hole provided in the upper portion of the header inner tube (for example, a position facing the lower end of the vaporization tube 21). Compared with the case, the flow of LNG becomes uniform.

  The delivery side header 24 is a pipe extending in parallel with the supply side header 22. The delivery side header 24 is connected to the upper end portion of each vaporization tube 21 included in one vaporization tube panel 16 and the delivery side manifold 19.

  The plurality of vaporizing tube panels 16 configured as described above are arranged in a direction (left-right direction in FIG. 2) orthogonal to the panel surface (the vertical surface on which the vaporizing tubes 21 are arranged) in a mutually parallel posture.

  The supply-side manifold 17 is a pipe extending in a direction intersecting with the supply-side header 22 (in the present embodiment, a direction substantially orthogonal to the sheet: a direction orthogonal to the paper surface in FIG. 3), and is included in one vaporization tube block 11. Connected to the supply side header 22 and the distribution pipe 12.

  The delivery-side manifold 19 is a pipe extending in a direction intersecting with the delivery-side header 24 (in the present embodiment, a direction substantially orthogonal to the paper: a direction orthogonal to the paper surface in FIG. 3), and is included in one vaporization tube block 11. Connected to the sending side header 24 and the collecting pipe 14.

  The distribution pipe 12 is a pipe extending substantially parallel to the supply side manifold 17 and is connected to each supply side manifold 17. Further, the distribution pipe 12 is provided with a supply side connection portion 12a for connecting a pipe P1 for supplying LNG to the vaporizer 10 from the outside.

  The collecting pipe 14 is a pipe extending substantially in parallel with the delivery side manifold 19 and is connected to each delivery side manifold 19. Further, the collecting pipe 14 is provided with a sending side connection portion 14a for connecting a pipe P2 for sending NG to the outside such as a consumption area.

  The seawater supply unit 30 includes a trough 31 disposed in the vicinity of the upper end of each vaporization tube panel 16, a seawater header 32 that supplies seawater to each trough 31, a seawater manifold 33 that distributes seawater to each seawater header 32, (See FIGS. 8A and 8B). The trough 31 supplies seawater to the upper end portion of each vaporization tube panel 16 so that the seawater flows down along the surface of the vaporization tube panel 16 (specifically, each vaporization tube 21 constituting the vaporization tube panel 16). The seawater supplied from the trough 31 and flowing down the surface of the vaporization tube panel 16 and the LNG flowing in the vaporization tubes 21 exchange heat through the tube walls of the vaporization tubes 21, whereby LNG is vaporized and NG. It becomes.

  The vaporizer 10 configured as described above vaporizes LNG as follows.

  Seawater is supplied from the trough 31 to the surface of each vaporization tube panel 16, and LNG is supplied to the distribution pipe 12 from a supply pump or the like through the pipe P1 connected to the supply side connection portion 12a. The distribution pipe 12 distributes LNG supplied by a supply pump or the like to each supply side manifold 17 connected to the distribution pipe 12, and each supply side manifold 17 supplies the LNG from the distribution pipe 12 to the supply side manifold 17. Are distributed to each supply-side header 22 connected to the. Each supply-side header 22 distributes the supplied LNG to each vaporization tube 21 connected to the supply-side header 22. Specifically, the supply-side header 22 supplies LNG to the outer space S1 and the inner space S2 formed inside each vaporizing tube 21.

  In each vaporization tube 21, the LNG supplied from the supply-side header 22 flows through the vaporization tube 21 from the lower end to the upper end. At this time, the LNG supplied to the outer space S1 becomes vaporized by the heat from the outside of the vaporization pipe 21 (specifically, the heat of seawater flowing down along the vaporization pipe 21). LNG supplied to the inner space S2 flows upward while remaining in a liquid phase. Specifically, in the lower part of the vaporization tube 21 (region where the inner heat transfer tube 25 is located), the LNG flowing in the outer space S1 has a smaller flow rate than the LNG flowing in the inner space S2, and heat exchange with the outside of the vaporization tube 21 is performed. Since it is easily performed, it is vaporized immediately, and this vaporized LNG (that is, NG) flows through the outer space S1. Therefore, the surface temperature of the vaporizing tube 21 is higher than that of the vaporizing tube in which the internal heat transfer tube 25 is not provided (the vaporizing tube in a state where the LNG before vaporization is flowing inside), and thereby the surface icing is not caused. It can be suppressed. Further, when LNG is vaporized in the outer space S1, forced convection boiling caused by a temperature difference between the inner peripheral surface 21a of the vaporizing tube 21 and the outer peripheral surface 25b of the inner heat transfer tube 25 is strengthened, and the heat transfer coefficient in the region is high. It has become.

  Before the gas phase LNG flowing in the outer space S1, that is, NG, and the liquid phase LNG flowing in the inner space S2 merge around the upper end (tip) of the inner heat transfer tube 25, a part of the LNG is a through hole. 26. Specifically, when LNG that has passed through each position in the cross section i below the inner space S2 reaches the position of the through hole 26 provided in the upper part of the inner heat transfer tube 25, a part of the LNG passes through the through hole 26 to the outside. It flows into the space S1 and merges with NG flowing through the outer space S1. That is, at the intermediate position of the inner heat transfer tube 25 (between the lower end and the upper end), a part of the LNG flowing through the inner space S2 joins the NG flowing through the outer space S1, thereby lowering the temperature of the NG and increasing the density. Thereby, when the NG flowing through the outer space S1 and the LNG flowing through the inner space S2 are merged around the upper end of the inner heat transfer tube 25 (merging region), compared to the case where no through hole is provided in the inner heat transfer tube. The temperature difference and density difference between NG and LNG are suppressed.

  Thereafter, the merged NG and LNG are completely vaporized by continuing the heat exchange with the seawater flowing along the vaporizing pipe 21 through the tube wall of the vaporizing pipe 21 while flowing upstream through the vaporizing pipe 21. The

  LNG vaporized in each vaporization tube 21, that is, NG is collected by the delivery side header 24 and delivered to the delivery side manifold 19. The NG sent to the delivery side manifold 19 is sent to the consumption area or the like through the collecting pipe 14 and the pipe P2 connected to the delivery side connection portion 14a.

  According to the vaporizer 10 described above, a temperature difference and a density difference between NG (gas phase LNG) and LNG (liquid phase LNG) joining in the region around the upper end of the inner heat transfer tube 25 (merging region) can be suppressed. Thereby, the periodic fluctuation | variation of the interface of NG and LNG in a confluence | merging area | region is suppressed.

  Specifically, according to the inner heat transfer tube 25 of the present embodiment, before reaching the merge region near the upper end of the inner heat transfer tube 25, a part of the LNG flowing in the inner space S2 merges with NG flowing in the outer space S1. To do. For this reason, before the said NG reaches | attains a joining area | region, the temperature falls and a density rises. As a result, the temperature difference and density difference between NG and LNG when NG and LNG merge in the merge region are suppressed, thereby suppressing periodic fluctuation of the interface between NG and LNG in the merge region. Is done. As a result, it is possible to suppress vibrations of the vaporizer 10 and the piping system connected to the vaporizer 10 due to the periodic fluctuation of the interface.

  In the present embodiment, since the through hole 26 is provided in the upper part of the internal heat transfer tube 25, that is, a position close to the merge region, NG, in which a part of the LNG is merged and the temperature is reduced, is exchanged with the outside. Thus, it is possible to reliably reach the merge area before the temperature rises to the temperature before the merge. Thereby, the temperature difference and density difference of NG and LNG in a confluence | merging area | region can be suppressed suitably.

  Further, in the tube wall of the inner heat transfer tube 25, a plurality of through holes 26, 26,... Are arranged in the vertical direction, so that a sufficient amount of LNG is obtained until the NG flows through the outer space S1 and reaches the merge region. It can merge with NG through each through hole 26. Thereby, the temperature difference and density difference between NG and LNG in the merging region can be sufficiently reduced, and as a result, the periodic fluctuation of the interface between NG and LNG in the merging region can be more effectively suppressed. Can do.

  Moreover, in this embodiment, since the several through-holes 26, 26, ... of the same height position of the internal heat exchanger tube 25 are arrange | positioned at equal intervals along the circumferential direction of the internal heat exchanger tube 25, the vaporization pipe | tube 21 ( The deviation of the temperature distribution of the LNG in the circumferential direction of the inner heat transfer tube 25) can be suppressed, and a decrease in vaporization efficiency caused by the deviation of the temperature distribution in the circumferential direction in the vaporizer 10 can be suppressed.

  In order to confirm the effect of the through hole provided in the internal heat transfer tube, the configuration of the vaporization device 10 of the above embodiment is the same as that of the vaporization device 10 of the above embodiment except for the vaporization device 10 of the above embodiment and the internal heat transfer tube not provided with the through hole. Using a vaporizer, the temperature difference and density difference between NG and LNG when NG flowing in the outer space and LNG flowing in the inner space merged were examined.

  Specifically, in each of the vaporizers, the length of the vaporizer tube was 6 m, the length of the internal heat transfer tube was 2.5 m, and LNG at about −165 ° C. was supplied to these vaporizers at a pressure of 64 bar. The results are shown in FIGS. 9 (A) to 10 (B). FIG. 9A and FIG. 9B show the temperature change and density change of NG and LNG in the vaporization tube in the vaporization apparatus provided with the internal heat transfer tube having no through hole. FIG. 10A and FIG. 10B show the temperature change and density change of NG and LNG in the vaporization tube 21 of the vaporization apparatus 10 of the above embodiment.

  From FIG. 9A and FIG. 9B, in the vaporization apparatus having the inner heat transfer tube without the through hole, a merged region of the NG flowing through the outer space and the LNG flowing through the inner space (the lower end of the vaporization tube) It can be seen that the temperature difference at 10 m to 2.5 m is 10 ° C. or more and the density difference is 30% or more. On the other hand, from FIG. 10 (A) and FIG. 10 (B), in said vaporization apparatus 10, the confluence | merging area | region (position of 2.5 m) of NG which flowed through outer space, and LNG which flowed through inner space. It can be seen that the temperature difference is suppressed to 3 ° C. and the density difference is suppressed to several percent.

  From the above, it was confirmed that the temperature difference and the density difference between NG and LNG in the merging region can be effectively suppressed by providing a through hole in the inner heat transfer tube.

  In addition, the low temperature liquefied gas vaporization apparatus of this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the summary of this invention, a various change can be added.

  The specific configuration of the internal heat transfer tube 25 is not limited. For example, in the inner heat transfer tube 25 of the above embodiment, by providing a plurality of through holes 26 in the tube wall, LNG that has simultaneously passed through each position in the transverse section of the inner space S2 reaches the upper end of the inner heat transfer tube 25. A part thereof is previously joined to the NG flowing in the outer space S1, but the present invention is not limited to this. As shown in FIGS. 11 (A) and 11 (B), the inner heat transfer tubes 25A, 25B are notched 26A extending downward from the upper end surface 25c of the inner heat transfer tubes 25A, 25B along the vertical direction. 26B may be provided on the tube wall. The notches 26A and 26B may extend straight in the vertical direction or may be inclined with respect to the vertical direction.

  Further, the specific shape of the notch is not limited. For example, a rectangular cutout 26A having a constant width at each position in the vertical direction as shown in FIG. 11A may be used, or a cutout having a shape with a non-constant width in the vertical direction (shown in FIG. 11B). In an example, a notch 26B) having a shape that becomes wider toward the upper side may be used.

  In order to suppress the deviation of the temperature distribution of the LNG in the circumferential direction of the vaporization tube 21 and to suppress the decrease in vaporization efficiency caused by the deviation of the temperature distribution in the circumferential direction, these notches 26A and 26B are provided with the inner heat transfer tube 25A. , 25B is preferably provided so as to be equally spaced in the circumferential direction, but may not be equally spaced.

  Similarly to the notches, a plurality of through holes may be arranged on the tube wall of the internal heat transfer tube so that the intervals between the through holes in the circumferential direction are different from each other.

  Moreover, the structure provided with only one through-hole or notch may be sufficient in the circumferential direction of the internal heat transfer tube.

  As shown in FIG. 11C, the internal heat transfer tube 25C may have both the through hole 26 and the notch 26B in the tube wall.

  As shown in FIG. 12A, a plurality of notches 26C may be provided continuously in the circumferential direction. Also in this case, each notch 26C extends downward from the distal end surface (surface indicated by a dotted line in FIG. 12A) 25c of the internal heat transfer tube 25D.

  Further, as shown in FIG. 12B, the inner heat transfer tube 25E is formed such that the upper end surface of the tube wall continuously decreases from one end to the other end in the diameter of the inner heat transfer tube 25E. May be. Also in this case, a part of the LNG that has simultaneously passed through each position in the cross section below the inner space S2 reaches the upper end of the inner heat transfer tube 25E (the upper end of the tube wall on the one end side of the diameter). The NG flowing through S1 can be merged. Thereby, the temperature difference and density difference of NG and LNG which join in the joining area | region around the said upper end of the internal heat exchanger tube 25E are suppressed.

  Moreover, as shown in FIG. 12C, a large number of through holes 26D may be provided in the upper part of the internal heat transfer tube 25E. Even with this configuration, a part of the LNG that has simultaneously passed through the respective positions in the cross section of the inner space S2 reaches the upper end of the inner heat transfer tube 25E, and a part of the LNG is merged with the vaporized LNG by flowing through the outer space S1. be able to.

DESCRIPTION OF SYMBOLS 10 Vaporizer 11 Evaporation pipe block 12 Distribution pipe 14 Collecting pipe 16 Evaporation pipe panel 17 Supply side manifold 19 Outlet side manifold 21 Evaporation pipe 22 Supply side header (evaporation pipe distribution pipe)
24 Sending side header 25 Inner heat transfer tube 26 Through hole 30 Seawater supply part b Boundary part g Low-temperature liquefied gas in gas phase l Low-temperature liquefied gas in liquid phase S1 Outer space S2 Inner space

Claims (6)

A plurality of vaporization tubes for vaporizing a low-temperature liquefied gas extending vertically and flowing inside by heat exchange with the outside;
An inter-vaporization pipe distribution pipe connected to the lower ends of the plurality of vaporization pipes and distributing the low-temperature liquefied gas to the vaporization pipes, respectively.
A sending-side header connected to each upper end of each of the plurality of vaporization tubes so as to collect the low-temperature liquefied gas vaporized in the process of flowing upward in each vaporization tube;
A plurality of internal heat transfer tubes that are disposed inside each vaporization tube and have an opening that opens downward and shorter than the vaporization tube, and
The inner heat transfer tube is disposed in the vaporization tube in a posture that forms an outer space between the vaporization tube and the inner heat transfer tube, and the internal heat transfer tube passes through the opening from the inter-vaporization tube distribution pipe. Before the part of the low-temperature liquefied gas flowing into the inner space in the tube reaches the upper end of the inner heat transfer tube, the outer space passes through the gap between the vaporization tube and the lower end portion of the inner heat transfer tube from the inter-vaporization pipe. Is combined with the low-temperature liquefied gas that has flowed into the
The inner heat transfer tube is vaporized in a merging region where the low-temperature liquefied gas that has been vaporized by rising the outer space and the low-temperature liquefied gas that has flowed upward from the upper end of the inner heat-transfer tube and merged. Before the low-temperature liquefied gas arrives, the pipe wall is made to lower the temperature of the vaporized low-temperature liquefied gas by joining a part of the low-temperature liquefied gas flowing into the inner space to the vaporized low-temperature liquefied gas. A vaporizer for low-temperature liquefied gas having a through-hole provided in at least the upper part of the tube or a notch extending downward from the upper end surface of the tube wall along the vertical direction.   The low-temperature liquefied gas vaporization device according to claim 1, wherein the inner heat transfer tube is provided with a plurality of the through holes, and the plurality of through holes are arranged from the upper part to the lower side of the inner heat transfer tube.   3. The low-temperature liquefied gas according to claim 2, wherein the plurality of through holes arranged along the vertical direction are provided in a region from the upper end of the inner heat transfer tube to 20 to 40% of the length of the inner heat transfer tube in the vertical direction. Vaporizer.   The inner heat transfer tube has a plurality of through holes in the tube wall at the same height position, and the plurality of through holes at the same height position are arranged at equal intervals along the circumferential direction of the inner heat transfer tube. The vaporizer for low-temperature liquefied gas according to claim 2 or 3.   5. The low temperature according to claim 1, wherein a plurality of the notches are provided in the tube wall, and the plurality of notches are arranged at equal intervals along a circumferential direction of the inner heat transfer tube. Liquefied gas vaporizer.   6. The low-temperature liquefied gas according to claim 1, wherein the notch is provided in a region from the upper end of the inner heat transfer tube to 20 to 40% of the length of the inner heat transfer tube in the vertical direction. Vaporizer.

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