JP2009030765A - Liquefied natural gas vaporizing device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the need for sprinkling water to defrost an LNG vaporizing device or greatly reduce its frequency. <P>SOLUTION: The LNG vaporizing device comprises a vaporizing pipe 10 for vaporizing LNG, and a defrosting device 40. The vaporizing pipe 10 has a plurality of main pipes 12 arrayed in the horizontal direction, and connection pipes 14 for connecting the upper or lower ends of mutually adjacent main pipes, to each other. Thus, a meandering flow path is formed including a vaporizing part 10a. At least a lowest temperature pipe 12L out of the main pipes 12 is filled with a turbulent flow promoting material. The defrosting device 40 blows defrosting gas to the specified main pipes including the lowest temperature pipe 12L to remove frost deposited on the surfaces of the main pipes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for vaporizing liquefied natural gas by exchanging heat with outside air.

  Conventionally, what is described in Patent Document 1 is known as an apparatus for vaporizing liquefied natural gas by exchanging heat with outside air.

  This apparatus has an evaporation section for heating and evaporating the liquefied natural gas, and a heating section for further heating the natural gas generated by the evaporation. The evaporation unit includes a lower header and an upper header that are piped in a horizontal direction, and a plurality of heat transfer tubes. The upper header is disposed above the lower header, and the heat transfer tube is piped between the lower header and the upper header. These heat transfer tubes are arranged along the longitudinal direction of the two headers, and upper and lower ends thereof are connected to the upper header and the lower header, respectively. The warming part is constituted by a bent pipe meandering up and down, and the bent pipe is connected to the upper header.

In this apparatus, liquefied natural gas is introduced into the lower header. The liquefied natural gas is distributed from the lower header to the heat transfer tubes, and while rising in these heat transfer tubes, heat is exchanged with the outside air to raise the temperature, and the vapor reaches the boiling point and vaporizes. By this vaporization, natural gas is generated in each heat transfer tube, and these natural gases merge into the upper header. The natural gas is further heated in a bent pipe constituting the heating unit, and finally distributed to each demand area.
JP 2005-156141 A

  In the vaporizer, the temperature drop at the lower surface of each heat transfer tube is significant, and this temperature drop causes frost formation and growth on the surface. Thus, the frost adhering to the surface of the heat transfer tube prevents good heat exchange between the liquefied natural gas in the heat transfer tube and the outside air, and must be periodically removed. For this defrosting, it is necessary to temporarily stop the operation of the apparatus and spray the frost. This watering work increases costs due to an increase in water bills and electricity bills, and significantly reduces the operating efficiency of the device.

  In view of such circumstances, the present invention eliminates the need for watering work for defrosting or significantly reduces the frequency of the liquefied natural gas, which can realize an efficient vaporization operation at low cost. The purpose is to provide a vaporizer.

  The present inventors paid attention to the relationship between the surface temperature of the heat transfer tube and the quality of frost adhering to the surface as means for solving the above problems. Specifically, when the surface of the heat transfer tube is sufficiently low in temperature (for example, −120 ° C. or less), so-called powder-like high-quality frost adheres to the surface, and this frost is easily formed by spraying air or the like. It is possible to remove. On the other hand, if the surface temperature of the heat transfer tube is relatively high (for example, about 0 ° C.), frost close to ice adheres to the surface, and this frost must be heated by hot water or high-temperature steam. It cannot be removed.

  In order to attach the good quality (that is, easy to remove) frost like the former to the heat transfer tube, it is effective to secure the low temperature region as described above long in the vertical direction in the heat transfer tube. However, the conventional vaporizer as described above is designed so that the liquefied natural gas reaches its boiling point and vaporizes in a plurality of heat transfer tubes arranged in parallel with each other. The gradient of the surface temperature of the heat tube is large, and thus the low temperature region as described above cannot be secured long up and down. That is, in the conventional vaporizer, since the region where the surface temperature of each heat transfer tube is sufficiently low is limited to a small portion below the heat transfer tube, it is possible to ensure a long region where good quality frost adheres. Therefore, it is difficult to perform defrosting effectively and easily.

  The present invention has been made from such a viewpoint, and is an apparatus for vaporizing liquefied natural gas, in which a flow path through which the liquefied natural gas flows is formed, and the liquefaction flowing through the flow path An evaporating section for heating and evaporating the liquefied natural gas by exchanging heat between natural gas and outside air, a vaporizing pipe including a heating section for further heating the evaporated natural gas, and a surface of the evaporating pipe And a defrosting device for removing frost adhering to the surface. The vaporizing pipe extends in the vertical direction and is connected to a plurality of main pipes arranged in a specific horizontal direction and upper ends or lower ends of the main pipes adjacent to each other alternately, thereby the evaporation section and the A connecting pipe that forms a meandering flow path including both of the heating parts, and the main pipe is provided inside the main pipe over the entire flow path direction of the coldest pipe that is the coldest main pipe among the main pipes. A turbulent flow promoting material that promotes turbulent flow of liquefied natural gas in the pipe. The defrosting device removes frost attached to the surface of the main pipe by blowing a defrosting gas onto the surface of a specific main pipe including at least the coldest pipe.

  Moreover, this invention is the vaporization method of the liquefied natural gas using the said apparatus. This method includes a step of supplying liquefied natural gas into a vaporization pipe and vaporizing the liquefied natural gas by heat exchange between the liquefied natural gas and outside air, and defrosting for removing frost adhering to the vaporization pipe by the vaporization. Process. In the step of vaporizing the liquefied natural gas, as the vaporization pipe, a plurality of main pipes extending in the vertical direction and arranged in a specific horizontal direction, and upper ends or lower ends of the main pipes adjacent to each other are alternately arranged. By connecting, a connection pipe that forms a meandering flow path including both the evaporation section and the heating section, and at least the flow path direction of the coldest pipe that is the coldest main pipe among the main pipes. What is provided in the inside of a main pipe and is provided with the turbulent flow promoting material which promotes the turbulent flow of the liquefied natural gas in the said main pipe is used. In the defrosting step, frost adhering to the surface is removed by blowing a defrosting gas on the surface of a specific main pipe including at least the coldest pipe among the main pipes.

  In the above apparatus and method, the combination of the meandering flow path for vaporizing the liquefied natural gas formed by the vaporizing pipe and the turbulent flow promoting material provided in at least the coldest pipe adheres good quality frost. It is possible to ensure a long area and to remove the frost by blowing a defrosting gas.

  Specifically, in the vaporization tube of the apparatus, the liquefied natural gas only needs to be evaporated and heated in a continuous meandering channel while meandering up and down, so that a plurality of transmission lines arranged in parallel as in the prior art. Unlike an apparatus in which liquefied natural gas must be vaporized in each heat pipe, it is possible to reduce the temperature gradient in the vertical direction in each main pipe forming the meandering flow path. Further, since a turbulence promoting material is provided at least inside the coldest pipe of the main pipe, for example, a flow rate at which the entire area of the coldest pipe becomes the evaporation portion (that is, a liquid phase in the coldest pipe). If the liquefied natural gas is supplied into the vaporization pipe at a flow rate that can be secured, the heat exchange between the coldest pipe and the liquefied natural gas is promoted, so that the coldest pipe has a low temperature ( For example, it is possible to maintain a temperature lower than the vaporization point of liquefied natural gas).

  The above makes it possible to ensure a long low-temperature region to which good-quality frost adheres in the vaporizing tube. Therefore, the operation of the vaporizer is stopped with a simple configuration in which the defroster sprays the defrosting gas in the normal temperature region (for example, 0 ° C. or higher and 40 ° C.) against the frost adhering to such a region. It is possible to perform defrosting. This defrosting maintains good heat exchange between the liquefied natural gas and the outside air in the low temperature region, and improves the operating efficiency of the apparatus.

  The defrosting device includes, for example, a gas blowing pipe into which the defrosting gas is introduced, and the gas blowing pipe injects the defrosting gas supplied to the outside to the outside. It is preferable that the defrosting gas injected from the gas injection port is disposed at a position where it hits the surface of the specific main pipe. In this defrosting device, it is possible to spray the defrosting gas on a proper position of the vaporizing tube by a simple operation of simply introducing the defrosting gas into the gas blowing tube.

  It is more preferable that the gas spray pipe is arranged over a plurality of stages arranged in the vertical direction. Arrangement of such a plurality of gas spray pipes makes it possible to spray the defrosting gas evenly in the vertical direction on a specific main pipe.

  Further, in the case of providing a plurality of the vaporization tubes, these vaporization tubes are arranged in a direction orthogonal to the arrangement direction of the main tubes, the gas blowing tube extends in the arrangement direction of the vaporization tubes, and It is preferable to have a plurality of gas injection ports for blowing the defrosting gas to a specific main pipe of each vaporization pipe. In this vaporizer, the processing efficiency is further enhanced by the combined use of a plurality of vaporizer tubes. In addition, it is possible to simultaneously spray the defrosting gas from the common gas blowing pipe to the plurality of vaporizing pipes. That is, in this vaporizer, a plurality of vaporizer tubes can be defrosted simultaneously with a simple structure.

  The injection direction of the defrosting gas from the gas spray pipe is not particularly limited. When the gas injection port of the gas spray tube is opened in the horizontal direction or downward from the horizontal direction, it is possible to prevent rain or the like from adversely affecting the defrosting gas injection from the gas injection port. The On the contrary, when the gas injection port is opened upward, turbulent flow is generated due to the mixture of the gas injected upward from the gas injection port and the cold air (atmosphere) descending between the vaporization tubes. Therefore, the defrosting effect is enhanced.

  As described above, the present invention secures a long low temperature region by using a vaporization pipe that forms a meandering flow path from the evaporation section to the heating section, thereby improving the quality of the frost attached to the vaporization pipe. Can be easily removed by blowing a defrosting gas. Therefore, the conventional watering work for defrosting becomes unnecessary, or the frequency can be reduced significantly.

  Preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of a vaporizer for liquefied natural gas (hereinafter referred to as “LNG”) according to this embodiment, FIG. 2 is a front view of the device as seen from the front side (low temperature side), and FIG. It is a top view of the apparatus. This apparatus includes a plurality of vaporization tubes 10, a support frame 20 that supports these vaporization tubes 10, and a liquefied natural gas supply means. As this liquefied natural gas supply means, a liquid supply pipe, a pump, and the like are suitable, but in this embodiment, a pump 30 is exemplified. The vaporizing tubes 10 are arranged in parallel to each other in the left-right direction (the depth direction in FIG. 1; the direction perpendicular to the alignment direction of main tubes 12 described later). The support frame 20 supports the vaporizing tube 10 from the outside. The pump 30 supplies LNG into each vaporizing tube 10.

  Each of the vaporization tubes 10 is made of a metal material having high thermal conductivity such as aluminum or an aluminum alloy, and forms a meandering flow path as shown in FIG. 4. In this meandering flow path, LNG vaporization, that is, natural gas ( Hereinafter referred to as “NG”) and further heating of NG. Specifically, each vaporizing pipe 10 includes a plurality of main pipes 12 arranged in a horizontal direction (front-rear direction in this embodiment; left-right direction in FIG. 4), and upper ends and lower ends of main pipes 12 adjacent to each other. It is comprised with the U-shaped connection pipe 14 which connects mutually alternately, and the turbulent flow promotion material with which it loads in the main pipe 12 as mentioned later.

  Of each vaporization pipe 10, the lower end of the coldest pipe 12L which is the coldest main pipe is connected to a common inlet header 16 extending in the left-right direction (depth direction in FIG. 4). The inlet header 16 has an LNG supply port 16a at the center thereof, and the pump 30 is connected to the LNG supply port 16a. Similarly, the lower end of the highest temperature pipe 12H, which is the highest temperature main pipe, is connected to a common outlet header 18 extending in the left-right direction as shown in FIG. The discharge port 18a is provided.

  As shown in FIG. 4, the upstream portion of each vaporizing tube 10 constitutes an evaporation portion 10 a, and the downstream portion constitutes a heating portion 10 b. The evaporating unit 10a is a part that heats and evaporates the LNG by exchanging heat between the LNG flowing through the flow path formed therein and the outside air, and the heating unit 10b This is the part where NG is further heated. The boundary between the evaporation unit 10a and the heating unit 10b varies depending on the operating conditions of the apparatus, particularly the discharge flow rate of the pump 30. In the illustrated example, the flow rate at which the pump 30 serving as the liquefied natural gas supply means becomes the evaporation portion 10a up to a portion slightly downstream of the intermediate portion of each vaporizing tube 10 as shown in FIG. Then, the LNG is discharged.

  Each main pipe 12 includes a pipe main body 12a as shown in FIG. 5 and a plurality of fins 12b. Each fin 12b extends radially from the tube body 12a and promotes heat exchange between LNG or NG flowing in the tube body 12a and the outside air.

  The support frame 20 includes support columns 22 erected at four corners so as to surround the entire vaporization tube 10 from the outside, an upper frame 23 that connects upper ends of adjacent support columns 22, and a lower frame 24 that connects lower ends thereof. And an intermediate frame 26 that connects the intermediate parts.

  The turbulence promoting material is loaded in each main pipe 12. The turbulent flow promoting material may be any material that promotes the transition of LNG or NG (especially LNG) flowing through the main pipe 12 to turbulent flow. For example, the inner fin formed on the inner wall surface of the main pipe 12 But you can. In this embodiment, a twist tape 17 as shown in FIGS. 6 and 7 is loaded in each main pipe 12. The illustrated twist tape 17 forms a spiral flow path in the main pipe 12.

  The specific shape of the turbulent flow promoting material is not particularly limited. However, it is more preferable that the turbulent flow promoting material is loaded into the main pipe 12 so as to be in contact with the inner peripheral surface of the main pipe 12 as shown in FIG. This contact promotes heat exchange between the LNG or NG in contact with the turbulence promoting material and the main pipe 12 and contributes to a decrease in the surface temperature of the main pipe 12.

  This turbulence promoting material is loaded at least inside the coldest pipe 12L. The combination of loading of the turbulent flow promoting material into the coldest pipe 12L and the meandering flow path formed by the vaporizing pipe 10 produces an effect of improving the quality of frost as described later.

  The vaporizer further includes a defroster 40 as shown in FIG. 8 as a means for performing defrosting in the vaporizer tube 10. The defrosting device 40 blows defrosting gas on the surface of a specific main pipe (in the figure, the main pipe 12 up to the third main pipe 12 counted from the coldest pipe 12L) including the coldest pipe among the main pipes. It is what you attach.

  Specifically, the defrosting device 40 includes a plurality of front gas blowing pipes 42 and rear gas blowing pipes 44 extending in the horizontal direction, and these front gas blowing pipes 42 and rear gas blowing pipes 44. Are provided with a front gas supply pipe 46 and a rear gas supply pipe 48 for supplying the defrosting gas.

  The front gas blowing pipe 42 injects the defrosting gas supplied to the inside from the front side with respect to the coldest pipe 12L, and extends in the left-right direction of the vaporizer, that is, in the arrangement direction of the vaporization pipes 10. And it is arranged over a plurality of stages (four stages in the figure) arranged in the vertical direction. That is, in the vaporizer shown in FIG. 8 and the like, the four front gas blowing pipes 42 are arranged vertically spaced from each other.

  Each front gas spray tube 42 is provided with a plurality of gas injection ports 42a as shown in FIG. 9 along the longitudinal direction thereof. These gas injection ports 42a are through-holes penetrating the tube wall of the front gas blowing tube 42, and as shown in FIG. 5, between the tube main bodies 12a of the coldest tubes 12L and the tube main bodies 12a. Are formed at a plurality of positions at which the defrosting gas can be injected to the fins 12b.

  Each gas injection port 42a opens downward in the horizontal direction in this embodiment. Specifically, an axis inclined by a predetermined angle η (30 ° in the example) from the rear side from the vertical axis is used as the central axis 43, and is divided by a fixed injection angle θ (about 25 ° in the example) when viewed from the side. It has a shape and direction for injecting frost gas.

  As shown in FIG. 8, the angles η and θ enable the defrosting gas blown from the four-stage front gas blowing pipes 42 to be spread over the entire vertical direction of the lowest temperature pipe 12L. It is an angle to do. These angles η and θ are appropriately set according to specifications. For example, the gas injection port 42a may be opened in the horizontal direction or opened upward.

  On the other hand, the rear gas blowing pipe 44 is used for auxiliary blowing the defrosting gas supplied to the inside to the second main pipe 12 counted from the lowest temperature pipe 12L. The main pipes 12 that are adjacent to each other in the front-rear direction are arranged in two upper and lower stages. These rear gas spray pipes 44 are also provided with a plurality of gas injection ports 44a similar to the gas injection ports 42a along the longitudinal direction, but the injection angles are equal to the front and rear with the downward vertical axis interposed therebetween. (For example, 15 degrees). As shown in FIG. 8, this injection angle is an angle that enables the defrosting gas to be simultaneously blown to the main pipe 12 that sandwiches the rear gas blowing pipes 44 from the front and rear.

  The front gas supply pipes 46 are disposed on the left and right sides of the main body frame 20, and have a trunk pipe 46b and an introduction pipe 46c for introducing a defrosting gas into the trunk pipe 46b. The trunk pipe 46b is connected to the left end and the right end of each front gas blowing pipe 42 in a posture extending in the vertical direction. The introduction pipe 46c extends downward from an intermediate portion of the trunk pipe, and a defrosting gas supply source (for example, a blower) (not shown) is connected to the lower end of the introduction pipe 46c. Therefore, the defrosting gas supplied from the defrosting gas supply source is distributed to the front gas blowing pipes 42 through the introduction pipe 46c and the trunk pipe 46b.

  The rear gas supply pipes 48 are also arranged on the left and right sides of the main body frame 20, respectively, and are divided into upper and lower two-stage distribution pipes 48a, vertically extending trunk pipes 48b, and defrosting gas into the trunk pipes 48b. And an introduction pipe 48c for introduction. Each distribution pipe 48 a extends in the front-rear direction at each height position, and is connected to the left and right ends of each rear gas spray pipe 44. Each trunk pipe 48b is connected to the front end of each distribution pipe 48a. The introduction pipe 48c extends downward from an intermediate portion of the trunk pipe, and the defrosting gas supply source is connected to the lower end of the introduction pipe 48c. Accordingly, the defrosting gas supplied from the defrosting gas supply source is distributed from the introduction pipe 48c to the rear gas blowing pipes 44 through the trunk pipe 48b and further through the distribution pipe 48a. .

  In this invention, the kind of defrosting gas is not ask | required. The defrosting gas may be air or a gas that does not affect the properties of the vaporizing tube 10 (for example, an inert gas such as nitrogen gas). The temperature of the defrosting gas is not particularly limited. This temperature is preferably low enough not to interfere with the operation of the vaporizer. Specifically, a room temperature region (for example, 0 ° C. or more and 40 ° C. or less) is sufficient. Further, the number and arrangement of the gas spray pipes can be freely set according to the size of the vaporization pipe and the like.

  Next, the operation of this vaporizer will be described.

  The pump 30 supplies LNG into the inlet header 16. This LNG is divided into the vaporization tubes 10 from the inlet header 16 and meanders in the vaporization tubes 10, and the temperature rises by exchanging heat with the outside air via the vaporization tubes 10 during the meandering. When it reaches, it is vaporized to become natural gas. The region of the vaporizing tube 10 until the vaporization is completed corresponds to the evaporation unit 10a. In the heating section 10b on the downstream side, the natural gas is further heated to near normal temperature, merged at the outlet header 18, and then discharged through the NG discharge port 18a.

  In this apparatus, unlike the conventional vaporization apparatus in which a plurality of heat transfer tubes consisting only of straight pipes are arranged side by side, LNG needs to be evaporated and heated in a meandering flow path having a very long passage length. The temperature gradient of LNG in each main pipe 12 that forms the meandering flow path can be kept small. In particular, for the coldest pipe 12L, the apparatus can be operated so that the temperature of the LNG is low (for example, −120 ° C. or lower) in the entire region from the lower end to the upper end. In addition, since the turbulent flow promoting material that promotes the turbulent flow of LNG is provided in the coldest pipe 12L, heat exchange between the LNG and the coldest pipe 12L is promoted, whereby the coldest pipe. The surface temperature of 12L is kept low throughout the entire vertical direction.

  Thus, the coldest pipe 12L in which the low temperature region is formed long in the vertical direction has a good quality (so-called powder-like) frost attached to the surface thereof. This type of frosting occurs when moisture in the outside air is cooled in the vicinity of the tube surface and solidifies into particles. When the tube surface temperature is relatively high (for example, in the vicinity of 0 ° C.), frost grows using the particles as seeds and cannot be easily removed. However, if the surface temperature of the cryogenic tube 12L is maintained at a sufficiently low temperature as described above, all the moisture in the air in the vicinity thereof becomes fine crystals and adheres to the tube surface in a so-called powder shape.

  Therefore, in this apparatus, it is possible to easily remove the frost by simply blowing the defrosting gas from the defrosting apparatus 40 against the high-quality frost. Specifically, the defrosting gas is sprayed from the gas spray pipes 42 and 44 to the specific main pipe 12 including the coldest pipe 12L, so that frost attached to the main pipe 12 is generated. Blown off. Moreover, this defrosting does not require heating, and the defrosting gas may be at room temperature (for example, 0 ° C. or more and 40 ° C. or less), so that it is not necessary to stop the operation of the vaporizer for the defrosting. This dramatically increases the operating efficiency of the vaporizer. That is, the defrosting by this gas spray makes the conventional watering operation unnecessary or significantly reduces the frequency. As a result, the running cost of the apparatus is reduced and the operating efficiency is improved.

  In the conventional parallel type vaporizer, it is possible to provide a turbulent flow promoting material in the heat transfer tube, but it is practically difficult to realize the same defrosting as above. In such a conventional parallel type vaporizer, since the temperature gradient in the vertical direction is large, there are only a few regions in which a low temperature state can be secured, and high quality frost cannot be expected. Even if good quality frost adheres, the area is very small. Therefore, even if the high quality frost is removed, the heat transfer efficiency cannot be increased effectively, and frost grows in other areas. That is, in the present invention, the defrosting gas is blown only by a combination of a main pipe and a connecting pipe that form a meandering flow path including the evaporation section, and at least a turbulent flow promoting material loaded in the coldest pipe. It is possible to defrost by.

  Experiments for verifying the effects of the examples and comparative examples according to the present invention and the conventional example were conducted. The contents of each example are as follows.

In the embodiment and comparative example of the present invention, a vaporizing tube 10 having five main pipes 12 as shown in FIG. 10 is used. In the embodiment, the main tape 12 is loaded with the twist tape 17 as shown in FIGS. 6 and 7, and in the comparative example, the twist tape 17 is not loaded. Then, liquid nitrogen (hereinafter sometimes referred to as “LN ₂ ”) or LNG is supplied into the vaporization tube 10 as an experimental vaporization target liquid, and at each portion # 1 to # 21 shown in the figure at that time. The tube temperature is measured, and the frosting state in the lowest temperature tube 12L is observed.

On the other hand, as a conventional example, a vaporizer in which three heat transfer tubes 80A, 80B, 80C as shown in FIG. 11 are arranged in parallel is used. The lower ends of the heat transfer tubes 80A, 80B, 80C are connected to a common lower header 82, and the upper ends are connected to a common upper header 84. Then, liquid nitrogen or LNG is supplied to the lower header 82 as a vaporization target fluid, and is branched from the lower header 82 to the heat transfer tubes 80A to 80C to be vaporized in the heat transfer tubes. The nitrogen gas thus generated (indicated as “N ₂ ” in FIGS. 10 and 11) or natural gas joins the upper header 84 and is discharged out of the system. At this time, the tube temperatures at the respective parts # 30 to # 39 shown in the figure are measured, and the frosting state at the lower portion of the heat transfer tube 80B is observed.

  FIG. 12 shows the tube temperature at each site after the lapse of 2 hours from the start of the supply of liquid nitrogen into the vaporization tube in the example and the comparative example. As is apparent from FIG. 12, in the embodiment in which the twist tape 17 is loaded in the coldest pipe 12L, the low temperature state of −120 ° C. or lower is maintained over the entire area (# 2 to # 5) of the coldest pipe 12L. On the other hand, in the comparative example in which the twist tape 17 is omitted, the tube temperature in the upper part (# 4 and # 5) of the coldest tube 12L cannot fall below -100 ° C.

  On the other hand, FIG. 13 shows the measurement result of the temperature distribution in the conventional example. In this conventional example, since the apparatus is designed so that the vaporization of LNG is completed in the straight heat transfer tube, the temperature gradient is particularly large at the lower portion of the heat transfer tube (# 31 to 33). At # 32, the heat transfer tube temperature has already reached around 0 ° C. Therefore, in this conventional example, the low temperature region cannot be secured long vertically.

  The difference in the temperature state in each example as described above causes a difference in the quality of frost attached to the periphery of the coldest tube 12L and the heat transfer tube 80B. Specifically, in the heat transfer tube 80B according to the conventional example, the frosting thickness increases with the passage of time from the start, and after 4 hours, it exceeds 10 mm and normal operation becomes difficult. On the other hand, in the coldest pipe 12L, the frost attached to the surface is of good quality and the frost easily falls by the air blowing by the defrosting device 40, so that normal operation is continued for a long time. Is possible.

It is a side view of the LNG vaporization apparatus which concerns on embodiment of this invention. It is a front view of the said vaporization apparatus. It is a top view of the said vaporization apparatus. It is a side view of each vaporization pipe | tube included in the said vaporization apparatus. It is a cross-sectional top view which shows the arrangement | sequence state of the main pipe | tube contained in each said vaporization pipe | tube. It is a perspective view of the twist tape loaded in the said main pipe. It is a cross-sectional side view which shows the loading state of the twist tape in the said main pipe. It is a schematic diagram which shows arrangement | positioning of the gas spray pipe with respect to the said vaporization pipe | tube. It is a partial cross section side view which shows the gas spraying state by the said gas spraying pipe. It is a schematic diagram which shows the temperature measurement site | part in the Example and comparative example which concern on this invention. It is a schematic diagram which shows the temperature measurement site | part in a prior art example. It is a graph which shows the measurement result of the temperature in the said Example and the said comparative example. It is a graph which shows the measurement result of the temperature in the said prior art example. It is a graph which shows the time change of the frost formation thickness in each said example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vaporization pipe | tube 10a Evaporating part 10b Heating part 12 Main pipe 12H Highest temperature pipe 12L Minimum temperature pipe 14 Connection pipe 17 Twist tape (turbulent flow promotion material)
DESCRIPTION OF SYMBOLS 30 Pump 40 Defroster 42 Front side gas spray pipe 42a Gas injection port of front side gas spray pipe 44 Rear side gas spray pipe 44a Gas injection port of rear side gas spray pipe

Claims (8)

An apparatus for vaporizing liquefied natural gas,
An evaporation section that forms a flow path through which the liquefied natural gas flows and heat-exchanges the liquefied natural gas flowing through the flow path and the outside air to evaporate the liquefied natural gas, and after the evaporation A vaporizing tube including a heating part for further heating the natural gas, and a defrosting device for removing frost adhering to the surface of the vaporizing tube,
The vaporizing pipe extends in the vertical direction and is connected to a plurality of main pipes arranged in a specific horizontal direction and upper ends or lower ends of the main pipes adjacent to each other alternately, thereby the evaporation section and the A connecting pipe that forms a meandering flow path including both of the heating parts, and the main pipe is provided inside the main pipe over the entire flow path direction of the coldest pipe that is the coldest main pipe among the main pipes. A turbulence promoting material that promotes turbulent flow of liquefied natural gas in the pipe,
The defrosting device removes frost adhering to the surface by blowing a defrosting gas onto the surface of a specific main pipe including at least the coldest pipe among the main pipes. Gas vaporizer. The liquefied natural gas vaporizer according to claim 1,
The defrosting device includes a gas blowing pipe into which the defrosting gas is introduced, and the gas blowing pipe is a gas for injecting the defrosting gas supplied to the outside. An apparatus for vaporizing liquefied natural gas having an injection port and disposed at a position where the defrosting gas injected from the gas injection port hits the surface of the specific main pipe. The liquefied natural gas vaporizer according to claim 2,
The liquefied natural gas vaporizer is characterized in that the gas spray pipes are arranged in a plurality of stages arranged in the vertical direction. The liquefied natural gas vaporizer according to claim 2 or 3,
Provided with a plurality of the vaporization tubes, these vaporization tubes are arranged in a direction orthogonal to the arrangement direction of the main tubes,
The gas blowing pipe extends in the arrangement direction of the vaporization pipes, and has a plurality of gas injection ports for blowing the defrosting gas to specific main pipes of the vaporization pipes. Liquefied natural gas vaporizer. In the liquefied natural gas vaporizer according to any one of claims 2 to 4,
The liquefied natural gas vaporizer is characterized in that the gas injection port of the gas spray pipe opens in the horizontal direction or downward in the horizontal direction. In the liquefied natural gas vaporizer according to any one of claims 2 to 4,
The liquefied natural gas vaporizer is characterized in that a gas injection port of the gas spray pipe opens upward from a horizontal direction. A step of supplying liquefied natural gas into the vaporization pipe and vaporizing the liquefied natural gas by heat exchange between the liquefied natural gas and outside air; and a defrosting step of removing frost adhering to the vaporization pipe by the vaporization A method for vaporizing liquefied natural gas,
In the step of vaporizing the liquefied natural gas, as the vaporization pipe, a plurality of main pipes extending in the vertical direction and arranged in a specific horizontal direction, and upper ends or lower ends of the main pipes adjacent to each other are alternately arranged. By connecting, a connecting pipe that forms a meandering flow path including both an evaporating section that heats and evaporates the liquefied natural gas and a heating section that further heats the natural gas after the evaporation, and the main pipe A turbulent flow promoting material that is provided inside the main pipe over the entire flow path direction of the coldest pipe, which is the coldest main pipe, and that promotes turbulent flow of liquefied natural gas in the main pipe Use
Vaporization of liquefied natural gas characterized in that, in the defrosting step, frost adhering to the surface is removed by blowing gas onto the surface of a specific main pipe including at least the coldest pipe among the main pipes. Method. In the method of vaporizing liquefied natural gas according to claim 7,
In the defrosting step, a vaporizing method for liquefied natural gas, wherein a defrosting gas having a temperature of 0 ° C. or higher and 40 ° C. or lower is sprayed on the surface of the specific main pipe.

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