JP5039846B1 - Vaporizer for liquefied gas - Google Patents

Abstract

A vaporizer according to the present invention causes vaporization of liquefied gas by heating a heating medium. The vaporizer comprises: heating medium containers (1, 2) which house a heating medium in such a way that said heating medium can be replenished; and a helical heat transfer pipe (3) which extends from the lower part to the top part of the heating medium containers (1, 2) and extends in such a way as to fold back at the bottom once again. The top end of the heat transfer pipe (3) is not fixed, only the lower end of the heat transfer pipe is supported by the heating medium containers (1, 2), and liquefied gas to be vaporized flows continuously to the heat transfer pipe (3) and is vaporized.

Description

  The present invention relates to a vaporizer that vaporizes and evaporates a liquefied gas such as nitrogen, oxygen, argon, LNG (liquefied natural gas), propane, etc., and supplies the vaporized gas to consumers.

  In addition to industrial gases such as liquefied nitrogen, liquefied oxygen, liquefied argon, and liquefied carbon dioxide, fuel gases such as LNG (liquefied natural gas) and LPG (liquefied propane gas) are stored in liquid tanks and vaporizers. Evaporating and supplying the gas in the form of gas is used as an important industrial technique for repeatedly storing and consuming liquefied gas in each industrial field. A variety of heating sources for the vaporizer can be used depending on the physical properties of the gas, but atmospheric air is generally used. In this case, liquefied nitrogen, liquefied oxygen and liquefied argon are stored at a low temperature of −180 ° C. or lower, liquefied carbon dioxide gas is −25 ° C. or lower, LNG is −160 ° C. or lower, and LPG is stored at a low temperature of −40 ° C. or lower. When evaporating and evaporating with a vaporizer, moisture in the atmosphere air is frozen and ice is accumulated in the heat transfer tube, so that the heat transfer resistance is remarkably increased. Therefore, for example, in an LNG satellite (referring to a medium-scale or small-scale LNG storage facility installed in a plurality of locations apart from a large LNG storage facility as a center), at least two vaporizers are installed in parallel. Two units are switched and operated every predetermined time (for example, 4 hours), and while one vaporizer is performing the vaporization operation, the other vaporizer that has frozen is stopped and the ice is melted. A vaporizer that uses a liquid medium such as seawater as a heating source is also known. Conventional vaporizers that use seawater or atmospheric air as a heating source are disclosed in, for example, Patent Documents 1 to 3 below.

  For example, in the case of a vaporizer that heats and vaporizes LNG, which is a typical liquefied gas, as seen in JP-A-5-203098 (Patent Document 1), a plurality of heat transfer tubes that allow LNG to pass therethrough and to them A so-called shell-and-tube heat exchanger composed of a chamber partitioned by a welded tube sheet was used. In this method, a plurality of heat transfer tubes were incorporated between the tube plates, seawater was flowed to the shell side, and LNG was heated to evaporate.

  Japanese Laid-Open Patent Publication No. 5-332499 (Patent Document 2) discloses a vaporizer called an open rack type, in which a plurality of heat transfer tubes having a double tube structure are connected in the vertical direction and welded to upper and lower manifolds. By fixing, a panel-like structure was formed as a whole, and seawater was sprinkled on the outside to heat and evaporate.

  Furthermore, Japanese Patent Laying-Open No. 2005-156141 (Patent Document 3) discloses a vaporizer that warms using atmospheric air, and is spaced apart in the vertical direction as schematically shown in FIG. A finned heat transfer tube 23 (fins not shown) are arranged in parallel between the manifolds 21 and 22. The LNG to be vaporized is introduced from the lower manifold 21, is evaporated by heat exchange with air while being distributed to the plurality of finned heat transfer tubes 23, and is merged and recovered by the upper manifold 22, and is passed through the outlet tube 24. To be used in places outside the figure. In FIG. 5, reference numeral 25 indicates a welded portion between the heat transfer tube 23 and the upper and lower manifolds 21 and 22.

  As described above, the carburetor according to the prior art is used by standing a plurality of pipes in common, and installing and fixing a partition chamber and a manifold above and below the pipe. The gas vaporized while rising in the heat pipe gathered in the upper manifold and the partition chamber, and was heated by outside air and drawn out.

  In the vaporizer disclosed in Patent Document 1, since the heating is heated with seawater, when a sufficient amount of seawater flows, the problem that seawater freezes due to LNG fed at a temperature close to −160 ° C. Although it does not occur, since the heat transfer tubes are welded and fixed to the upper and lower tube sheets, if the degree of heating changes depending on the amount of LNG fed, the heat transfer tubes expand and contract and thermal stress is applied to the welded portion with the tube sheets. As a result, if the feed amount continues to change, this thermal stress repeats, and finally the welded portion fixed to the tube sheet is destroyed due to thermal fatigue. Also, since there are a plurality of heat transfer tubes, if the liquid dispersion of LNG in this interior is poor, the temperature of each welded portion fixed to the tube plate will vary, causing distortion in the tube plate and accelerating the thermal fatigue. .

  A similar problem also occurs in the vaporizer described in Patent Document 2 in which a heat transfer tube is welded and fixed to a manifold corresponding to a tube sheet.

  On the other hand, in the air heating type vaporizer of Patent Document 3 shown in FIG. 5, since a low-temperature liquid close to −160 ° C. is introduced into the heat transfer tube 23 and is simultaneously heated with atmospheric air from the outside, Water is frozen on the surface of the heat transfer tube 23 (the frozen portion is indicated by a symbol FZ), and the heat transfer efficiency is significantly reduced. In addition, it is difficult to distribute LNG evenly through the plurality of heat transfer tubes 23 from the lower manifold 21 to the upper manifold 22, and particularly when the evaporation load is reduced by reducing the flow rate of LNG, FIG. As shown, the length of the icing portion FZ is different for each of the different heat transfer tubes 23, and a temperature difference occurs between the different heat transfer tubes 23, and the length of expansion and contraction of each heat transfer tube is also different due to the difference in temperature difference. . For example, when aluminum is used as the material of the heat transfer tube 23, a difference in expansion / contraction amount of 2.3 mm / m occurs when a temperature difference of 100 ° C. occurs, and a heat transfer tube made of stainless steel has a difference of 1.5 mm / m. A difference in the amount of expansion and contraction occurs, and a difference in the amount of expansion and contraction of 1.2 mm per meter occurs in the steel heat transfer tube. For this reason, excessive stress is applied to the welded portions 25 fixed to the manifolds 21 and 22, and often causes a problem that the welded portions 25 are cracked when the vaporizer is operated intermittently.

  In addition, since the liquefied gas vaporizer is designated as a gas facility of the High Pressure Gas Safety Act, the vaporizer must be subjected to a public open inspection of the welded part and internal configuration once every three years. A structure that can easily inspect the internal structure including the welded portion at the time of inspection is required.

JP-A-5-203098 JP-A-5-332499 JP 2005-156141 A

  In view of the above, a main problem to be solved by the present invention is to provide a carburetor that hardly causes problems such as breakage in a welded portion of a heat transfer tube even when repeated thermal stress is applied.

  Further, the supplementary problem of the present invention is that two identical vaporizers are installed alternately to reduce the heat exchange rate due to freezing of moisture on the surface of the heat transfer tube as in the case of heating with ambient air. It is to provide a vaporizer that does not require operation and de-icing.

  Furthermore, another supplementary problem of the present invention is to provide a carburetor having a structure that is easily subjected to public inspection of the welded portion and the entire internal structure as a gas facility subject to the High Pressure Gas Safety Law. .

  The present invention proposes and employs the following means in order to solve the above problems.

  That is, the present invention is a vaporizer that heats and vaporizes a liquefied gas with a heat medium, and includes a heat medium container that can be replenished with the heat medium, and extends from the lower part to the upper part of the heat medium container and again to the lower part. A liquefied gas to be vaporized in the heat transfer tube, the upper end portion of the heat transfer tube not being fixed, and only the lower end portion of the heat transfer tube supported by the heat medium container. A vaporizer is provided that continuously vaporizes the gas.

  According to the above configuration, the heat transfer tube has a spiral shape, and the heat transfer tube can absorb the change in length even if the cooling and heating are repeatedly expanded and contracted due to the fluctuation of the evaporation amount. Therefore, it is possible to avoid an excessive stress being applied to the support portion (joint portion) of the heat transfer tube with respect to the heat transfer medium container, and it is possible to eliminate or reduce problems such as breakage of the support portion. Moreover, the heat transfer area can be changed by adjusting the total length by adjusting the number of turns and the winding density of the heat transfer tube.

  Further, unlike the case of using atmospheric air or seawater, the heat transfer tube is heated at a temperature not lower than room temperature, for example, + 60 ° C. with a heat medium such as warm water. Therefore, freezing does not occur on the surface of the heat transfer tube. As a result, it is not necessary to place the frozen vaporizer on standby and defrost, so there is no need to install two vaporizers, and vaporization can be continued with only one. Moreover, compared to the case of heating with air or seawater, for example, when + 60 ° C hot water is used, the temperature difference between the heated side and the heated side increases, so the heat transfer area is greatly reduced, and the vaporizer is Can be made compact.

  Preferably, the heat transfer tube is configured such that the inner diameter increases stepwise from the upstream side to the downstream side. Thereby, even if the volume reaches 70 times or more in the process of changing the liquefied gas such as LNG from liquid to gas, the flow rate of the liquid or gas can be optimized according to the evaporation amount in the heat transfer tube.

  Preferably, the inner diameter of the heat transfer tube is stepwise so that the inner diameter cross-sectional area of the thickest portion on the downstream side is in the range of 1.5 to 10 times the inner diameter cross-sectional area of the thinnest portion on the upstream side. It is configured to be large.

  Preferably, the heat transfer medium container includes a bottom plate and a main body housing detachably joined to the bottom plate, and the upstream end and the downstream end of the heat transfer tube are fixed only to the bottom plate. Has been. According to this configuration, all the components incorporating the heat transfer tubes can be directly inspected and maintained simply by removing the covering main body housing from the bottom plate.

  Preferably, the upstream end portion and the downstream end portion of the heat transfer tube are respectively supported by the bottom plate via a cap, and the cap is connected to the upstream end portion or the first end via a first welded portion. While being joined to the downstream end, it is joined to the bottom plate via a second weld. According to this structure, the stress accompanying expansion and contraction of the heat transfer tube and the cap can be distributed to the first welded portion and the second welded portion, respectively, and stress concentration can be avoided.

  Preferably, the cap has a curved ceiling wall, the heat transfer tube passes through the ceiling wall of the cap, and the first welded portion has an obtuse angle with respect to the heat transfer tube and the ceiling wall of the cap. It is joined across. Also with this configuration, stress concentration on the welded portion can be more effectively avoided.

  Preferably, the heat medium container is provided with a heat medium introduction nozzle for supplying a heat medium therein, and the opening of the heat medium introduction nozzle is arranged in a circumferential direction of the outer peripheral wall of the heat medium container. A heat medium is sprayed along. Thereby, the heat exchange efficiency to the liquefied gas by a heat medium improves.

  Preferably, the heat medium container is provided with a heat medium overflow pipe that defines a liquid surface of the heat medium inside the heat medium container, and the heat medium that overflows beyond the upper end opening of the heat medium overflow pipe is disposed in the heat medium. It is configured to discharge to the outside of the container.

  Preferably, a gas leak detection means for detecting liquefied gas leaked from the heat transfer tube in the heat medium container is further provided. Thereby, it is possible to avoid the operation from being continued in a state where the gas has leaked.

  The vaporizer of the present invention is particularly suitable for vaporizing liquefied natural gas (LNG), but not only LNG vaporization, but also liquefied oxygen having a boiling point of −183 ° C., liquefied argon having −186 ° C., The present invention can also be applied to the case of vaporizing a liquefied gas stored in a liquid form at a low temperature, such as liquefied nitrogen at -196 ° C, propane at -42 ° C.

  Further features, operations, and effects of the present invention will become apparent from the embodiments described below with reference to the accompanying drawings.

It is a fragmentary longitudinal cross-sectional view which mainly shows the schematic structure of the vaporizer | carburetor which concerns on embodiment of this invention, and the structure of the heat exchanger tube coil in the inside. It is a fragmentary longitudinal cross-sectional view which mainly shows schematic structure of members other than the heat exchanger tube in the vaporizer. It is a cross-sectional view which shows schematic structure of the vaporizer. It is an expanded sectional view which shows the structure of the welding location in the same vaporizer. It is a schematic block diagram which shows the principal part in the conventional vaporizer | carburetor.

  1 to 4 show a configuration of a vaporizer for liquefied gas according to an embodiment of the present invention. The vaporizer mainly includes a bottom plate 1, a shell-like main body housing 2, a heat transfer tube 3, and a heat exchanger. A medium introduction nozzle 4, a heat medium overflow pipe 5, a heat medium drain pipe 6, and a gas leak detection pipe 7 are included. 1 to 4, the thickness of the main body housing 2, the heat transfer pipe 3, the heat medium introduction nozzle 4, the heat medium overflow pipe 5, the heat medium drain discharge pipe 6, etc. is omitted for the sake of simplicity. ing. In the following description, the liquefied gas to be vaporized is liquefied natural gas (LNG) and the heating medium is warm water. However, the present invention is not limited to these.

  The bottom plate 1 is made of, for example, stainless steel, and has a plurality of heat transfer tube insertion holes 1a and 1b (two heat transfer tube insertion holes in FIG. 1) and a plurality of bolt holes 1c. The bottom plate 1 may also serve as a scaffolding plate for the LNG satellite.

  The main body housing 2 is made of, for example, stainless steel, the lower end is open, and the upper end is closed by a partially spherical or curved ceiling wall 2a. Therefore, the main body housing 2 has a substantially bell-shaped form. An annular flange 2 b is integrally formed on the outer periphery of the lower end of the opening of the main body housing 2, and a bolt hole 2 c corresponding to the bolt hole 1 c of the bottom plate 1 is provided in the flange 2 b. The main body housing 2 and the bottom plate 1 are fixed in a sealed state to each other by bolts (not shown) inserted into the respective bolt holes 1c and 2c. Therefore, the main body housing 2 can be easily detached from the bottom plate 1 by removing the bolts not shown, and the internal structure can be easily inspected visually. In the present embodiment, the bottom plate 1 and the main body housing 2 define a heat medium container for accommodating a heat medium such as warm water. Although not shown, an appropriate sealing material is interposed between the flange 2b of the main body housing 2 and the bottom plate 1 so that the sealed state is maintained.

  As shown in FIG. 1, the heat transfer tube 3 is drawn into the inside of the main body housing 2 through one heat transfer tube insertion hole 1 a of the bottom plate 1, extends upward in a spiral shape, and then turns downward to return to the bottom plate 1. It leads out outside through the other heat exchanger tube insertion hole 1b. As a result, even if the heat transfer tube 3 expands and contracts due to a temperature change, it can be sufficiently absorbed by the spirally extending portion, and stress is not easily transmitted to the connecting portion to the bottom plate 1 (details of the structure will be described later). It has become.

  In the illustrated embodiment, the heat transfer tube 3 gradually increases in diameter as it extends from the upstream side to the downstream side, and extends from the upstream side small diameter portion 3a and from the small diameter portion 3a to the folded top. A diameter portion 3b and a large diameter portion 3c extending from the medium diameter portion 3b toward the bottom plate 1 are included. The small-diameter portion 3a and the medium-diameter portion 3b are connected by a reducer 3d (a known element for connecting pipes having different diameters), and the medium-diameter portion 3b and the large-diameter portion 3c are connected by a reducer 3e. Has been. Specifically, the small diameter portion 3a is, for example, a stainless steel tube having an inner diameter of 27.2 mmΦ, and the medium diameter portion 3b is, for example, a stainless steel tube having an inner diameter of 35.5 mmΦ or an inner diameter of 52.7 mmΦ (the cross-sectional area ratio is 1.7 times to 3. The large diameter portion 3c is a stainless steel pipe having an inner diameter of 65.9 mmΦ (increase the cross-sectional area ratio from 1.6 to 3.4 times that of the medium diameter portion 3b). It is. However, the inner diameter of the heat transfer tube 3 may be increased in two stages (in this case, the cross-sectional area ratio is increased 5.9 times from the inner diameter 27.2 mmΦ to the inner diameter 65.9 mmΦ) at four stages or more. The inner diameter may be increased separately.

  The small diameter portion 3a of the heat transfer tube 3 is connected to a pipe extending from, for example, an LNG storage tank at the upstream end thereof. On the other hand, the large diameter portion 3c of the heat transfer tube 3 is connected to a pipe connected to, for example, a natural gas utilization site at the downstream end thereof.

  As shown in FIGS. 2 and 3, the heat medium introduction nozzle 4 is made of, for example, a stainless steel pipe, is connected to a pipe extending from a heat medium supply source (warm water supply source) (not shown), and penetrates the bottom plate 1. Extending upward. The upper end of the heat medium introduction nozzle 4 is opened along the circumferential direction of the outer peripheral wall at the lower part of the main body housing 2, and the heat medium is injected so that the heat medium introduced into the main body housing 2 becomes a vortex. It is supposed to be. As the heating medium, liquid such as warm water, ethanol or ethylene glycol can be used, but it is preferable to use warm water in consideration of cost and ease of handling.

  The heat medium overflow pipe 5 is made of, for example, a stainless steel pipe, and extends through the bottom plate 1 in a sealed state. The upper end opening 5 a of the heat medium overflow pipe 5 is located in the vicinity of the ceiling wall 2 of the main body housing 2, and the heat medium that overflows when the heat medium is sequentially supplied from the heat medium introduction nozzle 4 is discharged to the outside. The heat medium discharged through the heat medium overflow pipe 5 is reheated by a reheating means (not shown) and is circulated again to a heat medium supply source (not shown).

  The heat medium drain pipe 6 is for discharging the internal heat medium before the main body housing 2 is removed from the bottom plate 1 and the inside is inspected and is sealed through the through hole of the bottom plate 1. It communicates with the inside of the main body housing 2 in a state. The heat medium drain pipe 6 is made of, for example, a stainless steel pipe.

  The gas leak detection pipe 7 is provided to serve as a check nozzle when a liquefied gas such as LNG leaks inside the main body housing 2, and its upper end 7 a is the upper end opening 5 a (heat The liquid level of the medium is defined) and the ceiling wall 2 a of the main body housing 2. The liquefied gas leaked inside the main body housing 2 is converted into a gas and led out to the outside by the gas leak detection pipe 7 and detected by a sensor (not shown) connected to the gas leak detection pipe 7. When a leak of liquefied gas is detected, inspection and repair are performed.

  Next, the connection structure with respect to the baseplate 1 of the heat exchanger tube 3 is demonstrated. The heat transfer tube 3 is connected to the bottom plate 1 at two locations, that is, at the positions of the heat transfer tube insertion holes 1a and 1b, but the basic connection structure is the same, although there is a difference in diameter. Therefore, as a representative example, a connection structure in the heat transfer tube insertion hole 1a of the small diameter portion 3a will be described with reference to FIG.

  As shown in FIG. 4, the heat transfer tube insertion hole 1 a is closed by a cap 8, and the small-diameter portion 3 a of the heat transfer tube 3 passes through the central portion of the hemispherical or curved ceiling wall 8 a of the cap 8. Yes. The small diameter portion 3a of the heat transfer tube 3 and the ceiling wall 8a of the cap 8 are joined by a welded portion 9a, and the skirt portion of the cap 8 and the bottom plate 1 are joined by a weld bead 9b. As a result, since the heat transfer tube 3 and the cap 8 are joined and fixed at different points, the expansion and contraction of the heat transfer tube 3 and the expansion and contraction of the cap 8 are separately free, and the two thermal stresses are caused by two welds 9a, 9b. In addition, with respect to the welded portion 9 a to the heat transfer tube 3, a stress dispersion effect due to the hemispherical or curved ceiling wall 8 a in the cap 8 additionally acts. Therefore, coupled with the expansion / contraction absorption effect due to the heat transfer tube 3 having a spiral structure, stress concentration on the welds 9a and 9b does not occur. The cap 8 is preferably made of, for example, stainless steel similar to the heat transfer tube 3.

  When the vaporizer having the above configuration is operated, hot water of about + 60 ° C., for example, is supplied to the main body housing 2 through the heat medium introducing nozzle 4 to substantially fill the inside of the main body housing 2. The supplied hot water rises as a vortex in the main body housing 2, and the excess hot water is discharged to the outside through the heat medium overflow pipe 5 and recirculated to the heat medium supply source. Is done.

On the other hand, LNG that is a liquefied gas once rises in the heat transfer tube 3 wound in a spiral shape, and then changes from a liquid to a gas by being heated by hot water that is a heating medium while descending. In the process, LNG, which is a liquid, increases its volume by about 70 times when it is changed to a gas of −145 ° C. at 0.3 MPaG. However, as described above, since the inner diameter of the heat transfer tube 3 increases stepwise, the resistance to the flow of fluid does not increase unduly, and an optimal flow rate of LNG or vaporized gas is ensured. The vaporized natural gas is finally heated to near normal temperature inside the heat transfer tube 3 and discharged.

For example, if hot water of + 60 ° C. is used to evaporate 600 kg / h of LNG, the surface area of the heat transfer tube 3 needs to be about 13 m ^2, but if this is heated with air or seawater, The area needs to be about twice or more, and the height of the equipment increases and the installation area also increases. Therefore, according to this embodiment, it is possible to reduce the size of the vaporizer and the installation area.

As mentioned above, although embodiment of this invention was described, it is as follows when the effect by the said embodiment is put together.
(1) Since the heat transfer tube 3 has a spiral shape, the expansion and contraction of the heat transfer tube due to a temperature change can be absorbed, stress is not easily applied to the welded portion, and the welded portion is not easily broken. In particular, when a single spiral heat transfer tube is used as in the illustrated embodiment, there is no difference in thermal stress between heat transfer tubes as in the case of using a plurality of heat transfer tubes, and thermal fatigue is less likely to occur. Moreover, by adopting the spiral heat transfer tube 3, the heat transfer area can be easily changed by adjusting the total heat transfer tube length by adjusting the number of turns and the winding density of the spiral.
(2) Since the joining of the heat transfer tube 3 to the bottom plate 1 is divided into two welded portions 9a and 9b via the cap 8, the thermal stress accompanying the expansion and contraction of the heat transfer tube 3 and the cap 8 is caused to interfere. Can be dispersed without any problem. Moreover, since the stress dispersion effect by the hemispherical or curved ceiling wall 8a in the cap 8 acts additionally on the welded portion 9a to the heat transfer tube 3, the stress dispersion effect as a whole is further enhanced.
(3) Even if the volume reaches 70 times or more in the process of changing LNG from liquid to gas, the inner diameter of the heat transfer tube 3 is increased stepwise according to the evaporation amount in the heat transfer tube 3, The flow rate of liquid or gas can be optimized.
(4) Since a heat medium such as warm water is used, the temperature difference between the heating side and the heated side becomes large, and the heat transfer area can be reduced to make it compact. In addition, since a heating medium is used, it is not necessary to wait for a frozen vaporizer to be defrosted, so there is no need to install two vaporizers, and vaporization can be performed with only one.
(5) Since the main body housing 2 covering the heat transfer tube 3 is detachably joined to the bottom plate 1 in a bell shape or a cap shape, and the heat transfer tube 3 is welded to only the bottom plate 1, the main body housing 2 is attached to the bottom plate. Only by removing from 1, the state of the heat transfer tube 3 and the welded portion can be easily visually inspected and maintained.

  The present invention can be variously modified without departing from the basic idea. For example, in the illustrated embodiment, the material such as the heat transfer tube 3 is made of stainless steel. However, when it is desired to reduce the weight, it can be made of aluminum or an aluminum alloy. In the illustrated embodiment, one heat transfer tube 3 is used. However, a plurality of spiral heat transfer tubes may be provided so as not to interfere with each other in arrangement, and each heat transfer tube may be provided with respect to the bottom plate 1. A joining structure as shown in FIG. 4 can be employed. Furthermore, the vaporizer of the present invention is not only for vaporizing LNG but also for storing liquid oxygen having a boiling point of −183 ° C., liquefied argon of −186 ° C., liquefied nitrogen of −196 ° C., propane of −42 ° C. in a liquid state at low temperature. The present invention is also applicable when vaporizing the liquefied gas.

DESCRIPTION OF SYMBOLS 1 Bottom plate 2 Main body housing 2a Main body housing ceiling wall 2b Main body housing flange 3 Heat transfer tube 3a Heat transfer tube small diameter portion 3b Heat transfer tube medium diameter portion 3c Heat transfer tube large diameter portion 4 Heat transfer nozzle 4a Heat transfer nozzle Opening 5 Heat medium overflow pipe 5a Upper end opening of heat medium overflow pipe 6 Heat medium drain pipe 7 Gas leak detection pipe 7a Upper end of gas leak detection pipe 8 Cap 8a Ceiling walls 9a, 9b Welded portion

Claims (9)

A vaporizer for heating and vaporizing a liquefied gas with a heat medium, a heat medium container in which the heat medium is replenished, and a spiral extending from the lower part to the upper part of the heat medium container and extending back to the lower part A heat transfer tube, and the heat medium container includes a bottom plate and a main body housing detachably joined to the bottom plate, and does not fix the upper end of the spiral heat transfer tube, the upstream end and the downstream end of the spiral heat exchanger tube are welded only to the bottom plate, by removing the body Haujin grayed from the bottom plate, the welded portion with respect to the bottom plate of the heat transfer tube configured to cut with Inspect visually and to vaporize flowing liquefied gas to be vaporized in the heat transfer tube continuously vaporizer.   The carburetor according to claim 1, wherein the heat transfer tube has an inner diameter that increases stepwise from the upstream side to the downstream side.   The inner diameter of the heat transfer tube increases stepwise so that the inner diameter cross-sectional area of the thickest portion on the downstream side is in the range of 1.5 to 10 times the inner diameter cross-sectional area of the narrowest portion on the upstream side, The vaporizer according to claim 2. The upstream end portion and the downstream end portion of the heat transfer tube are respectively supported by the bottom plate via a cap, and the cap is connected to the upstream end portion of the heat transfer tube via the first welded portion. The vaporizer according to claim 1 , wherein the vaporizer is joined to the downstream end and joined to the bottom plate via a second weld. The cap has a curved ceiling wall, the heat transfer tube passes through the ceiling wall of the cap, and the first welded portion straddles the obtuse angle of the heat transfer tube and the ceiling wall of the cap. The vaporizer according to claim 4 , wherein the vaporizer is bonded.   The heat medium container is provided with a heat medium introduction nozzle for supplying a heat medium therein, and the opening of the heat medium introduction nozzle is heated along the circumferential direction of the outer peripheral wall of the heat medium container. The vaporizer according to claim 1, which injects a medium.   The heating medium container is provided with a heating medium overflow pipe that defines the liquid level of the heating medium inside the heating medium container, and the heating medium overflowing beyond the upper end opening of the heating medium overflow pipe is disposed outside the heating medium container. The vaporizer according to claim 1, wherein   The vaporizer according to claim 1, further comprising gas leak detection means for detecting liquefied gas leaked from the heat transfer tube in the heat medium container.   The vaporizer according to claim 1, wherein the liquefied gas is liquefied natural gas (LNG) and is supplied to an LNG satellite.

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