JP2004092899A - Air heating type vaporizer for liquefied gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten an operating performance of a vaporizer by effectively solving problems of frosting. <P>SOLUTION: This vaporizer 10 comprises an evaporation part 12A and a heating part 12B with a plurality of heat transfer tubes 20, 26, and LNG is distributed through the heat transfer tubes 20, 26 of the parts 12A, 12B and heat-exchanged with air, so as to gasify LNG. Each of the heat transfer tubes 20, 26 has an integral structure comprising a tube body 21a, a radial fin 21b extending on a periphery in a tube axial direction, and an outer tube part 21c (outer tube element) surrounding the tube body 21a from the outside of the fin 21b, and installed on a base 34 commonly serving as a duct in an upright condition. Atmospheric air (air) is forcedly introduced in a space between the tube body 21a and the outer tube part 21c of the respective heat transfer tubes 20, 26 via the base 34 by driving a blower 36. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air-heated vaporizer for vaporizing a low-temperature liquefied gas such as liquefied natural gas (LNG).
[0002]
[Prior art]
As the above-mentioned air-heated vaporizer, for example, the one disclosed in Patent Document 1 is known.
[0003]
The vaporizer disclosed in this publication is composed of an evaporator and a heater. First, LNG is gasified by exchanging heat with air in the evaporator (natural gas (NG)). The NG is heated to a predetermined temperature by exchanging the NG with air in the heating unit.
[0004]
A plurality of heat transfer tubes with parallel flow fins extending vertically, that is, heat transfer tubes having radial fins extending in the tube axis direction around the tube main body are provided in parallel in the evaporating section, and these transfer tubes are provided through an inlet header. LNG is distributed to the heat pipes, and each heat transfer pipe is used for heat exchange. On the other hand, the heating section is provided with a meandering heat transfer tube in which a plurality of vertically extending heat transfer tubes with parallel flow fins are connected in series. Heat exchange is performed while being continuously passed through the heat transfer tube.
[0005]
[Patent Document 1]
JP 2000-146090 A
[Problems to be solved by the invention]
It is known that frost forms on each heat transfer tube of an evaporator in an air temperature type vaporizer. Such frost accumulates around the fins with the passage of time, and as a result, air tends to flow away from the fins, gradually reducing the heat exchange capacity. Therefore, conventionally, after a lapse of a certain time from the start of operation, the vaporizer is temporarily stopped to perform defrosting work, and when continuous operation is required, the two vaporizers are alternately operated at regular time intervals. That is being done.
[0007]
However, if the operation is frequently stopped for the defrosting operation, the operation efficiency is poor, and it is uneconomical to alternately operate the two vaporizers. Therefore, it is desired to solve the above-mentioned problem of frost formation and enhance the operation performance of the vaporizer.
[0008]
The present invention has been made in view of the above problems, and has as its object to effectively solve the problem of frost formation and improve the operation performance of a carburetor.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a plurality of heat transfer tubes having radial fins extending in the tube axis direction around a tube main body, and liquefied gas is passed through each of the heat transfer tubes to exchange heat with air. In the liquefied gas air-heated vaporizer that generates a gaseous body by causing the heat transfer tubes to be provided, each of the heat transfer tubes includes: The apparatus is provided with forced flow forming means for forcibly introducing air into the space between the outer cylinder and the space.
[0010]
According to this configuration, the air can flow at a high speed concentrated around the fins of each heat transfer tube, thereby improving the heat transfer efficiency and preventing the occurrence of frost due to the heat exchange between the liquefied gas and the air. Effectively suppressed. As a result, the state where the heat transfer area of the heat transfer tube is effectively secured is maintained for a long time.
[0011]
In this configuration, the radial fins of the heat transfer tube are preferably connected to the outer cylinder, and the heat transfer tube has an integral structure in which the inner peripheral surface of the outer cylinder is joined to the tip of the radial fin. It is more preferable to do so.
[0012]
According to this configuration, it is possible to increase the substantial heat transfer area of the heat transfer tube and improve the heat exchange capacity.
[0013]
Further, in the above structure, the forced flow forming means includes a blower and a duct, and the heat transfer tube and the outside are connected in a state where the space between the heat transfer tube and the outer cylinder communicates with the inside of the duct. It is preferable that the cylinder is assembled to the common duct.
[0014]
According to this configuration, it is possible to forcibly introduce air into the space between each heat transfer tube and the outer cylinder with a simple and rational configuration using a common blower and a duct.
[0015]
In this case, it is preferable that the forced flow forming means is configured to pressure-feed (pusher) air into the duct.
[0016]
That is, a method (suction method) in which air is forced into the space between each heat transfer tube and the outer cylinder by sucking air in the duct may be adopted. However, in this case, the cold air after the heat exchange passes through the duct or the blower, so that it is conceivable that frost may be formed on these parts. Is more advantageous.
[0017]
An evaporating unit having a plurality of the heat transfer tubes connected in parallel, distributing and introducing the liquefied gas to each heat transfer tube to gasify the liquefied gas, and a plurality of the heat transfer tubes connected in series And a heating unit for raising the temperature of the gaseous body derived from the evaporating unit is provided, and the heat transfer tubes and the outer cylinder of the evaporating unit and the heating unit are assembled to the common duct. Is also good.
[0018]
According to this configuration, in both the evaporating section and the heating section, the occurrence of frost due to the heat exchange between the liquefied gas and the air is effectively suppressed. Therefore, the liquefied gas can be gasified efficiently and the temperature can be increased efficiently with a rational configuration in which the forced flow forming means is shared.
[0019]
In this case, the evaporating unit and the heating unit are provided in order from the upstream side in the direction of air pressure supplied by the blower, and a guide member that guides air to a portion corresponding to the evaporating unit is provided in the duct. Is preferred.
[0020]
According to this, air is easily introduced into the evaporating section where frost is likely to occur, while using the forced flow forming means in common. Therefore, it is possible to reliably introduce air into the space between each heat transfer tube of the evaporator and the outer cylindrical body, and to suppress the occurrence of frost.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a schematic view showing an air-heated liquefied gas vaporizer according to the present invention. The liquefied gas air-heated vaporizer 10 (hereinafter abbreviated as vaporizer 10) shown in this figure is roughly divided into an evaporator 12A and a heater 12B, and is supplied from a tank (not shown) through a supply pipe 14. Liquefied natural gas (LNG) is first gasified (referred to as NG) by subjecting it to heat exchange with air in the evaporating section 12A, and is further subjected to heat exchange with air in the heating section 12B to reach a predetermined temperature. The temperature is raised, and thereafter, it is configured to be supplied to a consumption area or the like through the discharge pipe 32.
[0023]
A plurality of heat transfer tubes 20 and 26 extending in the vertical direction are provided in the evaporating unit 12A and the heating unit 12B in an aligned state. Specifically, assuming that the horizontal direction in the figure is a column direction and the direction perpendicular to the paper surface of the figure is a row direction, as shown in FIG. Heat transfer tubes 20 are provided, and a total of 21 heat transfer tubes 26 are provided in the heating unit 12B in an array of 3 rows and 7 columns.
[0024]
The configuration of each of the heat transfer tubes 20 and 26 is common. Specifically, as shown in FIG. 4, a pipe main body 21a through which LNG flows, a plurality of radial fins 21b extending in the pipe axis direction on the outer peripheral surface, and a radially extending fin 21b extending from the outside in the pipe axis direction. It has a double pipe structure having an outer cylindrical portion 21c (outer cylindrical body) having a circular cross section. The space between the tube main body 21a and the outer cylinder part 21c is opened in the up-down direction.
[0025]
Each of the heat transfer tubes 20 and 26 is integrally formed by extrusion using aluminum or an aluminum alloy having good heat conductivity as a material. In the present embodiment, for example, the tube main body diameter is 30 mm, and the outer tube diameter is 210 mm. The thickness is 3 mm, eight radial fins 21b are provided around the pipe body 21a at an angular interval of 45 °, and the total height of the heat transfer pipe is about 6 m.
[0026]
Each of the heat transfer tubes 20 (tube main body 21a) belonging to the evaporating section 12A has a lower end connected to a branch pipe 18 branched from the inlet header 16, and in the present embodiment, the inlet header 16 has the above-described line. Three branch pipes 18 corresponding to the numbers are provided, and the heat transfer pipes 20 belonging to a common row among the heat transfer pipes 20 are connected to the same branch pipes 18 respectively. On the other hand, the upper end of each heat transfer tube 20 (tube main body 21a) is connected to a common collecting tube 22 for each of the members belonging to each row. In other words, LNG introduced through the supply pipe 14 is distributed and introduced to each heat transfer tube 20 through the inlet side header 16 and the branch tube 18, and gasified LNG (that is, NG) is passed through each heat transfer tube 20 to each line. Each time, it collects in the collecting pipe 22 and guides it to the heating unit 12B via the connecting pipes 24 connected to these collecting pipes 22, respectively.
[0027]
Of the heat transfer tubes 26 belonging to the heating unit 12B, the transfer tube is provided at one end side (left end in the figure) of each row, that is, at the upper end of the heat transfer tube 26 (tube main body 21a) on the NG receiving side. The outlet header 30 is connected to the lower end of the heat transfer tube 26 at the other end of each row, and to the lower end of the heat transfer tube 26 at the discharge side. Then, as shown in FIG. 1, the heat transfer tubes (tube main bodies 21 a) belonging to each row are connected in series via a connection pipe 28, so that the NG generated in the evaporating unit 12 </ b> A is passed through the transfer pipe 24 to each row. After being introduced into the heat transfer tubes 26 on one end side and sequentially passing through the heat transfer tubes 26 belonging to the row, they are collected in the outlet side header 30 and led out through the discharge pipe 32.
[0028]
As shown in FIGS. 1 and 2, the heat transfer tubes 20 and 26 of the evaporating unit 12A and the heating unit 12B are provided in a state of being supported by a base 34 also serving as a ventilation duct.
[0029]
As shown in FIG. 2, the base 34 has a hollow structure that is flat in the vertical direction, and takes in outside air (air) into the inside thereof by the operation of an electric blower 36 attached to the side surface thereof. It is configured to feed in the direction indicated by the white arrow.
[0030]
On the base, the evaporating section 12A and the heating section 12B are arranged side by side from the upstream (left side in the figure) in the direction of air blowing (compression) by the blower 36, and the heat transfer tubes 20, 26 of each section 12A, 12B are provided at the lower end thereof. The part is erected while being supported by the base 34. An opening 35 is formed in a portion of the base 36 corresponding to each of the heat transfer tubes 20 and 26, so that a space between the tube main body 21a and the outer cylindrical portion 21c in each of the heat transfer tubes 20 and 26 (hereinafter, referred to as a space). The internal space of the heat transfer tubes 20 and 26) communicates with the inside of the base 34.
[0031]
The inlet-side header 16 and the branch pipe 18 are arranged inside the base 34, and the lower ends of the heat transfer tubes 20 (tube main bodies 21a) belonging to the evaporating section 12A are connected to the branch pipes 18 inside the base. ing. Further, the heat transfer tube 26 belonging to the heating section 12B is connected to the inside of the base via the connecting tube 28 as described above, and further connected to the outlet side header 30 disposed inside the base.
[0032]
In addition, inside the base 34, at a portion corresponding to the evaporating section 12A, a pair of guide plates 38 are arranged side by side in the blowing direction of the blower 36 as shown in FIG. These guide plates 38 are provided so as to be inclined upward from leeward to leeward, thereby deflecting the blast toward the evaporator.
[0033]
Next, the operation and effect of the vaporizer 10 configured as described above will be described.
[0034]
In the vaporizer 10, LNG is guided to the inlet side header 16 through the supply pipe 14, is first introduced into each heat transfer pipe 20 of the evaporator 12 A through each branch pipe 18, and flows (rises) through each heat transfer pipe 20. Heat exchange with the air is performed, thereby gasifying (vaporizing) and taking out as NG. Then, the heat is further guided to the heating section 12B through the transfer pipe 24, and heat exchange with air is performed while sequentially passing through the seven heat transfer pipes 26 belonging to each row of the heating section 12B. After being heated up to the outlet side, it is discharged through the discharge pipe 32 while being collected in the outlet side header 30.
[0035]
Then, while the LNG flows as described above, the blower 36 is driven, whereby outside air (air) is forcibly introduced from the opening 35 into the internal spaces of the heat transfer tubes 20 and 26 through the inside of the base 34. (Indicated by a broken arrow in FIG. 2).
[0036]
When the air is concentrated and introduced into the narrow space around each heat transfer tube in this manner, the ventilation speed of the air around the tube main body is increased, thereby increasing the heat transfer efficiency. In addition, by increasing the heat transfer efficiency in this way, frost formation on the tube body 21a or the radial fins 21b due to heat exchange between LNG or the like and air is suppressed, and the heat transfer area in the heat transfer tubes 20, 26 is reduced. An effectively secured state will be maintained.
[0037]
Therefore, the interval at which the defrosting operation is performed can be extended as compared with a conventional evaporator of this type, and depending on conditions, it is possible to operate continuously without performing the defrosting operation at all, There is an effect that the operation performance of the vaporizer 10 can be significantly improved.
[0038]
In addition, since the heat transfer tubes 20 and 26 are provided with the outer cylindrical portion 21c, the heat transfer tubes 20, 26 are compared with conventional heat transfer tubes of this type, that is, heat transfer tubes having only radial fins around the tube body. Has a large heat transfer area. Therefore, as compared with the conventional vaporizer having the same number of heat transfer tubes, the heat transfer area of the heat transfer tubes 20 and 26 is large, so that heat exchange with LNG or the like can be performed more efficiently.
[0039]
Further, since the guide plate 38 is provided inside the base 34 so that air can be easily introduced into each heat transfer tube 20 of the evaporating section 12A, each of the evaporating section 12A and the heating section 12B is shared through the common base 34. While adopting a rational configuration for introducing air into the heat transfer tubes 20 and 26, there is also an effect that air can be satisfactorily introduced into the internal space of each heat transfer tube 20 on the evaporation unit side where frost is likely to occur. .
[0040]
By the way, even in the conventional vaporizer having a plurality of heat transfer tubes provided with only radial fins around the tube main body, for example, by arranging each heat transfer tube as close as possible, the air ventilation area is reduced, As a result, it is possible to improve the driving performance to some extent by increasing the air ventilation speed and suppressing the occurrence of frost. However, in this case, as a result of arranging the heat transfer tubes close to each other, stress due to heat shrinkage at a joint between each heat transfer tube and a pipe connecting the heat transfer tubes is increased, and the thermal fatigue life is shortened. In this regard, according to the vaporizer 10 described above, the occurrence of frost can be favorably suppressed irrespective of the interval between the heat transfer tubes 20 and 26. Therefore, the heat transfer tubes 20 and 26 are arranged in a spaced apart manner. As a result, while the operating performance is improved, the above-mentioned thermal stress is also reduced.
[0041]
The vaporizer 10 described above is a preferred embodiment of the air-heated liquefied gas vaporizer according to the present invention, and its specific configuration can be appropriately changed without departing from the gist of the present invention. .
[0042]
For example, instead of the heat transfer tubes 20 and 26 having the circular cross section shown in FIG. 4, a heat transfer tube 20 having a polygonal cross section as shown in FIG. 5 can be applied.
[0043]
Further, heat transfer tubes 20 and 26 having a structure in which the outer cylindrical portion 21c and the radial fins 21b are separated from each other can be applied. However, in this case, the heat transfer area of the heat transfer tube 20 is smaller than that of the embodiment (see FIG. 4). Therefore, in order to enhance the heat exchange capacity, a configuration in which the outer cylindrical portion 21c and the radial fins 21b are connected, more preferably, the tube main body 21a, the radial fins 21b, and the outer cylindrical portion 21c are integrally provided as in the above embodiment. It is preferable to use a heat transfer tube 20 having an integral structure.
[0044]
In the above-described embodiment, air is introduced into the internal space of each of the heat transfer tubes 20 and 26 from the lower end and is discharged to the upper end while the air is pressure-fed by driving the blower 36. The blower 36 may be mounted in the opposite direction so as to discharge air, and may be forcibly introduced into the internal spaces of the heat transfer tubes 20 and 26 while sucking air from the upper end thereof. However, in this case, as a result of the cold air having passed through the heat transfer tubes 20 and 26 being discharged through the base 34 and the blower 36, frost formation on the blower 36 and the like may occur. Therefore, in consideration of maintainability and the like, it is more preferable to adopt the configuration of the above-described embodiment in which air is introduced into the heat transfer tubes 20 and 26 by pressure feeding.
[0045]
Further, in the above-described embodiment, the heat transfer tube 20 of the evaporator 12A and the heat transfer tube 26 of the heater 12B have the same structure. For example, the heating unit is less likely to form frost than the evaporator 12A. For 12B, a conventional general heat transfer tube, that is, a heat transfer tube provided with only radial fins around the tube body may be applied.
[0046]
In addition, a control device that can control the air volume of the blower 36 is provided, and the air volume of the heat transfer tubes 20 and 26 is controlled by controlling the air volume of the blower 36 as necessary. You may comprise.
[0047]
In the above embodiment, LNG (liquefied natural gas) is used as the liquefied gas. However, the air-heated vaporizer for liquefied gas of the present invention uses other low-temperature liquefied gas, such as liquid nitrogen or liquid oxygen. The same can be applied to the case of forming.
[0048]
【The invention's effect】
As described above, the present invention is directed to liquefaction in which a liquefied gas is generated by flowing a liquefied gas through a plurality of heat transfer tubes having radial fins extending in the tube axis direction around the tube main body and exchanging heat with air. In the air-heated gas vaporizer for gas, a cylindrical outer cylinder surrounding the heat transfer tube from the outside of the radial fin is provided for each heat transfer tube, and air is forcibly forced into a space between the heat transfer tube and the outer cylinder. By introducing the air, the air is concentrated around the fins of each heat transfer tube, thereby increasing the ventilation speed and increasing the heat transfer efficiency, so that the formation of frost due to the heat exchange between the liquefied gas and the air Can be effectively suppressed. Therefore, the interval at which the defrosting operation is performed can be extended as compared with a conventional evaporator of this type, and depending on the conditions, it is possible to operate continuously without performing the defrosting operation at all, There is an effect that the operation performance of the vaporizer can be significantly improved.
[Brief description of the drawings]
FIG. 1 is a schematic view (front view) showing an air-heated liquefied gas vaporizer according to the present invention.
FIG. 2 is a sectional view showing a specific configuration of a base portion of the liquefied gas air-heated vaporizer.
FIG. 3 is a schematic plan view showing an arrangement of heat transfer tubes in an evaporating section and a heating section.
FIG. 4 is a cross-sectional view showing a configuration of a heat transfer tube applied to a liquefied gas air-heated vaporizer.
FIG. 5 is a sectional view showing another configuration of the heat transfer tube.
[Explanation of symbols]
Reference Signs List 10 Air-heated vaporizer 12A for liquefied gas 12A Evaporator 12B Heater 20, 26 Heat transfer tube 21a Tube main body 21b Radial fin 21c Outer cylinder (outer cylinder)
34 Base (Duct)
36 blower

Claims (7)

For a liquefied gas that has a plurality of heat transfer tubes having radial fins extending in the tube axis direction around a tube main body, and allows a liquefied gas to flow through each of the heat transfer tubes and exchange heat with air to generate a gaseous body. In air-heated vaporizers,
A tubular outer cylinder provided for each heat transfer tube and surrounding the heat transfer tube from outside the radial fins; and a forced flow forcibly introducing air into a space between each heat transfer tube and the outer cylinder. An air-heated vaporizer for liquefied gas, comprising: forming means. The liquefied gas air-heated vaporizer according to claim 1,
An air-heated liquefied gas vaporizer, wherein a radial fin of the heat transfer tube is connected to the outer cylinder. The liquefied gas air-heated vaporizer according to claim 2,
The air-heated vaporizer for liquefied gas, wherein the heat transfer tube has an integral structure in which an inner peripheral surface of the outer cylindrical body is joined to a tip of the radial fin. The liquefied gas air-heated vaporizer according to claim 2,
The duct having a heat exchanger and a duct as the forced flow forming means, wherein the heat transfer tube and the outer cylinder are common in a state where the space between the heat exchanger and the outer cylinder communicates with the inside of the duct. An air-heated vaporizer for liquefied gas characterized by being assembled to The liquefied gas air-heated vaporizer according to claim 4,
An air-heated vaporizer for liquefied gas, wherein the forced flow forming means is configured to pressurize air into the duct by the blower. The liquefied gas air-heated vaporizer according to claim 4 or 5,
It has a plurality of the heat transfer tubes connected in parallel, has an evaporator that gasifies the liquefied gas by distributing and introducing the liquefied gas to each heat transfer tube, and a plurality of the heat transfer tubes connected in series. A heating unit that raises the temperature of a gaseous body derived from the evaporating unit, wherein each of the heat transfer tubes and the outer cylindrical body of the evaporating unit and the heating unit are assembled to the common duct. Air-heated vaporizer for liquefied gas. The air-heated vaporizer for liquefied gas according to claim 6,
The evaporating section and the heating section are provided in order from the upstream side in the direction of air pressure feeding by the blower, and a guide member for guiding air to a portion corresponding to the evaporating section is provided in the duct. Air-heated vaporizer for liquefied gas.

Images