JPH11294694A - Forced-circulation-type air hot-type liquefied gas evaporator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently vaporize liquefied gas without generating white fuming, and eliminate requirement of any thawing work by water spray. SOLUTION: This forced-circulation-type air-hot-type liquefied gas vaporizing device 10 is a liquefied gas vaporizing system which vaporizes LNG flowing inside a vaporization tube 11 using air flowing outside the vaporization tube 11, a housing 12 for sealing the vaporization tube 11 from outside, a temperature rising device 14 which is connected with this housing 12 through an air circulation piping 13 and rises temperature of air flowing in the air circulation piping 13, and a blasting fan 15 for circulating air between this temperature rising device 14 and the housing 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquefied natural gas (L)
NG), liquefied petroleum gas (LPG), liquid nitrogen, liquid oxygen, and the like.

[0002]

2. Description of the Related Art As a conventional liquefied gas vaporization system, for example, a ventilation type air temperature type using air as a heat source and a hot water type using hot water as a heat source are known, such as LNG, LPG, liquid nitrogen, and liquid oxygen. Is installed in liquefied gas satellite facilities. Therefore, a ventilated air-heated liquefied gas vaporization system and a hot-water liquefied gas vaporization system installed in the LNG satellite facility will be described as examples. The ventilated air-heated liquefied gas vaporization system uses natural ventilation (convection of air)
This is a method in which forced air is blown toward the NG finned evaporation tube, and the LNG flowing through the finned evaporation tube is evaporated using the air as a heat source. In addition, the hot water liquefied gas vaporization system circulates hot water in a hot water tank in which, for example, an LNG evaporating tube is immersed, and uses the circulated hot water as a heat source to flow through the evaporating tube.
This is a method of vaporizing NG. The hot water liquefied gas vaporization system has a relatively low facility cost, but requires a heat source to produce hot water, and thus has a high running cost.

However, as shown in FIG. 5, for example, a ventilation type air-heated liquefied gas vaporization system includes an LNG finned evaporator tube 1, a housing 2 surrounding the evaporator tube, and a ceiling 2 of the housing 2. A fan 3 is provided, and an upward flow of air is generated by the fan 3 as shown by an arrow in the figure, and the heat of the air and the LNG in the evaporation tube 1 while the air passes through the finned evaporation tube 1. LNG is vaporized by the exchange, and natural gas (NG) is obtained. This ventilation type air temperature liquefied gas vaporization system is widely used because its running cost is low.

However, in the above-mentioned ventilation type air-heated liquefied gas vaporization system, during operation, the water vapor contained in the air is frosted and frozen on the finned evaporating tube 1 and further grows. The heat transfer efficiency of the tube 1 gradually decreases, and the gap between the fins of the evaporator tube 1 with fins is filled with icing, and the heat transfer area is drastically reduced. Therefore, a spare evaporator is conventionally prepared, and when the heat transfer efficiency is reduced due to icing of the evaporator tube 1, the LNG supply line is switched to the spare unit at that time, and the spare unit is attached during operation. The ice is evaporated on the evaporating tube 1 to be thawed, and the system waits until the next switching point of the LNG supply line, and alternately uses two or more spare units.

[0005]

However, in the case of the conventional air-heated liquefied gas vaporization system, not only a spare vaporizer is required as described above, but also a deicing facility (for example, a water spray facility, Drains, etc.), resulting in an increase in equipment costs. Further, there is a problem that the temperature around the vaporizer reaches a temperature equal to or lower than the dew point and white smoke is generated, and the white smoke lowers the visibility near the vaporizer. In order to suppress icing and to prevent white smoke, a method of forcibly ventilating dehumidified dry air having a very low dew point can be considered, but the use of such dry air increases running costs. In addition, Japanese Patent Application Laid-Open No. Hei 9-1655
No. 88 proposes a device for preventing white smoke from a liquefied gas evaporator. However, in this technology, there is no difference in that air passes through the air, and it is difficult to prevent icing on the evaporating tube. There were challenges.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can efficiently vaporize a liquefied gas without generating white smoke. Further, there is no need to perform a de-icing operation by spraying water. It is an object of the present invention to provide a forced circulation air-heated liquefied gas vaporizer that does not require a spare vaporizer and can reduce running costs.

[0007]

According to a first aspect of the present invention, there is provided a forced-circulation type air-heated liquefied gas vaporizer for converting a liquefied gas flowing inside an evaporating tube by using air flowing outside the evaporating tube. In a forced circulation type air temperature type liquefied gas vaporizer for vaporizing a liquefied gas, a housing surrounding at least the upstream side of the evaporating pipe from the outside, and connected to the housing via an air circulation path and in the air circulation path And a blower for circulating air between the temperature raising means and the housing.

Further, in the forced circulation type air-heated liquefied gas vaporizer according to a second aspect of the present invention, the liquefied gas flowing inside the evaporating tube is vaporized by utilizing the air flowing outside the evaporating tube. In a forced circulation type air-heated liquefied gas vaporizer, a housing enclosing the evaporating tube from the outside and forming a space at least on the downstream side and at both upper and lower sides thereof, and within the housing, the evaporating tube is positioned on the downstream side. A partition plate for partitioning from the side space, a blower for circulating the air in the housing between the side space and the evaporating pipe partitioned by the partition plate, and heating the air circulating through the blower. And a temperature raising means.

Further, in the forced circulation type air-heated liquefied gas vaporizer according to a third aspect of the present invention, the liquefied gas flowing inside the evaporating tube is converted into the liquefied gas using air flowing outside the evaporating tube. In a forced circulation type air-heated liquefied gas vaporizer for evaporating water, a housing surrounding the evaporating tube from the outside and forming spaces on both upper and lower sides thereof, and within the housing, the evaporating tube is connected to the evaporating tube on the upstream side and the evaporating tube on the downstream side. A partition plate for partitioning the evaporator tube, a blower for circulating the air in the housing between the upstream side and the downstream side of the partition plate, and a temperature raising means for raising the temperature of the air circulating through the blower. It is characterized by having.

In a fourth aspect of the present invention, there is provided a forced circulation air-heated liquefied gas vaporizer according to the first aspect of the invention. An air heater for raising the temperature of the air circulating in the evaporator tube, a pump for circulating the heat medium through the heat medium circulation path to the air heater, and raising the temperature of the heat medium circulated by the pump And a heat medium heater.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in FIGS. FIG. 1 is a flowchart showing the whole of a forced circulation type air-heated liquefied gas vaporizer (hereinafter simply referred to as “air-heated vaporization system”) according to an embodiment of the present invention, and FIG. FIGS. 3 and 4 showing another embodiment, and FIGS. 3 and 4 are diagrams corresponding to FIG. 1 showing still another embodiment of the present invention.

The air temperature type vaporization system 10 according to the present embodiment comprises:
As shown in FIG. 1, a finned evaporating tube 11, a housing 12 surrounding the entire evaporating tube 11,
2 through an air circulation pipe 13 and a temperature raising device 14 for raising the temperature of air flowing through the air circulation pipe 13
And a blower fan 15 for circulating air between the temperature raising device 14 and the housing 12. One end of the air circulation pipe 13 is connected to an upper part of the housing 12, and the other end is connected to a lower part of the housing 12. Therefore, the air circulated by the blower fan 15 flows from the ceiling side of the housing 12 into the interior thereof, passes through the interior of the housing 12 through the entire evaporating pipe 11 in a downward flow, and during this time, LNG in the evaporating pipe 11 is vaporized. The cooling air flowing out of the housing 12 passes through the air circulation pipe 13 to the heating device 14.
And is heated in the temperature raising device 14.

As shown in FIG. 1, the temperature raising device 14
An air heater 141 composed of a heat exchanger disposed in the air circulation pipe 13 and a heat transfer tube 141A of the air heater 141
Heat medium circulation pipe 142 connected to the heat medium circulation pipe 142, a pump 143 and a heat medium heater (for example, a brine heater) 14 sequentially arranged from the upstream side to the downstream side in the heat medium circulation pipe 142.
4. The heat recovery unit 145 and the auxiliary heater 146 are provided, and while the brine as the heat medium circulates through the heat medium circulation pipe 142, the brine exchanges heat with the circulating air in the air circulation pipe 13 in the air heater 141. , The brine heater 144, the heat recovery unit 145, and the auxiliary heater 1
It is heated by 46. The brine heater 144 includes a finned heat transfer tube 144A and a fan 14.
4B, and the air flowing from the fan 144B is used to heat the brine flowing in the finned heat transfer tube 144A. Further, the heat recovery unit 145 recovers, for example, residual heat and waste heat generated in other equipment, and heats the brine using the recovered heat. The auxiliary heater 146 is used when the brine cannot be heated to a predetermined temperature by the brine heater 144 and the heat recovery device 145. In particular, in the severe cold season, both the heat recovery device 145 and the auxiliary heater 146 are used to secure the brine. To a predetermined temperature, and the air heater 141
Ensure that it performs its function. Therefore, when the outside air temperature is relatively high, only the brine heater 144 sufficiently performs its function.

Next, the operation will be described. For example,-
LNG at 160 ° C. flows into the finned evaporator tube 11 at a predetermined flow rate, and air at −5 ° C. to 25 ° C. flows into the housing 12 at a predetermined flow rate. Thereby, the evaporating tube 11
LNG flowing through the inside is heated and vaporized by air flowing in the housing 12 in a downward flow, and is, for example, −15 ° C. to 15 ° C.
It flows out of the evaporating tube 11 as NG whose temperature has been raised to ° C. On the other hand, the air in the housing 12 is
It is cooled to 25 ° C. to 5 ° C. and flows out of the housing 12 to the air circulation pipe 13. This cooling air is supplied to the air circulation pipe 1
3 and is heated by the air heater 141 to be heated to the original temperature (−5 ° C. to 25 ° C.), flows into the housing 12, and vaporizes LNG again as described above. Let it. Since the air flowing through the air circulation pipe 13 contains water vapor, some icing is observed in the evaporating pipe 11 in the initial stage of operation, but the icing gradually dehumidifies the circulating air and lowers the dew point. However, subsequent icing is eliminated, and LNG can be vaporized with high heat transfer efficiency.

On the other hand, the heating device 14 has an air heater 141.
Low-temperature air at -25 ° C to 5 ° C flows into the shell side, and brine at 0 ° C to 30 ° C flows into the heat transfer tube 141A via the heat medium circulation pipe 142. As a result, the low-temperature air flowing on the shell side is heated by the brine flowing in the heat transfer tube 141A and the temperature thereof rises.
The temperature rises to 5 ° C. to 25 ° C. and flows out of the air heater 141. The brine in the heat transfer tube 141A is cooled by low-temperature air and is cooled to, for example, −5 ° C. to 25 ° C.
It flows out from 41 to the heat medium circulation pipe 142. The brine is supplied to the brine heater 14 via a heat medium circulation pipe 142.
4 while the brine passes through the finned heat transfer tube 144A, the brine is heated by the forced draft from the fan 144B and rises to the original temperature (0 ° C. to 30 ° C.). It flows into the air heater 141 and again heats the low-temperature air as described above. Further, when the outside air temperature decreases such as in a severe cold season, the heating of the brine by the air in the brine heater 144 becomes insufficient.
45, in some cases, using the auxiliary heater 146 to heat the brine to a predetermined temperature.

As described above, according to the present embodiment,
Housing 12 surrounding finned evaporation tube 11 from outside
A heating device 14 connected to the housing 12 via an air circulation pipe 13 and raising the temperature of the air flowing through the air circulation pipe 13, and air between the heating device 14 and the housing 12. A circulating blower fan 15 is provided to circulate a certain amount of air in the closed system to vaporize LNG, so that the water vapor contained in a certain amount of air only accumulates on the evaporating pipe 11. Already, evaporation tube 11
LNG can be efficiently vaporized while maintaining a high heat transfer efficiency throughout, and white smoke in the vicinity of the housing 12 can be prevented. Moreover, in the present embodiment, since there is no need to perform the defrosting operation by watering, a spare evaporating tube and deicing equipment are not required, and the system can be downsized. In addition, since outside air, waste heat, and the like are basically used as a heating source for circulating air for vaporizing LNG, running costs can be reduced.

FIG. 2 is a view showing another embodiment of the air-heated vaporization system of the present invention. This air-heated vaporization system 10
FIG. 1A is a view similar to FIG. 1 except that an upstream half of a finned evaporation tube 11 is surrounded by a housing 12A as shown in FIG.
It is configured according to the following. For this reason, in the present embodiment, the same parts as those of the air-temperature type vaporization system 10 shown in FIG. 1 are denoted by the same reference numerals in FIG. 2, and the description thereof will be omitted. In the present embodiment, the upstream half of the evaporating tube 11 is surrounded by the housing 12A, and the evaporating tube 11 is surrounded by the housing 12A.
A certain amount of air is circulated in A to perform dehumidification. Further, since the LNG is vaporized on the downstream side of the evaporating tube 11 and the amount of icing and the amount of white smoke generated are significantly smaller than those on the upstream side, the downstream half of the evaporating tube 11 is exposed in the present embodiment, The downstream half of the evaporating tube 11 is heated by forced ventilation of the outside air.

An air circulation pipe 13 is connected to the housing 12A in the same manner as in the above embodiment, and air is blown by the blower fan 15 through the air circulation pipe 13 and the air heater 141 of the temperature raising device 14. Circulating air, the upstream half of the evaporating tube 11 is heated by the circulating air, and the low-temperature air from the housing 12A is supplied to the air heater 1.
The circulating air is heated to the original temperature by heating with 41. A blower fan (not shown) is provided downstream of the evaporator tube 11, and the blower fan blows air in a downward flow as shown by the arrow in the figure, heats the evaporator tube 11 with outside air, and removes LNG. It promotes vaporization.

Therefore, also in this embodiment, the air circulation pipe 13
The air inside flows into the housing 12A at −5 ° C. to 25 ° C. and flows out of the housing 12A at −25 ° C. to 5 ° C., while the LNG in the evaporating tube 11 is NG at −15 ° C. to 15 ° C.
And flows out of the evaporating tube 11. The air heater 141 heats the air at −25 ° C. to 5 ° C. cooled in the housing 12A to the original temperature (−5 ° C. to 25 ° C.).

As described above, according to the present embodiment,
By reducing the amount of air circulation, the size of the housing 12A can be reduced, and the operation and effect according to the above embodiment can be expected.

FIG. 3 is a diagram showing still another embodiment of the air-heated vaporization system of the present invention. As shown in the drawing, the air-heated vaporization system 10B has a finned evaporator tube 11 surrounded by a housing 12B from the outside, and a blower fan 15B and an air heater 141 are provided in the housing 12B. . In the housing 12B, a space is formed on the downstream side of the evaporator tube 11, and an upper space and a lower space are formed on both upper and lower sides of the evaporator tube 11, respectively. The partition plate 1 is provided inside the housing 12B.
The space 6 separates the side of the evaporating tube 11 from its side space. A blower fan 15B is provided in the side space, and air in the housing 12B is blown by the blower fan 15B, and the air passes through the side space by an upward flow as indicated by an arrow in FIG. From the space, it passes through the evaporating tube 11 in a descending flow, and returns and circulates through the lower space. An air heater 141 is disposed above the evaporator tube 11 with a gap between the evaporator tube 11 and the evaporator tube 11. The air heater 141 heats the air, and the heated air descends through the entire evaporator tube 11. LNG in the evaporating tube 11 is vaporized while passing through the flow. In this embodiment, the same parts as those of the air temperature type vaporization system 10 shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

Therefore, in this embodiment, the air heater 141 is used.
The circulating air at −5 ° C. to 25 ° C. heated in the evaporator 11 passes through the entirety of the evaporating tube 11 in a downward flow.
Cool down to ° C. After that, this cooling air is
Through the side space and the air heater 141, the original temperature (−
(5 ° C. to 25 ° C.) and the evaporating pipe 11 is circulated in a downward flow.
At this time, LNG flows into the evaporating tube 11 at −160 ° C.
It is vaporized in the evaporating tube 11 and becomes NG at −15 ° C. to 15 ° C. and flows out from the evaporating tube 11. On the other hand, the brine heater 14
The brine of 0 ° C. to 30 ° C. heated by 4 or the like passes through the air heater 141, and is -5 ° C. to 2 ° C. in the air heater 141.
Cooled to 5 ° C., returned to the original temperature (0 ° C. to 30 ° C.) again through the brine heater 144, etc.
42.

As described above, according to the present embodiment,
The evaporating pipe 11 can be heated by circulating a certain amount of air in the housing 12B, and the air circulation pipe can be omitted to reduce the size of the entire apparatus. Can be expected

FIG. 4 is a view showing still another embodiment of the air-heated vaporization system of the present invention. As shown in the figure, the air-heated vaporization system 10C has a finned evaporator tube 11 surrounded by a housing 12C from the outside, and a blower fan 15C and an air heater 141 disposed in the housing 12B. . An upper space and a lower space are respectively formed on the upper and lower sides of the evaporating tube 11 in the housing 12C, and the evaporating tube 11 is further divided into an upstream half and a downstream half by a partition plate 17 in the housing 12C. A blower fan 15C is provided in a lower space on the upstream side of the evaporator tube 11, and the blower fan 15C allows air to circulate in the housing 12C as indicated by an arrow in the figure. Therefore, the air passes through the upstream half of the evaporating tube 11 in ascending flow, and passes through the upper space through the evaporating tube 11.
After passing through the downstream half of the as a descending flow, it returns and circulates. An air heater 141 is disposed above the evaporator tube 11 with a gap between the evaporator tube 11 and the evaporator tube 11. The air heater 141 heats the circulating air. The air passing through the lower half of the evaporating tube 11 in the descending flow passes through the upper half of the evaporating tube 11 in the ascending flow, thereby effectively vaporizing the LNG in the evaporating tube 11. In this embodiment, the same parts as those of the air temperature type vaporization system 10 shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

Therefore, in this embodiment, the air heater 141 is used.
The circulating air at −5 ° C. to 25 ° C. heated in the downstream direction passes through the downstream half of the evaporating tube 11 in a downward flow, and
Cool to 3 ° C to 3 ° C. Thereafter, the cooling air passes through the lower space, passes through the upstream half of the evaporating tube 11 by ascending flow, is further cooled to −25 ° C. to 5 ° C., and then returns to the original temperature via the air heater 141 ( (−5 ° C. to 25 ° C.). At this time, the air passing through the upstream half of the evaporating tube 11 is cooled on the downstream side. However, since the upstream half of the evaporating tube 11 is extremely low temperature, the temperature difference from the cooling air is still very large. The upstream half of the evaporating tube 11 can be effectively heated, and the vaporization of LNG can be promoted.
LNG in the tube becomes NG at -15 ° C to 15 ° C, and the evaporating tube 1
Flow out of 1. On the other hand, the brine of 0 ° C. to 30 ° C. heated by the brine heater 144 or the like passes through the air heater 141, is cooled to −5 ° C. to 25 ° C. in the air heater 141, and again passes through the brine heater 144 or the like. It returns to the original temperature (0 ° C. to 30 ° C.) and circulates through the heat medium circulation pipe 142.

As described above, according to the present embodiment,
It is possible to further promote downsizing as compared with the embodiment shown in FIG. 3, and to achieve the same effects as those of the above embodiments.

It should be noted that the present invention is not limited to the above-described embodiments. The present invention includes any device that circulates a fixed amount of air in a closed circulation path to vaporize LNG in the evaporation tube. Is done.

[0028]

According to the first to fourth aspects of the present invention, the liquefied gas can be efficiently vaporized without generating white smoke, and the de-icing operation by spraying water is performed. It is possible to provide a forced circulation air-temperature liquefied gas vaporizer that does not require a spare vaporizer and can reduce running costs.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an entire air-heated vaporization system according to an embodiment of the present invention.

FIG. 2 is a view corresponding to FIG. 1 showing another embodiment of the present invention.

FIG. 3 is a view corresponding to FIG. 1, showing still another embodiment of the present invention.

FIG. 4 is a view corresponding to FIG. 1, showing still another embodiment of the present invention.

FIG. 5 is a configuration diagram showing an example of a conventional air-heated vaporization system.

[Explanation of symbols]

10, 10A, 10B, 10C Air-temperature vaporization system 11 Evaporation pipe 12, 12A, 12B, 12C Housing 13 Air circulation pipe (air circulation path) 14 Heating device (heating means) 15, 15B, 15C Blow fan (blower) ) 16, 17 Partition plate 141 Air heater 142 Heat medium circulation pipe 143 Pump 144 Brine heater

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shunji Hayashi 3-3-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Kakoki Machinery Co., Ltd. (72) Inventor Takeshi Nozawa 3-3-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa No. Mitsubishi Kaiko Co., Ltd. (72) Inventor Masashi Miura 3-3-1 Minatomirai, Nishi-ku, Yokohama City, Kanagawa Prefecture Mitsubishi Kako Machine Co., Ltd.

Claims (4)

[Claims] 1. A forced circulation type air-heated liquefied gas vaporizer for vaporizing a liquefied gas flowing inside an evaporating tube using air flowing outside the evaporating tube, wherein at least an upstream side of the evaporating tube is provided. A housing which is enclosed from the outside, a heating means connected to the housing via an air circulation path and which raises the temperature of the air flowing through the air circulation path, and air between the heating means and the housing. A forced circulation air-heated liquefied gas vaporizer, comprising: a circulating blower. 2. A forced circulation air-heated liquefied gas vaporizer for vaporizing a liquefied gas flowing inside an evaporating tube by using air flowing outside the evaporating tube, wherein the evaporating tube is surrounded from outside. A housing that forms a space at least on the downstream side and on both upper and lower sides thereof, a partition plate that partitions the evaporating tube from the downstream side space in the housing, and the side space that is partitioned by the partition plate. A forced circulation type air-heated liquefied gas, comprising: a blower for circulating the air in the housing between the evaporator tube and a heating means for raising the temperature of the air circulated through the blower. Vaporizer. 3. A forced circulation type air-heated liquefied gas vaporizer for vaporizing a liquefied gas flowing inside an evaporating tube using air flowing outside the evaporating tube, wherein the evaporating tube is externally connected to the evaporating tube. A housing that surrounds and forms a space on both upper and lower sides thereof, a partition plate that partitions the evaporating tube into an upstream evaporating tube and a downstream evaporating tube in the housing, and a partition plate between the upstream side and the downstream side of the partition plate. A forced circulation air-temperature liquefied gas vaporizer, comprising: a blower for circulating the air in the housing; and a temperature raising means for raising the temperature of the air circulated through the blower. 4. An air heater for raising the temperature of air circulating in the evaporator tube, a pump for circulating a heat medium through a heat medium circulation path to the air heater, The forced circulation type air-heated liquefied gas vaporizer according to any one of claims 1 to 3, further comprising a heat medium heater configured to raise the temperature of the heat medium circulated by a pump.