JP2016027272A - Liquefied gas evaporation device and liquefied gas evaporation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquefied gas evaporation device which uses an intermediate medium and effectively utilizes condensed water occurring on a surface of a heat transfer pipe, in which the intermediate medium flows, to effectively reduce the electric power consumption.SOLUTION: A liquefied gas evaporation device is provided with: an intermediate medium heater 10 which evaporates an intermediate medium LP flowing in a heat transfer pipe 11 by heat exchange with a heating gas; a liquefied gas evaporator 20 which evaporates a liquefied gas LNG by heat exchange with the intermediate medium GP evaporated by the intermediate medium heater 10 to generate a flash gas NG; and a gas pipeline 50 in which the flash gas NG generated by the liquefied gas evaporator 20 flows. Condensed water occurring on a surface of the heat transfer pipe 11 is heated by heat exchange with atmospheric air in a state where the condensed water is stored in a storage tank 60 disposed at a position lower than the heat transfer pipe 11 and then is flowed to the gas pipeline 50 located at a positioned lower than the storage tank 60 to heat the flash gas NG in the gas pipeline 50.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquefied gas vaporizer and a liquefied gas vaporization system for vaporizing a liquefied gas by heat exchange with an intermediate medium.

  As a liquefied gas vaporizer that vaporizes liquefied gas by heat exchange with an intermediate medium, for example, there is one described in Patent Document 1. In this liquefied gas vaporizer, the intermediate medium is circulated between the intermediate medium evaporation section and the liquefied gas vaporization section, and the intermediate medium vaporized in the intermediate medium evaporation section is condensed in the liquefied gas vaporization section, thereby reducing the temperature. The liquefied gas is vaporized to generate the vaporized gas. According to this configuration, since the liquefied gas is vaporized using the condensation latent heat of the intermediate medium, the amount of circulation of the intermediate medium can be reduced according to the enthalpy ratio of latent heat / sensible heat. Yes.

JP 2013-32836 A

  By the way, in the liquefied gas vaporizer described above, the intermediate medium in the heat transfer tube is vaporized by circulating the atmosphere around the heat transfer tube of the intermediate medium evaporation section. At this time, water vapor contained in the atmosphere is transferred. Condensed water is generated by condensation on the surface of the heat tube. The condensed water generated in this way is generally discarded without being particularly used, and a method for effectively utilizing the condensed water has been demanded.

  On the other hand, the vaporized gas vaporized in the liquefied gas vaporization unit is generally heated to a predetermined target temperature by a heater, but additional power is required to operate the heater. Become. Therefore, there is a demand for reducing the power consumption in the liquefied gas vaporizer by reducing the load on the heater as much as possible and eliminating the heater in some cases.

  In view of such a current situation, the present invention effectively uses the condensed water generated on the surface of the heat transfer tube through which the intermediate medium flows in the liquefied gas vaporization apparatus and the liquefied gas vaporization system using the intermediate medium, thereby reducing power consumption. The purpose is to reduce it.

  In order to achieve the above object, a liquefied gas vaporizer according to the present invention includes an intermediate medium heater for heating an intermediate medium flowing in a heat transfer tube by heat exchange with a heating gas, and the intermediate medium heating A liquefied gas evaporator that vaporizes a liquefied gas to generate a vaporized gas by heat exchange with the intermediate medium that has been heated in a vessel; a gas pipe through which the vaporized gas generated by the liquefied gas evaporator flows; The heating gas contains water vapor, and the surface temperature of the heat transfer tube is lower than the dew point of the heating gas, so that condensed water is generated on the surface of the heat transfer tube, The condensed water is heated by heat exchange with the atmosphere in a state where it is stored in a storage part of a storage tank disposed at a position lower than the heat transfer pipe, and then to the gas pipe at a position lower than the storage tank. By letting it flow down, inside the gas pipe Characterized by heating the vaporized gas.

  In the present invention, the condensed water generated on the surface of the heat transfer tube of the intermediate medium heater is heated by heat exchange with the atmosphere while being stored in the storage portion of the storage tank. And the vaporized gas in gas piping is heated because the heated condensed water flows down to gas piping. Thus, by using the condensed water, the electric power necessary for heating the vaporized gas can be reduced. In addition, since the heat transfer tubes, the storage tanks, and the gas pipes are arranged in this order from the highest to the lowest, the condensed water can flow down only by gravity, and no additional power is required. In addition, since the heat of the atmosphere is used to heat the condensed water, no additional power is required for this. That is, according to the present invention, it is possible to effectively use the condensed water generated on the surface of the heat transfer tube and effectively reduce the power consumption.

It is a schematic diagram which shows the whole structure of a liquefied gas vaporizer. It is a perspective view which shows a storage tank in detail. It is a top view which shows the flow of the condensed water in a storage tank. It is a top view which shows arrangement | positioning of a 1st storage tank and a gutter member. It is a perspective view which shows a part of collar member in detail. It is sectional drawing for demonstrating suitable arrangement | positioning of a collar member. It is a graph which shows a temperature change when water of 0 degreeC is heated by air | atmosphere by heat exchange. It is a graph which shows the relationship between the residence time required in order to make 0 degreeC water into the same temperature as external temperature by heat exchange with air | atmosphere, and an average liquid film thickness. It is a top view which shows the modification of a storage tank. It is a top view which shows the modification of a storage tank. It is a top view which shows the modification of a storage tank. It is a top view which shows the modification of a storage tank. It is a schematic diagram which shows the whole structure of a liquefied gas vaporization system. It is a perspective view which shows a part of condensation part. It is a graph which shows the relationship between a circulating piping diameter and a pressure loss. It is a graph which shows the relationship between ammonia flow volume, a pressure loss, or the number of passes. It is a graph which shows the relationship between ammonia flow volume, a pressure loss, or exchange heat quantity. It is a graph which shows the relationship between ammonia flow volume, a pressure loss, or exchange heat quantity.

  An embodiment of a liquefied gas vaporizer according to the present invention will be described with reference to the drawings. In this embodiment, propane is used as an intermediate medium, and liquefied natural gas (LNG) is vaporized to generate natural gas (NG: Natural Gas). The target liquefied gas is not limited to this. For example, a medium that evaporates at room temperature and does not solidify at a normal temperature (low temperature) (a medium having a boiling point lower than the atmospheric temperature), such as propylene and alternative chlorofluorocarbon, may be used as the intermediate medium, Antifreeze may be used. The liquefied gas to be vaporized may be a low-temperature liquefied gas such as ethylene, liquefied oxygen, or liquefied nitrogen.

(Overall configuration of liquefied gas vaporizer)
In FIG. 1, the whole structure of the liquefied gas vaporization apparatus 1 concerning this embodiment is shown. The liquefied gas vaporizer 1 vaporizes the liquefied natural gas LNG by the intermediate medium heater 10 for vaporizing the liquid propane LP into the gaseous propane GP and the condensation heat when the gaseous propane GP condenses to produce the natural gas NG. The liquefied gas evaporator 20 to be generated and the vaporized gas heater 30 that is arranged on the downstream side of the liquefied gas evaporator 20 and warms the natural gas NG are included.

  A circulation pipe 40 is disposed between the intermediate medium heater 10 and the liquefied gas evaporator 20. By operating a pump 41 provided in the circulation pipe 40, propane as an intermediate medium flows through the circulation pipe 40. In addition, a gas pipe 50 is provided from the supply source (not shown) of the liquefied natural gas LNG to the gas tank (not shown) outside the apparatus via the liquefied gas evaporator 20 and the vaporized gas heater 30. Has been. The natural gas NG produced by the liquefied gas evaporator 20 flows through the gas pipe 50 and finally reaches the gas tank.

  With the above configuration, the low-temperature liquefied natural gas LNG supplied to the gas pipe 50 is vaporized by the liquefied gas evaporator 20 to become natural gas NG, and then heated by the vaporized gas heater 30. . Further, in the liquefied gas vaporizer 1, not only the vaporized gas heater 30 but also the natural gas NG is heated by using condensed water generated in the intermediate medium heater 10, whereby the vaporized gas heater 30 is obtained. The power consumption is reduced. This point will be described in detail later. In the following description, the temperature of the atmosphere is 25 ° C. as an example.

(Intermediate medium heater)
The intermediate medium heater 10 includes a heat transfer tube 11 that constitutes a part of the circulation pipe 40, a fan 12 disposed above the heat transfer tube 11, and a motor 13 that rotationally drives the fan 12. The liquid propane LP at 0 ° C. introduced into the heat transfer tube 11 is vaporized by heat exchange with the atmosphere (heating gas) taken in from the outside by the rotation of the fan 12 to become a gas propane GP at 0 ° C. This heat exchange reduces the temperature of the atmosphere from 25 ° C. to 20 ° C. In order to increase the efficiency of heat exchange, the heat transfer tubes 11 are generally arranged in a meandering manner, or fins are provided on the heat transfer tubes 11 (the same applies to the heat transfer tubes 22 and 31 below).

(Liquefied gas evaporator)
The liquefied gas evaporator 20 includes a heat exchange chamber 21 to which gas propane GP is supplied from the circulation pipe 40, a part of the gas pipe 50, a heat transfer pipe 22 disposed in the heat exchange chamber 21, and a heat exchange chamber. 21 and a liquid storage portion 23 formed below 21. Heat exchange is performed between the liquefied natural gas LNG of −160 ° C. introduced into the heat transfer tube 22 and the gas propane GP of 0 ° C. supplied to the heat exchange chamber 21, so that the liquefied natural gas in the heat transfer tube 22 is obtained. The gas LNG is vaporized to generate a natural gas NG of −5 ° C., the gas propane GP is condensed, and the liquid propane LP of 0 ° C. is stored in the liquid storage unit 23.

(Vaporized gas heater)
The vaporized gas warmer 30 includes a heat transfer pipe 31 that constitutes a part of the gas pipe 50, a fan 32 disposed above the heat transfer pipe 31, and a motor 33 that rotationally drives the fan 32. The natural gas NG at −4 ° C. introduced into the heat transfer tube 31 is heated to 4.5 ° C. by heat exchange with the atmosphere taken from the outside by the rotation of the fan 32. This heat exchange reduces the temperature of the atmosphere from 25 ° C. to 20 ° C.

(Storage tank)
As described above, since the liquid propane LP or gas propane GP at 0 ° C. is circulating in the heat transfer tube 11 of the intermediate medium heater 10, the surface temperature of the heat transfer tube 11 is close to 0 ° C. As a result, the surface temperature of the heat transfer tube 11 becomes lower than the dew point of the atmosphere, and water vapor in the air is condensed on the surface of the heat transfer tube 11 to generate condensed water. In the liquefied gas vaporizer 1, three storage tanks 60A, 60B, and 60C are provided to heat the natural gas NG in the gas pipe 50 using the condensed water. In addition, in FIG. 1, the flow of condensed water is typically shown by the block arrow.

  Specifically, the first storage tank 60A is disposed below the heat transfer tube 11 of the intermediate medium heater 10, and the condensed water generated on the surface of the heat transfer tube 11 is collected by the first storage tank 60A. Then, the condensed water stored in the first storage tank 60A is heated to 15 ° C. by heat exchange with the atmosphere, and the heated condensed water is located below the first storage tank 60A. It is made to flow down to 50 1st heating parts 50a. By doing so, the natural gas NG can be raised from −5 ° C. to −4.5 ° C. in the first heating unit 50a. At this time, the temperature of the condensed water decreases from 15 ° C. to 10 ° C.

  Moreover, the 2nd storage tank 60B is arrange | positioned under the 1st heating part 50a, and the condensed water dripped from the 1st heating part 50a is again collect | recovered by the 2nd storage tank 60B. And the condensed water stored in the 2nd storage tank 60B is again heated to 15 degreeC by heat exchange with air | atmosphere, and the gas which is located below the 2nd storage tank 60B is heated. It flows down to the 2nd heating part 50b of the piping 50. FIG. In this way, the natural gas NG can be raised from −4.5 ° C. to −4 ° C. in the second heating unit 50b. At this time, the temperature of the condensed water decreases from 15 ° C. to 10 ° C.

  Furthermore, another second storage tank 60C is disposed below the second heating unit 50b, and the condensed water dripped from the second heating unit 50b is recovered again in the second storage tank 60C. Then, the condensed water stored in the second storage tank 60C is heated again to 15 ° C. by heat exchange with the atmosphere, and the heated condensed water is positioned below the second storage tank 60C. It flows down to the 3rd heating part 50c of the piping 50. FIG. Thus, the natural gas NG can be raised from 4.5 ° C. to 5 ° C. in the third heating unit 50c. At this time, the temperature of the condensed water decreases from 15 ° C. to 10 ° C.

  As described above, the condensed water is collected in the storage tanks 60A, 60B, and 60C, heated by heat exchange with the atmosphere, and allowed to flow down to the gas pipe 50, whereby the first heating unit 50a and the second heating unit are heated. The natural gas NG can be raised by 0.5 ° C. at each of the warming part 50b and the third warming part 50c. Therefore, in raising the natural gas NG to the target temperature (here, 5 ° C.), the load of the vaporized gas heater 30 can be reduced by 1.5 ° C. As a result, the consumption in the vaporized gas heater 30 is reduced. It becomes possible to reduce electric power.

  The first storage tank 60 </ b> A collects the condensed water generated on the surface of the heat transfer tube 11 before flowing down to the gas pipe 50, while the second storage tanks 60 </ b> B and 60 </ b> C flow down to the gas pipe 50. They differ in that the condensed water is recovered again. However, there is no particular difference between the two in terms of collecting, storing, and heating the condensed water. Therefore, in the following description, the first storage tank 60A and the second storage tanks 60B and 60C are simply referred to as “storage tank 60” unless otherwise distinguished.

(Specific configuration of storage tank)
Next, a specific configuration of the storage tank 60 will be described. FIG. 2A is a perspective view of the storage tank 60, and FIG. 2B is a plan view of the storage tank 60. In FIG. 2B, the flow of condensed water is indicated by arrows.

  The storage tank 60 includes a storage unit 61 that stores condensed water, and a recovery unit 62 that is formed on both the left and right sides of the storage unit 61 and collects the condensed water and flows it down to the storage unit 61. The storage unit 61 includes a bottom surface 63, a wall body 64 erected at the front end of the bottom surface 63, a wall body 65 erected at the rear end of the bottom surface 63, and a pair of erections at both left and right ends of the bottom surface 63. The wall body 66 is formed. Further, the collection unit 62 is formed by a slope 67 inclined downward toward the storage unit 61 and wall bodies 64 and 65. Both the storage unit 61 and the recovery unit 62 are open to the atmosphere, and are configured to promote heat exchange between condensed water and the atmosphere. Moreover, heat exchange can be accelerated | stimulated by making the material of the storage tank 60 into a thing with high heat conductivity, such as copper.

  A central portion in the left-right direction of the wall body 64 is a weir 64 a having a height lower than that of other portions of the wall body 64 and the other wall bodies 65 and 66. For this reason, if condensed water accumulates in the storage part 61 to the height of the weir 64a, the condensed water passes over the weir 64a and flows out of the storage tank 60. That is, by providing the weir 64a, the position where the condensed water flows out from the storage tank 60 can be easily defined, and the film thickness of the condensed water stored in the storage unit 61 is defined by the height of the weir 64a. be able to.

  Two partition bodies 68 extending from the left and right ends of the weir 64 a to the front of the wall body 65 toward the rear are erected on the bottom surface 63 of the storage portion 61. For this reason, as shown by an arrow in FIG. 2B, the condensed water that has flowed into the storage unit 61 from the recovery unit 62 once detours to the rear side and reaches the weir 64a. That is, by providing the partition body 68, the flow path from the inflow position to the weir 64a can be made longer than the case where the condensed water flows directly from the inflow position to the reservoir 61 to the weir 64a. Can do. As a result, the residence time of the condensed water in the storage unit 61 becomes longer, the amount of heat exchange between the condensed water in the storage unit 61 and the atmosphere increases, and the condensed water can be heated to a higher temperature. In addition, although the height of the partition 68 can be set freely, if it is made higher than the weir 64a, it is possible to reliably prevent the condensed water from going over the partition 68 and going directly to the weir 64a. Is preferred.

(Saddle member)
Basically, the storage tank 60 as shown in FIGS. 2A and 2B is adopted as the first storage tank 60A, the second storage tank 60B and 60C, and the condensed water flowing out from the weir 64a flows down to the gas pipe 50. If it arranges to do, it is enough. However, in the present embodiment, as shown in FIG. 3, a plurality of first storage tanks 60 </ b> A are also provided in correspondence with the plurality of intermediate medium heaters 10. In order to collect the condensed water from the plurality of first storage tanks 60 </ b> A and flow down to the gas pipe 50, a gutter member 70 is provided. Hereinafter, the flange member 70 will be described. In addition, when the 2nd storage tank 60B or 60C is provided with two or more, you may provide the member similar to the eaves member 70 with respect to the 2nd storage tank 60B and 60C.

  FIG. 3 is a plan view showing the arrangement of the first storage tank 60A and the eaves member 70, and FIG. 4 is a perspective view showing a part of the eaves member 70 in detail. In FIG. 3, the flow of condensed water is indicated by arrows. In the present embodiment, six sets of two intermediate medium warmers 10 are arranged side by side, and one first storage tank 60 </ b> A is provided for each set of the intermediate medium warmer 10. It is arranged vertically below. And the dredging member 70 which collects the condensed water which flowed out from each 1st storage tank 60A, and guides it to the 1st heating part 50a of the gas piping 50 is provided.

  The eaves member 70 includes six receiving portions 71 that receive the condensed water flowing out from each first storage tank 60 </ b> A, a merging portion 72 to which the six receiving portions 71 are connected, and a front side from the left and right central portion of the merging portion 72. And an inclined portion 73 that is inclined downward toward the gas pipe 50. Each receiving part 71 is connected to the weir 64 a of the first storage tank 60 </ b> A, receives the condensed water that has passed over the weir 64 a, and guides the condensed water to the joining part 72. The condensed water collected in the merging portion 72 flows down from the inclined portion 73 to the first heating portion 50a of the gas pipe 50.

  As shown in FIG. 4, a weir 74 is provided at the boundary between the merging portion 72 and the inclined portion 73, and the condensed water that has passed over the weir 74 flows down the inclined portion 73. By providing the weir 74, the residence time of the condensed water in the receiving part 71 and the confluence | merging part 72 can be lengthened. In addition, two collar-shaped water stop portions 51 are provided on the outer peripheral surface of the gas pipe 50. The two water stop portions 51 are formed at positions slightly outside the left and right ends of the inclined portion 73 in a top view. By providing such a water stop part 51, the condensed water flowing down from the inclined part 73 to the gas pipe 50 is prevented from flowing outside the water stop part 51 in the axial direction of the gas pipe 50. The re-collection of the condensed water by the storage tank 60B becomes easy. In addition, when the gas piping 50 is inclined and arrange | positioned at an axial direction, the water stop part 51 should just be provided only in the lower side.

  FIG. 5 is a cross-sectional view for explaining a preferred arrangement of the eaves member 70. Specifically, the positional relationship between the inclined portion 73 and the gas pipe 50 in a cross section orthogonal to the axial direction of the gas pipe 50 is shown. FIG. An intersection point P between the gas pipe 50 and a straight line that extends vertically downward from the tip of the inclined portion 73 is a range R of 45 degrees in the circumferential direction from the apex Q of the gas pipe 50 to the base end side (left side in the drawing). It is preferable to be located within. This is because by doing so, the condensed water flowing down the inclined portion 73 flows evenly on both the left and right sides of the gas pipe 50, so that the natural gas NG in the gas pipe 50 can be uniformly heated. Because. In particular, as shown in FIG. 5, the eaves member 70 is arranged so that the inclination angle of the inclined portion 73 from the horizontal plane is 45 degrees and the position of the intersection P is 45 degrees from the apex Q (the left end of the range R). By doing so, the condensed water can be made to flow evenly to the left and right sides more reliably.

  By providing the eaves member 70 described above with respect to the first storage tank 60A, the condensed water flowing out from the plurality of first storage tanks 60A can be collected and allowed to flow down to the first heating unit 50a of the gas pipe 50. it can. However, it is not essential to provide such a saddle member 70, and the condensed water may flow down from each first storage tank 60 to the gas pipe 50 individually.

(Derivation of necessary bottom area of storage part)
Condensed water stored in the storage tank 60 can be heated to substantially the same temperature as the outside air temperature only by exchanging heat with the atmosphere by ensuring sufficient residence time in the storage unit 61. However, if the area of the bottom surface 63 of the reservoir 61 (hereinafter simply referred to as “bottom area”) is too small, the inflowing condensed water will flow out of the weir 64a without being sufficiently heated. Therefore, the bottom area of the reservoir 61 that can be raised to the same temperature as the outside air temperature while the condensed water stays in the reservoir 61 is derived.

  The present applicant conducted an experiment in which water at 0 ° C. was heated by heat exchange with the atmosphere. This was performed under a total of 6 conditions. The result is shown in FIG. As is apparent from the results of FIG. 6, the time required for the water at 0 ° C. to reach the same temperature as the outside air temperature is hardly affected by the outside air temperature, but can be greatly affected by the thickness of the liquid film. I understood.

Therefore, based on the results of this experiment, an attempt was made to approximately represent the residence time required for water at 0 ° C. to reach the same temperature as the outside air temperature as a function of the average liquid film thickness. At this time, additional experimental data were also obtained when the average liquid film thickness was 0.15 m and 0.2 m. As a result, the formula shown in the figure was obtained as an approximate formula suitable for the four data shown in FIG. The correlation coefficient of this approximate expression is R ² = 1.0, which indicates that the approximate expression fits well with experimental data.

Here, the average liquid film thickness of the condensed water in the reservoir 61 is t [m], the amount of condensed water generated per unit time is Q [m ³ / min], and the bottom area of the reservoir 61 is S [ m ² ], the required residence time T [min] is calculated from the approximate expression shown in FIG.
T ≧ 2044t−16.2
It is.
When the time has elapsed by St / Q [min], the condensed water in the storage unit 61 is replaced with newly generated condensed water.
St / Q ≧ 2044t-16.2
It is necessary to satisfy.
By transforming this equation, the following equation (1) that defines the required bottom area of the storage portion 61 is obtained.
S ≧ (2044-16.2 / t) Q (1)
If it is the storage part 61 which has the bottom area which satisfy | fills Formula (1), the condensed water in the storage part 61 can be raised to the temperature substantially the same as external temperature. In the actual design of the storage tank 60, the height of the weir 64a may be used as the average liquid film thickness t.

(Feedback control of vaporized gas heater)
The feedback control of the vaporized gas heater 30 will be described with reference back to FIG. The liquefied gas vaporizer 1 includes a thermometer 80 for measuring the temperature of the natural gas NG in the gas pipe 50 on the downstream side of the vaporized gas heater 30, and a vaporized gas heater based on the measured value by the thermometer 80. Control means 90 for controlling the operation of the warmer 30 is further provided.

  Specifically, the thermometer 80 is provided further downstream than the third heating unit 50c of the gas pipe 50, and the measured value by the thermometer 80 is constant at the target temperature of natural gas NG of 5 ° C. Is preferred. Therefore, the control unit 90 feedback-controls the motor 33 of the vaporized gas warmer 30 so that the value measured by the thermometer 80 is constant at 5 ° C. By doing so, the natural gas NG can be reliably maintained at the target temperature of 5 ° C.

  In particular, in the present embodiment, among the first warming part 50a, the second warming part 50b, and the third warming part 50c in which the natural gas NG is warmed by the condensed water, the third warming part located on the most downstream side. A thermometer 80 is provided further downstream than the warm part 50c. That is, even if the degree of warming of the natural gas NG in the first warming part 50a, the second warming part 50b, and the third warming part 50c changes due to fluctuations in the outside air temperature, etc. The feedback control considering all of the above is executed. For this reason, the temperature of the natural gas NG can be reliably maintained at the target temperature. However, the position of the thermometer 80 is not limited to this.

(Modification of storage tank)
A modification of the storage tank 60 will be described with reference to FIGS. 8A, 8B, 9A, and 9B. In these drawings, the flow of condensed water is indicated by arrows.

  A storage tank 60 shown in FIGS. 8A and 8B is obtained by changing the shape of the partition 68 provided in the storage unit 61. Specifically, the meandering flow path is formed in the storage portion 61 by making the shape of the partition 68 a shape that folds the flow path of the condensed water multiple times. For this reason, the flow path from the position where the condensed water flows into the storage portion 61 to the weir 64a becomes longer, and the residence time of the condensed water can be increased.

  As a further device for increasing the residence time of the condensed water, as shown in FIGS. 9A and 9B, the height of the condensed water flow path formed by the partition 68 is higher than the walls 64, 65, 66 and the partition 68. It is conceivable to provide an intermediate weir 69 having a low height. 9A and 9B, the partition body 68 is indicated by a thick line in order to clarify the distinction between the partition body 68 and the intermediate weir 69. By providing such an intermediate weir 69, in order for the condensed water to reach the weir 64a from the position where the condensed water flows into the storage unit 61, it is necessary for the condensed water to accumulate to a height that can overcome each intermediate weir 69. It becomes possible to further increase the residence time of the condensed water in 61. The height of the intermediate weir 69 may be basically the same as that of the weir 64a, but may be different from that of the weir 64a.

(effect)
As described above, according to the liquefied gas vaporizer 1 of the present embodiment, the vaporized gas that heats the natural gas NG by using the condensed water generated on the surface of the heat transfer tube 11 of the intermediate medium heater 10. The power consumption of the heater 30 can be reduced. Furthermore, if the natural gas NG can be raised to the target temperature only by heating with condensed water, the vaporized gas heater 30 can be eliminated. In addition, since the condensed water flows down to the gas pipe 50 only by gravity, no additional power is required. In addition, since the heat of the atmosphere is used to heat the condensed water, no additional power is required for this. That is, according to the liquefied gas vaporizer 1, the condensed water generated on the surface of the heat transfer tube 11 can be effectively used, and the power consumption can be effectively reduced. In addition, such a liquefied gas vaporization apparatus 1 aims at reduction of power consumption using the heat of air | atmosphere, and is especially suitable for use in a warm area.

  In the present embodiment, as the storage tank 60, the condensed water generated on the surface of the heat transfer tube 11 is caused to flow down to the gas pipe 50 in addition to the first storage tank 60 </ b> A that is collected before flowing down to the gas pipe 50. Second storage tanks 60B and 60C for recovering condensed water again are further provided. For this reason, the natural gas NG using condensed water can be heated a plurality of times, and the power consumption can be more effectively reduced.

(Overall configuration of liquefied gas vaporization system)
Next, an embodiment of a liquefied gas vaporization system in which the above-described liquefied gas vaporizer 1 is combined with a binary power generator will be described. FIG. 10 is a schematic diagram showing the overall configuration of the liquefied gas vaporization system. The liquefied gas vaporization system 100 condenses the vapor of the working fluid used in binary power generation using the cold heat of the condensed water stored in the first storage tank 60A of the liquefied gas vaporizer 1. FIG. 10 is a schematic view of the liquefied gas vaporization system 100 as viewed from the side, but for convenience, the vaporization unit 102 and the condensation unit 105 have a piping shape viewed from above.

  The liquefied gas vaporization system 100 includes a circulation pipe 101 disposed between the first storage tank 60A provided in the liquefied gas vaporizer 1 and the ground, and the inside of the circulation pipe 101 is used as a working fluid. Ammonia is flowing. The ammonia circulating in the circulation pipe 101 changes in phase between, for example, ammonia gas having a temperature of 10 ° C. and a pressure of 0.8 MPa and liquefied ammonia having a temperature of 10 ° C. and a pressure of 0.1 MPa. The working fluid is not limited to ammonia, and any other fluid may be used as long as it is a fluid that changes phase between a gas phase and a liquid phase at room temperature.

  The liquefied gas vaporization system 100 is further connected to an evaporator 102 that evaporates liquefied ammonia to generate ammonia gas, a turbine 103 that is rotationally driven by the ammonia gas generated by the evaporator 102, and a rotating shaft of the turbine 103. It has the generator 104, the condensation part 105 which condenses the ammonia gas discharged | emitted from the turbine 103, and produces | generates liquefied ammonia, and the pump 106 for pumping liquefied ammonia.

  The evaporating unit 102 is configured by folding the circulation pipe 101 a plurality of times around 20 m underground. Since the temperature is maintained substantially constant throughout the year in the ground, a stable power generation amount can be obtained throughout the year by providing the evaporation unit 102 in the ground. In order to suppress the installation area of the liquefied gas vaporization system 100, the range in which the evaporation unit 102 is provided is preferably within a region immediately below the installation range of the plurality of first storage tanks 60A. In order to increase the efficiency of heat exchange, it is preferable that the number of passes of the circulation pipe 101 in the evaporator 102 is about 8 to 10 passes, and the interval between the passes is about 5 m or more. In addition, the installation depth of the evaporation part 102 is not limited to 20 m underground, What is necessary is just the range of about 10-30 m underground.

  The condensing unit 105 is configured by bending the circulation pipe 101 a plurality of times so that the circulation pipe 101 passes through the plurality of first storage tanks 60 </ b> A provided a plurality of times. Specifically, the circulation pipe 101 in the condensing unit 105 is configured by connecting ends of two straight pipe parts 101a adjacent to each other by a curved pipe part 101b, and the straight pipe part 101a is a first storage. It passes through the condensed water in the storage part 61 of the tank 60A. By carrying out like this, heat exchange with the condensed water in the storage part 61 of 60 A of 1st storage tanks and the ammonia gas which flows through the circulation piping 101 can be accelerated | stimulated. From the viewpoint of heat exchange, it is preferable that the circulation pipe 101 is completely immersed in the condensed water, but the circulation pipe 101 may partially protrude from the water surface of the condensed water.

  FIG. 11 is a perspective view showing a part of the condensing unit 105, and shows a part related to the first storage tank 60A located in the lower left in FIG. Since the configuration of the first storage tank 60A is basically the same as that shown in FIG. 2A, only the main points will be described here.

  In the circulation pipe 101, heat exchange is performed between the ammonia gas and the condensed water as described above in a portion that passes through the condensed water stored in the storage portion 61 of the first storage tank 60 </ b> A. As a result, the ammonia gas is condensed to produce liquefied ammonia, and the temperature of the condensed water rises from 0 ° C. to 5 ° C., for example.

  As described above, when the ammonia gas is condensed by the cold heat of the condensed water in the first storage tank 60A, the function of the condensing unit 105 is lowered when the temperature of the condensed water is increased by heat exchange with the atmosphere. For this reason, at least the storage part 61 of the first storage tank 60 </ b> A is thermally insulated, and more preferably, the entire first storage tank 60 </ b> A including the recovery part 62 is thermally insulated. The heat insulation construction here includes configuring the first storage tank 60A with stainless steel or resin having a relatively low thermal conductivity, or providing the first storage tank 60A with a heat insulating material. In addition, the eaves member 70 (see FIG. 3) connected to the downstream side of the first storage tank 60A promotes heat exchange between the condensed water and the atmosphere and raises the temperature of the condensed water. It is preferably composed of high aluminum, copper or the like.

  In the first storage tank 60A, the efficiency of heat exchange with the ammonia gas in the circulation pipe 101 improves as new condensed water is sequentially supplied. Therefore, in order to shorten the residence time of the condensed water in the storage part 61 of the first storage tank 60A, the partition 68 as shown in FIG.

  On the other hand, for the circulation pipe 101, the thermal conductivity of the part located outside the storage part 61 of the first storage tank 60 </ b> A may be made smaller than the thermal conductivity of the part located inside the storage part 61. By doing so, heat exchange between the condensed water stored in the storage unit 61 and the ammonia gas in the circulation pipe 101 can be promoted, and once condensed liquefied ammonia is vaporized again by heat exchange with the atmosphere. Can be suppressed.

  According to the liquefied gas vaporization system 100 configured as described above, it is possible to generate electric power by utilizing the cold heat and the underground heat (or geothermal heat) of the condensed water generated in the liquefied gas vaporizer 1. Here, “geothermal” refers to heat stored in a relatively shallow underground part using solar energy as a heat source, while “geothermal” generally refers to volcanic activity. It refers to what is stored in the interior of the earth (generally deeper than the target area of geothermal heat). The power thus obtained is used as driving power for the fan 12 of the intermediate medium warmer 10 and the fan 32 (see FIG. 1) of the vaporized gas warmer 30, thereby further reducing the power consumption in the liquefied gas vaporizer 1. It can be effectively reduced.

Next, the specification of the circulation piping 101 is examined. FIG. 12 is a graph showing the relationship between the diameter of the circulation pipe 101 (hereinafter simply referred to as “pipe diameter”) and the pressure loss. After obtaining the exchange heat necessary for the temperature of the condensed water to rise from 0 ° C. to 5 ° C., if this exchange heat is balanced between the ammonia side and the condensed water side, the necessary ammonia flow rate is obtained as 800 kg / h. Based on this ammonia flow rate, the heat transfer area required for twisting out the exchange heat amount on the ammonia side was determined.
here,
Exchange amount of ammonia = ammonia flow rate × heat transfer area Heat transfer area = pipe diameter × pipe length.

  As is apparent from FIG. 12, the pressure loss decreases as the pipe diameter increases. Since it is generally desirable to suppress the pressure loss to about 10 kPa or less, the pipe diameter is preferably about 0.05 m or more. On the other hand, if the pipe diameter is larger than the height of the weir 64a of the first storage tank 60A, the circulation pipe 101 comes out of the surface of the condensed water in the storage section 61, so the pipe diameter is the height of the weir 64a (for example, 0). .2m) or less.

  FIG. 13 is a graph showing the relationship between the ammonia flow rate and the pressure loss or the number of passes. After obtaining the exchange heat necessary for the temperature of the condensed water to rise from 0 ° C. to 5 ° C., the flow rate of ammonia and the pressure loss or the number of passes are determined under the condition of constant exchange heat and pipe diameter (0.15 m). Sought the relationship. As is clear from FIG. 13, the heat transfer rate increases as the ammonia flow rate increases, so that the required pipe length is shortened and the number of passes is also reduced. In addition, the pressure loss tends to increase as the ammonia flow rate increases, but the value is significantly lower than 10 kPa, so the effect is considered to be small.

  FIG. 14 is a graph showing the relationship between the ammonia flow rate and the pressure loss or exchange heat quantity. After obtaining the exchange heat necessary for the temperature of the condensed water to rise from 0 ° C. to 5 ° C., when the ammonia flow rate is changed under the condition that the pipe diameter is 0.15 m, the number of passes is constant, and the number of passes is nine. The exchange heat quantity on the ammonia side was calculated. If the exchange heat quantity on the ammonia side does not exceed the exchange heat quantity required for raising the condensed water, the condensed water will not rise to 5 ° C. Therefore, the ammonia flow rate at which the exchange heat amount on the ammonia side is equal to or greater than the exchange heat amount required for increasing the temperature of the condensed water was determined.

  As apparent from FIG. 14, the pressure loss tends to increase as the ammonia flow rate increases. Further, the maximum amount of heat that the condensed water can exchange heat from the amount of condensed water generated was determined as the maximum amount of condensed water exchanged in the figure. If the ammonia-side exchange heat quantity is less than the condensate maximum exchange heat quantity, some of the cold heat of the condensate is wasted. For this reason, it is preferable that the ammonia flow rate is about 800 kg / h or more so that the exchange heat amount of ammonia is not less than the maximum exchange heat amount of condensed water.

  FIG. 15 is a graph showing the relationship between the ammonia flow rate and the pressure loss or exchange heat quantity. The calculation conditions are almost the same as in FIG. 14 except that the pipe diameter is 0.05 m. When the pipe diameter is 0.05 m, it is necessary to increase the number of passes because the exchange heat quantity on the ammonia side cannot be made equal to or greater than the maximum exchange heat quantity of condensed water while suppressing the pressure loss to 10 kPa or less.

(Other embodiments)
The present invention is not limited to the above embodiment, and the elements of the above embodiment can be appropriately combined or variously modified without departing from the spirit of the present invention.

  For example, in the above embodiment, as the storage tank 60, the condensed water generated on the surface of the heat transfer tube 11 is caused to flow down to the gas pipe 50 in addition to the first storage tank 60 </ b> A that is collected before flowing down to the gas pipe 50. It was set as the structure which further provided the 2nd storage tanks 60B and 60C which collect | recover condensed water again. However, only one of the first storage tank and the second storage tank may be provided as the storage tank 60, and the number of the second storage tanks is not limited to two, but one or three or more. It may be. As a form in which only the second storage tank is provided without providing the first storage tank, for example, the gas pipe 50 is arranged vertically below the heat transfer pipe 11 of the intermediate medium heater 10, and the gas is directly supplied from the heat transfer pipe 11. It is conceivable that the condensed water dropped on the pipe 50 is collected in the second storage tank.

  Moreover, in the said embodiment, although the vaporized gas warmer 30 which heats the natural gas NG in the gas piping 50 was provided, the natural gas NG in the gas piping 50 reaches target temperature only by the heating by condensed water. In this case, the vaporized gas heater 30 may be omitted. Further, the vaporized gas heater 30 is not limited to the air temperature type, and a heater using a heat medium other than air or a heater may be employed. Furthermore, the arrangement position of the vaporized gas heater 30 is not limited to the position illustrated in FIG. 1, and can be set to an appropriate position of the gas pipe 50.

  Moreover, the specific structure which collect | recovers condensed water and makes it flow down to the gas piping 50 can be changed suitably. For example, the collection unit 62 may not be provided in the storage tank 60, and the entire storage unit 61 may be provided, or a guide member for guiding condensed water to the storage tank 60 may be provided separately. Further, not only the condensed water flows down from the storage tank 60 to the gas pipe 50 by another member such as the eaves member 70, but also a member such as the inclined portion 73 may be integrally formed with the storage tank 60. Furthermore, the gas pipe 50 is arranged vertically below the weir 64a of the storage tank 60, and the form reaching the gas pipe 50 by dropping the condensed water flowing out of the storage tank 60 is also "flow down to the gas pipe" in the present invention. It is included in the concept.

  In the above embodiment, the intermediate medium warmer 10 vaporizes the liquid intermediate medium. However, it is not essential to vaporize the liquid intermediate medium by the intermediate medium heater 10. For example, when an antifreeze such as brine is used as an intermediate medium, the intermediate medium heater 10 may simply raise the temperature without changing the phase of the liquid intermediate medium.

  In the above embodiment, only the use of the condensed water generated in the intermediate medium warmer 10 has been described. However, the condensed water generated in the vaporized gas warmer 30 may be effectively used in the same manner. .

DESCRIPTION OF SYMBOLS 1 Liquefied gas vaporizer 10 Intermediate | middle medium heater 11 Heat exchanger tube 20 Liquefied gas evaporator 30 Vaporized gas heater 50 Gas piping 60 Storage tank 60A 1st storage tank 60B 2nd storage tank 60B 2nd storage tank 61 Storage part 64 Wall body 64a Weir 65 Wall body 66 Wall body 68 Partition body 69 Intermediate weir 70 Anchor member 73 Inclined portion 80 Thermometer 90 Control means 100 Liquefied gas vaporization system 101 Circulation piping 102 Evaporating portion 103 Turbine 104 Generator 105 Condensing portion

Claims (16)

An intermediate medium heater for heating the intermediate medium flowing in the heat transfer tube by heat exchange with the heating gas;
A liquefied gas evaporator that vaporizes a liquefied gas to generate a vaporized gas by heat exchange with the intermediate medium heated by the intermediate medium heater;
A gas pipe through which the vaporized gas generated by the liquefied gas evaporator flows;
With
The heating gas contains water vapor, and the surface temperature of the heat transfer tube is lower than the dew point of the heating gas, so that condensed water is generated on the surface of the heat transfer tube,
In a state where the condensed water is stored in a storage part of a storage tank disposed at a position lower than the heat transfer pipe, after being heated by heat exchange with the air having a temperature higher than that of the condensed water, the condensed water is more than the storage tank. A liquefied gas vaporizer characterized in that the vaporized gas in the gas pipe is heated by flowing down to the gas pipe at a low position by its own weight.   2. The liquefied gas vaporizer according to claim 1, wherein the storage tank is provided with a first storage tank that collects the condensed water generated on the surface of the heat transfer tube before flowing down to the gas pipe.   3. The liquefied gas vaporizer according to claim 2, wherein at least one second storage tank is provided as the storage tank for recovering again the condensed water flowing down to the gas pipe. A part of the wall forming the storage part is a weir having a lower height than the other part,
The liquefied gas vaporizer according to any one of claims 1 to 3, wherein the condensed water in the reservoir reaches the gas pipe by overcoming the weir.   The liquefied gas vaporizer according to claim 4, further comprising a gutter member that guides the condensed water that has passed over the weir to the gas pipe. The gas pipe is a circular pipe, and the flange member has an inclined portion for flowing the condensed water toward the gas pipe,
In the cross section orthogonal to the axial direction of the gas pipe, the intersection of the gas pipe and the straight line drawn vertically downward from the tip of the inclined portion extends in the circumferential direction from the apex of the gas pipe to the base end side of the inclined portion. The liquefied gas vaporizer according to claim 5, which is located within a range of 45 degrees.   The storage part is provided with an intermediate weir in which the condensed water needs to get over the flow path from the position where the condensed water flows into the storage part to the weir. The liquefied gas vaporizer according to the item.   Compared with the case where the condensed water flows directly from the inflow position to the storage portion to the weir, the reservoir has a partition that lengthens the flow path from the inflow position to the weir. The liquefied gas vaporizer according to any one of claims 4 to 7, which is provided.   The liquefied gas vaporizer according to any one of claims 1 to 8, further comprising a vaporized gas heater that heats the vaporized gas in the gas pipe. A thermometer for measuring the temperature of the vaporized gas in the gas pipe on the downstream side of the vaporized gas heater;
Control means for controlling the operation of the vaporized gas heater so that the measured value of the vaporized gas by the thermometer is constant;
The liquefied gas vaporizer according to claim 9, further comprising: When the average liquid film thickness of the condensed water in the storage part is t, the amount of the condensed water generated per unit time is Q, and the bottom area of the storage part is S, the storage tank has the following formula (1 The liquefied gas vaporizer according to any one of claims 1 to 10, wherein
S ≧ (2044-16.2 / t) Q (1) A liquefied gas vaporizer according to claim 2;
A circulation pipe that is disposed between the first storage tank and the ground, and in which the working medium flows;
A generator that operates by steam of the working medium vaporized by geothermal or underground heat;
A liquefied gas vaporization system comprising:
The circulatory pipe has a condensing part that passes through the condensed water stored in the first storage tank, and the vapor of the working medium is condensed in the condensing part. Gas vaporization system.   The liquefied gas vaporization system according to claim 12 with which heat insulation construction is made to at least said storage part among said 1st storage tanks.   14. The liquefied gas vaporization system according to claim 12, wherein a thermal conductivity of a portion of the condensing unit located outside the storage unit is smaller than a thermal conductivity of a portion of the condensing unit located within the storage unit. . A plurality of the first storage tanks are provided;
The liquefied gas vaporization system according to any one of claims 12 to 14, wherein the condensing unit passes all of the plurality of first storage tanks a plurality of times.   When a weir having a lower height than other parts is provided in a part of the wall forming the storage part, the pipe diameter of the condensing part is not less than 0.05 m and not more than the height of the weir. The liquefied gas vaporization system according to any one of claims 12 to 15.

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