JP2012057797A - Mist diffusion preventing structure of liquefied gas evaporator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent diffusion of mist generated from a liquefied gas evaporator with a simplified structure.SOLUTION: In a mist diffusion preventing structure 50 preventing diffusion of mist from a liquefied gas evaporator 1, the liquefied gas evaporator 1 is supported in a raised state from a reference plane 3, a lower space 5 is formed between the liquefied gas evaporator 1 and the reference plane 3 and a shield 11 erected from the reference plane 3 is provided outside the lower space 5. An induction air flow forming mechanism 51 is further provided, so that an atmosphere rising from the inner side of the shield 11 is induced to the formed induction air flow.

Description

  The present invention relates to a structure for preventing diffusion of fog generated from a liquefied gas evaporator.

  For example, as a means for vaporizing a low-temperature liquefied gas such as LNG, LPG, liquid nitrogen, or liquid oxygen, a so-called air temperature type liquefied gas evaporator is generally used. Such a liquefied gas evaporator has a configuration in which a liquefied gas is passed through a meandering heat transfer tube, heat is exchanged between the liquefied gas and outside air (air) through the heat transfer tube, and the temperature of the liquefied gas is raised to room temperature. ing.

  During the operation of the liquefied gas evaporator as described above, the surface temperature of the heat transfer tube is cooled by the internal liquefied gas, so that it is significantly lower than the outside air, particularly on the liquefied gas inlet side. For this reason, the air around the heat transfer tube is cooled, and depending on the weather conditions, the water vapor contained in the air is rapidly cooled below the saturation temperature, and white smoke mist may be generated. Since this mist is heavier than air, it naturally sinks below the liquefied gas evaporator and easily spreads around the ground. For example, if there is a road near the liquefied gas evaporator, the mist will flow out onto that road. As a result, visibility may deteriorate and traffic may be obstructed. Moreover, it may become an obstacle to work near the liquefied gas evaporator, for example, monitoring of a measuring instrument or operation of a valve. Furthermore, if fog that looks like smoke is generated in a place that is easily visible to the public, it may cause anxiety and disgust to the general population and may lead to misunderstandings such as accidents. In this way, white smoke mist has an undesirable effect on the surrounding environment, so it is necessary to prevent diffusion.

  Conventionally, as a countermeasure for preventing the diffusion of fog, for example, by blowing heated air below the liquefied gas evaporator and heating the atmosphere below the liquefied gas evaporator, the mist is erased or fog is generated. A configuration for preventing this has been proposed (see Patent Document 1). Moreover, the structure which collect | recovers fog (cold air) by attracting | sucking the atmosphere below a liquefied gas evaporator is proposed (refer patent document 2). Furthermore, the structure which provides the heater (heat exchanger) which heats the atmosphere under the liquefied gas evaporator is proposed (refer patent document 3).

JP-A-9-165588 JP 2002-228096 A JP 2003-14195 A

  However, the conventional configuration has a problem that the required equipment and the number of parts are large and the equipment cost is high, or the running cost is high, which may be disadvantageous economically.

  The present invention has been made in view of the above points, and an object thereof is to provide a mist diffusion prevention structure for a liquefied gas evaporator that can prevent mist diffusion with a simple configuration.

  In order to solve the above-described problems, according to the present invention, a mist diffusion preventing structure for preventing mist from diffusing from a liquefied gas evaporator, the liquefied gas evaporator being supported while being lifted from a reference plane. And a shielding member standing upright from the reference surface outside the lower space formed between the liquefied gas evaporator and the reference surface, wherein the shielding member is provided in at least a part of the lower space. The mist of the liquefied gas evaporator is provided with an induced airflow forming mechanism that is provided so as to oppose and that is configured to draw an atmosphere rising from the inside of the shield to the induced airflow. An anti-diffusion structure is provided.

  In addition, a wall body may be provided on the outer side along the outer surface of the shield, and the guided airflow forming mechanism may supply gas to a gap between the shield and the wall.

  According to the present invention, it is possible to effectively prevent the diffusion of fog around the liquefied gas evaporator. The structure is simple, equipment costs, running costs, etc. can be reduced, which is economical.

It is a schematic side view explaining the structure of a liquefied gas evaporator and a fog diffusion prevention structure. It is a schematic plan view explaining the structure of a liquefied gas evaporator and a fog diffusion prevention structure. It is a schematic side view explaining the structure of the fog diffusion prevention structure concerning 2nd embodiment provided with the suction mechanism. It is a schematic plan view explaining the structure of the fog diffusion prevention structure concerning 2nd embodiment which provided the suction mechanism. It is a schematic side view explaining the structure of the fog diffusion prevention structure concerning 3rd embodiment provided with the induced airflow formation mechanism. It is a schematic perspective view of an induced airflow formation mechanism. It is a schematic perspective view of the induced airflow formation mechanism concerning another embodiment. It is a schematic side view explaining the structure of the fog diffusion prevention structure concerning 4th embodiment provided with the blowing airflow formation mechanism. It is a schematic plan view explaining the structure of the fog diffusion prevention structure concerning 4th embodiment provided with the blowing airflow formation mechanism. It is a schematic side view explaining the structure of the fog diffusion prevention structure concerning embodiment which lowered | hanged the position of the discharge nozzle of a blowing airflow formation mechanism. It is a schematic plan view explaining embodiment which provided the some liquefied gas evaporator inside the shield. It is a schematic plan view explaining embodiment which made the shield the substantially U shape. It is a schematic plan view of the structure used for the experiment of an Example. It is explanatory drawing (sectional drawing by the II line | wire in FIG. 14) explaining the structure used for the experiment of an Example. It is the graph which showed the measurement result of experiment.

  Hereinafter, an example of the first embodiment of the present invention will be described as an example of a liquefied gas evaporator (LNG vaporizer) in which LNG (Liquid Natural Gas) as an example of liquefied gas is changed to NG (Natural Gas: natural gas). ) Will be described based on the fog diffusion prevention structure provided in (1). As shown in FIG. 1, the liquefied gas evaporator 1 is supported by an evaporator support 2 by being lifted from a reference surface (ground or floor surface) 3 having a substantially horizontal plane, for example. A space (lower space) 5 having a predetermined height H1 is formed between the reference plane 3 and the reference plane 3. In addition, a shield 11 having a predetermined height H2 constituting the fog diffusion preventing structure 10 according to the present embodiment is provided outside the lower space 5.

  The liquefied gas evaporator 1 includes a heat transfer tube 21 through which liquefied gas (LNG) is passed, and a heat transfer tube support 22 that supports the heat transfer tube 21.

  The heat transfer tube 21 has, for example, a plurality of straight tube portions 21a and a plurality of curved portions 21b that connect ends of the straight tube portions 21a. The straight pipe portions 21a are arranged side by side in parallel with the interval in the length direction being substantially vertical. The curved portion 21b is provided so as to connect the upper end portions or the lower end portions of the adjacent straight pipe portions 21a. A liquefied gas introduction path 25 for introducing liquefied gas is connected to one end of the heat transfer tube 21 (the lower end of the straight tube portion 21a located on the leftmost side in the illustrated example), and the other end (the illustrated example). Then, a gas outlet path 26 for connecting the gas (NG) vaporized (evaporated) in the heat transfer tube 21 is connected to the lowermost portion of the straight pipe portion 21a located on the rightmost side.

  The heat transfer tube support 22 includes a lower frame 31 provided on the lower end side of each straight tube portion 21a and an upper frame 32 provided on the upper end portion side of each straight tube portion 21a. The lower frame 31 and the upper frame 32 have, for example, a substantially square shape and are provided substantially horizontally. The heat transfer tube 21 is held in a state where the lower end portion of the straight tube portion 21 a is fixed by the lower frame 31 and the upper end portion of the straight tube portion 21 a is fixed by the upper frame 32.

  The evaporator support 2 includes, for example, four support legs 35 provided in correspondence with the four corners of the lower frame 31, respectively. Each support leg 35 is erected from the reference plane 3. The heat transfer tube support 22 is fixedly supported by the support legs 35 while being lifted from the reference plane 3.

  In the present embodiment, the lower space 5 is a space surrounded by the reference plane 3, the lower frame 31, and the four support legs 35. The height between the lower end of the liquefied gas evaporator 1 and the reference surface 3, that is, the height H1 of the lower space 5 may be about 2 m, for example.

  As shown in FIGS. 1 and 2, the shield 11 is provided so as to surround the entire periphery of the lower space 5, for example, so as to form a substantially square shape in a plan view, that is, a substantially rectangular tube shape. Has been. For example, the four inner side surfaces of the shield 11 are erected from the reference plane 3 in a substantially vertical direction, and are provided so as to be substantially parallel to the four sides of the lower frame 31, respectively. .

  The shield 11 may be formed in a wall shape with a material having high rigidity, such as a metal plate or a concrete plate. For example, a material having flexibility such as cloth or vinyl is used for the steel pipe. You may form by supporting by the support frame formed by etc. That is, the shield 11 may be formed of a material that does not allow air to pass therethrough.

  The shield 11 is disposed at a position spaced apart from the liquefied gas evaporator 1, the evaporator support 2 and the lower space 5. For example, the distance L in the horizontal direction between the inner surface of the shield 11 and the lower space 5 (that is, between the side surface of the lower frame 31 and the inner surface of the shield 11 provided facing the side surface). The distance in the horizontal direction is set to be about 0.5 m or more and about 5 m or less (that is, about 0.5 m ≦ L ≦ 5 m), more preferably about 3 m.

  Further, the height of the shield 11, that is, the height H <b> 2 from the reference surface 3 to the upper edge of the shield 11 is set to a height within a predetermined range. For example, the difference between the height H1 and the height H2 of the lower space 5 described above is set to be about 1.5 m or less (that is, approximately | H1−H2 | ≦ 1.5 m). Therefore, for example, if H1 = 2 m, it may be about 0.5 m ≦ H2 ≦ 3.5 m. For example, it is good also as H1 = H2.

  When the liquefied gas is evaporated by the liquefied gas evaporator 1 having the above-described configuration, first, for example, LNG is introduced as a low-temperature liquefied gas from the liquefied gas introduction path 25 into the heat transfer tube 21. The liquefied gas is directed toward the gas outlet path 26 while alternately flowing through the straight pipe portion 21a and the curved portion 21b. Thus, while the liquefied gas passes through the heat transfer tube 21, heat exchange is performed between the liquefied gas and the air outside the heat transfer tube 21 via the heat transfer tube 21. That is, the liquefied gas is heated by the heat of the air outside the heat transfer tube 21, evaporated and returned to gas, that is, returned to NG, and then led out from the gas outlet 2d.

  On the other hand, the surface of the heat transfer tube 21 and the air in the vicinity of the heat transfer tube 21 are cooled by the cold heat of the internal liquefied gas. Then, depending on the weather conditions, moisture contained in the air near the heat transfer tube 21 is rapidly cooled to the saturation temperature or lower to form a mist, and white smoke mist is generated.

  The generated white smoke mist and the air (cold air) cooled by the heat transfer tube 21 naturally sinks from the liquefied gas evaporator 1 toward the lower space 5. The atmosphere (fog and cold air) accumulated in the lower space 5 passes between the support legs 35, flows out from the lower space 5, and diffuses around the lower space 5, but is blocked by the shield 11. It is done. On the other hand, above and outside the shield 11, there is mist inside the shield 11 and outside air (air) that is warmer than the cold air. The heat inside the shield 11 causes the mist inside the shield 11 to be heated. The temperature is raised above the saturation temperature and returned to the unsaturated state. Thus, the atmosphere in which the white smoke mist has been extinguished (disappeared) overflows (overflows) from the upper edge of the shield 11 and flows out of the shield 11.

  According to the experiments of the present inventors, the temperature distribution in the lower space 5 when the liquefied gas is evaporated by the liquefied gas evaporator 1 is cooled to the lower temperature as the upper side closer to the liquefied gas evaporator 1 is cooled. Further, it is known that the lower side closer to the reference plane 3 is relatively warmer than the upper side. However, outside the lower space 5, for example, the temperature distribution below the height H <b> 2 has a small lower temperature change near the reference plane 3, and remains at a low temperature similar to the lower space 5, but the upper temperature is It has been confirmed that the cold air on the upper side is mixed with the air on the upper side, so that it is relatively warmer than the lower side.

  That is, in the lower space 5, a lot of mist exists on the upper side near the heat transfer tube 21, but if it flows out of the lower space 5, it is considered that a lot of mist accumulates on the lower side near the reference surface 3. However, when fog and cold are blocked by the shield 11 and cannot flow out in the lateral direction, the fog and cold reach the vicinity of the height of the upper edge of the shield 11 and fill the inside of the shield 11. become. On the other hand, outside air (air) warmer than the cool air inside the shield 11 exists above and outside the shield 11. In the state where fog and cold are accumulated inside the shield 11 as described above, the upper side (high place) closer to the height of the upper edge of the shield 11 than the lower side (low side) close to the reference plane 3. The side) is more ventilated, and at this high side, fog and cold air are likely to come into contact with warm outside air and be mixed. For this reason, at high altitudes, the fog and cold are warmed by warm outside air, and the mist is heated to the saturation temperature or higher and returned to the unsaturated state. Further, when the atmosphere in the shield 11 overflows and flows out from the upper edge portion of the shield 11, the outflow atmosphere is relatively warm existing above and outside the upper edge portion of the shield 11. Mixing in contact with outside air. That is, even in the vicinity of the upper edge of the shield 11, the temperature of the flowing out atmosphere can be raised by the outside air. Accordingly, even if mist remains in the flowing atmosphere, the mist can be returned to an unsaturated state and extinguished near the upper edge of the shield 11, that is, when it flows out of the shield 11. It is considered possible.

  According to the fog diffusion preventing structure 10, white smoke-like mist is generated from the liquefied gas evaporator 1 simply by installing a shield 11 having an appropriate height at an appropriate position around the liquefied gas evaporator 1. Even so, the fog can be extinguished naturally and the fog can be effectively prevented from spreading. Because the fog disappears inside the shield 11 (at a lower height than the shield 11 or almost the same height as the upper edge of the shield 11) or when it flows out from the upper edge of the shield 11 to the outside. , Fog is not easily noticeable and can prevent the surrounding environment from being adversely affected.

  Moreover, since it is a simple structure which only installs the shield 11, installation cost is cheap. Furthermore, by using the natural flow of the air current, the mist can be extinguished naturally, and there is no need to use special power for the disappearance of the mist. Therefore, there is no running cost and it is economical.

  Next, an example of the second embodiment according to the present invention will be described. The fog diffusion prevention structure 40 illustrated in FIG. 3 and FIG. 4 is a shield provided at a predetermined position surrounding the liquefied gas evaporator 1 as in the fog diffusion prevention structure 10 according to the first embodiment. 11 is provided. Furthermore, a suction mechanism 41 that sucks the atmosphere inside the shield 11 is provided.

  The suction mechanism 41 includes, for example, a suction nozzle 42 provided along the upper edge portion of the shield 11 and a suction path 43 connected to the suction nozzle 42. On the side surface of the suction nozzle 42, a plurality of suction ports 42a are provided in a line in a direction along the upper edge of the shield 11, for example. A blower 45 such as a blower is interposed in the suction path 43. The downstream end of the suction path 43 is located at a position sufficiently away from the liquefied gas evaporator 1 and the shield 11, that is, exhaust gas discharged from the downstream end of the suction path 43 is transferred to the liquefied gas evaporator 1 and the shield. 11 is provided at a position that does not affect the flow of airflow in the vicinity of 11.

  In such a configuration, during operation of the liquefied gas evaporator 1, most of the mist disappears inside the shield 11 or in the vicinity of the upper edge of the shield 11 in substantially the same manner as in the first embodiment. After that, the atmosphere inside the shield 11 is forcibly sucked by the suction ports 42 a of the suction nozzle 42 at the upper edge of the shield 11 by driving the blower 45. Then, it passes through the suction path 43 and is discharged to a position sufficiently away from the liquefied gas evaporator 1 and the shield 11 and diffused into the atmosphere. In this way, the cool air inside the shield 11 can be reliably discharged, and the mist can be efficiently extinguished. For example, when the wind is too weak, the wind direction is bad, or the like, depending on weather conditions and the like, in the first embodiment, the contact between fog and cold air on the upper side of the shield 11 and relatively warm outside air is insufficient. In addition, since there is a large amount of mist, it may be difficult to eliminate the mist only by contact with relatively warm outside air. The air force is forcibly formed inside the shield 11 or near the upper edge of the shield 11 by the suction force, and the mixing of the fog and cold air with the relatively warm outside air is promoted, so that the fog can be reliably and efficiently produced. Can be extinguished. Further, even when the outside air outside or above the shield 11 is high in humidity, it can be efficiently extinguished by sucking the mist and discharging or collecting it outside the system.

  The suction mechanism includes the suction nozzle 42 and the suction passage 43 and performs suction by the power of the blower 45. However, as a means for generating the suction force, for example, an ejector may be used. For example, an ejector may be provided at the upper edge of the shield 11 instead of the suction nozzle 42.

  Next, an example of the third embodiment according to the present invention will be described. The fog diffusion preventing structure 50 illustrated in FIGS. 5 and 6 is a shield provided at a predetermined position surrounding the liquefied gas evaporator 1, similarly to the fog diffusion preventing structure 10 according to the first embodiment. 11 is provided. Furthermore, a guided airflow forming mechanism 51 that forms a lateral airflow along the outer surface of the shield 11 is provided. For example, the induced airflow forming mechanism 51 supplies a gas such as air to a wall body 52 provided outside along the outer surface of the shield body 11 and a gap 53 between the shield body 11 and the wall body 52. The supply path 55 is provided.

  The outer wall body 52 is provided so as to be erected from the reference surface 3 so as to be substantially parallel to the outer surface of the shielding body 11, for example, at a position spaced apart from each of the four outer surfaces of the inner shielding body 11. Yes. The wall body 52 is formed lower than the shield body 11. That is, it is provided so as to surround the lower portion of the shielding body 11, and the upper end portion of the shielding body 11 is protruded above the wall body 52.

  The supply path 55 is connected to, for example, one end side of the gap 53, and is directed to discharge gas laterally along the gap 53 from one end side to the other end side of the gap 53. Yes. For example, a blower 57 such as a blower is interposed in the supply path 55.

  In such a configuration, during operation of the liquefied gas evaporator 1, most of the mist disappears inside the shield 11 or in the vicinity of the upper edge of the shield 11 in substantially the same manner as in the first embodiment. Be made. On the other hand, on the outside of the shield 11, gas is discharged from the supply path 55 by driving the blower 57, and a lateral airflow is formed in the gap 53. Then, the atmosphere rising from the inside of the shield 11 and flowing out to the outside is attracted to the induced airflow formed in the gap 53 and falls from the outside of the upper end portion of the shield 11. Then, along the outer surface of the shield 11, it flows sideways along with the airflow in the gap 53, and is separated from the shield 11 on the other end side of the gap 53 and diffused into the atmosphere. In this way, by guiding the atmosphere flowing out from the shield 11 by the induced air flow in the gap 53, an air flow of the atmosphere flowing out from the shield 11 is formed in the vicinity of the upper edge of the shield 11, thereby shielding the shielding. Contact between the atmosphere flowing out from the body 11 and the relatively warm outside air can be promoted. For example, even when the wind is too weak or the wind direction is bad, an air current can be forcibly formed in the vicinity of the upper edge of the shield 11 and the mist can be reliably extinguished. For example, if the humidity of the gas discharged from the supply path 55 is reduced in advance and discharged in a dry state, for example, even when the humidity of the outside air existing outside or above the shield 11 is high. It can be effectively extinguished by bringing the mist into contact with the dry gas. Further, for example, if the gas discharged from the supply path 55 is discharged in a preheated state, for example, when the outside air existing outside or above the shield 11 has a high humidity or when the temperature is low. However, by bringing the mist into contact with the heated gas, it can be efficiently warmed and extinguished.

  In the above-described guided airflow forming mechanism, the airflow is discharged from one end of the gap 53. For example, as shown in FIG. Alternatively, the gas may be discharged in opposite directions from both ends. In this case, the induced air currents discharged from both ends of the gap 53 collide with each other in the vicinity of the intermediate portion in the longitudinal direction of the gap 53 and merge to form an induced air current rising from the gap 53. In such a configuration, the atmosphere flowing out from the inner side to the outer side of the shield 11 is attracted to the laterally induced airflow formed in the gap 53 on both sides of the rising induced airflow and descends. In the vicinity of the intermediate portion in the longitudinal direction of the gap 53, the gap is drawn up by the induced airflow rising from the gap 53 and diffused into the atmosphere above the shield 11. Also in this case, the airflow flowing out from the shield 11 can be guided by the induced airflow, the airflow can be forcibly formed in the vicinity of the shield 11, and the fog can be efficiently extinguished.

  In addition, the wall body 52 and the gap 53 are not necessarily provided, and gas may be discharged only in the lateral direction along the outside of the shield body 11. Also in this case, a laterally directed airflow can be formed outside the shield 11, and the airflow flowing out from the shield 11 can be guided outside the shield 11.

  Next, an example of the fourth embodiment according to the present invention will be described. The fog diffusion preventing structure 60 illustrated in FIG. 8 and FIG. 9 is a shield provided at a predetermined position surrounding the liquefied gas evaporator 1 in the same manner as the fog diffusion preventing structure 10 according to the first embodiment. 11 is provided. Furthermore, a blowing airflow forming mechanism 61 is provided for blowing an airflow upward of the shield 11.

  The blow-up airflow forming mechanism 61 is configured to include, for example, a discharge nozzle 62 provided along the upper edge portion of the shield 11 and a supply path 63 connected to the discharge nozzle 62. On the upper surface of the discharge nozzle 62, a plurality of discharge ports 62a for discharging a gas such as air toward the upper side of the shield 11 are provided in a line in the horizontal direction along the upper edge of the shield 11, for example. It has been. Each discharge port 62a is directed to discharge gas in a substantially vertical direction, for example. A blower 65 such as a blower is interposed in the supply path 63.

  In such a configuration, during operation of the liquefied gas evaporator 1, most of the mist disappears inside the shield 11 or in the vicinity of the upper edge of the shield 11 in substantially the same manner as in the first embodiment. Be made. On the other hand, by driving the blower 65, gas is supplied from the supply path 63 into the discharge nozzle 62, and this gas is discharged from the discharge ports 62a all at once. Thereby, an upward air flow (for example, an air curtain) blown up in a substantially vertical direction is formed above the upper edge portion of the shield 11. Then, the atmosphere (cold air) inside the shield 11 is raised from the shield 11 along with the airflow discharged from the discharge port 62a, and is diffused into the atmosphere at a high position above the shield 11. . In this way, the atmosphere near the upper end of the shield 11 is guided by the induced airflow discharged upward from the discharge nozzle 62, and the contact between the atmosphere flowing out of the shield 11 and the relatively warm outside air is promoted. , The fog can be extinguished efficiently. For example, when the wind is too weak or the wind direction is bad, the fog can be reliably extinguished. Further, for example, if the humidity of the gas discharged from the discharge port 62a is reduced in advance and discharged in a dry state, for example, even when the humidity of outside air existing outside or above the shield 11 is high. It can be effectively extinguished by bringing the mist into contact with the dry gas. For example, if the gas discharged from the discharge port 62a is discharged in a preheated state, for example, when the outside air existing outside or above the shield 11 has a high humidity or when the temperature is low. However, by bringing the mist into contact with the heated gas, it can be efficiently warmed and extinguished.

  In the above-described blowing airflow formation mechanism, the discharge nozzle 62 is provided at the upper edge portion of the shield 11. However, the position of the discharge nozzle 62 is not limited to such a location. Provided sideways along the outer surface of the shield 11, directing the discharge port 62a upward, so as to blow up the gas along the outer surface of the shield 11 above the upper edge of the shield 11. Also good. Also in this case, a curtain-shaped induced airflow can be formed above the shield 11. That is, it is possible to promote contact between the atmosphere flowing out from the shield 11 and the relatively warm outside air while guiding the atmosphere inside the shield 11 to the upper side of the shield 11.

  Further, in the above blowing airflow formation mechanism, the gas is blown up above the shield 11 to form the induced airflow. For example, as shown in FIG. 10, the discharge nozzle 62 is provided below the shield 11, The height at which the gas discharged from the discharge port 62a is blown up may be lower than the upper edge of the shield 11. In such a configuration, during operation of the liquefied gas evaporator 1, most of the mist disappears inside the shield 11 or in the vicinity of the upper edge of the shield 11 in substantially the same manner as in the first embodiment. Be made. On the other hand, on the outside of the shield 11, gas is discharged from the discharge ports 62a all at once. As a result, an updraft that is blown up in the form of a curtain toward the substantially vertical direction is formed below the upper edge of the shield 11. In this case, when the atmosphere in the shield 11 flows out from the upper edge of the shield 11 and descends, the gas discharged from the discharge port 62a is blown up in a direction in which this gas flows backward. Collide and be mixed. Further, it is mixed with the ambient air around the shield 11 by being diffused by collision with the gas discharged from the discharge port 62a. In this way, the airflow that is about to flow out from the shield 11 is reliably warmed by being brought into efficient contact with the gas discharged from the discharge port 62 a and the outside air around the shield 11. Therefore, the fog in the air current can be efficiently extinguished. For example, when the wind is too weak or the wind direction is bad, the fog can be efficiently warmed and extinguished. Further, for example, if the humidity of the gas discharged from the discharge port 62a is reduced in advance and discharged in a dry state, for example, even when the humidity of outside air existing outside or above the shield 11 is high. It can be effectively extinguished by bringing the mist into contact with the dry gas. Also in this case, for example, if the gas discharged from the discharge port 62a is discharged in a preheated state, for example, the humidity of the outside air existing outside or above the shield 11 is high, or the temperature is Even if it is low, it can be efficiently warmed and extinguished by bringing the mist into contact with a heated gas.

  As mentioned above, although the example of suitable 1st embodiment-4th embodiment of this invention was each demonstrated, this invention is not limited to the form demonstrated here. It is obvious for those skilled in the art that various changes and modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

For example, in the above embodiment, the liquefied gas evaporator 1 is an evaporator that changes LNG to NG, but the type and structure of the liquefied gas evaporator are not limited to those shown in the above embodiment. For example, the type of liquefied gas or gas to be processed in the liquefied gas evaporator, that is, the fluid to be processed that is passed through the heat transfer tube 21 is not limited to LNG and NG, but other types of fluids such as LPG ( Liquid Petroleum Gas (liquefied petroleum gas) and PG, liquid nitrogen (N ₂ ) and nitrogen gas, or liquid oxygen (O ₂ ) and oxygen gas may be used. That is, a liquefied gas evaporator that returns LPG to PG, a liquefied gas evaporator that returns liquid nitrogen to nitrogen gas, a liquefied gas evaporator that returns liquid oxygen to oxygen gas, and the like may be used.

  In the above embodiment, the case where one liquefied gas evaporator 1 is installed inside the shield 11 has been described, but a plurality of liquefied gas evaporators 1 may be provided inside the shield 11. good. For example, as shown in FIG. 11, three liquefied gas evaporators 1A, 1B, and 1C may be arranged in a row in the horizontal direction (X-axis direction (horizontal direction in FIG. 11)). Further, a lower space 5 is formed between each liquefied gas evaporator 1A, 1B, 1C and the reference plane 3. Also in this case, it is preferable to arrange the shield 11 at a position spaced apart from each of the liquefied gas evaporators 1A, 1B, 1C.

  In the example shown in FIG. 11, the three liquefied gas evaporators 1A, 1B, and 1C have the same configuration, are arranged in this order in the X-axis direction, and are provided at predetermined intervals. Each liquefied gas evaporator 1A, 1B, 1C is provided with the four side surfaces of the lower frame 31 oriented in the direction along the X-axis direction and the Y-axis direction (horizontal direction perpendicular to the X-axis direction), respectively. ing. Then, the distance L1 in the X-axis direction between the lower space 5 of the liquefied gas evaporator 1A and the inner side surface (the surface oriented in the Y-axis direction) of the shield 11 and the lower space 5 of the liquefied gas evaporator 1C and the shield. The distance L2 in the X-axis direction between the inner surface of the body 11 (the surface oriented in the Y-axis direction) is about 0.5 m to about 5 m, and preferably about 3 m. . Further, in the Y-axis direction between the lower space 5 of each of the liquefied gas evaporators 1A, 1B, 1C and the inner side surface (surface directed in the X-axis direction) of the shield 11 located on both sides of each lower space 5 The distances L3 and L4 are arranged to be about 0.5 m or more and about 5 m or less, preferably about 3 m, respectively. Even if it does in this way, the fog which generate | occur | produces from each liquefied gas evaporator 1A, 1B, 1C can be extinguished effectively, and the spreading | diffusion of fog can be prevented.

  In addition, when the plurality of liquefied gas evaporators 1 are provided inside the shield 11 as described above, the various fog diffusion preventing structures 10 and 40 described in the first to fourth embodiments described above. , 50, 60 may be applied.

  In the above embodiment, the shape of the shield 11 is substantially rectangular in plan view, but is not limited to this shape, and may be, for example, a circle. Further, although the shield 11 is provided so as to surround the entire periphery of the lower space 5 of the liquefied gas evaporator 1, it may be provided so as to face only a part of the periphery of the lower space 5. For example, as shown in FIG. 12, a shield 11 ′ having a substantially U shape in plan view is formed, and the three inner surfaces of the shield 11 ′ are opposed to each other in three directions around the lower space 5. May be. Also in this case, the horizontal distance L between the three inner surfaces of the shield 11 and the lower space 5 should be about 0.5 m to 5 m, more preferably about 3 m, respectively. preferable. Further, for example, a shielding body having a substantially L shape in a plan view may be formed, and two inner side surfaces may be opposed to each other in two directions around the lower space 5, or the shielding body may be a single flat plate. Thus, it may be provided so as to face only one side portion around the lower space 5. In these cases also, the fog generated from the liquefied gas evaporator 1 can be eliminated on the side where the shield is provided, and the fog can be prevented from flowing out of the shield. For example, when roads and private houses exist only on one side of the liquefied gas evaporator 1, and the other side is a factory site, a shield should be provided at least on the side where the roads and private houses exist. In, the shield may not be provided and may be left open. The shape and arrangement of the shield are set so that, for example, a sufficient space is formed between the lower space 5 and the shield so that fog and cold air generated from the liquefied gas evaporator 1 can be temporarily stored. It ’s fine. For example, when there are other factory equipment or buildings in the vicinity of the liquefied gas evaporator 1, it is possible to block mist or cold air with the equipment or buildings, that is, Although the case where the said apparatus or building functions also as a shielding object with respect to fog and cold air is considered, in such a case, it is not necessary to provide a shielding body in the side in which the said apparatus or building exists. For example, when the liquefied gas evaporator 1 is installed in a place where the wind direction of the outside air is easily deflected in a specific direction, it is desirable to set the shape and arrangement of the shield in consideration of the wind direction. For example, a shield may be arranged leeward with respect to the liquefied gas evaporator 1. If it does so, the mist and cold which are easy to be flowed in the lee of the liquefied gas evaporator 1 can be blocked reliably.

  Note that, for example, devices installed around the liquefied gas evaporator 1, such as a measuring instrument and an operation valve provided for monitoring the state of the liquefied gas evaporator 1, may be provided outside the shield. By doing so, it is possible to prevent the operator from visually observing the measuring instrument and operating the valve from being disturbed by the presence of fog. In addition, it is possible to eliminate the trouble of opening a part of the shield or bypassing the shield because the worker enters the shield, and the workability can be improved.

  The present inventors performed the following experiment in order to confirm the fog diffusion preventing effect of the shield. As shown in FIG. 13, an enclosure 70 having a substantially square shape in plan view is erected from the reference plane 3, and four sides of the enclosure 70 are provided along the X-axis direction and the Y-axis direction, respectively. Inside the enclosure 70, three liquefied gas evaporators 1A, 1B, and 1C were placed side by side at a predetermined interval in the X-axis direction. The enclosure 70 is net-like, that is, air can move to the inside and outside of the enclosure 70 through the mesh, and only one side of the enclosure 70 located in the positive direction of the Y-axis direction is made of vinyl. The sheet 71 was covered. That is, the mesh is shielded by the sheet 71 so that air cannot be passed through the mesh and is blocked, and only one side of the enclosure 70 provided with the sheet 71 constitutes the shield 72. The height of the enclosure 70 from the reference plane 3 (the height in the Z-axis direction (vertical direction)) is 2 m, and the height from the liquefied gas evaporator 1B (the central portion of the lower space 5) in the Y-axis direction (positive direction). The distance was 4.55 m, and the distance from directly below the liquefied gas evaporator 1B in the Y-axis direction (negative direction) was 3.35 m.

Resistance thermometers were installed at multiple locations as thermometers. Specifically, as shown in FIGS. 13 and 14, the measurement position P1 _L , which is located directly below the liquefied gas evaporator 1B provided at the center and has a height of 0.5 m from the reference plane 3, Positioned directly below the gas evaporator 1B, the height from the reference plane 3 is 1.5 m (1.0 m higher in the vertical direction than the measurement position P1 _L ), the measurement position P1 _H and the measurement position P1 _{L in the} Y-axis direction The measurement position P2 _L is a position spaced by 3.0 m in the (positive direction) and the height from the reference plane 3 is 0.5 m, and 4 in the Y-axis direction (positive direction) from the measurement position P1 _L. .3 m in the position (near the inner surface of the sheet 71) at a measurement position P3 _L at a height of 0.5 m from the reference surface 3 and the measurement position P1 _{H in the} Y-axis direction (positive direction) 4.3m apart from the reference plane 3 at a distance of 3m 1.5m at a measurement position P3 _H, a Y-axis direction from the measuring position P1 _L spaced locations of 4.8m in (forward) (outer surface near the seat 71), the height from the reference plane 3 Is a position spaced by 4.8 m in the Y-axis direction (positive direction) from the measurement position P4 _L and the measurement position P1 _H, where the height from the reference plane 3 is 1.5 m. The measurement position P4 _H and the measurement position P1 _L are positions spaced by 3.1 m in the Y-axis direction (negative direction) (near the inner side on the side where the sheet 71 is not provided in the enclosure 70), and the reference plane 3 The measurement position P5 _L is 0.5 m from the measurement position P1 _H and the measurement position P1 _H is a position spaced by 3.1 m in the Y-axis direction (negative direction), and the height from the reference plane 3 is 1 a .5m measurement position P5 _H, from the measured position P1 _L Y A measurement position at a distance of 3.6 m in the direction (negative direction) (near the outside on the side where the sheet 71 is not provided in the enclosure 70) and having a height of 0.5 m from the reference plane 3 A total of 12 measurement positions P6 _H at a distance of 3.6 m in the Y-axis direction (negative direction) from P6 _L and measurement position P1 _H and having a height of 1.5 m from the reference plane 3 One RTD was installed at each location.

  In the configuration as described above, the two liquefied gas evaporators 1A, 1B out of the liquefied gas evaporators 1A, 1B, 1C are operated, and the liquefied gas is evaporated, and measurement is performed by each resistance temperature detector. . The experiment was conducted in the afternoon of July. The temperature of the outside air was 22 ° C. and the humidity was 68%. The result is shown in the graph of FIG.

As shown in FIG. 15, each measurement point inside the enclosure 70 and the shield 72 (area on the liquefied gas evaporator 1B side), that is, measurement positions P1 _H , P3 _H , P5 _H , P1 _L , P2 _L , P3 The measured temperature at _L and P5 _L is between −7.6 ° C. and 12.6 ° C., and is below the dew point temperature (15.8 ° C.) at a temperature of 22 ° C. and a humidity of 68%. It can be seen that fog is generated inside the body 72.

Next, when attention is paid to the situation where the height is 0.5 m on the side where the vinyl sheet 71 is not provided, that is, the measurement temperatures at the measurement positions P5 _L and P6 _L inside and outside the enclosure 70, the measurement temperatures are all dew points. It can be seen that fog is generated at around 0 ° C below the temperature. That is, it can be seen that a large amount of mist stays downward, and the mist and cold air permeate through the mesh of the enclosure 70 and flow outward. On the other hand, when focusing on the situation of the height of 0.5 m on the side of the shield 72 covered with the vinyl sheet 71, that is, the measurement temperatures at the measurement positions P3 _L and P4 _{L on} the inside and outside of the shield 72, the shield At the measurement position P3 _L inside 72, the measurement temperature is 3.4 ° C. below the dew point temperature, and fog is generated, whereas at the measurement position P4 _L outside the shield 72, the measurement temperature is above the dew point temperature. It can be seen that the temperature is 16.5 ° C. and the fog is eliminated. Similarly, paying attention to the measurement temperature at the measurement positions P3 _H and P4 _{H with} a height of 1.5 m on the shield 72 side, the measurement temperature is 10.0 ° C. at the inner measurement position P3 _H , and fog is generated. On the other hand, at the outer measurement position P4 _H , the measurement temperature is 16.4 ° C. and it can be seen that the fog is eliminated.

In addition, when the situation of the height of 1.5 m inside the enclosure 70 and the inside of the shield 72, that is, the measurement temperatures at the measurement positions P3 _H and P5 _H , is compared, it is 3.1 m away from just below the liquefied gas evaporator 1B. The measurement temperature at the measurement position P5 _H is 12.6 ° C., whereas the measurement temperature is 4.3 m from directly below the liquefied gas evaporator 1B, that is, the measurement is farther from the liquefied gas evaporator 1B than the measurement position P5 _H. The measurement temperature at the position P3 _H is 10.0 ° C., which is lower than the measurement position P5 _H. Therefore, in the shield 72 side, fog and cold air dammed by the shielding body 72, it is understood that staying up above the measurement position P3 _H.

  From the above, by providing the sheet 71 with the shield 71, fog and cold air generated by the operation of the liquefied gas evaporator 1 </ b> B are filled up inside the shield 72 and overflow from the shield 72. In this case, it is considered that the air is mixed with the relatively warm outside air and is heated to a dew point temperature or more by the outside air so that the fog is eliminated.

  The present invention can be applied to prevent diffusion of fog generated in a liquefied gas evaporator that evaporates liquefied gas such as LNG and LPG.

H1 Height of lower space H2 Height of shield L Distance between lower space and shield 1 Liquefied gas evaporator 2 Evaporator support 3 Reference surface 5 Lower space 10 Fog diffusion prevention structure 11 Shield 21 Heat transfer tube 31 Lower frame 35 Support legs

Claims (2)

A mist diffusion prevention structure that prevents mist from diffusing from the liquefied gas evaporator,
The liquefied gas evaporator is supported while being lifted from a reference plane,
Provided with a shield standing from the reference surface outside the lower space formed between the liquefied gas evaporator and the reference surface,
The shield is provided to face at least a part of the lower space;
It has a guided airflow formation mechanism that forms a guided airflow,
A fog diffusion preventing structure for a liquefied gas evaporator, characterized in that the atmosphere rising from the inside of the shield is drawn to the induced airflow. The wall is provided outside along the outer surface of the shield, and the guided airflow forming mechanism supplies gas to a gap between the shield and the wall. The mist diffusion prevention structure of the liquefied gas evaporator as described in 1.

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