JP6393028B2 - Underwater combustion type vaporizer - Google Patents

Description

  The technology disclosed herein relates to an underwater combustion type vaporizer.

  Patent Document 1 describes a submerged combustion vaporizer (Submerged Combustion Vaporizer) which is one of vaporizers for low-temperature liquefied gas such as liquefied natural gas. This underwater combustion type vaporizer is provided in a downcomer immersed in a water tank, and is an underwater combustion burner that burns air supplied from a blower and fuel supplied from a fuel supply source in a combustion chamber, and combustion of the burner A combustion section having a sparge pipe for jetting gas into the water, and a heat exchanger constituted by a heat transfer tube bundle including a number of heat transfer tubes immersed in the water tank, and jetted as bubbles into the water The low-temperature liquefied gas is vaporized by heating the low-temperature liquefied gas flowing through the heat transfer tube bundle while stirring the water in the water tank.

  Patent Document 2 also describes a similar underwater combustion type vaporizer. In particular, the underwater combustion type vaporizer described in Patent Document 2 uses a part of the vaporized low-temperature liquefied gas as fuel. It is configured to supply an underwater combustion burner. Thereby, the underwater combustion type vaporizer described in Patent Document 2 aims to reduce the operating cost of the equipment.

Japanese Utility Model Publication No. 5-75599 JP 2002-168149 A Japanese Examined Patent Publication No. 7-117212

  By the way, in recent years, from the viewpoint of the efficiency of transporting vaporized natural gas and the efficiency of new power generation methods such as combined cycle power generation, the pressure of the gas output from the underwater combustion type vaporizer must be set relatively high. Is considered.

  On the other hand, when a part of the vaporized gas is used as fuel for the underwater combustion burner as described in Patent Document 2, the high pressure gas cannot be supplied to the underwater combustion burner with a high pressure. Therefore, as described in Patent Document 3, for example, before supplying the pressure of the fuel gas to the burner, it is necessary to reduce the pressure to a predetermined pressure using a decompressor.

  However, as the pressure of the fuel gas is reduced as described above, the temperature of the fuel gas after passing through the pressure reducer is greatly reduced. For example, when the temperature of the gas output from the underwater combustion type vaporizer is about 0 ° C. and the pressure is about 5 MPa, the gas temperature is about −40 ° C. if the pressure is reduced to about 0.5 MPa. It will fall to.

  Further, in the configuration in which a part of the gas output from the underwater combustion type vaporizer is supplied to the underwater combustion burner, the distance from the decompressor to the underwater combustion burner is relatively close, so that the temperature of the gas remains low. It will be supplied to the combustion burner. In addition, the gas supplied to the underwater combustion burner is not limited to the gas output from the underwater combustion vaporizer in which the underwater combustion burner is installed, but may be the gas output from another vaporizer in the gas manufacturing plant. Even in such a case, the temperature after the gas passed through the pressure reducer is not sufficiently increased by the environmental temperature until the gas is supplied to the underwater combustion burner.

  As described above, in the configuration in which a part of the gas output from the underwater combustion type vaporizer is supplied to the underwater combustion burner, as a result of adjusting the pressure of the fuel gas, the temperature of the fuel gas is greatly reduced. . It is not preferable to supply such a low-temperature gas as a fuel to the underwater combustion burner. In addition, when the underwater combustion type vaporizer that ignites the underwater combustion burner is started, it is conceivable that the low-temperature fuel gas reduces the ignitability of the burner.

  The technology disclosed herein has been made in view of such a point, and the object is to adjust the pressure and temperature of the fuel gas supplied to the underwater combustion burner of the underwater combustion type vaporizer with a simple configuration. Is to make it possible.

The technology disclosed herein includes a water tank for storing water, an underwater combustion burner, and a combustion unit configured to eject the combustion gas of the underwater combustion burner into the water tank, and immersion in the water tank. A heat exchanger configured to output a gas having a predetermined pressure after vaporizing a low-temperature liquefied gas passing through the heat transfer tube, and a gas output from the heat exchanger a portion of a fuel supply mechanism configured to supply a fuel to the submerged combustion burners, Ru engages the submerged combustion type vaporizer equipped with.

The fuel supply mechanism includes a decompressor configured to depressurize the gas at the predetermined pressure, and a riser configured to increase the temperature of the low-temperature gas after passing through the decompressor before supplying the underwater combustion burner. The temperature raising unit is constituted by a heat transfer tube that is immersed in the water tank and through which the low-temperature gas flows, and is vaporized in another vaporizer different from the underwater combustion vaporizer. The gas supplied through the supply port is supplied by the decompressor of the underwater combustion type vaporizer when the underwater combustion type vaporizer is started. together is reduced, after being heated by the heating portion of the submerged combustion type vaporizer is supplied to the submerged combustion burners of the submerged combustion type vaporizer.

  According to this structure, the temperature of the water in a water tank raises with the underwater combustion burner of a combustion part operating, and the combustion gas ejecting in a water tank. The low-temperature liquefied gas passing through the heat transfer tube of the heat exchanger is vaporized by exchanging heat with the water in the water tank, and the vaporized gas is output from the underwater combustion type vaporizer. The pressure of the gas to be output is set to a predetermined pressure. Here, the low-temperature liquefied gas may be, for example, liquefied natural gas, but is not limited thereto.

  Part of the gas output from the underwater combustion type vaporizer is supplied as fuel gas to the underwater combustion burner by the fuel supply mechanism. Here, the gas supplied as fuel gas to the underwater combustion burner by the fuel supply mechanism may not be the gas itself output from the underwater combustion type vaporizer in which the underwater combustion burner is installed. That is, the gas which the other underwater combustion type vaporizer and the vaporizer of another structure output may be included. In addition, when the underwater combustion type vaporizer is started, the gas output from the underwater combustion type vaporizer is substantially absent, so the gas output from other underwater combustion type vaporizers and vaporizers of other configurations, What is necessary is just to supply an underwater combustion burner.

  The fuel supply mechanism includes a decompressor configured to decompress a gas having a predetermined pressure, and a temperature raising unit configured to increase the temperature of the low-temperature gas after passing through the decompressor before supplying the underwater combustion burner. And have. In the configuration in which a part of the gas output from the underwater combustion vaporizer is supplied to the underwater combustion burner, the distance from the decompressor to the underwater combustion burner is relatively short, but the fuel supply mechanism is reduced by the passage of the decompressor. It is possible to supply the fuel gas to the underwater combustion burner after sufficiently raising the temperature of the fuel gas. That is, a fuel gas having a predetermined temperature and a predetermined pressure is supplied to the underwater combustion burner. In this way, low temperature fuel gas is not supplied to the underwater combustion burner, so that the ignitability is improved, for example, when the underwater combustion burner is ignited.

  The temperature raising part is constituted by a heat transfer tube immersed in the water tank. As a result, the low-temperature gas after passing through the decompressor is heated by exchanging heat with the water in the water tank while flowing in the heat transfer tube of the temperature raising section. By using the water tank that constitutes the underwater combustion type vaporizer, there is no need to separately secure a heat source for raising the temperature of the low-temperature gas, and it is also necessary to separately secure the installation space necessary for the temperature raising part. Disappear. In this way, the facility can be simplified.

  The water temperature in the water tank of the underwater combustion vaporizer is sufficiently high when the underwater combustion vaporizer is in operation, and the heat capacity is sufficiently large even when the underwater combustion vaporizer is stopped. It does not drop significantly. Moreover, in the said structure, since the temperature of the low-temperature gas after passing a pressure reduction device is heated, thermal efficiency becomes high. The water temperature in the water tank is not required to be so high. Therefore, the temperature of the fuel gas supplied to the underwater combustion burner when the underwater combustion type vaporizer is started up can be increased to a predetermined temperature by the temperature raising unit. In addition, you may employ | adopt the structure which maintains a water temperature at predetermined temperature at the time of a stop of an underwater combustion type vaporizer by attaching the heater which heats the water in a water tank, or supplying steam.

  The combustion section further includes a sparge pipe that is disposed in a predetermined region in the water tank and ejects the combustion gas as bubbles in the water tank, and the heat exchanger includes a plurality of the heat transfer tubes, The heat transfer tube bundle is configured to be folded in multiple stages in the vertical direction, and is arranged in parallel in the region where the sparge pipe is disposed, and the heat transfer tube of the temperature raising unit is the heat exchanger It is good also as arrange | positioning with the container in the position which overlaps with respect to the arrangement | positioning area | region of the said sparge pipe in the said water tank.

  In an underwater combustion vaporizer, a sparge pipe that ejects combustion gas as bubbles increases the heat exchange efficiency by generating a rising water flow around the heat exchanger tube bundle of the heat exchanger, and the vaporization of the low-temperature liquefied gas in the heat exchanger It becomes advantageous for promotion. In the above-described configuration, the heat transfer tube of the temperature raising unit that raises the temperature of the fuel gas is disposed at a position overlapping the sparge pipe arrangement region in the water tank together with the heat exchanger. The temperature rise of the fuel gas in the fuel cell is also promoted.

  The heat transfer tube of the temperature raising unit may be provided integrally with the heat exchanger.

  Providing a temperature raising part for the fuel gas integrally with the heat exchanger installed in the water tank is advantageous in improving space efficiency.

  The decompressor may be disposed in the vicinity of the water tank. Although the temperature of the gas after passing through the pressure reducer decreases, the heat transfer tube connected to the pressure reducer is immediately introduced into the water tank by disposing the pressure reducer in the vicinity of the water tank. Is possible. This makes the area of the piping through which the low temperature gas flows as short as possible. As a result, the number of piping configurations that need to be low-temperature specifications can be reduced as much as possible to simplify the equipment.

  As described above, according to the underwater combustion type vaporizer, the fuel supply mechanism that supplies part of the gas output from the heat exchanger to the underwater combustion burner as the fuel gas reduces the gas at a predetermined pressure. The pressure and temperature of the fuel gas can be adjusted with a simple configuration by including the configured pressure reducer and the temperature raising unit configured by the heat transfer tube immersed in the water tank.

It is the schematic which shows the structure of an underwater combustion type vaporizer. It is a front view which shows the structure of a heat exchanger. It is a top view which shows the structure of a heat exchanger.

  Hereinafter, an embodiment of an underwater combustion type vaporizer will be described based on the drawings. In addition, the following description of preferable embodiment is an illustration.

  FIG. 1 conceptually shows the configuration of the underwater combustion type vaporizer 1. The underwater combustion type vaporizer 1 is a liquefied natural gas (LNG) vaporizer, and is installed, for example, in a gas manufacturing factory. The underwater combustion type vaporizer 1 includes a water tank 11 for storing water, a heat exchanger 3 that is immersed in the water tank 11 and is formed by bending a large number of heat transfer tubes serving as LNG flow paths in multiple stages. The fuel gas supplied through the fuel supply mechanism 4 to be described later and the air supplied through the blower 14 are provided below the water surface. An underwater combustion burner 2 to be combusted at a position, and a sparge pipe 15 which is disposed at the bottom of the water tank 11 and communicates with the lower end of the downcomer 13 and has a plurality of small holes through which the combustion gas of the underwater combustion burner 2 is ejected. And a stack 16 that is disposed in the upper part of the water tank 11 and exhausts combustion exhaust gas. The combustion unit 5 is configured including the underwater combustion burner 2, the downcomer 13, the sparge pipe 15 and the like.

  The underwater combustion type vaporizer 1 passes through the heat exchanger 3 while stirring the water in the water tank 11 by ejecting the combustion gas of the underwater combustion burner 2 as bubbles into the water tank 11 through the small holes of the sparge pipe 15. LNG to be heated. In this way, LNG is vaporized into natural gas (NG), which is sent out from the outlet of the heat exchanger 3. The underwater combustion type vaporizer 1 is characterized by extremely high thermal efficiency because it is possible to stir the water in the water tank 11 by ejecting the combustion gas as bubbles into the water tank 11.

  2 and 3 are a front view and a plan view of the heat exchanger 3 disposed in the water tank 11. In the following description, for the sake of convenience, the horizontal direction in FIG. 2 is the X direction, the vertical direction in FIG. 2 is the Z direction, the horizontal direction in FIG. 3 is the X direction, and the vertical direction in FIG. To do.

  The heat exchanger 3 collects heat transfer tube bundles 32 including a plurality of heat transfer tubes 31, an inlet header tank 33 that distributes LNG to each heat transfer tube 31, and NG from each heat transfer tube 31. The outlet side header tank 34 is provided. The heat transfer tube bundle 32, the inlet header tank 33 and the outlet header tank 34 are supported by a frame 35 installed at the bottom in the water tank 11.

  The entry-side header tank 33 is disposed so as to extend in the Y direction at one end portion in the X direction at the lower portion of the frame 35 (the left end portion in FIG. 2 and FIG. 3). Although not shown in FIGS. 2 and 3, an LNG supply pipe is connected to the inlet header tank 33.

  The outlet header tank 34 is disposed so as to extend in the Y direction at one end portion in the X direction at the upper portion of the frame 35 (the left end portion in FIG. 2 and FIG. 3). The outlet header tank 34 is disposed above the inlet header tank 33. Thus, in the water tank 11, LNG flows from the bottom to the top in the heat transfer tube 31 of the heat exchanger 3. Although not shown in FIGS. 2 and 3, an NG discharge pipe is connected to the outlet header tank 34.

  In the illustrated example, the heat transfer tube 31 is composed of two heat transfer tubes 31, 31, and the heat transfer tube bundle 32 is provided with a predetermined interval in the Y direction as shown in FIG. 3. A plurality of heat transfer tubes 31 arranged side by side are included. Each heat transfer tube 31 has one end connected to the upper part of the inlet header tank 33 and the other end connected to the lower part of the outlet header tank 34, and its intermediate part is multistage in the Z direction. It is configured to be zigzag folded in the X direction. The heat exchanger 3 including the heat transfer tube bundle 32 is made of, for example, stainless steel. In addition, although illustration is abbreviate | omitted, in each heat-transfer tube 31, a helical heat-transfer promoter may be inserted in the inside.

  A plurality of sparge pipes 15 are disposed below the frame 35 of the heat exchanger 3. Each sparge pipe 15 extends in the Y direction and is arranged in parallel at a predetermined interval in the X direction, like the inlet and outlet header tanks 33 and 34. The heat transfer tube bundle 32 of the heat exchanger 3 is disposed in a position that overlaps the region where the sparge pipe 15 is disposed in the water tank 11. As a result, bubbles of the combustion gas ejected from the sparge pipe 15 cause an upward water flow that passes between the heat transfer tube bundles 32 and moves upward from the bottom. This rising water flow improves the heat exchange efficiency in the heat exchanger 3.

  Here, from the viewpoint of transport efficiency of NG and the efficiency of a new power generation method such as combined cycle power generation, the pressure of NG output from the underwater combustion type vaporizer 1 is set to be relatively high. Moreover, the temperature of NG which the underwater combustion type vaporizer 1 outputs is about 0-30 degreeC.

  Then, in this underwater combustion type vaporizer 1, a part of NG output from the heat exchanger 3 is supplied as fuel gas to the underwater combustion burner 2 as shown by the one-dot chain line arrow in FIG. It is configured. Here, the fuel gas supplied to the underwater combustion burner 2 is not limited to NG itself output from the underwater combustion type vaporizer 1 in which the underwater combustion burner 2 is installed, but is installed in a gas manufacturing factory. NG output from another underwater combustion type vaporizer or a vaporizer having another configuration installed in the factory may be included. At the time when the underwater combustion burner 2 is ignited so as to start the underwater combustion type vaporizer 1, the NG output from the underwater combustion type vaporizer 1 is substantially absent. Therefore, at least the fuel gas from another vaporizer is supplied to the underwater combustion burner 2 when the underwater combustion type vaporizer 1 is started.

  As shown in FIG. 1, a fuel supply mechanism 4 that supplies fuel gas to the underwater combustion burner 2 includes a decompressor 41 that reduces the pressure of the fuel gas (that is, NG), and the temperature of the fuel gas that has become low after decompression. The temperature raising part 42 to be raised is provided. Thereby, the fuel supply mechanism 4 adjusts the temperature and pressure of the fuel gas supplied to the underwater combustion burner 2 to predetermined temperatures and pressures, respectively.

  The decompressor 41 decompresses NG having a predetermined pressure output from the heat exchanger 3. The decompressor 41 may depressurize NG from, for example, 5 MPa to about 0.5 MPa. For example, the pressure reducer 41 may be configured by pressure reducing valves arranged in one or more stages. As conceptually shown in FIG. 1, the decompressor 41 is disposed in the vicinity of the water tank 11, in the illustrated example, immediately above the lid that closes the upper surface opening of the water tank 11. As a result, it is possible to immediately introduce the pipe of the temperature raising unit 42 connected to the decompressor 41 and through which NG after decompression flows, into the water tank 11.

  The temperature raising part 42 is a part that raises the temperature of the NG that has become low temperature by passing through the pressure reducer 41, and this temperature raising part 42 is configured by a heat transfer tube 421 that is immersed in the water tank 11. . As shown in FIGS. 2 and 3, the heat transfer tube 421 is provided integrally with the heat exchanger 3. Specifically, the temperature raising unit 42 includes a heat transfer tube bundle 422 including a plurality of heat transfer tubes 421, an inlet header tank 423, and an outlet header tank 424.

  The inlet-side header tank 423 is a header tank that distributes the low-temperature fuel gas after passing through the pressure reducer 41 to each heat transfer tube 421, and the other end portion in the X direction (see FIG. 2) below the frame 35 of the heat exchanger 3. 3 at the right end of the paper surface in FIG. Therefore, the inlet header tank 423 of the temperature raising unit 42 is disposed on the opposite side of the heat transfer tube bundle 32 with respect to the inlet header tank 33 of the heat exchanger 3. Although not shown in FIGS. 2 and 3, the inlet header tank 423 communicates with a pipe connected to the pressure reducer 41 (see FIG. 1. Note that in FIG. 1, the temperature raising unit 42 is conceptually shown. (Because it is drawn, the inlet and outlet header tanks 423 and 424 are not clearly shown).

  The outlet header tank 424 is a header tank that collects fuel gas that has been heated by passing through each heat transfer tube 421, and is disposed at the other end in the X direction at the upper part of the frame 35 of the heat exchanger 3. Yes. Therefore, the outlet header tank 424 is disposed above the inlet header tank 423 and on the opposite side of the heat exchanger tube bundle 32 with respect to the outlet header tank 34 of the heat exchanger 3. . Thus, the fuel gas also flows from the bottom to the top in the heat transfer tube 421 in the water tank 11 as in the case of LNG. The outlet header tank 424 is connected to the underwater combustion burner 2 (see FIG. 1).

  The heat transfer tube bundle 422 of the temperature raising unit 42 is configured in the same manner as the heat transfer tube bundle 32 of the heat exchanger 3. That is, in the heat transfer tube bundle 422, in the example of FIG. 2, one end of the heat transfer tube 421 configured as a pair is connected to the upper portion of the inlet header tank 423, and the other end of each heat transfer tube 421 is extended. It is connected to the lower part of the side header tank 424, and its middle part is configured to be zigzag folded in the X direction so as to be multistage in the Z direction. As shown in FIG. 3, the heat transfer tube bundle 422 of the temperature raising unit 42 is also on one side in the Y direction (the lower side in the drawing in FIG. 3) with respect to the heat transfer tube bundle 32 of the heat exchanger 3 arranged in parallel in the Y direction. It is arranged. The arrangement position of the heat transfer tube 421 in the temperature raising unit 42 is not limited to the illustrated example, and can be set as appropriate. For example, the heat transfer tube 421 of the temperature raising unit 42 may be disposed on the other side in the Y direction (upper side in the drawing in FIG. 3) with respect to the heat transfer tube bundle 32 of the heat exchanger 3, or the heat transfer of the heat exchanger 3. The heat transfer tube 421 of the temperature raising unit 42 may be disposed at an intermediate position in the Y direction in the tube bundle 32.

  Since the number of heat transfer tubes 421 in the temperature raising section 42 is relatively small, it can be provided integrally with the heat exchanger 3 and the space efficiency is improved. Similarly to the heat exchanger 3, the temperature raising unit 42 including the heat transfer tube bundle 422 may be made of, for example, stainless steel.

  Further, the heat transfer tube 421 of the temperature raising unit 42 may be configured by inserting a heat transfer promoting body similar to the heat transfer promoting body inserted into the heat transfer tube 31 of the heat exchanger 3 therein. Further, the heat transfer tube 421 of the temperature raising unit 42 may adopt a configuration different from the heat transfer tube 31 of the heat exchanger 3 because LNG does not flow but only NG flows.

  In the underwater combustion type vaporizer 1 having the above configuration, during operation, air is supplied to the underwater combustion burner 2 through the blower 14 and fuel gas is supplied through the fuel supply mechanism 4. Then, the combustion gas of the underwater combustion burner 2 is ejected as bubbles into the water tank 11 through a large number of small holes formed in the sparge pipe 15.

  The flow including the bubbles flows upward between the heat transfer tube bundles 32 of the heat exchanger 3. On the other hand, in the heat exchanger 3, LNG flows into each heat transfer tube 31 through the inlet header tank 33, and LNG flows through the heat transfer tubes 31 configured in multiple stages. During this time, LNG is heated and vaporized. NG vaporized in each heat transfer tube 31 is collected in the outlet header tank 34 and then output from the underwater combustion vaporizer 1. The output NG pressure is set to a predetermined high pressure, and the temperature becomes a predetermined temperature (for example, 0 to 30 ° C.).

  A part of NG output from the underwater combustion type vaporizer 1 is supplied as fuel gas to the underwater combustion burner 2 through the fuel supply mechanism 4 as described above. That is, NG first depressurizes to a predetermined pressure suitable for supply to the underwater combustion burner 2 by passing through the decompressor 41. The temperature of NG after decompression is, for example, −40 ° C.

  The low-temperature NG after depressurization is then introduced into the water tank 11 through the piping of the temperature raising unit 42 and flows into the heat transfer tubes 421 from the inlet header tank 423. Similarly to the heat transfer tube 31 of the heat exchanger 3, the heat transfer tube 421 of the temperature raising unit 42 is exposed to a gas-liquid two-phase flow containing bubbles ejected from the sparge pipe 15. The low-temperature NG flowing through the heat transfer tube 421 of the temperature raising unit 42 is heated. Then, NG that has reached a predetermined temperature (for example, 0 ° C. or higher) is collected in the outlet header tank 424 and then supplied to the underwater combustion burner 2.

  Thus, in the underwater combustion type vaporizer 1 having the above-described configuration, the fuel gas adjusted to a predetermined temperature and pressure can be supplied to the underwater combustion burner 2. Thus, in the configuration in which a part of NG output from the underwater combustion type vaporizer 1 is supplied to the underwater combustion burner 2, the distance between the decompressor 41 and the underwater combustion burner 2 is relatively short. Although the low temperature NG after passing through 41 does not sufficiently increase at the environmental temperature, the temperature of the fuel gas supplied to the underwater combustion burner 2 can be efficiently increased by using the water temperature in the water tank 11. It becomes possible.

  In the above configuration, since the temperature of the NG that has become low after decompression is raised using the water tank 11 of the underwater combustion vaporizer 1, it is not necessary to prepare a separate heat source for raising the temperature of the NG. In addition, it is not necessary to separately secure an installation space for the temperature raising unit 42 that raises the temperature of NG. This is advantageous in simplifying the equipment.

  Further, as described above, while the underwater combustion type vaporizer 1 is in operation, the temperature of the water in the water tank 11 is sufficiently high, so that it is possible to sufficiently raise the temperature of NG. Further, even when the underwater combustion type vaporizer 1 is stopped, the water temperature in the water tank 11 is not significantly lowered due to the relatively large heat capacity. Further, since the temperature of the NG that has become low after decompression is raised, the thermal efficiency is increased, and the water temperature in the water tank 11 required to raise the temperature of NG to a predetermined temperature is not required to be so high. That is, even when the underwater combustion type vaporizer 1 is started, the water tank 11 can be used as a heat source for raising the temperature of NG.

  On the other hand, since the inside of the downcomer 13 in which the underwater combustion burner 2 is arrange | positioned is installed in the water tank 11, it is in a state with very high humidity. For this reason, if NG of about minus several tens of degrees Celsius is supplied to the burner 2 when the underwater combustion burner 2 is ignited, moisture in the air freezes, so that the ignitability of the underwater combustion burner 2 may be reduced. .

  Therefore, when the stopped underwater combustion type vaporizer 1 is started, the underwater combustion burner 2 is heated by raising the temperature of the NG that has been reduced to a predetermined pressure by the pressure reducer 41 to about 0 ° C. Therefore, it is possible to reliably ignite the underwater combustion burner 2 while avoiding a decrease in the ignitability. When the underwater combustion type vaporizer 1 is started, NG vaporized in another vaporizer in the gas manufacturing plant is supplied as fuel gas.

  While the apparatus is stopped, in order to reliably maintain the water temperature in the water tank 11 at a predetermined temperature, although not shown, a heater for heating water is separately provided or steam is used. May be.

  Further, as described above, since the heat transfer tube 421 of the temperature raising unit 42 is provided integrally with the heat transfer tube bundle 32 of the heat exchanger 3, the low-temperature NG is utilized by utilizing the bubbles ejected from the sparge pipe 15. It is possible to effectively raise the temperature. In particular, this is because the NG pressure output from the underwater combustion type vaporizer 1 is set high, while the decompressor 41 greatly reduces the NG pressure, resulting in a significant decrease in the NG temperature. Before the supply to the underwater combustion burner 2, the temperature of the NG can be sufficiently increased with a simple configuration.

  Further, as shown in FIG. 1, the decompressor 41 is disposed in the vicinity of the water tank 11, and thereby, the piping of the temperature raising unit 42 connected to the decompressor 41 is immediately introduced into the water tank 11. It becomes possible. This has the advantage that the portion of the pipe where the low-temperature NG after passing through the pressure reducer 41 flows is as short as possible, and the length of the pipe portion requiring low-temperature specifications is shortened. This contributes to simplification of equipment.

  In the above configuration, the heat transfer tube bundle 32 is sandwiched between the inlet header tank 423 and the outlet header tank 424 of the temperature raising unit 42 with respect to the inlet header tank 33 and the outlet header tank 34 of the heat exchanger 3. However, the arrangement positions of the inlet header tank 423 and the outlet header tank 424 are not particularly limited, and the inlet header tank 33 and the outlet header tank of the heat exchanger 3 are not particularly limited. It may be arranged on the same side as 34.

  Further, the heat transfer pipe 421 of the temperature raising unit 42 is formed by replacing a part of the heat transfer pipe 31 arranged to constitute the heat transfer pipe bundle 32 of the heat exchanger 3 with the inlet header tank 33 and the outlet header tank of the heat exchanger 3. Instead of being connected to 34, it may be configured by connecting to the inlet header tank 423 and the outlet header tank 424 of the temperature raising unit 42. Such a configuration makes it possible to configure the underwater combustion type vaporizer 1 having the above configuration by modifying an existing underwater combustion type vaporizer.

  Further, the heat transfer tube bundle 422 of the temperature raising unit 42 only needs to be immersed in at least the water tank 11.

DESCRIPTION OF SYMBOLS 1 Underwater combustion type vaporizer 11 Water tank 15 Sparge pipe 2 Underwater combustion burner 3 Heat exchanger 31 Heat transfer tube 32 Heat transfer tube bundle 4 Fuel supply mechanism 41 Decompressor 42 Temperature rising part 421 Heat transfer tube 5 Combustion part

Claims (4)

A water tank for storing water;
A combustion section having an underwater combustion burner and configured to eject the combustion gas of the underwater combustion burner into the water tank;
A heat exchanger configured to output a gas having a predetermined pressure after vaporizing the low-temperature liquefied gas passing through the heat transfer tube, and having a heat transfer tube immersed in the water tank;
A fuel supply mechanism configured to supply a part of the gas output from the heat exchanger as fuel to the underwater combustion burner, and an underwater combustion type vaporizer comprising:
The fuel supply mechanism includes a decompressor configured to depressurize the gas at the predetermined pressure, and a riser configured to increase the temperature of the low-temperature gas after passing through the decompressor before supplying the underwater combustion burner. And has a warm part,
The temperature raising unit is arranged by immersion in the water tank and is constituted by a heat transfer tube through which the low-temperature gas flows,
The gas vaporized in another vaporizer different from the underwater combustion vaporizer has a supply port to be supplied to the underwater combustion vaporizer,
When starting up the underwater combustion type vaporizer , the gas supplied through the supply port is depressurized by the decompressor of the underwater combustion type vaporizer and also heated by the temperature raising unit of the underwater combustion type vaporizer. Then, the underwater combustion type vaporizer supplied to the underwater combustion burner of the underwater combustion type vaporizer. The underwater combustion vaporizer according to claim 1,
The combustion unit further includes a sparge pipe disposed in a predetermined region in the water tank and ejecting the combustion gas as bubbles in the water tank,
The heat exchanger includes a plurality of heat transfer tubes that are folded back so as to be multi-staged in the vertical direction, and have heat transfer tube bundles that are arranged in parallel within the region where the sparge pipe is disposed. ,
The heat transfer tube of the temperature raising part is an underwater combustion type vaporizer arranged together with the heat exchanger at a position overlapping with an arrangement region of the sparge pipe in the water tank. The underwater combustion vaporizer according to claim 2,
The heat transfer tube of the temperature raising unit is an underwater combustion type vaporizer provided integrally with the heat exchanger. In the underwater combustion type vaporizer of any one of Claims 1-3,
The decompressor is an underwater combustion type vaporizer disposed in the vicinity of the water tank.

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