JPH0648146B2 - Double pipe type open rack type vaporizer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an open rack type vaporizer for vaporizing liquefied natural gas with a heat medium such as seawater, wherein a heat exchange pipe has a double pipe structure, and for example, The liquefied natural gas is supplied from the upper end to the inner pipe, and the vaporized gas is led out by a U-shaped flow from the small hole in the outer periphery of the lower part to the upper part of the outer pipe through the passage between the outer pipe and the inner pipe. The present invention relates to a double-tube open rack type vaporizer that aims to prevent air pollution, reduce icing, reduce seawater volume, and stabilize gas flow.

BACKGROUND ART As an open rack type vaporizer for vaporizing liquefied natural gas (hereinafter referred to as LNG) using a heat medium such as seawater, a single pipe open rack type vaporizer has been the mainstream conventionally.

As shown in FIG. 6, the single pipe open rack type vaporizer is a heat exchange panel in which a large number of single heat exchange pipes are connected in parallel.
LNG is supplied from the lower header tank (2) provided at the lower end of (1), and troughs are placed on both sides of the upper part of the heat exchange panel (1).
By the seawater sprinkled from (3), as the LNG rises in the pipe, it is heated and vaporized by the seawater that is the heat medium outside the pipe,
Upper header tank installed on top of heat exchange panel (1)
The natural gas (hereinafter referred to as NG) is supplied to the outside from (4).

The single-tube open rack type vaporizer has a simple structure and is easy to manufacture as described above, but it does not use seawater as a heat medium and cryogenic temperatures.
Since heat is directly exchanged with LNG via the single pipe wall of the heat exchange panel (1), there is a problem that ice formation occurs outside the pipe, that is, on the surface of the heat exchange panel (1), and increases.

More specifically, if the amount of water spray supplied to each heat exchange tube of the heat exchange panel (1) is uneven, the ice accretion height generated on the outer surface of the tube will be unbalanced. As the LNG flow rate increases, the amount of ice imbalance increases.

As a result, the temperature of each heat exchange tube itself becomes non-uniform, the amount of shrinkage of each heat exchange tube becomes different, and the thermal stress increases, so that the capability of the vaporizer is greatly restricted.

Therefore, conventionally, in order to prevent the imbalance of ice accretion on the surface of the heat exchange panel (1), means such as making the amount of water sprayed to each heat exchange tube uniform and relaxing thermal stress have been proposed. However, the fundamental drawback of the single pipe open rack type vaporizer could not be resolved.

As a method of solving such a problem, it is conceivable that the heat exchange tube is a double tube type and indirectly heats LNG, but the heat transfer efficiency is poor and the temperature of NG is lowered by the cryogenic LNG to supply the gas at normal temperature. In order to do so, there are many problems such as the need to heat the low-temperature gas that has left the vaporizer. Selection of the header tank and trough locations, and the use of the inner and outer pipe passages in consideration of heat transfer efficiency. For example, the optimum configuration as an LNG vaporizer has not been proposed.

An object of the present invention is to reduce the ice adhesion to the surface of the heat exchange panel, which has been a problem in the conventional single-tube open rack type vaporizer, and therefore, the heat exchange tube does not have a double-tube structure and does not have a lower header tank. The purpose of the present invention is to provide a vaporizer that does not have it, and to provide a double-tube open rack vaporizer that prevents flow hunting, reduces ice accretion, reduces the amount of seawater, and stabilizes the gas flow.

SUMMARY OF THE INVENTION The present invention forms a heat exchange panel by arranging a large number of heat exchange tubes having a double pipe structure, and arranges a liquefied gas inlet header tank and a vaporized gas outlet header tank at the upper or lower part of the heat exchange panel, A sprinkling trough is arranged on the upper part of the panel, and liquefied gas is introduced from one end of the inner pipe so that gas and liquid can be mixed in the outer pipe through a small hole provided outside the closed other end of the inner pipe. A double-tube open rack vaporizer characterized in that vaporized gas is led out through an annular passage between an outer pipe and an inner pipe.

The double-tube open rack type vaporizer according to the present invention may have various configurations. To explain one example in detail, a plurality of double-tube heat exchange tubes are connected to form a heat exchange panel, and the upper part of the panel is formed. A sprinkling trough is installed to enable heating, and liquefied gas is introduced into the inner pipe from the inlet header tank provided on the upper or lower end side of the heat exchange pipe, and the other end closed at the position opposite to the inlet header tank. The fluid that allows gas-liquid mixing in the outer tube through the small hole provided on the outer circumference of the inner tube on the side of the inner tube moves upward or downward in the annular passage between the outer tube and the inner tube, and the water spray on the outer surface of the outer tube and the liquefied gas inside the inner tube and heat. It is not replaceable, and the vaporized gas whose vaporization temperature has been raised can be discharged from the outlet header tank connected to the outer pipe on the inlet header tank side.

In addition, an inner pipe shorter than the outer pipe was coaxially inserted into the outer pipe having one end closed and an outlet header tank provided at the other end so that the open end faced the outer pipe closed end, and the inner header tank was connected. A heat exchange panel is formed by arranging a number of double-walled heat exchange tubes arranged at a position where the closed end of the tube is separated from the outlet header tank by a required distance, and the header tank is erected at the top or bottom. Then, a sprinkling trough is placed on the upper part of the panel to enable heating, and liquefied gas is introduced into the inner pipe from the inlet header tank connected to the closed end side of the inner pipe, and it is provided on the outer periphery on the closed other end of the inner pipe. It is possible to mix gas and liquid in the outer tube through the small hole, and to exchange heat between the fluid moving up and down in the annular passage between the outer tube and the inner tube, the water spray on the outer surface of the outer tube and the liquefied gas in the inner tube, Is it an outlet header tank connected to the end of the outer pipe? It is configured to derive the vaporized gas.

Structure of the Invention This invention is an LN such as a conventional open rack type vaporizer.
As a result of various studies aimed at an open rack type vaporizer with a double pipe structure that reduces ice accumulation on the G inlet header tank side, a heat exchange panel was formed by connecting multiple heat exchange pipes with a double pipe structure. , Liquefied gas is introduced from one end of the inner pipe, gas and liquid can be mixed in the outer pipe through a small hole provided on the outer circumference of the closed end of the inner pipe, and the vaporized gas is annular between the outer pipe and the inner pipe. While outflowing through the passage, seawater → outer pipe → NG → inner pipe → LN
With the configuration that heats up with G, it is possible to reduce the amount of seawater by reducing ice inevitable with conventional equipment, reduce the amount of pumping pump used, and prevent flow and calorie hunting. The inventors have found that a stable vaporizer can be obtained, and completed the present invention.

In the present invention, the double pipe structure allows LNG to flow from one end of the inner pipe, and the LN
If G and NG are mixed and passed through the annular passage between the outer pipe and the inner pipe and NG can be derived, the upper end of the inner pipe projects from the outer pipe. Can be adopted in any configuration, such as

Further, as the outer tube, a finned tube having an outer peripheral surface provided with a star fin can be used. Further, both the inner pipe and the outer pipe may be provided with recesses or projections on their inner surfaces to increase the heat transfer area.

The small holes to be provided in the outer periphery on the closed end side of the inner pipe, etc. are appropriately selected in consideration of various conditions such as inner and outer pipe dimensions and heat exchange efficiency, and the installation range, hole arrangement and size, etc. By selecting the position, size, and number of the small holes, the rise of the NG temperature in the outer pipe can be arbitrarily set, and the amount of ice accretion generated on the outer surface of the outer pipe due to the decrease in the NG temperature can be suppressed.

In the present invention, when the LNG inlet side is provided at the end of the double pipe in the header tank, the NG outlet side may be at any position as long as it is the LNG inlet side.

Further, when the NG outlet header tank is provided at the upper end of the outer pipe, the NG cooled by the LNG immediately after the inflow is sufficiently heated, so the LNG inlet header tank is arranged so as to be separated from the NG outlet by a required distance. However, it may be located at any position above the center of the heat exchange panel.

In the present invention, the sprinkling trough may have any configuration as long as it can sprinkle seawater from the upper part of the heat exchange panel to the outer pipe so that the seawater flows down to the outer peripheral surface, but it is arranged so as not to spray at least the LNG inlet header tank It is necessary to arrange them according to the position of each header tank.

In the present invention, it is desirable to subject the LNG inlet header tank and the connecting pipe to the inner pipe to a heat insulating treatment, and using a known heat insulating material such as Bakelite or stainless steel, the double pipe structure described above, the position of the inlet header tank, It is advisable to appropriately select the coating position, the range, the amount thereof, etc. according to the conditions such as the NG exit position.

Disclosure of the Invention Based on the Drawings FIG. 1 to FIG. 3 are longitudinal explanatory views showing the configuration of a double pipe type open rack type vaporizer according to the present invention.

FIGS. 4 and 5 are graphs showing the temperatures of seawater, LNG, and NG by the difference in height position of the heat exchange panel.

Structure 1 The double-tube open rack type vaporizer according to the present invention shown in FIG. 1 has a large number of double-tube heat exchange tubes arranged in parallel to form a heat exchange panel, which are vertically arranged. An LNG inlet header tank and an NG outlet header tank are provided on the upper part of the.

Each heat exchange tube has the required length and inner diameter, and the inner tube (11) is inserted into the outer tube (10) whose lower end is closed, but the inner tube (11) is the outer tube (10).
The closed bottom is desired on the inner bottom, and small holes (11a) of the required inner diameter are provided in the lower part of the inner pipe (11) by selecting the installation range, spacing, and number optimally. 11) The upper end is connected to the LNG inlet header tank (12) so that LNG can be introduced and flowed down,
In addition, the header tank (12) is configured to close the upper end of the outer pipe (10).

The NG outlet header tank (14) is arranged via an NG outlet pipe (13) connected to the outer pipe (10) below the LNG inlet header tank (12).

Also, on the outer surface of each outer tube (10) that constitutes the heat exchange panel,
Water sprinkling troughs (15) (1) arranged below the NG outlet pipe (13) side and below the LNG inlet header tank (12) on the opposite side.
Overflow from 6) flows down.

In addition, the outer surface of the LNG inlet header tank (12) has a heat insulating material.
(17) is attached.

Action LNG supplied is supplied from the inlet header tank (12) to the inner pipe (1
1) flows downward and is vaporized by being heated by NG which rises in the annular passage between the outer pipe (10) and the inner pipe (11), but it is a small hole (11a) arranged in the lower part of the inner pipe (11). ), LNG in the inner pipe (11) and the outer pipe (10)
NG in the inside is directly mixed through the small holes (11a), and heat can be efficiently exchanged. For example, the heat exchange tube can be shortened and downsized.

The obtained low-temperature NG is further heated while rising in the annular passage between the outer pipe (10) and the inner pipe (11), and passes through the NG outlet pipe (13) connected above the outer pipe (10). NG outlet header tank (1
It is led to 4) as NG at room temperature.

By selecting the position, size, and number of small holes (11a), the rise of the NG temperature in the outer pipe (10) can be set as desired.
It is possible to suppress the amount of ice adhered to the outer surface of the outer pipe (10) due to the decrease in the G temperature, and to prevent the occurrence of thermal stress due to the imbalance of freezing.

More specifically, as shown in FIG. 3, when the temperature at the turnaround point at the lower end of the heat exchange panel is low, the wall temperature of the outer pipe (10) becomes lower than the freezing point temperature of seawater, and the outer pipe ( Ten)
Although the ice accretion area of seawater to the inside increases, a small hole is provided on the outer circumference of the outlet side of the inner pipe (11) described above, and LNG and NG are mixed in the outer pipe (10) in a gas-liquid manner to efficiently exchange heat. Then, as shown in FIG. 4, the temperature at the turnaround point at the lower end of the panel can be increased, and the outer tube (1
It is possible to raise the pipe wall temperature of (0) to near the freezing point temperature of seawater, and it is possible to reduce the amount of seawater to be supplied by reducing ice accretion, and the power consumption of the seawater pump is significantly reduced. it can.

Also, LNG inlet header tank to which cryogenic LNG is supplied
By positioning (12) above the troughs (15) (16),
Heat input of seawater to the LNG inlet header tank (12) can be prevented, and flow rate hunting and calorie hunting to each heat exchange pipe can be prevented.

In addition, the inner tube (1
It is possible to supply NG from the lower end of 1) into the outer pipe (10) and to make a U-shaped flow that rises in the pipe and goes out from the upper end to increase the pressure loss in the pipe and stabilize the gas flow. .

Further, the open rack type vaporizer according to the present invention is
The required upper part of the inner pipe (11) to which cryogenic LNG is supplied from the G inlet header tank (12) is surrounded by a heat insulating material (17) to prevent the NG temperature from decreasing near the NG outlet. To prevent.

More specifically, by providing a heat insulating material (17) on the required upper portion of the inner pipe (11), the temperature of the NG can be controlled as shown in FIG.
The temperature of NG is raised to near the seawater temperature without decreasing near (13).

Structure 2 The double-tube open rack type vaporizer according to the present invention shown in FIG. 2 has a large number of double-tube heat exchange tubes arranged in parallel to form a heat exchange panel, which is vertically arranged. An LNG inlet header tank and an NG outlet header tank are provided on the upper part of the.

Each heat exchange tube has a required length and inner diameter, and the inner tube (21) shorter than the outer tube (20) is inserted into the outer tube (20) whose lower end is closed,
The inner bottom of the outer pipe (20) is desired to have a closed lower end of the inner pipe (21), and a small hole (21a) with a required inner diameter is provided in the lower part of the inner pipe (21) to optimize the installation range, spacing, and number. The upper end of the inner pipe (21) is located below the upper end of the outer pipe (20) by the required distance.
The upper end of the outer pipe (20) is connected to the NG outlet header tank (24) so that NG can be led out.

The LNG inlet header tank (22) has an LNG inlet pipe (23) connected to the upper portion of the inner pipe (21) through the outer pipe (20) at a required position below the NG outlet header tank (24). It is placed through.

The LNG inlet pipe (23) and the LNG inlet header tank (22) are entirely covered with a heat insulating material (28).

On the outer surface of each outer pipe (20) that constitutes the heat exchange panel, a sprinkling trough is disposed below the NG outlet header tank (24) so as to face each other.
(25) Overflow water from (26) flows down, and a sprinkling trough (2
The overflow water from 7) flows down.

Further, on the heat insulating material (28) of the LNG inlet pipe (23), overflow water from the sprinkling trough (26) below the NG outlet header tank (24) is prevented from being sprayed to the LNG inlet header tank (22) side. A shatterproof plate (29) is provided around.

The supplied LNG is introduced from the inlet header tank (22) to the inner pipe (21) through the LNG inlet pipe (23) and flows downward in the pipe to the outer pipe (20) and the inner pipe (21). ) Is vaporized by being heated by NG rising in the annular passage, but a small hole provided in the lower part of the inner pipe (21)
From (21a), LNG in the inner pipe (21) and NG in the outer pipe (20) are directly mixed through the small hole (21a), and heat can be efficiently exchanged. For example, the heat exchange pipe can be shortened and downsized. it can.

The obtained low temperature NG is further heated while rising in the annular passage between the outer pipe (20) and the inner pipe (21), and further rises in the outer pipe (20) past the upper end of the inner pipe (21). Then, it is led out as NG at room temperature to the NG outlet header tank (24) connected to the upper end of the outer pipe (20).

Further, the open rack type vaporizer according to the present invention is
An NG outlet header tank (24) is provided above the upper end of the inner pipe (21) to which cryogenic LNG is supplied from the G inlet header tank (22) by a required distance L.
Is a structure that does not indirectly exchange heat with cryogenic LNG,
It prevents the NG temperature from decreasing.

More specifically, as shown in FIG. 4, the temperature of the NG is controlled by the inner pipe (21).
The temperature is raised near the seawater temperature without lowering near the upper end of.

Structure 3 The double-tube open rack type vaporizer according to the present invention shown in FIG. 1 has an LNG inlet header tank (12) in which the heat exchange panel having the same structure as the structure shown in FIG. 1 is turned upside down.
Is located at the bottom of the panel, and the NG outlet header tank
Similarly, (14) is also juxtaposed, and there is no header tank near the sprinkling troughs (15) and (16) arranged in the upper part of the panel.

The supplied LNG is fed from the inlet header tank (12) to the inner pipe (1
1), the LNG in the inner pipe (11) and the NG in the outer pipe (10) are smaller than the small hole (11a) arranged in the upper part of the inner pipe (11).
It can be mixed directly through the heat exchanger, and the heat can be efficiently exchanged, and the same effect as that of the configuration of FIG. 1 can be obtained.

[Brief description of drawings]

1 to 3 are longitudinal explanatory views showing the structure of a double pipe type open rack type vaporizer according to the present invention. FIGS. 4 and 5 are graphs showing the temperatures of seawater, LNG, and NG by the difference in height position of the heat exchange panel. FIG. 6 is a perspective explanatory view of a single pipe type open rack type vaporizer. 10,20 …… Outer tube, 11,21 …… Inner tube, 11a, 21a …… Small hole, 12,
22 …… LNG inlet header tank, 13,23 …… NG outlet pipe,
14,24 …… NG outlet header tank, 15,16,25,26,27…
… Sprinkling trough, 17,27,28 …… Insulation, 29 …… Splash prevention plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoji Sato 2-6 Nishi-Nasusu Hon-dori, Amagasaki City, Hyogo Prefecture Sumitomo Precision Industries, Ltd. (72) Inventor Yu Akiyama Nishi-Nagamoto-dori, Amagasaki City, Hyogo Prefecture Address 6 Sumitomo Precision Industries, Ltd.

Claims (2)

[Claims] 1. A heat exchange panel is formed by arranging a large number of heat exchange tubes having a double-tube structure, and a liquefied gas inlet header tank and a vaporized gas outlet header tank are arranged above the heat exchange panel, and below each header tank. A sprinkling trough is installed in the inner pipe to allow liquefied gas to flow downward from the upper part of the inner pipe, and a small hole provided on the outer periphery of the lower part of the inner pipe with a closed lower end or a lower end with small holes A double-tube open-rack type vaporizer which is capable of gas-liquid mixing and which causes vaporized gas to flow out by raising an annular passage between an outer pipe and an inner pipe. 2. A heat exchange panel is formed by arranging a large number of heat exchange tubes having a double pipe structure, and a liquefied gas inlet header tank and a vaporized gas outlet header tank are arranged below the heat exchange panel, and above the panel. The liquefied gas is made to rise from the lower part of the inner pipe, and a small hole is provided in the upper outer periphery of the inner pipe having a closed upper end or an upper end with small holes to mix gas-liquid in the upper inner part of the outer pipe. A double-tube open rack type vaporizer characterized in that the vaporized gas is led out by descending an annular passage between an outer pipe and an inner pipe as much as possible.