KR980010314A - Heat exchanger for vaporizing liquefied natural gas - Google Patents

Abstract

The present invention discloses a heat exchange apparatus for vaporizing liquefied natural gas by using double tubes for circulating liquefied natural gas and circulating seawater outside the tubes.

The present invention is characterized in that a baffle is provided in a heating section constituted by a merging chamber constituted by a plurality of double tubes constituted of an inner tube and an outer tube and a heating section constituted by a heat transfer tube provided between an outlet and an outlet of a confluence chamber to form a circulation path, It is.

Thus, the seawater is brought into contact with the liquefied natural gas for a sufficient time, vaporized in the inner pipe, sufficiently exchanged heat with the sea water while passing through the outer pipe, and sufficiently heated by the initial heat of the seawater The heat exchange efficiency can be improved by the fin, and the vibration and the stress can be prevented from being concentrated, thereby reducing the amount of seawater and electric power used and providing a heat exchanger with excellent durability. The operation range according to the inlet temperature is wide and stable operation is possible in winter.

Description

Heat exchanger for vaporizing liquefied natural gas

Fig. 1 (a) and Fig. 2 (b) are explanatory views showing a heat exchanger for vaporizing liquefied natural gas of ORV type.

FIG. 2 is an explanatory view showing a heat exchange device for vaporizing liquefied natural gas according to the present invention; FIG.

FIG. 3 is a cross-sectional view of a dual tube with a fin as a further embodiment of a heat exchanger device according to the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

1: inlet 2: inner tube

3: outer tube 4: confluence chamber

5: vaporizer 6: outlet

7: heat transfer pipe 8:

9: Baffle 10: Seawater inlet

11: Sea water discharge route 12: Circulation route

13: pin

The present invention relates to a heat exchanger for vaporizing LNG (Liquefied Natural Gas) to make natural gas. More specifically, the present invention relates to a heat exchanger that vaporizes liquefied natural gas by raising the temperature of LNG using a heat source such as seawater To a heat exchanger for liquefied natural gas vaporization.

LNG is an acronym for Liquified Natural Gas, which is a colorless, odorless, -162 ° C clear, cryogenic liquid with a volume reduced to 1/600 by cooling in a natural gas source for transportation and storage of underground natural gas. It says. The liquefied LNG is transported to the LNG receiving station by the LNG carrier and stored in the specially manufactured LNG storage tank. The stored LNG is vaporized in the LNG vaporizer for supply to the customer.

As we all know, since LNG receiving bases are adjacent to the coast, seawater is used as a heating source for LNG vaporization considering operating costs.

An open rack vaporizer (ORV) is widely used in Korea and abroad as a typical vaporizer that uses seawater as a heat source. Such an open rack vaporizer is responsible for the base vaporization amount of vaporization required at the receiving base.

The structure of such an open rack vaporizer is shown in FIG. This is because -162 ° C LNG introduced from the LNG header 101 is vaporized while passing through the heat transfer pipe 102 and discharged through the NG header 104. At this time, 10-20 ° C seawater is supplied to the outside of the LNG vaporizer 103, so that the LNG is vaporized at a temperature of 0 ° C or higher while the temperature of the LNG is raised by the heat input from the seawater, and the vaporized natural gas is discharged to the natural gas supply pipe .

In order to prevent thermal stress such as twisting due to uneven temperature distribution from occurring in the heat exchanger tube, the temperature of the outside of the vaporizing tube must be uniformly maintained at each cross section of the vaporizing tube, It should be poured out.

Accordingly, even if the amount of LNG vaporized is reduced, a sufficient amount of seawater is supplied over a certain amount, resulting in an economical disadvantage that an unnecessarily large amount of power is consumed for operating the seawater pump for supplying seawater.

In addition, since the seawater flows in contact with the heat exchanger tube at a high speed under gravity, the heat exchange efficiency is lowered and the heat exchange area must be increased. Thus, the occupied area of the facility is unnecessarily increased and the overall height of the heat exchanger is increased. As a result, corrosion and seawater floating substances are attached to the star pin type structure built in the outside of the used vapor pipe for a long period of operation, and the height of the vaporizer pipe is high, which makes it difficult to maintain and repair the vessel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat exchanger for liquefied natural gas vaporization which improves heat transfer efficiency and minimizes thermal stress due to vaporization of a cryogenic fluid. In order to achieve the above-mentioned object, the present invention provides an LNG vaporizing unit including a plurality of double pipes each composed of an inner pipe and an outer pipe, and configured to increase the temperature of the vaporized LNG to 0 ° C or higher, The LNG gasification unit and the temperature rise unit are discharged after circulating the seawater. Optionally, the LNG vaporizer can operate at a high pressure of 40 bar or more by using a heat transfer pipe having a pin formed in the inner pipe and the outer pipe of the double pipe. A heat exchanger for a liquefied natural gas vaporizer is proposed.

According to the present invention, the heat exchange efficiency is greatly improved and the apparatus can be made compact, and the seawater consumption can be reduced, thereby reducing the occupied area of the facility and reducing the power consumption of the seawater pump. Can be reduced.

In addition, the heat exchanger of the present invention prevents the direct contact of the LNG having a temperature of -162 ° C with the seawater by the dual pipe structure, minimizing the possibility of freezing the seawater in the heat transfer pipe and minimizing the generation of thermal stress due to the LNG vaporization So that the durability of the device can be improved and the life of the device can be extended.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

2 shows a first embodiment of the present invention in which an inlet 1 for supplying LNG and an inner pipe 2 and an outer pipe 3 through which the LNG flows are constituted by a confluence chamber 4 in which a plurality of double pipes are fixedly connected by a wall, A temperature raising section 8 composed of a vaporizing section 5 and a heat transfer tube 7 connected to an outlet of the confluence chamber 4 and a discharge port 6 through which the vaporized natural gas is heated to be discharged; The circulation path 12 formed by the baffle 9 dividing the periphery of the septum 8 communicates with the seawater inlet 10 and the seawater discharge passage 11.

In the heat exchanger according to the present invention, LNG having a temperature of -162 ° C. is injected through the injection port 1 and then passes through the inner pipe 2 of the inner pipe 2 and then through the outer pipe 3, And then exchanges heat with the seawater circulating around the outer tube 3 while passing through the outer tube 3 to continuously heat the vaporizing heat that the LNG passing through the inner tube 2 can vaporize .

Accordingly, since the inner tube 2, which is the LNG vaporization part 5, is in indirect contact with the seawater, the occurrence of thermal stress can be minimized. Since the inner tube 2 is free from one end, It is possible to effectively absorb the thermal stress due to the extremely low temperature.

In addition, these double tubes have the same effect as extended by a length corresponding to twice the actual length, so that heat exchange is possible for a sufficient time.

In the present invention, as shown in the third figure, by attaching the fin 13 to the inner pipe 2 and the outer pipe 3 of the double pipe, high-pressure LNG of 40 bar or more generated due to use as the LNG vaporizer is introduced, So that it is possible to reinforce the structural weakness that the stress is concentrated on the wall of the confluence chamber 4 due to the self-weight of the pipe itself.

Also, the heat transfer efficiency between the inner pipe 2 and the outer pipe 3 of the LNG evaporation pipe 2 can be greatly improved by the fin 13 of the inner pipe 2, thereby further increasing the heat exchange efficiency.

Such a heat exchanger is firstly greatly reduced in length by a double pipe structure, thereby enabling a compact heat exchanger design, thereby reducing the occupied area. Moreover, since the inner pipe 2 is not in direct contact with seawater, So that it is possible to extend the service life.

In addition, since the natural gas is to be supplied to the customer in the heat exchanger by raising the temperature of the natural gas by 0 ° C or more, the temperature rising portion 8 of the natural gas is constituted by the U-shaped heat transfer pipe 7.

Accordingly, when the temperature of the seawater in the winter season falls below 5 ° C due to the fluctuation of the hot water of the seawater caused by the LNG heating according to the seasons, it is impossible to supply natural gas at a temperature of 0 ° C or higher to the vaporizer according to the conventional technology. .

Since the natural gas temperature rising part is separately installed and heated by the inlet temperature of the sea water, natural gas can be supplied at a temperature of 0 ° C or higher even if the temperature of the seawater is low, and the operation range according to the inlet temperature of the sea water is wide. In addition, the heat exchanger of the present invention can be designed to facilitate disassembly and assembly so that it can be used for maintenance and repair due to corrosion caused by seawater and adhesion of contaminants.

The heat exchanger can increase the residence time by adjusting the number of installed baffles 9 and so on, thereby greatly reducing the amount of seawater used compared to the vaporizer. Therefore, it is possible to operate the seawater pump appropriately Therefore, it is possible to reduce the operating cost by reducing the power cost and the like.

Claims (2)

A gasification unit 5 comprising an injection port 1 through which LNG is supplied, an inner pipe 2 through which the LNG flows, and a confluence chamber 4 in which a plurality of double pipes composed of an outer pipe 3 are fixed by a wall, And a heat transfer pipe 7 connected to an outlet of the confluence chamber 4 and an outlet 6 through which the vaporized natural gas is heated to be discharged and a heat transfer pipe 7 connected to the gasification unit 5 and the temperature- Wherein the circulation path (12) formed by the baffle (9) for partitioning the peripheries is communicated with the seawater inlet (10) and the seawater discharge path (11). 2. The heat exchange apparatus for liquefied natural gas vaporization according to claim 1, wherein a plurality of fins (13) are installed on the inner tube (2) and the outer tube (3) of the dual tube. ※ Note: It is disclosed by the contents of the first application.