KR100198695B1 - Heat exchanger for lng - Google Patents

Abstract

The present invention discloses a heat exchange apparatus for liquefied natural gas vaporization which uses a double pipe in vaporizing liquefied natural gas and circulates seawater to the outside thereof.

The present invention forms a circulation path by installing a baffle in a vaporization unit consisting of a confluence chamber consisting of a plurality of double pipes composed of an inner tube and an outer tube and a heat transfer tube installed between an outlet and an outlet of the confluence chamber, thereby forming a circulation path. It is.

Accordingly, the seawater comes into contact with the liquefied natural gas for a sufficient time, and vaporizes in the inner tube and sufficiently heat exchanges with the seawater while passing through the outer tube. It is possible to improve heat exchange efficiency by fins and to avoid concentration of vibration and stress, and to reduce the use of sea water and electric power, to provide a heat exchanger with high durability, and to install a natural gas heating unit separately. The wide operating range according to inlet temperature enables stable operation even in winter.

Description

Heat exchanger for liquefied natural gas vaporization

(A), (b) of FIG. 1 is explanatory drawing which showed the heat exchanger for ORV type | system | group nuclear gas vaporization.

2 is an explanatory view showing a heat exchanger for liquefied natural gas vaporization according to the present invention.

3 is a cross-sectional view showing a double tube with a piece as another embodiment of the heat exchanger according to the present invention.

* Explanation of symbols for main parts of the drawings

1: injection hole 2: inner tube

3: exterior hall 4: confluence room

5: vaporization part 6: outlet

7: heat transfer tube 8: heating unit

9: baffle 10: seawater inlet

11: seawater discharge path 12: net runway

13: pin 14: copper plate

15: tube

The present invention relates to a heat exchanger for vaporizing liquefied natural gas (LNG) into natural gas. In more detail, the temperature of LNG is increased by using a heat source such as seawater to vaporize liquefied natural gas. It relates to a heat exchanger for liquefied natural gas vaporization.

LNG stands for Liquified Natural Gas, which is a colorless, odorless, transparent, cryogenic liquid with a volume reduced to 1/600 by cooling in natural gas producing areas for transportation and storage of natural gas extracted from the underground. Say. The liquefied LNG is transported from the mountain to the LNG takeover base by the LNG carrier and stored in a specially manufactured LNG storage tank. The stored LNG is vaporized in an LNG vaporizer for supply to the customer.

As it is known, since LNG takeover bases are generally adjacent to the coast, seawater is used as a heating source for LNG vaporization in consideration of operating costs.

An open rack vaporizer (ORV) is widely used at home and abroad as a representative vaporizer using seawater as a heat source, and the open rack vaporizer is responsible for the amount of vaporization required at the receiving base.

The structure of this open rack vaporizer is shown in FIG. This is -162 ℃ LNG introduced from the LNG Header 101 is vaporized while passing through the heat transfer pipe 102 is discharged through the NG Header 104, at this time 10 ~ 20 ℃ sea water outside the LNG vapor pipe pipe seawater and aquatic equipment ( It is to flow down to the falling film type through 103), so that the temperature of LNG rises to 0 ° C or higher by heat oil from sea water, and thus the vaporized natural gas is discharged to natural gas supply pipe. It is structured.

The open rack heat exchanger of such a structure should flow outside the vaporization pipe in order to prevent thermal stress such as staggering due to uneven temperature distribution of the heat exchanger tube.

Accordingly, even if the amount of vaporization of LNG is reduced, a sufficient amount of seawater is supplied, thereby causing an economic disadvantage in that a large amount of power is consumed unnecessarily to operate a seawater pump for seawater supply.

In addition, since the seawater flows in contact with the heat exchanger tube at a high speed under gravity, the heat exchange rate is decreased to increase the heat exchange area. Accordingly, the occupied area of the equipment is unnecessarily increased, thereby increasing the total height of the heat exchanger. Therefore, when driving for a long time, there is a problem that it is difficult for maintenance and repair work such as cleaning due to high height of the opportunity pipe having a high degree of corrosion or seawater attached to the star pin structure built outside the opportunity pipe.

An object of the present invention is to propose a heat exchanger for liquefied natural gas vaporization to improve the heat transfer efficiency and to minimize the thermal stress caused by the vaporization of cryogenic fluid.

In order to achieve the above object, the present invention comprises a LNG vaporizing unit by providing a plurality of double tubes composed of an inner tube and an outer tube, and as a temperature rising unit of natural gas (NG) for raising the vaporized LNG to 0 ° C. or more. The LNG vaporization unit and the temperature rising part are discharged after circulating the seawater, and the LNG vaporization unit can be operated at a high pressure of 40 bar or more by using an inner tube of a double pipe and a heat transfer tube provided on one side of the outer pipe. A heat exchanger for liquefied natural gas vaporizer is proposed.

By the above-described configuration, the present invention can greatly improve the heat exchange efficiency to enable the compactness of the device, and it is possible to reduce the amount of seawater used, thereby reducing the occupied area of the facility and reducing the power consumption of the seawater pump, thereby reducing the facility cost and maintenance cost. Can be reduced.

In addition, the heat exchange apparatus according to the present invention prevents LNG having a -162 ° C from coming into direct contact with the sea water by the double pipe structure, thereby minimizing the possibility of sea ice freezing outside the heat transfer pipe and minimizing the generation of thermal stress due to LNG vaporization, which is a cryogenic liquid. It is effective.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 2, the present invention provides an inlet 1 through which LNG is supplied, a tube 15 through which LNG flows, and a tube 15 fixed to a copper plate 14 and a baffle 9, and a tube 15. The confluence chamber (4) where the LNG flowing through the ()), the discharge port (11) through which the joined LNG is discharged, and the water injected from the water inlet (10) are sufficiently exchanged with the tubular body (15) by the baffle (9). In the well-known thing comprised of the circulation path 12 and the water discharge port 11 for making it, the internal pipe 2 which made the pipe 15 double-communicate, and communicated with the injection port 10, and the confluence room 4 ), The heat pipe (7) installed between the confluence chamber (4) and the outlet (6) and fixed by the baffle (9), the tubular body (15) and the heat pipe (7) It consists of the vaporization part 5 and the temperature rising part 8 formed by partitioning this installed space.

The heat exchanger according to the present invention thus passed through the inner tube (2) of the double tube after LNG is injected through the inlet (1) and then through the outer tube (3) the inner tube (2) It is vaporized in the process of passing through and then heat exchange with the sea water circulating around the outer tube (3) while passing through the outer tube (3) to continuously evaporate heat that the LNG passing through the inner tube (2) can vaporize Will be supplied.

Accordingly, the inner tube 2 of the LNG vaporization unit 5 and the sea water is indirect contact, so that the occurrence of thermal stress can be minimized. Since the inner tube 2 is freely left at one end, the ultra low temperature Shrinkage of the heat transfer pipe by freely and can effectively absorb the thermal stress caused by cryogenic temperatures.

In addition, such a double pipe will have the same effect as extending the length of twice the actual length, it is possible to heat exchange for a sufficient time even in a small volume of facilities.

In addition, the present invention, as shown in FIG. 3, by attaching the pin 13 to the inner tube 2 and the outer tube 3 of the double tube, the high pressure LNG of 40 bar or more generated by using as a vaporization device for LNG is introduced and vaporized It is possible to reinforce the structural weakness that absorbs the vibration by the stress and concentrates the stress on the wall of the joining chamber 4 due to the weight of the tube itself.

In addition, the fin 13 of the inner tube 2 can significantly increase the heat transfer efficiency of the LNG tube inner tube 2 and the outer tube 3 to further increase the heat exchange efficiency.

These heat exchangers are first reduced in length by the double tube structure, which enables compact heat exchanger design, reducing the occupied area, and also because the inner tube (2) is not in direct contact with the sea water, and there is no fear of corrosion due to sea water and thermal stress. Can be minimized to extend its lifespan.

In addition, the present invention is to heat the natural gas in the heat exchanger 0 ° C or more to supply to the demand, so for this purpose the U-shaped heat pipe (7) constitutes the temperature rising portion 8 of the natural gas. Therefore, if the temperature of the seawater, the LNG heating source, fluctuates according to the season and the temperature of the seawater falls in winter or less than 5 ℃, it is impossible to supply natural gas above 0 ℃ by the vaporizer according to the prior art. Done.

In the present invention, since the natural gas heating unit is separately installed and heated by the seawater inlet temperature, even if the temperature of the seawater is low, natural gas can be supplied more than 0 ° C., and the operating range according to the seawater inlet temperature is wide. In addition, the heat exchanger of the present invention can be structural design to be convenient for maintenance and repair due to corrosion and contamination of the water by the seawater.

The heat exchanger can extend the residence time by controlling the number of installation of the baffle (9), the proper flow rate of the seawater can significantly reduce the seawater consumption than the conventional open-rack vaporizer, and therefore the capacity of the seawater pump properly Can be operated to reduce the operating cost by reducing power costs.

Claims (2)

The inlet 1 through which the LNG is supplied, the conduit 15 in which the LNG flows and the conduit 15 fixed to the copper plate 14 and the baffle 9, and the confluence chamber 4 in which the LNG flowing through the conduit 15 are collected, are joined. The outlet 11 through which the LNG is discharged, the circulation passage 12 for allowing sufficient heat exchange with the tubular body 15 by the baffle 9, and the water injected into the water inlet 10, and the water outlet 11. In the known configuration, the inner tube (2) having a double structure of the tubular body (15) to communicate with the inlet (10), the outer tube (3) to communicate with the confluence chamber (4), the confluence chamber ( 4) and the vaporization part 5 and the temperature rising part which are divided and partitioned between the heat exchanger tube 7 installed between the discharge port 6 and the baffle 9, and the space in which the tube body 15 and the heat exchanger tube 7 were installed. Heat exchanger for liquefied natural gas vaporization, characterized in that consisting of (8). The heat exchanger for liquefied natural gas vaporization according to claim 1, characterized in that a plurality of fins (13) are erected on the inner tube (2) and the outer tube (3) of the tube body (15).