KR980010315A - Liquefied natural gas heat recovery heat exchanger - Google Patents

Abstract

The present invention proposes a cold heat recovery heat exchanger in which a cold heat recovery of liquefied natural gas and a heat exchanger for vaporization and temperature rise are installed in one casing.

The present invention circulates a refrigerant for recovery and vaporization of liquefied natural gas, while allowing cold water to be recovered and vaporized natural gas is heated by seawater so that it can be directly supplied to a consumer.

Accordingly, the present invention can reduce the occupied area of the cold heat recovery heat exchanger and reduce the installation investment cost, thereby improving the economical efficiency of the cold utilization industry and reducing the thermal stress and improving durability Since the LNG cold recovery and the temperature rise of the gas are performed in a single device, application of the temperature and flow control technology in the device is easy and easy to control.

Description

Liquefied natural gas heat recovery heat exchanger

FIG. 1 is an explanatory view showing a conventional heat exchanger for liquefied natural gas heat recovery; FIG.

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

FIG. 3 is a cross-sectional view of a double pipe in which a fin is formed as another embodiment of the heat exchanger for recovering liquefied natural gas cold heat according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

2: inner tube 3: outer tube

4: confluence chamber 5: cold /

6: discharge port 7: heat transfer pipe

8: Heating section 9: Insulating partition plate

10: Baffle 11: Refrigerant inlet

12: Refrigerant outlet port 13: Seawater inlet

14: Sea water discharge 18: Pin

The present invention relates to a LNG cold heat recovery heat exchange system capable of operating at a high pressure of 40 bar or more to utilize the cold heat possessed by LNG.

LNG is an abbreviation for Liquified Natural Gas, which is a colorless, odorless, -162 ° C clear, cryogenic liquid that reduces the volume to 1/600 by cooling it in the natural gas source to transport sediment. It says. LNG (Liquefied Natural Gas) is transported to LNG receiving bases by LNG transport in the mountains and stored in specially manufactured LNG storage tanks. LNG is vaporized in LNG vaporizer to supply to customers. LNG has a total of 200Kcal of cooling energy per 1 KG, and the heat medium such as seawater and the sea water after heat exchange are discarded to the outside in vaporization process to be able to use in gas demand place.

The conventional method of vaporizing LNG using such seawater is to discharge the cold energy of LNG to the outside and to dispose of it and to consume the electric energy equivalent to 0.7% of the cold heat of LNG in driving the pump to transport seawater There is a monster point where the valuable energy resources can not be utilized and the cold heat is discharged and discarded to the outside.

Therefore, there are several attempts to improve the operating efficiency of the LNG receiving terminal and contribute to energy saving by utilizing the LNG cold heat, which is discarded to the outside.

The representative example is gathered on the first road.

As can be seen, conventionally, the liquefied natural gas is fused into the LNG cold heat recovery heat exchanger 101, vaporized by the refrigerant, passed through the vaporizing gas heater 102, heated to be discharged after being heated, The refrigerant recovered from the LNG cold heat in the LNG heat exchanger 101 is allowed to pass through the refrigerant utilization facility 104 by the pressure transmission of the LNG heat exchanger 103 by using the LNG cold heat recovered by the refrigerant.

These refrigerant utilization facilities are used in various fields such as cold power generation, air liquefaction separation business (liquid oxygen, liquid nitrogen), dry ice, low temperature food storage and freezing, low temperature crushing of acid waste, ice link and cooling.

In this system, LNG is heat-exchanged with a cooling medium such as brine oil, freon, etc., and the heat exchanged LNG is in a low temperature state below 0 ° C which is a mixture of gas or gas and liquid. It should be warmed up. For this purpose, a natural gas heater that heats natural gas by using seawater is installed, and natural gas is passed through it. Then, the natural gas which is heated is used as fuel required for operating the own gas receiving station. And supplies them to the facilities.

Therefore, the above-mentioned method requires additional cost of natural gas heater installation and seawater pump power for operation, and when plate heat exchanger is used for LNG cold heat recovery, it must be operated at low pressure, .

Therefore, since the compressor power for recompression is required, the operation cost is increased and the economical efficiency of the LNG cold heat utilization industry is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an apparatus and a method for reducing the installation area and investment cost of a conventional art, and capable of operating at a high pressure of 40 bar or more, The present invention proposes a heat exchanger which can extend the service life of the device by minimizing the occurrence of thermal stress and thermal fatigue due to contact with cryogenic liquid, without necessitating recompression to supply natural gas to customers.

In order to achieve the above-mentioned object, the present invention provides a heating and cooling unit including a cold / hot water recovering unit in which a plurality of double pipes composed of an inner pipe and an outer pipe are fixed to one side of a confluence chamber, and a heat transfer pipe between an outlet and an outlet of the confluence chamber. The heat recovery section and the temperature rising section are separated by the heat insulating partition plate having the heat insulating performance and the respective baffles are provided on the heat exchange partition section and the separate circulation path is provided and these circulation paths are connected to the refrigerant inlets and the refrigerant outlets, So as to provide a heat exchanger for recovering liquefied natural gas.

According to the above-described construction, the heat exchanger for use of cold heat and the natural gas heater for raising the natural gas by sea water can be embedded in one casing, thereby enabling a compact design of the heat exchanger, The thermal stress can be minimized and the thermal fatigue can be minimized. Therefore, it is possible to extend the service life of the device, and the LNG heat recovery Process and the temperature rise of vaporized gas are simultaneously performed in one device, so that the control technology is easy to apply and temperature control is easy.

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

As shown in FIGS. 2 and 3, the present invention comprises an inlet 1 for injecting cryogenic liquefied natural gas at -162 ° C, an inner tube 2 communicating with the inlet 1, And a confluence chamber 4 communicating with the outer tube 3 in which a plurality of double tubes each composed of an inner tube 2 and an outer tube 3 are fixed to the outer tube 3 communicating with one end of the outer tube 3 And a heat transfer pipe 7 connected to the outlet of the heating chamber 4 and the discharge port 6. The heat insulating partition plate 9 is provided between the cold heat recovery unit 5 and the temperature rising unit 8, ).

The circulation passages are formed between the baffles 10 provided with the baffles 10 around the outer tube 3 and the heat transfer tube 7 of the temperature rising section 8 and the cold and hot water recovering section 5, Are connected to the coolant inlet port (11), the coolant outlet port (12), and the seawater inlet port (13) and the seawater outlet port (14), respectively.

The coolant inlet port 11 is connected to the coolant utilization facility 17 and the coolant drum 15 and the pump 16 and the coolant utilization facility 17 as shown in FIG. And connected to the connection pipe.

In the present invention as described above, the ultra-low temperature LNG is injected through the injection port 1 and is introduced into the inner pipe 2 of the double pipe to be vaporized.

The vaporized natural gas then passes through the outer tube 3, where the heat of the refrigerant circulating around the outer tube 3 is applied to the natural gas and the natural gas again heats the LNG flowing through the inner tube 2 So that the process of continuously vaporizing LNG is repeated.

The vaporized LNG is collected in the confluence chamber 4. At this time, the coolant flows through the coolant inlet port 11 and recovers the cold heat of the LNG while passing through the circulation path to be discharged to the coolant outlet port 12. [

The refrigerant thus flowed flows to the pump 16 through the refrigerant drum 15 and is fed by the pump 16 to be supplied to the cold heat utilization facility 17 so that cold heat generated by the refrigerant can be diverted and utilized And the heated refrigerant flows into the refrigerant inlet 11.

In this process, the cold recovery unit 5 and the natural gas heating unit 8 are provided with a heat insulating partition plate 9 containing a heat insulating material so as to block the heat inflow and use the cold heat to the cold heat collecting unit 5 And the natural gas heating unit 8 does not require a natural gas heater by sifting the natural gas at 0 ° C or more by heat exchange with seawater. Therefore, the present invention can make the whole facility extremely compact, and can reduce the occupied area, thereby reducing the capital investment cost.

In order to prevent recompression of the vaporized gas, the present invention must be capable of operating at a high pressure of 40 bar or more. Therefore, when the LNG is vaporized in the cylindrical portion, high-pressure gas may leak from the cylinder- And the seawater flows through the outer cylindrical portion of the outer pipe 3 side.

In addition, the cold / hot water recovering unit 5 of the heat exchanger has a double pipe structure in order to minimize generation of thermal stress due to LNG vaporization of -162 ° C which is a cryogenic liquid, and the inner pipe 2 is free from contraction due to ultra- You can minimize your hassle.

The dual tube type heat exchanger has a structure disadvantage that the stress of the internal tube 2 is concentrated due to the vibration of the heat transfer tube due to the inflow of high pressure LNG of 40 bar or more and the vaporization of the heat transfer tube itself and the internal disadvantage of the LNG, There is a problem that the tube inside the dual tube is longer than necessary due to the difference in heat transfer rate with the natural gas as the gas. Accordingly, in the present invention, by using the inner tube 2 and the outer tube 3 to which the plurality of fins 18 are attached as shown in the third road, the contact between the fin 18 and the outer tube 3, It is possible to prevent the vibration and improve the heat exchange efficiency by satisfying both the supporting action for suppressing the vibration of the LNG evaporator 7 and the heat transfer area securing the heat transfer rate difference between the inside and outside of the LNG evaporating tube.

Claims (2)

A plurality of double tubes each composed of an inner tube 2 and an outer tube 3 are fixed to one side of the confluence chamber 4 and a heat transfer tube 5 is disposed between the outlet of the confluence chamber 4 and the discharge port 6, The heat recovery section 5 and the temperature rising section 8 are divided into a heat insulating partition plate 9 having heat insulating performance and the baffles 10 And the circulation paths are connected to the refrigerant inlet port 11 and the refrigerant outlet port 12 and the seawater inlet port 13 and the seawater outlet port 14, respectively, Recovery heat exchanger. The heat exchanger according to claim 1, wherein a plurality of fins (18) are formed in the inner pipe (2) and the outer pipe (3) of the dual pipe. ※ Note: It is disclosed by the contents of the first application.