KR20150042085A - A Heat System of Liquefied Natural Gas - Google Patents

A Heat System of Liquefied Natural Gas Download PDF

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Publication number
KR20150042085A
KR20150042085A KR20130120849A KR20130120849A KR20150042085A KR 20150042085 A KR20150042085 A KR 20150042085A KR 20130120849 A KR20130120849 A KR 20130120849A KR 20130120849 A KR20130120849 A KR 20130120849A KR 20150042085 A KR20150042085 A KR 20150042085A
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KR
South Korea
Prior art keywords
seawater
lng
heat exchanger
supply line
heat
Prior art date
Application number
KR20130120849A
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Korean (ko)
Inventor
백은성
Original Assignee
현대중공업 주식회사
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Priority to KR20130120849A priority Critical patent/KR20150042085A/en
Publication of KR20150042085A publication Critical patent/KR20150042085A/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
    • B63B27/24—Arrangement of ship-based loading or unloading equipment for cargo or passengers of pipe-lines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
    • F17C7/02—Discharging liquefied gases
    • F17C7/04—Discharging liquefied gases with change of state, e.g. vaporisation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
    • F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Ocean & Marine Engineering (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

An LNG heating system according to an embodiment of the present invention includes: an LNG supply line connected from an LNG supply source to a customer; An LNG heat exchanger provided on the LNG supply line for exchanging heat with the LNG discharged from the LNG supply source; A seawater supply line for receiving seawater from the sea, delivering the seawater to the LNG heat exchanger, and discharging seawater heat-exchanged with the LNG to the sea; And a seawater treatment device provided on the seawater supply line upstream of the LNG heat exchanger to reduce salinity of the seawater supplied to the LNG heat exchanger.
Since the LNG heating system according to the present invention exchanges heat with the LNG using the seawater whose supply amount and discharge are easier than the fresh water without using only fresh water having a limited storage space and limited supply amount in the ship, It is not necessary to immediately reuse the heat exchange material cooled by the LNG, and thus the driving of the heater for reheating can be reduced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a LNG heating system,

The present invention relates to an LNG heating system.

LNG is known to be a clean fuel and its reserves are richer than petroleum, and its use is rapidly increasing as mining and transfer technology develops. This LNG is generally stored in a liquid state at a temperature of -162 ° C. or below under 1 atm. The volume of liquefied methane is about one sixth of the volume of methane in a gaseous state, The specific gravity is 0.42, which is about one half of that of crude oil.

Such LNG can be stored in a LNG storage tank in the form of a pressure tank. In an LNG supplier who wants to use LNG, heat exchange is required because LNG at cryogenic temperature can not be used as it is.

On the other hand, in order to heat exchange the LNG, a separate electric equipment such as a heater is used. In this case, it is necessary to reduce the consumption of electricity for exchanging heat with the LNG, and to prevent environmental pollution. The following description will be made with reference to the drawings.

1 is a conceptual diagram of an LNG heating system according to an embodiment of the present invention.

1, the conventional LNG heating system 1 includes an LNG heat exchanger 30, a seawater supply line 31, a first seawater heat exchanger 41, and a second seawater heat exchanger 42 can do. The LNG heat exchanger 30 exchanges LNG supplied from the LNG supply source 10 with heat to raise the temperature to a temperature required by the customer 20. The LNG supply line 11 through which the LNG flows is supplied to the LNG supply source 10, The heat exchanger 30, and the consumer 20.

The first seawater heat exchanger 41 may be a heater and may heat the seawater to raise the temperature of the seawater to a temperature sufficient for the seawater to sufficiently heat the LNG. The second seawater heat exchanger 42 performs heat exchange so that the sea water cooled by the LNG is similar to the sea temperature. Here, the sea water supply line 31 is connected to the sea chester, the first seawater heat exchanger 41, the LNG heat exchanger 30, the second seawater heat exchanger 42, and the sea chester so that seawater can pass through.

Such an LNG heating system 1 uses seawater containing salt to corrode iron, so that the seawater may damage the piping (seawater supply line) or the heat exchanger (30, 41, 42) Replacement may occur frequently. In contrast, fresh water is used as follows.

2 is a conceptual diagram of an LNG heating system according to another embodiment of the present invention. The components having the same functions as the LNG heating system 1 according to the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The conventional LNG heating system 2 according to another embodiment may include an LNG heat exchanger 30, a seawater supply line 32, a third seawater heat exchanger 43 and a fresh water tank 50.

Unlike the LNG heat exchanger 30 in the LNG heating system 1 of one embodiment, which uses seawater, the LNG heating system 2 of the present embodiment uses fresh water to prevent corrosion of the heat exchangers 30 and 43 (See Patent Document 10-2013-0052312).

The fresh water tank 50 stores fresh water supplied to the LNG heat exchanger 30 and the LNG heat exchanger 30 receives fresh water heat-exchanged in the third seawater heat exchanger 43 to heat exchange the LNG.

Since the LNG heating system 2 uses only fresh water supplied from the fresh water tank 50 to heat-exchange the LNG, the fresh water tank 50 must be sufficiently large as the amount of fresh water for heat exchange must be sufficient. However, There is a limit in the characteristics of the ship where the restriction of In addition, when an abnormality occurs in the supply of fresh water due to leakage of clear water or the like, it is difficult to replenish fresh water, thereby causing a problem in heat exchange of the LNG. In addition, there is a problem that the third seawater heat exchanger 43 must be continuously operated to heat the LNG as the fresh water cooled by the LNG is reused by returning fresh water.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to reduce the corrosion of steel structure due to a large amount of salt contained in seawater, The present invention is intended to provide an LNG heating system capable of reducing the driving of the heater for reheating the cooled fresh water without excessively demanding it.

An LNG heating system according to an embodiment of the present invention includes: an LNG supply line connected from an LNG supply source to a customer; An LNG heat exchanger provided on the LNG supply line for exchanging heat with the LNG discharged from the LNG supply source; A seawater supply line for receiving seawater from the sea, delivering the seawater to the LNG heat exchanger, and discharging seawater heat-exchanged with the LNG to the sea; And a seawater treatment device provided on the seawater supply line upstream of the LNG heat exchanger to reduce salinity of the seawater supplied to the LNG heat exchanger.

Here, the present invention provides a seawater pump provided on the seawater supply line and raising seawater from the sea; And a buffer tank provided on the seawater supply line downstream of the seawater pump for receiving and storing seawater from the seawater pump.

The present invention is further characterized by a first seawater heat exchanger provided on the seawater supply line upstream of the LNG heat exchanger, for receiving seawater from the buffer tank and performing heat exchange.

The present invention further includes a second seawater heat exchanger provided on the seawater supply line downstream of the LNG heat exchanger and performing heat exchange with seawater discharged from the LNG heat exchanger corresponding to the temperature of the sea.

Further, the present invention is characterized by further comprising a first detour line branching and joining at the seawater supply line, and bypassing the second seawater heat exchanger.

In addition, the seawater supply line is characterized in that seawater is heat-exchanged via a heating device in the ship, downstream of the LNG heat exchanger.

The present invention further includes a second bypass line that branches off from the seawater supply line and merges, bypassing the heating device.

In addition, the seawater supply line discharges seawater to the sea via the outer tank of the vessel, downstream of the LNG heat exchanger.

In addition, the outer tank of the ship is in contact with the sea in the hull and a space is formed to exchange heat between seawater passing through the seawater supply line and sea water.

Since the LNG heating system according to the present invention exchanges heat with the LNG using the seawater whose supply amount and discharge are easier than the fresh water without using only fresh water having a limited storage space and limited supply amount in the ship, It is not necessary to immediately reuse the heat exchange material cooled by the LNG, and thus the driving of the heater for reheating can be reduced.

Further, the present invention can heat the LNG using a common iron material without using an expensive material that reduces the amount of salt by treating the seawater to prevent damage due to salt, so that the manufacturing cost of the heat exchanger Can be saved.

1 is a conceptual diagram of an LNG heating system according to an embodiment of the present invention.
2 is a conceptual diagram of an LNG heating system according to another conventional example
3 is a conceptual diagram of an LNG heating system according to an embodiment of the present invention.

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

3 is a conceptual diagram of an LNG heating system according to an embodiment of the present invention.

3, an LNG heating system 100 according to an embodiment of the present invention includes an LNG heat exchanger 130, a seawater pump 140, a seawater treatment device 150, a buffer tank 160, 1 seawater heat exchanger 170 and a second seawater heat exchanger 180.

The LNG heat exchanger 130 exchanges the LNG supplied from the LNG supply source 110 with the heat required by the customer 120. The LNG supply line 111 through which the LNG flows is connected to the LNG supply source 110, The heat exchanger 130, and the customer 120. The LNG supply source 110 may be a pressure tank for storing LNG, and the customer 120 may be an engine. In the present specification, LNG can be used to encompass both NG, which is a liquid state, and NG, which is a supercritical state, for the sake of convenience.

The LNG heat exchanger 130 is provided on the LNG supply line 111 and exchanges heat with the LNG discharged from the LNG supply source 110. The LNG supplied from the LNG supply source 110 is in a cryogenic state and can be heated by the LNG heat exchanger 130 to be heated to a temperature required by the customer 120. [

The LNG heat exchanger 130 of the present embodiment exchanges heat with the LNG using seawater and the LNG heat exchanger 130 is provided on the seawater supply line 131 to receive the seawater.

The seawater supply line 131 traverses the LNG heat exchanger 130 with the LNG heat exchanger 130 and the seawater pump 140, the seawater treatment apparatus 150, the buffer tank 160 A first seawater heat exchanger 170, an LNG heat exchanger 130 and a second seawater heat exchanger 180. The seawater is supplied from the sea to the LNG heat exchanger 130 to heat-exchange the LNG, To be discharged.

Here, the seawater supply line 131 is provided with a seawater supply valve (not shown), and the supply amount of the seawater can be adjusted according to the adjustment of the opening of the seawater supply valve.

The seawater pump 140 is provided on the seawater supply line 131 and utilizes the pressure to raise seawater supplied from the sea to the LNG heat exchanger 130. The seawater pump 140 of the present embodiment is provided with a controller (not shown) receiving a division signal from a water level sensor (not shown) provided in the buffer tank 160 so that the water level in the buffer tank 160 is not reduced below a predetermined reference value (Not shown).

The seawater treatment device 150 is provided on the seawater supply line 131 between the upstream of the LNG heat exchanger 130 and the downstream of the seawater pump 140 to reduce the salinity of the seawater supplied to the LNG heat exchanger 130. The seawater treatment device 150 receives seawater from the sea and can reduce salinity in seawater by electrodialysis, multi-stage reverse osmosis filtration, and the like. Such a seawater treatment device 150 can use a known technique.

Here, when the LNG heat exchanger 130, the first seawater heat exchanger 170, and the second seawater heat exchanger 180 are formed of metal pipes, in order to prevent corrosion due to salt contained in seawater, 150) reduces the salinity in seawater to below a certain level.

Accordingly, since the LNG can be heat-exchanged by using a general metal pipe without using an expensive pipe to prevent damage due to salt, the manufacturing cost of the heat exchanger 130, 170, or 180 can be reduced.

In addition, the seawater treatment device 150 may add to the seawater any one of the ingredients included in the seawater, for example, a substance that lowers freezing point, in order to prevent seawater heat-exchanged by the LNG from freezing. Thus, the seawater treatment apparatus 150 can reduce the freezing point of the sea water to be processed and reduce the breakage of the seawater supply line 131 after heat exchange with the LNG.

The buffer tank 160 is provided on the seawater supply line 131 downstream of the seawater pump 140 and can receive and store seawater from the seawater pump 140 and may be a general storage tank.

The buffer tank 160 may be provided upstream or downstream of the seawater treatment device 150 and may be provided downstream of the seawater pump 140 to drive the seawater pump 140, The delay due to the driving of the seawater pump 140 can be shortened.

3, when the buffer tank 160 is provided downstream of the seawater treatment device 150, the seawater treated by the seawater treatment device 150 is stored in the buffer tank 160, When the LNG heat exchanger 130 needs seawater to heat-exchange the LNG, it is immediately supplied from the buffer tank 160 and used, so that there is no need to wait for the time for treating the seawater.

The first seawater heat exchanger 170 is provided on the seawater supply line 131 between the seawater treatment device 150 and the LNG heat exchanger 130 to heat-exchange seawater.

The first seawater heat exchanger 170 can be operated when the temperature of the seawater is relatively lower than the summer season in the winter season and the seawater can be heated to sufficiently heat the LNG in the LNG heat exchanger 130. The first seawater heat exchanger 170 may heat seawater using waste heat generated from a generator or other facility.

The second seawater heat exchanger 180 is configured to prevent the temperature of the seawater flowing into the LNG heating system 100 and the temperature of the discharged seawater from being regulated. The second seawater heat exchanger 180 is connected to the LNG heating system The temperature change of the seawater flowing into and out of the storage tank 100 can be made to be equal to or less than the regulated value.

The second seawater heat exchanger 180 is provided on the seawater supply line 131 downstream of the LNG heat exchanger 130 to heat the seawater discharged from the LNG heat exchanger 130 in accordance with the temperature of the sea, And the degree of heating can be made different from season to season. The second seawater heat exchanger 180 may be made of a heater, and the seawater whose temperature is changed by the LNG is made to correspond to the temperature of the sea, thereby reducing the change of the marine environment.

Here, the first bypass line 181 may be provided in the seawater supply line 131, and the first bypass line 181 may branch off from the seawater supply line 131 and merge into the second seawater heat exchanger 180, The second sea water heat exchanger 180 is bypassed to the downstream of the second sea water heat exchanger 180 so that the water can be reheated when the seawater heat-exchanged in the second sea water heat exchanger 180 is not lower than the regulated value of the seawater. Of course, the first bypass line 181 may be bypassed downstream of the second seawater heat exchanger 180 upstream of the second seawater heat exchanger 180.

At this time, a temperature sensor (not shown) is provided in the seawater supply line 131, and a three-way valve (not shown) is provided in the seawater supply line 131 where the first bypass line 181 branches, If the temperature of the seawater is higher than the regulated value, the processed seawater bypasses the upstream of the second seawater heat exchanger 180 for reheating. If the temperature of the heat-exchanged seawater is lower than the regulated value, the first bypass line 181 may be closed to discharge to the sea.

In addition, the seawater supply line 131 of this embodiment can heat-exchange the seawater via the in-ship heat generator 190 downstream of the LNG heat exchanger 130. Here, the heating device 190 may be an equipment in a ship where waste heat (driving heat) is generated by driving, such as an engine and a generator, and a seawater supply line 131 is connected to a heating device 190, respectively.

Here, the second bypass line 191 may be provided in the seawater supply line 131, and the second bypass line 191 may branch off from the seawater supply line 131 and merge in the downstream of the heat generator 190 It can be bypassed to the upstream of the heat generating device 190.

The second bypass line 191 of this embodiment has the same or similar function as the first bypass line 181 and a three-way valve is provided in the seawater supply line 131 at the branch point of the second bypass line 191 A temperature sensor (not shown) is provided upstream of the point where the second bypass line 191 is branched so that the seawater detected by the temperature sensor can be bypassed and reheated or discharged to the sea. The first bypass line 181) can be made with the same principle as sea water. At this time, the heat generator 190 and the second seawater heat exchanger 180 may be provided in parallel by the branched seawater supply line 131.

In addition, the seawater supply line 131 can discharge seawater to the sea via the outer tank 200 at the downstream of the LNG heat exchanger 130. Here, the outer vessel tank 200 is in contact with the sea in the hull, and a space is formed to exchange heat between sea water passing through the sea water supply line 131 and sea water.

At this time, since the outer tank 200 is provided on the side or bottom of the ship, the seawater stored in the outer tank 200 of the ship is heat-exchanged and cooled by the LNG heat exchanger 130, As the thermal equilibrium is established after a certain period of time has elapsed, the processed sea water can be adjusted to the sea water temperature and thus the change of the marine environment can be reduced.

As described above, in this embodiment, since the LNG is heat-exchanged using seawater whose supply amount and discharge are easier than fresh water without using only fresh water with limited storage space and limited supply amount in the ship subject to space restriction, It is not necessary to immediately reuse the heat exchange material cooled by the LNG, and thus the driving of the heater for reheating can be reduced.

1,2,100: LNG heating system 10, 110: LNG supplier
11,111: LNG supply line 20,120: customer demand
30,130: LNG heat exchanger 31,32,131: Seawater supply line
41: first sea water heat exchanger 42: second sea water heat exchanger
43: Third seawater heat exchanger 50: fresh water tank
140: Seawater pump 150: Seawater treatment device
160: Buffer tank 170: First seawater heat exchanger
180: Second Seawater Heat Exchanger 181: First Bypass Line
190: heating device 191: second bypass line
200: tank outside tank

Claims (9)

An LNG supply line from the LNG supplier to the consumer;
An LNG heat exchanger provided on the LNG supply line for exchanging heat with the LNG discharged from the LNG supply source;
A seawater supply line for receiving seawater from the sea, delivering the seawater to the LNG heat exchanger, and discharging seawater heat-exchanged with the LNG to the sea; And
And a seawater treatment unit provided on the seawater supply line upstream of the LNG heat exchanger to reduce salinity of seawater supplied to the LNG heat exchanger. The method according to claim 1,
A seawater pump provided on the seawater supply line for drawing seawater from the sea; And
Further comprising a buffer tank provided on the seawater supply line downstream of the seawater pump for receiving and storing seawater from the seawater pump. 3. The method of claim 2,
Further comprising a first seawater heat exchanger provided on the seawater supply line upstream of the LNG heat exchanger to receive seawater from the buffer tank for heat exchange. The method according to claim 1,
Further comprising a second seawater heat exchanger provided on the seawater supply line downstream of the LNG heat exchanger for exchanging seawater discharged from the LNG heat exchanger in accordance with the temperature of the seawater. 5. The method of claim 4,
Further comprising a first bypass line for branching and joining in the seawater supply line, bypassing the second seawater heat exchanger. The water treatment system according to claim 1,
And the seawater is heat-exchanged via the in-vessel heating device downstream of the LNG heat exchanger. The method according to claim 6,
Further comprising a second bypass line that branches off from the seawater supply line and bypasses the heating device. The water treatment system according to claim 1,
And the seawater is discharged to the sea via the outer tank of the ship downstream of the LNG heat exchanger. 9. The apparatus according to claim 8,
And a space is formed in the hull to contact with the sea to exchange heat between seawater and sea water passing through the seawater supply line.
KR20130120849A 2013-10-10 2013-10-10 A Heat System of Liquefied Natural Gas KR20150042085A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190035357A (en) * 2017-09-26 2019-04-03 삼성중공업 주식회사 LNG regasification system for ship
KR20190128918A (en) * 2018-05-09 2019-11-19 주식회사 포스코 Argon providing system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190035357A (en) * 2017-09-26 2019-04-03 삼성중공업 주식회사 LNG regasification system for ship
KR20190128918A (en) * 2018-05-09 2019-11-19 주식회사 포스코 Argon providing system

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