KR101751850B1

KR101751850B1 - LNG Unloading Method and Fuel Supply Operating System and Method the Same of Liquefied Gas Carrier

Info

Publication number: KR101751850B1
Application number: KR1020150150152A
Authority: KR
Inventors: 장서연
Original assignee: 대우조선해양 주식회사
Priority date: 2015-10-28
Filing date: 2015-10-28
Publication date: 2017-06-28
Also published as: KR20170049145A

Abstract

The present invention relates to a cargo unloading method and a fuel supply operating system and method for a liquefied gas carrier, in particular an LNG carrier, and more particularly to a system for and a method for loading and unloading liquefied gas from a car's fuel tank and cargo tank And a fuel supply operating system and method.
A method of operating a fuel supply system for a ship according to the present invention is a method for supplying a vaporized gas (BOG) generated in a cargo tank storing liquefied gas as fuel for a marine engine and, when unloading the liquefied gas stored in the cargo tank , A liquefied gas is supplementarily supplied from the fuel tank (Fuel Tank) by an amount of evaporation gas supplied from the cargo tank as fuel, and the liquefied gas is supplemented and supplied to the cargo tank, As shown in FIG.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for unloading a liquefied petroleum gas (LNG) carrier and a fuel supply operating system and method for a liquefied gas carrier,

The present invention relates to a cargo unloading method and a fuel supply operating system and method for a liquefied gas carrier, in particular an LNG carrier, and more particularly to a system for and a method for loading and unloading liquefied gas from a car's fuel tank and cargo tank And a fuel supply operating system and method.

In general, the consumption of liquefied gas such as LNG (Liquefied Natural Gas) is rapidly increasing worldwide. The liquefied gas is transported in a gaseous state via land or sea gas piping, or is transported to a distant consumer site stored in a liquefied gas carrier in a liquefied state. Liquefied gas such as LNG is liquefied by cooling natural gas at cryogenic temperatures of about -163 ° C, which is much more voluminous than when it is in a gaseous state, making it well suited for long distance transport through the sea.

Such a liquefied gas carrier carries a liquefied gas storage tank for carrying liquefied gas and operating the sea for unloading the liquefied gas to a land or marine consumer and, for this purpose, capable of withstanding the cryogenic temperature of the liquefied gas.

Since the liquefaction temperature of natural gas is a cryogenic temperature of about -163 ° C at normal pressure, it evaporates even slightly higher than this. For this purpose, the storage tank of the LNG carrier is heat-treated, but the external heat is continuously transferred to the LNG. Therefore, during transport of the LNG by the LNG carrier, the LNG is constantly vaporized in the storage tank, Off Gas, BOG) occurs.

Conventionally, a method of keeping the pressure inside the storage tank at a high level in order to suppress the generation of evaporation gas in the storage tank of the liquefied gas carrier, or discharging the generated evaporation gas to the outside of the storage tank and burning it, The method of returning the fuel, the method of using the evaporative gas as the fuel used in the propulsion engine of the ship, etc. have been used singly or in combination.

Thus, a DF (Dual Fuel) engine mounted on a liquefied gas carrier, particularly an LNG carrier, used evaporative gas generated in the liquefied gas storage tank as fuel. Alternatively, in the case where a separate LNG fuel tank is provided in the LNG carrier, the evaporative gas generated from the liquefied gas storage tank is used as the fuel for the propulsion device, and the rest is returned to the liquefied gas storage tank using the re-liquefying device .

Korean Registered Patent No. 10-1106570 (registered on Jan. 10, 2012)

However, when the evaporated gas generated from the liquefied gas storage tank of the liquefied gas carrier, that is, the cargo tank, is used as the fuel of the engine, there is a problem that the amount shipped to the cargo tank of the liquefied gas carrier is unloaded to the liquefied gas consumer .

That is, the present invention relates to a method for loading and unloading an LNG carrier that can deliver the entire amount of liquefied gas loaded into a cargo tank of a liquefied gas carrier to a freight carrier and steadily and smoothly supplying fuel to the carrier, System, and method.

According to an aspect of the present invention, there is provided a method for supplying a vaporized gas (BOG) generated in a cargo tank storing liquefied gas as fuel for a marine engine, the liquefied gas stored in the cargo tank The cargo tank is supplied with the liquefied gas from the fuel tank by the amount of evaporation gas supplied as fuel from the cargo tank and replenished with the liquefied gas so that an amount of liquefied gas equal to the amount of liquefied gas shipped to the cargo tank A method of operating the fuel supply of the vessel, which can unload the gas to the customer, is provided.

Preferably, the liquefied gas stored in the fuel tank can be supplied as the fuel of the engine when the amount of evaporative gas to be supplied as fuel to the engine is insufficient.

Preferably, the liquefied gas stored in the fuel tank is heat-exchanged with the evaporated gas generated in the cargo tank and supplied to the engine, and the evaporated gas condensed by the heat exchange can be re-supplied to the cargo tank.

Preferably, when the liquefied gas can not be supplied from the fuel tank to the engine, the liquefied gas stored in the cargo tank may be vaporized and supplied as fuel to the engine.

Preferably, after the liquefied gas stored in the cargo tank is unloaded, the liquefied gas remaining in the cargo tank may be supplied as fuel to the engine.

According to another aspect of the present invention, there is provided a cargo unloading method for an LNG carrier including a cargo tank for storing the LNG as a cargo for transporting the LNG to a customer and a fuel tank for storing the LNG as fuel of the engine, When the LNG for cargo stored in the cargo tank is unloaded, the LNG for fuel stored in the fuel tank is supplied to the cargo tank, or the LNG for cargo stored in the cargo tank is supplied to a line for unloading, A method of unloading an LNG carrier is provided.

According to another aspect of the present invention, there is provided a fuel supply operating system for supplying fuel to an engine of a liquefied gas carrier including a cargo tank in which liquefied gas is stored as a cargo, (BOG) as the fuel of the engine; A fuel tank in which the liquefied gas is stored as fuel; And a liquefied gas replenishing line for supplying the liquefied gas from the fuel tank to the cargo tank, wherein when the liquefied gas stored in the cargo tank is unloaded, an amount equal to the amount shipped to the cargo tank by the liquefied gas replenishing line The liquefied gas of the ship can be unloaded.

Preferably, the liquefied fuel supply line further includes a liquefied fuel supply line for supplying liquefied gas from the fuel tank as the fuel of the engine. When the amount of evaporative gas generated in the cargo tank is less than the amount required for the engine, The liquefied gas stored in the fuel tank can be supplied to the engine through the fuel supply line.

Preferably, the system further includes a heat exchanger provided in the liquefied fuel supply line for heating the liquefied gas supplied to the engine, wherein the evaporator gas from the cargo tank and the fuel supplied from the fuel tank to the engine The liquefied gas can be heat-exchanged.

The condenser may further include a condensing gas supply line for heating the liquefied gas in the heat exchanger and re-supplying condensed evaporated gas (LBOG) to the cargo tank.

Preferably, the apparatus may further include a vaporizer provided in the liquefied fuel supply line, for vaporizing the liquefied gas heated in the heat exchanger to supply the fuel as the engine.

Preferably, a liquefied gas supply line for supplying the liquefied gas stored in the cargo tank as the fuel of the engine is provided. The liquefied gas stored in the cargo tank is loaded into the liquefied gas remaining in the cargo tank, And can be supplied as fuel of the engine through a gas supply line.

According to the present invention, since the amount of vaporized gas used as fuel in the cargo tank can be replenished from the fuel tank, the amount of liquefied gas equal to the amount of liquefied gas loaded as cargo on the liquefied gas carrier can be unloaded to the customer.

By heat exchanging the liquefied gas with the evaporated gas, the external heat source necessary to vaporize the liquefied gas can be minimized, thereby saving energy, and the evaporated gas condensed by the heat exchange can be returned to the cargo tank. .

The evaporation gas generated from the cargo tank can be used as fuel and the evaporation gas amount in the cargo tank can be adjusted, so that the ship can be stably operated.

When all the liquefied gas stored as fuel in the fuel tank is exhausted, the liquefied gas stored in the cargo tank can be used as fuel, so that the fuel can be received stably.

1 is a block diagram briefly illustrating a fuel supply operating system of a ship according to an embodiment of the present invention.
2 is a block diagram briefly illustrating a fuel supply operating system of a ship according to another embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects attained by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the present invention, and to the contents of the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same elements are denoted by the same reference numerals even though they are shown in different drawings. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

In this specification, the liquefied gas is present in the gas phase at normal temperature and normal temperature conditions such as natural gas, petroleum gas and ethane gas such as Liquefied Natural Gas (LNG), Liquefied Petroleum Gas (LPG) and Liquefied Ethylene Gas Energy source or raw materials of petrochemical products, etc., it means liquefied gas materials at extremely low temperature for easy storage and transportation. For example, LNG can be present in a liquid phase at about-163 < 0 > C at atmospheric pressure.

In this specification, a cargo tank is used to store cryogenic liquefied gas at a cryogenic temperature for transporting the liquefied gas as a cargo to a demand site either onshore or offshore, , And a fuel tank means an adiabatically treated tank storing the liquefied gas as described above as fuel.

In this specification, the term "liquefied gas carrier" as used herein means a ship or an offshore structure having one or more of the above-described cargo tanks and fuel tanks, each of which has its own propelling capability for transporting the liquefied gas as described above, do.

The liquefied gas stored as a cargo in the cargo tank provided in such a liquefied gas carrier may be the same as the liquefied gas stored as fuel in the fuel tank. For example, the liquefied gas stored as cargo in the cargo tank and the liquefied gas stored as fuel in the fuel tank may all be LNG.

In addition, an engine driven by a liquefied gas or an evaporated gas as fuel from a fuel tank or a cargo tank in a liquefied gas carrier may be a dual fuel engine such as DFDE (Dual Fuel Diesel Electric), which can receive liquefied gas as fuel, Main Engine Electronic Control Gas Injection (ME-GI), Extra Long Stroke Dual Fuel (X-DF) engine, or Gas Turbine. Also, the engine here may be a propulsion engine that generates propulsion of the ship, may be a power generation engine that produces power required for a ship, may include both a main engine or a sub engine, and may be applied anywhere.

FIG. 1 is a block diagram briefly showing a fuel supply operation system of a ship according to an embodiment of the present invention. FIG. 2 is a block diagram of a fuel supply operation system of a ship according to another embodiment of the present invention. . Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 and FIG.

1, a fuel supply operation system for a ship according to an embodiment of the present invention includes a cargo tank 200 that is provided in a liquefied gas carrier and stores liquefied gas as a cargo, And an engine 300 capable of supplying driving force or electric power of the ship by supplying liquefied gas or evaporative gas from the fuel tank 100 and the cargo tank 200 and the fuel tank 100 as fuel.

In an embodiment of the present invention, the liquefied gas stored in the cargo tank 200 and the fuel tank 100 is LNG, and the liquefied gas carrier is an LNG carrier. However, the present invention is not limited thereto.

The fuel supply operation system for a ship according to an embodiment of the present invention may further include an engine 300 for supplying fuel to the engine 300 by supplying a boil off gas (BOG) generated from the cargo tank 200 And a liquefied fuel supply line L2 for supplying the engine 300 with the LNG stored as fuel in the fuel tank 100 from the fuel tank 100. [

That is, according to one embodiment of the present invention, when the laden normal speed of the LNG carrier is used, the evaporative gas generated from the cargo tank 200 can be supplied to the engine of the LNG carrier as fuel, . At this time, the evaporation gas supply line (L1) for supplying the evaporation gas generated from the cargo tank (200) to the engine (300) may further include a compressor (250) for pressurizing the evaporation gas to meet the engine requirement.

When the amount of evaporative gas generated from the cargo tank 200 is less than the amount of fuel required by the engine 300 in accordance with the operation load of the engine 300 and the supply of fuel is insufficient only by the evaporative gas, The liquefied gas is supplied from the fuel tank 100 to the fuel tank 100 via the evaporation gas supply line L1 while the LNG stored in the fuel tank 100 as fuel is supplied to the liquefied fuel supply line L2 to the engine 300 via the first and second valves. Alternatively, the evaporation gas supply line L1 may be closed, and only the LNG stored in the fuel tank 100 may be supplied to the engine 300 through the liquefied fuel supply line L2.

The liquefied fuel supply line L2 is provided with a fuel supply pump 110 for supplying the LNG from the fuel tank 100 to the engine 300, a heat exchanger 150 for converting the LNG into fuel, (170).

In the heat exchanger 150, the LNG supplied from the fuel tank 100 to the engine 300 may be preheated before being vaporized, where the LNG can be preheated by heat exchange with the evaporated gas generated from the cargo tank 200.

At this time, the evaporation gas further includes an evaporation gas branch line L5 branched from the evaporation gas supply line L1 to bypass at least a part of the evaporation gas supplied from the cargo tank 200 to the engine 300, And a line connected directly to the heat exchanger 150 may be further provided from the cargo tank 200 to directly supply the evaporated gas to the heat exchanger 150. [

The evaporated gas preheated by the LNG supplied from the fuel tank 100 to the engine 300 in the heat exchanger 150 can be at least partially condensed and the condensed evaporated gas LBOG flows through the condensed gas supply line L6 And can be re-supplied to the cargo tank 200. At this time, the condensed gas supply line L6 may further include a gas-liquid separator 210 for separating the condensed evaporated gas and the non-condensed gaseous evaporated gas, and the non-condensed gaseous evaporated gas may be separated, And may be supplied again to the line L1.

At this time, the evaporation gas supply line (L1) may further include a second valve (230) for controlling the flow path of the evaporation gas supplied to the heat exchanger (150) at the front end of the heat exchanger (150).

LNG supplied from the fuel tank 100 preheated in the heat exchanger 150 to the engine 300 may be vaporized as natural gas in the vaporizer 170 and supplied to the fuel of the engine 300, May include a Multi-Phase Compressor (not shown) and a Heater (not shown) that pressurize and heat the LNG to vaporize the liquefied gas and convert it into fuel to meet the requirements of the engine 300 have.

According to an embodiment of the present invention, when an emergency situation occurs in which all the LNG stored in the fuel tank 100 is exhausted or the fuel can not be temporarily supplied from the fuel tank 100 to the engine 300, The LNG stored as cargo in the cargo tank 200 through the gas supply line L4 may be supplied as the fuel of the engine 300. [

At this time, the liquefied gas supply line L4 may be a line branched from the liquefied fuel supply line L2, and the LNG may be discharged from the cargo tank 200 to the heat exchanger 150, The fuel can be supplied as the fuel of the engine 300 after being converted into fuel through the vaporizer 170 and the like.

LNG carriers can supply LNG to a customer through a liquefied gas unloading line (not shown) when unloading liquefied gas, that is, LNG stored in the cargo tank 200, at the sea or onshore demand side, The liquefied gas is replenished from the fuel tank 100 to the cargo tank 200 through the liquefied gas supplement line L3 by the evaporation gas and the liquefied gas amount of the cargo tank 200 supplied to the engine 300 as fuel as described above Can supply.

Therefore, according to the embodiment of the present invention, the liquefied gas replenishing line L3 can control the amount of shipment of the liquefied gas from the liquefied gas supply source to the cargo tank 200 and the amount of liquefied gas stored in the cargo tank 200 at the liquefied- The amount of the liquefied gas can be made equal to the amount of the liquefied gas, and the LNG carrier having the same load capacity as the liquefied gas can be provided.

The liquefied gas supplement line L3 may be provided in connection with the cargo tank 200 or may be branched from the cargo line and connected to the cargo line and supplementary supply of liquefied gas may be provided from the cargo tank 200 to the engine 300), the evaporation gas or the liquefied gas is supplied as fuel, and the water level is lowered to a certain level, it may be performed in real time or periodically, or simultaneously with unloading or just before unloading.

The first valve 130 may be provided at a junction where both the liquefied fuel supply line L2, the liquefied gas supplement line L3 and the liquefied gas supply line L4 meet. The first valve 130 is connected to the three- 3-way Vavle).

That is, the control unit 400 controls the fuel tank 100, the level of the cargo tank 200, the flow rate of the evaporation gas supplied from the cargo tank 200 to the engine 300, ) Can be measured singly or in combination to control the three-way valve 130 to control the flow path of the liquefied gas.

An embodiment according to the control of the flow path of the three-way valve 130 is shown in Figs. 1 and 2. Fig.

According to an embodiment of the present invention, after the LNG stored in the cargo tank 200 is unloaded to a land or sea customer, or when the cargo tank is seagoing ballast, the liquefied gas supply line L4 is used to supply the cargo tank The liquefied gas remaining in the lower portion of the engine 200 may be sucked and supplied to the engine 300 as fuel.

As described above, according to the present invention, the evaporation gas continuously generated in the cargo tank 200 is utilized as the fuel of the engine 300, and when the evaporation gas amount is insufficient, the liquefied gas stored in the fuel tank 100 is supplied to the engine The fuel can be supplied stably to the cargo tank 200 from the fuel tank 100 by an amount supplied to the fuel of the engine 300. As a result, The same capability can be provided.

A heat source for vaporizing the liquefied gas by heat-exchanging the liquefied gas supplied from the fuel tank 100 to the engine 300 and the evaporated gas generated in the cargo tank 200 and a heat source for liquefying the evaporated gas And the like can be saved.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or scope of the invention as defined in the appended claims. . Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and the present invention is not limited to the above description, and may be modified within the scope of the appended claims and equivalents thereof.

100: Fuel tank
110: fuel supply pump
130: first valve
150: heat exchanger
170: vaporizer
200: Cargo tank
210: gas-liquid separator
230: second valve
250: Compressor
300: engine
400:
L1: Evaporative gas supply line
L2: liquefied fuel supply line
L3: Liquefied gas supplement line
L4: liquefied gas supply line
L5: Evaporative gas branch line
L6: Condensate gas supply line

Claims

(BOG) generated from the cargo tank storing the liquefied gas is supplied as the fuel of the marine engine,
When the liquefied gas stored in the cargo tank is unloaded,
The liquefied gas is supplied from the fuel tank (fuel tank) storing the liquefied gas by the amount of evaporation gas supplied from the cargo tank as fuel,
By supplying the liquefied gas supplementarily, the liquefied gas in an amount equal to the amount of liquefied gas shipped in the cargo tank can be unloaded to the customer,
When the amount of evaporative gas to be supplied as fuel to the engine is insufficient,
Supplying the liquefied gas stored in the fuel tank as fuel of the engine,
The liquefied gas stored in the fuel tank is heat-exchanged with the evaporated gas generated in the cargo tank and supplied to the engine,
And the evaporated gas condensed by the heat exchange is re-supplied to the cargo tank.

delete

The method according to claim 1,
When the liquefied gas can not be supplied from the fuel tank to the engine,
Wherein the liquefied gas stored in the cargo tank is vaporized and supplied as fuel to the engine.

The method of claim 4,
And the liquefied gas remaining in the cargo tank is supplied to the engine as fuel after unloading the liquefied gas stored in the cargo tank.

delete

A fuel supply operating system for supplying fuel to an engine of a liquefied gas carrier including a cargo tank in which liquefied gas is stored as a cargo,
An evaporation gas supply line for supplying evaporation gas (BOG) generated from the cargo tank as fuel of the engine;
A fuel tank in which the liquefied gas is stored as fuel; And
And a liquefied gas replenishing line for supplying liquefied gas from the fuel tank to the cargo tank,
Upon unloading the liquefied gas stored in the cargo tank,
The same amount of liquefied gas as the amount shipped to the cargo tank can be unloaded by the liquefied gas supplement line,
And a liquefied fuel supply line for supplying liquefied gas from the fuel tank as fuel of the engine,
When the amount of evaporative gas generated in the cargo tank is less than the amount of fuel required for the engine,
Supplying the liquefied gas stored in the fuel tank to the engine through the liquefied fuel supply line,
And a heat exchanger provided in the liquefied fuel supply line for heating the liquefied gas supplied to the engine,
Wherein the heat exchanger exchanges heat between evaporative gas generated from the cargo tank and liquefied gas supplied from the fuel tank to the engine.

delete

The method of claim 7,
And a condensed gas supply line for heating the liquefied gas in the heat exchanger and then re-supplying the condensed evaporated gas (LBOG) to the cargo tank.

The method of claim 7,
And a vaporizer provided in the liquefied fuel supply line for vaporizing the liquefied gas heated in the heat exchanger to supply the fuel as fuel to the engine.

The method of claim 7,
And a liquefied gas supply line for supplying liquefied gas stored in the cargo tank as fuel of the engine,
And the liquefied gas remaining in the cargo tank can be supplied as fuel of the engine through the liquefied gas supply line after unloading the liquefied gas stored in the cargo tank.