KR20200022870A - Fuel Supplying System And Method For Ship Using Liquefied Gas - Google Patents

Abstract

Disclosed are a fuel supply system for a liquefied gas propulsion vessel and a method thereof. The fuel supply system for a liquefied gas propulsion vessel of the present invention comprises: a cargo tank which is provided at a vessel to store a liquefied gas to be supplied to an engine of the vessel; a first storage tank which is provided between the cargo tank and the engine to supply the liquefied gas to the engine as fuel; and a second storage tank provided at the downstream of the cargo tank. Here, while the liquefied gas is supplied from the first storage tank to the engine as the fuel, the liquefied gas is supplied from the cargo tank to the second storage tank. When the liquefied gas supplied from the first storage tank to the engine is exhausted, the liquefied gas is supplied from the cargo tank to the first storage tank while the liquefied gas stored in the second storage tank is supplied as the fuel of the engine. Therefore, installation costs are reduced, and LPG can be supplied to the engine in a stable manner.

Description

Fuel Supplying System And Method For Ship Using Liquefied Gas

The present invention relates to a fuel supply system and method for a liquefied gas propulsion vessel, and more particularly, between a cargo tank and an engine provided on the vessel to store liquefied gas to be supplied to the engine of the vessel, the liquefied gas to be supplied to the engine Two storage tanks are provided, the liquefied gas is supplied from the cargo tank to the second storage tank and stored while the liquefied gas is supplied from the first storage tank to the engine. The present invention relates to a fuel supply system and a method for supplying a liquefied gas propulsion vessel that can stably supply engine fuel by supplying liquefied gas stored in a second storage tank as a fuel of an engine.

The consumption of liquefied gas, such as LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas), is increasing worldwide. The liquefied gas is transported in a gas state through a gas pipeline on land or sea, or transported to a distant consumer while stored in a liquefied gas carrier in a liquefied state. Liquefied gas such as LNG or LPG is obtained by cooling natural gas or petroleum gas to cryogenic temperature (approximately -163 ℃ in case of LNG), and its volume is greatly reduced than in gas state, so it is very suitable for long distance transportation by sea.

The liquefaction temperature of petroleum gas is a low temperature of about -42 ℃ normal pressure, LPG is evaporated above the normal pressure -42 ℃, the ship's LPG storage tank is insulated. However, since the external heat is continuously transferred to the LPG, LPG is continuously vaporized in the LPG storage tank during the LPG transport process, and thus, boil-off gas is generated in the LPG storage tank.

In a conventional LPG carrier, when the boil-off gas accumulates in the LPG storage tank, the pressure in the LPG storage tank rises excessively. Used.

However, using an evaporative gas reliquefaction device composed of a suction pump, a reciprocating compressor, a cooler, a condenser, an expansion valve, etc. to condense and reliquefy the evaporated gas, consumes a lot of power, increases operating costs, and increases initial facility investment costs. There is a problem in that it is difficult to secure space on board because a large device must be installed in a limited space of the ship.

Meanwhile, conventional LPG carriers employ a fuel supply system using heavy oil, such as bunker C oil, which is relatively inexpensive as a propulsion fuel for ships, and such heavy oil fuel supply system is an international exhaust gas emission for heavy oil fuel use. Increasing regulations have led to the installation of low sulfur fuel oil tanks (LSHFOs) with low sulfur content, and the need for an environmentally friendly fuel supply system that meets international environmental regulations.

Recently, the application of a fuel supply system that uses LPG or LNG and evaporated gas generated from LPG or LNG as a propulsion fuel is increasing in LPG or LNG carriers, and LNG is also applied to general vessels in addition to LPG or LNG carriers in accordance with international emission regulations. Ships used as propellant fuel are increasing.

An example of a conventional fuel supply system of a ship using LPG as the propellant fuel is schematically shown in FIG.

As shown in FIG. 1, LPG to be supplied as fuel to the engine 70 is supplied from the cargo tank 10 to the fuel storage tank 30 through the pump 20.

LPG supplied to the fuel storage tank 30 is pumped by the pump 40 is supplied to the engine via the high pressure pump 50 and the heat exchanger 60 through the fuel supply line (L1). On the other hand, when some of the LPG supplied to the fuel storage tank is recycled to the fuel storage tank due to over-supply or the fuel consumption rate is changed in accordance with the change in the engine load, it is supplied to the fuel storage tank through the return line (L2).

In such fuel supply system, fuel storage tank should be designed considering the increase of internal pressure due to boil off gas from LPG, flashing LPG fuel recycled through return line, and flashing due to heat generated by pump use. The inventors have found that this may cause an increase in tank capacity.

When the LPG stored in the fuel storage tank is exhausted, the LPG must be pumped and charged from the cargo tank, and the internal pressure of the fuel storage tank can reach up to 19 bar due to the evaporation gas, so that the LPG can be supplied to the high pressure fuel storage tank. In addition to the pump, a feed pump for supplying LPG at a high pressure needs to be additionally installed. Therefore, it has been found that there are problems such as increased installation cost, power consumption, and heat generation due to the operation of the high pressure pump.

In addition, there is a problem in that it takes a long time to supply LPG from the cargo tank after the fuel is exhausted and supply it to the engine again, thereby preventing stable fuel supply to the engine.

The present invention is to solve this problem to reduce the installation cost of the high-pressure pump in the cargo pump to reduce the installation cost, to provide a fuel supply system of the ship that can supply LPG to the engine stably.

According to an aspect of the present invention for solving the above problems, a cargo tank provided in the vessel for storing the liquefied gas to be supplied to the engine of the vessel;

A first storage tank provided between the cargo tank and the engine to supply the liquefied gas to the engine as fuel;

A second storage tank provided downstream of the cargo tank; Including,

While the liquefied gas is supplied from the first storage tank to the engine as fuel, the liquefied gas is supplied from the cargo tank to the second storage tank, and the liquefied gas supplied from the first storage tank to the engine is When exhausted, the liquefied gas is supplied from the cargo tank to the first storage tank while the liquefied gas stored in the second storage tank is supplied to the fuel of the engine, the fuel supply system of the liquefied gas propulsion vessel is characterized in that Is provided.

Preferably, before the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal pressure of the first or second storage tank is lowered so that the liquefied gas is supplied from the cargo tank to a low pressure pump only. Can be.

Preferably, the first low pressure pump is provided in the first storage tank for pumping the liquefied gas to be supplied to the engine; A second low pressure pump provided in the second storage tank and pumping the liquefied gas to be supplied to the engine; A high pressure pump configured to receive and pressurize the liquefied gas from the first or second low pressure pump; And a heat exchanger provided downstream of the high pressure pump to heat the liquefied gas pressurized.

Preferably, the first fuel supply line is provided with the high pressure pump and the heat exchanger is connected to the engine from the first storage tank; A second fuel supply line connected upstream of the high pressure pump from the second storage tank; And a return line connected to the first storage tank from the engine and supplying the liquefied gas supplied to the engine to the first storage tank. It may further include.

Preferably, the first bypass line connected to the upstream of the high pressure pump from the first storage tank; And a second bypass line connected upstream of the high pressure pump from the second storage tank. And further, if the internal pressure of the first or second storage tank is high, the liquefied gas of the first or second storage tank bypasses the first or second low pressure pump to the first or second Can be supplied upstream of the high pressure pump through the bypass line

After the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal temperature of the first or second storage tank is in equilibrium with the atmospheric temperature so that the internal temperature of the first or second storage tank is And when the pressure increases, the liquefied gas of the first or second storage tank bypasses the first or second low pressure pump to be supplied upstream of the high pressure pump through the first or second bypass line. Can be.

According to another aspect of the present invention, by providing a first and a second storage tank between the cargo tank and the engine for storing the liquefied gas to be supplied as fuel to the engine of the ship,

While the liquefied gas is supplied from the first storage tank to the engine as fuel, the liquefied gas is supplied from the cargo tank to the second storage tank, and the liquefied gas supplied from the first storage tank to the engine is When exhausted, the liquefied gas is supplied from the cargo tank to the first storage tank while the liquefied gas stored in the second storage tank is supplied to the fuel of the engine, the fuel supply method of the liquefied gas propulsion vessel, characterized in that Is provided.

Preferably, before the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal pressure of the first or second storage tank is lowered so that the liquefied gas can be supplied from the cargo tank only with a low pressure pump. Can be.

In the present invention, two storage tanks are provided, and one storage tank is operated for supplying engine fuel while the other storage tank is operated for fuel filling. When the liquefied gas in the storage tank is exhausted, it is possible to switch the other storage tank used for fuel filling immediately to supply the engine fuel, thereby stably supplying the engine without delay.

By providing a bypass line in each storage tank and increasing the internal pressure of the storage tank with boil-off gas after equilibrating the storage tank with the atmospheric temperature, the low pressure pump is not operated when operating the storage tank for engine fuel supply. By liquefied gas can be supplied directly to the high pressure pump through the bypass line by the internal pressure of the tank, the power consumption of the low pressure pump in the storage tank can be reduced, thereby reducing the system operating cost.

Figure 1 schematically shows an example of a conventional fuel supply system of a vessel using LPG as the propellant fuel.
Figure 2 schematically shows a fuel supply system of a liquefied gas propulsion ship according to a first embodiment of the present invention.
Figure 3 schematically shows a fuel supply system of a liquefied gas propulsion ship according to a second embodiment of the present invention.
Figure 4 schematically shows a fuel supply system of a liquefied gas propulsion ship according to a third embodiment of the present invention.
5 schematically shows a fuel supply system of a liquefied gas propulsion ship according to a fourth embodiment of the present invention.

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

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, in adding reference numerals to the components of each drawing, it should be noted that the same components are denoted by the same reference numerals as much as possible even if they are displayed on different drawings.

In the embodiments of the present invention described below, the vessel may be any type of vessel in which an engine capable of using liquefied gas as a fuel of a propulsion engine or a fuel of a power generation engine is installed or uses liquefied gas as a fuel. Typical self-propelled vessels such as LPG carriers, LNG carriers, liquid hydrogen carriers, LNG regasification vessels, LNG Floating Production Storage Offloading (FPSO), and LNG Floating Storage Regasification Unit (FSRU). This may include offshore structures that are not capable of propulsion but are floating on the sea. However, in the following embodiment, it will be described taking as an example a liquefied gas carrier.

In addition, the embodiments can be transported by liquefying the gas to a low temperature, and can be applied to a fuel supply system of all kinds of liquefied gas that can generate boil-off gas in a stored state and can be supplied as fuel of an engine. Such liquefied gas is, for example, liquefied petrochemicals such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), Liquefied Ethylene Gas, Liquefied Propylene Gas, etc. It may be a gas. However, embodiments to be described later will be described by taking LPG, which is one of the representative liquefied gases, as an example.

2 is a fuel supply system of a liquefied gas propulsion ship according to a first embodiment of the present invention, Figure 3 is a fuel supply system of a liquefied gas propulsion ship according to a second embodiment of the present invention, Figure 4 of the present invention A fuel supply system of a liquefied gas propulsion ship according to a third embodiment is shown schematically, and FIG. 5 schematically shows a fuel supply system of a liquefied gas propulsion ship according to a fourth embodiment of the present invention.

In the embodiments of the present invention as shown in Figures 2 to 5, between the cargo tank and the engine for storing the liquefied gas to be supplied to the engine of the ship provided on the vessel, two that can store the liquefied gas to be supplied to the engine The storage tanks, that is, the first and second storage tanks T1, T1a, T1b, T1c, T2, T2a, T2b, and T2c are provided.

In particular, in the first to third embodiments shown in FIGS. 2 to 4, the cargo tank CT is supplied from the first storage tanks T1, T1a and T1b to the engine E while the liquefied gas is supplied as fuel. The liquefied gas is supplied to the second storage tanks T2, T2a, and T2b through the supply lines SL, SLa, and SLb. When the liquefied gas of the first storage tank is exhausted, the liquefied gas stored in the second storage tank is stored in the engine. While supplying the fuel, it is configured to supply the liquefied gas from the cargo tank to the first storage tank while the liquefied gas of the second storage tank is supplied to the engine. By configuring two storage tanks as described above, one storage tank can be filled with liquefied gas from the cargo tank to the other while the storage tank is operated for fueling. Even if the liquefied gas is exhausted from the storage tank of the tank, the liquefied gas can be stably supplied to the engine from another storage tank without delay.

First, the system FSS1 of the first embodiment shown in FIG. 2 may be further configured as follows.

The first storage tank is provided with a first low pressure pump 100 for pumping liquefied gas to be supplied to the engine, and the second storage tank is provided with a second low pressure pump 110 for pumping liquefied gas to be supplied to the engine. . The first fuel supply line (FL1) connected to the engine from the first storage tank to the high pressure pump 200 for receiving and pressurizing the liquefied gas from the first or second low pressure pump, and the liquefied gas pressurized downstream of the high pressure pump A heat exchanger 300 for heating is provided. The second fuel supply line FL2 is connected upstream of the high pressure pump from the second storage tank, so that even when the liquefied gas is supplied from the second storage tank to the engine, the first fuel supply line does not need to provide a separate high pressure pump and a heat exchanger. To supply fuel through the high-pressure pump and heat exchanger provided in the. To this end, the second fuel supply line FL2 may be connected to the front of the high pressure pump, that is, to the fuel supply header at the rear end of the first low pressure pump to the first fuel supply line FL1.

Meanwhile, a return line RL may be provided from the engine to the first storage tank, and the liquefied gas supplied to the engine may be supplied to the first storage tank. When the liquefied gas is over-supplied to the engine or when the fuel consumption rate changes due to the load change of the engine, a part of the liquefied gas supplied to the engine is supplied to the first storage tank through the return line for recycling. Can be.

In this embodiment, the engine is supplied with liquefied gas as fuel, for example, it may be a dual fuel engine supplied with LPG and diesel as fuel. In this case, the liquefied gas may be supplied to the engine at about 45 bar and 60 ° C through a high pressure pump and a heat exchanger, and the liquefied gas recycled to the first storage tank through the return line may be supplied to the pressure condition of the first storage tank through the valve. It is reduced in pressure and supplied to the first storage tank.

Meanwhile, in the present embodiment, before the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal pressure of the first or second storage tank is lowered so that the liquefied gas can be supplied only from the cargo tank to the low pressure pump. . That is, by sufficiently lowering the internal pressure of the first or second storage tank, for example, from 1 to 5 bar, prior to liquefied gas filling, even low pressure pumping of the cargo pump 400 in the cargo tank without a separate booster pump. The liquefied gas can be supplied from the cargo tank to the first or second storage tank. The pressure of the first or second storage tank can be lowered, for example, by supplying or venting BOG (Boil Off Gas) in the tank to the BOG treatment means including the GCU provided on board.

That is, while lowering the internal pressure in one of the first or second storage tanks and supplying and filling the liquefied gas from the cargo tank, the other storage tank supplies fuel to the engine. As such, the present embodiment provides two storage tanks, and operates one storage tank for supplying engine fuel while the other storage tank is operated for fuel filling. As soon as the liquefied gas in the storage tanks that have been operated are exhausted, other storage tanks that were operated for refueling can be switched to supply the engine fuel so that the engine can be stably supplied without delay.

The system FSS2 of the second embodiment shown in FIG. 3 has a first bypass line BL1a connected upstream of the high pressure pump from the first storage tank in addition to the system of the first embodiment described above, and a second storage. Second bypass lines BL2a connected to the upstream of the high pressure pump from the tank are respectively provided.

Thus, in this embodiment, when the internal pressure of the first or second storage tank is high, the liquefied gas can be supplied directly upstream of the high pressure pump without being pumped by the first or second low pressure pump, thereby reducing the power consumption of the pump. In addition, it is possible to reduce the generation of heat to reduce the generation of boil-off gas in the tank.

For example, after liquefied gas is supplied from a cargo tank to a first or second storage tank operating for refueling, the valve is closed and the internal temperature of the first or second storage tank is in equilibrium with the ambient temperature so that the first Or the internal temperature and pressure of the second storage tank is increased. After that, when the fuel in the storage tank used for engine fuel supply is exhausted, the storage tank used for fuel filling is converted to the engine fuel supply, and the liquefied gas in the storage tank whose pressure inside the tank is increased is first or second. By bypassing the low pressure pump may be supplied directly upstream of the high pressure pump through the first or second bypass line. When the internal pressure of the storage tank is lowered according to the fuel supply, the liquefied gas may be supplied to the high pressure pump upstream by being pumped to the first or second low pressure pump again.

In this embodiment, a bypass line is provided in each storage tank, and the storage tank is in equilibrium with the atmospheric temperature after filling the fuel to increase the internal pressure of the tank by using boil-off gas. The liquefied gas is supplied to the high pressure pump directly through the bypass line by the internal pressure of the tank without driving the pump. By configuring the system as described above, power consumption according to the driving of the first or second low pressure pump in the storage tank can be reduced, thereby reducing the system operating cost.

In addition to the above-described embodiments, the third embodiment of the present invention (FSS3) shown in FIG. 4 is branched from the first return line RL1b connected to the first storage tank from the engine and the first return line. A second return line RL2b is connected to the second storage tank.

When liquefied gas is supplied to the engine from any one of the first and second storage tanks, the liquefied gas supplied to the engine can be supplied to the other of the first and second storage tanks through the first or second return line. It features.

That is, in the present embodiment, when the liquefied gas is recycled from the engine, the return line is branched to the first and second storage tanks, and when any one of the first and second storage tanks is operated for supplying the engine fuel, the recycled gas is recycled. The liquefied gas is supplied to another storage tank operated for fuel filling, so that the storage tank operated for engine fuel supply can be stably supplied to the engine without being affected by the recycled liquefied gas.

In the storage tank operating for fuel filling, when the liquefied gas is recycled to the return line, the tank may be vented or supplied to the BOG treatment means to maintain the internal pressure of the tank, and as described in the above-described second embodiment, If filling is complete and the valve is closed and in equilibrium with atmospheric temperature, increasing the tank internal pressure, the tank internal pressure may be rapidly increased through the liquefied gas recycled to the return line.

In the fourth embodiment of the present invention (FSS4) illustrated in FIG. 5, the first and second storage tanks are provided as in the above-described embodiments, but unlike the above-described embodiments, the liquefied gas is transferred from the first storage tank to the engine. While being supplied as fuel, the liquefied gas is supplied from the cargo tank to the second storage tank, the liquefied gas is gas-liquid separated from the second storage tank, and the gas is supplied to the vessel's BOG treatment means, and the liquid can be supplied to the first storage tank. It is configured to be.

To this end, a liquid line LLc is further provided to supply the liquid separated from the liquefied gas from the liquefied gas to the first storage tank.

The liquefied gas is supplied from the cargo tank to the second storage tank, and the liquid is separated from the second storage tank to supply liquid to the first storage tank through the liquid line. In the first storage tank, the engine is supplied through the fuel supply line FLc. In addition to the fuel supplied to the liquefied gas through the liquid line can be made to continue to fuel the engine without exhausting the stored liquefied gas. In this case, the first storage tank may be operated for supplying the engine fuel, and the second storage tank may be operated only for the fuel filling. However, when the fuel of the first storage tank is exhausted or maintenance of the first storage tank is required, the second storage tank may be converted to supply the engine fuel.

In the present embodiment, the return line for recirculating a part of the liquefied gas supplied from the engine to the engine may be configured to be connected to the first storage tank as shown in FIG. 5, or alternatively, may be configured to be connected to the second storage tank. have.

As described above, in the present embodiments, two storage tanks, first and second storage tanks, are provided between a cargo tank for storing liquefied gas to be supplied as fuel to an engine of a ship and the engine. Thus, while one storage tank is operated for fueling the engine, liquid is supplied by filling liquefied gas from the cargo tank to the other storage tank or by gas-liquid separation from the other storage tank. By supplying to the tank operated for the purpose, it is possible to stably supply fuel to the engine from the storage tank.

It is apparent to those skilled in the art that the present invention is not limited to the above embodiments, and may be embodied in various modifications or variations without departing from the technical spirit of the present invention. It is.

CT: cargo tank
E: engine
T1, T1a, T1b, T1c: first storage tank
T2, T2a, T2b, T2c: Second Storage Tank
100, 100a, 100b, 100c: first low pressure pump
110, 110a, 110b, 110c: second low pressure pump
200, 200a, 200b, 200c: high pressure pump
300, 300a, 300b, 300c: heat exchanger
400, 400a, 400b, 400c: low pressure pump (cargo pump)
SL, SLa, SLb, SLc: Supply Line
FLc: fuel supply line
FL1, FL1a, FL1b: first fuel supply line
FL2, FL2a, FL2b: second fuel supply line
RL, RLa, RLc: return line
RL1b: first return line
RL2b: second return line
BL1a: first bypass line
BL2a: 2nd bypass line
LLc: Liquid Line

Claims (8)

A cargo tank provided in the ship to store liquefied gas to be supplied to the engine of the ship;
A first storage tank provided between the cargo tank and the engine to supply the liquefied gas to the engine as fuel; And
A second storage tank provided downstream of the cargo tank; Including but not limited to:
While the liquefied gas is supplied from the first storage tank to the engine as fuel, the liquefied gas is supplied from the cargo tank to the second storage tank, and the liquefied gas supplied from the first storage tank to the engine is When exhausted, the liquefied gas from the cargo tank is supplied to the first storage tank while the liquefied gas stored in the second storage tank is supplied to the fuel of the engine, the fuel supply system of the liquefied gas propulsion vessel. The method of claim 1,
Before the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal pressure of the first or second storage tank is lowered so that the liquefied gas can be supplied from the cargo tank only with a low pressure pump. A fuel supply system for a liquefied gas propulsion vessel characterized by the above-mentioned. The method of claim 1,
A first low pressure pump provided in the first storage tank and pumping the liquefied gas to be supplied to the engine;
A second low pressure pump provided in the second storage tank and pumping the liquefied gas to be supplied to the engine;
A high pressure pump configured to receive and pressurize the liquefied gas from the first or second low pressure pump; And
And a heat exchanger provided downstream of the high pressure pump to heat the pressurized liquefied gas. The method of claim 3, wherein
A first fuel supply line provided with the high pressure pump and a heat exchanger and connected to the engine from the first storage tank;
A second fuel supply line connected upstream of the high pressure pump from the second storage tank; And
A return line connected to the first storage tank from the engine and supplying the liquefied gas supplied to the engine to the first storage tank; Fuel supply system of the liquefied gas propulsion ship further comprising. The method of claim 4, wherein
A first bypass line connected upstream of the high pressure pump from the first storage tank; And
A second bypass line connected upstream of the high pressure pump from the second storage tank; More,
When the internal pressure of the first or second storage tank is high, the liquefied gas of the first or second storage tank bypasses the first or second low pressure pump through the first or second bypass line. A fuel supply system of a liquefied gas propulsion vessel, characterized in that can be supplied upstream of the high pressure pump. The method of claim 5,
After the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal temperature of the first or second storage tank is in equilibrium with the atmospheric temperature so that the internal temperature of the first or second storage tank is And when the pressure increases, the liquefied gas of the first or second storage tank bypasses the first or second low pressure pump and is supplied upstream of the high pressure pump through the first or second bypass line. Fuel supply system of a liquefied gas propulsion ship, characterized in that. The first and second storage tanks are provided between the engine and the cargo tank for storing the liquefied gas to be supplied as fuel to the engine of the ship,
While the liquefied gas is supplied from the first storage tank to the engine as fuel, the liquefied gas is supplied from the cargo tank to the second storage tank, and the liquefied gas supplied from the first storage tank to the engine is When exhausted, the liquefied gas from the cargo tank is supplied to the first storage tank while the liquefied gas stored in the second storage tank is supplied to the fuel of the engine, the fuel supply method of the liquefied gas propulsion vessel. The method of claim 7, wherein
Before the liquefied gas is supplied from the cargo tank to the first or second storage tank, the internal pressure of the first or second storage tank is lowered so that the liquefied gas can be supplied from the cargo tank only with a low pressure pump. A fuel supply method of a liquefied gas propulsion ship characterized in that.

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