KR20190105841A - Liquefied Petroleum Gas Fueled Ship and Fuel Supply Method of LPG Fueled Ship - Google Patents

Abstract

The present invention relates to a vessel using LPG as fuel and a method of effectively supplying LPG fuel to an LPG fuel engine of the vessel using LPG as fuel. According to the present invention, the LPG fuel vessel includes: an LPG storage tank storing liquified petroleum gas (LPG); an LPG fuel engine using LPG as fuel; a reliquefication system re-liquefying evaporation gas, which is produced from the LPG storage tank, to collect the gas into the LPG storage tank; a heat exchanger exchanging heat between the LPG to be supplied to the LPG fuel engine and the evaporation gas re-liquefied in the reliquefication system to collect cold and heat from the LPG; and an after heater heating the LPG, of which cold and heat have been collected in the heat exchanger, at a temperature demanded by the LPG fuel engine.

Description

Liquefied Petroleum Gas Fueled Ship and Fuel Supply Method of LPG Fueled Ship}

The present invention relates to a method of effectively supplying LPG fuel to an LPG fuel engine of a vessel using LPG as fuel and a vessel using LPG as fuel.

According to the International Maritime Organization (IMO) Air Pollution Control Agreement, since January 2015, the upper limit of global sulfur emissions of ships operating in Emission Control Area (ECA) such as North Sea and Baltic Sea Cap is regulated at 0.1%. Due to the stricter regulations on sulfur oxides in ships, we recommend the use of low sulfur fuel, which is about twice the price of bunker C oil (3.5% sulfur content) .For example, ships operating ECA are Marine Gases (MGO). Only fuel oils containing less than 0.1% sulfur, such as oil, are allowed.

Meanwhile, in some parts of the world except for the ECA, the regulations will be tightened after 2020. In general, except for the ECA, the regulation of fuel sulfur was 3.5% in January 2012, and 0.5% in 2020. It will be strengthened.

As a countermeasure to meet the enhanced sulfur oxide (SO _X ) emission regulations, it is recommended to use fuel oil, which is a low-cost but high sulfur high-resistance fuel oil, with a sulfur oxide removal device to limit Purify and discharge, or use distillate fuel oil, which is expensive but low sulfur fuel oil with less than 0.5% sulfur, as fuel, or use natural gas or fuel cell There is a way.

As such, international regulations for preventing air pollution have been strengthened, leading to changes in marine fuels, and increasing demand for clean fuels containing no sulfur. Among them, methane-based natural gas is being applied as the future fuel of representative ships, and liquefied petroleum gas (LPG) is also emerging as an effective marine propulsion fuel.

LPG is the first and most produced byproduct of petroleum refining and liquefaction of natural gas. LPG's offshore cargo volume is increasing, and LPG carriers (LPG carriers, LPG tankers) are growing as LPG infrastructure grows globally. Demand is expected to be higher.

The propulsion system of a conventional LPG carrier consists of a diesel engine using oil fuel, such as diesel, heavy fuel oil (HFO) or marine diesel oil (MDO).

However, in LPG carriers, LPG is already stored in the LPG storage tank as a cargo, so if a part of the LPG cargo is used as a propulsion fuel for the propulsion of the vessel, it can not only satisfy the environmental regulations as an eco-friendly vessel, but also fuel costs. It will also ease the burden.

Accordingly, the present invention, LPG fuel ship using LPG as a propulsion fuel by mounting the LPG fuel engine in addition to the LPG carrier transporting LPG carriers as well as the LPG carrier ships, LPG fuel ships LPG fuel engine in LPG fuel engine It is an object of the present invention to provide a fuel supply method of the LPG fuel vessel that can effectively supply the.

According to an aspect of the present invention for achieving the above object, LPG storage tank for storing LPG (Liquefied Petroleum Gas); LPG fuel engines using LPG as fuel; A reliquefaction system for reliquefying the boil-off gas generated in the LPG storage tank to recover the LPG storage tank; A heat exchanger for recovering cold heat of the LPG by heat-exchanging the LPG to be supplied to the LPG fuel engine and the boil-off gas liquefied in the reliquefaction system; And an after-heater for heating the LPG recovered from the cold heat in the heat exchanger to a temperature required by the LPG fuel engine.

Preferably, the high-pressure pump for compressing the LPG recovered from the cold heat in the heat exchanger to the pressure required by the LPG fuel engine; may further include a.

Preferably, the pressure required by the LPG fuel engine may be 45 bar to 55 bar.

Preferably, the minimum temperature required by the LPG fuel engine is 20 ° C to 25 ° C, and the after heater may heat the LPG to 50 ° C to 60 ° C.

Preferably, the feed pump which is provided in the LPG storage tank, for discharging the LPG stored in the LPG storage tank to the outside of the LPG storage tank; And a service tank storing LPG preheated in the heat exchanger after being discharged by the feed pump, and adjusting a flow rate of the LPG supplied to the high pressure pump.

Preferably, a recovery line connecting the LPG fuel engine and the service tank and flowing gaseous gas from the LPG fuel engine to the service tank is further included, and is transferred to the service tank through the recovery line. The gas may be condensed by cold heat of LPG stored in the service tank.

Preferably, the boil-off gas generated in the service tank is transferred to the re-liquefaction system, the re-liquefaction system to re-liquefy the boil-off gas generated in the LPG storage tank and the boil-off gas generated in the service tank LPG storage Can be recovered in a tank.

Preferably, the reliquefaction system, the evaporation gas compressor for compressing the boil off gas; And an intercooler for cooling the boil-off gas whose temperature has risen by the compression.

Preferably, the re-liquefaction system, the first expansion means for cooling the evaporated gas is reliquefied and recovered to the LPG storage tank by reduced pressure; And an evaporation gas branching line for flowing the evaporated gas cooled by the first expansion means to the intercooler. The evaporated gas cooled by the first expansion means may be used as a refrigerant in the intercooler.

Preferably, the reliquefaction system, the condenser for condensing the compressed boil-off gas compressed in the boil-off gas compressor; And an evaporation gas line connecting the condenser and the intercooler to flow the evaporated gas condensed in the condenser to the intercooler, wherein the evaporation gas branching line is branched from the evaporative gas line. In the intercooler, the boil-off gas whose temperature rises by the compression and the remaining un-expanded boil-off gas may be cooled by cooling heat to the boil-off gas cooled by the first expansion means.

Preferably, the reliquefaction system further comprises a second expansion means for depressurizing the reliquefaction evaporated gas cooled in the intercooler or the reliquefaction evaporated gas cooled in the intercooler and the heat exchanger to the internal pressure of the LPG storage tank. can do.

Preferably, the LPG fuel engine may be a ME-LGIP engine.

According to another aspect of the present invention for achieving the above object, by supplying the LPG stored in the LPG storage tank as the fuel of the engine, the boil-off gas generated by LPG natural vaporization is recovered to LPG storage tank, Heat-exchanging the LPG to be supplied as fuel for the engine and the reliquefied boil-off gas recovered to the LPG storage tank; Compressing the LPG heated by the heat exchange to a pressure required by the engine; And further heating the compressed LPG to a temperature required by the engine.

Preferably, operating the feed pump to discharge the LPG to be heat-exchanged with the reliquefied evaporated gas from the LPG storage tank; And supplying LPG heated by heat exchange with the reliquefaction evaporated gas to a service tank, by discharging LPG from the service tank and compressing the LPG to a pressure required by the engine, thereby supplying LPG to the engine. The flow rate can be adjusted.

Preferably, the step of compressing the boil-off gas in multiple stages; Condensing the compressed boil-off gas; Cooling the condensation boil off gas; And reducing the cooled reliquefaction evaporated gas to an internal pressure of the LPG storage tank.

Preferably, the step of compressing the boil-off gas in a multi-stage comprises: cooling the boil-off gas whose temperature has risen by compression; and cooling the condensed boil-off gas comprises at least a portion of the condensed boil-off gas. Cooling by expansion; including, by supplying the expanded evaporation gas cooled by the expansion by injection may be utilized as a refrigerant for cooling the evaporation gas and the remaining condensation evaporation gas temperature is increased by the compression. have.

Preferably, the cooled reliquefied boil-off gas may be exchanged with the LPG to be supplied as the fuel of the engine, further cooled, and decompressed to recover the LPG storage tank.

According to the LPG fuel vessel and the fuel supply method according to the present invention, LPG can be used as the propulsion fuel of the vessel, in particular, by using the LPG cargo stored in the LPG storage tank of the LPG carrier ship as the fuel of the engine, It is possible to provide an eco-friendly vessel that can save energy while satisfying the discharge regulation of the vessel.

In addition, by reliquefying and recovering the boil-off gas generated in the LPG storage tank, it is possible to prevent excessive increase in the internal pressure of the LPG storage tank by the boil-off gas to improve the storage and safety of the LPG storage tank In addition, it is possible to reduce the cost separately to remove the boil-off gas.

In addition, by cooling by using the cold heat of LPG to supply the re-liquefied evaporated gas as fuel, it is possible to reduce the duty of the after-heater for adjusting the LPG to the required temperature of the LPG fuel engine, and reduce the energy consumption have.

In addition, by recovering the cold heat of the LPG to be supplied as fuel to cool the reliquefied evaporated gas, it is possible to reduce the amount of flash gas generated to reduce the vapor fraction of the reliquefied evaporated gas recovered. Therefore, the reliquefaction efficiency of the boil-off gas can be increased.

In addition, by increasing the reliquefaction efficiency of the boil-off gas, the amount of boil-off boil-off gas can be reduced and economical, it is possible to increase the reliability of the LPG carrier.

In addition, when supplying the LPG stored in the LPG storage tank to the service tank using a pump provided for unloading the LPG cargo, LPG fuel engine without having to provide a separate pump for fueling the LPG stored in the LPG storage tank To control the amount of LPG fuel supplied.

1 is a configuration diagram schematically showing an LPG fuel supply system.
FIG. 2 is a configuration diagram schematically illustrating an LPG fuel supply system and a reliquefaction system of an LPG fuel vessel according to a first embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating an LPG fuel supply system and a reliquefaction system of an LPG fuel vessel according to a second embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating an LPG fuel supply system and a reliquefaction system of an LPG fuel vessel according to a third 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 reference numerals are denoted by the same reference numerals as much as possible even if displayed on different drawings. In addition, the following examples may be modified in many different forms, and the scope of the present invention is not limited to the following examples.

The embodiments of the present invention described below may be applied to a ship, and in particular, an engine using LPG (Liquefied Petroleum Gas) as a fuel is used as a propulsion engine and / or a power generation engine, and LPG is used as a cargo and / or It can be applied to ships equipped with LPG storage tanks which store as fuel. In the present specification, LPG carriers (LPG Carrier, LPG Tanker) as a vessel will be described as an example, but is not limited thereto, and may be applied to various vessels such as general passenger ships or container ships.

LPG is a mixture in which propane, butane, and the like are mixed. The composition may vary slightly depending on the production site. In the present specification, LPG will be described by taking propane as a main component as an example, and thus, LPG in the present specification may mean propane. However, the composition of the LPG is not limited.

In addition, the LPG fuel engine in the present specification will be described taking as an example ME-LGIP (MAN Electronic-Liquid Gas Injection LPG). However, the present invention is not limited thereto, and any engine that can be driven by using LPG as a fuel may be applied in the same or within a changeable range.

The liquid gas injection (ME-LGI) engine developed by the engine manufacturer MAN Diesel & Turbo can use liquid gas fuel. The ME-LGI engine is a high-pressure liquid gas injection dual-fuel engine, which is a low flashpoint liquid (LFL) such as methanol, ethanol, dimethylether and LPG. ) Can be used as fuel and is driven by a diesel cycle.

Unlike ME-GI engines, where fuel is injected into the gas phase, ME-LGI engines are dual fuel engines for low flash point liquid fuels. ME-LGI engines are designed to successfully overcome the application of fuels with low cetane numbers, such as methanol, especially for poor self-ignition quality.

The ME-LGI engine is a liquid gas injection engine (ME-LGIM), a liquid gas injection engine designed for methanol operation to use methanol fuel, and a liquid gas injection engine designed for LPG operation to use LPG as fuel. It is divided into ME-LGIP, and the design structure, fuel supply system and method should be changed according to the characteristics of fuel.

In the embodiments described below, the LPG fuel engine will be described taking as an example that ME-LGIP is applied.

1 is a schematic view showing the basic concept of the LPG fuel supply system, Figures 2 to 4 briefly shows the LPG fuel supply system and the reliquefaction system of the LPG fuel ship according to an embodiment of the present invention It is a schematic diagram. Hereinafter, a fuel supply method of an LPG fuel vessel and an LPG fuel vessel according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 to 4.

Referring first to Figure 1, LPG fuel supply system, LPG storage tank 10 for storing LPG; LPG fuel engine using LPG stored in the LPG storage tank 10 as a fuel; It includes; and LPG fuel supply system for fueling the LPG stored in the LPG storage tank 10 to the LPG fuel engine.

Inside the LPG storage tank 10, a fuel pump 11 for pressurizing the LPG stored in the LPG storage tank 10 to supply the LPG fuel supply system; may be provided.

The LPG fuel supply system adjusts the amount of LPG supplied by the fuel pump 11 to temporarily store the service tank 22 for supplying the LPG fuel engine as much as the amount of fuel required for the LPG fuel engine to drive the LPG fuel engine. ; A fuel booster pump 23 for compressing the LPG supplied from the service tank 22 to a pressure required by the LPG fuel engine; And an after heater 25 for heating the LPG compressed by the fuel booster pump 23 to a temperature required by the LPG fuel engine.

In the LPG fuel supply system, vaporized gas such as boil-off gas (BOG) generated during the LPG fueling process may be safely released into the atmosphere through a vent mast (not shown).

The temperature of the LPG stored in the LPG storage tank 10 may be about -55 ℃ to -45 ℃.

The pressure of the LPG fuel required by the LPG fuel engine may be about 52 bar, for example about 48 bar to 52 bar for the ME-LGIP engine, and the temperature may be about 25 ° to 55 ° C.

That is, the LPG stored in the LPG storage tank 10 is temporarily stored in the service tank 22, compressed by the fuel booster pump 23, and supplied to the LPG fuel engine, which is compressed by the fuel booster pump 23. The temperature of the LPG is considerably lower than about 25 ° C. which is the minimum temperature required for LPG fuel engines. Thus, the heating duty assigned to the after heater 25 at this time is quite high. According to an embodiment of the present invention to be described later, such a problem can be solved.

2, the LPG fuel vessel according to the first embodiment of the present invention, LPG storage tank 100 for storing LPG; LPG fuel engine E using LPG stored in LPG storage tank 100 as fuel; LPG fuel supply system for converting the LPG stored in the LPG storage tank 100 to the LPG fuel engine E; And an evaporation gas treatment system for treating boil off gas (BOG) generated in the LPG storage tank 100.

In FIG. 2, for example, only one LPG storage tank 100 is installed. However, one or more LPG storage tanks 100 may be installed in the LPG fuel vessel.

In addition, the LPG storage tank 100 may be a cargo tank for storing the LPG for cargo, or may be a fuel tank for storing the LPG for fuel.

In addition, the LPG storage tank 100, the feed pump 110 to pressurize the LPG stored in the LPG storage tank 100 to the LPG fuel supply system; may be provided. The feed pump 110 may be a capacity fixed semi-submersible pump.

The feed pump 110 of the present embodiment may be a cargo pump installed in the LPG storage tank 100 and provided for unloading the LPG, or may be a fuel pump provided separately from the cargo pump, but is not limited thereto. Do not.

LPG stored in the LPG storage tank 100 of the present embodiment may be in a liquid state of about -55 ℃ to about -45 ℃. The LPG storage tank 100 may be insulated so that the low temperature LPG maintains a liquid state.

The LPG fuel supply system of this embodiment adjusts the amount of LPG supplied by the feed pump 110 to supply LPG as much as the amount of fuel required to drive the LPG fuel engine E to the LPG fuel engine E. Service tank 220 to temporarily store in order to; A high pressure pump 230 for compressing LPG to be supplied from the service tank 220 to the LPG fuel engine E to a pressure required by the LPG fuel engine E; A filter 240 for removing foreign substances from the LPG fuel to be supplied to the LPG fuel engine E; An after heater 250 for heating the compressed LPG compressed by the high pressure pump 230 to a temperature required by the LPG fuel engine E; And a heat exchanger 210a for preheating LPG to be supplied as fuel by heat exchange with the reliquefaction evaporated gas.

According to the present embodiment, the LPG storage tank 100 is connected to the LPG fuel supply system and the LPG fuel engine E, and the LPG passes from the LPG storage tank 100 to the LPG fuel engine E through the LPG fuel supply system. Flowing fuel supply line (FL); may further include.

That is, the LPG stored in the LPG storage tank 100 is pressurized by the feed pump 110, and the heat exchanger 210a, the service tank 220, the high pressure pump 230, and the filter along the fuel supply line FL. LPG fuel that is fueled while passing through the 240 and the after heater 250 and that satisfies the pressure and temperature conditions required by the LPG fuel engine E is supplied as the fuel of the LPG fuel engine E.

The pressure of the LPG fuel required by the LPG fuel engine E of the present embodiment may be about 40 bar to 70 bar, or about 45 bar to 55 bar, and preferably about 48 bar to 52 bar.

In addition, the temperature of the LPG fuel required by the LPG fuel engine E of the present embodiment may be about 20 ° C to about 60 ° C, preferably about 25 ° C to 55 ° C. The minimum temperature of the LPG fuel required by the LPG fuel engine E of the present embodiment may be about 20 ° C to 30 ° C.

The heat exchanger 210a of this embodiment heats LPG to be supplied to the LPG fuel engine E primarily by heat exchange. The heat medium for recovering the cold heat of LPG in the heat exchanger 210a of this embodiment is a reliquefaction evaporated gas which is liquefied in the reliquefaction system 300 described later and recovered to the LPG storage tank 100.

The temperature of the reliquefied boil-off gas that exchanges heat with the LPG in the heat exchanger 210a may be 50 ° C. or less or 40 ° C. or less or 35 ° C. or less. When the reliquefaction evaporated gas heat exchanged with LPG in the heat exchanger 210a is propane, the temperature may be about −25 ° C. to 0 ° C., and may be about 10 ° C. to 50 ° C. for butane.

The high pressure pump 230 of the present embodiment provides a pressure required by the LPG fuel engine E to supply LPG to be supplied from the service tank 220 to the LPG fuel engine E, that is, about 40 bar to 70 bar or about 45 degrees. bar to 55 bar, preferably about 48 bar to 52 bar.

The after heater 250 of the present embodiment can heat the compressed LPG compressed by the high pressure pump 230 to a temperature required by the LPG fuel engine E, that is, about 25 ° C to 55 ° C. In particular, the after heater 250 may heat the compressed LPG compressed by the high pressure pump 230 to a temperature higher than the minimum temperature required by the LPG fuel engine E.

The LPG stored in the LPG storage tank 100 at about −55 ° C. to −45 ° C. is primarily heated in the heat exchanger 210a, and the LPG preheated in the heat exchanger 210a is approximately at high pressure pump 230. Compressed to 48 bar to 52 bar, the preheated and compressed LPG is heated to about 25 ° C to 55 ° C in the after heater 250.

According to the present embodiment, by preheating the LPG by recovering the cold heat of the LPG to be supplied to the LPG fuel engine E from the heat exchanger 210a, the heat load of the after heater 250 can be reduced, and the LPG fuel engine E It is possible to heat the compressed LPG above the minimum temperature required by), and to save energy for heating the compressed LPG to the temperature required by the LPG fuel engine (E).

The vaporized gas generated in the LPG fuel supply system can be recovered by supplying to the reliquefaction system 300 which will be described later and reliquefying.

In addition, the boil-off gas generated in the LPG fuel engine (E) or the LPG used in the LPG fuel engine (E) and remaining, the recovery line (SL) connecting the LPG fuel engine (E) and the service tank 220; May be recovered to the service tank 220.

In the recovery line SL, liquid LPG or gaseous LPG may be recovered from the LPG fuel engine E to the service tank 220.

The boil-off gas recovered to the service tank 220 through the recovery line SL may be condensed by cold heat of LPG stored in the service tank 220.

On the other hand, since the liquefaction temperature of petroleum gas is a low temperature of about -42 ℃ at normal pressure, LPG is evaporated even if the temperature is only slightly higher than about -42 ℃ at normal pressure. Even though the LPG storage tank 100 of the present embodiment is insulated, the external heat is continuously transmitted to the LPG in the LPG storage tank 100, so that LPG is continuously in the LPG storage tank 100 while transporting the LPG. Boil-off gas (BOG) may be generated by natural vaporization.

LPG storage tank 100 may also be designed to withstand a certain level of pressure rise due to continuously generated boil-off gas. However, if the boil-off gas generated in the LPG storage tank 100 continues to accumulate, the pressure in the LPG storage tank 100 is excessively increased, which is dangerous. When the pressure rises above the set value of the safety valve, the safety valve It can be automatically opened and controlled to automatically discharge the boil-off gas.

The LPG fuel vessel according to the present embodiment is provided with an evaporative gas treatment system for treating the evaporated gas discharged from the LPG storage tank 100. The boil-off gas treatment system of this embodiment may include a re-liquefaction system 300 for re-liquefying the boil-off gas to recover the LPG storage tank. Process elements of the reliquefaction system 300 to be described later are not limited thereto, and may be changed according to operating conditions in a specific process method.

In addition, the boil-off gas treatment system of the present embodiment may process not only boil-off gas discharged from the LPG storage tank 100 but also boil-off gas generated in the service tank 220 although not shown in the drawing.

That is, the boil-off gas generated in the service tank 220 may also be transferred to the re-liquefaction system 300 to be re-liquefied and recovered. Hereinafter, the boil-off gas refers to the boil-off gas generated in the LPG storage tank 100 as well. The concept may also include boil-off gas generated in the service tank 220.

The reliquefaction system 300 of the present embodiment includes an evaporative gas compressor 320 for compressing the evaporated gas; And a condenser 330 for condensing the compressed boil-off gas compressed by the boil-off gas compressor 320.

In addition, the front end of the boil-off gas compressor 320, the knockout drum 310 for removing liquid components such as droplets and mist contained in the boil-off gas introduced into the boil-off gas compressor 320 from the LPG storage tank 100; It may be further provided.

By providing the knockout drum 310 at the front end of the boil-off gas compressor 320, the liquid component included in the boil-off gas supplied to the boil-off gas compressor 320 can be removed. By removing the liquid component contained in the boil-off gas supplied to the boil-off gas compressor 320, when the liquid component is mixed into the boil-off gas compressor 320, problems such as damage to the compressor can be prevented.

The boil-off gas compressor 320 of the present embodiment may be a multi-stage compressor that compresses the boil-off gas in multiple stages. In this embodiment, the boil-off gas compressor 320 includes three compressors, such as a first compressor, a second compressor, and a third compressor, which sequentially compress the boil-off gas, and is a three-stage compressor that compresses the boil-off gas in three stages. This will be described as an example.

In this embodiment, the boil-off gas compressor 320 compresses the boil-off gas to about 20 to 30 bar in three stages.

In addition, the boil-off gas compressor 320 of the present embodiment may be a reciprocating compressor.

At the rear end of the first compressor of the boil-off gas compressor 320 of the present embodiment, an intercooler 360 for cooling the boil-off gas whose temperature has risen by compression in the first compressor may be provided.

In the intercooler 360, the boil-off gas compressed in one step is cooled by the cold heat of the re-liquefied boil-off gas described later. The boil-off gas cooled in the intercooler 360 is introduced into the second compressor.

Inside the intercooler 360, a filter member (not shown) may be installed to filter liquid components of the boil-off gas cooled by the intercooler 360 and supplied to the second compressor. By filtering the liquid component by the filter member, only the boil-off gas in the gaseous state of the boil-off gas cooled in the intercooler 360 may be introduced into the second compressor.

The condenser 330 of the present embodiment condenses the compressed boil-off gas compressed by the boil-off gas compressor 320 by heat exchange. In the condenser 330 of the present embodiment, the boil-off gas may be in a saturated condition, and the whole amount may be condensed in a liquid state.

Seawater (sw) may be used as a refrigerant that condenses the compressed boil-off gas in the condenser 330.

According to the present embodiment, the LPG storage tank 100, the knockout drum 310, the boil-off gas compressor 320, the intercooler 360, and the condenser 330 are connected, and the boil-off gas discharged from the LPG storage tank 100. It is further included; boil-off gas line (BL) for providing a path that is re-liquefied to be recovered to the LPG storage tank (100).

The temperature of the boil-off gas generated in the LPG storage tank 100 may be about -50 ℃ to -40 ℃.

The boil-off gas discharged from the LPG storage tank 100 flows along the boil-off gas line BL and is compressed in the boil-off gas compressor 320, condensed in the condenser 330, and liquefied in its entirety, and discharged from the condenser 330. The temperature of the liquid evaporated gas may be about 40 ° C.

By compressing the boil-off gas at high pressure in the boil-off gas compressor 320, the boil-off gas may be liquefied in the condenser 330.

The reliquefaction system of this embodiment further includes a receiver 340 for receiving the condensation evaporation gas discharged from the condenser 330.

The receiver 340 temporarily stores the condensed evaporation gas in a saturated state discharged from the condenser 330, stabilizes the flow of the evaporated gas, and adjusts the flow rate of the evaporated gas recovered in the liquid state to the LPG storage tank 100. It may be to be installed to.

The condensation boil-off gas stored in the receiver 340 may be supplied to the intercooler 360.

In addition, according to the present embodiment, as shown in FIG. 2, the boil-off gas branch line BL1 branched from the boil-off gas line BL connecting the receiver 340 and the intercooler 360; And first expansion means 350 installed at the boil-off gas branch line BL1 to expand the condensed boil-off gas.

That is, some of the condensed boil-off gas supplied from the receiver 340 to the intercooler 360 branches to the boil-off gas branch line BL1, and the boil-off gas branched to the boil-off gas branch line BL1 is the first expansion means 350. The evaporation gas whose temperature is lowered by decompression and the temperature is lowered by depressurizing may be used as a refrigerant for cooling the evaporation gas in the intercooler 360.

In addition, the interior of the intercooler 360, an injection unit (not shown) for supplying the expanded evaporation gas injection into the intercooler 360; may be provided, the expansion evaporation gas is injected into the intercooler 360 Can be supplied.

In this case, the injection unit may be located below the filter member described above. The filter member may play a role of preventing expansion of the expanded boil-off gas supplied into the second compressor.

The remaining condensed boil-off gas branched to the boil-off gas branch line BL1 is supplied to the intercooler 360 along the boil-off gas line BL. In this case, the inlet through which the condensation evaporation gas is supplied to the intercooler 360 may be located below the injection unit.

In the intercooler 360, the first stage compressed boil-off gas and the remaining uncondensed condensed boil-off gas that are compressed in the first compressor and supplied to the second compressor are cooled by the cold heat of the expanded boil-off gas.

The condensation evaporation gas flows along the heat exchanger tube installed in the intercooler 360, and may be cooled by the cooling heat of the expansion evaporation gas supplied by injection, and the condensation evaporation gas cooled in the intercooler 360 may form the evaporation gas line BL. Accordingly supplied to the heat exchanger 210a.

In the heat exchanger 210a of the present embodiment, the condensed evaporated gas cooled by the intercooler 360 and LPG supplied from the LPG storage tank 100 to the LPG fuel engine E, more specifically, the LPG storage tank 100 The LPG supplied from the service tank 220 to the heat exchanger exchanges heat, and the boil-off gas is further cooled by cold heat of the LPG, and the cold heat is recovered and heated.

The reliquefaction system according to the present embodiment may further include a second expansion means 370 for reducing the boil-off gas cooled in the intercooler 360 to the internal pressure of the LPG storage tank 100.

That is, the condensed evaporation gas cooled in the intercooler 360 is reduced in the second expansion means 370 to the internal pressure of the LPG storage tank 100 and then recovered to the LPG storage tank 100.

While decompressing by the second expansion means 370, the boil-off gas may be lowered in temperature by depressurization.

The first expansion means 350 and / or the second expansion means 370 may be Joule-Thomson valves. That is, the temperature of the re-liquefied liquid evaporated gas may be lowered by the Joule-Thomson effect while being decompressed by the first expansion means 350 and / or the second expansion means 370.

 Although the first expansion means 350 and the second expansion means 370 of the present embodiment are described as an example of Joule-Thomson valve, but is not limited thereto, the first expansion means 350 and the second expansion means 370 ) May be a device having an expansion function such as an expander, a compander, or the like. The compander refers to a device in which the expander and the compressor are connected by one axis, and the compressor is driven by the expansion day of the expander.

In addition, the first expansion means 350 and the second expansion means 370 may be the same device having the above-described expansion function or may be different devices. For example, both the first expansion means 350 and the second expansion means 370 may be configured as Joule-Thomson valves, the first expansion means 350 is an expander, and the second expansion means 370 is a joule. It could be configured as a Thompson valve.

The first expansion means 350 and / or the second expansion means 370 may thermally expand the boil-off gas.

According to this embodiment, by further cooling by LPG to be supplied as fuel in the heat exchanger (210a), before further reducing the reliquefied evaporated gas to the internal pressure of the LPG storage tank 100 in the second expansion means 370, Compared to recovering the reliquefied boil-off gas without cooling by using the heat exchanger 210a, the LPG storage tank 100 can recover the re-liquefied boil-off gas having a lower temperature and a lower vapor fraction. Can be.

At the same time, by preheating the LPG to be supplied as the fuel of the LPG fuel engine E by heat exchange with the reliquefied evaporated gas, energy for heating the LPG fuel in accordance with the temperature conditions required by the LPG fuel engine E is reduced. Therefore, the heating duty of the after heater 250 can be reduced.

As described above, according to the present invention, by recovering the cold heat of LPG to be supplied as fuel while cooling the reliquefied evaporated gas, the energy for increasing the reliquefaction efficiency and heating the LPG fuel above the temperature required by the LPG fuel engine Can reduce the cost.

As yet another embodiment, the heat exchanger 210a may only operate when supplying LPG from the LPG storage tank 100 to the service tank 220, and may not operate otherwise.

Even if the heat exchanger 210a does not operate, all of the evaporated gas is liquefied by the reliquefaction process while passing through the reliquefaction system, and is recovered to the LPG storage tank 100 in a liquid state. More specifically, the entire amount of the evaporated gas may be liquefied while passing through the condenser 330.

The LPG fuel vessel according to the present embodiment is a heat source for reliquefying the boil-off gas generated in the LPG storage tank 100 and heating the temperature of the LPG fuel above the temperature required by the LPG fuel engine. In addition, the liquefied evaporated gas is recovered to the LPG storage tank (100).

The boil-off gas generated in the LPG storage tank 100 is compressed by the boil-off gas compressor 320, and the boil-off gas whose temperature has risen in the compression process is supplied to the intercooler 360 to be liquefied to re-liquefy the LPG storage tank 100. It can be cooled by using the cold heat of the reliquefaction evaporated gas recovered.

The boil-off gas compressor 320 compresses the boil-off gas to a set pressure in multiple stages. The set pressure may be, for example, a pressure at or above that the boil-off gas may become a liquid state at room temperature, or at least a critical pressure.

The boil-off gas introduced from the LPG storage tank 100 to the boil-off gas compressor 320 is supplied to the knockout drum 310 before being fed to the boil-off gas compressor 320, and the boil-off gas introduced to the boil-off gas compressor 320. After removing the liquid component such as droplets and mist contained in the gas may be supplied to the boil-off gas compressor (320).

In addition, the boil-off gas discharged from the inter-cooler 360 after being cooled in the intercooler 360 may be supplied after removing the liquid component contained in the boil-off gas before introducing into the next process. For example, a filter member may be disposed between the inlet of the boil-off gas and the outlet of the boil-off gas in the interior of the intercooler 360 so that the boil-off gas passes through the filter member to remove the liquid component.

The high pressure boil-off gas compressed by the boil-off gas compressor 320 may be condensed by heat exchange with a refrigerant, and in this process, the boil-off gas may be saturated. For example, the condenser 330 may condense the high pressure evaporated gas using cold heat of seawater. The boil-off gas discharged from the condenser 330 may be in a liquid state.

A part of the condensed evaporated gas is cooled by decompression or adiabatic expansion, and the decompressed or expanded expanded evaporated gas can be used as a refrigerant for cooling the remaining condensed evaporated gas which is not decompressed or expanded.

At this time, the expansion boil-off gas may be used as a refrigerant for cooling the boil-off gas whose temperature has risen in the above-described compression process.

That is, the intercooler 360 supplies the evaporated gas, the expanded evaporated gas, and the remaining condensed evaporated gas without decompressing or expanding the temperature in the compression process, and condensed with the evaporated gas with the elevated temperature in the compression process by cooling the expanded evaporated gas. The boil-off gas can be cooled.

The boil-off gas supplied as the refrigerant to the intercooler 360 may be injected into the intercooler 360. The condensed evaporated gas cooled by the cold heat of the expanded evaporated gas may be in a supercooled state.

The reliquefied boil-off gas in the liquid state cooled by the cold heat of the expanded boil-off gas is supplied to the LPG storage tank 100, wherein the pressure of the re-liquefied boil-off gas is supplied to the LPG storage tank by using the second expansion means 370. It can supply after reducing pressure to the internal pressure of (100).

When the second expansion means 370 is provided as a Joule-Thomson valve, in the process of reducing the pressure of the reliquefied boil-off gas, the temperature of the reliquefied boil-off gas may be lowered by the Joule-Thomson effect. Therefore, a larger amount of reliquefied boil-off gas can be recovered to the LPG storage tank 100.

In addition, before supplying the reliquefied evaporated gas in the liquid state cooled by the cold heat of the expanded evaporated gas to the second expansion means 370, it is supplied to the heat exchanger (210a), LPG fuel engine from the LPG storage tank 100 It can further cool using the cold heat of LPG supplied to (E).

Before depressurizing the reliquefied boil-off gas, by further cooling by using the cold heat of LPG to be supplied to the fuel of the LPG fuel engine E, the amount of flash gas generated in the depressurization process can be reduced. That is, the vapor fraction of the reliquefied boil-off gas recovered to the LPG storage tank 100 can be lowered and a larger amount of the boil-off gas can be recovered.

Before depressurizing the reliquefied boil-off gas, a process of further cooling by using the cold heat of LPG to be supplied as the fuel of the LPG fuel engine E, the pump for supplying LPG from the LPG storage tank 100 to the LPG fuel engine E It can be carried out intermittently when the operation, that is, when the demand for supplying the LPG from the LPG storage tank 100 to the LPG fuel engine (E) occurs.

The LPG fuel vessel of this embodiment can produce propulsion energy using LPG as fuel. That is, the LPG fuel engine E of the LPG fuel vessel uses LPG stored in the LPG storage tank 100 as fuel.

In order to supply LPG stored in the LPG storage tank 100 to the LPG fuel engine E, the LPG is discharged from the LPG storage tank 100 and preheated by heat exchange with the reliquefied boil-off gas. The preheated LPG is compressed to the pressure required in the LPG fuel engine E, for example about 40 bar to 70 bar or about 45 bar to 55 bar, preferably about 48 bar to 52 bar, and then LPG fuel The fuel required by the engine E is heated to, for example, about 20 ° C. to about 60 ° C., preferably about 25 ° C. to 55 ° C., to supply fuel to the LPG fuel engine E.

In this case, the LPG fuel supplied to the LPG fuel engine E may be in a liquid state.

Discharging the LPG to be supplied to the LPG fuel engine E from the LPG storage tank 100 can be performed using the feed pump 110 built in the LPG storage tank 100.

When the feed pump 110 is a fixed capacity pump, the LPG is temporarily stored in the service tank 220 before the LPG is compressed to the pressure required by the LPG fuel engine E, and the LPG is stored from the service tank 220. The flow rate of LPG supplied to the high pressure pump 230 to compress can be adjusted.

In addition, the step of heat-exchanging the reliquefied evaporated gas and LPG in the heat exchanger 210a to recover the cold heat of the LPG can be performed before the LPG is supplied to the service tank 220. That is, the service tank 220 may accommodate the LPG preheated in the heat exchanger 210a.

In this way, the LPG fuel can be heated above the minimum temperature required by the LPG fuel engine E by recovering the cold heat of the LPG to be supplied as the fuel of the LPG fuel engine E and cooling the reliquefied evaporated gas.

In addition, by preheating the LPG by recovering cold heat of the LPG to be supplied as fuel, the heating duty of the after-heater 250 for heating the temperature of the compressed LPG to the temperature required by the LPG fuel engine E is reduced, and the LPG is heated. Can save energy.

FIG. 3 is a schematic diagram illustrating an LPG fuel supply system and a reliquefaction system of an LPG fuel vessel according to a second embodiment of the present invention. The second embodiment of the present invention is a modification of the first embodiment, in which a heat exchanger 210b is provided between the receiver 340 and the intercooler 360 to preheat the LPG to be supplied as fuel and to cool the reliquefied boil-off gas. In the difference, and the rest of the components and the principle of operation is the same, so a detailed description will be omitted.

That is, in the heat exchanger 210b of the present embodiment, the LPG transferred from the LPG storage tank 100 to the service tank 220 and the reliquefied evaporated gas transferred from the receiver 340 to the intercooler 360 exchange heat. The LPG delivered to the tank 220 is heated and the reliquefied boil-off gas delivered to the intercooler 360 is cooled by cold heat of the LPG before being supplied to the intercooler 360.

According to the present embodiment, the boil-off gas to be reliquefied is compressed in the compressor 320, condensed in the condenser 330 and then cooled by cold heat of LPG in the heat exchanger 210b, and self-heat exchanged in the intercooler 360. After further cooled by the pressure reduction through the second expansion means 370 is recovered to the LPG storage tank (100).

In addition, the LPG is preheated by cooling the reliquefied boil-off gas supplied from the heat exchanger 210b to the intercooler 360 after being discharged from the LPG storage tank 100, and the preheated LPG is stored in the service tank 220. LPG stored in the service tank 220, the flow rate to supply to the engine (E) is compressed by the high-pressure pump 230, the after-heater 250 is adjusted to the temperature required by the engine (E) to the engine (E) Is supplied.

FIG. 4 is a schematic diagram illustrating an LPG fuel supply system and a reliquefaction system of an LPG fuel vessel according to a third embodiment of the present invention. The third embodiment of the present invention is a modification of the first embodiment, in which a heat exchanger 210c is provided between the receiver 340 and the intercooler 360 to preheat the LPG to be supplied as fuel and to cool the reliquefied evaporated gas. In the difference, and the rest of the components and the principle of operation is the same, so a detailed description will be omitted.

In the third embodiment of the present invention, the heat exchanger 210c is provided between the receiver 340 and the intercooler 360 as in the second embodiment, but there is a difference in the heat exchange target.

That is, in the heat exchanger 210c according to the present embodiment, the LPG supplied from the service tank 220 to the engine E and the reliquefied boil-off gas transferred from the receiver 340 to the intercooler 360 exchange heat and heat the engine ( The LPG supplied to E) is heated, and the reliquefied boil-off gas sent to the intercooler 360 is cooled by cold heat of the LPG before being supplied to the intercooler 360.

The LPG, which exchanges heat with the reliquefaction evaporated gas in the heat exchanger 210c, is discharged from the service tank 220, compressed by the high pressure pump 230, and after the foreign matter is removed through the filter 240, the after heater 250. LPG may be introduced into.

According to the present embodiment, the boil-off gas to be reliquefied is compressed in the compressor 320, condensed in the condenser 330 and then cooled by cold heat of LPG in the heat exchanger 210c, and self-heat exchanged in the intercooler 360. After further cooled by the pressure reduction through the second expansion means 370 is recovered to the LPG storage tank (100).

In addition, LPG is transferred from the LPG storage tank 100 to the service tank 220, the LPG of the amount to be supplied from the service tank 220 to the engine E is compressed by the high pressure pump 230, the heat exchanger After being preheated while cooling the reliquefied evaporated gas at 210c, the after heater 250 is adjusted to a temperature required by the engine E and supplied to the engine E.

As described above, the embodiments of the present invention have been described, and the fact that the present invention can be embodied in other specific forms without departing from the spirit or scope of the present invention can be embodied by those skilled in the art. It is self-evident to. The foregoing embodiments are, therefore, to be regarded in an illustrative rather than a restrictive sense, and thus, the invention is not limited to the above description, and may vary within the scope of the appended claims and their equivalents.

100: LPG Storage Tank
110: feed pump
210a, 210b, 210c: heat exchanger
220: service tank
230: high pressure pump
240: filter
250: After Heater
E: LPG Fuel Engine
310: knockout drum
320: boil off gas compressor
330: condenser
340: Receiver
350: first expansion means
360: intercooler
370 second expansion means
FL: Fuel Supply Line
BL: Boil off gas line
BL1: Boil off gas branch line
SL: Recovery Line

Claims (16)

LPG storage tank for storing LPG (Liquefied Petroleum Gas);
LPG fuel engines using LPG as fuel;
A reliquefaction system for reliquefying the boil-off gas generated in the LPG storage tank to recover the LPG storage tank;
A heat exchanger for recovering cold heat of the LPG by heat-exchanging the LPG to be supplied to the LPG fuel engine and the boil-off gas liquefied in the reliquefaction system; And
And an after-heater for heating the LPG from which the heat of cold is recovered by the heat exchanger to a temperature required by the LPG fuel engine. The method according to claim 1,
And a high pressure pump for compressing the LPG recovered from the heat of the cold in the heat exchanger to the pressure required by the LPG fuel engine. The method according to claim 2,
The pressure required by the LPG fuel engine is an LPG fuel vessel, 45 bar to 55 bar. The method according to claim 1,
The minimum temperature required by the LPG fuel engine is 20 ℃ to 25 ℃,
The after-heater, LPG fuel vessel, which can heat the LPG to 50 ℃ to 60 ℃. The method according to claim 2,
A feed pump provided in the LPG storage tank and configured to pressurize the LPG stored in the LPG storage tank and discharge the LPG to the outside of the LPG storage tank; And
And a service tank storing LPG preheated in the heat exchanger after discharged by the feed pump, and adjusting a flow rate of LPG supplied to the high pressure pump. The method according to claim 5,
And a recovery line connecting the LPG fuel engine and the service tank and flowing a gaseous gas from the LPG fuel engine to the service tank.
The gas transferred to the service tank through the recovery line is condensed by cold heat of the LPG stored in the service tank, LPG fuel vessel. The method according to claim 5,
The boil-off gas generated in the service tank is sent to the reliquefaction system,
The reliquefaction system LPG fuel ship to recover the LPG storage tank by reliquefying the boil-off gas generated in the LPG storage tank and the boil-off gas generated in the service tank. The method according to claim 1 or 7,
The reliquefaction system,
An evaporative gas compressor for compressing the evaporated gas; And
And an intercooler for cooling the boil-off gas whose temperature has risen by the compression. The method according to claim 8,
The reliquefaction system,
First expansion means for cooling the evaporated gas re-liquefied and recovered in the LPG storage tank by reduced pressure; And
And a boil-off gas branch line for flowing the boil-off gas cooled by the first expansion means to the intercooler.
The boil-off gas cooled by the first expansion means is used as a refrigerant in the intercooler. The method according to claim 9,
The reliquefaction system,
A condenser for condensing the compressed boil-off gas compressed by the boil-off gas compressor; And
And an evaporation gas line connecting the condenser and the intercooler and flowing the evaporated gas in the liquid state condensed in the condenser to the intercooler.
The boil-off gas branch line is branched from the boil-off gas line,
In the intercooler,
The evaporation gas cooled by the said 1st expansion means cools, and the evaporation gas which temperature rose by the said compression, and the remaining evaporation gas which are not expanded are cooled, LPG fuel ship. The method according to claim 10,
The reliquefaction system,
And second expansion means for depressurizing the reliquefied boil-off gas cooled in the intercooler or the reliquefied boil-off gas cooled in the intercooler and the heat exchanger to the internal pressure of the LPG storage tank. LPG stored in the LPG storage tank is supplied as the fuel of the engine, and the boil-off gas generated by LPG natural vaporization is re-liquefied and recovered into the LPG storage tank,
Heat-exchanging the LPG to be supplied as fuel of the engine and the reliquefied boil-off gas recovered to the LPG storage tank;
Compressing the LPG heated by the heat exchange to a pressure required by the engine; And
And further heating the compressed LPG to a temperature required by the engine. The method according to claim 12,
Operating a feed pump to discharge LPG to be heat exchanged with the reliquefied boil-off gas from the LPG storage tank; And
Supplying the heated LPG to the service tank by heat exchange with the reliquefied boil-off gas;
LPG is discharged from the service tank and compressed to the pressure required by the engine, thereby adjusting the flow rate of the LPG to be supplied to the engine, LPG fuel vessel fuel supply method. The method according to claim 12,
Compressing the boil-off gas in multiple stages;
Condensing the compressed boil-off gas;
Cooling the condensation boil off gas; And
And depressurizing the cooled reliquefied boil-off gas to the internal pressure of the LPG storage tank. The method according to claim 14,
Compressing the boil-off gas in multiple stages,
And cooling the boil-off gas whose temperature has risen by compression.
The cooling of the condensation boil-off gas may include cooling at least a portion of the condensation boil-off gas by expansion.
And supplying the expanded evaporated gas cooled by the expansion to be used as a refrigerant for cooling the evaporated gas whose temperature has risen by the compression and the remaining uncondensed condensed evaporated gas. The method according to claim 15,
The cooled reliquefaction evaporated gas is heat-exchanged with the LPG to be supplied as the fuel of the engine, further cooled, and decompressed to recover the LPG storage tank, LPG fuel vessel fuel supply method.

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