KR20170055397A - A LNG Carrier - Google Patents

Abstract

According to the present invention, an LNG carrier comprises: a liquefied gas storage tank storing liquefied gas; a boil-off gas compressor supplying boil-off gas generated in the liquefied gas storage tank as a fuel of an engine; a reliquefying device liquefying the remaining boil-off gas which is not supplied to the engine. The present invention increase output of the engine to reduce the remaining boil-off gas which is not supplied to the engine in order to reduce the remaining boil-off gas introduced to the reliquefying device.

Description

LNG Carrier {A LNG Carrier}

The present invention relates to an LNG carrier.

A ship is a means of transporting large quantities of minerals, crude oil, natural gas, or several thousand containers. It is made of steel and buoyant to float on the water surface. The thrust generated by rotation of the propeller ≪ / RTI >

Such a vessel generates thrust by driving the engine. In this case, the engine uses gasoline or diesel to move the piston so that the crankshaft is rotated by the reciprocating motion of the piston, so that the shaft connected to the crankshaft is rotated to drive the propeller It was common.

However, recently, as a fuel for ships, liquefied natural gas such as Liquefied Natural Gas (Liquefied Natural Gas) and Liquefied Petroleum Gas (Liquefied Petroleum Gas) have been used instead of gasoline or diesel to propel various vessels such as LNG carriers and container carriers .

When the liquefied gas is stored in the liquid state, heat penetration into the liquefied gas storage tank causes some of the liquefied gas to vaporize and generate a boiled off gas. This evaporated gas is called Natural Boiled off Gas (NBOG In the past, the evaporation gas was simply discharged to the outside in order to lower the pressure of the tank and to eliminate the risk of breakage of the tank. To solve the problem.

However, this causes environmental pollution and waste of resources. Therefore, in order to solve such a problem, many researches and developments have been made on techniques for reducing the boil-off rate (BOR), which is the rate at which liquefied gas is naturally produced in the liquefied gas storage tank It is in progress.

SUMMARY OF THE INVENTION The present invention has been made to improve the prior art, and it is an object of the present invention to provide an LNG carrier which processes a liquefied gas by applying a liquefied gas storage tank having a low vaporization rate (BOR).

An LNG carrier according to the present invention comprises: a liquefied gas storage tank for storing a liquefied gas; An evaporative gas compressor for supplying evaporative gas generated in the liquefied gas storage tank to the fuel of the engine; And a liquefaction device for liquefying excess evaporation gas not supplied to the engine, wherein by increasing the output of the engine and reducing the excess evaporation gas not supplied to the engine, Thereby reducing the excess evaporative gas.

Specifically, the liquefied gas storage tank stores the liquefied gas and may have a low rate of combustion of 0.7% to 0.9%.

Specifically, the engine may be a low pressure gas injection engine (XDF).

Specifically, an evaporative gas supply line connects the liquefied gas storage tank and the engine, and supplies evaporative gas generated in the liquefied gas storage tank to the engine. And a liquefied gas supply line that connects the liquefied gas storage tank and the engine and supplies the liquefied gas stored in the liquefied gas storage tank to the propulsion device.

A boosting pump provided on the liquefied gas supply line for pressurizing the liquefied gas stored in the liquefied gas storage tank; And a forced vaporizer for vaporizing the liquefied gas supplied from the boosting pump.

Specifically, a shaft generator provided on a rotating shaft of the engine; And a power generation engine that generates power using the evaporation gas or oil, wherein the shaft generator develops as an output increase of the engine, and the power generation engine can reduce a load by an amount of power generation of the shaft generator.

The LNG carrier according to the present invention has an effect of facilitating the treatment of the liquefied gas or the evaporated gas by optimally applying the liquefied gas storage tank with low vaporization rate to the LNG carrier.

1 is a conceptual diagram of an LNG carrier according to an embodiment of the present invention.
2 is a conceptual diagram of an LNG carrier according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The objects, particular advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the drawings, the same reference numerals are used throughout the drawings to refer to the same or similar components. However, the same reference numerals are used in the different drawings to designate the same or similar components. shall. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

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

FIG. 1 is a conceptual view of an LNG carrier according to an embodiment of the present invention, and FIG. 2 is a conceptual view of an LNG carrier according to another embodiment of the present invention.

1 and 2, a gas processing system 1 according to an embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a high-pressure pump 21, a forced vaporizer 30, Liquid separator 61, an expansion valve 62, a propulsion engine 70, a gas combustion device 71, a power generation engine 72, and a power generation engine 72. The heat exchanger 40, the evaporation gas compressor 50, the refueling device 60, , And a shaft generator (80).

Hereinafter, the liquefied gas may be used to encompass all gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc. In the case where the gas is not in a liquid state by heating or pressurization, . This also applies to the evaporative gas. In addition, LNG can be used to mean not only NG (Natural Gas) in liquid state but also NG in supercritical state for convenience, and evaporation gas can be used to include not only gaseous evaporation gas but also liquefied evaporation gas have.

Hereinafter, a gas processing system 1 according to an embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

The liquefied gas storage tank 10 stores liquefied gas to be supplied to the propulsion engine 70, the gas combustion device 71, the power generation engine 72, and the like. The liquefied gas storage tank 10 must store the liquefied gas in a liquid state, at which time the liquefied gas storage tank 10 may have the form of a pressure tank.

The liquefied gas storage tank 10 according to the present invention allows the liquefied gas to perform a sufficient heat insulation from an external heat source and to provide a liquefied gas storage tank having a boiling off rate (BOR) (Low BOR liquefied gas storage tank) of 0.7% to 0.8% (preferably 0.75%).

Preferably, the liquefied gas storage tank 10 may be a GTT Mark V or a Low BOR Mark 5 jointly developed by the present applicant with GTT Company (GazTransport & Technigaz).

In the description of the present invention, the term "BOR" refers to a diurnalization rate. The term BOR means 0.7% to 0.8% means that BOR is 0.070% / day to 0.080% / day. Can be similarly interpreted.

The boosting pump 20 supplies the liquefied gas stored in the liquefied gas storage tank 10 to the high-pressure pump 21, which is installed inside or outside the liquefied gas storage tank 10, So that cavitation of the high-pressure pump 21 can be prevented.

The boosting pump 20 can extract the liquefied gas from the liquefied gas storage tank 10 and pressurize it to several to several tens of bar and the liquefied gas through the boosting pump 20 can be pressurized from 1 bar to 25 bar.

The liquefied gas stored in the liquefied gas storage tank 10 is in a liquid state. At this time, the boosting pump 20 may pressurize the liquefied gas discharged from the liquefied gas storage tank 10 to slightly increase the pressure and the temperature, and the liquefied gas pressurized by the boosting pump 20 may still be in a liquid state .

The high-pressure pump 21 pressurizes the liquefied gas discharged from the liquefied gas storage tank 10 at a high pressure to be supplied to the propulsion engine 70 and the like. The liquefied gas is discharged from the liquefied gas storage tank 10 at a pressure of about 10 bar and is then primarily pressurized by the boosting pump 20. The high pressure pump 21 is operated by the boosting pump 20 in a liquid state And supplies the pressurized gas to the heat exchanger (40).

At this time, the high-pressure pump 21 can pressurize the liquefied gas to a pressure required by the propulsion engine 70, for example, 200 to 400 bar.

The high pressure pump 21 pressurizes the liquid liquefied gas discharged from the boosting pump 20 at a high pressure so that the liquefied gas becomes a supercritical state having a temperature higher than the critical point and a high pressure, . At this time, the temperature of the liquefied gas in the supercritical state may be minus 20 degrees or less, which is relatively higher than the critical temperature.

Or the high-pressure pump 21 can pressurize the liquefied gas in the liquid state to a super-cooled liquid state by pressurizing it with a high pressure. Here, the supercooled liquid state means a state where the pressure of the liquefied gas is higher than the critical pressure and the temperature is lower than the critical temperature.

Specifically, the high-pressure pump 21 pressurizes the liquid-state liquefied gas discharged from the boosting pump 20 at a high pressure of 200 to 400 bar, and the liquefied gas is cooled to a temperature lower than the critical temperature, Phase state to a liquid state. Here, the temperature of the liquefied gas in the subcooled liquid state may be minus 140 degrees to minus 60 degrees lower than the critical temperature.

The forced vaporizer (30) can supply the liquefied gas stored in the liquefied gas storage tank (10) from the boosting pump (20) and can be forcedly vaporized. The forced vaporizer 30 is operated when the flow rate of the evaporation gas is insufficient to increase the flow rate of the evaporation gas supplied to the propulsion engine 70 or the power generation engine 72. [

The forced vaporizer 30 can partially vaporize the liquefied gas by adjusting the heating temperature to increase the methane price of the liquefied gas supplied to the propulsion engine 70 or the power generation engine 72. In this case, To -120 < 0 > C. The partially vaporized liquefied gas is supplied only to the propulsion engine 70 or the power generation engine 72 through the temporary storage tank (not shown) provided at the rear end of the forced vaporizer 30 and the liquid phase is supplied to the liquefied gas storage tank 10).

The heat exchanger 40 is provided between the propulsion engine 70 and the high-pressure pump 21 to vaporize the liquefied gas supplied from the high-pressure pump 21. The heat exchanger 40 heats the liquefied gas in the subcooled liquid state or the supercritical state while maintaining the pressure of 200 bar to 400 bar discharged from the high-pressure pump 21, converts the liquefied gas into supercritical liquefied gas at 30 to 60 degrees To the propulsion engine (70).

At this time, the heat exchanger 40 may vaporize the liquefied gas by using an indirect heat exchange method using glycol water, but it is not limited thereto, and steam, seawater, fresh water, And the like can be used.

The evaporative gas compressor (50) can pressurize the evaporated gas generated in the liquefied gas storage tank (10). The evaporative gas compressor 50 can supply the evaporative gas generated in the liquefied gas storage tank 10 and discharged at a pressure of about 10 bar to the propulsion engine 70 at a pressure of 200 bar to 400 bar. At this time, the evaporative gas compressor 50 may be a reciprocating evaporative gas compressor 50a, and the propulsion engine 70 may be a MEGI engine 70a.

A plurality of evaporation gas compressors (50) may be provided to pressurize the evaporation gas at multiple stages. For example, the evaporative gas compressor (50) is provided with an evaporation gas first stage compressor, an evaporation gas second stage compressor, an evaporation gas third stage compressor, an evaporation gas fourth stage compressor, an evaporation gas It is composed of five 5-stage compressors, so that the evaporation gas can be pressurized in five stages.

Specifically, the evaporative gas compressor 50 is introduced at about 1.05 bar in the liquefied gas storage tank 10 and is pressurized to about 5 bar in the evaporator gas first stage compressor and about 15 bar in the evaporative gas second stage compressor , About 90 bar in the evaporator third stage compressor, about 150 bar in the fourth evaporator gas compressor, and about 300 bar in the fifth evaporator gas compressor.

However, the pressure of the evaporative gas discharged from each stage described above is not limited to one example, and can be changed through a separate operation.

The evaporated gas pressurized by the evaporation gas second stage compressor is supplied to the gas combustion apparatus 71 or the power generation engine 72 through the evaporation gas first and second branch lines L3 and L4, Stage compressing unit through the first line L1, and the evaporation gas pressurized in the fifth evaporation gas compressor is supplied to the propulsion engine 70 by the evaporation gas supply line L1 .

Further, the evaporative gas compressor (50) can pressurize the evaporative gas generated in the liquefied gas storage tank (10). The evaporative gas compressor 50 can pressurize the evaporative gas generated in the liquefied gas storage tank 10 and discharged at a pressure of about 1 bar or so to 20 to 40 bar (preferably 25 bar) to the propulsion engine 70. At this time, the evaporative gas compressor 50 may be a centrifugal evaporative gas compressor 50b, and the propulsion engine 70 may be an XDF engine 70b.

Here, the evaporation gas supplied to the evaporation gas supply line (L1) and the liquefied gas supplied to the liquefied gas supply line (L2) may be mixed and supplied to the propulsion engine (70). To this end, a mixer (not shown) may be provided upstream of the propulsion engine 70.

Between each stage of the evaporative gas compressors, an evaporative gas cooler (not shown) may be provided. When the evaporation gas is pressurized by the evaporation gas compressor 50, the temperature can also be raised according to the pressure increase. Therefore, in this embodiment, the evaporation gas cooler can be used to lower the temperature of the evaporation gas again.

The evaporative gas cooler may be installed in the same number as the evaporative gas compressor 50, and each evaporative gas cooler may be provided downstream of each evaporative gas compressor.

In addition to adjusting the fuel pressure required by the propulsion engine 70, the evaporation gas compressor 50 pressurizes the evaporation gas in order to increase the liquefaction efficiency of the evaporation gas. Evaporation gas increases the boiling point when the pressure rises, which means that it can be liquefied even at relatively high temperatures. Therefore, this embodiment can increase the pressure of the evaporation gas to the evaporation gas compressor 50, so that the evaporation gas can be easily liquefied. At this time, the evaporated gas discharged from the evaporating gas compressor (50) located at the end based on the flow of the evaporating gas may have a pressure of 200 to 400 bar. This high-pressure evaporation gas can be supplied to at least a part of the refueling device 60 through the evaporation gas refill line L5.

The re-liquefier 60 is provided between the liquefied gas storage tank 10 and the evaporative gas compressor 50 to re-liquefy the evaporated gas compressed in the evaporative gas compressor 50.

The re-liquefier 60 of the present invention includes an evaporative gas heat exchanger 60a (at least partially re-liquefying the evaporative gas supplied from the liquefied gas storage tank 10) and at least partially re-liquefying the evaporative gas compressed at the high pressure in the evaporative gas compressor 50 ). At this time, the evaporation gas supplied to the evaporation gas heat exchanger 60a may be evaporated gas compressed to 200 to 400 bar by the reciprocating evaporation gas compressor 50a.

The evaporation gas heat exchanger 60a supplies evaporation gas heat exchanged and at least partially re-liquefied to an expansion valve 62 (for example, a decompressor or an expander) provided downstream, Re-liquefaction can be implemented.

The redistribution device (60) of the present invention may be a refrigerant heat exchanger (60b) for re-liquefying the evaporated gas using another refrigerant. At this time, the evaporation gas supplied to the refrigerant heat exchanger 60b may be evaporated gas compressed to 20 to 40 bar by the centrifugal evaporation gas compressor 50b.

Since the refrigerant heat exchanger 60b re-liquefies the evaporation gas using a separate refrigerant, it is not necessary to compress the evaporation gas to a high pressure, and therefore, the evaporation gas compressed at a low pressure by the centrifugal type evaporation gas compressor 50b is sufficiently Can be re-liquefied.

The gas-liquid separator 61 receives vaporized gas re-liquefied in the re-liquefier 60 and separates the gas phase and the liquid phase. The evaporated gas separated into the liquid and the gas in the gas-liquid separator 61 is returned to the liquefied gas storage tank 10 through the liquefied gas return line L6 and the gas is supplied again to the liquefier 60, Can be supplied to the combustion device 71 and consumed.

The expansion valve 62 pressurizes or expands the compressed evaporated gas heat-exchanged in the evaporative gas heat exchanger 60a to liquefy it. For example, the expansion valve 62 can reduce the pressure of the evaporation gas to 1 bar to 10 bar, and the evaporation gas can be liquefied and reduced to 1 bar when transferred to the liquefied gas storage tank 10, Effect can be achieved.

In this case, the cooling effect of the evaporated gas may be increased as the pressure range to be depressurized is increased. For example, the expansion valve 62 may reduce the evaporated gas compressed to 200 to 400 bar to 1 bar by the reciprocating evaporative gas compressor 50a have.

The expansion valve 62 may be a line Thompson valve. Alternatively, the expansion valve 62 may comprise an inflator (not shown). In the case of the Row Thompson valve, depressurization can effectively cool the evaporated gas so that at least some of the evaporated gas is liquefied. At this time, the inflator may also be made of an expander (not shown).

On the other hand, the inflator can be driven without using any additional power, and in particular, the efficiency of the gas processing system 1 can be improved by utilizing the generated power as electric power for driving the evaporative gas compressor 50. The power transmission may be accomplished by, for example, a gear connection or an electric conversion and the like.

The propulsion engine 70 uses evaporative gas or liquefied gas supplied from the liquefied gas storage tank 10 as fuel. At this time, the propulsion engine 70 may be a high pressure gas injection engine (e.g., MEGI 70a) or a low pressure gas injection engine (e.g., XDF 70b). In the case of the MEGI engine 70a, an evaporated gas pressurized at a high pressure of about 200 to 400 bar is used as fuel, and as the XDF engine 70b, a pressurized gas at a low pressure of about 1 to 25 bar is used as the fuel.

As the piston (not shown) inside the cylinder (not shown) reciprocates due to the combustion of the liquefied gas, the engine rotates the crankshaft (not shown) connected to the piston and rotates the propeller shaft 91 can be rotated. Therefore, as the propeller 90 connected to the propeller shaft 91 rotates when the propulsion engine 70 is driven, the hull 2 can move forward or backward.

Propulsion engine 70 is a two-stroke DF engine typically driven by a diesel cycle and may be a low speed engine. In this diesel cycle, air is compressed by the piston, the compressed high-temperature air is ignited by a pilot fuel, and the remaining high-pressure gas is injected and exploded.

In this case, the ignition fuel uses HFO (Heavy Fuel Oil) or MDO (Marine Diesel Oil), the ratio of the ignition fuel to the high-pressure gas is about 5:95, and the injection amount of the ignition fuel is adjusted to 5 to 100% It is possible. Therefore, the ignition fuel is also usable as the driving fuel for the engine.

That is, when the injection amount of the ignition fuel is about 5%, evaporative gas (or heated liquefied gas; about 95%) is mainly used as the engine driving fuel, and when the injection amount of the ignition fuel is 100% Fuel (oil) is all used.

At this time, when the injection amount of the ignition fuel is about 50% (and about 50% of the evaporation gas), the ignition fuel and the evaporation gas are mixed and not ignited into the engine, but the ignition fuel is ignited first to generate a calorific value, Gas is introduced and exploded to produce a calorific value, thereby producing a calorific value required for driving the engine.

A gas combustion unit (a gas combustion unit) 71 consumes the evaporation gas generated in the liquefied gas storage tank 10 by burning it. Specifically, the gas combustion apparatus 71 pressurizes and supplies the evaporated gas generated in the liquefied gas storage tank 10 through the evaporative gas compressor 50 or consumes the flash gas generated in the gas-liquid separator 61 And it is possible to treat and receive the pressurized evaporated gas at a pressure of about 1 to 50 bar.

The gas combustion device 71 can be changed in pressure depending on its type, and the combustion pressure can be freely adjusted by the user.

The power generation engine 72 uses evaporative gas or liquefied gas supplied from the liquefied gas storage tank 10 as fuel. At this time, the power generation engine 72 may be DFDE or DFDG as a heterogeneous fuel propulsion engine.

The power generation engine 72 uses a low-pressure evaporation gas of about 7 to 10 bar and can use oil as fuel as well as liquefied gas. Here, the power generation engine 72 is driven by receiving the evaporative gas branched and discharged from the middle stage of the evaporative gas compressor 50, or supplied with the evaporative gas compressed at the low pressure by the evaporative gas compressor 50 .

This power generation engine 72 is typically a four-stroke engine and may be a medium speed engine.

The shaft generator 80 is installed on the propeller shaft 91 driven by the propulsion engine 70 and can be engaged with and engaged with the propulsion engine 70 to generate power from the propulsion engine 70 And supply electric power to the electric equipment (not shown).

The shaft generator 80 provides resistance to the drive of the propulsion engine 70 which causes the hull 2 to increase the output to the propulsion engine 70 without further increasing the propulsion speed, (Preferably a surplus of evaporated gas) can be consumed.

Through the process in which the evaporation gas is consumed by the shaft generator 80 and the electric power is produced thereby, it is possible to solve the environmental problem due to the incineration of the evaporative gas and to efficiently utilize the surplus resources, have.

The control of the gas processing system 1 according to the embodiment of the present invention will be described in detail on the basis of each of the above-described configurations.

Recently, it has been used as propellant for a variety of vessels such as LNG carriers and container carriers using liquefied gas such as liquefied natural gas (Liquefied Natural Gas) and liquefied petroleum gas .

When the liquefied gas is stored in the liquid state, heat penetration into the liquefied gas storage tank causes some of the liquefied gas to vaporize and generate a boiled off gas. This evaporated gas is called Natural Boiled off Gas (NBOG In the past, the evaporation gas was simply discharged to the outside in order to lower the pressure of the tank and to eliminate the risk of breakage of the tank. To solve the problem.

However, this causes problems of environmental pollution and waste of resources. To solve this problem, NBOG has been used as a driving fuel for ship engine.

The rate at which liquefied gas naturally generates vapor in a liquefied gas storage tank is called the Boil-Off Rate (BOR). The initial liquefied gas storage tank has a poor BOR due to poor heat insulation performance, approaching 0.15% And the amount of natural evaporation gas generated thereby was considerably large. Steam engine has been selected as a marine engine in order to consume such natural evaporation gas as ship propulsion fuel.

As the technology of ship engine gradually developed, a high efficiency heterogeneous fuel propulsion engine (DFDE) was developed, and a heterogeneous fuel propulsion engine was placed in place of a low efficiency steam engine.

Fuel-fueled propulsion engines produced the same propulsion power as steam engines even with a small amount of natural evaporation gas, and the natural evaporation gas generated from the conventional liquefied gas storage tank (BOR 0.15%) was too high compared to the engine capacity with such high efficiency fuel efficiency The surplus evaporation gas can not be treated as the fuel of the propulsion engine, and the surplus evaporation gas is processed through the equipment such as the re-liquefaction device or the gas combustion device, so that additional equipment is added, which is preferable in terms of manufacturing cost of the ship It has resulted in failure.

In this study, the thermal insulation performance of liquefied gas storage tanks was investigated to reduce the vaporization rate (BOR) of liquefied gas storage tanks to 0.9% ~ 0.11%, thereby reducing the generation of surplus vapor.

 The technology development of the marine engine did not stop at the hybrid fuel propulsion engine. Continuous research and development has led to the development of high-pressure gas injection engines (ME-GI) and XDFs, which have developed engines with better performance than propellant engines.

These high-pressure gas injection engines and XDFs have high fuel efficiency and fuel efficiency as well as the propulsion speed of ships. This resulted in remarkable results in terms of performance of the ship, but again caused the problem of the surplus evaporative gas treatment of the liquefied gas storage tank.

The GTT company (GazTransport & Technigaz) and the present applicant coined the GTT Mark V, which greatly reduced the vaporization rate (BOR) of the liquefied gas storage tank from about 0.7% to 0.8%, laying the groundwork for solving the above problems.

Hereinafter, a liquefied gas storage tank having such a low rate is applied to a liquefied gas processing system, and various control techniques are described.

<Basic drive>

In the embodiment of the present invention, the gas processing system 1 is constructed on the basis of the low rate liquefied gas storage tank 10. Since the liquefied gas storage tank is constructed with the low-rate liquefied gas storage tank 10, the amount of the natural evaporation gas (NBOG) is small compared with the conventional case. The design speed that can be implemented by the ship through the natural evaporation gas is liquefied When the propulsion engine 70 consumes all the evaporation gas generated from the gas, the propulsion speed of the ship may be about 16 Knots. However, even in the gas processing system 1 in which the liquefied gas storage tank 10 having the lower rate is built, NBOG is generated even though the ship is proceeding at the design speed of the ship, and surplus evaporative gas may be generated. Accordingly, in the present invention, it is consumed through the maximum speed of the ship (Design Speed: usually 19.5 Knots). Such a gas treatment system 1 of the present invention can produce a maximum speed of the ship and a margin of about 3.5 knots (ease of management of surplus evaporated gas through the linear velocity). That is, the larger the margin, the greater the ability to treat the surplus evaporated gas without a separate evaporative gas treatment system.

The evaporation gas generated in the liquefied gas storage tank 10 is supplied to the evaporation gas compressor 50 through the evaporator 50. [ So that the ship is driven to realize the design speed by supplying it to the propulsion engine 70 or the power generation engine 72 and consuming it.

When the vessel is required to express an additional speed beyond the design speed, the liquefied gas stored in the low-rate liquefied gas storage tank 10 is pressurized through the booster pump 20 to 1 to 25 bar, and then the forced vaporizer 30 ) To the propulsion engine 70 (when the propulsion engine 70 is an XDF engine) or by pressurizing the liquefied gas that has been pressurized through the boosting pump 20 with the high-pressure pump 21, 400 bar and then heated to heat exchanger 40 and supplied to propulsion engine 70 (when propulsion engine 70 is a MEGI engine).

< Axial pressure control >

In the above basic operation, in the case where surplus evaporation gas exists in the evaporation gas generated in the low-rate liquefied gas storage tank 10, in the present invention, it is possible to control the condensation rate as it is in the liquefied gas storage tank 10 have. At this time, the lower rate liquefied gas storage tank 10 is capable of accumulating pressure until the internal pressure of the tank becomes about 0.25 bar.

< Line speed control >

Alternatively, in the above-mentioned basic driving, when there is a surplus evaporation gas in the evaporation gas generated in the liquefied gas storage tank 10 at the rate of low saturation, in the present invention, the drive for increasing the linear velocity up to the maximum speed (design speed) Can be controlled.

In the present invention, when excess evaporation gas is present in the evaporation gas generated in the liquefied gas storage tank 10 at a low rate, it is possible to process the surplus evaporation gas individually in the accumulation control or the linear speed control as described above, It is of course possible to use a combination of the two controls in the case where the surplus evaporated gas increases to an unpredictable extent due to the additional heat input.

As described above, according to the embodiment of the present invention, since the extra liquefaction device or the gas combustion device is not required in order to process the excess evaporative gas through the axial pressure control or the linear speed control, the system construction cost is reduced and the space utilization of the ship is dramatically . &Lt; / RTI &gt;

The upper limit of the wire speed can be additionally set and controlled in the above-described wire speed control. In this case, a gas combustion apparatus 71 and a shaft generator 80 are additionally constructed in the gas processing system 1.

Specifically, in the present invention, the upper limit of the line speed is first set in the navigating system of the ship. After that, the ship realizes the gas processing system (1) through the basic operation, and then, when the surplus evaporation gas is generated, the surplus evaporation gas can be controlled by varying the linear velocity below the design speed or below the upper limit of the line speed.

However, in the case where surplus evaporation gas having an upper limit of the line speed is generated, the surplus evaporation gas is consumed through the gas combustion device 71 without further increasing the speed of the ship, or the shaft generator 80 is operated to consume the surplus evaporation gas Can be controlled.

Accordingly, in the present invention, it is possible to control the surplus evaporating gas to be variable in the linear velocity, and at the same time to solve the problems such as collision and path deviation which may occur due to the excessively high linear velocity.

&Lt; Control of power generation engine 72 >

When the shaft generator 80 is controlled in the above-described navigation control, the power generation engine 72 can be additionally controlled.

The power generation engine 72 consumes the evaporation gas or the stored liquefied gas generated in the liquefied gas storage tank 10 at a low rate. It is not a problem that the liquefied gas is supplied when the supply of the additional fuel to the power generation engine 72 is required. However, even when the shaft generator 80 is operated as in the above navigation control, The liquefied gas is unnecessarily introduced.

Therefore, in the present invention, when the shaft generator 80 is operated, power is supplied through the shaft generator 80, so that when the shaft generator 80 operates, at least some of the four power generation engines 72 The power generation engine 72 is driven by only two power generators).

As described above, according to the present invention, efficient use of the surplus evaporating gas can be optimized through the control of the power generation engine 72, whereby only two ships can be mounted on the ship when the first power generation engine 72 is mounted, Cost reduction effect can be obtained.

< Remelting control >

The re-liquefaction control can additionally be set in the above-described axial pressure control or linear velocity control. In this case, it is possible to omit the gas combustion device 71 in the gas treatment system 1 and to additionally construct the re-liquefier 60.

When the re-liquefaction control is added to the line speed control, in the present invention, at the time of the basic operation of the gas processing system 1, at least a portion of the evaporated gas pressurized by the evaporative gas compressor 50 is supplied to the re-liquefier 60 Setting. After that, the ship realizes the gas processing system (1) through the basic operation, and when the surplus evaporation gas is generated, the surplus evaporation gas can be controlled by varying the linear velocity below the design speed or below the maximum speed.

Specifically, assuming that the evaporation gas flow rate supplied from the low-rate liquefied gas storage tank 10 to the refueling device 60 is A1 and the evaporated gas pressurized by the evaporation gas compressor 50 is supplied to the refueling device 60 When the evaporation gas flow rate is B1, the basic setting can be set to A1: B1 as 3: 1 as an example. In this case, the flow rate of the evaporation gas supplied to the propulsion engine 70 by the evaporation gas pressurized by the evaporation gas compressor 50 with respect to the evaporation gas flow rate supplied from the low rate liquefied gas storage tank 10 to the refueling device 60 is 3: 2.

When the surplus evaporation gas is generated in the above basic setting, the evaporation gas flow rate supplied from the evaporation gas compressor (50) to the refueling device (60) in order to vary the linear speed above the design speed is relatively large Can be reduced. (In this case, preferably, the absolute amount of the zeol gas flowing into the remelting device 60 does not change).

That is, when A1: B1 is changed to 4: 1, the evaporation gas pressurized in the evaporation gas compressor 50 with respect to the evaporation gas flow rate supplied from the low rate liquefied gas storage tank 10 to the refueling device 60 is supplied to the propulsion engine The flow rate of the evaporation gas supplied to the refueling apparatus 70 becomes 4: 3, thereby increasing the amount of the evaporation gas supplied to the propulsion engine 70 and reducing the flow rate supplied to the refueling apparatus 60.

Accordingly, the re-liquefier 60 has an effect of drastically improving the re-liquefaction rate because A1, which is the flow rate of the remanufacturing main body which serves as a refrigerant, is larger than B1, which is the flow rate of the re-liquefied object. Accordingly, the present invention maximizes the re-liquefaction efficiency, and thus has the effect of enabling the substantial treatment of the surplus evaporation gas as well as the linear velocity control as the re-liquefying control.

When re-liquefaction control is added to the accumulation control, in the present invention, firstly, at the time of the basic operation of the gas processing system 1, at least a portion of the evaporated gas pressurized in the evaporative gas compressor 50 is supplied to the re-liquefier 60 Setting. The ship then implements the gas treatment system 1 through the basic drive, and when the surplus evaporated gas is generated, it can accumulate in the liquefied gas storage tank 10 to control the surplus evaporated gas. At this time, the lower rate liquefied gas storage tank 10 is capable of accumulating pressure until the internal pressure of the tank becomes about 0.25 bar.

Specifically, when the evaporation gas flow rate supplied from the low-rate liquefied gas storage tank 10 to the refueling device 60 is A2 and the evaporated gas pressurized by the evaporation gas compressor 50 is supplied to the refueling device 60 When the evaporation gas flow rate is B2, the basic setting can be set to A2: B2 = 3: 1, for example. In this case, the flow rate of the evaporation gas supplied to the propulsion engine 70 by the evaporation gas pressurized by the evaporation gas compressor 50 with respect to the evaporation gas flow rate supplied from the low rate liquefied gas storage tank 10 to the refueling device 60 is 3: 2.

In the case where surplus evaporation gas is generated in the above-mentioned basic setting, the low saturation liquefied gas storage tank 10 can be accumulated until the internal pressure of the tank becomes about 0.25 bar for the treatment of the surplus evaporated gas, The evaporation gas flow rate supplied from the rate liquefied gas storage tank 10 to the refueling device 60 can be reduced.

At this time, A2: B2 is changed to 2.5: 0.5 since the same amount as that of the basic drive must be supplied to the propulsion engine 70. More specifically, for example, when A2 is 3 and B2 is 1, the amount consumed by the propulsion engine 70 is 2, and the amount 2 consumed by the propulsion engine 70 is not fluctuated do. Therefore, when A2 is changed to 2.5 at the time of accumulation, B2 is reduced to 0.5 because the amount consumed by the propulsion engine 70 is 2 as it is. That is, A2: B2 is changed to 2.5: 0.5 (5: 1)

Accordingly, the re-liquefier 60 has an effect of drastically improving the re-liquefaction rate because A2, which is the flow rate of the remanufacturing main body which serves as a refrigerant, is larger than the flow rate of the re-liquefied object B2. Accordingly, the present invention maximizes the re-liquefaction efficiency, and thus has the effect of enabling the processing of the surplus evaporation gas to be substantially controlled not only by the axial pressure control but also by the re-liquefying control.

As described above, the gas treatment system 1 according to the present invention has an effect of facilitating the treatment of the liquefied gas or the evaporated gas by suitably applying the liquefied gas storage tank 10 having a low vaporization rate to the gas treatment system 1 have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention. It is obvious that the modification and the modification are possible.

The control unit may include a valve (not shown) or a liquefied gas storage tank (not shown) provided on each of the lines L1 to L6 for controlling the above- The control can be implemented by being connected to and operated by a valve or various devices.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: gas treatment system 2: hull
10: Liquefied gas storage tank 20: Boosting pump
21: High pressure pump 30: Forced vaporizer
40: Heat exchanger 50: Evaporative gas compressor
50a: reciprocating evaporative gas compressor 50b: centrifugal evaporative gas compressor
60: Re-liquefier 60a: Evaporative gas heat exchanger
60b: refrigerant heat exchanger 61: gas-liquid separator
62: expansion valve 70: propulsion engine
70a: MEGI engine 70b: XDF engine
71: Gas Combustion Device (GCU) 72: Power Generation Engine
80: shaft generator 90: propeller
91: Propeller shaft
L1: evaporation gas supply line L2: liquefied gas supply line
L3: Evaporative gas first branch line L4: Evaporative gas second branch line
L5: evaporation gas remelting line L6: liquefied gas returning line

Claims (7)

A liquefied gas storage tank for storing liquefied gas;
An evaporative gas compressor for supplying evaporative gas generated in the liquefied gas storage tank to the fuel of the engine; And
And a liquefaction device for liquefying excess evaporative gas not supplied to the engine,
Wherein the excess evaporation gas introduced into the refloater is reduced by increasing the output of the engine to reduce excess evaporation gas not supplied to the engine. 2. The liquefaction apparatus according to claim 1,
And the extra evaporation gas is re-liquefied through a separate refrigerant. 2. The liquefied gas storage tank according to claim 1,
Wherein the liquefied gas is stored and has a low BOR of 0.7% to 0.9%. 2. The engine according to claim 1,
Pressure gas injection engine (XDF). 5. The method of claim 4,
An evaporation gas supply line connecting the liquefied gas storage tank and the engine and supplying evaporated gas generated in the liquefied gas storage tank to the engine; And
Further comprising a liquefied gas supply line connecting the liquefied gas storage tank to the engine and supplying the liquefied gas stored in the liquefied gas storage tank to the propulsion unit. 6. The method of claim 5,
A boosting pump provided on the liquefied gas supply line for pressurizing the liquefied gas stored in the liquefied gas storage tank; And
Further comprising a forced vaporizer for vaporizing the liquefied gas supplied from said boosting pump. The method according to claim 1,
A shaft generator provided on a rotating shaft of the engine; And
Further comprising a power generation engine that generates electricity using the evaporation gas or oil,
Wherein the shaft generator develops with an output increase of the engine,
And the power generation engine lowers the load by an amount of generation of the shaft generator.

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